Expression data from mouse small intestinal γδ intraepithelial lymphocytes
ABSTRACT: The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. In this study, we used microarrays to uncover the transcriptional responses that occur in small intestinal γδ intraepithelial lymphocytes following bacterial challenge. Overall design: γδ intraepithelial lymphocytes (γδ IEL) were isolated by flow cytometry from the small intestines of germ-free mice, or from age- and sex-matched conventionally-raised counterparts. We extracted RNAs from these purified γδ IEL for analysis on Affymetrix DNA microarrays. The mice were all >8 weeks in age, and each sample represents a pool of RNAs from 5-8 mice.
Project description:The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. In this study, we used microarrays to uncover the transcriptional responses that occur in small intestinal γδ intraepithelial lymphocytes following bacterial challenge. γδ intraepithelial lymphocytes (γδ IEL) were isolated by flow cytometry from the small intestines of germ-free mice, or from age- and sex-matched conventionally-raised counterparts. We extracted RNAs from these purified γδ IEL for analysis on Affymetrix DNA microarrays. The mice were all >8 weeks in age, and each sample represents a pool of RNAs from 5-8 mice.
Project description:Intraepithelial lymphocytes (IELs) expressing the γδ TCR (γδ IELs) provide continuous surveillance of the intestinal epithelium. However, the mechanisms regulating the basal motility of these cells within the epithelial compartment have not been well defined. We investigated whether IL-15 contributes to γδ IEL localization and migratory behavior in addition to its role in IEL differentiation and survival. Using advanced live cell imaging techniques in mice, we find that compartmentalized overexpression of IL-15 in the lamina propria shifts the distribution of γδ T cells from the epithelial compartment to the lamina propria. This mislocalization could be rescued by epithelial IL-15 overexpression, indicating that epithelial IL-15 is essential for γδ IEL migration into the epithelium. Furthermore, in vitro analyses demonstrated that exogenous IL-15 stimulates γδ IEL migration into cultured epithelial monolayers, and inhibition of IL-2Rβ significantly attenuates the basal motility of these cells. Intravital microscopy showed that impaired IL-2Rβ signaling induced γδ IEL idling within the lateral intercellular space, which resulted in increased early pathogen invasion. Similarly, the redistribution of γδ T cells to the lamina propria due to local IL-15 overproduction also enhanced bacterial translocation. These findings thus reveal a novel role for IL-15 in mediating γδ T cell localization within the intestinal mucosa and regulating γδ IEL motility and patrolling behavior as a critical component of host defense.
Project description:The mammalian gastrointestinal tract harbors thousands of bacterial species that include symbionts as well as potential pathogens. The immune responses that limit access of these bacteria to underlying tissue remain poorly defined. Here we show that ?? intraepithelial lymphocytes (?? IEL) of the small intestine produce innate antimicrobial factors in response to resident bacterial "pathobionts" that penetrate the intestinal epithelium. ?? IEL activation was dependent on epithelial cell-intrinsic MyD88, suggesting that epithelial cells supply microbe-dependent cues to ?? IEL. Finally, ?? T cells protect against invasion of intestinal tissues by resident bacteria specifically during the first few hours after bacterial encounter, indicating that ?? IEL occupy a unique temporal niche among intestinal immune defenses. Thus, ?? IEL detect the presence of invading bacteria through cross-talk with neighboring epithelial cells and are an essential component of the hierarchy of immune defenses that maintain homeostasis with the intestinal microbiota.
Project description:OBJECTIVES: Enteropathy associated T-cell lymphoma (EATL) is a rare non-Hodgkin lymphoma that may complicate coeliac disease and typically occurs in patients with refractoriness to the gluten-free diet. The majority of these patients harbour a clonal expansion of intraepithelial lymphocytes (IELs) with an aberrant phenotype in the small intestine which are thus considered as the 'precursor' lymphoma cells. We describe a 51-year-old female patient with refractory coeliac disease (RCD) who developed an EATL with manifestations in the proximal small intestine and in a mesenteric lymph node that did not evolve from regular type 'aberrant' αβ-T-cells but rather from a clonal expansion of γδ-T-cells. METHODS: Duodenal biopsies and lymphoma tissue from a patient with refractory coeliac disease whom developed an EATL were extensively studied by immunophenotypical, T-cell receptor immunogenetic and chromosomal analysis. RESULTS: Flow cytometric analysis of duodenal IELs revealed an unusual large clonal expansion of CD30 negative γδ-T-cells in a patient with RCD. When the patient clinically deteriorated 18 months later, a substantial part (30%) of this cell population did express CD30. In addition, identical immunogenetic aberrancies had developed in a prehepatic lymph node. CONCLUSIONS: We here report on a case of extraintestinal EATL that originated from a clonal γδ-IEL population rather than from aberrant IEL. This EATL displayed a distinctive pattern of immunophenotypical, T-cell receptor immunogenetic and chromosomal aberrancies as compared to classical EATL, defining this lymphoma as a novel variant of EATL.
Project description:The small intestine contains CD4+CD8??+ double-positive intraepithelial lymphocytes (DP IELs), which originate from intestinal CD4+ T cells through down-regulation of the transcription factor Thpok and have regulatory functions. DP IELs are absent in germ-free mice, which suggests that their differentiation depends on microbial factors. We found that DP IEL numbers in mice varied in different vivaria, correlating with the presence of Lactobacillus reuteri This species induced DP IELs in germ-free mice and conventionally-raised mice lacking these cells. L. reuteri did not shape the DP-IEL-TCR (TCR, T cell receptor) repertoire but generated indole derivatives of tryptophan that activated the aryl-hydrocarbon receptor in CD4+ T cells, allowing Thpok down-regulation and differentiation into DP IELs. Thus, L. reuteri, together with a tryptophan-rich diet, can reprogram intraepithelial CD4+ T cells into immunoregulatory T cells.
Project description:The gut microbiota impacts many aspects of host biology including immune function. One hypothesis is that microbial communities induce epigenetic changes with accompanying alterations in chromatin accessibility, providing a mechanism that allows a community to have sustained host effects even in the face of its structural or functional variation. We used ATAC-seq to define chromatin accessibility in predicted enhancer regions of intestinal αβ+ and γδ+ intraepithelial lymphocytes (IELs) purified from germ-free mice, their conventionally-raised (CONV-R) counterparts, and mice reared GF and then colonized with a CONV-R gut microbiota at the end of the suckling-weaning transition. Characterizing genes adjacent to traditional enhancers and super-enhancers revealed signaling networks, metabolic pathways, and enhancer-associated transcription factors affected by the microbiota. Our results support the notion that epigenetic modifications help define microbial community-affiliated functional features of host immune cell lineages. Overall design: We interrogated chromatin accessibility using ATAC-seq in four cell types derived from mice (CD4+ T cells, CD8+ T cells, αβ+ intraepithelial lymphocytes, and γδ+ intraepithelial lymphocytes), across three gut microbial colonization states (germ-free, conventionally-raised, and conventionalized).
Project description:?? intraepithelial lymphocytes (IELs) are located beneath or between adjacent intestinal epithelial cells and are thought to contribute to homeostasis and disease pathogenesis. Using in vivo microscopy to image jejunal mucosa of GFP ?? T-cell transgenic mice, we discovered that ?? IELs migrate actively within the intraepithelial compartment and into the lamina propria. As a result, each ?? IEL contacts multiple epithelial cells. Occludin is concentrated at sites of ?? IEL/epithelial interaction, where it forms a ring surrounding the ?? IEL. In vitro analyses showed that occludin is expressed by epithelial and ?? T cells and that occludin derived from both cell types contributes to these rings and to ?? IEL migration within epithelial monolayers. In vivo TNF administration, which results in epithelial occludin endocytosis, reduces ?? IEL migration. Further in vivo analyses demonstrated that occludin KO ?? T cells are defective in both initial accumulation and migration within the intraepithelial compartment. These data challenge the paradigm that ?? IELs are stationary in the intestinal epithelium and demonstrate that ?? IELs migrate dynamically to make extensive contacts with epithelial cells. The identification of occludin as an essential factor in ?? IEL migration provides insight into the molecular regulation of ?? IEL/epithelial interactions.
Project description:<h4>Background</h4>Gastrointestinal barrier immaturity predisposes preterm infants to necrotizing enterocolitis (NEC). Intraepithelial lymphocytes (IEL) bearing the unconventional T cell receptor (TCR) ?? (?? IEL) maintain intestinal integrity and prevent bacterial translocation in part through production of interleukin (IL) 17.<h4>Objective</h4>We sought to study the development of ?? IEL in the ileum of human infants and examine their role in NEC pathogenesis. We defined the ontogeny of ?? IEL proportions in murine and human intestine and subjected tcr?-/- mice to experimental gut injury. In addition, we used polychromatic flow cytometry to calculate percentages of viable IEL (defined as CD3+ CD8+ CD103+ lymphocytes) and the fraction of ?? IEL in surgically resected tissue from infants with NEC and gestational age matched non-NEC surgical controls.<h4>Results</h4>In human preterm infants, the proportion of IEL was reduced by 66% in 11 NEC ileum resections compared to 30 non-NEC controls (p<0.001). While ?? IEL dominated over conventional ?? IEL early in gestation in mice and in humans, ?? IEL were preferential decreased in the ileum of surgical NEC patients compared to non-NEC controls (50% reduction, p<0.05). Loss of IEL in human NEC was associated with downregulation of the Th17 transcription factor retinoic acid-related orphan nuclear hormone receptor C (RORC, p<0.001). TCR?-deficient mice showed increased severity of experimental gut injury (p<0.05) with higher TNF? expression but downregulation of IL17A.<h4>Conclusion</h4>Complimentary mouse and human data suggest a role of ?? IEL in IL17 production and intestinal barrier production early in life. Specific loss of the ?? IEL fraction may contribute to NEC pathogenesis. Nutritional or pharmacological interventions to support ?? IEL maintenance in the developing small intestine could serve as novel strategies for NEC prevention.
Project description:Unrelenting environmental challenges to the gut epithelium place particular demands on the local immune system. In this context, intestinal intraepithelial lymphocytes (IEL) compose a large, highly conserved T cell compartment, hypothesized to provide a first line of defence via cytolysis of dysregulated intestinal epithelial cells (IEC) and cytokine-mediated re-growth of healthy IEC. Here we show that one of the most conspicuous impacts of activated IEL on IEC is the functional upregulation of antiviral interferon (IFN)-responsive genes, mediated by the collective actions of IFNs with other cytokines. Indeed, IEL activation in vivo rapidly provoked type I/III IFN receptor-dependent upregulation of IFN-responsive genes in the villus epithelium. Consistent with this, activated IEL mediators protected cells against virus infection in vitro, and pre-activation of IEL in vivo profoundly limited norovirus infection. Hence, intraepithelial T cell activation offers an overt means to promote the innate antiviral potential of the intestinal epithelium.
Project description:The intestinal epithelium harbors large populations of activated and memory lymphocytes, yet these cells do not cause tissue damage in the steady state. We investigated how intestinal T cell effector differentiation is regulated upon migration to the intestinal epithelium. Using gene loss- and gain-of-function strategies, as well as reporter approaches, we showed that cooperation between the transcription factors T-bet and Runx3 resulted in suppression of conventional CD4(+) T helper functions and induction of an intraepithelial lymphocyte (IEL) program that included expression of IEL markers such as CD8?? homodimers. Interferon-? sensing and T-bet expression by CD4(+) T cells were both required for this program, which was distinct from conventional T helper differentiation but shared by other IEL populations, including TCR??(+)CD8??(+) IELs. We conclude that the gut environment provides cues for IEL maturation through the interplay between T-bet and Runx3, allowing tissue-specific adaptation of mature T lymphocytes.