Role of Sortilin and Matrix Vesicles in Nϵ-Carboxymethyl-Lysine-Induced Diabetic Atherosclerotic Calcification

Background and aims To investigate the role of Sortilin and matrix vesicles (MVs) in Ne-Carboxymethyl-lysine (CML)-induced diabetic atherosclerotic calcification (AC). Methods At human level, the correlation between Sortilin and CD9 (marker proteins of MVs) in serum MVs and CML in serum was explored by enzyme-linked immunosorbent assay (ELISA) detection and Pearson correlation analysis. After a diabetic apoE-/- mouse model was constructed, the calcification of aorta and the expressions of related proteins under CML and MVs injection were observed by calcification staining, immunofluorescence staining, and Western blot. MVs levels released by smooth muscle cells (SMCs) under different treatments was detected by nanometer tracking analysis (NTA). After treating SMCs with MVs and Anti-Sortilin, cell calcification was observed by Alizarin red staining. Results Serological analysis of patients showed that the concentrations of Sortilin and CD9 in serum MVs were positively correlated with the concentration of CML in serum. Animal experiments showed that CML could promote the progression of diabetic AC and the high expression of Sortilin in plaques. Diabetic apoE-/- mouse tail vein injection of CML-induced SMCs-derived MVs obviously aggravated AC. Cell experiment results showed that a high concentration of CML significantly promoted the release of MVs from SMCs. MVs from this source could markedly worsen cell calcification, while the administration of GW4869 (a widely used extracellular vesicles biogenesis inhibitor) significantly reduced cell calcification. Finally, treatment of high concentrations of CML could also promote the recruitment of Sortilin to MVs, and administration of Anti-Sortilin could markedly reduce cell calcification caused by MVs. Conclusion We proved that CML not only affects the release of MVs from SMCs but also affects the recruitment of Sortilin to MVs, thereby promoting diabetic AC. This discovery may provide a new strategy for targeted prevention of vascular calcification in diabetes.