MAIT cells altered phenotype and cytotoxicity in lupus patients are linked to renal disease severity and outcome

IntroductionSystemic lupus erythematosus (SLE) is an autoimmune disease in which circulating immune complexes can cause different types of glomerulonephritis, according to immune deposits and to the type of glomerular cell injury. Proliferative lesions represent the most severe form of lupus nephritis (LN) and often lead to kidney failure and death. Mucosal-associated invariant T (MAIT) cells are a subset of innate-like T cells that recognize microbial-derived ligands from the riboflavin synthesis pathway. Although abundant in peripheral blood, MAIT cells are enriched in mucosal and inflamed tissues. While previous studies have reported concordant results concerning lower MAIT cell frequencies in the blood of SLE patients, no information is known about MAIT cell function and LN severity and outcome.MethodsIn the current study, we analyzed the baseline phenotype and function of peripheral blood MAIT cells by flow cytometry in 26 patients with LN and in a control group of 16 healthy individuals.ResultsWe observe that MAIT cell frequencies are markedly reduced in blood of LN patients. MAIT cells from patients have an altered phenotype in terms of migration, proliferation and differentiation markers, notably in most severe forms of LN. Frequencies of PMA/ionomycin stimulated MAIT cells secreting effector molecules, such as proinflammatory IL-17 and cytotoxic protein granzyme B, are higher in LN patients. Patients undergoing a complete renal remission after immunosuppressive therapy had higher MAIT cell frequency, lower expression of proliferation marker Ki-67 and granzyme B (GzB) at inclusion. Remarkably, GzB production defines a predictive model for complete remission.DiscussionWe report here that blood MAIT cells display proinflammatory and cytotoxic function in severe lupus nephritis which may play a pathogenesis role, but without association with systemic lupus activity. Finally, low cytotoxic profile of MAIT cells may represent a promising prognostic factor of lupus nephritis remission one year after induction therapy

Modeling CD4+ T-cell antitumor immune response 1) in a model of transplantable tumors with inducible antigen expression and 2) in a model of "spontaneous tumors"

Le rôle des lymphocytes T CD4+ dans la progression des tumeurs et dans l'immunité anti-tumorale est de plus en plus reconnu chez l'homme et chez la souris. Les mécanismes effecteurs de l’immunité T CD4+ contre le cancer ont été étudiés principalement dans des systèmes de tumeurs transplantées. Dans ces modèles, de nombreuses cellules tumorales meurent au moment de l'implantation, ce qui conduit à la libération de l'antigène tumoral (Ag) dans un contexte inflammatoire. Ceci contraste avec la croissance lente et non-destructrice des tumeurs humaines aux stades précoces. Nous avons montré que la présentation de l’Ag retreint par le CMH-II DBY, libéré par des cellules tumorales mortes injectées en sous-cutané, peut persister durant plusieurs semaines dans le ganglion drainant. L’activation précoce d’une réponse immune dirigée contre l’Ag lors de l’injection de lignées tumorales peut gêner l’étude des relations entre les tumeurs et le système immunitaire. Par conséquent, nous avons généré une lignée tumorale dans laquelle l’expression de DBY peut être induite in vivo à distance de l’implantation. Nous avons également utilisé un modèle de tumeurs pulmonaires endogènes se développant dans des souris transgéniques KrasG12D, p53flox et exprimant DBY de manière spécifique. Notre objectif était d'étudier dans ces deux modèles l'histoire naturelle de la réponse des lymphocytes T CD4+ spécifiques de la tumeur. Dans le système de tumeur transplantée «Ag inductible », nous avons montré que DBY est présenté de manière efficace à des cellules naïves T CD4+ spécifiques dans les ganglions drainant la tumeur. Les réponses prolifératives et effectrices sont similaires dans les systèmes où DBY est exprimé de façon inductible in vivo ou constitutive. Le récepteur de co-stimulation ICOS, ainsi que les récepteurs co-inhibiteurs PD-1 et BTLA sont régulés positivement sur les lymphocytes T CD4+ spécifiques en réponse à l’Ag. La production de cytokines en réponse à une restimulation in vitro révèle un profil effecteur mixte TH1 /TH17. Notamment, un petit pourcentage de lymphocytes T co-expriment les marqueurs de cytotoxicité LAMP-1 et granzyme B. Ainsi, lorsqu’un Ag apparaît à distance de l'implantation de la tumeur, il n’est pas ignoré et n’induit pas de tolérance immune. D'autres mécanismes doivent être considérés pour expliquer l'absence de rejet de tumeur efficace malgré l’activation et la migration des cellules effectrices T CD4+ dans les tumeurs. Les travaux réalisés sur le modèle de tumeurs pulmonaires endogènes sont en cours. A ce stade, nous avons observé que, comme dans les tumeurs transplantées, l’Ag est présenté aux LT CD4+ naïfs qui prolifèrent dans le ganglion drainant et ne se différencient pas en cellules T régulatrices, même aux stades très avancés de la maladie. La capacité des tumeurs à induire une réponse T effectrice semble liée à leur stade de développement. Durant la phase tumorale précoce, les LT spécifiques de DBY produisent de l’IFN-γ et du granzyme B. En revanche, des LT spécifiques produisant de l'IL-17 sont retrouvés dans les poumons de souris ayant des tumeurs invasives de stade terminal. Bien que l'IL-17 puisse favoriser la progression des tumeurs, y compris dans les modèles induits par l’oncogène KrasG12D, de nouvelles données suggèrent que les cellules effectrices TH17 possèdent un haut degré de plasticité et peuvent présenter une activité anti-tumorale. Notre modèle pourrait être utile pour tester de nouvelles stratégies de ciblage de l’IL-17 dans l'immunothérapie du cancer.The role of CD4+ T cells in both tumor progression and immunity is being increasingly acknowledged in humans and mice. CD4+ T cell immunity against cancer has been mostly studied using murine transplanted tumor systems. In these models, many tumor cells die at the time of surgical implantation, leading to the release of tumor antigen (Ag) in an inflammatory context. This contrasts with the slow and non-destructive growth of early stage human tumors. Here, we show that the presentation of a MHC class II-restricted model (male, DBY) Ag released by dying fibroblastic tumor cells may last more than 3 weeks in the tumor draining lymph node (dLN). This artificial, early and long lasting priming precludes the study of the interactions between the immune system and tumors at the steady state. We therefore generated a cell line that could be induced to efficiently express DBY as a neoAg after implantation. We also took advantage of a previously described mouse model of genetically engineered, KrasG12D p53flox lung adenocarcinoma to generate a “spontaneous” tumor model expressing DBY. Our aim was to study in these two models the natural history of the tumor-specific CD4+ T cell response. In the transplanted tumor system, we show that the Ag reaches the dLNs and is efficiently presented to naïve specific CD4+ T cells. The proliferative and effector responses were similar in the inducible and constitutively expressed Ag tumor systems. The ICOS co-stimulatory receptor, and the PD-1 and BTLA co-inhibitory receptors were upregulated on the Ag specific CD4+ T cells in the dLN. We did not observe de novo induction of tumor-specific regulatory T cells. Finally, the pattern of secreted lymphokines in the dLN, spleen and tumor after in vitro Ag restimulation was similar, with a mixed TH1/TH17 response. Notably, a small percentage of DBY-specific effector T cells also displayed a cytolytic phenotype marked by the co-expression of granzyme B and LAMP-1. Thus, when the neo-Ag appears at distance of tumor implantation, the tumor was not ignored and did not induce tolerance of naïve CD4+ T cells. Other mechanisms have to be thought to explain the absence of tumor rejection despite efficient priming and migration of effector CD4+ T cells into tumors. Similarly to the strong proliferative response mentioned above, the DBY tumor Ag was efficiently presented in LNs draining “spontaneous” lung tumors, and induced activation and proliferation of adoptively transferred naive T cells. After priming they did not convert into Tregs, even in end-stage disease. This work is still ongoing, but preliminary results show that activated DBY-specific T cells from the dLN and the lungs produced IFN-γ and granzyme B during early stages of the disease. In contrast, IL-17 secreting cells were found exclusively in the lungs from mice with late-stages invasive tumors. Although IL-17 may enhance tumor progression, including in models driven by the Kras oncogen, emerging data strongly suggest that TH17 effector cells demonstrate a high grade of plasticity and can display anti tumor activity. Little is known about the antigen specificity of IL-17 production in lung cancer patients, and our model could be useful to test new strategies targeting either positively or negatively tumor Ag-specific TH17 cells in cancer immunotherapy

Modèles tumoraux murins destinés à l'étude de la réponse immune antitumorale (mise au point de nouveaux modèles de tumeurs spontanées et transplantées)

PARIS-BIUP (751062107) / SudocSudocFranceF

Protective role of mouse IgG1 in cryoglobulinaemia; insights from an animal model and relevance to human pathology

International audienc

Induction of anergic or regulatory tumor-specific CD4+ T cells in the tumor-draining lymph node

International audienceCD4+ T cell antitumor responses have mostly been studied in transplanted tumors expressing secreted model antigens (Ags), while most mutated proteins in human cancers are not secreted. The fate of Ag-specific CD4+ T cells recognizing a cytoplasmic Ag in mice bearing autochthonous tumors is still unclear. Here we show, using a genetically engineered lung adenocarcinoma mouse model, that naive tumor-specific CD4+ T cells are activated and proliferate in the tumor-draining lymph node (TdLN) but do not differentiate into effectors or accumulate in tumors. Instead, these CD4+ T cells are driven toward anergy or peripherally-induced Treg (pTreg) differentiation, from the early stage of tumor development. This bias toward immune suppression is restricted to the TdLN, and is maintained by Tregs enriched in the tumor Ag-specific cell population. Thus, tumors may enforce a dominant inhibition of the anti-tumor CD4 response in the TdLN by recapitulating peripheral self-tolerance mechanisms

Presentation_1_MAIT cells altered phenotype and cytotoxicity in lupus patients are linked to renal disease severity and outcome.pdf

IntroductionSystemic lupus erythematosus (SLE) is an autoimmune disease in which circulating immune complexes can cause different types of glomerulonephritis, according to immune deposits and to the type of glomerular cell injury. Proliferative lesions represent the most severe form of lupus nephritis (LN) and often lead to kidney failure and death. Mucosal-associated invariant T (MAIT) cells are a subset of innate-like T cells that recognize microbial-derived ligands from the riboflavin synthesis pathway. Although abundant in peripheral blood, MAIT cells are enriched in mucosal and inflamed tissues. While previous studies have reported concordant results concerning lower MAIT cell frequencies in the blood of SLE patients, no information is known about MAIT cell function and LN severity and outcome.MethodsIn the current study, we analyzed the baseline phenotype and function of peripheral blood MAIT cells by flow cytometry in 26 patients with LN and in a control group of 16 healthy individuals.ResultsWe observe that MAIT cell frequencies are markedly reduced in blood of LN patients. MAIT cells from patients have an altered phenotype in terms of migration, proliferation and differentiation markers, notably in most severe forms of LN. Frequencies of PMA/ionomycin stimulated MAIT cells secreting effector molecules, such as proinflammatory IL-17 and cytotoxic protein granzyme B, are higher in LN patients. Patients undergoing a complete renal remission after immunosuppressive therapy had higher MAIT cell frequency, lower expression of proliferation marker Ki-67 and granzyme B (GzB) at inclusion. Remarkably, GzB production defines a predictive model for complete remission.DiscussionWe report here that blood MAIT cells display proinflammatory and cytotoxic function in severe lupus nephritis which may play a pathogenesis role, but without association with systemic lupus activity. Finally, low cytotoxic profile of MAIT cells may represent a promising prognostic factor of lupus nephritis remission one year after induction therapy.</p

Aspergillus -induced pneumonia in adult without obvious immunodeficiency: test the burst!

International audienc

Outcome of SARS-CoV-2 infection linked to MAIT cell activation and cytotoxicity: evidence for an IL-18 dependent mechanism

International audienceImmune system dysfunction is paramount in Coronavirus disease 2019 (COVID-19) severity and fatality rate. Mucosal-Associated Invariant T (MAIT) cells are innate-like T cells involved in mucosal immunity and protection against viral infections. Here, we studied the immune cell landscape, with emphasis on MAIT cells, in a cohort of 182 patients including patients at various stages of disease activity. A profound decrease of MAIT cell counts in blood of critically ill patients was observed. These cells showed a strongly activated and cytotoxic phenotype that positively correlated with circulating pro-inflammatory cytokines, notably IL-18. MAIT cell alterations markedly correlated with disease severity and patient mortality. SARS-CoV-2-infected macrophages activated MAIT cells in a cytokine-dependent manner involving an IFNα-dependent early phase and an IL-18-induced later phase. Therefore, altered MAIT cell phenotypes represent valuable biomarkers of disease severity and their therapeutic manipulation might prevent the inflammatory phase involved in COVID-19 aggravation