Irisin attenuates inflammation in a mouse model of ulcerative colitis by altering the intestinal microbiota

Evidence has demonstrated that the gut microbiota, which consists of probiotics and pathogenic microorganisms, is involved in the initiation of ulcerative colitis (UC) via the dysregulation of intestinal microflora and normal immune interactions, which ultimately leads to intestinal mucosal dysfunction. Irisin is released from muscle cells and displays anti-inflammatory effects; however, the mechanisms underlying irisin-mediated anti-inflammatory effects in UC have not been previously reported. In the present study, mice were divided into the following four groups: i) Control; ii) irisin; iii) dextran sulfate sodium (DSS) salt; and iv) DSS + irisin. Subsequently, the effects of irisin were investigated by observing alterations in intestinal microbes. Irisin significantly reduced the degree of inflammation in UC by reversing alterations to the macroscopic score, histological score, number of CD64⁺ cells and inflammatory cytokine alterations (P<0.05). Analysis of the microbial diversity in the stools of mice with active UC indicated that the five bacteria that displayed the greatest alterations in relative abundance were Alloprevotella, Bacteroides, Lachnospiraceae-UCG-001, Prebotellaceae-UCG-001 and Rikenellaceae-RCB-gut-group. Furthermore, Bactoroides were positively correlated with the histopathological score (P=0.001; R=0.977) and interleukin (IL)-23 levels (P=0.008; R=0.924). Alloprevotella (P=0.001; R=-0.943), Lachnospiraceae-UCG-001 (P=0.000; R=-0.973) and Rikenollaceae-RC8-gut-group (P=0.001; R=-0.971) were negatively correlated with the histopathological score. Furthermore, Lachnospiraceae-UCG-001 (P=0.01; R=-0.873) and Rikenollaceae-RC8-gut-group (P=0.049; R=-0.814) were negatively correlated with IL-23 levels. In summary, the results of the present study suggested that irisin improved inflammation in a UC mouse model potentially via altering the gut microbiota.