Clitocybe squamulosa Polysaccharides Ameliorate Dextran Sulfate Sodium‐Induced Colitis by Regulating the PI3K/AKt/mTOR Pathway and the Intestinal Flora in Mice

ABSTRACT Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by persistent inflammation and ulceration of the colon. This research investigated the protective effects of Clitocybe squamulosa fruiting body polysaccharide (CSFP) and purified polysaccharides named CE on dextran sulfate sodium (DSS)‐induced UC in mice. CSFP and CE significantly alleviated clinical symptoms and histopathological damage, enhanced the activity of antioxidant enzymes (catalase [CAT], superoxide dismutase [SOD], and glutathione peroxidase [GSH‐Px]), and regulated inflammatory markers (TNF‐α, IL‐6, IL‐1β, and IL‐10). Importantly, both polysaccharides reinforced intestinal barrier integrity by upregulating tight junction proteins (ZO‐1, occludin, claudin‐1) and mucins (MUC2/3). Mechanistically, CSFP and CE enhanced the expression of autophagy‐related proteins Beclin1, autophagy‐related gene‐5/7 (Atg5/7), and LC3‐II, while reducing the accumulation of p62. Further studies confirmed that CSFP and CE may be novel targets for alleviating DSS‐induced colitis through the inhibition of PI3K/Akt/mTOR pathway. In parallel, CSFP and CE remodeled gut microbiota composition, enriching beneficial bacteria such as Akkermansiaceae, Muribaculaceae, Bifidobacteriaceae, and Dubosiella , while suppressing harmful Lachnospiraceae. These microbial shifts promoted short‐chain fatty acid (SCFA) production and upregulated SCFA receptors (GPR41/43/109A), further contributing to intestinal homeostasis. These results indicate that CSFP and CE can improve colitis by regulating autophagy and modulating the gut microbiota, thus exerting a protective effect against DSS‐induced colitis, and providing a promising basis for their development as functional food ingredients or nutraceuticals for intestinal health.