Advanced Glycation End Products Induce Calcification of Vascular Smooth Muscle Cells Through RAGE/p38 MAPK

Background: Monckeberg's calcification in diabetes, known as medial artery calcification, is an independent predictor of cardiovascular mortality. However, the mechanism underlying this phenomenon remains to be elucidated. We demonstrate that advanced glycation end products (AGEs) induce calcification of vascular smooth muscle cells through the receptor for AGE (RAGE)/p38 mitogen-activated protein kinase (MAPK) signaling pathway.

Methods: We detected vascular calcification by von Kossa staining. Alkaline phosphatase (ALP) activity was determined by measuring p-nitrophenol. Osteocalcin concentrations were measured using ELISA. Western blotting for protein phosphorylation and real-time RT-PCR for expression of mRNA were used.

Results: AGEs induced calcification of vascular smooth muscle cells. AGEs also induced the expression of Runx2 mRNA. In addition, AGEs increased ALP activity and osteocalcin secretion. Furthermore, AGEs induced phosphorylation of p38 MAPK, and this phosphorylation was inhibited by the anti-RAGE blocking antibody. Increased ALP activity was inhibited by the p38 MAPK inhibitor or anti-RAGE blocking antibody. Furthermore, the p38 MAPK inhibitor and anti-RAGE blocking antibody both inhibited AGE-induced calcification of vascular smooth muscle cells. Diabetic serum induced calcification of smooth muscle cells and the calcification was inhibited by RAGE blocking.

Conclusion: Our findings indicate that AGEs induce calcification of vascular smooth muscle cells by osteoblast-like differentiation of smooth muscle cells through RAGE/p38 MAPK.