Microbiota, Tertiary Lymphoid Structures and Chronic Inflammation in the Human Gut

项目总结

PROJECT SUMMARY Tertiary lymphoid structures (TLS) are ectopic disorganized lymphoid aggregates with the cellular composition resembling secondary lymphoid organs. Although the exact function of TLS remains elusive, the accumulated evidence suggests that TLS significantly contribute to the pathogenesis of chronic disorders including autoimmune and inflammatory diseases, graft versus host disease, transplant rejection, and various types of cancer. Therefore, better understanding of the composition of TLS and specificity of the immune response that they initiate in the context of a specific disease may help decode the disease pathogenesis and provide novel therapeutic strategies. Inflammatory bowel disease (IBD), which includes Crohn’s disease (CD) and ulcerative colitis (UC), is thought to result from the dysregulated immune response to commensal microbes driven by a convergence of genetic, environmental and microbial factors. Studies in humans and animal models indicate that IBD pathogenesis is associated with dysregulated mononuclear phagocyte (MP) system and abnormal T and B cell responses. We recently identified the mechanisms that drive TLS development in mice with Salmonella colitis. In this new study we will take advantage of our expertise, established collaboration and clinical resources available at UMass Medical School (UMMS) to understand the mechanisms that drive TLS development and function in human IBD. Our overarching hypothesis is that TLS in IBD are dysregulated towards a preferential generation of local proinflammatory IgG response instead of IgA and are induced by specific inflammatory MP subsets in response to pathobionts that colonize the mucosa. To test the hypothesis, we are going to analyze intestinal surgical resections from patients with IBD by applying a combination of multi-OMICs approaches. Our actively collaborating multi-disciplinary team that consists of experts in MP biology, computational biomedicine, bacterial microbiome, virome, gastroenterology and clinical GI pathology is uniquely positioned to address the following specific aims: Aim 1. Establish cellular composition and predict intercellular interactions in TLS in human IBD; Aim 2. Identify pathobionts that drive TLS formation via MP activation in human IBD. As the outcome of this project, we will establish a model of cell-cell and cell-microbe interactions and identify key regulatory molecules required for development of intestinal TLS in human IBD. Short term, these results will provide a basis for our future R01 proposal that will test computational predictions of host-microbial interactions and link them to disease pathogenesis with the underlying rationale to identify novel therapeutic avenues aimed at TLS in IBD. In the long term, information and methodology gained from this study will be applied to other inflammatory and autoimmune conditions as well as cancers in which TLS formation is evident.