Activation of NLRP3 inflammasome in RAW 264.7 cells by polysaccharides extracted from Grateloupia livida (Harv.) Yamada

Polysaccharides have been proven to be involved in the immune response in both anti-inflammation and pro-inflammation due to their distinct pharmacological properties. Recent studies showed that polysaccharides from Grateloupia livida (Harv.) Yamada possessed several biological activities, including anti-oxidant, anti-angiogenic, anti-cancer and antiviral. Our previous work has elucidated the structural features of the polysaccharides (named WGW) by combining ESI-MS with NMR and infrared (IR) spectroscopic analyses. The polysaccharides were mainly composed of galactose linked with sulfate ester, concluding to be μ-carrageenan and κ-carrageenan. The purpose of this study was to investigate the immunoregulation effects of WGW on macrophage RAW 264.7 cell. The cells were treated with WGW for different times, then Griess reagent was applied to detect the production of NO. The results presented that WGW induced the release of NO in large quantities (ranging from 2 µg/mL to 256 µg/mL) and improved the phagocytosis of macrophage RAW264.7 cells. Furthermore, WGW have a predominant role in the improvement of proinflammatory mediators, such TNF-α, IL-1β, iNOS, MMP-9 and COX2. Moreover, WGW activated NLRP3 inflammasome, in which MAPK/NF-κB signaling pathway played an important role. These results indicated WGW might be a potential immuno-stimulation drug to promote inflammation.