Gut Microbiota Alter Visceral Pain Sensation and Inflammation via Modulation of Synthesis of Resolvin D1 in Colonic Tuft Cells.

Abstract

Background and AimsVisceral hypersensitivity and low grade mucosal inflammation are frequently observed in a subpopulation of irritable bowel syndrome (IBS) patients. The responsible mechanism is unclear. Resolvins are a novel class of anti-inflammatory lipid mediators that regulate resolution of inflammation and pain. We hypothesize that resolvin D1 (RvD1) synthesis is reduced in IBS-D colonic mucosa and contribute to the development of visceral hypersensitivity. MethodsWe used ELISA and qPCR to quantify the levels of RvD1 synthesis and the gene expression of LOX5 and LOX12 in colonic biopsy samples from healthy individuals (HC) or IBS-D patients. To evaluate the role of gut bacteria in regulating RvD1 synthesis, we colonized germ-free mice with different strains of bacteria, fecal microbiota from HC individuals or IBS-D patients. To evaluate the role of tuft cells in RvD1 synthesis, we examined the effect of fecal supernatant of IBS-D or HC subjects on human colonoids as well as colonoids from mice in which Chat-cre recombinase vector was used to knock-in diphtheria toxin sensitive receptor (DTRf/f) or knock-out the expression of Tlr4f/f or MyD88f/f. ResultsWe report that colonic biopsy samples from IBS-D patients generated significantly lower level of RvD1 and LOX5 mRNA. The conventionalization of germ-free mice with microbiota from IBS-D patients or gram-negative bacteria inhibited RvD1 biosynthesis and caused visceral hypersensitivity and mucosal inflammation. Colonic organoid studies demonstrate that Lps downregulated Lox5 mRNA expression and synthesis of RvD1 via Tlr4-MyD88 receptor signaling pathway in colonic tuft cells. ConclusionsOur findings indicate that RvD1 is generated in colonic tuft cells to regulate gut sensitivity to mechanical stimulation. Colonic commensal bacterial composition regulates the synthesis of RvD1 in colonic mucosa which is reduced in IBS-D patients. This appears to be mediated by elevated fecal lipopolysaccharide secondary to gram-negative gut dysbiosis.