Letteratura scientifica selezionata sul tema "LT γδ"

Abstract Intestinal γδ intraepithelial lymphocytes (γδ IEL) serve as the first line of defense against pathogen invasion. We recently identified a transmissible hyperproliferative γδ IEL (γδ HYP) phenotype that protects against enteric infection, and these mice have no signs of overt intestinal pathology. Given that IELs are metabolically constrained to prevent aberrant activation, we hypothesized that the bioenergetics of γδ HYPIELs may regulate their effector function. Electron microscopy revealed a 70% increase in mitochondrial number (p=0.005) and 24% increase in mitochondrial area (p=0.04) in γδ HYPIELs relative to WT. Seahorse mitochondrial stress assays on γδ IELs showed a 50% increase in spare respiratory capacity in γδ HYPIELs compared to WT (p=0.014). Mitochondrial metabolism was shown to influence γδ T cell cytokine production, and similarly, we found that stimulation with PMA and ionomycin reduced the frequency of IFNγ +γδ IELs by 59% in γδ HYPrelative to WT (p<0.0001). We also observed that γδ HYPIELs exhibit higher CD39 expression compared to WT (p<0.0001), and a CD39 hisubset produces less IFNγ compared to CD39 negand CD39 intcells (p<0.0001) The addition of the ATP-synthase inhibitor oligomycin during IEL stimulation increased IFNγ production by both WT and γδ HYPIELs by 66% and 44%, respectively (p<0.0001). Together, our data demonstrate that the shift towards high CD39 expression and elevated mitochondrial metabolism contribute to decreased IFNγ production in γδ HYPIELs. Further understanding of the mechanisms regulating γδ IEL homeostasis and effector function may ultimately allow fine tuning of mucosal surveillance to confer protection against intestinal injury or infection while limiting aberrant cytotoxicity. Supported by NJCCR (COCR23PRF024)

Abstract Intraepithelial lymphocytes (IEL) expressing the γδ T cell receptor (TCR) provide a rapid response to limit enteric pathogen invasion. Despite constant γδTCR triggering in vivo, these IELs remain immunologically quiescent until their activation threshold is surpassed. Activated γδ IELs limit viral replication by producing type I interferons (IFN), such as IFNα, yet the extent to which IFNα activates γδ IELs remains unknown. To this end, murine small intestinal γδ IELs were stimulated ex vivowith 1 ug/mL αCD3, 10 ng/mL IFNα or both for 5 h. We observed a 26%±10 increase in IFNγ +γδ IELs treated with αCD3 and IFNα compared to αCD3 treatment alone (p<0.0001) and a 2-fold increase in IFNγ MFI (p<0.0001). Using Nur77-GFP mice, we found that only Nur77 +γδ IELs produced IFNγ (p<0.0001), indicating that TCR signaling is necessary for IFNα-induced effector function. Suboptimal αCD3 stimulation (0.1 ug/mL) was sufficient to increase the frequency of IFNγ +γδ IELs following IFNα exposure relative to αCD3 alone (p<0.001). To interrogate the molecular mechanism involved in IFNα co-stimulation, γδ IELs were treated with PMA and/or ionomycin in the presence or absence of IFNα. Ionomycin and IFNα increased the frequency of IFNγ +γδ IELs by 16%±7 compared to ionomycin alone (p<0.0001), whereas PMA had no effect. Pharmacological inhibition of NFAT signaling (10 uM INCA6) abrogated both TCR- or IFNα-induced γδ IEL IFNγ production (p<0.01 or p<0.0001, respectively). Lastly, we observed that the co-stimulatory effect of IFNα was lost in STAT4-deficient γδ IELs compared to WT (p<0.0001). Together, these data indicate that low level TCR signaling through NFAT is required for IFNα to rapidly enhance γδ IEL IFNγ production in a STAT4-dependent manner. This work was supported by the National Institutes of Health R01 DK119349, the New Jersey Commission on Cancer Research, Busch Biomedical Research grant and the RBHS Chancellor Scholar Award (KLE).

Abstract Abstract 1901 Regulatory γδ T cells (γδ Tregs) is a novel subset of cells with immunosuppressive function while methods for γδ Treg induction is rarely introduced and its role in graft-versus-host disease (GVHD) prevention remains unkown. Decitabine, a kind of hypomethylating agents, can act synergistically with TGF-β1 to convert a variety of αβ T cells to regulatory αβ T cells with suppressive function but its role in induction and function of γδ Tregs has not been reported. We show here the role of decitabine for the induction of γδ Tregs. Moreover, we provide functional analysis and underlying mechanisms of decitabine-induced γδ Tregs relative to γδ Tregs without decitabine induction as well as in vivo evidences of their preventions on GVHD. Human peripheral blood mononuclear cells (PBMCs) were cultured with IL-2, IL-15, TGF-β1 and zoledronic acid (ZOL). On day 2, 0.5μmol/ml decitabine was added to aliquots of PBMCs. On days 4, 7, and 10, half of the supernatant volume was replaced with media containing cytokines. On day 11, frequencies of γδ Tregs were detected by flow cytometry (FACS). We found the frequency of γδ Tregs was 36.2% in TGF-β1/IL-15/ZOL stimulated group (referred to as common γδ Tregs below) and 59.9% in IL-2/TGF-β1/IL-15/ZOL/decitabine stimulated group (referred to as decitabine-induced γδ Tregs) (p<0.05). In order to compare immunosuppressive function of the two populations, γδ T cells containing γδ Tregs were isolated by magnetic cell sorting system (MACS) and tested for their ability to suppress proliferation of alloreactive PBMCs using CFSE-based assay. After 5 days of in vitro culture, CFSE-labeled PBMCs proliferation was significantly reduced in the presence of enriched γδ Tregs even at 8:1(PBMCs: γδ Tregs) ratio. The inhibition rate was significantly different (decitabine-induced γδ Tregs VS common γδ Tregs at ratio 1:1 is 81.3% VS 68.2%, p<0.05). To clarify the underlying mechanisms we performed ELISA to measure levels of inhibitory cytokines IL-10, IL-4 and TGF-β1 in supernatant of CFSE-based assay. We noted an elevated IL-10 secretion in the decitabine-induced γδ Tregs group compared with common γδ Tregs group (92.7±11pg/ml VS 10.3±2pg/ml at ratio 1:1, p<0.01). We confirmed the result by intracellular IL-10 detection using FACS. Previous reports showed high levels of inducible T-cell costimulator (ICOS) were correlated with IL-10 synthesis. So γδ Tregs were monitored for ICOS expression by FACS. The result revealed that ICOS expression was up-regulated in decitabine-induced γδ Tregs in contrast to common γδ Tregs (MFI: 268 VS 54). Stability of Foxp3 is a critical factor in the immunosuppressive ability of Tregs. Thus we evaluated the frequency of γδ Tregs after 5 days in CFSE-based assay. We observed loss of Foxp3 expression in decitabine-induced γδ Tregs was negligible (<3%) while 15.5% common γδ Tregs lost foxp3 expression. To confirm the results in vitro we tested the functional ability to prevent GVHD in vivo. GVHD was induced in NOD/SCID mice following busulfan and anti-CD122 condition and 1×107 PBMCs transfusion. Animals were co-injected with either decitabine-induced γδ Tregs or common γδ Tregs at a ratio of 1:1. Survival time and GVHD manifestations of the transplanted mice were evaluated. As a result, transplantation of human PBMCs alone induced lethal GVHD with average survival time 25± 8 days while the survival time was 43± 5 days and 58±7 days in mice co-injected with common γδ Tregs and decitabine-induced γδ Tregs, respectively (p<0.05). Clinical manifestations such as hunched back, diarrhea, and body weight loss were statistically different among 3 groups. To investigate the infiltration of human lymphocytes into nonlymphoid tissues in GVHD mice, we performed immunohistochemical analysis of the liver and intestines using anti-human CD45. Remarkably abundant invasion of human CD45+ cells was observed around the veins in the liver and intestines transplanted with PBMCs alone while less invasion in mice co-injected with common γδ Tregs and the lest invasion in mice co-injected with decitabine-induced γδ Tregs. Altogether, our findings reveal that decitabine and the cytokines can efficiently syngenerize to induce γδ Tregs with enhanced immunosuppression on GVHD which are via higher levels of IL-10 production due to ICOS up-regulation as well as stability of Foxp3 expression. Thus γδ Tregs may be potentially exploited therapeutically in a variety of transplantation settings. Disclosures: No relevant conflicts of interest to declare.

Abstract γδ intraepithelial lymphocytes (IEL) migrate along the basement membrane and into the lateral intracellular space (LIS) between adjacent intestinal epithelial cells (IEC) and is critical to limit microbial translocation across the barrier. Although activated γδ IELs produce interferon (IFN)-α, whether IFNα directly influences γδ IEL migratory behavior remains unknown. To test this, intravital microscopy was performed on GFP γδ T cell reporter mice treated with PBS or IFNα (1 μg, i.v., 3h). We found that γδ IEL track speed was increased 30% and migration into the LIS was enhanced by 75% in IFNα-treated mice compared to controls. To identify candidate genes involved in regulating γδ IEL motility, we performed RNAseq on γδ IELs isolated from control and IFNα-treated mice. As expected, IFNα induced IFN-stimulated gene expression including CD47 (3.5-fold increase), a transmembrane protein involved in neutrophil transepithelial migration. Stimulation of ex vivo cultured γδ IELs with IFNα resulted in a 3-fold increase in CD47 expression compared to unstimulated controls. Next, to investigate whether IFNα enhances γδ IEL motility in vitro, GFP γδ IELs were co-cultured with enteroids expressing membrane tdTomato and treated with 10ng/ml IFNα for 3h. IFNα increased γδ IEL speed (4.5±0.2 vs 3.4±0.2 μm/min; p&lt;0.05) and displacement (47±3.0 μm vs 34±3.1, p&lt;0.05) relative to untreated controls. Addition of anti-CD47 blocking antibody (MIAP301) abrogated the IFNα-mediated increase in γδ IEL migratory behavior. Taken together, these data demonstrate that IFNα enhances γδ IEL motility via a CD47-mediated mechanism, and suggests that CD47 may represent a conserved mechanism of leukocyte migration within the epithelial barrier.

Background The prognosis of pediatric T-cell acute lymphoblastic leukemia (T-ALL) has improved with minimal residual disease (MRD)-stratified therapy, however, gamma delta T cell receptor positive (γδ) T-ALL remains a high-risk (HR) group. Limited studies have explored the clinical and genomic characteristics of γδ T-ALL, prompting us to conduct a comprehensive analysis of this entity and to identify determinants of outcome. Methods Through a consortium of 13 groups, we assembled a cohort of 200 patients up to 25 years of age with γδ T-ALL enrolled in clinical trials between 2000 and 2018. Clinical data of patients with non-γδ T-ALL enrolled on the same clinical trials were collected (n = 1,067). Complete remission (CR) was defined when bone marrow (BM) showed M1 cytomorphology and/or MRD &lt;1% without evidence of extramedullary disease at end of induction/consolidation (EOI/EOC) and failure to achieve CR was considered treatment failure. A total of 76 γδ T-ALL samples were analyzed by whole genome (WGS) and/or transcriptome (RNAseq) sequencing. Results The frequency of γδ T-ALL was 8.0% of T-ALL cases. Patients with γδ T-ALL exhibited a higher rate of poor prednisone response ( P&lt;0.01), MRD &gt;1% at day 15 ( P&lt;0.01), at EOI ( P&lt;0.01) and EOC ( P&lt;0.01), compared to non-γδ T-ALL cases. Furthermore, patients with γδ T-ALL showed significantly worse 5-year event free survival (EFS, 65% v. 78%, P&lt;0.01) and overall survival (OS, 77% vs 83%, P=0.048). Almost all relapses of γδ T-ALL were isolated BM, while the central nervous system was the main site of relapse in non-γδ T-ALL, suggesting slow treatment response and chemo-resistance to the current treatment in γδ T-ALL. However, γδ T-ALL showed a higher rate of toxic death during treatment (7.6% vs 4.0%, P&lt;0.01), suggesting the need for different therapeutic strategies and risk-classification, rather than treatment intensification. Strikingly, patients less than 3 years of age with γδ T-ALL exhibited significantly poor EFS (33% v. 70% [3-10 years] and 73% [&gt;10], P&lt;0.01) and OS (49% v. 78% [3-10] and 82% [&gt;10], P&lt; 0.01) ( Fig. A), a difference not observed in non-γδ T-ALL. MRD &gt;1% at EOI showed poor EFS (51% v. 96% [MRD&lt;0.01%] and 91% [1%&gt;MRD&gt;0.01%], P&lt;0.01) and OS (66%). Integrated analysis of WGS and RNAseq identified enrichment of several genomic subtypes in γδ T-ALL, including STAG2/LMO2, hyperdiploidy with recurrent gains of chromosomes 8, 10, 11, 13q and 19, a recently identified “LMO2 γδ-like” subtype with distinct gene expression and LMO2/MYC/MYCN alterations, TLX3-rearranged (-R), and PICALM::MLLT10. No TAL1 nor TLX1-R were detected. STAG2/LMO2 was associated with age at diagnosis before 3 years, and extremely poor outcome, with 4 out of 5 cases dying within three years of diagnosis ( Fig. B). Of 24 STAG2/LMO2 T-ALL (additional 5 non-γδ, 13 TCR unknown cases), 22 of which were diagnosed by age three. All STAG2/LMO2 cases had alterations resulting in LMO2 activation and STAG2 inactivation, most commonly a single rearrangement between these two genes, and upregulation of HBE1, the LIN28-let7 pathway and stem cell proliferation pathways, suggesting a fetal hematopoietic origin. STAG2 has a critical role in the maintenance of enhancer-promoter looping mediated by the cohesin complex. To examine the consequences of STAG2 alterations, we performed integrated genomic/epigenomic analysis of the STAG2/LMO2 (MOLT-14 and PER-117) and STAG2 knockout (KO)/addback T-ALL lines. Chromatin loop sizes defined by H3K27ac HiChIP was highest in STAG2/LMO2 lines compared to other T-ALL. Following restoration of STAG2 expression in MOLT-14, CD34 and ID1/2 were down-regulated and H3K27ac was enriched in pathways related to T-cell differentiation. STAG2 KO in the non- STAG2/LMO2, LMO2-activated line PF382 identified genes also upregulated in STAG2/LMO2 primary samples, including CDK4 and STAG1. STAG2 KO lines exhibited partial compensation of STAG2 binding sites by STAG1 and upregulation of γδ-related genes, RORC and ID1/3. High throughput screening of 2,050 small molecules identified efficacy of HDAC, CDK and PARP inhibitors in STAG2/LMO2 lines. Conclusion Very young onset γδ T-ALL, but not non-γδ T-ALL, is enriched for the STAG2/LMO2 subtype and is a very high risk form of T-ALL. STAG2 loss perturbs chromatin organization and hematopoietic differentiation. Moreover, we demonstrate efficacy of novel therapeutic approaches that are needed to cure this form of leukemia.

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy in adults with dismal outcomes. γδ T cells have been reported to exert effective anti-tumor activities on various types of solid tumors and hematologic malignancies, and thus become a potential weapon used in the treatment of cancer. However, compared to the striking results demonstrated in vitro and in mouse models, the clinical efficacy of γδ T cells-based immunotherapy is disappointing. Meanwhile, recent studies identified a pro-tumor role of γδ T cells in some types of solid tumors. Whether γδ T cells could be transformed from warriors to foe in the environment of leukemia is unclear. In the current study, we aim to dissect the abnormal changes and functions of intrinsic γδ T cells in the context of AML. Considering bone marrows (BM) are the primary tumor foci of AML and likely provide more representative immune characteristics during leukemia development, the immunophenotyping analyses of γδ T cells in BM from newly diagnosed AML patients (n = 21) were detected using flow cytometry, compared with healthy individual controls (n = 21). We observed that the proportion of γδ T cells and the composition of Vδ1+ and Vδ2+ subgroups were comparable between AML patients and healthy controls. Interestingly, a dramatically elevated subpopulation in γδ T cells expressing CD25 and dim CD127 was observed in AML patients compared with that in healthy controls (3.2% versus 0.8%, P &lt; 0.001). Since their phenotypes are akin to the conventional CD4+ regulatory T cells (Tregs), these CD25+CD127dim γδ T cells are called γδ Tregs here. Paired comparison was also performed on AML patients at diagnosis (n = 13) and completed remission (CR) after chemotherapy (n = 13). A significant decrease in proportion of γδ Tregs was observed at CR, compared with that at newly diagnoses (3.1% versus 0.4% (P &lt; 0.001). These results suggest that this aberrant γδ T subset, γδ Tregs, is induced in the microenvironment of AML and can be reversed after effective therapy for elimination of leukemia blasts. To further explore the direct effect of AML blasts on γδ T cells, primary malignant cells were sorted from AML patients, and co-cultured with peripheral blood mononuclear cells (PBMCs) isolated from healthy donors. As expected, γδ Tregs was significantly induced and the frequency was continuously elevated from 0.2% to 4.0% following the increased ratios of AML cells (P &lt; 0.001). These results confirmed that AML cells were capable to trigger the transformation of normal γδ T cells into CD25+CD127dim γδ Tregs. To determine the function of this special γδ T subset, CD25+CD127dim γδ Tregs were expanded in vitro and co-cultured with AML cell lines, U937 cells. Unlike pamidronate-expanded cytotoxic Vδ2+ T cells, γδ Tregs lost the ability of killing AML cells. Furthermore, we explored the impact of γδ Tregs on the anti-AML activity of normal αβ T cells. γδ T cell-depleted PBMCs (more than 90% are αβ T cells) of healthy donors were co-cultured with U937 cells, with or without autologous γδ Tregs. Flow cytometry analysis showed that 7-AAD-positive fraction in U937 cells was dramatically increased from 0.3% to 7.6% after co-culture with PBMCs and without γδ Tregs. Whereas the mortality of U937 cells was gradually declined (from 7.6% to 4%) in the presence of γδ Tregs at increasing ratios (P = 0.031). During this process, γδ Tregs remarkably downregulated the expressions of HLA-DR and CD38, and productions of TNF-α and IFN-γ in both CD4+ and CD8+ αβ T cells. These findings indicated that γδ Tregs significantly impaired the cytotoxic ability of effector αβ T cells on AML cells, suggesting γδ Tregs play a suppressive role in the anti-leukemia immunity. In summary, we first reported the significant induction of CD25+CD127dim γδ Tregs in the primary BM of AML patients. These γδ Tregs did not exert anti-leukemia activity and attenuated the cytotoxic effect of normal αβ T cells. Our findings will help advance the current understanding of immune mechanism associated with leukemia cell evasion. It also proposes that boosting the cytotoxic γδ T cells should be coupled with inhibition of the suppressive γδ Tregs, for future improvement of γδ T-cell-based immunotherapy. Disclosures No relevant conflicts of interest to declare.

Abstract Objective To evaluate the antitumoral role of γδ TDC cells and αβ TDC cells in an experimental model of breast cancer. Methods Thirty female Balb/c mice were divided into 2 groups: control group (n = 15) and induced-4T1 group (n = 15), in which the mice received 2 × 105 4T1 mammary tumor cell line. Following the 28-day experimental period, immune cells were collected from the spleen and analyzed by flow cytometry for comparison of αβ TDC (TCRαβ+ CD11c+MHCII+) and γδ TDC (TCRγδ+CD11c+MHCII+) cells regarding surface markers (CD4+ and C8+) and cytokines (IFN-γ, TNF-α, IL-12 and IL-17). Results A total of 26.53% of γδ TDC - control group (p < 0.0001) - the proportion of αβ TDC was lower in splenic cells than γδ TDC; however, these 2 cell types were reduced in tumor conditions (p < 0.0001), and the proportion of IFN-γ, TNF-α, IL-12 and IL-17 cytokines produced by γδ TDC was higher than those produced by αβ TDC, but it decreased under conditions of tumor-related immune system response (p < 0.0001). Conclusion Healthy mice engrafted with malignant cells 4T1 breast tumor presented TDC with γδ TCR repertoire. These cells express cytotoxic molecules of lymphocytes T, producing anti-tumor proinflammatory cytokines.

Abstract γδ T cells localize to target tissues of graft-versus-host disease (GVHD) and therefore we investigated the role of host γδ T cells in the pathogenesis of acute GVHD in several well-characterized allogeneic bone marrow transplantation (BMT) models. Depletion of host γδ T cells in wild-type (wt) B6 recipients by administration of anti-T-cell receptor (TCR) γδ monoclonal antibody reduced GVHD, and γδ T-cell-deficient (γδ-/-) BM transplant recipients experienced markedly improved survival compared with normal controls (63% vs 10%, P &lt; .001). γδ T cells were responsible for this difference because reconstitution of γδ-/- recipients with γδ T cells restored GVHD mortality. γδ-/- recipients showed decreased serum levels of tumor necrosis factor α (TNF-α), less GVHD histopathologic damage, and reduced donor T-cell expansion. Mechanistic analysis of this phenomenon demonstrated that dendritic cells (DCs) from γδ-/- recipients exhibited less allostimulatory capacity compared to wt DCs after irradiation. Normal DCs derived from BM caused greater allogeneic T-cell proliferation when cocultured with γδ T cells than DCs cocultured with medium alone. This enhancement did not depend on interferon γ (IFN-γ), TNF-α, or CD40 ligand but did depend on cell-to-cell contact. These data demonstrated that the host γδ T cells exacerbate GVHD by enhancing the allostimulatory capacity of host antigen-presenting cells. (Blood. 2005;106:749-755)

The prognostic impact of the different tumor-infiltrating lymphocyte (TIL) subpopulations in solid cancers is still debated. Here, we investigated the clinicopathological correlates and prognostic impact of TILs, particularly of γδ T cells, in 162 patients with triple-negative breast cancer (TNBC). A high γδ T cell density (>6.625 γδ T cells/mm2) was associated with younger age (p = 0.008), higher tumor histological grade (p = 0.002), adjuvant chemotherapy (p = 0.010), BRCA1 promoter methylation (p = 0.010), TIL density (p < 0.001), and PD-L1 (p < 0.001) and PD-1 expression (p = 0.040). In multivariate analyses, γδ T cell infiltration (cutoff = 6.625 γδ T cells/mm2) was an independent prognostic factor (5-year relapse-free survival: 63.3% vs. 89.8%, p = 0.027; 5-year overall survival: 73.8% vs. 89.9%, p = 0.031, for low vs. high infiltration). This prognostic impact varied according to the tumor PIK3CA mutational status. High γδ T cell infiltration was associated with better survival in patients with PIK3CA wild-type tumors, but the difference was not significant in the subgroup with PIK3CA-mutated tumors. Altogether, these data suggest that high γδ T cell infiltrate is correlated with immune infiltration and might represent a candidate prognostic tool in patients with TNBC.

Gamma-delta (γδ) T cells are unconventional T cells that help control cytomegalovirus (CMV) infection in adults. γδ T cells develop early in gestation, and a fetal public γδ T cell receptor (TCR) clonotype is detected in congenital CMV infections. However, age-dependent γδ T cell responses to primary CMV infection are not well-understood. Flow cytometry and TCR sequencing was used to comprehensively characterize γδ T cell responses to CMV infection in a cohort of 32 infants followed prospectively from birth. Peripheral blood γδ T cell frequencies increased during infancy, and were higher among CMV-infected infants relative to uninfected. Clustering analyses revealed associations between CMV infection and activation marker expression on adaptive-like Vδ1 and Vδ3, but not innate-like Vγ9Vδ2 γδ T cell subsets. Frequencies of NKG2C+CD57+ γδ T cells were temporally associated with the quantity of CMV shed in saliva by infants with primary infection. The public γδ TCR clonotype was only detected in CMV-infected infants <120 days old and at lower frequencies than previously described in fetal infections. Our findings support the notion that CMV infection drives age-dependent expansions of specific γδ T cell populations, and provide insight for novel strategies to prevent CMV transmission and disease.

Les LT γδ contribuent à l'immunité anti-tumorale au sein du microenvironnement tumoral dans divers cancers. Malgré leurs fonctions effectrices bien décrites, de récentes études ont corrélé leur présence dans le microenvironnement tumoral à une meilleure progression des tumeurs solides, suggérant que les LT γδ peuvent présenter des activités pro-tumorales. Mon projet visait à caractériser ces LT γδ présentant des activités tumorales et à déchiffrer leur rôle dans le cancer. Nous avons démontré in vitro que les signaux inflammatoires favorisent le développement d'une sous-population de LT γδ régulateurs caractérisée par l'expression de CD73 et affichant des fonctions immunosuppressives par la production de molécules immunosuppressives telles que l'IL-10, l'adénosine et le facteur angiogénique et chimiotactique IL-8. Le défi associé à la caractérisation des LT γδ CD73+ réside dans l'évaluation de leur existence in vivo ainsi que de leur pertinence dans les cancers humains. Nous avons montré dans le cancer du sein que ~20% des lymphocytes γδ infiltrant la tumeur (γδ TILs) expriment CD73 et présentent les mêmes fonctions immunosuppressives que celles décrites in vitro, suggérant qu'ils pourraient favoriser le développement tumoral via ces mécanismes. En accord avec ces observations, nous avons montré que la présence de γδ TILs est associée à des grades tumoraux tardifs dans le cancer du sein. Nous avons étendu ces observations au cancer ovarien et montré que la densité des CD73+ γδ TILs est négativement corrélée à la survie des patients, suggérant que la densité des γδ TILs CD73+ pourrait être utilisée comme facteur pronostic en clinique. En utilisant l'imagerie par cytométrie de masse, nous avons étudié les réseaux cellulaires des γδ TILs régulateurs (CD73+) et de leurs homologues effecteurs (CD73-) dans les tumeurs d’ovaire afin de mieux comprendre leur rôle dans le cancer. Nos données montrent des écosystèmes immédiats différents pour les γδ TILs CD73+ par rapport aux CD73 renforçant l'idée que les LT γδ CD73+ et CD73- sont fonctionnellement différents.Dans l'ensemble, ces données améliorent nos connaissances sur l'immunobiologie des LT γδ dans le développement du cancer chez l’Homme, avec notamment la caractérisation approfondie du ce nouvel sous-ensemble de LT γδ régulateurs, leur localisation et leurs fonctions au sein du microenvironnement tumoral
Γδ T cells contribute to the anti-tumor immunity within the tumor microenvironment in various cancers. Despite their well-described effector functions, recent studies correlated their presence in the tumor microenvironment with solid tumor progression suggesting that γδ T cells may display pro-tumor activities. My project aimed to characterize those regulatory γδ T cells and decipher their role in cancer.We demonstrated in vitro that inflammatory signals promote the development of a regulatory γδ T cell sub-population characterized by the expression of CD73 and displaying immunosuppressive functions through the production of immunosuppressive molecules such as IL-10, adenosine and the angiogenic and chemotactic factor IL-8. The challenge associated with the characterization of CD73+ γδ T cells resides in assessing their existence in vivo as well as their relevance in human cancers. We showed in human breast cancer that ~20% of tumor infiltrating γδ T lymphocytes (TILs) expressed CD73 and displayed the same immunosuppressive functions as described in vitro, suggesting that they could promote tumor development via these mechanisms. In line with these observations, we showed that the presence of γδ TILs is associated with late tumor grades in breast cancer. We extended such observations to ovarian cancer and showed that the density of CD73+ γδ TILs negatively correlates with patient survival, suggesting that CD73+ γδ TILs density could be used as a prognosis factor. Using Imaging by Mass Cytometry, we investigated the cellular networks of regulatory γδ TILs (CD73+) and their effector counterpart (CD73-) in breast and ovarian tumors to better understand their role in cancer. Our data show different ecosystems for CD73+ compared to CD73- γδ TILs reinforcing the idea that CD73+ and CD73- γδ T cells are functionally different.Altogether, these data improve our knowledge on human γδ T cell biology during cancer development, with the in-depth characterization of the new regulatory γδ T cell subset, their localization and their functions within the tumor microenvironment