Project description:Thymic epithelial cells (TEC) control T cell development and play essential roles in establishing self-tolerance. Transcription factors controlling TEC development are poorly characterized. We report that Klf6 plays a critical role in TEC development. Mice deficient for Klf6 in TEC had a hypoplastic thymus - evident from fetal stages into adulthood. Proliferation of TEC was not reduced, but a dramatic increase in the frequency of apoptotic TEC in fetal and adult thymus was observed. Among cortical TEC (cTEC), we found expansion of a previously unreported cTEC population expressing the transcription factor Sox10. Medullary TEC (mTEC) subsets were not equally impacted with Ccl21a+ mTEC I and Tuft-like mTEC IV being disproportionately affected. Consistent with these TEC defects, naïve conventional T cells and NKT cells were reduced in the spleen, and signs of autoimmunity were evident. Thus, Klf6 has a pro- survival role in TEC and is also required for differentiation of the mTEC I and mTEC IV populations of TEC in adult mice. In this work, we report that mice with Foxn1-Cre mediated ablation of Klf6 in TEC demonstrate thymic hypoplasia beginning from prenatal life and extending through adulthood. Guided by single-cell transcriptional profiling, we determined that loss of Klf6 increased programmed cell death of TEC in prenatal and adult mice. In adult mice, thymic Klf6 deficiency severely impacted the mTEC I and mTEC IV populations. In addition, Klf6 deficiency led to the expansion of a previously uncharacterized cTEC population expressing Sox10 that is present in wild-type mice at very low frequencies. We observed concordant reductions of the naïve αβ T cell and iNKT pools in the periphery of young adult mice. Furthermore, we detected T cell infiltration in salivary and lacrimal glands, indicating defects in T cell tolerance.
Project description:Thymic epithelial cells (TEC) control T cell development and play essential roles in establishing self-tolerance. Transcription factors controlling TEC development are poorly characterized. We report that Klf6 plays a critical role in TEC development. Mice deficient for Klf6 in TEC had a hypoplastic thymus - evident from fetal stages into adulthood. Proliferation of TEC was not reduced, but a dramatic increase in the frequency of apoptotic TEC in fetal and adult thymus was observed. Among cortical TEC (cTEC), we found expansion of a previously unreported cTEC population expressing the transcription factor Sox10. Medullary TEC (mTEC) subsets were not equally impacted with Ccl21a+ mTEC I and Tuft-like mTEC IV being disproportionately affected. Consistent with these TEC defects, naïve conventional T cells and NKT cells were reduced in the spleen, and signs of autoimmunity were evident. Thus, Klf6 has a pro- survival role in TEC and is also required for differentiation of the mTEC I and mTEC IV populations of TEC in adult mice. In this work, we report that mice with Foxn1-Cre mediated ablation of Klf6 in TEC demonstrate thymic hypoplasia beginning from prenatal life and extending through adulthood. Guided by single-cell transcriptional profiling, we determined that loss of Klf6 increased programmed cell death of TEC in prenatal and adult mice. In adult mice, thymic Klf6 deficiency severely impacted the mTEC I and mTEC IV populations. In addition, Klf6 deficiency led to the expansion of a previously uncharacterized cTEC population expressing Sox10 that is present in wild-type mice at very low frequencies. We observed concordant reductions of the naïve αβ T cell and iNKT pools in the periphery of young adult mice. Furthermore, we detected T cell infiltration in salivary and lacrimal glands, indicating defects in T cell tolerance.
Project description:Thymic epithelial tumors are a group of neoplasms with heterogeneous histological features and clinical behavior. The identification of markers useful to predict patient prognosis and molecular targets for therapies is limited by a very little understanding of the biology of these neoplasms. We evaluated the copy number (CN) aberrations of genes involved in normal thymus development in thymic epithelial tumors, following the intriguing idea that the ectopic deregulation of genes relevant for proliferation and differentiation of embryonic cells, can contribute to tumor growth. Frequent CN losses of FOXC1 were observed in more aggressive tumors and correlated with a reduced protein expression; tumors negative for FOXC1 expression were associated with a shorter time to progression. In addition, FOXC1 showed tumor suppressor activity in in-vitro models. Our data indicate that FOXC1 loss can identify a group of thymic epithelial tumors with poor prognosis, possibly because its tumor suppressor properties. Two color array CGH of a series of 59 thymic epithelial tumors plus evaluation of 2 thymic carcinoma cell lines and one thymoma B1 cell line.
Project description:Thymic epithelial cells (TEC) control T cell development and play essential roles in establishing self-tolerance. By using Foxn1-Cre-driven ablation of Klf6 gene in TEC, we identified Klf6 as a critical factor in TEC development. Klf6 deficiency resulted in a hypoplastic thymus-evident from fetal stages into adulthood-in which a dramatic increase in the frequency of apoptotic TEC was observed. Among cortical TEC (cTEC), a previously unreported cTEC population expressing the transcription factor Sox10 was relatively expanded. Within medullary TEC (mTEC), mTEC I and Tuft-like mTEC IV were disproportionately decreased. Klf6 deficiency altered chromatin accessibility and affected TEC chromatin configuration. Consistent with these defects, naïve conventional T cells and invariant natural killer T cells were reduced in the spleen. Late stages of T cell receptor-dependent selection of thymocytes were affected, and mice exhibited autoimmunity. Thus, Klf6 has a prosurvival role and affects the development of specific TEC subsets contributing to thymic function.
Project description:Thymic epithelial tumors are a group of neoplasms with heterogeneous histological features and clinical behavior. The identification of markers useful to predict patient prognosis and molecular targets for therapies is limited by a very little understanding of the biology of these neoplasms. We evaluated the copy number (CN) aberrations of genes involved in normal thymus development in thymic epithelial tumors, following the intriguing idea that the ectopic deregulation of genes relevant for proliferation and differentiation of embryonic cells, can contribute to tumor growth. Frequent CN losses of FOXC1 were observed in more aggressive tumors and correlated with a reduced protein expression; tumors negative for FOXC1 expression were associated with a shorter time to progression. In addition, FOXC1 showed tumor suppressor activity in in-vitro models. Our data indicate that FOXC1 loss can identify a group of thymic epithelial tumors with poor prognosis, possibly because its tumor suppressor properties.
Project description:The thymus is one of the most affected organs during malnutrition, exhibiting atrophy and thymocyte depletion, characteristics that are also observed in several infectious diseases. The detrimental effects of malnutrition on immune responses to pathogens have long been recognized and it is considered a main risk factor for various infectious diseases, including visceral leishmaniasis (VL). However, the thymus has been barely studied during malnutrition and Leishmania infantum infection association. Protein malnutrition modifies intrathymic communication in L. infantum infected BALB/c mice by altering the abundance of proteins secreted to the thymic interstitial fluid (IF). We identified and compared protein abundance in the thymic IF samples from BALB/c mice that were fed with control protein (14%, CP) or low protein (4%, LP) isocaloric diets, followed by infection with L. infantum. By means of a quantitative proteomics approach using iTRAQ we identified 280 proteins of which 81% were reported as secreted by exosomes and 42% were previously described as secreted by thymic epithelial cells. LP-infected (LPi) animals showed a significant decrease in exosomal proteins, suggesting that exosomal carrier system is dysregulated in malnourished animals. LPi mice also exhibited an increase in the relative abundance of proteins involved in lipid metabolism and tricarboxylic acid cycle, suggestive of a non-proliferative microenvironment. Accordingly, flow cytometry analysis revealed that protein malnutrition decreases the proliferation of single positive and double positive T cells. Proteins engaged in glycolysis, protein ubiquitination and mRNA processing were significantly decreased. In addition, a significant decrease in the abundance of galectin-1 and increase of plasminogen were observed in malnourished animals. Together, the reduced cortical area, decreased proliferation, increased abundance of lipid- and tricarboxylic acid cycle-related proteins, and altered abundance of galectin-1 and plasminogen indicate a dysfunctional thymic microenvironment, where T cell migration, proliferation and maturation are compromised, contributing for the thymic atrophy observed in malnourished animals. All these alterations affect the control of the local and systemic infection, resulting in an impaired response to L. infantum infection.
Project description:Methylation microarray data (Illumina 850K) of 52 thymic epithelial tumors. 13 patients with thymoma A and B, 32 thymic carcinoma (TC) and 7 neuroendocrine tumors of the thymus (NET).