Butyrate ameliorates DSS-induced ulcerative colitis in mice by facilitating autophagy in intestinal epithelial cells and modulating the gut microbiota through blocking the PI3K-AKT-mTOR pathway

BACKGROUND: Ulcerative colitis (UC) is an idiopathic, chronic inflammatory disease of the colon that imposes a significant global public health burden due to its recurrent and refractory nature. The therapeutic effects of butyrate on UC have been documented previously, but its specific mechanisms remain unclear. OBJECTIVE: This study aimed to investigate the effects and potential mechanisms of butyrate in dextran sulfate sodium (DSS)-induced UC. METHODS: A UC mouse model was induced utilizing 3% DSS, followed by interventions of 300 mg/kg, 600 mg/kg, or 1200 mg/kg of butyrate. The fecal condition and colonic pathology of the mice were observed, along with measurements of body weight and colon length. The expression of serum inflammatory factors, autophagy-related proteins, and the PI3K/AKT/mTOR pathway-related proteins were detected. Additionally, the impact of butyrate on the mouse gut microbial communities was evaluated using 16S rRNA sequencing technology. RESULTS: It was demonstrated that butyrate effectively alleviated UC symptoms, including bloody stools, weight loss, and colon shortening. Furthermore, butyrate reduced colonic tissue damage, decreased the expression of TNF-α, IL-1β, and IL-6, and significantly upregulated Beclin-1, Atg5, and the LC3II/I ratio, while reducing P62 expression. Butyrate also decreased the relative expression of p-PI3K/PI3K, p-Akt/Akt, and p-mTOR/mTOR. 16S rRNA sequencing results revealed that butyrate improved the intestinal microbial community structure by inhibiting harmful bacteria and accelerating the growth of beneficial bacteria. CONCLUSION: This study suggests that butyrate may alleviate DSS-induced UC in mice by blocking the PI3K/AKT/mTOR pathway to facilitating autophagy in intestinal epithelial cells and by modulating the gut microbiota.