Raloxifene inhibits IL-6/STAT3 signaling pathway and protects against high-fat-induced atherosclerosis in ApoE−/− mice

The signal transducer and activator of transcription 3 (STAT3) pathway plays an important role in inflammatory cascade process. Our previous studies found that Raloxifene targeted against IL-6/GP130 protein-protein interface and inhibited STAT3 phosphorylation induced by IL-6 in cancer cells. However, whether Raloxifene could suppress IL-6/STAT3 signaling pathway and attenuate atherosclerosis in high-fat diet (HFD)-induced mice remains unknown. The objective of this study was to explore the potential effect of Raloxifene on the prevention of atherosclerosis. HFD-induced atherosclerosis was established in apoliprotein E-deficient (ApoE −/−) mice. Mice by daily intragastric gavage with Raloxifene or vehicle as controls were provided. The human umbilical vein endothelial cells (HUVEC), Rat VSMC and RAW264.7 cell lines were used to evaluate the effect of Raloxifene in vitro. We demonstrated that Raloxifene was effective in ameliorating HFD- induced atherosclerosis plaque burden and size. Histological analysis showed that the expression of IL-6, P-STAT3, ICAM-1, VCAM-1, CD68 and α-SMA were significantly decreased in the Raloxifene intervention group compared to HFD group. Moreover, we observed that IL-6 increased migration and cell viability of VSMCs and RAW264.7 cells, while Raloxifene treatment decreased migration and reduced cell viability of VSMCs and RAW264.7 cells stimulated by IL-6. Furthermore, this effect was related to blocking IL-6/STAT3 pathway. Raloxifene has effects on inhibiting atherosclerosis development, the underlying mechanisms might involve in inhibiting inflammation-related IL-6/STAT3 signaling pathway.