Fermented rice bran supplementation attenuates colonic injury through modulating intestinal aryl hydrocarbon receptor and innate lymphoid cells in mice with dextran sodium sulfate-induced acute colitis

This study investigated the effects of fermented rice bran (FRB) on modulating intestinal aryl hydrocarbon receptor (AhR) expression, innate lymphoid cell (ILC)3 populations, the fecal microbiota distribution, and their associations with dextran sodium sulfate (DSS)-induced acute colitis. C57BL/6 mice were assigned to four groups: 1) NC group, normal mice fed the AIN-93M diet; 2) FRB group, normal mice fed a diet supplemented with 5% FRB; 3) NCD group, DSS-treated mice fed AIN-93M; 4) FRBD group, DSS-treated mice fed a 5% FRB-supplemented diet. DSS was administered for 5 d and followed by 5 d for recovery. At the end of the experiment, mice were sacrificed. Their blood and intestinal tissues were collected. Results showed that there were no differences in colonic biological parameters and function between the NC and FRB groups. Similar fecal microbiota diversity was noted between these two groups. Compared to the non-DSS-treated groups, DSS administration led to increased intestinal permeability, enhanced inflammatory cytokine production and disease severity, whereas tight junctions and AhR, interleukin (IL)-22 expressions were downregulated, and the ILC3 population had decreased. Also, gut microbiota diversity differs from the non-DSS-treated groups and more detrimental bacterial populations exist when compared to the FRBD group. FRB supplementation in DSS-treated mice attenuated fecal microbial dysbiosis, decreased intestinal permeability, improved the barrier integrity, upregulated AhR and IL-22 expression, maintained the ILC3 population, and pathologically mitigated colonic injury. These findings suggest enhanced ILC3- and AhR-mediated functions may be partly responsible for the anti-colitis effects of FRB supplementation in DSS-induced colitis.