Immunoenhancement effects of Ganoderma sinense peptides: Animal experiments, molecular mechanism and molecular docking

The objective of the study was to investigate the immunomodulatory activity of low-molecular-weight peptides from Ganoderma sinense protein hydrolysates (named GSP) both in vitro and in vivo, as well as to identify candidate peptides from GSP and elucidate their binding modes with the T cell receptor (TCR) through molecular simulation docking simulations. GSP appeared to exert immunoregulatory effects through the involvement of the Ca 2+ /CaN/NFATc1/IFN-γ signaling pathway in spleen lymphocytes. In cyclophosphamide-induced immunosuppressed mice, GSP treatment significantly increased spleen and thymus indices, repaired spleen tissue damage, and normalized WBC and RBC counts. Moreover, GSP significantly enhanced both cellular and humoral immunity by promoting the activities of T/B lymphocytes, macrophage phagocytosis, and NK cells, as well as by increasing serum IgM/IgG levels. Immunohistochemical analysis further suggested that GSP modulated NFAT- and NF-κB-related proteins in spleen tissue. Subsequently, fifteen candidate peptides were screened from GSP and docked with TCR using Autodock Vina. Among them, YGPAPPPR and FTPNAQIW were predicted to have strong binding affinities to TCR, primarily mediated by conventional hydrogen bonds, carbon‑hydrogen bonds, alkyl interactions, π-alkyl interactions and electrostatic interactions. These peptides should be regarded as candidate sequences for future structure-activity relationship studies. In conclusion, GSP may represent an effective immunomodulatory agent with potential applications in functional foods and dietary supplements.