Si–Ni-San improves experimental colitis by favoring Akkermensia colonization

Ulcerative colitis (UC) is widely believed to be a leading risk factor of colorectal cancer. Gut microbiota is a known vital player in the progression of UC. Si-Ni-San (SNS) has been considered to effectively treat colitis in clinical practice during thousands of years, yet whether SNS ameliorated acute colitis mouse model by modulating intestinal flora has not been distinctly elucidated.Our study aimed to elucidate the effect of SNS against acute murine colitis and focused on the underlying mechanisms of SNS targeting gut microbiota.16S RNA sequencing, molecular biological analysis, and fecal microbiota transplants (FMT) were conducted to reveal the mechanisms of SNS in regulating gut microbiota.In our study, SNS dramatically inhibited DSS-induced acute inflammatory responses by improving gut microbiota dysbiosis, as evidenced by decreased abundance proinflammatory species, upregulated abundance of anti-inflammatory species and potentially altered microbiota metabolite metabolism. Additionally, intestinal flora knockout and FMT experiments confirmed that the therapeutic effect of SNS on colitis was dependent on gut microbiota, and specifically on favoring the growth of potential probiotics, Akkermansia genus. Furthermore, we found that SNS alone and SNS combined with Akkermansia muciniphila (A. muciniphila) increased Mucin 2 (MUC2) production, thus enhancing the competitive edge of A. muciniphila among pathogenic gut microbiota.Our study shed lights on the underlying mechanism of SNS in attenuating acute murine colitis from the perspective of intestinal flora and provides novel insights into the discovery of adjacent therapeutic strategy against colitis based on SNS and probiotics.Gastro-intestinal system.