A comprehensive review of mucilage polysaccharides with dual immunomodulatory and anti-tumor activities: Mechanisms, structure-activity relationships and application prospects in tumor immunotherapy

Mucilage polysaccharides (MPs) are natural biopolymers with strong biocompatibility and promising dual immunomodulatory and anti-tumor activities. This review summarizes current evidence on the molecular mechanisms, structure-activity relationships, and potential applications of MPs in tumor immunotherapy. Evidence shows that MPs can directly suppress tumor growth by inducing apoptosis, arresting the cell cycle, and inhibiting proliferation, migration, and angiogenesis. They also exert indirect anti-tumor effects by activating macrophages and lymphocytes, regulating cytokine production, and remodeling the immunosuppressive tumor microenvironment, mainly through TLR-mediated NF-κB and MAPK signaling pathways. Their biological functions are closely linked to structural features, including molecular weight, monosaccharide composition, glycosidic linkages, and sulfation or acetylation modifications. By integrating findings from multiple sources, this review identifies key structural determinants underlying the dual immunomodulatory and anti-tumor activities of MPs. The novelty of this review lies in providing a comprehensive analysis of MPs from different sources, linking structural features with biological activities and therapeutic applications, a topic that has not been systematically addressed in previous reviews. Overall, MPs are promising candidates for cancer intervention and carbohydrate-based immunotherapy. However, current studies remain largely limited to source-specific investigations and fragmented mechanistic evidence. Future studies should emphasize precise structural characterization, mechanistic validation, and structure-guided application in tumor immunotherapy.