Abstract
The aim of this study was to examine the effect of polysaccharides from Polygonatum sibiricum (PSP) on RAW 264.7 cells together with the underlying signaling pathways. Water-soluble polysaccharides were extracted from Polygonatum sibiricum and the immunological activity/mechanism was explored in depth in RAW 264.7 cells. Our results demonstrated that PSP induced dendritic-like morphological changes in RAW 264.7 cells, and increased the production of nitric oxide, TNF-α and IL-6 in a dose-dependent manner. Mechanistic studies revealed that PSP promoted the accumulation of TNF-α and IL-6 mRNA and caused IκB-α degradation and NF-κB p65 translocation into the nucleus at both the transcriptional and translational levels. The expression of iNOS, COX-2, NF-κB and phosphorylated p38 MAPK was upregulated in PSP-treated RAW 264.7 cells. Water-soluble polysaccharides possess immunological activity and the immunostimulatory mechanism may be attributed to the NF-κB and p38 MAPK pathways similar to the mechanism of lipopolysaccharides.