Role of GBP5 in NLRP3 inflammasome mediated intestinal inflammation in Crohn’s disease

NLRP3 inflammasome is implicated in the pathogenesis of inflammatory bowel diseases (IBD). Since guanylate binding protein 5 (GBP5) induces the NLRP3 inflammasome activity, we aim to investigate the potential role of GBP5 in IBD pathogenesis.The expression of GBP5, NLRP3 inflammasome and related cytokines and chemokines were examined in two cohorts of IBD patients and healthy controls, by microarray transcriptome analysis, quantitative real time PCR, Western blot and Luminex Multi-Analyte Profiling technology. Cellular and subcellular localization of GBP5 in colonic biopsies were examined by immunohistochemistry and immunofluorescence with confocal microscopy. For functional studies, GBP5 expression was induced by IFNγ or silenced by siRNA or CRISPR/CAS9 technique.Expression of GBP5 was elevated in colonic mucosa in two geographically and culturally distinct IBD cohorts. In colonic tissues of IBD patients, the expression of GBP5 was mainly confined to immune cells and the levels of GBP5 expression were correlated with those of the inflammatory cytokines and chemokines. In cultured T and macrophage cells, expression of proinflammatory cytokines and chemokines were increased when GBP5 was induced, while GBP5 deficiency leads to decreased expression of the proinflammatory mediators including gasdermin D, caspase 1 and pro-IL1β.GBP5 is required in the expression of many inflammatory cytokines and chemokines in intestinal immune cells. In addition, GBP5 may up-regulate inflammatory reactions through an inflammasome mediated mechanism. Highly elevated GBP5 expression at the inflamed colonic mucosa in two geographically and culturally distinct IBD cohorts indicates that GBP5 plays a common and important role in IBD pathogenesis, and therefore, is a potential therapeutic target for the management of IBD patients of various genetic and environmental backgrounds.