Int J Biol Macromol 2025 Apr 16;301:139929. doi: 10.1016/j.ijbiomac.2025.139929.

Fucoidan from Apostichopus japonicus enhances intestinal barrier function and promotes intestinal immunity via regulating the gut microbiota and tryptophan metabolism.

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Apostichopus japonicus is one of the most popular types of sea cucumber among consumers in Southeast Asia. Fucoidan from Apostichopus japonicus (Aj-FUC) has attracted considerable attention because of its immunomodulatory activities. Aj-FUC is indigestible in the human upper gastrointestinal tract but can be utilized by the gut microbiota. Thus, we suspect that Aj-FUC interacts with the gut to enhance immunefunction. This study showed that after a three-week intervention with Aj-FUC (100 mg/kg/d), the gut microbiota in mice developed a new homeostasis. Subsequently, in the condition of intestinal flora homeostasis, the effects of Aj-FUC on intestinal health in normal mice and the prevention of intestinal mucosal damage in cyclophosphamide-induced mice were investigated. Aj-FUC preserved intestinal structural integrity, increased the number of goblet cells, upregulated the expression of ZO-1 and Occludin, stimulated the secretion of sIgA and IgA, and maintained the Th1/Th2 balance. Importantly, beneficial bacteria were enriched, and tryptophan metabolism-related metabolites such as 5-hydroxyindole-3-acetic acid, and indole-3-lactic acid were upregulated following Aj-FUC administration. In summary, a three-week Aj-FUC intervention could result in the formation of a new homeostasis in intestinal flora, while the effect of Aj-FUC on intestinal immunity was related to the regulation of tryptophan metabolism by gut microbiota.

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