Mannatide modulates immune response and gut microbiota in cyclophosphamide-induced immunosuppressed BALB/c mice.

Mannatide, a polysaccharide-based immunomodulator, has been widely used in China to enhance immune function, yet its mechanisms remain underexplored. This study investigated the immunoprotective effects of Mannatide in cyclophosphamide (CTX)-induced immunosuppressed mice, focusing on modulation of the gut microbiota and associated signalling pathways. Results demonstrated that Mannatide restored immune organ indices (spleen and thymus), elevated serum cytokines (IL-2, IFN-γ, TNF-α), improved the CD4+/CD8+ ratio, and upregulated intestinal tight junction proteins (Claudin1, Occludin1, ZO-1). Additionally, Mannatide also attenuated CTX-induced phosphorylation of p38 and JNK and shifted apoptosis-related markers toward a protective profile, as indicated by reduced Bax and increased Bcl-2 expression in splenocytes. Furthermore, increased intestinal TLR4 and p65 mRNA suggests recovery of innate immune signalling rather than a simple anti-inflammatory effect. Gut microbiota analysis revealed a restored Bacteroidetes/Firmicutes ratio and enriched SCFA-producing genera (Parabacteroides, Clostridia-UCG-014), correlating with increased faecal SCFAs (acetate, butyrate). Together, these findings highlight that Mannatide is associated with immune recovery in CTX-treated mice, accompanied by changes in gut microbiota, SCFA production, and immune-related signalling pathways, and provide insights for adjuvant therapies targeting the gut-immune axis.