Project description:Mutations in the gene encoding the transcription factor AutoImmune REgulator (AIRE) are responsible for the ‘Autoimmune PolyEndocrinopathy Candidiasis Ecodermal Dystrophy’ syndrome. AIRE directs expression of tissue restricted antigens in the thymic medulla and in lymph node stromal cells and thereby substantially contributes to induction of immunological tolerance to self-antigens. Data from experimental mouse models showed that AIRE-deficiency leads to impaired deletion of autospecific T cell precursors. However, a potential role for AIRE in the function of regulatory T cell populations, which are known to play a central role in prevention of immunopathology, has remained elusive. Regulatory T cells of CD8+CD28low phenotype efficiently control immune responses in experimental autoimmune and colitis models in mice. We here show that CD8+CD28low Treg from AIRE-deficient mice are transcriptionally and phenotypically normal, exert efficient suppression of in vitro immune responses, but completely fail to prevent experimental colitis in vivo. Our data therefore demonstrate that AIRE plays an important role in the in vivo function of a naturally occurring regulatory T cell population. Total RNA was extracted from CD8+CD28low regulatory T lymphocytes isolated from wildtype and Aire-deficient C57BL/6 mice for comparison of gene expression profiles.
Project description:Mutations in the gene encoding the transcription factor AutoImmune REgulator (AIRE) are responsible for the ‘Autoimmune PolyEndocrinopathy Candidiasis Ecodermal Dystrophy’ syndrome. AIRE directs expression of tissue restricted antigens in the thymic medulla and in lymph node stromal cells and thereby substantially contributes to induction of immunological tolerance to self-antigens. Data from experimental mouse models showed that AIRE-deficiency leads to impaired deletion of autospecific T cell precursors. However, a potential role for AIRE in the function of regulatory T cell populations, which are known to play a central role in prevention of immunopathology, has remained elusive. Regulatory T cells of CD8+CD28low phenotype efficiently control immune responses in experimental autoimmune and colitis models in mice. We here show that CD8+CD28low Treg from AIRE-deficient mice are transcriptionally and phenotypically normal, exert efficient suppression of in vitro immune responses, but completely fail to prevent experimental colitis in vivo. Our data therefore demonstrate that AIRE plays an important role in the in vivo function of a naturally occurring regulatory T cell population.
Project description:To investigate the role of Aire in thymic selection, we examined the cellular requirements for generation of ovalbumin (OVA)-specific CD4 and CD8 T cells in mice expressing OVA under the control of the rat insulin promoter (RIP). Aire-deficiency reduced the number of mature single positive (SP) OVA-specific CD4+ or CD8+ T cells in the thymus, independent of OVA expression. Importantly, it also contributed in two way to OVA-dependent negative selection depending on the T cell type. Aire-dependent negative selection of OVA-specific CD8 T cells correlated with Aire-regulated expression of OVA. By contrast, for OVA-specific CD4 T cells, Aire affected tolerance induction by a mechanism that operated independent of the level of OVA expression, controlling access of antigen presenting cells to mTEC-expressed OVA. This study supports the view that one mechanism by which Aire controls thymic negative selection is by regulating the indirect presentation of mTEC-derived antigens by thymic dendritic cells. It also indicates that mTEC can mediate tolerance by direct presentation of Aireregulated antigens to both CD4 and CD8 T cells. Total RNA was extracted from medullary thymic epithelial cells isolated from wildtype and Aire-deficient C57BL/6 mice for comparison of gene expression profiles.
Project description:We show here that the T helper-fate is not fixed and that mature antigen-stimulated CD4 T cells can switch off Thpok expression and reactivate CD8- lineage genes. This unexpected plasticity results in the post-thymic termination of the T helper- program and the functional differentiation of distinct MHC class II restricted CD4 cytotoxic T lymphocytes Small intestine CD4 intraepithelial T lymphocytes from ThPOK-GFP reposter mice were isolated and sorted (FACS Aria) based on ThPOK and CD8aa expression. Cell were isolated either from non-experimental ThPOK-GFP reporter mice (WT) or after transfering CD4 naive T cells from ThPOK-GFP reporter mice to RAG-/-recipient animals (TR) as an experimental colitis model. Experimet was done in duplicate.
Project description:Colorectal cancer (CRC) is one of the most common cancers in France (36,000 new cases / year) and nearly 16,000 people die each year from this disease. The lymph node involvement of the surgical specimen is today the main tool on which is based the adjuvant treatment decision after curative surgical resection. The study of new predictive factors to identify patients at risk for developing a local or metastatic recurrence is therefore a major challenge.
It is now clear that the immune system plays a role in the control of tumor’s development, and it was shown that there was a correlation between the presence of a CD3+ T-lymphocyte infiltrate in colorectal cancers and patient survival. Preliminary studies suggest an important role of regulatory T-lymphocyte in the modulation of the antitumor immune response. The aim of our study is to follow a cohort of patients operated for colon cancer with curative intent to highlight the prognostic characteristics of the tumoral infiltrate by various lymphocyte populations (particularly T-lymphocytes but also B-lymphocytes and regulatory lymphocytes). It will be performed a preoperative analysis of blood circulating lymphocytes with antibodies specific for different cell populations (CD3, CD4, CD8, CD56, CD16, CD19, CD2) and stage of activation (CD25, CD69, HLA-DR ) or differentiation (CD24, CD38, CD27, CD103, CD62L, CCR7, CD45RA / RO, IgD). The presence of regulatory T-lymphocytes will also be analyzed. It will be performed on tumor sample a Tissue Microarrays for immunohistochemical study to determine the presence of different lymphocyte populations. We systematically study the markers CD68 (monocytes / macrophages), CD56 (NK cells), CD20 and CD79a (B cells / plasma cells), CD3 (T cells), CD8 (cytotoxic T), CD4 (helper T) FoxP3 (regulatory T), cytotoxicity of CD8 markers (Fas ligand, perforin and granzyme) and MHC I (antigen presentation) to explore the innate and adaptive immune responses. For each section, the different zones will be analyzed (center and invasive margin and healthy tissue). The main objective of the study is the influence of the tumor infiltration rate by CD3 + T cells on disease free survival at 2-years in patients with non-metastatic colon cancer resection. The secondary objective is to search a correlation between the rate of T-lymphocytes on preoperative blood sample and on tumor sample.
Project description:Thymic central tolerance is essential to preventing autoimmunity. In medullary thymic epithelial cells (mTECs), the Autoimmune regulator (Aire) gene plays an essential role in this process by driving the expression of a diverse set of tissue-specific antigens (TSAs), which are presented and help tolerize self-reactive thymocytes. Interestingly, Aire has a highly tissue-restricted pattern of expression, with only mTECs and peripheral extrathymic Aire-expressing cells (eTACs) known to express detectable levels in adults. Despite this high level of tissue specificity, the cis-regulatory elements that control Aire expression have remained obscure. We used sequence conservation analysis and ChIP-seq against the enhancer-associated histone mark H3K27ac to identify a candidate Aire cis-regulatory element. There is enrichment of H3K27ac near this element, ACNS1, in mTECs and the element also has characteristics of being NF-κB-responsive. Finally, we find that this element is essential for Aire expression in vivo and necessary to prevent spontaneous autoimmunity, reflecting the importance of this regulatory DNA element in promoting immune tolerance. Two experimental groups (GFP neg mTECs and GFP pos mTECs), each with three samples, and one control sample (D10 Th2 cells).
Project description:To investigate the role of Aire in thymic selection, we examined the cellular requirements for generation of ovalbumin (OVA)-specific CD4 and CD8 T cells in mice expressing OVA under the control of the rat insulin promoter (RIP). Aire-deficiency reduced the number of mature single positive (SP) OVA-specific CD4+ or CD8+ T cells in the thymus, independent of OVA expression. Importantly, it also contributed in two way to OVA-dependent negative selection depending on the T cell type. Aire-dependent negative selection of OVA-specific CD8 T cells correlated with Aire-regulated expression of OVA. By contrast, for OVA-specific CD4 T cells, Aire affected tolerance induction by a mechanism that operated independent of the level of OVA expression, controlling access of antigen presenting cells to mTEC-expressed OVA. This study supports the view that one mechanism by which Aire controls thymic negative selection is by regulating the indirect presentation of mTEC-derived antigens by thymic dendritic cells. It also indicates that mTEC can mediate tolerance by direct presentation of Aireregulated antigens to both CD4 and CD8 T cells.
Project description:Through a diversity of functional lineages, cells of the innate and adaptive immune system either drive or constrain immune reactions within tumors. Thus, while the immune system has a powerful ability to recognize and kill cancer cells, this function is often suppressed preventing clearance of disease. The transcription factor (TF) BACH2 controls the differentiation and function of multiple innate and adaptive immune lineages, but its role in regulating tumor immunity is not known. Here, we demonstrate that BACH2 is required to establish immunosuppression within tumors. We found that growth of subcutaneously implanted tumors was markedly impaired in Bach2-deficient mice and coincided with intratumoral activation of both innate and adaptive immunity but was dependent upon adaptive immunity. Analysis of tumor-infiltrating lymphocytes in Bach2-deficient mice revealed high frequencies of CD4+ and CD8+ effector cells expressing the inflammatory cytokine IFN-γ. Lymphocyte activation coincided with reduction in the frequency of intratumoral CD4+ Foxp3+ regulatory T (Treg) cells. Mechanistically, Treg-dependent inhibition of CD8+ T cells was required for BACH2-mediated tumor immunosuppression. These findings demonstrate that BACH2 is a key component of the molecular programme of tumor immunosuppression and identify a new target for development of therapies aimed at reversing immunosuppression in cancer. Analysis of tumor-infiltrating lymphocytes in Bach2-deficient mice revealed high frequencies of CD4+ and CD8+ effector cells expressing the inflammatory cytokine IFN-γ. Lymphocyte activation coincided with reduction in the frequency of intratumoral CD4+ Foxp3+ regulatory T (Treg) cells. Mechanistically, Treg-dependent inhibition of CD8+ T cells was required for BACH2-mediated tumor immunosuppression.
Project description:We explored the role of the autoimmune regulator (Aire) gene in supporting fetal tolerance during pregnancy with transgenic diphtheria toxin receptor (Aire-DTR) mice, in which Aire-expressing populations can be deleted by injection of diptheria toxins (DT). Aire-expressing cell depletion was found to cause intruterine growth restriction (IUGR) in both allogenic and syngeneic pregnancies. This phenotype is immune-mediated, as IUGR is rescued in Rag1-deficient mice, and involves a memory response, as demonstrated by severe IUGR in second pregnancies. We further explored this phenotype through single-cell RNA sequencing of leukocytes obtained from the secondary lymphoid organs (uterine and non-uterine-draining lymph nodes) of wild-type (WT) and Aire-DTR pregnant dams during allogeneic pregnancy. Transciptomic data reveals a shift in population distributions from naïve to effector CD4+ and CD8+ T cells in Aire-DTR mice. Within the effector CD4+ compartment, there was a significant shift away from Tregs and toward mature T effectors, most notably T follicular helper (Tfh) and Th17 cells. These findings support the idea that Aire is essential in maintaining immune homeostasis.