Project description:Innate lymphoid cells (ILC) in the small intestine govern immune homeostasis and protect the host against gut pathogens. While distinct cell-intrinsic signals have been identified that determine ILC development and differentiation, it has remained unclear which cell population regulates ILC sustenance. Using unbiased single cell RNA transcriptomic analysis of intestinal fibroblasts, we have identified a specialized Ccl19-expressing fibroblastic reticular cell (FRC) population that underpins solitary intestinal lymphoid tissue (SILT) structures including cryptopatches and isolated lymphoid follicles. Conditional ablation of lymphotoxin-β receptor (LTβR) signalling in SILT FRC impeded the maturation of isolated lymphoid follicles and blocked ILC maintenance through the downregulation of IL-7, consequently resulting in the elevated susceptibility to bacterial infection. Moreover, specific Ltbr ablation in FRC during adulthood revealed that constant LTβR-dependent FRC-ILC interaction is required to maintain SILT structures and ILC populations. Taken together, our study unveils a critical intestinal FRC niche that secures protective gut immunity.
Project description:Innate lymphoid cells (ILC) in the small intestine govern immune homeostasis and protect the host against gut pathogens. While distinct cell-intrinsic signals have been identified that determine ILC development and differentiation, it has remained unclear which cell population regulates ILC sustenance. Using unbiased single cell RNA transcriptomic analysis of intestinal fibroblasts, we have identified a specialized Ccl19-expressing fibroblastic reticular cell (FRC) population that underpins solitary intestinal lymphoid tissue (SILT) structures including cryptopatches and isolated lymphoid follicles. Conditional ablation of lymphotoxin-β receptor (LTβR) signalling in SILT FRC impeded the maturation of isolated lymphoid follicles and blocked ILC maintenance through the downregulation of IL-7, consequently resulting in the elevated susceptibility to bacterial infection. Moreover, specific Ltbr ablation in FRC during adulthood revealed that constant LTβR-dependent FRC-ILC interaction is required to maintain SILT structures and ILC populations. Taken together, our study unveils a critical intestinal FRC niche that secures protective gut immunity.
Project description:Innate lymphoid cells (ILC) are tissue-resident effector cells with important roles in tissue homeostasis, protective immunity and inflammatory disease. Here we investigated the role of the transcription factor Bcl6 in small intestinal innate lymphoid cells. Specifically, we performed single-cell RNA-seq on total small intestine lamina propria ILCs from tamoxifen-treated Id2-CreERT2 ROSA26-tdRFP Bcl6-fl/fl mice and Id2-CreERT2 ROSA26-tdRFP controls.
Project description:Signals from sympathetic neurons and immune cells regulate adipocytes contributing to fat tissue biology. Interactions between the nervous and immune systems have recently emerged as major regulators of host defence and inflammation1-4. Nevertheless, whether neuronal and immune cells cooperate in brain-body axes to orchestrate metabolism and obesity remains elusive. Here we report a novel neuro-mesenchyme unit that controls group 2 innate lymphoid cells (ILC2), adipose tissue physiology, metabolism and obesity via a brain-adipose circuit. We found that sympathetic nerve terminals act on neighbouring adipose mesenchymal cells via the beta-2 adrenergic receptor to control the expression of the glial-derived neurotrophic factor (GDNF) and the activity of ILC2 in gonadal fat. Accordingly, ILC2-autonomous manipulation of the GDNF receptor machinery led to altered ILC2 function, energy expenditure, insulin resistance and propensity to obesity. Retrograde tracing, chemical, surgical and chemogenetic manipulations identified a sympathetic aorticorenal circuit that modulates gonadal fat ILC2 and connects to high-order brain areas, including the paraventricular nucleus of the hypothalamus (PVH). Our work decodes a neuro-mesenchymal unit that translates long-range neuronal circuitry cues into adipose-resident ILC2 function, shaping the host metabolism and obesity.
Project description:Signals from sympathetic neurons and immune cells regulate adipocytes contributing to fat tissue biology. Interactions between the nervous and immune systems have recently emerged as major regulators of host defence and inflammation1-4. Nevertheless, whether neuronal and immune cells cooperate in brain-body axes to orchestrate metabolism and obesity remains elusive. Here we report a novel neuro-mesenchyme unit that controls group 2 innate lymphoid cells (ILC2), adipose tissue physiology, metabolism and obesity via a brain-adipose circuit. We found that sympathetic nerve terminals act on neighbouring adipose mesenchymal cells via the beta-2 adrenergic receptor to control the expression of the glial-derived neurotrophic factor (GDNF) and the activity of ILC2 in gonadal fat. Accordingly, ILC2-autonomous manipulation of the GDNF receptor machinery led to altered ILC2 function, energy expenditure, insulin resistance and propensity to obesity. Retrograde tracing, chemical, surgical and chemogenetic manipulations identified a sympathetic aorticorenal circuit that modulates gonadal fat ILC2 and connects to high-order brain areas, including the paraventricular nucleus of the hypothalamus (PVH). Our work decodes a neuro-mesenchymal unit that translates long-range neuronal circuitry cues into adipose-resident ILC2 function, shaping the host metabolism and obesity.
Project description:Small intestinal group 3 innate lymphoid cells (ILC3) from ILC3-conditional BMAL1 knock out mice or littermate control mice were sort-purified for transcriptional analysis
Project description:The maintenance of intestinal homeostasis is a fundamental process critical for organismal integrity. Sitting at the interface of the gut microbiome and mucosal immunity, adaptive and innate lymphoid populations regulate the balance between commensal micro-organisms and pathogens. Checkpoint inhibitors (CPI), particularly those targeting the CTLA-4 pathway, disrupt this fine balance and can lead to inflammatory bowel disease (IBD) and immune checkpoint colitis (CPI-C). Here, we show that CTLA-4 is expressed by innate lymphoid cells (ILC) and that its expression is regulated by ILC subset-specific cytokine cues in a microbiota-dependent manner. Genetic deletion or antibody blockade of CTLA-4 demonstrates that this pathway plays a key role in intestinal homeostasis and is conserved in human IBD and CPI-induced colitis (CPI-C). We propose that this population of CTLA-4-positive ILC may serve as an important target for the treatment of idiopathic and iatrogenic intestinal inflammation.
Project description:Group 3 innate lymphoid cells (ILC3s) are crucial for the maintenance of host-microbiota homeostasis in gastrointestinal mucosal tissues. The mechanisms that maintain lineage identity of intestinal ILC3s, and ILC3s-mediated orchestration of microbiota and mucosal T cell immunity are elusive. Here, we identified BATF as a gatekeeper of ILC3s homeostasis in the gut. Depletion of BATF in ILC3s resulted in excessive interferon-γ production, dysbiosis, aberrant T cell immune responses and spontaneous inflammatory bowel disease (IBD), which was considerably ameliorated by removal of adaptive immunity or antibiotic treatment. Mechanistically, BATF directly regulates ILC3s identity by globally shapes chromatin landscape of ILC3s. BATF directly binds to the cis-regulatory elements of type 1 effector genes, restrains their chromatin accessibility and inhibits their expression. Conversely, BATF promotes chromatin accessibility of genes involved in MHCII antigen processing and presentation pathways. Collectively, our findings reveal BATF is a promising candidate to maintain ILC3s stability and coordinate ILC3s–mediated control of intestinal homeostasis.
Project description:Group 3 innate lymphoid cells (ILC3s) are crucial for the maintenance of host-microbiota homeostasis in gastrointestinal mucosal tissues. The mechanisms that maintain lineage identity of intestinal ILC3s, and ILC3s-mediated orchestration of microbiota and mucosal T cell immunity are elusive. Here, we identified BATF as a gatekeeper of ILC3s homeostasis in the gut. Depletion of BATF in ILC3s resulted in excessive interferon-γ production, dysbiosis, aberrant T cell immune responses and spontaneous inflammatory bowel disease (IBD), which was considerably ameliorated by removal of adaptive immunity or antibiotic treatment. Mechanistically, BATF directly regulates ILC3s identity by globally shapes chromatin landscape of ILC3s. BATF directly binds to the cis-regulatory elements of type 1 effector genes, restrains their chromatin accessibility and inhibits their expression. Conversely, BATF promotes chromatin accessibility of genes involved in MHCII antigen processing and presentation pathways. Collectively, our findings reveal BATF is a promising candidate to maintain ILC3s stability and coordinate ILC3s–mediated control of intestinal homeostasis.