Effects of Ginkgo Biloba Leaf Polysaccharides on Immune Function in Immunosuppressed Mice

Ginkgo biloba leaf polysaccharides (GBLP) are bioactive compounds with immunomodulatory activity. In this work, the effects of GBLP on the immune system in immunosuppressed mice were examined. Mice were divided into normal control, model, positive control, and high, medium, and low GBLP (800, 400, and 200 mg/kg˙bw) groups, with 12 mice in each group. An immunosuppressed mouse model was prepared using cyclophosphamide. After 28 days of gavage, peripheral blood lymphocytes were collected, and the thymus and spleen were removed and weighed. Splenic lymphocyte proliferation, cytokine secretion, mRNA expression, and TLR/MAPK signaling pathway-related protein expression were detected by MTT assay, ELISA, qRT-PCR, and western blotting, respectively. In comparison to the normal control group, the indices were significantly lower in the model group (p < 0.05). GBLP restored spleen, thymus, and lymphocyte proliferation indices, secretion and mRNA expression of IL-4, IFN-γ, IL-2, and IL-10, protein expression of TLR2, TLR4, MyD88, and IRAK4, and phosphorylation levels of JNK, ERK, and p38 in cyclophosphamide-treated mice (p < 0.05). The findings indicate that GBLP improved cyclophosphamide-induced immunosuppression in mice. Its mechanism of action involved the TLR/MAPK signaling pathways, implying that GBLP can be further developed as an immunomodulatory functional food component.