Wnt signaling contributes to vascular calcification by induction of matrix metalloproteinases.

Christian Freise,Uwe Querfeld,Nadja Kretzschmar

doi:10.1186/s12872-016-0362-8

Christian Freise, Uwe Querfeld + Show 1 more

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https://doi.org/10.1186/s12872-016-0362-8

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Abstract

BackgroundVascular calcifications such as arteriosclerosis, which is characterized by a calcificiation of the tunica media, represent major comorbidities e.g. in patients with chronic kidney disease (CKD). An essential step during the development of arteriosclerosis is the transdifferentiation/calcification of vascular smooth muscle cells (VSMC) resembling osteogenesis. The matrix metalloproteinases (MMP)-2 and −9 were shown to promote these VSMC calcifications and their inhibition is of therapeutic value to prevent arteriosclerosis in preclinical studies. Aiming for an understanding of the underlying regulatory mechanisms of MMPs we here investigated, if the MMP-mediated VSMC calcification involves altered signaling of the Wnt pathway, which is known to impact osteogenesis.MethodsWe used an experimental in vitro model of vascular calcification. Transdifferentiation/calcification of murine VSMC was induced by elevated calcium and phosphorus levels. Calcification was assessed by calcium and alkaline phosphatase measurements. Activation/activity of the gelatinases MMP-2 and MMP-9 was assessed by conversion of fluorescence-labelled substrates. Activation of the Wnt pathway was analysed by a reporter gene assay.ResultsBesides pro-calcifying culture conditions, also activation of Wnt signaling by a specific agonist (under normal culture conditions) stimulated VSMC-calcification accompanied by enhanced expression and secretion of the gelatinases MMP-2 and −9. Vice versa, recombinant MMP-2 and −9 induced a time-delayed activation of Wnt signaling after 72 h in VSMC but showed no direct effects after 24–48 h. These effects were blocked by pharmacological inhibition of MMPs or of Wnt signaling.ConclusionsOur study suggests that the pro-calcifying environment in CKD induces Wnt signaling in VSMC which in turn contributes to the induction of MMPs which then foster the development of arteriosclerosis. Thus, besides MMP inhibition, the inhibition of Wnt signaling in VSMC might represent a therapeutic target for the prevention of vascular calcifications.Electronic supplementary materialThe online version of this article (doi:10.1186/s12872-016-0362-8) contains supplementary material, which is available to authorized users.

Highlights

Vascular calcifications such as arteriosclerosis, which is characterized by a calcificiation of the tunica media, represent major comorbidities e.g. in patients with chronic kidney disease (CKD)
calcification medium (CM)-induced calcifications involve activation of Wnt signaling in vascular smooth muscle cells (VSMC) In a first set of experiments we investigated whether a calcifying environment alters the activation of Wnt signaling in VSMC
Since the gelatinases were previously shown to be involved in VSMC calcification [15] and are known to be upregulated by CM, we applied specific inhibitors for matrix metalloproteinases (MMP)-2, MMP-9 or both gelatinases in our experiments

Summary

Introduction

Vascular calcifications such as arteriosclerosis, which is characterized by a calcificiation of the tunica media, represent major comorbidities e.g. in patients with chronic kidney disease (CKD). An essential step during the development of arteriosclerosis is the transdifferentiation/calcification of vascular smooth muscle cells (VSMC) resembling osteogenesis. The matrix metalloproteinases (MMP)-2 and −9 were shown to promote these VSMC calcifications and their inhibition is of therapeutic value to prevent arteriosclerosis in preclinical studies. The development of arteriosclerosis is based on a process of biomineralization resembling osteogenesis [8, 9] This involves an extensive remodelling of the arterial extracellular matrix e.g. a changed composition of collagens, degradation of elastic fibres and transdifferentiation of vascular smooth muscle cells (VSMC) from a contractile to a chondroblast-like phenotype [10]. Increased matrix degradation by MMPs could provide an early signal in the pathophysiology of calcifications and inhibition of MMPs could be of therapeutic value

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