Rape bee pollen alleviates dextran sulfate sodium (DSS)-induced colitis by neutralizing IL-1β and regulating the gut microbiota in mice

Abstract Colitis is a major chronic disease in today's society. Consumption of phenolic compounds can protect against colitis. We examined the phenolic compounds of rape bee pollen extract (RPE) and investigated its prevention of DSS-induced colitis in C57BL/6 mice. HPLC-DAD-ECD analysis showed that 7 phenolic compounds were tentatively identified in RPE, of which kaempferol had the highest content (19.87 mg/g), followed by sinapic acid and rosmarinic acid. RPE at 21.2 g/kg BW (HD – high-dose group) and 10.6 g/kg BW (LD – low-dose group) ameliorated colon shortening, spleen swelling and colon weight reduction, improved the structure of colonic villi, glandular structures and crypts, which was further confirmed by conventional histological assessment, and inhibited the activities of related inflammatory cytokines. In particular, IL-1β expression was downregulated by approximately 90% compared with that of the model group. Additionally, treatment with RPE altered the gut microbial structure of mice with colitis, showing that the abundances of Allobaculum and Bacteroides were significantly reduced and the abundance of Lactobacillus was markedly increased. This study indicated that RPE could protect the colon from DSS-induced colitis by increasing antioxidant capacity, alleviating inflammation and regulating the gut microbiota. This paper was conducted to investigate the potent protective effects of RPE treatments on a mouse model of colitis and provided new ideas for the application of rape bee pollen.