Diet prevents the expansion of segmented filamentous bacteria and ileo-colonic inflammation in a model of Crohn’s disease

Abstract

ABSTRACTCrohn’s disease (CD) is associated with changes in the microbiota, and murine models of CD-like ileo-colonic inflammation depend on the presence of microbial triggers. Increased abundance of unknown Clostridiales and the microscopic detection of filamentous structures close to the epithelium of TnfΔARE mice pointed towards segmented filamentous bacteria (SFB), a commensal well-known to induce the maturation of Th17 cell-derived immune responses that is highly implicated in the pathogenesis of IBD. We show that the abundance of SFB strongly correlates with the severity of CD-like ileal inflammation in TnfΔARE and SAMP/Yit mice. SFB mono-colonization of germ-free TnfΔARE mice confirmed the causal link and resulted in severe ileo-colonic inflammation, characterized by elevated tissue levels of Tnf and Il-17, neutrophil infiltration and loss of Paneth and goblet cell function. Co-colonization of SFB in human-microbiota associated TnfΔARE mice confirmed that SFB presence is indispensable for disease development. Screening of 412 ileal and colonic mucosal biopsies from IBD patients using previously published and newly designed human SFB-specific primer sets showed no presence of SFB in human tissue samples. Simulating the protective effect of exclusive enteral nutrition (EEN) by feeding SFB mono-colonized TnfΔARE mice EEN-like purified diet antagonized SFB colonization and prevented disease development in TnfΔARE mice, clearly demonstrating the important role of diet in modulating this IBD-related but murine pathobiont.