A dietary sulfated polysaccharide from edible green alga Caulerpa chemnitzia modulates immune responses associated with host metabolism and gut microbiota in cyclophosphamide-induced immunosuppressed mice.

Sulfated polysaccharides from edible marine algae have attracted increasing interest as dietary components with immune-supporting potential. Caulerpa chemnitzia, an edible green alga widely distributed in Indo-Pacific regions, has long been consumed fresh as a vegetable and is rich in sulfated polysaccharides. In our previous study, a sulfated polysaccharide fraction (CRVP) isolated from the edible green alga Caulerpa chemnitzia was structurally characterized and shown to regulate macrophage immune responses in vitro. However, its in vivo immunomodulatory effects and functional relevance as a food-derived polysaccharide remain unclear. In the present study, the immune-supporting potential of CRVP was evaluated in a cyclophosphamide-induced immunosuppressed mouse model. CRVP supplementation improved peripheral blood immune cell profiles, enhanced plasma cytokine levels, and restored bone marrow cell numbers and macrophage differentiation capacity, indicating that CRVP may mitigate CTX-induced immune-related changes. These effects may be associated with increased succinate levels and the potential involvement of HIF-1α/IL-1β-related inflammatory signaling, as suggested by LW6 intervention. In addition, 16S rDNA sequencing revealed that CRVP modulated gut microbiota composition, with potential involvement of Alistipes, Lachnoclostridium, and members of Erysipelatoclostridiaceae. Furthermore, fecal metabolomic analysis indicated concurrent alterations in metabolic profiles, particularly in tryptophan metabolism. Overall, this study provides in vivo evidence that CRVP, a dietary sulfated polysaccharide from an edible green alga, exerts immune-supporting effects through metabolic and microbiota-associated pathways, thereby providing a basis for its potential application as an immune-supporting functional food ingredient.