Project description:HIV infection results in damage to the gastrointestinal (GI) tract, microbial translocation and immune activation, which are not completely ameliorated with suppression of viremia by antiretroviral (ARV) therapy. Furthermore, increased morbidity and mortality of ARV-treated HIV-infected individuals is associated with these dysfunctions. Thus, in order to enhance GI tract immunity, we treated SIV-infected pigtail macaques with ARVs supplemented with probiotics and prebiotics or with ARVs alone. In the colon, this synbiotic treatment resulted in increased expression of genes associated with antigen presenting cells (APCs), increased frequency and functionality of APCs, enhanced reconstitution and functionality of CD4+ T-cells and reduced fibrosis of lymphoid follicles. Thus, supplementing ARV treatment with synbiotic treatment in HIV-infected individuals may improve GI tract immunity and thereby mitigate inflammatory sequelae, ultimately improving prognosis. CD45+ (clone MB4-6D6) leukocytes were sorted from thawed colon samples from 4 ARV + probiotics animals and 4 ARV alone animals
Project description:HIV infection results in damage to the gastrointestinal (GI) tract, microbial translocation and immune activation, which are not completely ameliorated with suppression of viremia by antiretroviral (ARV) therapy. Furthermore, increased morbidity and mortality of ARV-treated HIV-infected individuals is associated with these dysfunctions. Thus, in order to enhance GI tract immunity, we treated SIV-infected pigtail macaques with ARVs supplemented with probiotics and prebiotics or with ARVs alone. In the colon, this synbiotic treatment resulted in increased expression of genes associated with antigen presenting cells (APCs), increased frequency and functionality of APCs, enhanced reconstitution and functionality of CD4+ T-cells and reduced fibrosis of lymphoid follicles. Thus, supplementing ARV treatment with synbiotic treatment in HIV-infected individuals may improve GI tract immunity and thereby mitigate inflammatory sequelae, ultimately improving prognosis.
Project description:Steroid-refractory gastrointestinal graft-versus-host disease (GI GVHD) is a major barrier to successful hematopoietic stem cell transplant (HSCT). Poor understanding of the pathophysiology of GI GVHD contributes to continued poor outcomes and high mortality rates. We therefore obtained rectosigmoidal mucosal biopsies from post-HSCT patients with GI GVHD and submitted them to RNA-sequencing in order to transcriptomally characterize GI GVHD. These were compared to patients undergoing endoscopy for routine clinical indications. Using single end, 50bp reads processed using Kallisto using genome annotations from Gencode v24 with transcripts per million as the output. We included 14,239 trancsripts in our analysis, where we compared GVHD vs non-GVHD with significance defined as FDR<0.05 and FC 1.5 using R package DESeq2. We identified 164 key genes, of which 141 were upregulated in GVHD, and were ontologically related to microbial response, key immune effectors, and cell migration/chemotaxis. Down-regulated genes were related to nutrient metabolism. Additionally, we performed WGCNA that highlighted ERK as a key upregulated pathway in GI GVHD.
Project description:Gastrointestinal (GI) tract involvement is a major determinant for subsequent morbidity and mortality arising during graft versus host disease (GVHD). CD4+ T cells that produce GM-CSF have emerged as central mediators of inflammation in this tissue site as GM-CSF serves as a critical cytokine link between the adaptive and innate arms of the immune system. However, cellular heterogeneity within the CD4+ GM-CSF+ T cell population due to the concurrent production of other inflammatory cytokines has raised questions as to whether these cells have a common ontology or if there exists a unique CD4+ GM-CSF+ subset that differs from other defined T helper (TH) subtypes. Using single cell RNA sequencing analysis, we identified two CD4+ GM-CSF+ T cell populations that arose during GVHD and were distinguishable by the presence or absence of IFN-γ co-expression. CD4+ GM-CSF+ IFN-γ- T cells which emerged preferentially in the colon had a distinct transcriptional profile, employed unique gene regulatory networks, and possessed a non-overlapping TCR repertoire when compared to CD4+ GM-CSF+ IFN-γ+ T cells as well as all other transcriptionally defined CD4+ T cell populations in the colon. Functionally, this CD4+ GM-CSF+ T cell population contributed to pathological damage in the GI tract which was critically dependent upon signaling through the IL-7 receptor but was independent of type 1 interferon signaling. Thus, these studies help to unravel heterogeneity within CD4+ GM-CSF+ T cells that arise during GVHD and define a developmentally distinct colitogenic TH GM-CSF+ subset that mediates immunopathology.
Project description:Using an experimental model of graft versus host disease (GVHD) to examine T cell-mediated inflammation within the colon, we identified a unique CD4+ T cell population that constitutively expresses the β2 integrin, CD11c, has a biased central memory phenotype and memory T cell transcriptional profile, possesses innate-like properties by gene expression analysis, and has increased expression of the gut-homing molecules, α4β7 and CCR9. Using a number of complementary GVHD mouse models, we show that adoptive transfer of these cells results in TH1-mediated proinflammatory cytokine production, augmented pathological damage in the colon, and increased mortality due to early accumulation of these cells in the GI tract. The pathogenic effects of this CD4+ T cell population was critically dependent upon co-expression of the IL-23 receptor which was required for maximal inflammatory effects. Colonic inflammation was regulated by IL-10 that was produced by non-Foxp3-expressing CD4+ T cells which attenuated lethality in the absence of functional CD4+ Foxp3+ T cells. Thus, coordinate expression of CD11c and the IL-23R defines a novel IL-10 regulated, colitogenic memory CD4+ T cell subset that is poised to initiate inflammation when there is loss of tolerance and breakdown of mucosal barriers as occurs in GVHD as well as other immune-mediated inflammatory bowel disorders.
Project description:Host NLRP6 regulates innate immune responses and gastrointestinal (GI) homeostasis. It plays a protective role in pathogenic processes such as intestinal colitis and tumorigenesis in a microbiome dependent manner. Host innate immunity and changes in microbial diversity also play a role in the severity of allo-immune-mediated gastrointestinal pathogenic process, namely graft-versus-host disease (GVHD), the principal toxicity after allogeneic bone marrow transplantation (allo-BMT). Herein, we examined the role of NLRP6 in multiple murine models of allo-BMT. In contrast to its role in intestinal colitis, host NLRP6 aggravated GI GVHD. NLRP6-deficient animals showed improved intestinal barrier function, increased levels of tissue repair associated proteins and preserved Goblet and Paneth cell numbers in the GI tract after allo-BMT. The impact of host NLRP6 deficiency in mitigating GVHD was observed regardless of co-housing, antibiotic treatment, or colonizing littermate germ free wild type (WT) and NLRP6 deficient hosts with fecal microbial transplantation from SPF WT and Nlrp6-/- animals. Chimera studies were performed to assess the role of NLRP6 expression on host hematopoietic and non-hematopoietic cells. The allogeneic [B6Ly5.2→Nlrp6-/-] animals demonstrated significantly improved survival compared to the allogeneic [B6Ly5.2→B6] animals, demonstrating that the absence of NLRP6 in host non-hematopoietic cells is crucial for the protection against GVHD, but did not alter the therapeutic graft-versus-tumor effects after BMT. Our results unveil a novel role for NLRP6 and demonstrate a pathogenic role in GVHD that is independent of variations in its intestinal microbiome in contrast to its well-appreciated microbiome-dependent protective role in intestinal colitis and tumorigenesis.
Project description:We demonstrate a unique gene signature in acute GI GVHD with differential expression of genes which have been previously described as important in GVHD
Project description:Alloimmune T cell mediated gastrointestinal graft-versus-host disease (GI-GVHD) occur after bone marrow translantation (BMT). GI-GVHD cause significant morbidity and mortality. Immunosuppression therapies have shown good results with adverse effects, but are still incomplete. The biology of GVHD are often understood from the immune cell perspectve, but the pathogenesis and severity from host IEC traget cell perspective remain undefined. We used next generation sequencing transcriptome to detail the gene expression of colonic epithelial cells underlying the profile changes between the syngeneic recipient and allogeneic recipient.
Project description:The epithelial layer of the gastrointestinal tract is the body’s first line of defense against gut pathogens. However, our current understanding of the innate immune response of the epithelial layer is limited. For this study, we used gastrointestinal organoids which have the advantage of being primary, non-transformed epithelium that retains organ-specific characteristics in culture, and also that they lack any confounding immune cells. We systematically profiled the transcriptomes of gastrointestinal epithelial cells using a newly generated biobank of human and murine GI organoids grown from tissue-resident stem cells, providing an atlas of gene expression along the GI tract of both species. RNA sequencing of all lines confirmed the preservation of tissue identity, and in addition revealed extensive organization of innate immune signaling components along the cephalocaudal axis, endowing a specific innate immune profile to each segment.
Project description:SARS-CoV-2 infects epithelial cells of the human gastrointestinal (GI) tract and causes related symptoms. HIV infection impairs gut homeostasis and is associated with an increased risk of COVID-19 fatality. To investigate the potential link between these observations, we analyzed single-cell transcriptional profiles and SARS-CoV-2 entry receptor expression across lymphoid and mucosal human tissue from chronically HIV-infected individuals and uninfected controls. Absorptive gut enterocytes displayed the highest coexpression of SARS-CoV-2 receptors ACE2, TMPRSS2, and TMPRSS4, of which ACE2 expression was associated with canonical interferon response and antiviral genes. Chronic treated HIV infection was associated with a clear antiviral response in gut enterocytes and, unexpectedly, with a substantial reduction of ACE2 and TMPRSS2 target cells. Gut tissue from SARS-CoV-2–infected individuals, however, showed abundant SARS-CoV-2 nucleocapsid protein in both the large and small intestine, including an HIV-coinfected individual. Thus, upregulation of antiviral response genes and downregulation of ACE2 and TMPRSS2 in the GI tract of HIV-infected individuals does not prevent SARS-CoV-2 infection in this compartment. The impact of these HIV-associated intestinal mucosal changes on SARS-CoV-2 infection dynamics, disease severity, and vaccine responses remains unclear and requires further investigation.