Biology subjects

Mucida, D.

Publications and source records attributed to Mucida, D..

28 records · Page 2Linked to original sources

bioRxiv2020

Antigen-specific induction of CD4+CD8αα+ intraepithelial T lymphocytes byBacteroidetes species

The microbiome contributes to the development and maturation of the immune system1-3 In response to commensal bacteria, CD4+ T cells can differentiate into distinct functional subtypes with regulatory or effector functions along the intestine. Peripherally-induced Foxp3+-regulatory T cells (pTregs) maintain immune homeostasis at the intestinal mucosa by regulating effector T cell responses against dietary antigens and microbes4. Similarly to pTregs, a subset of small intestine intraepithelial lymphocytes CD4+CD8+ (CD4IELS) exhibit regulatory properties and promote tolerance against dietary antigens5. Development of CD4IELS from conventional CD4+ T cells or from Treg precursors depends on the microbiota5,6. However, the identity of the microbial antigens recognized by CD4IELs remains unknown. We identified species belonging to the Bacteroidetes phylum as commensal bacteria capable of generating CD4IEL from naive CD4+ T cells expressing the pTreg transnuclear (TN) monoclonal TCR6 as well as from polyclonal WT T cells. We found that {beta}-hexosaminidase, a widely conserved carbohydrate-metabolizing enzyme in the Bacteroidetes phylum, is recognized by TN T cells, which share their TCR specificity with CD4+ T cells found in the intraepithelial compartment of polyclonal specific-pathogen-free (SPF) mice. In a mouse model of colitis, {beta}-hexosaminidase-specific CD4IELs provided protection from ulceration of the colon and weight loss. Thus, a single T cell clone can recognize a variety of abundant commensal bacteria and elicit a regulatory immune response at the intestinal epithelial surface.

immunology↗

bioRxiv2020

T cell receptor is required for differentiation but not maintenance of intestinal intraepithelial lymphocytes

The gut epithelium is populated by intraepithelial lymphocytes (IELs), a heterogeneous T cell population with cytotoxic and regulatory properties. Migrating peripheral CD4+ T cells, including regulatory (Treg) and conventional T cells (Tconv), acquire an IEL (CD4-IEL) program upon arrival at the epithelium. However, the specific role of the T cell receptor (TCR) in this process remains unclear. Single-cell TCR repertoire and transcriptomic analysis of intraepithelial CD4+ T cells revealed different extents of clonal expansion and TCR overlap between cell states; fully differentiated CD4-IELs from Tregs or Tconvs were the least diverse. Conditional deletion of TCR on differentiating CD4+ T cells or of MHCII on intestinal epithelial cells prevented CD4-IEL differentiation. However, TCR ablation on developed CD4-IELs did not affect their accumulation. These results indicate that local recognition of a limited set of antigens is an essential signal for the differentiation and adaptation of T cells to the epithelium.

immunology↗

bioRxiv2020

Stepwise chromatin and transcriptional acquisition of an intraepithelial lymphocyte program

Mesenteric lymph node (mLN) T cells undergo tissue adaptation upon migrating to intestinal lamina propria (LP) and intraepithelial (IE) compartments, ensuring appropriate balance between tolerance and resistance. By combining mouse genetics with single-cell and chromatin analyses, we addressed the molecular imprinting of gut epithelium on T cells. Transcriptionally, conventional and regulatory (Treg) CD4+ T cells from mLN, LP and IE segregate based on the gut layer they occupy; trajectory analysis suggests a stepwise loss of CD4-programming and acquisition of an intraepithelial profile. Treg fate-mapping coupled with RNA- and ATAC-sequencing revealed that the Treg program shuts down before an intraepithelial program becomes fully accessible at the epithelium. Ablation of CD4 lineage-defining transcription factor ThPOK results in premature acquisition of an IEL profile by mLN Tregs, partially recapitulating epithelium imprinting. Thus, coordinated replacement of circulating lymphocyte program with site-specific transcriptional and chromatin changes is necessary for tissue imprinting.

immunology↗

bioRxiv2020

Microbiota-modulated enteric neuron translational profiling uncovers a CART+ glucoregulatory subset

Microbial density and diversity increase towards the distal intestine, affecting tissue physiology, metabolism, and function of both immune and nervous systems. Intrinsic enteric-associated neurons (iEAN) continuously monitor and modulate intestinal functions, including nutrient absorption and motility. Through molecular, anatomic and functional approaches, we characterized the influence of the microbiota on iEAN. We found that iEAN are functionally adapted to the intestinal segment they occupy, with a stronger microbiota influence on distal intestine neurons. Chemogenetic characterization of microbiota-influenced iEAN identified a subset of viscerofugal CART+ neurons, enriched in the distal intestine, able to modulate feeding through insulin-glucose levels. Retro- and anterograde tracing revealed that CART+ viscerofugal neurons send axons to the gut sympathetic ganglion and are synaptically connected to the liver and pancreas. Our results demonstrate a region-specific adaptation of enteric neurons and indicate that specific iEAN subsets are capable of regulating host physiology independently from the central nervous system. One Sentence SummaryMicrobes impact regionally defined intrinsic enteric neuron translatomes, including a novel CART+ glucoregulatory viscerofugal population.

neuroscience↗

bioRxiv2019

Adrenergic signaling in muscularis macrophages limits neuronal death following enteric infection

Enteric-associated neurons (EANs) are closely associated with immune cells and continuously monitor and modulate homeostatic intestinal functions, including motility. Bidirectional interactions between immune and neuronal cells are altered during disease processes such as neurodegeneration or irritable bowel syndrome. We investigated how infection-induced inflammation affects intrinsic EANs and the role of intestinal muscularis macrophages (MMs) in this process. Using murine model of bacterial infection, we observed long-term gastrointestinal symptoms including reduced motility and subtype-specific neuronal loss. Neuronal-specific translational-profiling uncovered a caspase 11-dependent EAN cell-death mechanism induced by enteric infections. MMs responded to luminal infection by upregulating a neuroprotective program; gain- and loss-of-function experiments indicated that {beta}2-adrenergic receptor ({beta}2-AR) signaling in MMs mediates neuronal protection during infection via an arginase 1-polyamine axis. Our results identify a mechanism of neuronal cell death post-infection and point to a role for tissue-resident MMs in limiting neuronal damage.

immunology↗

bioRxiv2019

Microbiota imprint gut-intrinsic neuronal programming and sympathetic activity

Microbial density and diversity increases from proximal to distal regions of the intestine, affecting tissue physiology, metabolism, and function of the immune and nervous systems. Both intrinsic and extrinsic enteric-associated neurons (EAN) continuously monitor and modulate homeostatic intestinal functions, including nutrient absorption and motility. However, a systemic and circuit-based link between gut microbes and the nervous system has yet to be established. Through a combination of molecular, anatomic and functional approaches, we characterized the influence of the microbiota on EAN. We found that intrinsic EAN are functionally adapted to the specific intestinal region they occupy in a microbiota-dependent manner. Furthermore, we observed that gut-extrinsic sympathetic neurons are hyperactivated in the absence of microbes, while the production of butyrate is sufficient to suppress sympathetic activity. Finally, retrograde polysynaptic neuronal tracing from the intestinal wall revealed that brainstem GABAergic neurons are a potential central hub for modulation of gut-specific sympathetic neurons. These results reveal that commensal microbiota imprint gut-intrinsic neuronal gene programs and control extrinsic sympathetic activity through a metabolite-mediated gut-brain circuit.

neuroscience↗

bioRxiv2018

Vasculature-associated adipose tissue macrophages dynamically adapt to inflammatory and metabolic challenges

Tissue-resident macrophages comprise the most abundant immune cell population in healthy adipose tissue. Adipose tissue macrophage populations change during metabolic stress and ageing, and are thought to contribute to the pathogenesis of obesity. Here, we studied adipose tissue macrophage subpopulations in the steady state, and in response to nutritional and infectious challenges.\n\nUsing comprehensive cell-surface-based and gene expression analyses, we found that tissue-resident macrophages from healthy epididymal white adipose tissue (eWAT) tightly associate with blood vessels, displaying a very high endocytic capacity. We refer to these cells as Vasculature-associated Adipose tissue Macrophages (VAMs). Chronic high fat diet (HFD) feeding results in the accumulation of a monocyte-derived CD11c+CD64+ double positive (DP) macrophage eWAT population with a predominant anti-inflammatory gene profile, but reduced endocytic function. In contrast, fasting rapidly and reversibly leads to VAM depletion, while acute inflammatory stress induced by pathogens transiently depletes VAMs and simultaneously boosts DP macrophage accumulation. Our results indicate that adipose tissue macrophage populations adapt to metabolic stress and inflammation, suggesting an important role for these cells in restoring homeostasis.

immunology↗

bioRxiv2018

Compartmentalized lymph node drainage dictates intestinal adaptive immune responses

The intestinal immune system has the challenging task of tolerating foreign nutrients and the commensal microbiome, while excluding or eliminating ingested pathogens. Failure in such balance leads to a range of severe intestinal and systemic diseases such as inflammatory bowel diseases, food allergies or invasive gastrointestinal infections1,2. Multiple innate and adaptive immune mechanisms are therefore in place to maintain tissue integrity, including efficient peripheral generation of effector T (TH) cells and FOXP3+ regulatory T (pTreg) cells, which mediate resistance to pathogens and regulate excessive immune activation, respectively2-5. The gut-draining mesenteric lymph nodes (mLNs) are critical sites for orchestrating adaptive immunity to luminal perturbations6-8. However, how they manage to simultaneously support tolerogenic and inflammatory reactions is incompletely understood. Here we report that individual mLNs are anatomically and immunologically distinct according to the functional gut segment they drain. Dendritic cell gene signatures and adaptive T cell polarization against the same luminal antigen differed between mLNs along the intestine, the proximal small intestine-draining mLNs preferentially giving rise to tolerogenic and the distal mLNs to pro-inflammatory T cell responses. This compartmentalized dichotomy could be perturbed by duodenal infection, surgical removal of select distal mLNs, dysbiosis, or ectopic antigen delivery, impacting both lymphoid organ and tissue immune responses. Our findings reveal that the conflict between tolerogenic and inflammatory adaptive responses is in part resolved by discrete mLN drainage, and encourage gut segment-specific antigen targeting for therapeutic immune modulation.

immunology↗

bioRxiv2017

Intestinal epithelial and intraepithelial T cell crosstalk mediates a dynamic response to infection

Intestinal intraepithelial lymphocytes (IELs) are located at the critical interface between the intestinal lumen, which is chronically exposed to food and microbes, and the core of the body. Using high-resolution microscopy techniques and intersectional genetic tools, we investigated the nature of IEL responses to luminal microbes. We observed that TCR{gamma}{delta} IELs exhibit distinct location and movement patterns in the epithelial compartment that were microbiota-dependent and quickly altered upon enteric infections. These infection-induced changes included increased inter-epithelial cell (EC) scanning, anti-microbial gene expression and glycolysis. Direct modulation of glycolysis was sufficient to change {gamma}{delta} IEL behavior and susceptibility to early pathogen invasion. Both {gamma}{delta} IEL behavioral and metabolic changes were dependent on EC pathogen sensing. Our results uncover a coordinated EC-IEL response to enteric infections that modulates lymphocyte energy utilization and dynamics and supports maintenance of the intestinal epithelial barrier.

immunology↗

bioRxiv2017

Tissue adaptation: implications for gut immunity and tolerance

Tissue adaptation is an intrinsic component of immune cell development, influencing both resistance to pathogens and tolerance. Chronically stimulated surfaces of the body, in particular the gut mucosa, are the major sites where immune cells traffic and reside. Their adaptation to these environments requires constant discrimination between natural stimulation coming from harmless microbiota and food, and pathogens that need to be cleared. This review will focus on the adaptation of lymphocytes to the gut mucosa, a highly specialized environment that can help us understand the plasticity of leukocytes arriving at various tissue sites and how tissue-related factors operate to shape immune cell fate and function.

immunology↗