Secreted Frizzled-Related Protein 5 Ameliorates Vascular Calcification in a Rat Model of Chronic Kidney Disease through the Wnt/β-Catenin Pathway

Abstract

<b><i>Introduction:</i></b> Vascular calcification (VC) is highly prevalent and a major cardiovascular risk factor in chronic kidney disease (CKD) patients. Secreted frizzled-related protein 5 (SFRP5), an inhibitor of the Wnt pathway, is an adipokine with a positive effect on metabolic and cardiovascular diseases. Our previous in vitro study showed that SFRP5 attenuates high phosphate-induced calcification in vascular smooth muscle cells by inhibiting the Wnt/β-catenin pathway. Therefore, we hypothesized that SFRP5 may protect against CKD-associated VC (CKD-VC) through the same signalling. <b><i>Methods:</i></b> The rat model of CKD with VC was induced by 0.75% adenine combined with 1.8% high phosphate diet, which were administered with adenovirus vectors of SFRP5. We evaluated the SFRP5 effect on VC by von Kossa staining and calcium content analysis and osteogenic markers by immunohistochemistry and Western blot. The components of Wnt/ß-catenin signalling were also evaluated. <b><i>Results:</i></b> SFRP5 local and serum levels were significantly decreased in the CKD-VC rat model compared with the control group. Adenovirus-mediated overexpression of SFRP5 significantly inhibited VC, which was due to suppression of CKD-induced expression of calcification and osteoblastic markers. Additionally, SFRP5 abrogated activation of the Wnt/β-catenin pathway that plays a major role in the pathogenesis of VC. The specificity of SFRP5 for inhibition of VC was confirmed using an empty adenovirus as a control. <b><i>Conclusion:</i></b> Our results suggest that SFRP5 ameliorates VC of CKD rats by inhibiting the expression of calcification and osteoblastic markers as well as the Wnt/β-catenin pathway. Collectively, this study suggests that SFRP5 is a potential therapeutic target in CKD-VC.