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Project description:Insm1, encoding a zinc finger protein, is expressed specifically in neuroendocrine cells. Recent study showed the first evidence of Insm1 expression in medullary thymic epithelial cells (mTEC). Here we investigated the expression and function of Insm1 in mTEC. Mutation of Insm1 resulted in decreased proportion of mTEChi although normal development of other types of thymic cells. We detected altered expression of a subset of tissue-restricted antigens (TRAs) and mild decreased expression of Aire and Fezf2 in Insm1 mutant mTEC. We further showed that Insm1 recognizes a DNA sequence which is similar to the CCCTC-Binding factor (CTCF) binding motif. Mutation of Insm1 altered CTCF binding genome widely and thus the expression of genes. In nude mice transplanted with Insm1 mutant thymus, autoimmune responses were observed in multiple peripheral tissues. In thymus specific Insm1 mutant mice, we detected decreased induction of regulatory T (Treg) cells in the thymus, obvious lymphocytes infiltration and autoimmune antibody reaction in several peripheral tissues. In thymic epithelial cells specific Insm1 overexpression mice, we detected enlarged mTEC proportion and increased expression of mTEC specific genes. Thus, we suggest that Insm1 is a novel regulator of mTEC function and autoimmunity.
2024-01-01 | GSE193927 | GEO
Project description:Insm1, encoding a zinc finger protein, is expressed specifically in neuroendocrine cells. Recent study showed the first evidence of Insm1 expression in medullary thymic epithelial cells (mTEC). Here we investigated the expression and function of Insm1 in mTEC. Mutation of Insm1 resulted in decreased proportion of mTEChi although normal development of other types of thymic cells. We detected altered expression of a subset of tissue-restricted antigens (TRAs) and mild decreased expression of Aire and Fezf2 in Insm1 mutant mTEC. We further showed that Insm1 recognizes a DNA sequence which is similar to the CCCTC-Binding factor (CTCF) binding motif. Mutation of Insm1 altered CTCF binding genome widely and thus the expression of genes. In nude mice transplanted with Insm1 mutant thymus, autoimmune responses were observed in multiple peripheral tissues. In thymus specific Insm1 mutant mice, we detected decreased induction of regulatory T (Treg) cells in the thymus, obvious lymphocytes infiltration and autoimmune antibody reaction in several peripheral tissues. In thymic epithelial cells specific Insm1 overexpression mice, we detected enlarged mTEC proportion and increased expression of mTEC specific genes. Thus, we suggest that Insm1 is a novel regulator of mTEC function and autoimmunity.
2024-01-01 | GSE193926 | GEO
Project description:Exosomes are nano-sized vesicles released by cells into the extracellular space and have been shown to be present in thymic tissue both in mice and in humans. The source of thymic exosomes is however still an enigma and hence it is not known whether thymic epithelial cells (TECs) are able to produce exosomes. In this work, we have cultured human TECs and isolated exosomes. These exosomes carry tissue-restricted antigens (TRAs), for example, myelin basic protein and desmoglein 3. The presence of TRAs indicates a possible role for thymic epithelium-derived exosomes in the selection process of thymocytes. The key contribution of these exosomes could be to disseminate self-antigens from the thymic epithelia, thus making them more accessible to the pool of maturing thymocytes. This would increase the coverage of TRAs within the thymus, and facilitate the process of positive and negative selection.
| S-EPMC4575951 | biostudies-literature
Project description:To examine the Endocrine thymic epithelial cell transcriptome within the mTEC-III compartment we sorted this population from young Insm1 cKO mice and performed bulk RNAseq
2023-08-28 | GSE236073 | GEO
Project description:Positive and negative selection of thymocytes in the thymus are critical for the development of a mature and self-tolerant T-cell repertoire. The proapoptotic Bcl-2 family member Bim is important for negative selection by inducing apoptosis in thymocytes receiving a strong signal through their antigen receptor. However, in the case of ubiquitous self-antigens (UbA), Bim is not required for the clonal deletion of self-reactive thymocytes, suggesting the existence of nonapoptotic clonal deletion mechanisms. Unlike UbA, clonal deletion to tissue-restricted antigens (TRAs) requires positive selection and CCR7-mediated migration to the medulla. This led us to hypothesize that Bim is required for the latter. To study the role of Bim in clonal deletion to TRA, we constructed bone marrow (BM) chimeras using OT-I Bim-deficient or -sufficient donor bone marrow and recipients that express membrane bound chicken ovalbumin under control of the rat insulin promoter (Rip-mOVA). We found that clonal deletion to TRA was completely abrogated in the absence of Bim and large numbers of mature OT-I CD8 T cells survived in the periphery. Despite the large numbers of autoreactive T cells, the chimeras did not develop diabetes and OT-I Bim-deficient T cells from these chimeras were functionally impaired. Collectively, these data provide unique evidence of a differential, thymocyte-intrinsic, molecular requirement downstream of the T-cell receptor (TCR) for clonal deletion to UbA versus TRA and highlight the profound ability of other tolerance mechanisms to control T-cell autoreactivity in the absence of thymic clonal deletion.
| S-EPMC3271910 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2023-08-27 | GSE236075 | GEO
Project description:Central tolerance prevents autoimmunity, but also limits T cell responses to potentially immunodominant tumor epitopes with limited expression in healthy tissues. In peripheral APCs, γ-IFN-inducible lysosomal thiol reductase (GILT) is critical for MHC class II-restricted presentation of disulfide bond-containing proteins, including the self-antigen and melanoma Ag tyrosinase-related protein 1 (TRP1). The role of GILT in thymic Ag processing and generation of central tolerance has not been investigated. We found that GILT enhanced the negative selection of TRP1-specific thymocytes in mice. GILT expression was enriched in thymic APCs capable of mediating deletion, namely medullary thymic epithelial cells (mTECs) and dendritic cells, whereas TRP1 expression was restricted solely to mTECs. GILT facilitated MHC class II-restricted presentation of endogenous TRP1 by pooled thymic APCs. Using bone marrow chimeras, GILT expression in thymic epithelial cells (TECs), but not hematopoietic cells, was sufficient for complete deletion of TRP1-specific thymocytes. An increased frequency of TRP1-specific regulatory T (Treg) cells was present in chimeras with increased deletion of TRP1-specific thymocytes. Only chimeras that lacked GILT in both TECs and hematopoietic cells had a high conventional T/Treg cell ratio and were protected from melanoma challenge. Thus, GILT expression in thymic APCs, and mTECs in particular, preferentially facilitates MHC class II-restricted presentation, negative selection, and increased Treg cells, resulting in a diminished antitumor response to a tissue-restricted, melanoma-associated self-antigen.
| S-EPMC7336541 | biostudies-literature
Project description:Immune responses against lung-associated self-antigens (self-Ags) are hypothesized to play a role in the development of chronic lung graft rejection. We determined whether immune responses to lung self-Ags, K-alpha-1-tubulin (K?1T) and Collagen V (Col-V) in the absence of alloimmunity, could promote airway inflammation and fibrosis. Following syngeneic murine orthotopic lung transplantation (LTx) we administered antibodies (Abs) to either K?1T or Col-V or in combination to both of these self-Ags. As compared to recipients of isotype control Abs, K?1T Abs and/or Col-V Abs-treated recipients had marked lung graft cellular infiltration and bronchiolar fibrosis. This inflammation was also associated the accumulation of K?1T and Col-V-specific interferon-?+ and IL-17+ T cells. Notably, the administration of Abs to K?1T led to cellular and humoral immune responses to Col-V prior to development of fibrosis, and vice versa, indicating that epitope spreading can occur rapidly in an alloantigen independent manner. Collectively, these data support a model of chronic LTx rejection where the progressive loss of self-tolerance through epitope spreading promotes airway fibrosis. Strategies that target autoreactive Abs may be useful to inhibit chronic rejection of lung grafts.
| S-EPMC4169463 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2021-03-16 | GSE164118 | GEO
Project description:Deletion of self-antigen-specific T cells during thymic development provides protection from autoimmunity. However, it is unclear how efficiently this occurs for tissue-restricted self antigens, or how immune tolerance is maintained for self-antigen-specific T cells that routinely escape deletion. Here we show that endogenous CD4+ T cells with specificity for a set of tissue-restricted self antigens were not deleted at all. For pancreatic self antigen, this resulted in an absence of steady-state tolerance, while for the lung and intestine, tolerance was maintained by the enhanced presence of thymically-derived antigen-specific Foxp3+ regulatory T (Treg) cells. Unlike deletional tolerance, Treg cell-mediated tolerance was broken by successive antigen challenges. These findings reveal that for some tissue-restricted self antigens, tolerance relies entirely on nondeletional mechanisms that are less durable than T cell deletion. This might explain why autoimmunity is often tissue-specific, and it offers a rationale for cancer vaccine strategies targeting tissue-restricted tumor antigens.
| S-EPMC4654997 | biostudies-literature