Littérature scientifique sur le sujet « Human lymphocytes, regulatory RNAs, immune system »

Abstract The pathogenesis of chronic lymphocytic leukemia (CLL) is stringently associated with a tumor-supportive microenvironment and a dysfunctional immune system. Of note, CLL cells themselves induce changes in surrounding cells, and extracellular vesicles (EVs) released by CLL cells represent a newly discovered mechanism of cell-cell communication. EVs are membrane enclosed nanoparticles 30 to 1000 nm in size and are able to reprogram recipient cells by transferring proteins and RNA molecules from their cell of origin. Thus, we aimed to analyze CLL cell-derived EVs present in blood plasma of CLL patients as well as those released by the CLL cell line MEC-1, in order to understand their role within the microenvironment. EVs were isolated from blood plasma of CLL patients and healthy donors, as well as from MEC-1 cell culture supernatant by serial centrifugation and density-based separation. Characterization of EVs by electron microscopy and immunoblot analysis revealed vesicles 20 to 300 nm in size, which are positive for various EV marker proteins such as Rab5a and Hsp70. Proteome analysis via mass spectrometry indicated differences in the composition of plasma derived EVs and peripheral blood mononuclear cells (PBMCs) from the respective patient, as well as between plasma derived EVs from healthy donors compared to CLL patients. Regarding the later, CLL EVs were specifically enriched for proteins involved in antigen presentation, endocytosis signaling as well as integrin mediated signaling and leukocyte extravasation. RNA analysis by BioAnalyzer profiling indicated an enrichment of small RNAs in EVs compared to cells. Subsequent small RNA sequencing revealed a unique microRNA signature of MEC-1 EVs with the 5 most abundant miRNAs encompassing about 60% of all detected miRNAs. Among them, the CLL-relevant miR-21 and miR-155, as well as miR-146a were selectively enriched in EVs. Moreover, Y RNAs, another class of small non-coding, regulatory RNAs, were highly enriched in MEC-1 EVs and their presence was also observed in plasma EVs of CLL patients. We uncovered a rapid uptake of CLL cell-derived EVs by human monocytes and macrophages. Whether the identified proteins and RNA transcripts shown to be enriched in CLL EVs induce phenotypic changes in targeted cells is being investigated. Further, quantification of plasma EVs in a large cohort of CLL patients is currently conducted and differences in the amount of EVs in correlation to disease outcome are analyzed. Harboring a distinct RNA and protein profile, EVs are potent vehicles for shuttling RNA and proteins to recipient cells and might be involved in the establishment of a supportive microenvironment in CLL. Functional analyses regarding possible effects of CLL EVs on target cells will broaden the knowledge of CLL pathogenesis and might help to identify new therapeutic options for CLL. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction: Molecular alterations involved in development of classical Hodgkin lymphoma (cHL) are only partially known. Genetic alterations in NFkB pathway and the imbalance of T regulatory (Treg) and TH17 lymphocytes has been recognized as critical pathogenetic mechanism involved in immune scape and blockade of apoptosis in Reed-Sternberg cells. Emerging evidences suggests that NFkB activation can promote lymphocyte proliferation and survival, and therapeutic inhibition of the NFkB pathway have been proposed. Recently, our group showed an increase of circulating Treg cells in patients with cHL at diagnosis, however, after therapy, elevated levels of circulating TH17 cells was observed. Increased frequencies of Treg lymphocytes in the tumor microenvironment and peripheral blood have been proposed as one of the mechanisms for this anergic state. TH17 exhibit effector functions in immune system and tumor-infiltrating TH17 cells are associated with better prognosis in human. Objectives: In this study we aimed to evaluate the immune gene expression profile in whole blood of cHL patients at diagnosis and after treatment, and evaluate pathways and gene interaction networks. Methods: This is an open multicenter study and, so far, we included 51 patients consecutively from February 2011 to November 2015. Twenty consecutively diagnosed cHL patients, with whole blood RNA extracted at diagnosis and after treatment, were recruited for this study and prospectively evaluated. All patients were HIV negative and received ABVD chemotherapy protocol and radiotherapy if necessary. The general expression of 96 messengers RNAs present in the peripheral blood and involved in immune response was performed by a customized quantitative real-time PCR array (TaqMan¨ Low Density Array). The data was normalized with B2M mRNAs levels and relative gene expression was calculated by the 2^DDCt method, considering Wilcoxon test and Benjamini-Hochberg adjustment to correct p-values. The differentially expressed genes were used to conduct functional/pathway enrichment analysis and construct gene interaction networks. Functional annotation networks were generated using Ingenuity Pathway Analysis (IPA; Ingenuity Systems) software. Results: From the 20 patients included for this study, 12 (60%) were male, 5 (31%) had Epstein Barr virus related cHL, 18 (90%) patients presented with B symptoms, 19 (95%) patients had advanced diseases at diagnosis (stage IIBX, III and IV) and 10% of patients relapsed. We considered paired samples from 15 patients before and after treatment. At diagnosis we observed that cHL patients presented higher expression of CD274 (2 fold, p=0.018), CD28 (1.5 fold, p=0.041), CTLA-4(1.5 fold, p=0.004), FAS (1.4 fold, p=0.041), ICOS (2.1 fold, p=0.015) and IL-10 (2.7 fold, p=0.002), and decreased expression of CCL2 (-2.7 fold, p=0.026), CCL5 (-1.6 fold, p=0.012), CD40 (-1.9 fold, p=0.003), CSF2 (-1.9 fold, p=0.012). We found no association between clinical and epidemiological characteristics with immune gene expression profile. We have found that after treatment, patients displayed a specific gene expression profile related to the top 5 canonical pathways summarized in following figure: We also built a biological network to investigate the connection between the differentially expressed genes and to predict the status (activation/inhibition) of the other connected genes (nodes). The in silico analysis revealed that NFkB, a node which its signaling activation is predicted to be activated before treatment and inhibited after (following figures). The network also showed different central node molecules (molecules connected with multiple other nodes from the network), that are indirectly related to Hodgkin lymphoma and should be further investigated as potential drugable targets. Conclusions: In this study, we showed that, at diagnosis, cHL patients presented an inflammatory gene expression profile in blood that changes after treatment to an effector/immunological one. NFkB is predicted to be activated before treatment and inhibited after ABVD chemotherapy and radiotherapy. This kind of system biology approach helped us to understand that cHL associated immunosuppression and the immune reconstitution after treatment maybe the key to develop new prognostic factors and treatment strategies as well as identify drugable targets. Figure 1 Figure 1. Figure 2 Figure 2. Figure 3 Figure 3. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 50 The Epstein-Barr virus (EBV) is one of the most major human pathogen that establish long-term latent, or chronic infections, which is associated with a heterogeneous group of lymphoma, including Burkitt's lymphoma, Hodgkin's lymphoma (HL), NK-T lymphomas and lymphoproliferative disease. These malignancies are subdivided into in terms of EBV latent infection pattern, with typical three types of latency: type I to type III. HL is characterized by a minority of neoplastic Hodgkin and Reed-Sternberg (HRS), which are embedded in non-neoplastic bystanders, mostly B and T cells, but also macrophages. Without these bystander cells, these HL cells are incapable of being engrafted in immunodeficient mice. In this context, the non-tumor immune cells are tumor-supportive “inflammatory niche”. Because of the complexity of interplay between tumor and tumor surrounding immune cells, the detailed mechanism and how tumor cells escape from the attack of host immune cells remains an open question. Small RNAs including miRNAs are well known intra-cellular regulatory elements of gene expression. Recently, it was reported that they are conjugated in exosomes and transferred to cells and are involved in tumor metastasis by educating tumor surrounding niche. Moreover, it was also reported that EBV-infected lymphocytes produce exosomes that contain viral encoded, EBV specific miRNAs (BART-miRNA) and that these could be transferred in host cells and decrease the levels of known cellular targets. Accordingly, we hypothesized that EBV+ tumor derived exosomal BART-miRNA might redirect tumor surrounding immune cells from tumor reactive into tumor- -supportive “inflammatory niche”, which ultimately leads to tumor progression. To this aim, first, we evaluated tumor derived viral encoded BART-miRNA in EBV+HL clinical specimens by using BART-miRNA specific probe in situ hybridization. As expected, these EBV specific BART-miRNA could be detected in HRS as well as in tumor surrounding inflammatory niche, especially macrophage. This result indicated that tumor derived EBV specific BART-miRNA could transfer to the non-tumor cells in the tumor inflammatory niche, supporting the in vivo relevance of secretary EBV specific miRNA. Next, we evaluated the properties of exosomes produced by EBV+ cells (EBV-Ex). To this aim, EBV-Ex was harvested either from the media of the type III or type I EBV-transformed lymphoid cell line. Then, by using transwell co-culture system, we tested the delivery and the effect of EBV-Ex on human peripheral blood mononuclear cells (PBMC) derived monocyte/macrophage (Mo/Mf). As a result, we detected uptake of fluorochrome dye-labeled EBV-Exo in Mo/Mf. We also confirmed exosomal BART miRNA transfer in Mo/Mf. Surprisingly, exosome from Type III latency (Type III-Ex) was relatively enriched in BART miRNA, and were potent on Mo/Mf in inducing surface CD69 expression (Fig.A). This is in contrast to that of exosome from Type I latency (Type I-Ex), in which BART miRNA were relatively vacant and were weak in inducing surface CD69 expression (Fig.A). Panels of cytokine analysis by Q-PCR revealed that type III-Ex treated Mo/Mf displayed an anti-inflammatory/immunosuppressive cytokine rich signature, especially IL-10, compared to type I-Ex treated Mo/Mf, suggesting the possibility that type III-Ex might polarize macrophage into immunosuppressive M2-like phenotype. Intriguingly, type III-Ex from BART miRNA deletion mutant derivative cell lines totally lack the type III -Ex signature. Moreover, ectopic expression of a part of BART in Type I cells changed the EBV-Ex signature from type III to type I (Fig.B), suggesting the importance of specific BART lesion in functional EBV-Ex production in terms of Mo/Mf polarization. Taken these together, secretary tumor derived miRNAs in EBV associated malignancy, specifically in EBV+HL, might play a certain role in tumor inflammation niche. EBV might utilize the exosomal machinery to secrete key viral-encoded miRNAs, through which a small number of neoplastic EBV+ cells could modulate the tumor microenvironment. Disclosures: No relevant conflicts of interest to declare.

Background: Autoimmune diseases result from the interplay of cellular effectors like T and B cells, regulatory cells in addition to molecular factors like cytokines and regulatory molecules. Methods: Different electronic databases were searched in a non-systematic way to find out the literature of interest. Results: Pathogenesis of autoimmune diseases involves typical factors such as genetic background including HLA and non HLA system genes, environmental factors such as infectious agents and inflammatory cells mainly T and B lymphocytes abnormally activated leading to immune dysfunction. Other recently reported less typical factors such as micro-RNAs, circular RNAs, myeloperoxidase, vimentine and microbiome dysbiosis seem to be potential target therapies. Conclusion: We aimed in this manuscript to review common factors in the pathogenesis of autoimmune diseases.

Long non-coding RNAs (lncRNAs) represent crucial transcriptional and post-transcriptional gene regulators during antimicrobial responses in the host innate immune system. Studies have shown that lncRNAs are expressed in a highly tissue- and cell-specific- manner and are involved in the differentiation and function of innate immune cells, as well as inflammatory and antiviral processes, through versatile molecular mechanisms. These lncRNAs function via the interactions with DNA, RNA, or protein in either cis or trans pattern, relying on their specific sequences or their transcriptions and processing. The dysregulation of lncRNA function is associated with various human non-infectious diseases, such as inflammatory bowel disease, cardiovascular diseases, and diabetes mellitus. Here, we provide an overview of the regulation and mechanisms of lncRNA function in the development and differentiation of innate immune cells, and during the activation or repression of innate immune responses. These elucidations might be beneficial for the development of therapeutic strategies targeting inflammatory and innate immune-mediated diseases.

Abstract Growing evidence indicates that arsenic can cause long-lasting and irreversible damage to the function of the human immune system. It is known that forkhead box protein 3(Foxp3), which is specifically expressed in regulatory T cells (Tregs), plays a decisive role in immunoregulation and is regulated by DNA methylation. While evidence suggests that epigenetic regulated Foxp3 is involved in the immune disorders caused by arsenic exposure, the specific mechanism remains unclear. In this study, after primary human lymphocytes were treated with different doses of NaAsO2, our results showed that arsenic induced the high expression of DNMT1 and Foxp3 gene promoter methylation level, thereby inhibiting the expression levels of Foxp3, followed by decreasing Tregs and reducing related anti-inflammatory cytokines, such as interleukin 10 (IL-10) and interleukin 10 (IL-35), and increasing the ratio of CD4+/CD8+ T cells in lymphocytes. Treatment with DNA methyltransferase inhibitor 5-Aza-CdR can notably inhibit the expression of DNMT1, effectively restoring the hypermethylation of the Foxp3 promoter region in primary human lymphocytes and upregulating the expression levels of Foxp3, balancing the ratio of CD4+/CD8+ T cells in lymphocytes. It also activates the secretion of anti-inflammatory cytokines and restores the immune regulatory functions of Tregs. In conclusion, our study provides limited evidence that DNMT1-mediated Foxp3 gene promoter hypermethylation is involved in immune dysfunction caused by arsenic in primary human lymphocytes. The study can provide a scientific basis for further understanding the arsenic-induced immune dysfunction in primary human lymphocytes.

Within the immune system, microRNAs (miRNAs) exert key regulatory functions. However, what are the mRNA targets regulated by miRNAs and how miRNAs are transcriptionally regulated themselves remain for the most part unknown. We found that in primary human memory T helper lymphocytes, miR-150 was the most abundantly expressed miRNA, and its expression decreased drastically upon activation, suggesting regulatory roles. Constitutive MIR150 gene expression required the RFX family of transcription factors, and its activation-induced down-regulation was linked to their reduced expression. By performing miRNA pull-down and sequencing experiments, we identified PDGFA-associated protein 1 (PDAP1) as one main target of miR-150 in human T lymphocytes. PDAP1 acted as an RNA-binding protein (RBP), and its CRISPR/Cas-9–mediated deletion revealed that it prominently contributed to the regulation of T-cell proliferation. Overall, using an integrated approach involving quantitative analysis, unbiased genomics, and genome editing, we identified RFX factors, miR-150, and the PDAP1 RBP as the components of a regulatory axis that restrains proliferation of primary human T lymphocytes.

Arsenic is known to cause damage to the body’s immune system by inducing epigenetic changes. However, the molecular mechanism of this damage remains elusive. Here, we report that arsenic disrupts the morphology of lymphocytes, decreases cell viability, and results in abnormal proportions of T lymphocyte subsets. Moreover, our results revealed that arsenic can reduce global acetylation of histone H4 at K16 (H4K16 ac) in lymphocytes via decreasing the level of males absent on the first but upregulates mRNA and protein levels of the forkhead/winged-helix box P3 ( Foxp3) gene by increasing the acetylation of histone H4 at K16 (H4K16) at the promoter of Foxp3. Finally, arsenic-induced dysfunction of regulatory T cells (Tregs) could be ameliorated by trichostatin A. Our research indicates that arsenic-induced immunosuppressive effect in human lymphocytes may be related to the acetylation of H4K16 at the promoter of Foxp3 and that histone deacetylase inhibitors may play a role in the prevention and treatment of immune injury caused by arsenic.

Abstract Introduction: In healthy pregnancy, maternal and fetal compartments are physically separated by multiple cell layers and the fetal immune system displays an ‘in-experienced’ phenotype in utero. The uterus as an immunologic barrier contributing to the naïve state of the fetal immune system has not been explored thus far. Methods: A prospective cohort study of fetuses born to mothers with prior uterine scar was undertaken (UCLA IRB # 11-002962). Cord blood lymphocytes were analyzed for memory status of the T regulatory cells (CD4+FoxP3+RO/RA) and blinded from placental location prior to final analysis. Results: In this prospective cohort study, we identified placental implantation in apposition to a uterine scar as a sufficient factor for fetal in utero immune activation (CD45RO+), specifically in the regulatory T cell compartment. Our results (N=20) identify a risk difference of 90% with a relative risk of 10 (p<0.05) of activation (RO+) of the FoxP3+ regulatory T cells when the placenta was implanted over the prior uterine scar. Discussion: Our study demonstrates that intrauterine formation of tolerogenic fetal responses is caused by fetal exposure to a scarred uterus. Our results highlight the role that uterine integrity plays as an immunologic barrier.

Gut mucosal surfaces separate the external environment from the internal sterile environment and so represent a first line of defence system. This barrier faces environments rich in pathogens that have developed effective mechanisms for colonisation of epithelial surfaces and invasion of mucosal tissues, but also harmless antigens such as food, airborne antigens or commensal bacterial flora. The latter represent the vast majority of the encountered antigens and require an appropriate response characterised by either ignorance or active suppression. However, for the former, a robust immune response is needed. Mucosae have developed a complex immune system that is capable of mounting an immune response against pathogenic antigens, while maintaining the required ignorance or active suppression against non-pathogenic antigens. Taking advantage of this knowledge, strategies have been devised to induce oral tolerance to antigens involved in experimental autoimmune disease or human conditions. It is now known that oral tolerance induces the up-regulation and activation of T cells with regulatory properties, a subtype of CD4+ T cells whose function is to regulate functions of other T lymphocytes to avoid excessive immune activation. Amongst them, the Th3 cells (cells that express the latency-associated peptide on the surface and secrete transforming growth factor β, a cytokine with immunoregulatory properties) are especially relevant in the induction of oral tolerance. Orally fed antigens seek to generate these types of cells in the treatment of autoimmune diseases in experimental animals or human subjects.

Recenti studi sull'intero genoma umano hanno dimostrato che i long noncoding RNA (lncRNAs) sono pervasivamente trascritti nel genoma e stanno emergendo come nuovi elementi chiave di diversi processi fisiopatologici, compresi lo sviluppo, il differenziamento delle cellule, il cancro, l'infiammazione e infezione virale cronica. Dato che i meccanismi che controllano la regolazione di linfociti umani da parte dei lncRNAs sono ancora poco conosciuti così come la loro espressione in queste cellule, abbiamo purificato 13 diverse sottopopolazioni di linfociti umani (da T-CD4 +, T-CD8 + e popolazioni di linfociti B) da sangue periferico per effettuare una completa analisi del trascrittoma di tali cellule mediante tecnologia RNA-seq utilizzando la piattaforma Illumina. Abbiamo collezionato più di due miliardi di RNA-Seq reads in un pannello di 63 campioni di linfociti umani per identificare specifici o nuovi lncRNAs per ogni sottogruppo, utilizzando sia approcci basati sul genoma di riferimento sia approcci di assemblaggio de novo. Per l'identificazione di nuovi lncRNAs specificamente espressi nelle nostre cellule, abbiamo adottato due approcci definiti “mapping-first” (Tophat e Star come mappatori e Cufflinks per l'identificazione di nuovi trascritti) e un metodo definito “assembly-first de novo” basato su Trinity. I nuovi trascritti sono stati poi processati per soddisfare una serie di requisiti che permettono di discriminare nuovi potenziali lncRNAs tra tutti gli mRNA identificati (sequenza di lunghezza> 200 basi, almeno due esoni, senza domini proteici noti in Pfam, basso potenziale codificante secondo i parametri di PhyloCSF e posizione intergenica nel genoma). Abbiamo scoperto che diversi lncRNAs sono preferenzialmente espressi in specifiche sottopopolazioni linfocitarie e che i loro pattern di espressione cambiano in modo molto specifico durante il differenziamento delle cellule T. Non solo abbiamo identificato signature di lncRNA subset-linfocitari specifiche, ma analisi di Gene Ontology (GO) hanno evidenziato un coinvolgimento dei geni protein coding prossimali a tali lncRNA signature in processi chiave dei linfociti come attivazione delle cellule T e la differenziamento.
Recent genome-wide studies have shown that long non-coding RNAs (lncRNAs) are pervasively transcribed in the genome and are emerging as new powerful players involved in several physio-pathological processes, including development, cell differentiation, cancer, inflammation and chronic viral infection. Since the mechanisms that control the regulation of human lymphocytes by lncRNAs are poorly understood as their expression in these cells, we purified 13 different human lymphocytes subsets (from T-CD4+, T-CD8+ and B lymphocyte populations) from peripheral blood to perform a comprehensive transcriptome analysis by RNA- seq using Illumina platform. We collected over than two billions RNA-seq reads across a panel of 63 purified lymphocyte samples to identify specific or new lncRNAs for each subset using both reference-based and de novo assembly approaches. For the identification of new lncRNAs specifically expressed in our cell we adopted two mapping-first approaches (TopHat and Star as mappers and Cufflinks for the identification of new transcripts) and an assembly-first de novo method based on Trinity. The new transcripts are then processed to satisfy a set of requirements that discriminate new potentially lincRNAs among all mRNAs identified (sequence length>200 bases, at least two exons, does not match any known protein domains from Pfam, must have a low predicted coding potential score by PhyloCSF and intergenic location in the genome). We found that different lincRNAs are preferentially expressed in specific lymphocyte subsets and that their expression patterns change in very specific manner during T cell differentiation. Not only we identified lymphocyte-subset-specific lincRNA signatures, but Gene Ontology (GO) enrichment analysis of the their neighbouring protein coding genes highlights an involvment in T cell activation and differentiation.

Orientadores: Patrícia Maria Bergamo Favaro, Sara Teresinha Olalla Saad
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: As síndromes mielodisplásicas (SMD) são um grupo heterogêneo de doenças caracterizadas por hematopoese ineficaz e risco de progressão para leucemia mieloide aguda (LMA). SMD de baixo de risco é caracterizada por um aumento de apoptose na medula óssea e alterações clínicas com perfil autoimune, enquanto que na SMD de alto risco há uma evasão imune, baixa apoptose e danos secundários ao DNA, contribuindo para a progressão para LMA. Essas evidências, junto com os dados de terapia imunossupressora em pacientes com SMD, sugerem o papel do sistema imune na progressão desta doença. Entretanto, o papel do sistema imune não é claro, e estudos que abordem o perfil das células T são importantes para o melhor entendimento da patogênese da SMD. Formin-like 1 (FMNL1) pertence à família de proteínas formina, indispensáveis para muitos processos fundamentais actina-dependentes. FMNL1 é restritamente expressa em células derivadas de linhagem hematopoética e superexpressa em células neoplásicas hematopoéticas malignas. Recentemente, foi descrito que FMNL1 está envolvida no processo de citotoxicidade de células CD8+. Desse modo, estudar a expressão de FMNL1 tanto nos linfócitos como nas células da MO dos pacientes com SMD, poderia contribuir para o melhor entendimento do papel dessa nova proteína neste modelo de neoplasia hematológica. No presente estudo, foi observada uma diminuição significativa na contagem absoluta de linfócitos periféricos no grupo SMD, após ajuste para idade, quando comparada com o grupo de doadores saudáveis (controle). Entretanto, houve um aumento da frequência de células CD3+, resultante do aumento significativo das subpopulações de células CD3+CD4+ no grupo de alto risco e CD3+CD8+ no grupo de baixo risco, de acordo com as classificações FAB e WHO. A razão CD4:CD8 encontrou-se aumentada no grupo de alto risco comparado com o de baixo risco. Dependência transfusional foi correlacionada positivamente com a porcentagem de CD3+CD4+, enquanto que a idade dos pacientes correlacionou-se de forma negativa com a porcentagem de CD3+ e CD3+CD8+. Os níveis de expressão de FOXP3, nas células CD3+ de sangue periférico, foram significativamente menores no grupo de baixo risco quando comparado com o grupo controle, e esse padrão se repetiu para a expressão de IL10. A quantificação dos transcritos de IL10 correlacionou-se negativamente com a porcentagem de células CD3+CD8+. Em conclusão, evidenciamos que pacientes com SMD apresentaram um menor número de linfócitos, porém com a frequências das células T CD3+, CD3+CD4+ e CD3+CD8+ aumentadas. Os pacientes de baixo risco apresentaram uma diminuição da expressão de FOXP3 e de IL10, quadro característico de um microambiente apoptótico e inflamatório. Já no grupo de alto risco, a expressão de FOXP3 e de IL10 aumenta em relação ao grupo de baixo risco. É interessante ressaltar que nos pacientes com SMD houve uma correlação entre o aumento da expressão de IL10 e a diminuição das células T CD3+CD8+, sugerindo a contribuição das Tregs na progressão da doença através da produção de IL10. A análise da expressão de FMNL1 em células CD3+ de sangue periférico não denotou diferenças significativas entre os pacientes com SMD e o grupo controle. Entretanto observou-se uma correlação positiva entre a expressão de FMNL1 e o número de células CD3+CD4+ e ambos com a dependência transfusional. Quanto à expressão de FMNL1 em amostras de MO, houve uma expressão significativamente menor nos pacientes com SMD quando comparado com as células de doadores normais, além de uma correlação negativa entre FMNL1 e número de citopenias. Usando modelos de linhagens celulares hematopoéticas para a diferenciação, observou-se um aumento significativo na expressão gênica e protéica de FMNL1 durante a diferenciação megacariocítica. Esses resultados sugerem a participação de FMNL1 na ativação de linfócitos CD4+ no sangue periférico e na diferenciação hematopoética na medula óssea
Abstract: Myelodysplastic syndromes (MDS) are a heterogeneous group of disorders characterized by ineffective hematopoiesis and risk of progression towards acute myeloid leukemia. Low-risk MDS is characterized by increased apoptosis in the bone marrow (BM), with a clinical autoimmune profile, whereas in high-risk MDS an immune evasion, low apoptosis and secondary DNA damage occurs, contributing to the progression of AML. This evidence, together with the data of immunosuppressive therapy in patients with MDS, suggests a role of the immune system in the progression of this disease. However, this role of the immune system is remains unclear, and studies that address the profile of T cells are important for a better understanding of the pathogenesis of MDS. Formin-like 1 (FMNL1) belongs to the family of proteins formina indispensable for many fundamental processes in actin-dependent. FMNL1 is strictly expressed in hematopoietic lineage derived cells, and overexpressed in malignant hematopoietic neoplastic cells. FMNL1 has recently been reported to be involved in the cytotoxicity of CD8+ cells. Thus, studies on the expression of FMNL1, both in lymphocytes and BM cells of MDS patients, could contribute to a better understanding of the role of this protein in this new model of hematologic malignancy. In the present study, we observed a significant decrease in absolute peripheral lymphocyte counts in the MDS group, after adjusting for age, compared with the healthy donor group (control). However, there was an increased frequency of CD3+, resulting in a significant increase of the CD3+CD4+ subpopulation in high risk and CD3+CD8+ in MDS low risk, according to FAB and WHO classifications. CD4:CD8 ratio was increased in the high risk when compared to the low risk group. Transfusion dependence was positively correlated with the percentage of CD3+CD4+, whereas the age of patients correlated negatively with the percentage of CD3+ and CD3+CD8+. The expression levels of FOXP3, in peripheral blood CD3+ cells, was significantly lower in the low risk group compared to controls and this pattern was repeated for the expression of IL10. Interestingly, IL10 transcripts correlated negatively with the percentage of CD3+CD8+. In conclusion, we found that patients with MDS had a lower lymphocyte number, however presented an increased frequency of CD3+ and CD3+CD8+ T cells. Our low risk patients showed a decreased expression of FOXP3 and IL10, characteristic of apoptotic and inflammatory microenvironment. In the high risk group, the expression of FOXP3 and IL10 was normal. Interestingly, there was a correlation between increasing expression of IL10 and reduction of CD3+CD8+ T cells in patients, suggesting the contribution of Treg in disease progression due to IL10 production. Analysis of FMNL1expression in CD3+ cells of peripheral blood showed no significant differences between patients with MDS and the control group. However, there was a positive correlation between FMNL1 expression and the number of CD3+CD4+, and both were transfusion dependence. FMNL1 expression in BM samples was significantly lower in MDS patients when compared with cells from normal donors, and there was a negative correlation between FMNL1 and number of cytopenias. Using models of hematopoietic cell lineages for differentiation, we observed an increase in gene and protein expression of FMNL1 during megakaryocytic and granulocytic differentiation. These results suggest the participation of FMNL1 in the activation of CD4+ lymphocytes in peripheral blood and bone marrow hematopoietic differentiation
Mestrado
Fisiopatologia Médica
Mestre em Ciências

It has been shown that the state of the human immune system and its activity determines the development, course and prognosis of many oncological diseases. To date, various immunotherapeutic approaches have been developed, of which the most promising is adoptive cell therapy (ACT). An increase in the effectiveness of this type of therapy could be achieved by using synthetic small interfering RNAs (siRNAs) to suppress the expression of key immune checkpoint (ICI) genes (PD1, CTL4) in T-lymphocytes, which are involved in cellular immunosuppression. However, there is a problem of selecting an effective method for delivering such siRNAs to T-lymphocytes. In the present study, we developed a synthetic siRNA specific to the mRNA sequence of the PD1 gene and evaluated the efficiency of its delivery to activated human T-lymphocytes using chemically modified siRNA, histone H1, – 18 – Global science. Development and novelty and the liposomal agent HiperFect. Ex vivo activated T-lymphocytes from healthy donors were used. The efficiency of siRNA transfection into cells and its confirmation was assessed using flow cytofluorometry and confocal microscopy. As a result of the study, a high (51%) efficiency of transfection into these cells using chemically modified "self-delivering" siRNA was shown. For other methods of delivery of miRNA to T-lymphocytes, low efficiency is shown. Thus, our data suggest that of the three approaches used in this work for miRNAs delivery to activated T-lymphocytes, the most effective is the use of “self-delivering” chemically modified cholesterol miRNA.