Elemental diet enriched in amino acids alters gut microbial community and prevents colonic mucus degradation in mice with colitis

Abstract

AbstractThe role of dietary amino acids or intact proteins in the progression of colitis remains controversial, and the mechanism involving gut microbes is unclear. Here, we investigated the effects of an elemental diet (ED) enriched in amino acids and a polymeric diet enriched in intact protein on the pathogenesis of DSS-induced colitis in mice. Our results showed that ED induced remission of colitis in mice. Notably, ED treatment reduced the abundance of the mucolytic bacteria Akkermansia and Bacteroides, which was attributed to the decreased colonic protein fermentation. Consistently, the activities of mucolytic enzymes were decreased, leading to the protection of mucus layer degradation and microbial invasion. The fecal microbiota transplantation of ED-fed mice reshaped microbial ecology and alleviated intestinal inflammation in recipient mice. ED failed to induce remission of colitis in pseudo-germ-free mice. Together, we convincingly demonstrated the critical role of gut microbiota in the prevention of ED on colitis.ImportanceThe prevalence of inflammatory bowel disease is rapidly increasing and has become a global burden. Several specific amino acids have been shown to benefit mucosal healing and colitis remission. However, the role of amino acids or intact proteins in diets and enteral nutrition formulas is controversial, and the mechanisms involving gut microbes remain unclear. In this study, we investigated the effects of an elemental diet (ED) enriched in amino acids and a polymeric diet enriched in intact protein on the pathogenesis of colitis in mice. The underlying mechanisms were explored by utilizing fecal microbiota transplantation and pseudo-germ-free mice. ED treatment reduced the abundance of mucolytic bacteria, thereby protecting the mucus layer from microbial invasion and degradation. For the first time, we convincingly demonstrated the critical role of gut microbiota in the effects of ED. This study may provide new insights into the gut microbiota-diet interaction in human health.