Commensal protists regulate intestinal CD8+ T cells to shape mucosal immune memory
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ABSTRACT: Tissue and microbial cues regulate the abundance and function of CD8+ T cells at barrier sites, yet the impact of specific microbes on their long-term durability remains unclear. Here, we show that the commensal protist Tritrichomonas musculus (T. mu) depletes intestinal CD8+ T cells, particularly tissue resident memory (TRM) cells, through activation of localized type 2 immunity. Colonization with T. mu or administration of its major secreted metabolite, succinate, led to the rapid decline of intestinal CD8+ T cells but left systemic memory T cells unaffected. The purinergic receptor, P2RX7, is highly expressed by intestinal TRMs and chemical antagonism of this receptor markedly restored CD8+ T cells during succinate feeding. Using lymphocytic choriomeningitis virus (LCMV) infection to track antigen-specific CD8+ memory T cells, we found viral-specific CD8+ TRMs repopulate the intestine independent of LCMV reinfection after removal of succinate treatment. These findings highlight how commensal protists and their metabolites reset homeostatic CD8+ T cell carrying capacity through damage-independent stimulation of TRM apoptosis and regulate mucosal memory.
Project description:Tissue resident memory T cells (TRM) provide superior protection against infection localised to extra-lymphoid compartments in the body. Here we show that CD103+CD8+ TRM cells develop in skin from killer cell lectin-like receptor (KLR)G1-negative precursors that selectively infiltrate the epithelial layer. In the skin, a combination of chemokine-guided epithelial entry, local interleukin (IL)-15 and transforming growth factor (TGF)-β signalling is required for formation and survival of these long-lived memory cells. Importantly, TRM differentiation results in the gradual acquisition of a unique transcriptional profile that differs from that expressed by memory cells in the circulation and other types of skin-resident intra-epithelial T cells, such as the dendritic epidermal T cells (DETC). We provide a comprehensive molecular and developmental framework for the local differentiation of a distinct type of peripheral memory T cell that contributes to an important first-line of immune defence in barrier tissues such as skin and mucosa. 24 samples were analyzed: 3 replicates of memory gB-T CD8+. CD103+ T cells isolated from the skin of C57/BL6 mice on day 30 p.i. with HSV KOS. 3 replicates of memory P14 CD8+ T cells isolated from gut of mice on day 60 p.i. with LCMV Armstrong. 3 replicates of memory gB-T CD8+ T cells from the lung of mice on day 30 p.i. with influenza WSN. 3 replicates of memory CD62L high CD8+ T cells from the spleen of mice on day 30 p.i. with HSV KOS. 3 replicates of memory CD62L low CD8+ T cells from the spleen of mice of day 30 p.i. with HSV KOS. 3 replicates of γδ-DETC isolated from the skin of C57/BL6 mice on day 30 p.i. with HSV KOS. 3 replicates of αβ-DETC from naive TCRδ-/- mice; and 3 replicates of naive gB-T CD8+ T cells from the spleen of naive gB-T transgenic mice.
Project description:Tissue-resident memory T (TRM) cells provide key adaptive immune responses in infection, cancer, and autoimmunity. However transcriptional heterogeneity of human intestinal TRM cells remains undefined. Here, we investigated transcriptional and functional heterogeneity of human TRM cells through study of donor-derived intestinal TRM cells from intestinal transplant recipients. Single-cell transcriptional profiling identified two distinct transcriptional states of CD8+ TRM cells, delineated by ITGAE and ITGB2 expression. We defined a transcriptional signature discriminating these two CD8+ populations, including differential expression of cytotoxicity- and residency-associated genes. Flow cytometry of recipient-derived cells infiltrating the graft and lymphocytes from healthy gut confirmed the two CD8+ TRM phenotypes. CD103+ CD8+ TRM cells produced IL-2, and demonstrated greater polyfunctional cytokine production, while β2-integrin+ CD69+ CD103- TRM cells had higher granzyme expression. Phenotypic and functional analysis of intestinal CD4+ T cells identified many parallels, including a distinct β2-integrin+ population. Together, these results describe the transcriptional, phenotypic, and functional heterogeneity of human intestinal CD4+ and CD8+ TRM cells.
Project description:Tissue-resident memory T (TRM) cells provide key adaptive immune responses in infection, cancer, and autoimmunity. However transcriptional heterogeneity of human intestinal TRM cells remains undefined. Here, we investigated transcriptional and functional heterogeneity of human TRM cells through study of donor-derived intestinal TRM cells from intestinal transplant recipients. Single-cell transcriptional profiling identified two distinct transcriptional states of CD8+ TRM cells, delineated by ITGAE and ITGB2 expression. We defined a transcriptional signature discriminating these two CD8+ populations, including differential expression of cytotoxicity- and residency-associated genes. Flow cytometry of recipient-derived cells infiltrating the graft and lymphocytes from healthy gut confirmed the two CD8+ TRM phenotypes. CD103+ CD8+ TRM cells produced IL-2, and demonstrated greater polyfunctional cytokine production, while β2-integrin+ CD69+ CD103- TRM cells had higher granzyme expression. Phenotypic and functional analysis of intestinal CD4+ T cells identified many parallels, including a distinct β2-integrin+ population. Together, these results describe the transcriptional, phenotypic, and functional heterogeneity of human intestinal CD4+ and CD8+ TRM cells.
Project description:During acute infections, CD8+ T cells form various memory subpopulations to provide long-lasting protection against reinfection. Central memory (TCM), Effector memory (TEM), and long-lived effector (LLE) cells are circulating memory populations with distinct plasticity, migration patterns, and effector functions. Tissue-resident memory (TRM) cells permanently reside in the frontline sites of pathogen entry and provide tissue-specific protection upon reinfection. Here, using scRNA-seq and bulk RNA-seq, we examined the different and shared transcriptomes and regulators of TRMs with other circulating memory populations. Furthermore, we identified heterogeneity within the TRM pool from small intestine and novel transcriptional regulators that may control the phenotypic and functional heterogeneity of TRM cells during acute infection. Our findings provide a resource for future studies to identify novel pathways for enhancing vaccination and immunotherapeutic approaches.
Project description:During acute infections, CD8+ T cells form various memory subpopulations to provide long-lasting protection against reinfection. Central memory (TCM), Effector memory (TEM), and long-lived effector (LLE) cells are circulating memory populations with distinct plasticity, migration patterns, and effector functions. Tissue-resident memory (TRM) cells permanently reside in the frontline sites of pathogen entry and provide tissue-specific protection upon reinfection. Here, using scRNA-seq and bulk RNA-seq, we examined the different and shared transcriptomes and regulators of TRMs with other circulating memory populations. Furthermore, we identified heterogeneity within the TRM pool from small intestine and novel transcriptional regulators that may control the phenotypic and functional heterogeneity of TRM cells during acute infection. Our findings provide a resource for future studies to identify novel pathways for enhancing vaccination and immunotherapeutic approaches.
Project description:Tissue resident memory (Trm) represent a newly described memory T cell population. We have previously characterized a population of Trm that persists within the brain following acute virus infection. Although capable of providing marked protection against a subsequent local challenge, brain Trm do not undergo recall expansion following dissociation from the tissue. Furthermore, these Trm do not depend on the same survival factors as the circulating memory T cell pool as assessed either in vivo or in vitro. To gain greater insight into this population of cells we compared the gene-expression profiles of Trm isolated from the brain to circulating memory T cells isolated from the spleen following an acute virus infection. Trm displayed altered expression of genes involved in chemotaxis, expressed a distinct set of transcription factors and overexpressed several inhibitory receptors. Cumulatively, these data indicates that Trm are a distinct memory T cell population disconnected from the circulating memory T cell pool and displaying a unique molecular signature which likely results in optimal survival and function within their local environment. 13 samples were analyzed: 5 replicates of memory OT-I CD8+.CD103- T cells isolated from the spleen of mice on day 20 p.i. with VSV-OVA. 5 replicates of memory OT-I CD8+CD103+ T cells isolated from the brain of mice on day 20 p.i. with VSV-OVA; and 3 replicates of memory OT-I.CD8+ CD103- T cells isolated from the brain of mice on day 20 p.i. with VSV-OVA
Project description:Although resident memory T cells (TRMs), which are memory T cells that are retained locally within tissues, have recently been described as antigen-specific frontline defenders against pathogens in barrier and non-barrier epithelial tissues, they have also been noted for perpetuating chronic inflammation. Furthermore, the conditions responsible for TRM differentiation are still poorly understood, and their contributions, if any, to sterile models of chronic kidney disease (CKD) remain a mystery. In this study we identify a substantial population of TRMs in the kidneys of mice with aristolochic acid (AA)-induced CKD. Flow cytometry of injured kidneys showed T cells bearing TRM surface markers and single cell RNA sequencing revealed these cells as expressing well-known TRM transcription factors and receptors responsible for TRM differentiation and maintenance. While kidney TRMs expressed Cd44, a marker of antigen experience and T cell activation, their derivation was surprisingly independent of cognate antigen-T cell receptor interactions, as the kidneys of transgenic OT-1 mice still harbored considerable proportions of TRMs after injury. Our results suggest a non-antigen-specific or antigen-independent mechanism capable of generating TRMs in the kidney and highlight the need to better understand TRMs and their involvement in CKD.
Project description:The networks of transcription factors (TFs) that control multipotency versus effector programs in intestinal resident memory T (TRM) cells are poorly understood. Mice with post-activation, conditional deletion of the TF Bcl11b in CD8+ T cells, infected with a food-born pathogen, had increased numbers of intestinal TRM cells, and their precursors and decreased splenic effector cells and circulating memory cells and precursors. Loss of circulating memory cells was in part due to increased intestinal homing of Bcl11b-/- circulating precursors with no major alterations in their programs. Bcl11b-/- memory CD8+ T cells had an impaired recall response despite their accumulation in the gut. Intestinal Bcl11b-/- TRM cells and their precursors manifested major alterations in the residency program, with diminished expression of multipotency program genes and upregulation of the effector program genes. Integration of transcriptomics with chromatin accessibility, activating histone marks and Bcl11b genome binding showed a link between the reduction in the multipotent program genes with regions of decreased chromatin accessibility and activating histone marks in Bcl11b-/- cells. In contrast, the effector program genes displayed increased activating epigenetic status. We propose that Bcl11b regulates tissue resident TRM program genes and is positioned upstream of Tcf1 and Blimp1 in regulation of multipotency versus effector TRM program, respectively. Rescuing experiments normalized the increased numbers of intestinal Bcl11b-/- TRM cells. Thus, Bcl11b is a frontrunner in the memory tissue residency program and acts early in lineage decision, promoting TRM cell multipotency and restricting effector function.
Project description:The networks of transcription factors (TFs) that control multipotency versus effector programs in intestinal resident memory T (TRM) cells are poorly understood. Mice with post-activation, conditional deletion of the TF Bcl11b in CD8+ T cells, infected with a food-born pathogen, had increased numbers of intestinal TRM cells, and their precursors and decreased splenic effector cells and circulating memory cells and precursors. Loss of circulating memory cells was in part due to increased intestinal homing of Bcl11b-/- circulating precursors with no major alterations in their programs. Bcl11b-/- memory CD8+ T cells had an impaired recall response despite their accumulation in the gut. Intestinal Bcl11b-/- TRM cells and their precursors manifested major alterations in the residency program, with diminished expression of multipotency program genes and upregulation of the effector program genes. Integration of transcriptomics with chromatin accessibility, activating histone marks and Bcl11b genome binding showed a link between the reduction in the multipotent program genes with regions of decreased chromatin accessibility and activating histone marks in Bcl11b-/- cells. In contrast, the effector program genes displayed increased activating epigenetic status. We propose that Bcl11b regulates tissue resident TRM program genes and is positioned upstream of Tcf1 and Blimp1 in regulation of multipotency versus effector TRM program, respectively. Rescuing experiments normalized the increased numbers of intestinal Bcl11b-/- TRM cells. Thus, Bcl11b is a frontrunner in the memory tissue residency program and acts early in lineage decision, promoting TRM cell multipotency and restricting effector function.
Project description:The networks of transcription factors (TFs) that control multipotency versus effector programs in intestinal resident memory T (TRM) cells are poorly understood. Mice with post-activation, conditional deletion of the TF Bcl11b in CD8+ T cells, infected with a food-born pathogen, had increased numbers of intestinal TRM cells, and their precursors and decreased splenic effector cells and circulating memory cells and precursors. Loss of circulating memory cells was in part due to increased intestinal homing of Bcl11b-/- circulating precursors with no major alterations in their programs. Bcl11b-/- memory CD8+ T cells had an impaired recall response despite their accumulation in the gut. Intestinal Bcl11b-/- TRM cells and their precursors manifested major alterations in the residency program, with diminished expression of multipotency program genes and upregulation of the effector program genes. Integration of transcriptomics with chromatin accessibility, activating histone marks and Bcl11b genome binding showed a link between the reduction in the multipotent program genes with regions of decreased chromatin accessibility and activating histone marks in Bcl11b-/- cells. In contrast, the effector program genes displayed increased activating epigenetic status. We propose that Bcl11b regulates tissue resident TRM program genes and is positioned upstream of Tcf1 and Blimp1 in regulation of multipotency versus effector TRM program, respectively. Rescuing experiments normalized the increased numbers of intestinal Bcl11b-/- TRM cells. Thus, Bcl11b is a frontrunner in the memory tissue residency program and acts early in lineage decision, promoting TRM cell multipotency and restricting effector function.