A marine glycopeptide SP-2S1 isolated from Asterias amurensis enhances immune function by activating TLR4/NF-κB signaling pathway

In recent years, the outbreak frequency of Asterias amurensis along the northern coast of China has increased year by year. Its excessive proliferation has caused multi-dimensional hazards to coastal ecological stability, fishery sustainability and coastal related industries. Exploring its high-value utilization of resources has become an urgent need to solve the ecological governance dilemma. In this study, a marine glycopeptide, SP-2S1 (Molecular mass: 3 790 Da), was isolated and purified from Asterias amurensis. The structural characteristics of SP-2S1 was analyzed using FTIR, SDS-PAGE, and H-NMR. Monosaccharide composition analysis reveals that it predominantly contained mannose, rhamnose, and glucose at a molar ratio of 59.72∶15.58∶15.11, while amino acid profiling indicates high levels of glycine, aspartic acid, and proline at a ratio of 13.8∶8.6∶6.2. In vitro, SP-2S1 significantly enhanced the immune activity of RAW264.7 macrophages by promoting phagocytosis and increasing the secretion of NO, ROS, and inflammatory cytokines (IL-1β and TNF-α). Mechanistic studies show that SP-2S1 upregulated TLR4 and MyD88 expression, increased the phosphorylation of NF-κB p65, and activated the TLR4/NF-κB signaling pathway. These findings suggest that the marine glycopeptide SP-2S1 derived from A. amurensi has potential as an immunomodulator, which provides a basis for the high-value utilization of this species and for the development of marine glycopeptide-based immune adjuvants.