Aiolos modulates IL-15 responsiveness of intestinal intraepithelial lymphocytes [RNA-seq]
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ABSTRACT: Intestinal intraepithelial lymphocytes (IEL) are capable of rapid innate-like responses to microenvironmental cues. While poised to activation, IEL effector functions must be stringently controlled. Aiolos is an Ikaros zinc finger (IKZF) family member encoded by Ikzf3 that promotes histone deacetylation. Here, we found that Aiolos is a crucial regulator of IEL activation. Ikzf3–/– CD8αα+ IEL expressed high levels of innate NK receptors, cytotoxic enzymes, cytokines and chemokines. Single cell RNAseq of IEL revealed that Ikzf3 deficiency mostly amplified the effector machinery of a CD8αα+ IEL subset characterized by high expression CD122, the receptor for IL-15. Furthermore, Ikzf3 deficiency increased IEL responsiveness to IL-15. Aiolos binding sites were close to those for STAT5 and RUNX transcription factors that promote IL-15 signaling and cytolytic programs, respectively; lack of Ikzf3 increased accessibility and histone acetylation of these chromatin regions. Ikzf3 deficiency increased susceptibility to colitis, demonstrating the functional relevance of Aiolos-mediated regulation of IEL effector functions.
Project description:Intestinal intraepithelial lymphocytes (IEL) are capable of rapid innate-like responses to microenvironmental cues. While poised to activation, IEL effector functions must be stringently controlled. Aiolos is an Ikaros zinc finger (IKZF) family member encoded by Ikzf3 that promotes histone deacetylation. Here, we found that Aiolos is a crucial regulator of IEL activation. Ikzf3–/– CD8αα+ IEL expressed high levels of innate NK receptors, cytotoxic enzymes, cytokines and chemokines. Single cell RNAseq of IEL revealed that Ikzf3 deficiency mostly amplified the effector machinery of a CD8αα+ IEL subset characterized by high expression CD122, the receptor for IL-15. Furthermore, Ikzf3 deficiency increased IEL responsiveness to IL-15. Aiolos binding sites were close to those for STAT5 and RUNX transcription factors that promote IL-15 signaling and cytolytic programs, respectively; lack of Ikzf3 increased accessibility and histone acetylation of these chromatin regions. Ikzf3 deficiency increased susceptibility to colitis, demonstrating the functional relevance of Aiolos-mediated regulation of IEL effector functions.
Project description:Intestinal intraepithelial lymphocytes (IEL) are capable of rapid innate-like responses to microenvironmental cues. While poised to activation, IEL effector functions must be stringently controlled. Aiolos is an Ikaros zinc finger (IKZF) family member encoded by Ikzf3 that promotes histone deacetylation. Here, we found that Aiolos is a crucial regulator of IEL activation. Ikzf3–/– CD8αα+ IEL expressed high levels of innate NK receptors, cytotoxic enzymes, cytokines and chemokines. Single cell RNAseq of IEL revealed that Ikzf3 deficiency mostly amplified the effector machinery of a CD8αα+ IEL subset characterized by high expression CD122, the receptor for IL-15. Furthermore, Ikzf3 deficiency increased IEL responsiveness to IL-15. Aiolos binding sites were close to those for STAT5 and RUNX transcription factors that promote IL-15 signaling and cytolytic programs, respectively; lack of Ikzf3 increased accessibility and histone acetylation of these chromatin regions. Ikzf3 deficiency increased susceptibility to colitis, demonstrating the functional relevance of Aiolos-mediated regulation of IEL effector functions.
Project description:Intestinal intraepithelial lymphocytes (IEL) are capable of rapid innate-like responses to microenvironmental cues. While poised to activation, IEL effector functions must be stringently controlled. Aiolos is an Ikaros zinc finger (IKZF) family member encoded by Ikzf3 that promotes histone deacetylation. Here, we found that Aiolos is a crucial regulator of IEL activation. Ikzf3–/– CD8αα+ IEL expressed high levels of innate NK receptors, cytotoxic enzymes, cytokines and chemokines. Single cell RNAseq of IEL revealed that Ikzf3 deficiency mostly amplified the effector machinery of a CD8αα+ IEL subset characterized by high expression CD122, the receptor for IL-15. Furthermore, Ikzf3 deficiency increased IEL responsiveness to IL-15. Aiolos binding sites were close to those for STAT5 and RUNX transcription factors that promote IL-15 signaling and cytolytic programs, respectively; lack of Ikzf3 increased accessibility and histone acetylation of these chromatin regions. Ikzf3 deficiency increased susceptibility to colitis, demonstrating the functional relevance of Aiolos-mediated regulation of IEL effector functions.
Project description:Intestinal intraepithelial lymphocytes (IEL) are an abundant population of tissue-resident T cells that protect the gut from pathogens and maintain intestinal homeostasis. The cytokine IL-15 is trans-presented by epithelial cells to IEL in complex with the IL-15 receptor α chain (IL-15Rα) and plays essential roles both in maintaining IEL homeostasis, and in inducing IEL activation in response to epithelial stress. When overproduced, IL-15 is a key driver of the gluten-induced enteropathy Coeliac disease, through cytotoxic activation of IEL. To better understand how IL-15 directly regulates both homeostatic and inflammatory functions of IEL, we performed quantitative proteomics of IL-15/Rα-stimulated murine IEL, sorted into their 3 main subpopulations, TCRγδ CD8αα, TCRαβ CD8αβ and TCRαβ CD8αα expressing IEL. The data reveal that high IL-15/Rα stimulation licenses cell cycle activation, upregulates the biosynthetic machinery in IEL, increases mitochondrial respiratory capacity and induces expression of cell surface immune receptors and adhesion proteins that potentially drive IEL activation.
Project description:TCRαβ+CD8αα+ intraepithelial lymphocytes (CD8αα+ αβ IELs), a specialized subset of T cells in the gut epithelium, develop from thymic agonist-selected IEL precursors (IELps). The molecular mechanisms underlying the selection and differentiation of this T cell type in the thymus are largely unknown. Here, we found that Bcl6 deficiency in αβ T cells resulted in nearly the absence of CD8αα+ αβ IELs. BCL6 was expressed by approximately 50% of CD8αα+ αβ IELs but the majority thymic PD1+ IELps post agonist selection; its deficiency blocked early IELp generation in the thymus. Moreover, BCL6 expression in IELps was induced by thymic TCR signaling in an ERK-dependent manner. As a result of Bcl6 deficiency, the precursors of IELps among CD4+CD8+ double positive (DP) thymocytes exhibited increased apoptosis during agonist selection, and impaired IELp differentiation and maturation. Taken together, our results elucidate BCL6 as a crucial transcription factor during the thymic development of CD8αα+ αβ IELs.
Project description:A missense mutation (G158R) in Aiolos, encoded by Ikzf3 gene, resulted in defective generation of B cells in mice. Pre-B cells were profoundly decreased in homozygous mutant mice. Heterozygous mutant mice showed milder B cell developmental defects, and B cells in the secondary lymphoid organs decreased. Genome-wide binding of Aiolos and Ikaros were altered in the thymus of homozygous Ikzf3 G158R mice. Our findings indicate that Aiolos-G158R hinders B cell development by interfering Ikaros' function via formation of heterodimers. A heterozygous missense variant (G159R) in AIOLOS, encoded by IKZF3 gene, resulted in impaired adaptive immunity, which predominantly manifested as profound B cell developmental defect. Genome-wide binding of wild-type AIOLOS and AIOLOS G159R mutant were examined in IKZF3 knock-out human pre-B cell line NALM-6, retrovirally transduced with doxycycline inducible wild-type AIOLOS or AIOLOS G159R. Changes in genome-wide binding and binding motif were observed for AIOLOS G159R mutant.
Project description:To identify genes dysregulated by Aiolos N159S variant, splenic B cell and T cell populations of Ikzf3 +/+, Ikzf3 +/N159S and Ikzf3 N159S/N159S mice were subjected to RNA-seq analyses.
Project description:Intestinal intraepithelial T lymphocytes (T-IEL) patrol the single layer of epithelial cells lining the gut, and consist of both induced T-IEL, derived from systemic antigen-experienced lymphocytes, and natural IEL, that are developmentally targeted to the intestine. To gain functional insights into these enigmatic cells, we used high-resolution quantitative mass spectrometry to investigate the proteomic landscape of the main T-IEL populations in the gut. Comparing the proteomes of induced T-IEL, tissue-resident memory TCRαβ+ CD8αβ+ cells and natural TCRγδ+ CD8αα+ and TCRαβ+ CD8αα+ T-IEL, with naive CD8+ T cells from lymph nodes reveals striking similarities between T-IEL subsets and the dominant effect of the gut environment on T-IEL phenotypes. Analysis of copy numbers/cell of >7000 proteins provides new understanding of the differences in composition of T cell antigen receptor signal transduction pathways in T-IEL versus conventional T cells and reveals skewing of the metabolic machinery towards an exhausted T cell phenotype adapted to the intestinal environment. This study provides a resource for exploring and understanding how multiple inputs are integrated into T-IEL function.
Project description:A missense mutation (G158R) in Ikzf3 gene resulted in defective generation of B cells in mice. Pre-B cells were profoundly decreased in homozygous mutant mice. Heterozygous mutant mice showed milder B cell developmental defects, and decreased B cells in the secondary lymphoid organs were observed. Ikzf3 encodes Aiolos, which makes heterodimer with Ikaros. Our findings indicate that the loss-of-function mutation in Aiolos hinders B cell development by interfering Ikaros' function via formation of heterodimers.
Project description:T cell antigen-receptor (TCR) and cytokine receptor engagement trigger large changes in Serine/Threonine kinase signalling networks to drive T cell activation and differentiation. The role of only few kinase signalling pathways have been studied in detail, and in this context, Pim kinases are an interesting, yet understudied, family of Serine/Threonine kinases, with reported roles in key processes including survival, proliferation, metabolism across a range of cell types. T lymphocytes predominantly express PIM1 and PIM2, which are rapidly induced by TCR, costimulation and cytokine signalling. Using high-resolution mass spectrometry and RNAseq we systematically examine the impact of Pim1/Pim2 double deficiency on in vitro differentiated cytotoxic T lymphocytes (CTL) expanded in the cytokines IL-2 and IL-15 to generate effector or memory T cells respectively. We find that Pim kinases are dispensable for IL-15-driven memory cell differentiation, but that Pim1/2-deficiency has a selective impact on the transcriptome and proteome of IL-2 driven effector CD8 T cells. ~75% of Pim kinase-regulated proteins were not predicted by differences in mRNA in IL-2 expanded CTL. These included proteins that are key for effector cell function: glucose transporters SLC2A1 and SLC2A3 and key effector molecules Granzyme A and B. We find that Pim kinases have this effect via control of protein translation. Another key finding was that the mRNA for key T cell homing receptors Ccr7, S1pr1 and CD62L was increased in Pim1/2-deficienct T cells and that this functionally enhancing homing to secondary lymphoid organs.