Regulatory effects of Ophiopogon japonicus polysaccharide on intestinal immune function in mice

We investigated the potential immunomodulatory effects of Ophiopogon japonicus polysaccharide (OJP), extracted from the functional edible plant, Ophiopogon japonicus. We characterized the functional groups of OJP and monosaccharide composition, and evaluated its effects on intestinal immunity in healthy and Cyclophosphamide (CTX)-induced immunosuppressed mice. Oral administration of OJP enhanced the levels of intestinal secretory immunoglobulin A (sIgA) and the proportion of IgA⁺ cells, activated immune cells in mesenteric lymph nodes (MLNs) and Peyer's patches (PPs), upregulated immune-related gene expression, and improved gut microbial composition in healthy mice. OJP partially restored body weight and blood indices, promoted secretion of immune-related cytokines, enhanced lymph node immune cell activity, increased plasma cell numbers, and upregulated immune gene expression in immunocompromised mice. Furthermore, OJP promoted the expression of tight junction proteins and improved both microbial diversity and richness in the gut. These findings suggest that OJP effectively enhances intestinal immunity and supports gut homeostasis, offering a promising strategy for the development of immune-enhancing agents in clinical applications.