Puerarin inhibits vascular calcification of uremic rats

The risk of cardiovascular events in patients with chronic kidney disease is tremendously increased due to vascular calcification. Local vascular inflammation significantly promotes vascular calcification. A previous study has shown that puerarin inhibits calcification of mouse vascular smooth muscle cells (VSMCs) in vitro, but whether puerarin can inhibit vascular calcification in vivo and the underlying mechanisms remain unclear. In this study, we found that rat VSMCs treated with calcifying medium showed more mineral deposition, and this effect was inhibited by puerarin in a dose-dependent manner, as detected by alizarin red staining and calcium content assay. Puerarin also prevented the trans-differentiation of VSMCs into osteoblast-like cells, indicated by down-regulation of bone-related genes including Runx2 and BMP2. In vivo study of uremic rats induced by renal nephrectomy further confirmed the inhibitory effect of puerarin on vascular calcification in uremic rats. Puerarin treatment significantly prevented mineral deposition in rat aortas and down-regulated the expression of Runx2 and BMP2. Furthermore, we detected the levels of pro-inflammatory cytokines including IL-1 beta, IL-6, IL-18 and TNF alpha in vitro and in vivo. The levels of IL-1 beta were remarkably increased in both calcified VSMCs and aortas of uremic rats, while puerarin treatment markedly decreased the expression of IL-1 beta. In addition, we found that puerarin reduced IL-1 beta possibly through targeting NLRP3/Caspasel/IL-1 beta and NF-kappa B signaling pathways and inhibiting the generation of reactive oxygen species. Taken together, we demonstrated that puerarin has the capability of inhibiting vascular calcification in uremic rats by inhibiting inflammation.