Poria cocos polysaccharides attenuated ox-LDL-induced inflammation and oxidative stress via ERK activated Nrf2/HO-1 signaling pathway and inhibited foam cell formation in VSMCs

Oxidative stress, inflammation, and foam cell formation in vascular smooth muscle cells (VSMCs) are considered to play crucial roles in the pathogenesis of atherosclerosis. Poria cocos polysaccharides (PCP) has been shown to possess anti-inflammatory, antitumor and anti-oxidative properties. In this study we explored the effects of PCP on ox-LDL-induced inflammation, oxidative stress and foam cell formation in VSMCs. PCP significantly attenuated ox-LDL-induced oxidative stress, as evidenced by the decreased reactive oxygen species (ROS) and MDA levels, and the increased SOD activity in VSMCs. PCP suppressed the induction effect of ox-LDL on inflammatory cytokines and inflammatory mediators. PCP also substantially inhibited VSMCs foam cell formation and intracellular lipids accumulation. Mechanistically, PCP suppressed ox-LDL-induced up-regulation of LOX-1, which is responsible for ox-LDL uptake. Western blotting suggested that PCP activated ERK1/2 signaling pathway, increased Nrf2 translocated from cytoplasm to nucleus and heme oxygenase-1 (HO-1) expression. Up-regulation of PCP on Nrf2/HO-1 signaling was reversed by pretreatment with ERK inhibitor PD98059, indicating the involvement of ERK in PCP activation of Nrf2/HO-1 signaling. In conclusion, these results demonstrated that PCP exerted its protection against oxidative stress and inflammation via the ERK/Nrf2/HO-1 signaling pathway and that PCP may be a promising candidate for the therapy of atherosclerosis.