Low dietary fiber intake impairs small intestinal Th17 and intraepithelial T cell development over generations

Abstract

Dietary fiber strongly impacts the microbiota. Here, we show that a low-fiber diet changes the small intestinal (SI) microbiota and impairs SI Th17, TCRαβ+CD8αβ+ and TCRαβ+CD8αα+ intraepithelial Tcell development. We restore Tcell development with dietary fiber supplementation, but this defect becomes persistent over generations with constant low-fiber diets. Offspring of low-fiber diet-fed mice have reduced SI Tcells even after receiving a fiber-rich diet due to loss of bacteria important for Tcell development. In these mice, only a microbiota transplant from a fiber-rich diet-fed mouse and a fiber-rich diet can restore Tcell development. Low-fiber diets reduce segmented filamentous bacteria (SFB) abundance, impairing its vertical transmission. SFB colonization and a fiber-rich diet partially restore Tcell development. Finally, we observe that low-fiber diet-induced Tcell defects render mice more susceptible to Citrobacter rodentium infection. Together, these results demonstrate the importance of fiber to microbiota vertical transmission and host immune system development.