Rice hull insoluble dietary fiber alleviated experimental colitis induced by low dose of dextran sulfate sodium in cadmium-exposed mice

Cadmium (Cd), an important toxic environmental pollutant, can invade the gastrointestinal tract and induce the occurrence of gastrointestinal diseases. This study aimed to investigate the protective effect of rice hull insoluble dietary fiber (RHF) on Cd-promoted colitis induced by low dose of dextran sulfate sodium. Administration of RHF attenuated inflammation by limiting Cd accumulation and regulating intestinal immune homeostasis in colitis mice with Cd exposure. RHF could maintain the structure of the gut barrier by increasing mucin secretion and intestinal tight connectivity in mice. Subsequently, RHF repressed the colonic inflammation mediated by the TLR4/MyD88/NF-κB pathway, and inhibited the transcription regulation of inflammatory cytokines. Furthermore, RHF showed an enhancement of a variety of probiotics, such as Eubacterium and Faecalibaculum. RHF also inhibited the growth of pathogenic bacteria, including Erysipelatoclostridium, Helicobacter and Bacteroides. The growth of beneficial bacteria was also accompanied by reversing the decline in short-chain fatty acids, supporting the initial potentiality of RHF as a prebiotic in cases of damage by Cd exposure in colitis mice. Importantly, RHF also remained resistant to Cd toxicity in colitis mice when the gut microbiota was depleted by antibiotics. We suggest that RHF could be used as a novel dietary supplement strategy against Cd-exacerbated colitis.