Role of metabolites derived from gut microbiota in inflammatory bowel disease

Abstract

Over the past two decades, it is improved gut microbiota plays an important role in the health and disease pathogenesis. Metabolites, small molecules produced as intermediate or end products of microbial metabolism, is considered as one of the major interaction way for gut microbiota with the host. Bacterial metabolisms of dietary substrates, modification of host molecules or bacteria are the major source of metabolites. Signals from microbial metabolites affect immune maturation and homeostasis, host energy metabolism as well as mucosal integrity maintenance. Based on many researches, the composition and function of the microbiota can be changed, which is also seen in the metabolite profiles of patients with inflammatory bowel disease (IBD). Additionally, some specific classes of metabolites also can trigger IBD. In this paper, definition of the key classes of microbial-derived metabolites which are changed in IBD, description of the pathophysiological basis of association and identification of the precision therapeutic modulation in the future are the major contents.

Keywords: Inflammatory bowel disease; Microbial metabolites; Short chain fatty acids; Bile acids; Tryptophan

Core Tip: In the gastrointestinal tract of the human, a variety of microorganisms such as bacteria, fungi, viruses, archaea and protozoa are collected and considered as a community, containing a genome, suitable to the environment and the host. Microbiome, with wide functions, can ferment dietary fibres, defence pathogen, synthesize vitamin and promote immune maturation and metabolic homeostasis, which indicates microbiome is deeply integrated with human biology. However, because gut microbiota is associated with ancestral diet high in fibre, the dietary alteration resulted from western diet causes maladaptive change for this association, and products of microbial metabolism exist at a nexus between host and microbiome.