Mechanism of the anti-inflammatory activity by a polysaccharide from Dictyophora indusiata in lipopolysaccharide-stimulated macrophages

Dictyophora indusiata polysaccharides (DIP) shows antioxidant, anti-tumor and immunostimulatory activities. However, the anti-inflammatory roles of DIP in NLRP3 inflammasome in LPS-stimulated macrophages are still not well defined. In this study, we investigated the mechanism of the anti-inflammatory activity of DIP in LPS-primed RAW264.7 macrophages. Our data showed that DIP inhibited NF-κB signal pathway via modulating TLR4 expression, phosphorylation of IκBα and nuclear translocation of NF-κB-p65 subunit. Meanwhile, DIP reduced inflammasome activation via decreasing NLRP3 expression in cytoplasmic pools, limiting self-assembly of NLRP3 inflammasome, as well as the subsequent activation of caspase-1 and the secretion of IL-1β and IL-18. For the first time, we show that the anti-inflammatory activity of DIP is mediated by inhibiting TLR4/NF-κB signal pathway and NLRP3 inflammasome activation during LPS-induced acute inflammation in RAW264.7 macrophages.