Supramolecular structure features and immunomodulatory effects of exopolysaccharide from Paecilomyces cicadae TJJ1213 in RAW264.7 cells through NF-κB/MAPK signaling pathways

Abstract

This study investigated the supramolecular structure features and immunomodulatory effects of two exopolysaccharide fractions (EPS1 and EPS2) from Paecilomyces cicada TJJ1213 in vitro. AFM images revealed that EPS1 and EPS2 displayed different morphological features at different concentrations. Congo red and XRD assay further proved that EPS1 and EPS2 mainly exhibited amorphous structure with random coil conformation in solution. Furthermore, the immunomodulatory effect of EPSs was investigated on RAW264.7 cells. Results showed that EPS1 and EPS2 could enhance the phagocytic activity and induce the NO production and could also significantly up-regulate the mRNA expression of iNOS, TNF-α, IL-6, IL-1β, IFN-γ and IL-4. Western blot assay analysis demonstrated that EPSs increased protein expression of TLR4 and the nuclear translocation of NF-κB p50/p65. Additionally, the phosphorylation levels of MAPKs proteins (p38, ERK and JNK) were also remarkably increased. Thus, EPSs could active TLR4-NF-κB/MAPKs signaling pathways to exert the immunomodulatory effect on macrophages.