Tesi sul tema "Follicular T cells"
Segui questo link per vedere altri tipi di pubblicazioni sul tema: Follicular T cells.
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Follicular T cells".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Trüb, Marta. "Follicular T helper cell populations". Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20466.
Abstract (sommario):
Humoral immunity provides protection against subsequent infections. Antigen-specific, high-affinity, class-switched antibodies are produced by B cells through rounds of proliferation, B cell receptor rearrangement and selection in the germinal centres (GC). T cells play an essential and indispensable role in this process and in the recent years the term T follicular helper cells (TFH) was coined to describe this cell subset. The aim of my thesis is to investigate whether there is more than one type of T cells within the TFH population and whether it has important functional consequences. Firstly, I use sheep red blood cell immunisation (SRBC) and Salmonella enterica infection to show phenotypical differences between TFH expressing high and low level of surface molecule PD-1. In order to investigate the relationship between different TFH populations gene profiling was carried out on the microarray platform. Detailed transcriptome analysis revealed the discrete nature of isolated TFH cell subsets and provided an overview of their genetic landscape. Secondly, I have investigated the dependence of TFH subsets on cognate interactions with B cell in SRBC model by generating BM chimeras. I have demonstrated that generation of PD-1HI TFH, but not of PD-1LO TFH, depends on antigen presentation by B cells. Furthermore, I have shown that provision of wild-type but not MHC II knock-out B cells rescues PD-1HI formation in BM chimeras after SRBC immunisation. Finally, I have explored plasticity within TFH subsets and showed that none of the populations is in a terminally differentiated state, as they can convert into one another. Thirdly, experiments with S. enterica model revealed that the absence of PD- 1HI TFH is independent of the splenic architecture disruption present within the first week of the response. Surprisingly, co-immunisation studies showed that PD-1HI population is not only present but even enhanced in the group which received both SRBC and S. enterica when compared to single immunisations. The work presented in the thesis documents that there is a significant and previously unappreciated heterogeneity within TFH subset. This knowledge is important for designing optimal vaccine strategies and treating autoimmune diseases, as in both processes the antibody production plays a crucial role and its manipulation (either enhancing or blocking antibody production, respectively) can significantly improve clinical interventions.
2
Sayin, Ismail. "Characterization of human T follicular regulatory cells". Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1560336991188191.
3
Misiak, Jan. "The interactions of stromal cells and follicular helper T cells resulting in a B-cell supporting, IL4-producing phenotype in the context of follicular lymphoma". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1B030.
Abstract (sommario):
Un microenvironnement riche en IL-4 a été mis en évidence dans le lymphome folliculaire (FL). Cette IL-4 impliquée dans la croissance tumorale a été démontrée comme principalement secrétée par les lymphocytes T follicular helper (Tfh). Dans cette étude, nous étudions l’interaction bidirectionnelle entre les cellules fibroblastiques réticulaires (FRC) dont le réseau est augmenté dans le FL et les lymphocytes Tfh par analyse des profils d’expression génique, et co-culture in vitro des lymphocytes Tfh primaires avec des cellules fibroblastiques humaines de type FRC-like. Nous démontrons que les cellules FRC-like augmentent in vitro la croissance des sous-populations de Tfh. De plus, nous avons mis en évidence une augmentation spécifique de la sécrétion d’IL-4 par les précurseurs Tfh (pre-Tfh) co-cultivés avec les cellules FRC-like, augmentation d’IL-4 impliquant les voies Notch et ICAM1/LFA1. Cette observation est particulièrement intéressante dans le contexte du FL car les lymphocytes pre-Tfh de FL comparés à des lymphocytes pre-Tfh d’amygdales non tumorales sont caractérisés par un profil d’expression génique enrichi en gènes des voies Notch et des intégrines en plus d’une surexpression d’IL-4. En conclusion, notre description de l’interaction entre les cellules stromales et les sous-populations Tfh démontrent une modification du profil cytokinique des Tfh au stade précurseur qui pourrait expliquer le profil cytokinique retrouvé dans le microenvironnement du FL, et apporter de nouveaux éléments pour la mise en évidence de nouvelles cibles thérapeutiquesThe enrichment of the microenvironment with tumor-promoting interleukin 4 (IL4) has been implicated in the pathogenesis of follicular lymphoma (FL) and was found to be conferred mainly by T follicular helper (Tfh) cells. In this study, we investigated the bidirectional crosstalk of fibroblastic reticular cells that are expanded in FL and Tfh cells with the analysis of gene expression profiles of the respective, and an in-vitro co-culture model of human induced FRC-like cells. We demonstrated that FRC-like cells enhance the growth of Tfh cell subsets in vitro. Crucially, we uncovered a specific upregulation of IL-4 secretion by precursor Tfh (pre-Tfh) cells co-cultured with FRC-like cells. Additionally, we demonstrated that Notch and ICAM1/LFA1 are two pathways involved in IL-4 secretion following FRClike cell / Tfh cell crosstalk. This observation was particularly interesting in FL context, because FL pre-Tfh cells display an enriched Notch and integrin gene expression profile as well as an overexpression of IL-4, compared to their tonsil counterpart. Altogether, we described new interactions between stromal cells and Tfh subsets and uncovered a specific cytokine profile modification at pre-Tfh stage after contact with FRC-like cells that could explain the high levels of IL-4 in FL and provide a novel target for therapy
4
Vanderleyden, Ine. "Follicular regulatory T cell migration and differentiation". Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288422.
Abstract (sommario):
The germinal centre (GC) response is critical for generating highly effective humoral immune responses and immunological memory that forms the basis of successful immunisation. Control of the output of the GC response requires Follicular regulatory T (Tfr) cells, a subset of Foxp3+ Treg cells located within germinal centres. Tfr cells were first characterised in detail in 2011 and because of this relatively little is known about the exact role of Tfr cells within the GC, and the mechanism/s through which they exert their suppressive function. At the outset of this work, the major barrier to understanding Tfr cell biology was the lack of appropriate tools to study Tfr cells specifically, without affecting Tfh cells or other Treg cell subsets. This thesis set out to develop a strain of mice that specifically lacks Tfr cells. A unique feature of Tfr cells is their CXCR5-dependent localisation within the GC. Therefore, genetic strategies that exclude Treg cells from entering the GC are a rational approach to generating a mouse model that lacks Tfr cells. To this end, I generated a strain of mice that lacks CXCR5 on Foxp3+ Treg cells. These animals show a ~50% reduction in GC localised Tfr cells, and a GC response that is comparable to control animals. These data indicated that redundant mechanisms are involved in Treg cell homing to the GC. I identified CXCR4 as a chemokine receptor that is also highly expressed on Tfr cells, and hypothesised that it may also be involved in Tfr cell localisation to the GC. Surprisingly, simultaneous deletion of both CXCR4 and CXCR5 in Treg cells resulted in a less marked reduction in Tfr cells compared to deletion of CXCR5 alone, suggesting that CXCR4 might be involved in negative regulation of Treg homing to the GC. These data identify both CXCR4 and CXCR5 as key regulators of Tfr cell biology. Bcl6 drives Tfr cell differentiation, but how this transcriptional repressor facilitates commitment to the Tfr cell subset is unknown. I hypothesised that Bcl6 drives Tfr cell differentiation by repressing Tbx21, the transcriptional regulator involved in the differentiation of Th1-like Treg cells. I tested this hypothesis in Bcl6fl/fl CD4cre/+ animals and unexpectedly found that loss of Bcl6 regulates Treg cell differentiation in the absence of immunisation or infection. I have demonstrated that thymic loss of Bcl6 results in an increase in activated effector Treg cells, which occurs very early in life. These data point to a novel role for Bcl6 in preventing early thymic Treg activation, indicating that Bcl6 has a global role in Treg development and differentiation that is not simply limited to Tfr cells.
5
Wang, Changna. "Follicular Dendritic Cells, Resting CD4+ T Cells and Human Immunodeficiency Virus Expression". BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2906.
Abstract (sommario):
Many events associated with Human Immunodeficiency Virus (HIV) infection/replication occur in and around the germinal centers (GCs) of secondary lymphoid tissues where follicular dendritic cells (FDCs) reside, suggesting that this microenvironment may contribute unique signaling that is important to viral progression. My research focused on characterizing signaling, both positive and negative, contributed by FDCs that affects HIV infection and replication. Specifically, I determined if FDC signals could induce the expression of latent HIV in T cells and if so, to characterize the signaling pathways involved. Moreover, I also examined the ability of FDCs to produce inhibitory signals that might block active virus expression. I approached these problems using FDCs from tonsils and coculturing these with primary CD4+ T cells or latently-infected Jurket cells with a GFP reporter. Results indicated that FDCs dramatically augmented HIV production of these cells. FDC signaling was costimulatory in nature and was mediated by soluble TNFα. However, when ex vivo latently infected T cells were treated with PMA/ionomycin or IL2/IL7, little virus expression was observed until FDCs were added, which greatly increased virus production. The transcription factor NFAT is important for the reactivation of latent HIV. Inhibition studies as well as ELISA suggested that JAK/STAT signaling pathway was involved in virus reactivation. Because FDCs produce prostaglandins (PGs) E2 and I2, I determined the effect of PGE2 and PGI2 analogs on HIV infected T cells. Results indicated that both the PGE2 and PGI2 analogs inhibited proliferation and activation-induced cell death of HIV infected T cells in a dose- and time-dependent manner. Additionally, it was shown that indomethacin and CAY10404, cyclooxygenase and cyclooxygenase-2 inhibitors, partially restored HIV production in the presence of FDCs, suggesting that FDC-produced PGE2 and PGI2 may inhibit virus replication. Thus, FDCs produce PGs that can block virus gene expression in T cells, which may be ideal for viral persistence. Therefore, FDC signaling appears to both promote and inhibit HIV production. A better understanding of FDC signaling and regulation in GCs may suggest new treatment strategies that would be beneficial to infected subjects.
6
Pandey, Shubham. "Identification of Interleukin 4 - CXCL12 supportive loop in follicular lymphoma". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1B031/document.
Abstract (sommario):
Le lymphome folliculaire (FL) est le lymphome B indolent le plus fréquent. Outre des altérations géniques récurrentes, le micro-environnement tumoral, et notamment les cellules stromales lymphoides,joue un rôle majeur dans le développement de ce cancer. Cependant, la caractérisation in-situ des cellules stromales lymphoïdes chez l'homme tout comme les facteurs menant à la polarisation du stroma en un stroma protumoral ont été peu étudiés. Dans cette thèse, nous avons montré, que les cellules stromales présentes dans les ganglions et la moelle osseuse envahis des patients atteints de FL surexpriment fortement la chimiokine CXCL12. Nous avons ensuite tenté de comprendre les mécanismes responsables de cette induction. Alors que les cellules B tumorales induisent une surexpression de la chimiokine CCL2 dans les cellules stromales de façon dépendante de leur synthèse de TNF, elles ne contribuent pas à l'induction de CXCL12. A l'inverse, le principal compartiment TCD4 impliqué dans la croissance tumorale du FL, les cellules T follicular helper (TFH), augmentent l'expression de CXCL12 dans les cellules stromales. Le taux d'IL-4, la principale cytokine produite par les TFH de FL, est d'ailleurs corrélé à celui de CXCL12 au sein de ma niche tumorale du FL. De plus, à l’aide d'un modèle de différenciation en stroma lymphoide, nous avons démontré que l’IL4 induit l’expression de CXCL12 par les cellules stromale in vitro. Cette production est augmentée quand les cellules stromales sont déjà engagées vers la voie de différentiation lymphoide par un traitement TNF/LT qui favorise l'activation de STAT6 par l'IL-4. Nous avons validé ces résultats dans un modèle de formation d'organe lymphoide ectopique chez la souris. Enfin, CXCL12 induit la migration et l'adhésion au stroma des B de FL via l'activation de cascades de signalisations qui peuvent être abrogées par l'utilisation d'un inhibiteur de Btk utilisé en clinique, l'Ibrutinib. Ces résultats sont en faveur de l'intérêt de considérer la boucle IL-4/CXCL12 pour développer de nouvelles stratégies thérapeutiques dans cette pathologie constamment fataleFollicular lymphoma (FL) is the most frequent indolent B-cell lymphoma. Beside recurrent genetic alterations, tumor microenvironment, including lymphoid stromal cells, has been shown to play a key role in FL development. However, in situ characterization of lymphoid stromal cells is still lacking in humans and there are very few studies focusing on the factors that could lead to stroma polarization in normal and pathological context. In this thesis, we showed first that in FL, lymph node (LN) and bone marrow (BM) infiltrating stromal cells highly express the chemokine CXCL12. We next focused on the mechanisms underlying this upregulation. Interestingly, whereas malignant FL B cells induced overexpression of CCL2 in stromal cells in a TNF-dependent manner, they did not contribute to CXCL12 induction. Conversely, FL-infiltrating follicular helper T cells (FL-TFH), the key FL-supportive T-cell subset could trigger CXCL12 expression in stromal cells. IL-4 is the main FL-TFH-derived cytokine and showed a positive correlation with CXCL12 expression inside FL cell niches. Moreover, based on our in vitro lymphoid stroma differentiation model, we demonstrated that IL-4 promoted CXCL12 expression in stromal cells, together with a phenotype close to that identified in situ within FL cell niche. Such IL4 dependent CXCL12 regulation is more pronounced in stromal cells already committed towards lymphoid stromal cells by a prestimulation by TNF/LT in association with an increased STAT6 activation. These data were validated in a model of ectopic lymphoid organ formation in mice. Finally, CXCL12 induced FL B-cell migration, and adhesion to stromal cells through the activation of a signaling pathway that could be abrogated by the Btk inhibitor Ibrutinib. These data argue for considering IL-4/CXCL12 axis as a potential therapeutic target to disrupt FL protective cell niche in this still fatal malignancy
7
Kawamoto, Shimpei. "Preferential Generation of Follicular B Helper T Cells from Foxp3+ T Cells in Gut Peyer's Patches". Kyoto University, 2011. http://hdl.handle.net/2433/142110.
8
Thomas, Jessica. "T follicular helper cells in health and inflammatory bowel disease". Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/t-follicular-helper-cells-in-health-and-inflammatory-bowel-disease(1c45e306-6a7b-4d84-b02f-e4e1c500dbea).html.
Abstract (sommario):
The intestinal IgA response has features that are different to those of the systemic humoral response, which is dominated by IgG. Although the IgA response, like the IgG response, includes an antigen specific component, it is also associated with polyspecificity and autoimmunity. The profile of intestinal immunoglobulins changes in inflammatory bowel disease (IBD) where there is a disproportionate increase in IgG production and in ulcerative colitis (UC), this includes the production of autoantibodies. In this thesis, two immunoregulatory T cell subsets that could influence the intestinal B cell response have been studied; T follicular helper cells (TFH) and regulatory T cells (Treg). Results in chapter 3 show that there is a higher density of TFH in gut associated lymphoid tissue (GALT) compared to peripheral lymphoid tissue due to a higher density of CD57- TFH- The expression of cytokines and CD40L was almost comparable between CD57+ and CD57- TFH- However, culturing experiments suggest that CD57-TFH may develop into CD57+ TFH and there is a constant turnover of TFH in the gut. Experiments in chapter 4 attempted to seek evidence for a developmental relationship between TFH and Treg by analysis of T cell receptor sequences. No evidence of plasticity between these subsets was observed. Experiments in chapter 5 set out to characterise TFH in IBD. In the appendix of UC patients, nearly all TFH were CD57+ and at a high density within germinal centres (GC). This thesis concludes that TFH are more phenotypically diverse and denser in GALT compared to peripheral lymphoid tissue. This may reduce the threshold for GC B cell survival in the gut permitting the propagation of plasma cells that secrete polyspecific and autoreactive IgA. TFH are denser still in the small GC in UC appendix. This may be relevant to the production of autoantibodies and disease pathogenesis.
9
Townsend, William Mathew. "A study of CD4+ follicular helper T cells in the follicular lymphoma microenvironment and normal germinal centres". Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/a-study-of-cd4-follicular-helper-t-cells-in-the-follicular-lymphoma-microenvironment-and-normal-germinal-centres(744b7c2f-f848-4c41-8fd1-687dc2201f6b).html.
Abstract (sommario):
Follicular lymphoma is a common B cell malignancy which usually follows an indolent course but it is a heterogeneous disease and there are no biomarkers that can accurately predict outcome or prognosis at the time of diagnosis. There is now clear evidence that the microenvironment plays an important role in the pathogenesis of this disease and the composition of the microenvironment has been linked to prognosis with variable results. The biological basis for the influence of the microenvironment and the contribution of individual cell types remain unclear. In this research we focus on CD4+ T cell subsets, in particular T follicular helper cells and characterise their number, phenotype and distribution in follicular lymphoma with comparisons to normal germinal centres in reactive lymph nodes. We also investigate if T follicular helper cells have a role in promoting B cell proliferation, and induction of AID, whether B and T cells form immunological synapses in follicular lymphoma, and if there is evidence of antigen specificity in the T-cell receptor repertoire.
10
Rasheed, Mohammed Ata Ur. "Gene signatures and functional analysis of follicular B helper T cells". [S.l.] : [s.n.], 2006. http://www.diss.fu-berlin.de/2006/538/index.html.
11
Sabir, Suleman Rahman. "Dissecting the role of T-follicular helper cells in experimental atherosclerosis". Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/7665/.
12
Wallin, Elizabeth. "The germinal centre reaction and follicular T cells in alloantibody formation". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:e4ecdd13-7c1e-4d4e-8491-8a22857cdb86.
Abstract (sommario):
Kidney transplantation is the optimal treatment for end-stage renal failure, however graft lifespan remains limited, and a major cause of graft loss is chronic, low-grade antibody-mediated damage. Understanding more about how these antibodies are produced, and how immunosuppression affects cells producing them, may allow both prediction of those at risk, and a mechanism for preventing or minimising antibody production, therefore improving graft lifespan. In particular, interest has grown in CD4 T cells known as circulating T follicular helper (cTfh) and T follicular regulatory (cTfr) cells, which appear to correlate with antibody production in vaccination, autoimmunity and potentially transplantation, however little is known about how immunosuppression alters these cells and their function. This study aimed to establish whether cTfh and cTfr cells could be used to predict the risk of de novo donor-specific antibody (DSA) formation in 61 kidney and simultaneous pancreas kidney (SPK) transplant recipients. Results suggested that high cTfh cells and low cTfr associated with de novo DSA formation, and the ratio of the two cells may be useful for identifying at-risk patients. Different immunosuppression regimens were associated with different levels of risk for de novo DSA formation, with basiliximab induction combined with azathioprine maintenance therapy having the lowest risk, despite being considered a less intensive regimen. In vitro experiments suggest this may be due to a differential effect of azathioprine on cTfh and B cells compared to mycophenolate mofetil, an alternative maintenance agent. Combining the in vitro and clinical data suggests that azathioprine may reduce the risk of de novo DSA formation after transplantation compared to other agents because of its effects on B cells, cTfh and cTfr. This is an exciting development that warrants further investigation.
13
Pfeilschifter, Janina Marie. "Targeting B non-Hodgkin lymphoma and tumor-supportive follicular helper T cells with anti-CXCR5 CAR T cells". Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/23169.
Abstract (sommario):
CAR-T-Zell-Therapie ist eine vielversprechende neuartige Behandlungsform für Patienten mit aggressiven B-Zell Non-Hodgkin-Lymphomen (B-NHL). In dieser Arbeit wurde die anti-CXCR5 CAR-T-Zell-Therapie als Alternative zur anti-CD19 CAR-T-Zell-Therapie für die Behandlung von reifen B-NHLs untersucht. CXCR5 ist ein B-Zell-homing Rezeptor, der von reifen B Zellen und follikulären T-Helferzellen (TFH Zellen) exprimiert wird. TFH Zellen wurden als tumor-unterstützend in chronisch lymphatischer Leukämie (CLL) und im follikulären Lymphom (FL) beschrieben. Dieses Expressionsmuster erlaubt es, auf einzigartige Weise zeitgleich die malignen Zellen und die tumorunterstützende Mikroumgebung mithilfe von CAR-T-Zell-Therapie gerichtet gegen einen Chemokinrezeptor anzugreifen. Die wichtigsten Ergebnisse dieser Arbeit waren, dass (1) die anti-CXCR5 CAR T-Zellen zielgerichtet CXCR5 positive reife B-NHL Zelllinien und Patientenproben in vitro eliminierten und eine starke anti-Tumor Reaktivität in einem immundefizienten Xenotransplantationsmausmodell zeigten, (2) die anti-CXCR5 CAR T-Zellen zielgerichtet die tumorunterstützenden TFH Zellen in CLL und FL Patientenproben in vitro erkannten und dass (3) CXCR5 ein sicheres Expressionsprofil zeigte. CXCR5 war stark und häufig auf B-NHL exprimiert und die Expression auf gesundem Gewebe war auf lymphoide Zellen beschränkt. Zusammenfassend lässt sich sagen, dass die anti-CXCR5 CAR-T-Zell-Therapie eine neue Behandlungsmöglichkeit für Patienten mit reifen B-NHL darstellt, indem durch die anti-CXCR5 CAR-T Zellen sowohl der Tumor als auch ein Anteil der tumorunterstützende Mikroumgebung eliminiert werden.
Im zweiten Teil der Arbeit wurde das Eμ-Tcl1 murine CLL Lymphommodell genutzt um die Auswirkung der Lymphomentwicklung auf die CXCR5+ T Zellen zu untersuchen. Mittels RNA-Einzelzell-Sequenzierung konnte ein profunder Einfluss des Lymphomwachstums auf das T Zell-Kompartiment der Mäuse, denen Eμ-Tcl1 Zellen gespritzt wurden, gezeigt werden.CAR T cell therapy is a promising new treatment option for patients suffering from aggressive B non-Hodgkin lymphomas (NHLs). In CAR T cell therapy, patient-derived T cells are genetically modified to express a chimeric receptor commonly directed towards a surface antigen expressed by neoplastic cells. In this thesis, anti-CXCR5 CAR T cell therapy was investigated as an alternative to anti-CD19 CAR T cell therapy for the treatment of mature B-NHLs. CXCR5 is a B cell homing receptor expressed by mature B cells and follicular helper T (TFH) cells. TFH cells were described to support the tumor cells in chronic lymphocytic leukemia (CLL) and follicular lymphoma (FL). This expression pattern allows simultaneous targeting of the malignant cells and the tumor-supporting microenvironment by CAR T cell therapy against a chemokine receptor in an unprecedented manner. Main findings included that (1) anti-CXCR5 CAR T cells targeted specifically CXCR5 expressing mature B-NHL cell lines and patient samples in vitro and showed strong in vivo anti-tumor reactivity in an immunodeficient xenograft mouse model, (2) anti-CXCR5 CAR T cells targeted tumor-supportive TFH cells derived from CLL and FL patient samples in vitro and (3) CXCR5 showed a safe expression profile. CXCR5 was strongly and frequently expressed by B-NHLs and its expression on healthy tissue was restricted to lymphoid cells. In summary, anti-CXCR5 CAR T cell therapy presents a novel treatment option for patients suffering from mature B-NHLs by eliminating the tumor and part of the tumor-supportive microenvironment. The second part of the project, the Eμ-Tcl1 murine lymphoma model, which mimics human CLL, was used to study the impact of lymphomagenesis on CXCR5+ T cells. Using single cell RNA sequencing, a profound influence of lymphoma growth on the T cell compartment in Eμ-Tcl1 tumor-challenged mice could be shown.
14
Miles, Brodie, Shannon M. Miller e Elizabeth Connick. "CD4 T Follicular Helper and Regulatory Cell Dynamics and Function in HIV Infection". FRONTIERS MEDIA SA, 2016. http://hdl.handle.net/10150/622733.
Abstract (sommario):
T follicular helper cells (T-FH) are a specialized subset of CD4 T cells that reside in B cell follicles and promote B cell maturation into plasma cells and long-lived memory B cells. During chronic infection prior to the development of AIDS, HIV-1 (HIV) replication is largely concentrated in T-FH. Paradoxically, T-FH numbers are increased in early and midstages of disease, thereby promoting HIV replication and disease progression. Despite increased T-FH numbers, numerous defects in humoral immunity are detected in HIV-infected individuals, including dysregulation of B cell maturation, impaired somatic hypermutation, and low quality of antibody production despite hypergammaglobulinemia. Clinically, these defects are manifested by increased vulnerability to bacterial infections and impaired vaccine responses, neither of which is fully reversed by antiretroviral therapy (ART). Deficits in T-FH function, including reduced HIV-specific IL-21 production and low levels of co-stimulatory receptor expression, have been linked to these immune impairments. Impairments in T-FH likely contribute as well to the ability of HIV to persist and evade humoral immunity, particularly the inability to develop broadly neutralizing antibodies. In addition to direct infection of T-FH, other mechanisms that have been linked to T-FH deficits in HIV infection include upregulation of PD-L1 on germinal center B cells and augmented follicular regulatory T cell responses. Challenges to development of strategies to enhance T-FH function in HIV infection include lack of an established phenotype for memory T-FH as well as limited understanding of the relationship between peripheral T-FH and lymphoid tissue T-FH. Interventions to augment T-FH function in HIV-infected individuals could enhance immune reconstitution during ART and potentially augment cure strategies.
15
Weber, Jan Phillip [Verfasser]. "Generation, Maintenance and Fate of T Follicular Helper Cells / Jan Phillip Weber". Berlin : Freie Universität Berlin, 2013. http://d-nb.info/1042940827/34.
16
Blackburn, Matthew James. "Characterization of a CD4 T cell population enriched in T follicular helper cells in macaques during chronic SIV infection". Thesis, Boston University, 2013. https://hdl.handle.net/2144/12055.
Abstract (sommario):
Thesis (M.A.)--Boston UniversityA preventive vaccine for HIV infection is urgently needed to curb the HIV/AIDS pandemic. To date only one human trial testing the combination of an ALVAC-HIV/gp120 protein strategy (Thai trail) has resulted in some protection from HIV infection. The correlate of protection elicited by this vaccine strategy was non-neutralizing antibodies to the gp120 protein. Nevertheless, the overall efficacy of the Thai trial was limited (31.2%); indicating that more work needs to be performed to ameliorate the Thai trial vaccine efficacy. T Follicular Helper (TFH) cells are subset of CD4 T cells that localize within the follicular region of lymph nodes, are required for the formation and maintenance of the germinal center, and provide help to B cells. TFH may therefore be critical for the development of effective antibodies to HIV/SIV. Here, we characterize TFH in different lymphoid compartments of naïve and infected rhesus macaques, the preferred animal model to assess the efficacy of candidate vaccines for HIV. First, we looked at the frequency of TFH within the various lymphoid compartments. TFH, characterized as PD-1++, ICOS++ and CCR7-, were higher within the spleen, the lamina propria of the rectal mucosa, and the tonsils than the lymph nodes. Interestingly, during chronic SIV infection, the frequency of TFH significantly increased in the lymph nodes while remaining fairly constant in the spleen. We then functionally characterized TFH in the lymph nodes of infected and non-infected macaques by performing an intracellular cytokine staining to measure the production of IFN-γ, TNF-α, IL-17, and IL-21 after in vitro stimulation with PMA-ionomycin and SIV-env and SIV-gag overlapping peptides. Interestingly, while TFH (CCR7-/PD-1++) and non-TFH were capable of producing IFN-γ, TNF-α and IL-21 after stimulation with PMA- ionomycin, in chronically infected animals, we observed an impaired production of IL-21. As localization in the germinal center is believed to be relevant for TFH functionality, we established a migrational assay as a way to better discriminate TFH from non-TFH in macaques. The aim was to mimic the in vivo migration of non-TFH to the T cell zone and of TFH to the B cell zone of the lymph nodes, induced by CCL19/CCL21, and CXCL13, respectively, using a two-step assay. We obtained an enrichment of phenotypic defined non-TFH (first migration: CCL19/CCL21) and TFH cells (second migration: CXCL13) from lymph nodes from both naïve and infected macaques. We show that CD4 T cells from naïve macaques that migrated to the CXCL13 had higher levels of Bcl-6 expression and were capable of producing higher levels of IL-21 and lower levels of IFN-γ than cells that migrated to the CCL19 and CCL21-T zone chemokines. Additionally, in SIV infected macaques, CD4 T cells that migrated to CXCL13 were impaired in the production of IL-21 following stimulation with PMA- ionomycin. These results validate our two-step migration assay as an innovative way to study TFH in macaques.
17
Asrir, Assia. "Caractérisation phénotypique et fonctionnelle des différentes populations de Lymphocytes T CD4 Folliculaires Mémoires". Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30084/document.
Abstract (sommario):
Les LT CD4 folliculaires (TFH) forment un lignage distinct de LT contrôlant spécifiquement les lymphocytes B (LB) et la mise en place de la mémoire B. Alors que ces cellules étaient considérées comme des cellules effectrices uniquement, récemment il a été identifié, chez l'Homme et la souris, l'existence de TFH mémoires. Les TFH mémoires en tant que LT CD4 mémoires sont nécessaires, en cas de nouvelle rencontre avec l'antigène (Ag), à la mise en place d'une réponse Anticorps (Ac) rapide, efficace et de forte affinité. En effet, leur présence est corrélée à la génération et le maintien à long terme d'Ac de forte affinité lors d'infections virales. De plus, des études récentes montrent que l'analyse des TFH mémoires dans le sang périphérique peut fournir des indices pour comprendre le mode d'action des vaccins ainsi que la pathogenèse de maladies auto-immunes. Par ailleurs, dans le contexte de nombreuses maladies, de récents travaux suggèrent que l'évaluation de la fréquence et du phénotype des TFH mémoires dans le sang périphérique pourrait servir de bio-marqueur à l'établissement de diagnostique. Tout comme les cellules B mémoires qui sont subdivisées en différentes sous-populations en fonction de leur localisation et de la nature de leur Ac, différentes populations de TFH mémoires ont été récemment identifiées. Certaines se situent dans les organes lymphoïdes secondaires (OLS) drainants le site d'immunisation, de vaccination ou d'infection, ou circulantes dans les OLS non-drainants ou à proximité des plasmocytes à longue durée de vie dans la MO. Ces observations soulèvent donc la question majeure de leurs phénotypes, différences fonctionnelles et interactions face aux différentes populations de cellules B mémoires. L'objectif de mes travaux de Thèse a consisté à étudier l'hétérogénéité phénotypique et fonctionnelle présente entre ces différentes populations de TFH mémoires aux localisations diverses. De plus au vu de l'hétérogénéité existante au sein des LB mémoires (nœuds lymphatiques ou rate) et plasmocytes à longue durée de vie (MO), nous avons aussi évalué l'interaction cellulaire et fonctionnelle qui a lieu entre ces populations mémoires. Dans ce contexte, nous avons développé un modèle expérimental unique de vaccination protéique chez la souris sauvage non modifiéeT Helper Follicular (TFH) cells form a distinct lineage of helper T cells and they specifically control B cells and memory B cell generation. While these cells were considered as effector cells, recently it was identified in Human and in mouse, the existence of memory TFH cells. Memory TFH cells, as CD4 memory T cells, are necessary in case of antigen (Ag) rechallenge to establish a fast, efficient and high affinity Antibody (Ab) response. Indeed, their presence is correlated with the generation and the long-term maintenance of high affinity Ac during viral infections. Moreover, recent studies have shown that analysis of memory TFH cells in the blood may provide clues to understanding the mode of action of vaccines and the pathogenesis of autoimmune diseases. In addition, in the context of many diseases, recent works have also suggested that the frequency and phenotype of memory TFH cells in the blood could serve as a biomarker for diagnosis. Likewise to memory B cells that are subdivided into different cell populations based on their location and the nature of their Ab, different populations of memory TFH cells have recently been identified. Some are in secondary lymphoid organs (SLO) draining the site of immunization, vaccination or infection, or circulating in the non-draining SLO or near the long-lived plasma cells (PC) in bone marrow (BM). These observations raise the question of their phenotypes, functional differences and interactions with the different subsets of memory B cells. The aim of my thesis was to study the phenotypic and functional heterogeneity between the different subsets of memory TFH cells. Due to the heterogeneity of memory B cells (draining lymph nodes or non-draining spleen) and long-lived PCs (BM), we also evaluated the cellular and functional interaction that occurs between these different memories populations. In this context, we have developed a unique experimental model of protein vaccination in unmodified wild-type mice. Specifically, after immunization, we evaluated the development of memory TFH cells and memory B cells specific for the same Ag in the draining SLO and circulating in the spleen and BM. We demonstrated that local memory TFH cells (that reside in the draining SLO) exhibit a more polarized phenotype than their circulating counterparts (present in non-draining SLO)
18
Pfeilschifter, Janina Marie [Verfasser]. "Targeting B non-Hodgkin lymphoma and tumor-supportive follicular helper T cells with anti-CXCR5 CAR T cells / Janina Marie Pfeilschifter". Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1241116989/34.
19
Alexander, Carla-Maria Alana. "T regulatory cells and the germinal center". Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1117.
Abstract (sommario):
Germinal center (GC) reactions are central features of T cell-driven B cell responses, and the site where antibody (Ab) producing cells and memory B cells are generated. Within GCs, a range of complex cellular and molecular events occur which are critical for the generation of high affinity Abs. These processes require exquisite regulation not only to ensure the production of desired Abs, but to minimize unwanted autoreactive or low affinity Abs.
To assess whether T regulatory cells (Treg) participate in the control of GC responses, immunized mice were treated with either an anti-glucocorticoid-induced TNFR-related protein (GITR) mAb or an anti-CD25 mAb to disrupt Treg activity. In both groups of treated mice, the GC B cell pool was significantly larger compared with control treated animals, with switched GC B cells composing an abnormally high proportion of the response. With these results indicating Tregs influence on GC dynamics, experiments were conducted to determine if Tregs were located in the GC, which subset of Treg was involved and by which mechanisms were their functions being effected. Within the spleens of immunized mice, CXCR5+ and CCR7- Tregs were documented by flow cytometry and Foxp3+ cells were found within GCs using immunohistology. Studies demonstrated administration of either anti-TGF-β or anti-IL-10R blocking mAb to likewise result in dysregulated GCs, suggesting that generation of inducible Tregs is important in controlling the GC response. Blockade of two Treg methods of suppression, PD-1/PD-L1 pathway and CTLA-4, also resulted in disrupted GCs, indicating the possible use of them for suppression by Treg. Collectively, these findings indicate that Tregs contribute to the overall size and quality of the humoral response by controlling homeostasis within GCs.
20
Le, Thi Kieu Suong. "Caractérisation phénotypique et fonctionnelle des lymphocytes T infiltrants dans les lymphomes B humains". Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM5006.
Abstract (sommario):
Les lymphomes B sont des cancers du système lymphatique se développant à partir des cellules B. Il devient évident que le développement des cellules B malignes dépend d’interactions avec les cellules immunes dans leur microenvironnement. Nous avons étudié la caractérisation des lymphocytes T intra tumoraux afin de comprendre leur contribution dans la lymphomagenèse et leur potentiel thérapeutique dans les lymphomes B comme le lymphome diffus à grandes cellules B (DLBCL), le lymphome folliculaire (FL) et le lymphome Hodgkinien classique (cHL)Nous avons mis en évidence une différence importante, quantitative et qualitative, entre la composition immunitaire de différents lymphomes B, notamment au niveau des lymphocytes T intra tumoraux. Le FL se caractérise par une accumulation des lymphocytes T régulateurs (Tregs) exprimant ICOS, pouvant supprimer les cellules B lymphomateuses. La génération des Tregs ICOS+ est favorisée par le contact avec les cellules B lymphomateuses exprimant ICOSL. Quant à lui, le DLBCL a beaucoup de lymphocytes TCD8 coexprimant PD1 et TIM3 possédant un état de dysfonctionnement dit « épuisement », lymphocytes dont la proportion est corrélée à leur niveau de dysfonctionnement et à leur capacité de réponse au blocage des récepteurs inhibiteurs. Enfin, dans certains lymphomes B, en particulier le cHL, nous avons découvert une sous population de TCD8, dite « TFH-like » pour leur similarité phénotypique et fonctionnelle avec les lymphocytes T auxiliaires folliculaires (TFH). Ces données indiquent l’hétérogénéité des composants immunitaires entre différents lymphomes B et sont une piste pour une future thérapie ciblée dans le traitement du lymphomeB-cell lymphomas represent a heterogeneous group of cancers that affect B cells in the lymphatic system. It has become evidence that malignant B cells depend on various interactions with microenvironmental immune cells for their development. Our study focuses on characterization of intra-tumoral T cells in order to understand their contribution in pathogenesis and their therapeutic potentials in the most frequent B cell-lymphoma such as Diffuse large B-cell lymphoma (DLBCL), Follicular lymphoma (FL) and classical Hodgkin lymphoma (cHL).During this work, we have demonstrated a significant quantitative and qualitative difference between different B-cell lymphoma immune composition, especially between their intra-tumoral T cells. FL is characterized by the accumulation of regulatory T cells (Tregs) expressing ICOS, with ability to suppress lymphoma B cells. Generation of Tregs ICOS+ is prompted by cell contact with the lymphoma B cells expressing ICOSL. On the other hand, DLBCL have high level of TCD8 coexpressing PD1 and TIM3 displaying an exhaustion state, which proportion is correlated with their dysfunction level and with their responsiveness to inhibitor receptors blockade. Finally, in some B-cell lymphoma cases, especially cHL, we found the existence of a TCD8 subset, called TFH-like due to their phenotypic and functional similarity with follicular helper T cells (TFH).These data show heterogeneity of immune components between the different B lymphomas, and give opportunity for targeted therapy in lymphoma treatment
21
Ollerton, Matthew T. "Capacity of Human Immunodeficiency Virus Targeting Chimeric Antigen Receptor T Cells to Eliminate Follicular Dendritic Cells Bearing Human Immunodeficiency Virus Immune Complexes". BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/7240.
Abstract (sommario):
An important obstacle to a functional cure for HIV/AIDS is the persistence of viral reservoirs found throughout the body in various cells and tissues. Reservoirs can be latently infected cells, or in the case of follicular dendritic cells (FDC), non-infected cells that trap infectious virus on their surface through immune complexes (HIV-IC). Although several strategies have been employed to target and eliminate viral reservoirs, they are short-lived and ineffective. In an attempt to provide a long-term approach, chimeric antigen receptor T (CAR-T) cells were designed to eliminate native HIV on FDCs. Although effective at eliminating HIV-infected cells, and halting spreading infection, their ability to eliminate the viral reservoir found on (FDCs) remains unclear. We used a novel second-generation CAR-T cell expressing domains 1 and 2 of CD4 followed by the mannose binding lectin (MBL) to allow recognition of native HIV envelope (Env) to determine the capacity to respond to the viral reservoir found on FDCs. We employed a novel fluorescent lysis assay, the Carboxyfluorescein succinimidyl ester (CFSE) release assay, as well as flow cytometric based assays to detect functional CAR-T activation through IFN-γ production and CD107a (i.e., LAMP1) membrane accumulation to test cytolytic capacity and functional activation of CD4-MBL CAR-T cells, respectively. We demonstrated their efficacy at eliminating HIV-infected cells or cells expressing gp160. However, these CAR-T cells were unable to lyse cells bearing surface bound HIV-IC. We found that failed lysis was not a unique feature of a resistant target, but a limitation in the CAR-T recognition elements. CAR-T cells were inactive in the presence of free HIV or in the presence of concentrated, immobilized virus. Further experiments determined that in addition to gp120 recognition by the CAR-T, the adhesion molecule ICAM-1 was necessary for efficient CAR-T cell killing of HIV-infected cells. CAR-T cell activity and killing were inhibited in the presence of ICAM-1 blocking antibody. These results suggest that other factors, such as adhesion molecules, play a vital role in CAR-T responses to HIV-infected cells. In addition, our findings highlighted the necessity to consider all models of HIV reservoirs, including FDCs, when evaluating therapeutic efficacy.
22
PODESTA', MANUEL ALFREDO. "STEPWISE DIFFERENTIATION OF IL21-PRODUCING FOLLICULAR HELPER T CELLS REVEALS DISTINCT DEVELOPMENTAL AND FUNCTIONAL STATES". Doctoral thesis, Università degli Studi di Milano, 2023. https://hdl.handle.net/2434/951499.
Abstract (sommario):
The interaction of follicular helper T (Tfh) cells with B cells within the germinal center of secondary lymphoid organs is essential for the formation of high affinity antibodies, a key effector mechanism of adaptive immunity. Interleukin (IL)-21 is a proinflammatory cytokine produced by Tfh cells, however the signals that license IL-21 production by these cells during their differentiation are unknown. Here we use fate mapping and reporter strategies to show that, after initial differentiation, Tfh cells transition to an IL-21-expressing Tfh21 stage, which is extrinsically regulated by follicular regulatory T (Tfr) cells. Using single cell RNA sequencing, we uncover additional developmental stages, including an earlyTfh21 stage prior to full Tfh21 differentiation, as well as an exTfh21 stage after Tfh21 development marked by loss of IL-21. The transcriptional and epigenetic landscape is formed in the earlyTfh21 stage and is maintained throughout the exTfh21 state, suggesting terminal differentiation. We also clarify that the transcription factor Foxp1 intrinsically regulates the transition between these stages in Tfh cells. Through selective in vivo deletion of IL21-experienced Tfh cells, we show that these subsets control antigen-specific germinal center formation, maintenance and somatic hypermutation at distinct stages of the germinal center response to a SARS-CoV-2 protein vaccine. Together, these studies demonstrate the transitionary stages of Tfh development and how control of progression through these stages regulates germinal center responses. Regulation and fine-tuning of Tfh developmental stages could be leveraged to promote protective immunity or to restrain pathogenic antibody responses.
23
Abduh, Maisa. "Follicular CD4 T Cells Tutor CD8 Early Memory Precursors : an Initiatory Journey to the Frontier of B Cell Territory". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS371.
Abstract (sommario):
Les lymphocytes T CD8+ spécifiques de l'antigène sont impliqués dans la réponse immunitaire adaptative et jouent un rôle essentiel dans la protection de l'hôte contre l'infection par des pathogènes intracellulaires. Cette protection de longue durée dépend de la génération de réponses lymphocytaires T CD8+ mémoires, hautement fonctionnelles en termes de fréquence et de fonctionnalité, après réinfection.Après présentation de l'antigène, une cellule T CD8 naïve subit une forte expansion clonale, générant une population hétérogène de cellules activées qui est dominée, au sommet de l'expansion, par des effecteurs CD8 de courte durée (SLEC). Cette expansion est suivie d'une phase de contraction massive par apoptose. Quelques cellules survivent à cette phase de contraction et finissent par se différencier en cellules mémoire hautement compétentes. Les processus par lesquels et le moment où se différencient les précurseurs de mémoire (MPECs) restent largement inconnus, tout comme les étapes ultérieures de leur maturation en cellules mémoire pleinement fonctionnelles. Les signaux d'aide provenant des cellules T CD4+ sont clairement requis tout au long du processus de maturation des MPEC.Notre équipe a montré que les lymphocytes T CD4+ régulateurs FoxP3+ (Tregs) favorisent la maturation des MPEC en limitant l'exposition à l'IL-2 et en fournissant des signaux inhibiteurs, mais ce n'est probablement qu'une facette de l'aide complexe et multiforme apportée par les cellules T CD4+ au MPEC. Les Tregs agissent sur des MPEC préexistants. Les réponses mémoire B et CD8+ partagent des caractéristiques communes, telles que l'expression du facteur de transcription Bcl-6. Les lymphocytes T CD4+ folliculaires (Tfh) sont les principaux producteurs de la cytokine IL-21. Bien que les mécanismes par lesquels les Tfh induisent l’expression de Bcl-6 dans les cellules B doivent être clarifiés, ils pourraient inclure l’IL-21 et l’interaction CD40-CD40L.Dans ce projet de thèse, nous avons étudié le rôle potentiel des Tfh dans l'initiation de la différenciation mémoire T CD8+, dans des modèles de souris transgéniques permettant une déplétion transitoire et sélective des Tfh, infectées par la bactérie recombinante Listeria monocytogenes-OVA.Nous avons montré que dès 2 jours après l'infection, les MPECs très précoces peuvent être identifiés par l’expression du récepteur de chimiokine CXCR5. Ces précurseurs précoces, qui ont un phénotype effecteur, se développent et migrent temporairement à la jonction des zones T et B, où ils interagissent avec les Tfh puis perdent leur expression CXCR5.Cette interaction avec les Tfh, considérés jusqu'à présent comme des auxiliaires exclusifs des cellules B, est nécessaire pour que les MPECs CD8+ deviennent des cellules mémoire compétentes sensibles à l'IL-21, capables de générer des réponses effectrices secondaires efficaces.Cette étude dévoile les premières étapes cruciales dans la génération de la mémoire CD8+, identifie CXCR5 comme le premier marqueur connu des MPECs CD8+, révèle l’implication fondamentale des Tfh dans le CD4 help et indique une coordination possible, via les Tfh, entre les voies de différentiation mémoire CD8+ et B. Ces résultats peuvent avoir des implications pour la conception du vaccin et de l'immunothérapieAntigen-specific CD8 T cells are involved in the adaptive immune response and play a critical role in protecting the host from infection by intracellular pathogens. This long-lasting protection depends on the generation of memory CD8+ T cell responses, which are highly functional in terms of frequency and functionality, after secondary infection.Following antigen activation, a naive CD8 T cell undergoes strong clonal expansion, generating a heterogeneous population of activated cells that is dominated, at the peak of expansion, by short-lived CD8 effectors (SLECs). This expansion is followed by a phase of drastic contraction through massive apoptosis. A few cells survive this contraction phase and eventually become highly competent memory cells. Precisely when and how these memory precursors (MPECs) are generated is largely unknown, and so are the subsequent steps of their maturation into fully functional memory cells. Help signals from CD4+ T cells are clearly required throughout the MPEC maturation process.Our team has previously shown that FoxP3+ regulatory CD4+ T cells (Tregs) favor MPECs maturation by limiting exposure to IL-2 and by providing inhibitory signals, but this is probably only one facet of the complex and multifaceted help provided by CD4+ T cells to MPEC, and Tregs act on pre-existing MPECs.B-cell memory and CD8+ T cell memory share some common features, such as the expression of the transcription factor Bcl-6. Tfh are major producers of the cytokine IL-21. The mechanisms by which Tfh induces Bcl-6 in B-cells need to be clarified, they might include IL-21 and CD40-CD40L.In this PhD project, we have investigated the potential role of Tfh on the initiation of CD8 memory differentiation, in transgenic mice models, allowing transient and selective depletion of Tfh cells, infected by recombinant Listeria monocytogenes-OVA.We have shown that as early as 2 days after infection, very early memory precursors can be identified by their expression of the chemokine receptor CXCR5. These early precursors, which have an effector phenotype, expand and temporarily migrate to the junction of T-cell and B-cell zones, where they interact with follicular CD4 T cells (Tfh) then lose their CXCR5 expression.Remarkably, this interaction with Tfh, hitherto considered as exclusive B-cell helpers, is required for memory precursors to become competent memory cells responsive to IL-21 and capable of mounting efficient cytotoxic secondary effector responses.This study thus unveils critical early steps in the generation of CD8 memory, identifies CXCR5 as the earliest known marker of CD8 memory precursors, reveals a major helper role for Tfh, and points to possible coordination, through Tfh, between the pathways of CD8 and B-cell memory generation. These findings may have implications for vaccine and immunotherapy design
24
Aoki, Nobuhiro. "Dysregulated generation of follicular helper T cells in the spleen triggers fatal autoimmune hepatitis in mice". Kyoto University, 2011. http://hdl.handle.net/2433/142096.
25
CAMPOS, Patrícia Isabel Figueiredo. "Characterization of T follicular helper (Tfh) cells and B cell isotype switching induced by type 1 and type 2 adjuvants". Master's thesis, Instituto de Higiene e Medicina Tropical, 2016. http://hdl.handle.net/10362/20059.
Abstract (sommario):
A principal função dos linfócitos T CD4+ é fornecer apoio a outras células no sentido de gerar uma resposta imunitária eficiente. As interações entre as células T e B são essenciais para a produção de respostas humorais, sendo que foi recentemente demonstrado que as células T foliculares auxiliares (Tfh) desempenham um papel crucial neste processo. Caracteristicamente, expressam o fator de transcrição Bcl-6, o recetor de quimiocinas CXCR5 e o marcador de superfície PD-1. A expressão destes marcadores é única e fundamental para que estas células possam aceder ao folículo de células B, onde orientam as reações no centro germinativo (GC), levando à consequente mudança de isótipo, maturação da afinidade, produção de anticorpos de alta afinidade e células B de memória.
Neste projeto, foram testadas duas hipóteses opostas no sentido de caracterizar fenotipicamente as células Tfh. Propomos investigar se estas são especializadas no fornecimento de auxílio do tipo Th1 ou Th2, que designamos de células hipotéticas "Tfh1" e "Tfh2" (Hipótese 1) ou se são uma subpopulação genérica que responde igualmente na presença de diferentes antigénios, células Tfh (Hipótese 2).
Deste modo, murganhos C57BL/6J e Balb/c foram imunizados na almofada plantar da pata traseira, utilizando proteína Ovalbumin (OVA) combinada com diferentes tipos de adjuvantes: CpG ODNs isoladamente e em combinação com TiterMax® Gold (TMX), Sigma Adjuvant System (SAS) e Montanide ISA 720 VG, testados como adjuvantes tipo 1, e por sua vez Incomplete Freund’s Adjuvant (IFA) e Alum experimentados como adjuvantes do tipo 2. A técnica de ELISA permitiu determinar no soro dos murganhos o tipo de resposta gerada, através da medição de imunoglobulinas específicas para OVA (IgG2a para Th1, IgG1 e IgE total para Th2). CpG ODNs e IFA foram considerados como os adjuvantes mais apropriados para induzir respostas Th1 e Th2, respetivamente.
Células T que reconhecem especificamente OVA foram colhidas de murganhos OT-II Rag-/- e DO11.10 Rag-/- e transferidas para murganhos congénicos. De seguida, procedeu-se à imunização tal como descrito acima. Os nódulos linfáticos drenantes foram recolhidos no pico da reação do centro germinativo (11 dias após imunização), assim como as células Tfh específicas para OVA (CD4+CD44+ CXCR5+PD-1+ Thy1.2+Vβ5+Vα2+/DO11.10+) e as células T auxiliares ativadas específicas para OVA (CD4+CD44+CXCR5-PD-1- Thy1.2+Vβ5+Vα2+/DO11.10+).
A caracterização molecular destas populações de células T está a ser analisada através da sequenciação dos seus transcritos pela técnica de RNA-sequencing. Além disso, a expressão de marcadores de Th1 e Th2 em células Tfh foi analisada através de citometria de fluxo e Reação em Cadeia da Polimerase quantitativa por Transcrição Reversa (RT-qPCR). Neste estudo, foi demonstrado que as células Tfh co-expressam Bcl-6 e T-bet e também produzem IFN-γ, quando sensibilizadas com OVA-CpG ODNs, características concordantes com os marcadores fenotípicos de uma célula Tfh e célula Th1. A expressão de Gata-3 (marcador Th2) só foi detetada sob estimulação IFA-OVA, embora em níveis mais baixos do que as determinadas para T-bet.The major function of CD4+ T cells is to provide help to other lymphocytes to mount an efficient immune response. T and B cell interactions are essential for humoral responses and it was recently shown that T follicular helper (Tfh) cells play a crucial role in this process. They characteristically express the transcription factor Bcl-6, chemokine receptor CXCR5 and PD-1. These markers are unique as their expression is pivotal to acquire access to the B cell follicle and drive germinal centre (GC) reactions, leading to isotype switching, affinity maturation, and production of high affinity antibodies and memory B cells. In this project, two competing hypothesis investigating the phenotype of Tfh cells were tested. We propose to dissect whether Tfh cells are specialized in providing Th1 or Th2 help, which we call putative “Tfh1” and “Tfh2” cells (hypothesis 1), or if they are a more generic Th subset that responds equally in the presence of different antigens, which we designate as Tfh cells (hypothesis 2). Therefore, we immunized C57BL/6J and Balb/c mice in the footpad using Ovalbumin (OVA) protein combined with different adjuvant types: CpG ODNs only and combined with TiterMax® Gold (TMX), Sigma Adjuvant System (SAS) and Montanide ISA 720 VG, as type 1 adjuvant, and Incomplete Freund’s Adjuvant (IFA) and Alum as type 2 adjuvants. Using ELISA assays to determine the type of response generated by measuring serum immunoglobulins of distinct clones (OVA-specific IgG2a for Th1 and OVA-specific IgG1 and total IgE for Th2), we considered CpG ODNs and IFA as the most appropriate adjuvants to induce Th1 and Th2 responses, respectively. OVA-specific cells were transferred from OT-II Rag-/- and DO11.10 Rag-/- mice into congenic mice subsequent to immunization as described above. Draining LNs were collected at the peak of the GC reaction (day 11 post-immunization) and OVA-specific Tfh cells (CD4+ CD44+ CXCR5+PD-1+ Thy1.2+Vβ5+Vα2+/DO11.10+) and OVA-specific activated-Th cells (CD4+ CD44+ CXCR5-PD-1- Thy1.2+Vβ5+Vα2+/DO11.10+) were sorted. The molecular signature of these T cell populations is being analysed via RNA-Sequencing. Moreover, the expression of Th1 and Th2 markers on Tfh cells was investigated via flow cytometry and Reverse Transcription quantitative Polymerase Chain Reaction (RT-qPCR). In this study, it could be shown that Tfh cells of mice immunized with OVA-CpG ODNs co-expressed Bcl-6 and T-bet and also produced IFN-γ, both concordant features with the phenotypic markers of a Tfh cell and of a Th1 cell. As for the expression of Gata-3, it has only been detected in mice under IFA-OVA stimulation, even though at levels lower than the ones determined for T-bet.
26
Huber, Johanna Elisabeth [Verfasser], e Dirk [Akademischer Betreuer] Baumjohann. "Human circulating T follicular helper cells during viral infection and autoimmunity / Johanna Elisabeth Huber ; Betreuer: Dirk Baumjohann". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1226092527/34.
27
Miles, Brodie, Shannon M. Miller, Joy M. Folkvord, David N. Levy, Eva G. Rakasz, Pamela J. Skinner e Elizabeth Connick. "Follicular Regulatory CD8 T Cells Impair the Germinal Center Response in SIV and Ex Vivo HIV Infection". PUBLIC LIBRARY SCIENCE, 2016. http://hdl.handle.net/10150/622413.
Abstract (sommario):
During chronic HIV infection, viral replication is concentrated in secondary lymphoid follicles. Cytotoxic CD8 T cells control HIV replication in extrafollicular regions, but not in the follicle. Here, we show CXCR5(hi)CD44(hi)CD8 T cells are a regulatory subset differing from conventional CD8 T cells, and constitute the majority of CD8 T cells in the follicle. This subset, CD8 follicular regulatory T cells (CD8 T-FR), expand in chronic SIV infection, exhibit enhanced expression of Tim-3 and IL-10, and express less perforin compared to conventional CD8 T cells. CD8 T-FR modestly limit HIV replication in follicular helper T cells (T-FH), impair T-FH IL-21 production via Tim-3, and inhibit IgG production by B cells during ex vivo HIV infection. CD8 T-FR induce T-FH apoptosis through HLA-E, but induce less apoptosis than conventional CD8 T cells. These data demonstrate that a unique regulatory CD8 population exists in follicles that impairs GC function in HIV infection.
28
Gu-Trantien, Chunyan. "Gene expression profiling of CD4+ T cells infiltrating human breast carcinomas identified CXCL13-producing T follicular helper cells associated with tertiary lymphoid structures and better patient outcome". Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209474.
Abstract (sommario):
Over the past decade, studies using murine models have led to the demonstration that CD4+ T helper (Th) cells play a critical role in the control of cancer progression. Additional support for their importance comes from the growing body of recent clinical/translational research data demonstrating the importance of tumor-infiltrating T and B lymphocytes in long-term patient survival for various types of cancer, including breast cancer (BC). As the key population coordinating adaptive immune responses, the role(s) played by individual Th subsets in cancer immunity remains largely controversial. The Th1 subset has uniquely been shown to have a clear anti-tumor effect, guiding CD8+ cytotoxic T cells-mediated direct tumor cell lysis through IFN-γ secretion. Although the negative regulatory role played by Treg cells has been extensively studied in cancer, its prognostic value along with that of Th2 and Th17 cells have not been clearly demonstrated in patients. T follicular helper (Tfh) cells, a recently characterized Th subset that plays a primary role in the generation of B cell memory in secondary lymphoid organs, have not been previously described infiltrating solid tumors. The principal objective of this thesis was to perform an in-depth characterization of tumor-infiltrating CD4+ T cells (TIL) and Th subsets in human BC, where very little is currently known.
Using whole genome microarrays, we analyzed the gene expression profiles of TIL relative to their counterparts from the axillary lymph nodes and peripheral blood. Applying a novel approach, we compared TIL profiles with public microarray data for Th subsets, demonstrating: 1) the presence of all major Th subsets (Th1, Th2, Th17, Treg as well as Tfh) in the TIL, 2) the TIL are effector memory rather than central memory cells, 3) the TIL are concomitantly activated and suppressed and 4) TIL from tumors with extensive lymphoid infiltrates are more activated/less suppressed in the TCR/CD3 signaling pathway, producing higher levels and a wider panel of Th cytokines than TIL from minimally-infiltrated tumors.
We also performed in vitro experiments to study tumor microenvironment effects on TIL by treating normal CD4+ T cells from healthy donor blood with primary tumor supernatants (SN). Tumor SN largely reproduces the TIL profile in normal Th cells, totally suppressing their activation and inhibiting their cytokine production. Intriguingly, the highly restricted number of cytokines induced by tumor SN included several tumor-promoting factors, such as IL-8 and TNF. SN from an extensively-infiltrated tumor was found to be less immune-suppressive than SN from minimally-infiltrated tumors. In line with this, TIL from minimally-infiltrated tumors are closer to SN-treated (suppressed) activated donor cells whereas TIL from extensively-infiltrated tumors are more similar to activated cells without SN treatment.
These results led us to further investigate the observed differences between TIL from extensive and minimally-infiltrated tumors. Genes characterizing Th1 and Tfh cells were enriched in the extensively-infiltrated tumors. PD-1hiCD200hi Tfh cells were specifically detected in extensively-infiltrated tumors by flow cytometry and these cells were determined to be the major source of the chemokine CXCL13. Immunohistochemical analysis demonstrated highly-organized tertiary lymphoid structures (TLS) within the tumor, containing a CD4+/CD8+ T cell zone and a B cell zone with reactive germinal centers where Tfh cells and follicular dendritic cells (FDC) are resident. Their presence suggests the origin of an effective memory anti-tumor immune response.
Finally, we generated Tfh- and Th1-specific gene signatures reflecting differences between extensive and minimal TIL and tested their prognostic value in large-patient-scale public data sets. Our Tfh signature predicts better 10-year disease-free survival for all BC subtypes, outperforming the Th1 signature, suggesting that Tfh cells play a more central role than Th1 cells in anti-tumor immunity. CXCL13 is the determinant gene of our Tfh signature, showing particularly strong prognostic power for the HER2+ subtype. Additionally, these signatures also predict a better response to neoadjuvant chemotherapy.
This thesis research has demonstrated that a previously undetected Th subset, Tfh cells, infiltrates solid tumors and shown that their presence signals enhanced anti-tumor immunity.
Durant cette dernière décennie, des travaux menés dans des modèles murins ont permis de mettre en évidence le rôle crucial joué par les lymphocytes T auxiliaires CD4+ (Th) dans le contrôle de la progression des cancers. De plus, de nombreuses études cliniques et/ou translationnelles récentes corroborent ces observations en montrant une corrélation entre l’importance de l’infiltration intra-tumorale par les lymphocytes T et B et la survie à long terme des patients atteints de différents types de cancer, dont le cancer du sein. En tant que chefs d’orchestre de la réponse immune adaptative, les rôles spécifiques des sous-populations des cellules Th restent controversés. Les Th1 sont la seule population exerçant une claire réponse anti-tumorale, qui est liée à la sécrétion d’IFN-γ, une cytokine primordiale à l’action des lymphocytes T cytotoxiques CD8+. Bien que le rôle néfaste des T régulateurs (Treg) a été largement étudié dans le cancer, leur implication pronostique ainsi que celle des Th2 et Th17 n’ont pas encore été clairement démontrées. La présence d’une sous-population de CD4, les T auxiliaires folliculaires (Tfh), cellules clés dans la différenciation des lymphocytes B mémoires au sein des organes lymphoïdes secondaires, n’a jamais été décrite dans les cancers solides. Le but principal de ce travail est de caractériser les sous-populations des lymphocytes T CD4+ infiltrant la tumeur (TIL) en prenant comme modèle le cancer du sein humain. A l’heure actuelle, il existe très peu de données sur les TIL CD4 dans ce type de cancer.
Nous avons d’abord établi le profil génique des TIL en les comparant avec ceux provenant des ganglions axillaires ou du sang périphérique. En appliquant une nouvelle approche, nous avons comparé les profils des TIL avec les données publiques de sous-populations de Th et démontré que :1) toutes les sous-populations de cellules Th (Th1, Th2, Th17, Treg et Tfh) infiltrent la tumeur, 2) les TIL ont un phénotype plus proche de celui des cellules mémoires effectrices que des cellules mémoires centrales, 3) les TIL sont simultanément activés et supprimés et 4) les TIL provenant des tumeurs massivement infiltrées («extensives») par des lymphocytes sont mieux activés et moins supprimés que les TIL des tumeurs peu infiltrées («minimales») dans la voie de signalisation TCR et produisent des cytokines d’une quantité plus élevée et d’une répertoire plus large.
Nous avons également effectué des expériences in vitro pour étudier l’effet de l’environnement tumoral sur les TIL en traitant des CD4 normaux (provenant des donneuses saines) par le surnageant (SN) extrait des tumeurs fraiches. Le SN tumoral induit un profil génique proche de celui des TIL en inhibant l’activation et la production de cytokines de ces cellules stimulées. Curieusement, parmi le peu de cytokines induites par le SN tumoral, des facteurs pro-tumoraux comme IL-8 et TNF sont détectés. Le surnageant provenant d’une tumeur «extensive» est moins immunosuppresseur que ceux des tumeurs «minimales». Conformément, les TIL provenant des tumeurs «minimales» ont un profil génique proche des cellules normales activées et traitées (supprimées) par le SN tumoral tandis que les TIL des tumeurs «extensives» ressemblent aux cellules activées non traitées.
Ces résultats nous avaient guidés à investiguer plus profondément les différences observées entre les TIL des tumeurs «extensives» et «minimales». Les gènes caractéristiques des Th1 et Tfh sont enrichis dans les tumeurs «extensives». Les cellules Tfh PD1hiCD200hi sont spécifiquement détectées par cytométrie de flux dans les tumeurs «extensives» et sont identifiées comme les producteurs principaux de la chimiokine CXCL13. L’examen par immunohistochimie a permis de détecter des structures lymphoïdes tertiaires (TLS) dans la tumeur, composées d’une zone T (CD4 et CD8) et d’une zone B au sein de laquelle se trouve parfois un centre germinatif actif contenant des Tfh et des cellules dendritiques folliculaires (FDC). La présence de ces structures suggère l’origine d’une réponse immune mémoire anti-tumorale.
Finalement, nous avons établi des signatures géniques spécifiques aux Tfh et Th1 et recherché leur impact pronostique dans deux bases de données publiques à grande échelle. Notre signature Tfh est positivement corrélée avec la survie à 10 ans des patientes de tous les sous-types de cancer du sein, et est plus performante que la signature Th1. Ceci suggère que les Tfh pourraient jouer un rôle plus crucial que les Th1 dans la réponse immune anti-tumorale. CXCL13 est le gène déterminant de notre signature Tfh et son expression est fortement associée à une meilleure survie chez les patientes du sous-type HER2+. De plus, ces signatures prévoient également une meilleure réponse à la chimiothérapie néoadjuvante (préopératoire).
Cette étude a démontré qu’une nouvelle sous-population de CD4, les Tfh, infiltre la tumeur solide et leur présence indique l’existence d’une immunité anti-tumorale renforcée.
Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished
29
Durand, Mélanie. "Spécialisation fonctionnelle des cellules myéloïdes mononucléaires humaines dans l’induction des réponses T folliculaire helper". Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB087/document.
Abstract (sommario):
Les cellules T folliculaires helper (Tfh) jouent un rôle central dans la mise en place de réponses humorales efficaces. En effet, les Tfh participent à la sélection des lymphocytes B permettant le développement de lymphocytes B mémoires et d’anticorps de haute affinité. Les Tfh représentent ainsi une cible prometteuse pour la mise en place de nouvelles stratégies thérapeutiques, notamment pour augmenter l’efficacité de la vaccination. Ainsi, il apparaît crucial de mieux comprendre les étapes menant à leur développement, en particulier chez l’Homme. L’initiation de la polarisation Tfh se déroule dans les organes lymphoïdes secondaires et met en jeu les cellules myéloïdes mononucléaires (MMC). Les MMC présentes dans les organes lymphoïdes comprennent les macrophages résidents et trois sous populations de DC résidentes : les cDC1 (CD141+), les cDC2 (CD1c+) et les pDC. Nous nous sommes plus particulièrement intéressés au rôle respectif des sous populations de MMC humaines dans l’induction de la polarisation Tfh. Ainsi, les travaux effectués au cours de ma thèse avaient pour objectifs dans un premier temps d’analyser la capacité des différentes populations de MMC à induire la polarisation Tfh, afin de mettre en évidence de potentielles spécialisations fonctionnelles. Dans un second temps, nous nous sommes concentrés sur les mécanismes moléculaires impliqués dans l’induction par les MMC de la polarisation Tfh. Nous avons montré une spécialisation fonctionnelle des cDC2 et des macrophages des amygdales pour la polarisation Tfh. Toutefois, des différences ont été observées entre les cDC2 et macrophages, puisque les macrophages induisent la sécrétion par les lymphocytes T d’une grande quantité de CXCL13 par rapport au cDC2, qui sont plus efficaces pour induire la production d’IL21. Nous avons pu également montrer que les cDC2 et macrophages sécrétaient des cytokines précédemment identifiées comme ayant un rôle dans l’induction des Tfh telles que IL12p70, ActivinA et TGFβ. Afin de confirmer le rôle de ces cytokines dans la polarisation induite par les MMC d’amygdales, nous avons utilisé des anticorps bloquants dans nos expériences de polarisation T helper. Ainsi, nous avons confirmé le rôle de l’IL12p70, de l’Activin A et du TGFβ dans l’induction des Tfh humains. Nos résultats suggèrent également un rôle de l’Activin A et de TGFβ dans l’induction de la sécrétion de CXCL13, alors que l’IL12p70 serait impliqué dans l’induction de la sécrétion d’IL21. Nos résultats suggèrent aussi l’existence de deux sous populations de Tfh caractérisées soit par l’expression d’IL21 soit par l’expression de CXCL13. Les travaux réalisés au cours de ma thèse enrichissent ainsi les connaissances sur la spécialisation fonctionnelle des sous populations de DC et des macrophages humains, et apportent de nouveaux éléments pour la compréhension de la différenciation des Tfh humainsT follicular helper cells (Tfh) play a key role in the establishment of efficient humoral responses. Indeed, Tfh are involved in B lymphocyte selection allowing the development of high affinity memory B cells and antibodies. Tfh are promising targets for new therapeutic strategies, especially to increase the effectiveness of vaccination. Thus, it is crucial to better understand the stages leading to their development, especially in human. Initiation of Tfh polarisation occurs in secondary lymphoid organs and involves mononuclear myeloid cells (MMC). MMC from secondary lymphoid organs include resident macrophages and three subsets of resident Dendritic Cells (DC): cDC1 (CD141+), cDC2 (CD1c+) and pDC. We were particularly interested in human MMC subsets respective roles in the induction of Tfh polarisation. Thus, the work carried out during my thesis aimed first at analysing the ability of different populations of MMC to induce Tfh polarisation, in order to highlight potential functional specialisations. In a second step, we focused on the molecular mechanisms involved in Tfh polarisation by MMC. We have shown a functional specialisation of cDC2 and tonsillar macrophages for Tfh polarisation. However, differences have been observed between cDC2 and macrophages, since macrophages induce secretion by T cells of a large amount of CXCL13 compared to cDC2, which are more effective in inducing IL21 production. We have also been able to show that cDC2 and macrophages secreted cytokines previously shown to play a role in Tfh induction such as IL12p70, ActivinA and TGFβ. In order to confirm the role of these cytokines in Tfh polarisation induced by tonsil MMCs, we used blocking antibodies in our T helper polarisation experiments. Thereby, we confirmed the role of IL12p70, Activin A and TGFβ in the induction of human Tfh. Our results also suggest a role for Activin A and TGFβ in inducing secretion of CXCL13, whereas IL12p70 would be involved in the induction of IL21 secretion. Besides, our results suggest the existence of two Tfh subsets characterised by expression of either IL21 or CXCL13. The work performed during my thesis broadens the knowledge on the functional specialisation of human DC subsets and macrophages, and provides new insight into the differentiation of human Tfh
30
Gigoux, Mathieu. "The role of inducible costimulator-mediated phosphoinositide 3-kinase activation in the differentiation and function of follicular helper T cells". Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121421.
Abstract (sommario):
Antibodies are crucial components of the adaptive immune arsenal against invading pathogens. Production of high-affinity class-switched antibodies relies on follicular helper T (Tfh) cells, a distinct subset of CD4 helper T cells that migrate into B cell follicles and promote B cell differentiation into plasma cells during germinal center (GC) reactions. The CD28-like costimulatory receptor Inducible Costimulator (ICOS) is expressed on the surface of activated T cells and is crucial for the generation of Tfh cells in mice and humans, but the molecular mechanisms remained unknown. ICOS had been known as a potent activator of phosphoinositide 3-kinase (PI3K), but the role of ICOS-mediated PI3K activation in T cells has been poorly understood. The work presented here is a compilation of two studies that highlight the unique role of PI3K in ICOS-mediated Tfh cell differentiation and function. In the first study, presented in Chapter II, I analyzed a knock-in strain of mice possessing a point mutation in the cytoplasmic tail of ICOS that prevents binding of PI3K (ICOS-YF). I show that ICOS-mediated PI3K activation is crucial for the generation of Tfh cells, and in turn, GC formation, antibody class-switch, and affinity maturation. The ICOS-PI3K axis was crucial for the potentiation of T cell receptor (TCR)-mediated expression of IL-21 and IL-4, key cytokines involved in T cell-mediated B cell help. I also show data that strongly suggests that ICOS and CD28 have differential roles in the multistep process of Tfh cell differentiation, where CD28 is mainly involved in the early expansion of CD4 T cells through non-PI3K signaling mechanisms, while ICOS is involved in the later stages of Tfh cell differentiation in a PI3K-dependent manner. In the study presented in Chapter III, I show that ICOS costimulation enhances TCR-mediated activation of the key translation mediators 4E-BP1 and S6K, in a manner dependent on PI3K. Consistently, I show that the ICOS-PI3K axis enhances the formation of polysomes on IL-4 mRNA. Using an in vitro T-B cell co-culture system, I provide evidence that ICOS mutant CD4 T cells have impaired ability to induce B cell differentiation due to a limited production of IL-4. These findings suggest that ICOS-PI3K signaling facilitates targeted delivery of IL-4 from helper T cells to cognate B cells during T cell-B cell interactions in the GC. Thus, I demonstrate that PI3K is a key downstream signaling component in ICOS signaling during Tfh cell generation. I also show that ICOS-PI3K signaling can alter translational efficiency of pre-existing mRNAs suggesting ICOS' potential role in regulating the function of Tfh cells.Les anticorps sont des composantes cruciales de l'arsenal que le système immunitaire adaptatif utilise contre les pathogènes invasifs. La production d'anticorps de haute-affinité réarrangés par commutation isotypique nécessite l'apport des lymphocytes T auxiliaires folliculaires (Tfh), un sous-type de lymphocytes T auxiliaires CD4+ qui migrent dans les follicules nodules lymphatiques et y promeuvent la différentiation des cellules B en cellules plasmatiques, le tout durant les réactions du centre germinatif (GC). Le récepteur de costimulation de type CD28 Costimulateur Inductible (ICOS) est exprimé sur la surface des cellules T activées et joue un rôle critique dans la génération de cellules Tfh autant chez la souris que l'humain, cependant les mécanismes moléculaires demeurent inconnus. Jusqu'à présent, ICOS était reconnu comme un puissant activateur de la phosphatidyl inositol-3 kinase (PI3K), mais le rôle de l'activation de PI3K médiée par ICOS dans les cellules T demeure mal compris. Le travail présenté dans cette thèse retrace deux études qui décrivent le rôle unique de PI3K dans la fonction et la différentiation des cellules Tfh médiées par ICOS. Dans la première étude, présenté dans le Chapitre II, j'ai analysé une ligné de souris 'knock-in' possédant une mutation ponctuelle dans la région cytoplasmique de ICOS empêchant ainsi la liaison de PI3K (ICOS-YF). Je démontre que l'activation de PI3K médiée par ICOS demeure cruciale pour la génération de cellules Tfh, ainsi qu'en conséquence la formation des GC, la commutation isotypique d'anticorps et la maturation d'affinité. L'axe ICOS-PI3K s'avère critique pour la potentialisation de l'expression médiée par le récepteur de cellules T (TCR) de IL-21 et IL-4, des cytokines clés impliquées dans l'aide aux cellules B médiée par les cellules T. J'illustre également des résultats qui prouvent que ICOS et CD28 exercent des rôles distinct dans le processus complexe de la différentiation des cellules Tfh, où CD28 est principalement impliqué dans l'expansion précoce des cellules T CD4+ par l'entremise de mécanismes de signalisation indépendants de PI3K, tandis que ICOS s'engage plutôt de façon PI3K-dépendante dans les étapes tardives de la différentiation des cellules Tfh. Dans la seconde étude au Chapitre III, je révèle que la costimulation par ICOS augmente l'activation médiée par le TCR de médiateurs clés de la traduction de 4E-BP1 ainsi que S6K de façon dépendante à PI3K. De façon cohérente, je démontre que l'axe ICOS-PI3K augmente la formation de polysomes sur l'ARN messager d'IL-4. En utilisant un système in-vitro de co-culture de cellules T et B, je fourni des preuves que les cellules T CD4+ mutantes pour ICOS ont une capacité détérioré d'induire la différentiation de cellules B due à une production limitée d'IL-4. Ces découvertes suggèrent que la signalisation par ICOS-PI3K facilite l'acheminement dirigé d'IL-4 d'une cellule T auxiliaire à une cellule B apparentée durant une interaction entre les deux types cellulaires dans le GC. En conclusion, je démontre que PI3K est une composante de signalisation clé en aval de la signalisation par ICOS durant la génération de Tfh. De plus, je prouve que la voix ICOS-PI3K peut modifier l'efficacité de traduction d'ARN messager préexistant suggérant un rôle potentiel d'ICOS dans la régulation de la fonction des cellules Tfh.
31
Migliori, Edoardo. "The importance of CD4+ follicular helper T cells and tertiary lymphoid structures in the anti-tumor immune response to breast cancer". Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/258252.
Abstract (sommario):
Breast cancer (BC) is the most common cancer in women. It is a highly heterogeneous disease in terms of histology, therapeutic response and patient outcomes. Early and accurate detection of breast cancer is crucial as the patient prognosis varies greatly depending on the diagnosis of the disease. Patient outcomes have been linked to the presence of tumor infiltrating lymphocytes (TIL) in solid tumors. In human BC, higher TIL infiltration is associated with a better prognosis and also predicts relevant responses to pre-operative chemotherapy. TIL are primarily composed of T cells, albeit around 20% of BC patients (pts) show significant B cell infiltration, and can organize in tertiary lymphoid structures (TLS) located in the peritumoral stroma, which are associated with survival in HER2+ and triple negative BC patients. Further, these studies revealed that CD4+ follicular helper T (Tfh) cells producing CXCL13 were specifically associated with peritumoral TLS. CXCL13 is an important B cell chemoattractant whose function is to recruit B cells to the germinal center (GC) in secondary lymphoid organs and TLS, where they can mature and differentiate into memory or antibody-producing B cells. The principal objective of this thesis project was to investigate the role of CXCL13 and Tfh cells play in the development and/or maintenance of GC-like structures in BC-associated TLS.Further understanding of the factors that promote TLS formation in vivo could provide important insight for treatment decisions in BC. CXCL13 expression was originally identified as an important signal associated with TLS that was predictive for patient outcomes. We investigated factors capable of inducing CXCL13 expression in CD4+ T cells isolated from peripheral blood, using flow cytometry analysis. Treatment with TGFβ1 alone, or together with several cytokines (IL12, IL21, and in particular IL2 blockade), increased CXCL13 expression in activated CD4+ T cells. Similar to our characterization of Tfh TIL in fresh tumor tissues, these CXCL13-producing CD4+ T cells were CXCR5 negative and expressed the Tfh markers PD-1 and ICOS. The positive correlation, in treated cells and fresh TIL, between CXCL13-producing CD4+ T cells and FoxP3-expressing regulatory CD4+ T cells, and the diminished chemokine production upon depletion of the latter population, suggest a possible positive relationship between regulatory CD4+ T cells and CXCL13-producing CD4+ T cells.We then derived a GC-associated B cell gene signature for integration in our previously published Tfh cell gene signature, including CXCL13 gene. The combined GC gene signature was tested for its ability to sensitively detect BC-associated TLS using a qRT-PCR-based assay on two different cohorts, a primary BC set (n=83) and a retrospective series (n=52) of formalin-fixed paraffin-embedded (FFPE) BC tissues. These data revealed a correlation between gene signature expression and the extent of TLS scored by trained pathologists on dual-immunohistochemistry stained (CD3+CD20 for T and B cells, respectively) FFPE tissue sections. In addition, the high GC signature expression predicted better overall and disease-free survival of BC pts in our retrospective BC cohort, as well as in public microarray data.This thesis research has demonstrated that CXCL13-producing CD4+ T cells lacking CXCR5 differentiate and exert their function in IL-2-limited but TGF-β1-rich conditions. Furthermore, we developed a GC-associated gene signature able to detect TLS in BC and predict BC pts better survival.Doctorat en Sciences biomédicales et pharmaceutiques (Médecine)
info:eu-repo/semantics/nonPublished
32
Rouers, Angéline. "Impact de l’infection par le virus de l’immunodéficience humaine sur les populations de lymphocytes T folliculaires helper et les réponses B mémoires". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066497/document.
Abstract (sommario):
La réponse humorale est altérée lors de l’infection par le virus de l’immunodéficience humaine (VIH). Les lymphocytes T CD4+ folliculaires helper (Tfh) sont impliqués dans la maturation des lymphocytes B (LB) dans les organes lymphoïdes secondaires. Mon travail de thèse s’est articulé autour de deux axes complémentaires visant à étudier les Tfh et les réponses B mémoires lors de l’infection par le VIH. J’ai d’abord étudié les Tfh spléniques lors de la phase chronique de l’infection par le VIH. J’ai mis en évidence une augmentation des populations de Tfh dans les rates de patients VIH+. D’autre part l’infection par le VIH a un impact sur le profil transcriptionnel des Tfh de la rate et la production de cytokines impliquées dans la différenciation des LB, suggérant un défaut fonctionnel des Tfh. Parallèlement, la maturation des LB est altérée dans les rates VIH+. Dans le second axe de ma thèse, j’ai étudié les réponses B mémoires anti-VIH dans différentes cohortes de patients VIH+ : Elite controller (EC) contrôlant l’infection sans traitements et des patients VIH+ traités. J’ai mis en évidence que les EC préservent naturellement leurs compartiments B mémoires et que les réponses B mémoires spécifiques du VIH sont maintenues dans le sang de ces patients. Les réponses B mémoires IgG1+ anti-VIH sont majoritaires chez les EC, tandis que les réponses IgG2+ et IgG3+ sont plus rares. Ces travaux permettent une meilleure compréhension de la physiopathologie de l’infection par le VIH en apportant de nouveaux éléments sur la fonctionnalité des Tfh et les réponses B mémoires anti-VIHHIV infection is associated with a defect of humoral response. T follicular helper cells (Tfh) support multiple steps of B cell maturation and antibody production. My work was divided in two complementary axes aiming to characterize Tfh and memory B cell responses in HIV-infected patients.I identified several Tfh populations in HIV+ and HIV- spleens by FACS. These three populations were increased in HIV+ spleen. I also evidenced an impact of HIV infection on transcriptional profile and a compromised production of B cell differentiation-related cytokines by splenocytes from HIV+ donors. These results suggest Tfh functions impairment during HIV-infection. In parallel, we noticed an altered maturation of B cells in HIV+ spleens. In a cohort study, we compared memory B cell responses in the blood of Elite controllers (EC) who naturally control HIV and treated HIV+ patients. I evidenced that EC naturally preserve their memory B cell compartments. In contrast to anti-HIV IgG2 and IgG3 secreting B cells, most EC exhibit a high frequency of anti-HIV IgG1 secreting B cells. My work highlights a defective Tfh differentiation, which might explain why B cell maturation is severely affected in HIV-progressors. The status of HIV-controller seems associated with the presence of an IgG1 B cell memory response. Further work will highlight whether Tfh functions are preserved in EC
33
Trichot, Coline. "Regulation of Human T Helper Cell Diversity : From In Vitro Dendritic Cell-Based Mechanisms to Candidate Biomarkers in Atopic Dermatitis". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS423.
Abstract (sommario):
Le système immunitaire humain est majoritairement commandé par les cellules dendritiques et les lymphocytes T auxiliaires. Lorsque les cellules dendritiques détectent un pathogène, elles vont instruire les lymphocytes T auxiliaires afin qu’ils adoptent le phénotype approprié à la menace rencontrée. Les lymphocytes T auxiliaires peuvent être divisés en plusieurs sous-populations, caractérisées par la production de cytokines spécifiques. Chaque sous-population de lymphocyte T auxiliaire possède des fonctions propres et est impliquée dans l’élimination de pathogènes distincts. Si les réponses des lymphocytes T auxiliaires ne sont pas finement régulées, ils peuvent devenir pathogéniques, et dans ce cas, considérés comme cibles potentielles pour des thérapies. Dans ce contexte, j’ai concentré mon travail de doctorat sur l’étude de la diversité des sous- populations de lymphocytes T auxiliaires et de leur régulation. Premièrement, j’ai démontré que les cellules dendritiques activées par la TSLP sont capables d’induire la polarisation de lymphocytes T folliculaires. Ensuite, j’ai participé à la construction d’un modèle mathématique capable de prédire la réponse lymphocytaire T auxiliaire en fonction de signaux dérivés des cellules dendritiques. Ce modèle nous a permis d’identifier un rôle spécifique pour l’IL-12p70, dépendant du contexte IL-1, dans l’induction d’IL-17F sans IL-17A. Enfin, j’ai monitoré huit populations de lymphocytes T auxiliaires et folliculaires dans le sang périphérique de patients atteints de dermatite atopique traités par Dupilumab, une immunothérapie ciblant la sous-unité alpha du récepteur de l’IL-4 et j’ai pu montré que la diminution du pourcentage de lymphocytes Th17 correlait avec l’amélioration du score clinique EASI. Globalement, mon travail sur la diversité de phénotypes Th apporte une ressource mécanistique importante, avec une potentielle application en immunothérapieHuman immunity is essentially driven by dendritic cells and T helper cells. When dendritic cells detect a pathogen, they will instruct T helper cells to adopt the adapted phenotype for the specific threat encountered. T helper cells are subdivided in multiple subsets, characterized by particular sets of cytokines. Each T helper subset has specific functions and is involved in the clearance of distinct pathogens. If T helper responses are not precisely regulated, they can become pathogenic, in this case T helper pathways can be considered as potential targets for therapy. In this context, I focused my PhD work on studying T helper cell subset diversity and regulation. First, I demonstrated the ability of TSLP-activated dendritic cell to induce T follicular helper cell polarization. Then I participated in building a mathematical model capable of predicting T helper cell response to dendritic-cell derived signals. This model allowed us to identify the specific role of IL-12p70, in an IL-1 context, to induce IL-17F without IL-17A. Finally, I monitered eight T helper and T follicular helper cell populations in peripheral blood from atopic dermatitis patients treated with Dupilumab, an immunotherapy targeting the IL-4 receptor alpha subunit, and was able to show a correlation between decrease of Th17 cell percentage and improvement of EASI clinical score. Overall, my work on Th phenotype diversity provides key mechanistic insight with potential application in immunotherapy
34
Ogbe, Ane Theodora. "Early Growth Response genes 2 and 3 play a role in chronic inflammation pathology and are essential for the differentiation of T follicular helper cells". Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/11214.
Abstract (sommario):
The Early Growth Response genes 2 and 3 (Egr2/3) are zinc finger transcription factors that play an important role in the immune system. These transcription factors have reported functions in T cell receptor signaling, differentiation of effector T cell subsets and the development of lupus-like autoimmune diseases. Using CD2-Egr2-/- Egr3-/- mouse model, I investigate the development of inflammation pathology, differentiation of T follicular helper (Tfh) cells and the formation of germinal centers (GC) following viral challenge within these mice. The onset of inflammation pathology in CD2-Egr2-/- Egr3-/- mice was discovered to correlate with high levels of pro-inflammatory cytokines in the serum and the development of autoimmune diseases as previously reported by Li et al, 2012. Most importantly, a novel role for the Egr2/3 genes in the differentiation of T follicular helper (Tfh) cells was identified. Tfh cells are responsible for T cell dependent antibody immune response in the GC. They support the differentiation of GC B cells into plasma cells producing long lived high-affinity isotype-switched antibodies and memory B cells. Tfh cell differentiation is regulated by Bcl6 however; the regulators of Bcl6 during Tfh differentiation remain largely unknown. We have now discovered that Egr2/3 genes are required for Bcl6 expression during Tfh cell differentiation. In the absence of the Egr2 and 3 genes, Tfh cell differentiation is severely impaired and GC formation and functions were defective in response to Vaccinia Virus Western Reserve strain (VVWR) infection. Further investigation revealed that Egr2 regulated Bcl6 expression in a Tfh-specific manner as adoptive transfer of WT CD4+ T cells into Egr2-/- Egr3-/- mice was able to rescue Bcl6 expression, Tfh differentiation and GC formation. When the molecular mechanism of how Egr2 regulated Bcl6 was investigated, it was uncovered that Egr2 directly bound to the promoter region of Bcl6 gene in CD4 T cells to regulated Bcl6 expression. Indeed constitutive expression of either Egr2 or Bcl6 in CD2-Egr2-/- Egr3-/- CD4+ T cells rescued Tfh cell differentiation and GC formation. Our results inferred that the Egr2/3 genes are essential for Tfh differentiation and GC formation by regulating Bcl6 expression in CD4 T cells under Tfh condition. Our studies thus suggest that the Egr2/3 genes are paramount for minimising immunopathology and are also critical for efficient antibody production by regulating Tfh cell differentiation.
35
Jacquemin, Clément. "Modulation de la balance lymphocytaire T régulatrice et effectrice dans deux modèles de maladies auto-immunes". Thesis, Bordeaux 2, 2013. http://www.theses.fr/2013BOR22050.
Abstract (sommario):
Le respect de l’équilibre entre lymphocytes T effecteurs auto-réactifs et lymphocytes T régulateurs (LTreg) est primordial dans le maintien de la tolérance aux antigènes du soi. Les partenaires cellulaires et les mécanismes moléculaires impliqués dans la rupture de l’équilibre de cette balance ne sont pas ou peu connus dans les maladies auto-immunes. Ainsi, les travaux décrits dans cette thèse portent sur le dérèglement de la balance T effecteurs/ Treg dans deux modèles de maladies auto-immunes chez l’homme: le lupus érythémateux systémique et l’anémie hémolytique auto-immune (AHAI). Nous montrons une augmentation de l’expression de la molécule de costimulation OX40L (CD252, TNFSF4) à la surface des cellules présentatrices d’antigène circulantes et infiltrant les tissus chez les patients lupiques. Cette augmentation est corrélée à l’activité de la maladie chez l’adulte comme chez l’enfant. Elle a pour conséquence l’induction de lymphocytes T effecteurs de type Tfh (T follicular helper) et le blocage des fonctions suppressives des Treg, deux acteurs majeurs dans la physiopathologie du lupus. Dans le second projet, nous montrons une augmentation de la proportion de T8reg circulants chez les patients affectés d’une AHAI à anticorps chauds en phase de rémission. Ces Treg expriment le CD25, le FoxP3 et exercent leur fonction suppressive par un mécanisme faisant intervenir l’IL10. De faibles doses d’IL-2 permettent l’expansion de cette population cellulaire in vitro. Ces résultats apportent de nouvelles connaissances dans la physiopathologie de ces deux maladies et offrent des perspectives thérapeutiques potentiellesRespect of the balance between autoreactive T cells and regulatory T cells (LTreg) is important to maintain tolerance to self-antigens. Cellular partners and molecular mechanisms involved in the disruption of this balance are not or little known in autoimmune diseases.Thus, the work described in this thesis focuses on the disruption of the T effector/ Treg balance in two models of human autoimmune diseases: systemic lupus erythematosus and autoimmune hemolytic anemia (AIHA). We show an increased expression of the OX40L (CD252, TNFSF4) costimulatory molecule at the surface of both circulating and tissues-infiltrating antigen presenting cells in SLE patients. OX40L expression is correlated with disease activity in adults and in children and results in Tfh (follicular helper T) effector cells induction and Treg suppressive functions inhibition, two key mechanisms in the pathogenesis of lupus. In the second project, we show an increase of the circulating T8reg proportion in patients with a warm AIHA in a non-active state. These Treg express CD25, FoxP3 and exert their suppressive function by a mechanism involving IL-10. Low-dose IL-2 allows the expansion of this cell population in vitro. These results provide new insights into the pathophysiology of these diseases and offer potential therapeutic perspectives
36
Nuttens, Charles. "Mécanismes impliqués dans la polarisation des lymphocytes T CD4+ folliculaires et l'initiation de l'immunité muqueuse après immunisation intradermique par un antigène particulaire". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066429/document.
Abstract (sommario):
La nature des cellules dendritiques (DC) engagées lors d'une vaccination conditionne la qualité de la réponse immunitaire adaptative. L'immunisation par la peau est particulièrement efficace car elle cible de nombreuses sous-populations de DC cutanées telles que les cellules de Langerhans (LC). Cependant, les relations entre ces DC et les cellules effectrices associées à la réponse humorale ne sont pas connues. L'objectif de ma thèse est d'identifier les mécanismes cellulaires précoces impliqués dans l'initiation de la réponse humorale, dans un contexte de vaccination intradermique (i.d.) avec un antigène particulaire. En étudiant la distribution spatiale et temporelle des particules synthétiques de PLA adsorbées par la protéine p24 du VIH, nous avons observé leur prise en charge par les DC cutanées mais également par les DC résidentes des ganglions drainant de la peau. Cependant, l'étude de la réponse immunitaire a démontré que seules les cellules cutanées, et en particulier les LC, induisent la polarisation des lymphocytes T CD4+ folliculaires (TFH) et le développement des lymphocytes B sécrétant des IgA. L'immunisation i.d. a également généré l'infiltration de cellules inflammatoires au niveau du site d'injection et du ganglion. En utilisant un modèle murin Ccr2-/-, nous avons démontré que les cellules dépendantes de CCR2+ interfèrent avec la formation des TFH. Enfin, l'étude du micro-environnement ganglionnaire suggère que TNF est favorable à la polarisation des TFH. En conclusion, ces résultats soulignent l'importance de cibler les DC cutanées lors de la vaccination afin de proposer de nouvelles stratégies vaccinalesThe quality of the adaptive immune response to a vaccine is driven by the nature of dendritic cells (DCs) engaged during vaccination. Skin immunization is particularly efficient as it targets the numerous cutaneous DCs, including Langerhans cells (LCs). However, the relationship between DCs and effector cells associated with humoral immunity has not been elucidated. The main objective of my thesis was to identify cellular mechanisms implicated in the initialization of the humoral immune response, in the context of intradermal (i.d.) vaccination with particle-based antigens. In examining the spatial and temporal distribution of synthetic PLA particles adsorbed with the HIV-p24 protein, we observed their uptake by both cutaneous DCs and also skin-draining lymph node (dLNs) resident DCs. However, our immune response study highlighted that only skin cells, and in particular LCs, were able to stimulate polarization of follicular helper T cells (TFH) and the development of IgA-secreting B lymphocytes. I.d. vaccination also induced an inflammatory cell infiltration at both the injection site and in dLNs. Using a Ccr2-/- mouse model, we have shown the CCR2+ dependant cells can interfere in TFH polarization. Finally, the study of the dLN micro-environment suggested TNF can promote TFH formation. In conclusion, these findings highlight the importance of targeting skin DC in vaccination to propose new vaccine strategies
37
El, Sayed Rania. "ROLE OF FDCs AND FDC ACTIVATION IN PROMOTING HUMORAL IMMUNITY INCLUDING RESPONSES TO T-DEPENDENT ANTIGENS IN THE ABSENCE OF T CELLS". VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1927.
Abstract (sommario):
Follicular dendritic cells (FDCs) reside in primary B-cell follicles and in the light zones of germinal centers (GCs) in secondary follicles, where their dendrites interdigitate forming extensive networks intimately interacting with B-cells. In GCs, FDCs can be found at the edges attached to the supporting reticular fibers. They trap and arrange immune complexes (ICs) in vivo and in vitro in a periodic manner with 200–500Å spacing and provide both antigen-specific and non-specific accessory signals to B-cells. FDCs exist in resting and activated states, with two characteristically different phenotypes. In their activated state, FDCs upregulate the expression of accessory molecules and cytokines important in the FDC-B cell interaction in GCs. We sought to determine the mechanisms influencing the transition of FDCs from a resting to an activated state in GCs and their impact on T-cell dependent (TD) and independent (TI)-GC reactions (GCRs). We found that IC-FDC interactions via FDC-FcgammaRIIB induce the upregulation of FDC-FcgammaRIIB, -ICAM-1, and -VCAM-1, at both the protein and mRNA levels. We also reported for the first time the expression of TLR-4 on FDCs. Moreover, engagement of FDC-TLR4 with LPS activated NF-kappaB, up-regulated expression of important FDC-accessory molecules, including FcgammaRIIB, ICAM-1, and VCAM-1, and enhanced FDC accessory activity in promoting recall IgG responses. Moreover, IC-activated FDCs produced IL-6 and FDC-IL-6 promoted GCRs, somatic hypermutation (SHM) and IgG production. Further, we reported that binding of FDCs to collagen coated surfaces induced restoration of their dendritic processes and networks in vitro. In addition, we designed an FDC-supported in vitro model capable of induction and assessment of primary human antibody responses to protein antigens characterized by class-switching and affinity maturation. Uniquely, we generated TI immune responses to TD protein Ags in the complete absence of T cell help in vivo and in vitro. In the presence of FDC-associated second signals such as BAFF and C4BP, FDC- FcgammaRIIB-periodically trapped-ICs induced the production of Ag-specific IgM, GC-development and plasmablast-differentiation in anti-Thy-1-pretreated nude mice. Purified murine and human B cells cultured in vitro with IC-bearing FDCs also showed the production of antigen–specific IgM within just 48 h.
38
Maho, Maud. "Evaluation des effets des traitements par Rituximab versus corticothérapie seule sur la réponse auto-réactive des patients atteints de pemphigus. First-line Rituximab combined with short-term Prednisone versus Prednisone alone for the treatment of Pemphigus (RITUX 3) : a prospective, multicentre, parallel-group, open-label randomised trial Risk factors for short-term relapse in patients with pemphigus treated by Rituximab as first-line therapy Rituximab and corticosteroid effect on Desmoglein specific B cells and T follicular helper cells in patients with Pemphigus Modifications or the transcriptomic profile of autoreactive B cells from pemphigus patients after treatment with Rituximab or standard corticosteroid regimen Long-term increase of Kcnn4 potassium channel surface expression on B cells in pemphigus patients after Rituximab treatment Rituximab is an effective treatment in patients with Pemphigus Vulgaris and demonstrates a steroid-sparing effect Modifications of the BAFF/BAFF-Receptor axis in patients with pemphigus treated with rituximab versus standard corticosteroids regimen. CD11C+ B cells are mainly memory cells prone to differentiate into antibody-secreting cells". Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR132.
Abstract (sommario):
Le pemphigus est une maladie auto-immune spécifique de la peau et des muqueuses provoqué par des auto-anticorps (Ac) spécifiques des desmogléines (Dsg) 1 ou 3. Ces Ac pathogéniques inhibent l'adhésion cellulaire des kératinocytes. Le pemphigus se déclenche par la conjonction d’événements rares impliquant l’émergence puis la coopération de lymphocytes B (LB) et de lymphocytes LT auto-réactifs dans un contexte génétique et environnemental particulier. Jusqu’à présent, la première ligne de traitement du pemphigus était constituée de fortes doses de corticoïdes, qui sont de puissants immunosupresseurs systèmiques. Le Rituximab (RTX), un Ac monoclonal chimérique anti-CD20, constitue une thérapeutique innovante aboutissant à l’élimination des LB. L’étude clinique RITUX 3 a été conçue pour évaluer l’efficacité et l’innocuité du traitement utilisant le RTX associé à une courte corticothérapie dans le traitement de première intention du pemphigus par rapport au traitement de référence par la corticothérapie standard (CS). Dans un premier temps, notre analyse clinico-biologique des patients après 24 mois a démontré que l’utilisation du RTX associé à de la prednisone à court terme en traitement de première intention chez les patients atteints de pemphigus foliacé et vulgaire modéré à sévère est à la fois plus efficace et mieux toléré que le traitement de référence par la prednisone seule (89% de patients versus 34%). Cette efficacité a été confortée à plus long terme après la reconstitution du répertoire lymphocytaire B avec un risque de rechute de 2% à 36 mois. La présence d’une forme sévère de pemphigus au diagnostic (PDAI ≥ 45) et d’un taux d’Ac anti-Dsg à 3 mois supérieur aux valeurs seuils (anti-Dsg1 ≥ 20 ou anti-Dsg3 ≥ 120) sont associés à un risque de rechute précoce de 50%. Ces deux facteurs prédictifs permettent d'identifier un sous-groupe de patients présentant un risque élevé de rechute nécessitant une perfusion d'entretien de RTX au 6ème mois. Dans un deuxième temps, nous avons étudié l’impact des traitements par RTX et par CS chez les patients atteints de pemphigus afin de mieux appréhender la réponse auto-immune. La caractérisation phénotypique des LB auto-réactifs et l’analyse de la fréquence des LB capables de sécréter des immunoglobulines (Ig)G anti-Dsg par une approche ELISPOT a permis d’établir que l’efficacité du traitement par RTX dans le pemphigus semble liée à l’élimination des LB mémoires CD27+IgG+ spécifiques des Dsg. Des LB auto-réactifs Dsg restent détectables après RTX suite à la reconstitution lymphocytaire B, mais ces LB ont un phénotype naïf et non commuté (IgM) et ne secrètent plus d’IgG. En revanche, la persistance des LB auto-réactifs capables de sécréter des IgG anti-Dsg après traitement par CS est certainement à l’origine des rechutes fréquentes. L’analyse de l’expression génique ciblée à l’échelle unicellulaire a démontré qu’initialement, les LB spécifiques des Dsg ont un profil pro-inflammatoire avec l’expression de trois gènes codant pour les interleukines (IL)-1β, IL-12p35 et IL-23p19 et pour le gène de l’IRF5 (Interferon regulatory factor 5) par rapport aux LB non auto-réactifs. Le RTX et la CS ont des effets différents sur l'expression de ces gènes mais les deux réduisent l’expression génique d’IL-1β qui semble jouer un rôle important dans la physiopathologie du pemphigus. Parallèlement, l’analyse transcriptomique puis protéique des LB isolés des patients en rémission complète ou incomplète 6 ans après l’étude RITUX 1 a mis en évidence une augmentation d'expression de KCNN4 (Potassium calcium-activated channel subfamily N member 4) à la surface des LB chez les patients atteints de pemphigus en rémission complète pouvant influencer la maturation des LBPemphigus is an autoimmune disease of the skin and mucous membranes caused by autoantibodies (Ab) specific to desmoglein (Dsg) 1 or 3. These pathogenic Ab inhibit cell adhesion of keratinocytes. The development of pemphigus is associated with the conjunction of many uncommon events involving the emergence and then the cooperation of auto-reactive B cells and T cells link to genetic and environmental factors. Until now, the first line of treatment consisted of high doses of corticosteroids. Rituximab (RTX), an anti-CD20 chimeric monoclonal antibody, is an innovative therapy that results in B cells depletion. The RITUX 3 clinical trial was designed to evaluate the efficacy and safety of RTX combined with a short-course glucocorticoid therapy as a first-line treatment of pemphigus versus the standard treatment with standard corticosteroids (CS). As a first step, our clinico-biological analysis of patients after 24 months has shown that the use of RTX combined with short-term prednisone as a first-line treatment in patients with moderate to severe pemphigus is both more effective and better tolerated than the reference treatment with prednisone alone. Respectively, 89% of patients versus 34% in each group and both pemphigus foliaceus and pemphigus vulgaris patients responded. This efficacy was confirmed in the longer term after reconstitution of the B lymphocyte repertoire with a risk of relapse of only 2% at 36 months. The presence of a severe form of pemphigus at diagnosis (PDAI ≥ 45) and an anti-Dsg Ab level at 3 months above threshold values (anti-DSG1 ≥ 20 or anti-DSG3 ≥ 120) are associated with 50% risk of early relapse. These two predictive factors make it possible to identify a subgroup of patients at high risk of relapse requiring a maintenance infusion of RTX at the 6th month. In a second step, we studied the impact of RTX and CS treatments in patients with pemphigus in order to better understand the autoimmune response. The phenotypic characterization of auto-reactive B cells and the analysis of the frequency of B cells able of secreting anti-Dsg immunoglobulin (Ig) G by an ELISPOT approach demonstrated that the efficacy of RTX treatment in pemphigus seems related to the elimination of IgG-switched Dsg memory B-cells. Dsg specific B cells remain detectable after RTX when B cells return, but these B cells have a naïve and non-switched (IgM) phenotype and no longer secrete IgG. On the other hand, the persistence of self-reactive Dsg B cells capable of secreting IgG anti-Dsg after treatment with CS is certainly at the origin of the frequency of relapses. The unicellular targeted gene expression analysis demonstrated that initially, Dsg-specific B cells have a pro-inflammatory profile with the overexpression of three genes encoding Interleukin (IL) -1β, IL-12p35 and IL-23p19 and for the IRF5 gene (Interferon regulatory factor 5) compared to non-self-reactive B cells. RTX and CS have different effects on the expression of these genes, but both reduce the gene expression of IL-1β, which seems to play an important role in the pathophysiology of pemphigus
39
Gong, Ya-Zhuo. "Role of salivary gland epithelial cells in the differentiation and activation of T lymphocytes in primary Sjögren's syndrome". Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAJ100/document.
Abstract (sommario):
Le syndrome de Sjögren primitif (SJp) est une pathologie auto-immune caractérisée par une sécheresse occulobuccale, un infiltrat lymphocytaire des glandes salivaires, ainsi qu'une production d'auto-anticorps. Les cellules épithéliales salivaires (SGEC) des patients atteints de SSp expriment les molécules impliquées dans les réponses immunitaires et jouent le rôle des cellules présentatrices d’antigènes. Les lymphocytes T folliculaires (LTf) jouent un rôle important en activant les lymphocytes B via la sécrétion d’interleukine (IL)-21. Une augmentation de la proportion de LTf est observée dans le sang des patients ayant un SJp. Nous avons fait l’hypothèse que les SGECs des patients pouvaient induire la différenciation des lymphocytes T naïfs (LTn) en LTf. Nous avons montré que les SGECs sont capables d’induire la différenciation des LTn en LTf via des facteurs solubles tel l’IL-6. La sécrétion d’IL-21 par les LTf nécessite un contact cellulaire impliquant en partie ICOSL.La voie de costimulation OX40/OX40L est impliquée dans plusieurs maladies autoimmunes. Les polymorphismes d’OX40L sont une prédisposent au SJp. Nous avons étudié le rôle pathogène de la voie OX40/OX40L chez les patients SJp. Notre résultats ont montrés une surexpression d’OX40L et d’OX40 dans les glandes salivaires des patients atteint de SJp. Les cocultures des LTn avec les SS SGECs ou contrôle SGECs augmentent l'expression d’OX40 par les LT. Les SS SGECs favorisent la survie et la prolifération des LT via la voie d’OX40/OX40L. Ces résultats démontrent l'implication d’OX40 et d’OX40L dans la pathogénie du SJp et confirment le rôle important des SGECs dans l’épithelite auto-immune du SJpThe primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by dry mouth and dry eyes. Salivary gland epithelial cells (SGECs) of patients with pSS express the molecules involved in immune responses and act as antigen presenting cells. Follicular helper T cells (Tfh) secrete IL-21 whose augmented secretion is a hallmark of several autoimmunediseases. Here we investigated whether SGECs were capable to induce Tfh differentiation. We report that IL-6 and ICOSL expression by SGECs contributes to naïve CD4+ T differentiation into Tfh cells, as evidenced by their acquisition of a specific phenotype, characterized by Bcl-6, ICOS and CXCR5 expression and IL-21 secretion, but also but by their main functional feature: the capacity to enhance B lymphocytes survival. OX40/OX40L interaction is a pivotal costimulatory pathway. Polymorphisms of OX40L are involved in the genetic predisposition to pSS. We therefore investigated the pathogenic role of OX40/OX40L pathway in pSS. We demonstrated that the proportion of circulating CD4+ T cells expressing OX40 was elevated in patients with pSS and correlated with systemic disease activity. In salivary glands of patients with pSS, epithelial cells overexpressed OX40L and the expression of OX40L and OX40 was respectively evidenced on infiltrating B and T cells. Coculture of T cells with SGECs increased the expression of OX40 by CD4+ T cells promoted T cell survival and proliferation through OX40/OX40L interaction. These studies demonstrate emphasizes unknown pathogenic roles of SGECs and suggests that Tfh, IL-21 and OX40L might be therapeutic targets in pSS
40
Le, saos-Patrinos Corentin. "Rôle des lymphocytes T CD4+ folliculaires dans la physiopathologie de la leucémie lymphoïde chronique". Electronic Thesis or Diss., Bordeaux, 2022. http://www.theses.fr/2022BORD0093.
Abstract (sommario):
La leucémie lymphoïde chronique (LLC), leucémie la plus fréquente chez l’adulte, est caractérisée par l’accumulation de petits lymphocytes B matures dans la moelle osseuse, les organes lymphoïdes secondaires et le sang périphérique due à une prolifération anormale et à une résistance accrue à l’apoptose des cellules B. La LLC est d’évolution lente et de pronostic variable ; certains patients sont asymptomatiques alors qu’à l’inverse, d’autres présentent une forme agressive de la maladie associée à des complications potentiellement mortelles. Bien que les altérations génétiques jouent un rôle clé dans la pathogénèse de la maladie, elles ne sont pas suffisantes au développement de la maladie. De nombreuses études ont effectivement démontré que les interactions des B-LLC avec les cellules présentes dans l’environnement tumoral sont essentielles pour leur prolifération et promeuvent leur résistance à l’apoptose. Ainsi, les lymphocytes B-LLC migrent dans les ganglions, et rencontrent des lymphocytes T activés qui favorisent leur prolifération et leur résistance à l’apoptose. De plus, un modèle de transfert adoptif de lymphocytes T CD4+ autologues dans des souris a démontré leur capacité à promouvoir la survie et la prolifération des lymphocytes B-LLC in vivo, mettant en avant le rôle des lymphocytes T dans la pathogénèse de la LLC. Différentes sous populations de lymphocytes T CD4+ coexistent, chacune ayant ses propres caractéristiques phénotypiques et fonctionnelles. Malgré de nombreuses études sur le rôle des LTh dans la LLC, l’implication de chacune des sous-populations dans la pathogénèse de la LLC reste à définir. À titre d’exemple, de grandes quantités plasmatiques d’IFNγ sont détectées dans un modèle murin de LLC, suggérant un rôle des lymphocytes Th1. Par opposition, la progression de la LLC dans un modèle génétique murin, a été démontré comme étant indépendante de cette accumulation de Th1. De plus, de nombreuses études utilisant des modèles murins ou des prélèvements de patients ont également mis en lumière l’implication d’autres sous populations de LTh telles que les lymphocytes Th2 et Th9. Ces résultats controversés peuvent s’expliquer par l’utilisation de différents modèles murins ou d’études chez des patients à différents stades de la maladie, ou sous traitement. Il parait ainsi important d’obtenir une vue d’ensemble du compartiment T chez des patients LLC aux différents stades cliniques de la maladie et de s’affranchir de l’effet des traitements. Pour cela, nous avons réalisé une analyse non supervisée, par cytométrie en flux, sur le sang d’individus contrôles et de patients LLC non traités. Nos résultats ont montré une expansion des lymphocytes T folliculaires helper (Tfh) CXCR5+ qui jouent un rôle critique dans la sélection, la survie et la différenciation des lymphocytes B en cellules B sécrétrices d’anticorps et en lymphocytes B mémoires via leur expression de CD40L et leur production d’IL-21. Ces lymphocytes Tfh de patients LLC sont PD1+IL-21+IFNγ+ et donc orientés vers un phénotype Th1 et activés. L’accumulation des Tfh est positivement corrélée avec le stade clinique de la maladie et négativement corrélée avec les taux sériques d’IgG et d’IgA, l’hypogammaglobulinémie étant un facteur de risque de complications infectieuses. De plus, une corrélation existe entre le nombre de Tfh et la charge tumorale, représentée par le nombre de lymphocytes B malins circulants. Finalement, nous avons montré que les lymphocytes Tfh sont capables d’induire la prolifération des lymphocytes B-LLC in vitro, par un mécanisme dépendant de l’IL-21 mais indépendant de l’IFNγ. Nos données démontrent donc un rôle des lymphocytes Tfh dans la progression de la maladieChronic lymphocytic leukemia (CLL), one of the most common adult leukemia, is associated with variable outcomes, ranging from patients who have a stable disease with a nearly normal life expectancy to patients with a progressive disease and severe complications that ultimately lead to a poor survival. CLL is defined by the accumulation and proliferation of mature CD5+ B-lymphocytes in the bone marrow, peripheral lymphoid organs and blood. Although genetic alterations play a key role in CLL pathogenesis and support malignant transformation of B cells, multiple studies have demonstrated that interactions of CLL B cells (B-CLL) with accessory cells are essential for B-CLL proliferation and promote their resistance to apoptosis. Particularly, B-CLL follow chemokine gradients into lymph nodes (LN) where they organize into proliferation centers in which they encounter activated T cells, which further support their growth by increasing their resistance to apoptosis. Moreover, adoptive transfer of autologous CD4+ T cells into mice was demonstrated to promote B-CLL survival and proliferation in vivo highlighting the key role of T cells in B-CLL pathogenesis. Different CD4+ T cell subsets coexist, with each having their own phenotype and functions. Despite numerous studies addressing the role of T helper (Th) cells in CLL, the implication of each individual CD4+ T cell subset in CLL pathogenesis is still under debate. As an example, large amount of IFNγ were detected in the plasma of CLL-bearing animals, suggesting a role of Th1. Conversely, CLL progression in a genetic mouse model of the disease was reported to be independent of Th1 cells. In addition to multiple studies using either patient samples or mouse models of CLL have implicated Th2/Th9 CD4+ T cell subsets in disease progression as well. The conflicting results regarding CD4+ T helper subsets involved in CLL pathogenesis might be due to studies performed in different mouse models of the disease and using patient samples from different disease stages. Therefore, we thus performed an unsupervised study by flow cytometry on peripheral blood from control individuals and untreated CLL patients to get snapshots of the T cell compartment across the disease spectrum. Our results showed an increase in the CXCR5+ T follicular helper cells (Tfh) population, a subset playing a critical role in mediating the selection, survival and differentiation of B cells into antibody secreting cells and memory B cells through the expression of CD40L and IL-21 production. Importantly Tfh from CLL patient were skewed toward an activated Th1-profile as evidenced by their PD1+IL-21+IFNγ+ phenotype. The highest accumulation of Tfh cells was observed in advanced stages of the disease and Th1-like Tfh levels inversely correlated with serum IgG and IgA levels, decreased Ig levels being a risk factor for infectious complications. We were also able to uncover a correlation between the number of Tfh cells and the tumor burden represented by the number of circulating malignant B cells. Finally, we showed that Tfh cells effectively induce B-CLL proliferation in an IL-21 dependent but IFNγ independent mechanism. Our data therefore support the involvement of Tfh cells in CLL disease course
41
Vaineau, Romain. "Impact of IL-1β on Tfh and Tfr lymphocytes during physiological and pathological germinal center reaction". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS504.
Abstract (sommario):
Les lymphocytes T folliculaires auxiliaires (Tfh) et régulateurs (Tfr) orchestrent la réaction de centre germinatif (GC) en contrôlant la maturation des lymphocytes B. L'équilibre entre ces cellules est crucial pour la production d'anticorps de haute affinité; sa perturbation peut induire l'auto-immunité, mettant en exergue l'importance des mécanismes régulateurs essentiels. L'interleukine-1β (IL-1β), une cytokine pro-inflammatoire connue, attire l'attention. Son rôle précis est bien documenté dans le cadre de l'immunité innée grâce au récepteur agoniste IL-1R1 et au récepteur leurre IL-1R2 qui séquestre l'IL-1β. Cependant, son interaction spécifique avec les Tfh et Tfr reste à approfondir. Cette étude, en dépassant les limites des travaux jusqu'alors confinés aux modèles murins, vise à éclairer l'interaction dynamique entre l'IL-1β et ces lymphocytes. Notre approche novatrice, empruntée à l'immunologie des systèmes, implique l'étude de divers organes lymphoïdes secondaires humains représentant des phases distinctes de maturation des Tfh et Tfr. Nous avons identifié des profils différentiels liés aux récepteurs à l'IL-1β démontrant l'hétérogénéité des Tfr, et l'inférence de trajectoire prédit une bifurcation des lymphocytes GC-Tfh vers certains Tfr. L'expression de l'IL-1R1 est associée à la maturation des Tfh, et son excès par rapport à l'IL-1R2 précipite leur transition vers un phénotype Tfr singulier en contraste avec celui décrit chez la souris. Le séquençage d'ARN en cellule unique et l'immunophénotypage confirment la sensibilité des Tfh et Tfr à l'IL-1β, qui optimise leur fonction cellulaire. Une analyse de cohorte révèle une corrélation entre la signalisation altérée de l'IL-1β et les anomalies des réponses Tfh et Tfr dans l'auto-immunité. En somme, nous proposons un rôle pivot de l'IL-1β dans la dynamique des lymphocytes Tfh et Tfr à travers le jeu d'expression des récepteurs à l'IL-1, illustrant son impact sur les réponses anticorps induites par le GC. Cette étude ouvre des pistes innovantes pour mieux comprendre et traiter les maladies auto-immunesT follicular helper (Tfh) and T follicular regulatory (Tfr) cells orchestrate the germinal center (GC) reaction by providing balance to B cell maturation. The harmonious interplay between Tfh, Tfr and B cells fosters high affinity antibody production, while its dysregulation can yield to autoimmunity, highlighting the importance of the underlying regulatory mechanisms. In this context, the role of Interleukin-1β (IL-1β) emerges as a focal interest. This proinflammatory cytokine is well-documented in modulating innate immune responses through the agonist receptor IL-1R1 while IL-1R2 exerts a decoy function by sequestering IL-1β. However, its specific interaction with Tfh and Tfr is not fully elucidated. This study embarks on a critical exploration of IL-1β's influence on the dynamic equilibrium of Tfh and Tfr, transcending the limitations of previous studies predominantly confined to murine models. Here, we carry an original systems immunology approach encompassing the use of varied human secondary lymphoid organs that embody distinct stages of Tfh and Tfr maturation. We reveal differential patterns of IL-1 receptors that govern Tfr heterogeneity, and trajectory inference predicts a bifurcation branching out from GC-Tfh. IL-1R1 expression is associated to Tfh maturation, and its excess over IL-1R2 precipitates the transition to a unique Tfr phenotype contrasting with the one described in mice. The application of single-cell RNA sequencing together with immunophenotyping confirmed Tfh and Tfr responsiveness to IL-1β, which promotes their functionality. A patient cohort suggested a tangible link between dysregulated IL-1β signaling and pronounced aberrancies in Tfh and Tfr responses during autoimmune pathogenesis. Collectively, our findings underscore IL-1β’s pivotal role in Tfh and Tfr cell dynamics through the interplay of IL-1 receptors, unveiling its influence on GC-mediated antibody responses. This study offers new insights into autoimmune disease mechanisms and potential interventions
42
Marschall, Pierre. "Etude de la fonction des cellules dendritiques dans la réponse immunitaire cutanée de type 2". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAJ044.
Abstract (sommario):
La dermatite atopique (AD) est une des maladies inflammatoires chroniques cutanée les plus fréquentes qui affecte jusqu'à 20% des enfants et 3% des adultes dans le monde. Elle se caractérise par une inflammation chronique de la peau et des réponses immunitaires humorale et de type 2. Mon travail de thèse est d'étudier le rôle des cellules dendritiques (DCs) dans la génération des lymphocytes T et la pathogenèse de l'AD. Dans la partie I, à l'aide de deux modèles murins d'AD, l'un déclenché par la surexpression de TSLP dans la peau induite par l'application topique de MC903 et l'autre par sensibilisation à un allergène à travers une peau dont la barrière épidermique est lésée, nous montrons le rôle crucial joué par TSLP dans la différentiation des lymphocytes T auxiliaires folliculaires (Tfh) et le développement des centres germinatifs (GC). Nous établissons le rôle contradictoire des cellules de Langerhans dans la réponse Tfh/GC promue par TSLP. Dans la partie II, nous montrons que, en plus de son implication dans la réponse Th2, TSLP signale par son récepteur TSLPR à la surface des DCs pour induire la différentiation des lymphocytes Tregs ST2+ dans le ganglion drainant. De plus, la différentiation de ces cellules implique OX40L, molécule de costimulation exprimée par certaines DCs migratoires, suggérant que l'axe TSLP-TSLPRDC-OX40L joue un rôle non reconnu dans l'induction des lymphocytes Tregs ST2+ dans le cadre de l'ADAtopic dermatitis (AD) is a one of the most common chronic inflammatory skin disease which affects up to 20% of children and 3% of adults worldwide, with increasing prevalence in the industrialized countries during the last 30 years. It is characterized by chronic cutaneous inflammation, humoral and T helper type 2 (Th2) responses. My PhD study is to investigate the role of skin dendritic cells (DCs) in the generation of T helper cells in the pathogenesis of AD. In the Part I, using two mouse models of AD, one triggered by the overexpression of TSLP in mouse skin through topical application of MC903, and the other one with epicutaneous allergen sensitization on barrier-disrupted skin, we demonstrated a crucial role of TSLP in promoting T follicular helper (Tfh) cell differentiation and germinal center (GC) response. We uncovered a seemingly contradictory role of Langerhans cells in TSLP-promoted Tfh/GC response. In the part II, we showed that, in addition to promote Th2 cell differentiation, TSLP signals through TSLPR expressed by DCs to induce the differentiation of ST2+ Tregs in skin-draining lymph nodes. Interestingly, the differentiation of these cells implicates OX40L, a costimulatory molecule expressed in a subset of migratory DCs, suggesting a previously unrecognized role of TSLP-TSLPRDC-OX40L axis in the induction of ST2+ Tregs in AD pathogenesis
43
Powell, Michael D. "Insights Into the Regulatory Requirements for T Follicular Helper Cell Development". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/89085.
Abstract (sommario):
During the course of an immune response, CD4+ T helper cells differentiate into a number of subsets including: T helper 1 (TH1), TH2, TH17, and T follicular helper (TFH) populations. The functional diversity of CD4+ T effector cells results in a coordinated, pathogen-specific immune response. For example, the production of IFNγ by TH1 cells is vital for the clearance of intracellular pathogens, while TFH cell engagement with cognate B cells is required for germinal center (GC) formation and the generation of pathogen- and vaccine- induced antibody production. The development of CD4+ subsets is contingent on extracellular signals, in the form of cytokines, and downstream transcriptional networks responsible for promoting the unique gene expression profile for each subset while simultaneously suppressing alternative cell fates. However, the exact composition of, and stage-specific requirements for, these environmental cytokines and transcription factor networks in the governance of TFH cell differentiation remain incompletely understood. The work in this dissertation seeks to understand how cell-extrinsic cytokine signals and cell-intrinsic transcription factor activities are integrated to properly regulate TFH cell development. Here, we demonstrate that in response to decreased IL-2 and constant IL-12 signaling, T helper 1 (TH1) cells upregulate a TFH-like phenotype, including expression of the TFH lineage defining transcription factor Bcl-6. Intriguingly, our work established that signals from IL-12 were required for both the differentiation and function of this TFH-like population. Mechanistically, IL-12 signals are propagated through both STAT3 and STAT4, leading to the upregulation of the TFH associated genes Bcl6, Il21, and Icos, correlating with increased B cell helper activity. Conversely, exposure of these TFH-like cells to IL-7 results in the STAT5-dependent repression of Bcl-6 and subsequent inhibition of the TFH phenotype. Finally, we describe a novel regulatory mechanism wherein STAT3 and the Ikaros zinc finger transcription factors Ikaros and Aiolos cooperate to regulate Bcl-6 expression in these TFH-like cells. Collectively, the work in this dissertation significantly advances our understanding of the regulatory mechanisms that govern TFH cell differentiation, setting the basis for the rational design of novel immunotherapeutic strategies and increasingly effective vaccines.Ph. D.
Specialized cells called T helper cells serve as a critical interface between the innate (first line of defense) and adaptive (specialized and long-term) immune systems. During the course of an infection, T helper cells are responsible for orchestrating the immune-mediated elimination of invading viruses, bacteria, and parasites. This wide breadth of functionality is achieved through the formation of distinct T helper subsets including T helper 1 (TH1), TH2, TH17, and T follicular helper (TFH) populations. Individual subsets have distinct developmental requirements and have unique functions within the immune system. For example, TFH cells are required for the production of effective antibodies that recognize invading pathogens, leading to their subsequent elimination. This naturally occurring process is the basis for a number of modern medical therapies including vaccination. Conversely, aberrant generation of antibodies that recognize host tissues can result in the onset of various autoimmune diseases including lupus, multiple sclerosis, and crohn’s disease. Due to the importance of TFH cells to human health, there is intense interest in understanding how these cells are formed. It is recognized that the generation of these therapeutically important immune cells is mediated by numerous cell-extrinsic andintrinsic influences, including proteins in their cellular environment called cytokines, and important proteins inside of the cell called transcription factors. However, as this is a complicated and multi-step process, many questions remain regarding the identity of these cytokines and transcription factors. The work in this dissertation seeks to understand how cellextrinsic cytokine signals and cell-intrinsic transcription factor activities are integrated to properly regulate TFH cell development. Collectively, this body of work significantly advances our understanding of the regulatory mechanisms that govern TFH cell differentiation, setting the basis for the rational design of novel immunotherapeutic strategies and increasingly effective vaccines.
44
Renand, Amédée. "La neuropiline 1 et le récepteur alpha à l’IL-2 (CD25) : expression et implication dans l’homéostasie des lymphocytes T chez l’homme dans un contexte normal ou pathologique". Thesis, Paris 11, 2011. http://www.theses.fr/2011PA11T032/document.
Abstract (sommario):
Des études récentes ont montré une implication de la neuropiline 1 (Nrp1)dans le contrôle de l’activation des lymphocytes T. Son invalidation s’accompagne d’une aggravation de l’encéphalite auto-immune expérimentale (EAE). La sémaphorine 3A (Sema-3A), ligand principal de la Nrp1, semble participer à une boucle autocrine de rétro contrôle négatif de la prolifération des lymphocytes T.Cependant, peu d’études ont été réalisées chez l’homme pour déterminer dans quelle(s) situation(s) la Nrp1 est exprimée par les lymphocytes T. Notre travail aconsisté à étudier l’expression de la Nrp1 par les populations lymphocytaires T humaines afin de comprendre à quel niveau peut avoir lieu ce rétro contrôle. Nous montrons que les lymphocytes T régulateurs (Treg) chez l’homme n’expriment pas laNrp1, contrairement aux Treg murins. En revanche, la Nrp1 est exprimée par les lymphocytes T effecteurs après engagement avec l’antigène, soit au niveau des organes lymphoïdes secondaires pour les lymphocytes T folliculaires helper (Tfh) en interaction avec les lymphocytes B, soit au niveau des sites d’inflammations périphériques pour les lymphocytes T effecteurs mémoires (TEM). Dans les deux cas, cette expression survient en fin d’activation et pourrait servir de frein à une activation incontrôlée des lymphocytes T.D’autre part, nous avons abordé le rôle du récepteur alpha à l’IL-2 (CD25)dans l’homéostasie des lymphocytes T. L’étude chez la souris il2ra-/- a révélé un rôle important du CD25 pour la survie des Treg in vivo, mais aussi pour l’acquisition de lymphocytes T mémoires. Seulement deux cas de déficience en CD25, associés à des maladies auto-immunes, ont été décrits chez l’homme. Cependant, ces études n’ont pas abordé à quel niveau le CD25 intervient sur l’homéostasie des lymphocytes T. Nous complétons ces études par la présentation de trois nouveaux cas de déficience en CD25 développant des maladies auto-immunes de type IPEX. Nous montrons que le CD25 intervient activement dans le maintien des populations Treg naïves et effectrices, mais aussi dans celui des populations lymphocytaires effectrices mémoiresRecent studies have shown the involvement of neuropilin 1 (Nrp1) in the control of T cell activation, and disruption of this receptor promotes aggravation of experimental autoimmune encephalitis (EAE). Through its principal ligand,semaphorin 3A (Sema-3A), Nrp1 appears to participate in an autocrine negative feedback of T cell proliferation. However, few studies have been conducted inhumans to determine when Nrp1 is expressed by T cells. Here we show that regulatory T cells (Treg) in humans do not express Nrp1, unlike murine Treg cells. In contrast, we show that Nrp1 is expressed by effector T cells after engagement with antigen, either in secondary lymphoid organs for follicular helper T cells (Tfh) interacting with B cells, either in peripheral inflammation for effector memory T cells(TEM). We conclude that this expression corresponds to a level of late activation in both cases and may control T cell activation.The study in mice il2ra-/- revealed a significant role of IL-2 receptor alpha(CD25) for the survival of Treg in vivo, but also for the differentiation of memory T cells. Only two cases of CD25 deficiency associated with autoimmune diseases have been described in humans. However, these studies do not assess at what levelCD25 is involved in T cell homeostasis. Here we provide further insight of these studies by presenting three new cases of CD25 deficiency developing autoimmune diseases like IPEX. We show that CD25 plays an active role to maintain naive and effector Treg cell populations of, and effector memory T cell populations
45
Levin, Clément. "Mécanismes moléculaires et cellulaires dans l’induction des réponses T helper folliculaires après vaccination cutanée". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066480/document.
Abstract (sommario):
La vaccination du tissu cutané présente un fort potentiel, car elle permet le ciblage de l’antigène aux populations de cellules dendritiques uniques et spécialisées de la peau, et le recrutement de cellules inflammatoires du sang.Les cellules T helper folliculaires (TFH) jouent un rôle crucial dans l’établissement de la réponse humorale. Cependant, les interactions cellulaires et moléculaires qui gouvernent leur induction dans un contexte de vaccination restent à élucider.Mon projet de thèse a eu pour but de mieux comprendre les mécanismes d’induction des réponses TFH et humorales, par l’étude des événements précoces ayant lieu aux sites d’immunisation et d’induction de l’immunité adaptative après vaccination cutanée. L’utilisation de modèles murins nous a permis d’évaluer la contribution de différentes populations de la peau, du ganglion, et du sang dans la mise en place de ces réponses après immunisation intradermique avec un antigène particulaire présentant l’antigène modèle p24 du VIH. Cette étude a révélé un rôle crucial des cellules de Langerhans et des cellules dendritiques migratoires de la peau dans l’induction de réponses TFH et humorales.Nous avons ensuite évalué la capacité de différentes formulations d’adjuvants à polariser la réponse TFH et humorale contre un antigène de l’enveloppe du VIH à fort potentiel vaccinal. L’utilisation de l’émulsion IFA favorise l’induction des cellules TFH et induit la production d’anticorps neutralisants des souches du VIH.Ces résultats soulignent l’importance de cibler les DCs de la peau par l’utilisation de voies de vaccination pertinentes et l’utilisation d’adjuvants capables de favoriser la réponse cellulaire TFHSkin vaccination is of great interest, as it enables targeting of the antigen to unique and specialized dendritic cell populations of the skin, as well as recruitment of inflammatory blood cells.T follicular helper (TFH) cells play a critical role in the setting of the humoral response. However, the cellular and molecular interactions that underlie their induction after vaccination remain unknown.My thesis project aimed at understanding the immune mechanisms by which skin vaccination could favor the induction of TFH and humoral immune responses by studying the early events that take place in tissue and lymph node.Using mice models, we evaluated the relative contributions of various populations from the skin, lymph node and blood in the setting of TFH cell responses after intradermal immunization with nanoparticles coated with p24 antigen from HIV. This revealed a crucial role of Langerhans cells and skin migratory dendritic cells in the induction of TFH and germinal center responses.We then evaluated the ability of different adjuvant formulations to polarize the TFH and humoral response against a promising vaccine antigen from HIV envelope protein. Emulsifying the antigen in IFA favors the induction of TFH cells and induces the production of neutralizing antibodies able to block viral infection.This work highlights the relevance of targeting skin dendritic cells by using relevant vaccination routes and adjuvant formulation able to induce TFH cell responses
46
Bin, Sofia <1990>. "Erythropoietin reduces pathogenic humoral immunity by inhibiting T Follicular Helper cell differentiation and function". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9694/1/TesiPhD_SofiaBin_Final.pdf.
Abstract (sommario):
A large fraction of organ transplant recipients develop anti-donor antibodies (DSA), with accelerated graft loss and increased mortality. We tested the hypothesis that erythropoietin (EPO) reduces DSA formation by inhibiting T follicular helper (TFH) cells.
We measured DSA levels, splenic TFH, TFR cells, germinal center (GC), and class switched B cells, in murine models of allogeneic sensitization, allogeneic transplantation and in parent-to-F1 models of graft versus host disease (GVHD).
We quantified the same cell subsets and specific antibodies, upon EPO or vehicle treatment, in wild type mice and animals lacking EPO receptor selectively on T or B cells, immunized with T-independent or T-dependent stimuli.
In vitro, we tested the EPO effect on TFH induction. We isolated TFH and TFR cells to perform in vitro assay and clarify their role.
EPO reduced DSA levels, GC, class switched B cells, and increased the TFR/TFH ratio in the heart transplanted mice and in two GVHD models.
EPO did also reduce TFH and GC B cells in SRBC-immunized mice, while had no effect in TNP-AECM-FICOLL-immunized animals, indicating that EPO inhibits GC B cells by targeting TFH cells. EPO effects were absent in T cells EPOR conditional KO mice, confirming that EPO affects TFH in vivo through EPOR.
In vitro, EPO affected TFH induction through an EPO-EPOR-STAT5-dependent pathway.
Suppression assay demonstrated that the reduction of IgG antibodies was dependent on TFH cells, sustaining the central role of the subset in this EPO-mediated mechanism.
In conclusion, EPO prevents DSA formation in mice through a direct suppression of TFH. Development of DSA is associated with high risk of graft rejection, giving our data a strong rationale for studies testing the hypothesis that EPO administration prevents their formation in organ transplant recipients. Our findings provide a foundation for testing EPO as a treatment of antibody mediated disease processes.
47
Boyden, Alexander Wiser. "Influenza A virus induces regulated T cell-driven B cell responses". Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3432.
Abstract (sommario):
Protection from influenza A virus (IAV) challenge requires switched, high affinity Abs derived from long-lived memory B cells and plasma cells. These subsets are generated in germinal centers (GCs), hallmark structures of T helper cell-driven B cell immunity. A full understanding of the acute and persistent GC B cell reaction following respiratory IAV infection is lacking, as is the characterization of IAV-induced T follicular helper (TFH) cells that support GCs. Additionally, it remains unclear as to whether IAV-induced GC B cells are subject to control by regulatory T cells (Tregs). To address this, GC B cell and TFH cell responses were analyzed in mice following pulmonary challenge with IAV. Studies demonstrated that marked GC reactions were induced in lung-draining lymph nodes (dLNs), lung, spleen and nasal-associated lymphoid tissue (NALT), although the magnitude, kinetics, and isotype switching patterns of the response was site-specific, and largely depended on the magnitude of IAV-induced TFH cell populations. TFH cell magnitude peaked prior to that of GC B cells in all tissues, and TFH cells purified from dLNs generated IL-21 and IFN-gamma upon activation, although CD4+CXCR5- T effector cells produced higher levels of all cytokines. IgA+ GC B cells were infrequent in most sites, but composed a significant subset of the switched GC population in NALT. Further, splenectomized mice withstood a lethal recall challenge, suggesting the spleen to be unnecessary for long-term protection. Additionally, GC B cell populations were analyzed at distal time points to assess the understudied, persistent GC B cell response after IAV infection. Our analysis demonstrated that persistent GC B cell populations in mouse lungs directly correlated with infectious dose, pathogenicity of the virus, as well as the presence of long-term CD4+ T cell help. Finally, experiments showed that Tregs contribute to the control of GCs induced in the spleen by IAV challenge. This was demonstrated by a marked increase in the number of total and switched GC B cell numbers when Tregs were either depleted or disrupted in vivo proximal to IAV exposure.
48
Suhail, Tahir. "A CD153+ CD4+ T follicular cell population with cell-senescence features plays a crucial role in lupus pathogenesis via osteopontin production". Kyoto University, 2015. http://hdl.handle.net/2433/202671.
49
Rydyznski, Carolyn E. "Natural Killer Cell Regulation of Humoral Immunity". University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535377157934852.
50
Wang, Ling, Dechao Cao, Ling Wang, Juan Zhao, Lam Nhat Nguyen, Xindi Dang, Yingjie Ji et al. "HCV-associated Exosomes Promote Myeloid-Derived Suppressor Cell Expansion via Inhibiting miR-124 to Regulate T Follicular Cell Differentiation and Function". Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/6524.
Abstract (sommario):
Virus-infected cells can regulate non-permissive bystander cells, but the precise mechanisms remain incompletely understood. Here we report that this process can be mediated by transfer of viral RNA-loaded exosomes shed from infected cells to myeloid-derived suppressor cells (MDSCs), which in turn regulate the differentiation and function of T cells during viral infection. Specifically, we demonstrated that patients with chronic hepatitis C virus (HCV) infection exhibited significant increases in T follicular regulatory (TFR) cells and decreases in T follicular helper (TFH) cells. These MDSC-mediated T-cell dysregulations resulted in an increased ratio of TFR/TFH and IL-10 production in peripheral blood. Specifically, co-culture of MDSCs derived from HCV patients with healthy peripheral blood mononuclear cells (PBMCs) induced expansion of TFR, whereas depletion of MDSCs from PBMCs of HCV patients reduced the increases in TFR frequency and IL-10 production, and promoted the differentiation of IFN-γ-producing TFH cells. Importantly, we found that exosomes isolated from the plasma of HCV patients and supernatant of HCV-infected hepatocytes could drive monocytic myeloid cell differentiation into MDSCs. These exosomes were enriched in tetraspanins, such as CD63 and CD81, and contained HCV RNA, but exosomes isolated from patients with antiviral treatment contained no HCV RNA and could not induce MDSC differentiation. Notably, these HCV RNA-containing exosomes (HCV-Exo) were sufficient to induce MDSCs. Furthermore, incubation of healthy myeloid cells with these HCV-Exo inhibited the expression of miR−124, whereas reconstitution of PBMCs with miR−124 abolished the effects of HCV−Exo on MDSC induction. Taken together, these results indicate that HCV-associated exosomes can transfer immunomodulatory viral RNA from infected cells to neighboring immune cells and trigger MDSC expansion, which subsequently promotes TFR differentiation and inhibits TFH function. This study reveals a previously unrecognized path that represents a novel mechanism of immune dysregulation during chronic viral infection.