Probiotic-fermented Chinese dwarf cherry [Cerasus humilis (Bge.) Sok.] juice modulates the intestinal mucosal barrier and increases the abundance of Akkermansia in the gut in association with polyphenols

Polyphenols have long been used as functional compounds and are beneficial for host immunity and gut health. This three-phased study investigated the function of Ouli fermented juice (OF) in improving the immunity of cyclophosphamide (CTX)-immunosuppressed mice and regulating their intestinal microbiota and mucosal barrier. Lactobacillus plantarum fermentation increased the phenolic content in the OF. OF effectively improved host immunity and the intestinal mucosal barrier, including increasing serum immunoglobulin (Ig)A, IgG, and IgM levels and secreted IgA (sIgA) levels in the colon, and reduced CTX-induced pathological damage to the spleen and jejunum. Importantly, OF effectively increased the abundance of Lachnospiracea, Roseburia, Akkermansia, and butyric acid-producing microbes, subsequently increasing the levels of short chain fatty acids in the colon. OF with polyphenols exhibited better efficacy at altering the intestinal flora, which might affect the host immunity by changing the host-mucosal barrier-microbiota interaction.