Immunomodulation of RAW264.7 cells by CP80-1, a polysaccharide of Cordyceps cicadae , via Dectin-1/Syk/NF-κB signaling pathway

Cordyceps cicadae is a rare edible and medicinal entomogenous fungus. Here, the structural characteristics and immunomodulatory activity of C. cicadae polysaccharide CP80-1 were preliminarily elucidated. It showed that CP80-1 of 250.431 kDa was mainly composed of glucose, xylose and rhamnose. Physiologically, CP80-1 can regulate the immune of RAW264.7 cells by promoting the proliferation, phagocytosis, and secretion of nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)−1β, and interleukin (IL)−6. However, these effects were significantly attenuated when Dectin-1 receptor expression was inhibited by laminarin. Moreover, laminarin down-regulated the mRNA levels of relevant genes, inhibited CP80-1-driven expression of proteins related to spleen tyrosine kinase (Syk) and nuclear factor kappa-B (NF-κB) signaling pathway. Additionally, CP80-1 induced the nuclear translocation of NF-κB subunit p65 in RAW264.7 cells. These results suggest that CP80-1 may activate RAW264.7 cells by regulating the Dectin-1/Syk/NF-κB signaling pathway, which provides theoretical basis for the development of C. cicadae in immunomodulation.