Immune Enhancement of Fermented Ruditapes philippinarum Polysaccharide on Immunosuppressed BALB/c Mice Induced by Cyclophosphamide

Polysaccharides from marine organisms have been extensively studied and utilized as functional food ingredients due to their excellent immunomodulatory properties. However, the immunomodulatory potential of fermented <i>Ruditapes philippinarum</i> polysaccharide (RPP) has not been systematically explored. This study investigated the effects of RPP on immune function in cyclophosphamide (CTX)-induced immunosuppressed <i>BALB/c</i> mice. These results revealed that RPP alleviated CTX-induced weight loss and restored appetite. Moreover, RPP can promote the morphology and indices of immune organs, as well as increased the number of white blood cells (WBC), red blood cells (RBC), and hemoglobin (Hb). Serum levels of interleukin-6 (IL-6) and immunoglobulin E (IgE) were significantly elevated following RPP treatment. Additionally, RPP improved colonic morphology by upregulating the expression of E-cadherin and ZO-1 and promoting the secretion of secretory IgA (sIgA). These results indicated that RPP exerted an immune protective effect in <i>BALB/c</i> mice and justified its further potential as a bioactive ingredient for functional foods derived from marine shellfish.