Increased calcification in osteoprotegerin-deficient smooth muscle cells: Dependence on receptor activator of NF-?B ligand and interleukin 6.

ABSTRACT: Vascular calcification is highly correlated with cardiovascular disease morbidity and mortality. Osteoprotegerin (OPG) is a secreted decoy receptor for receptor activator of NF-?B ligand (RANKL). Inactivation of OPG in apolipoprotein E-deficient (ApoE-/-) mice increases lesion size and calcification. The mechanism(s) by which OPG is atheroprotective and anticalcific have not been entirely determined. We investigated whether OPG-deficient vascular smooth muscle cells (VSMCs) are more susceptible to mineralization and whether RANKL mediates this process.Lesion-free aortas from 12-week-old ApoE-/-OPG-/- mice had spotty calcification, an appearance of osteochondrogenic factors and a decrease of smooth muscle markers when compared to ApoE-/-OPG+/+ aortas. In osteogenic conditions, VSMCs isolated from ApoE-/-OPG-/- (KO-VSMC) mice deposited more calcium than VSMCs isolated from ApoE-/-OPG+/+ (WT-VSMC) mice. Gene expression and biochemical analysis indicated accelerated osteochondrogenic differentiation. Ablation of RANKL signaling in KO-VSMCs rescued the accelerated calcification. While WT-VSMCs did not respond to RANKL treatment, KO-VSMCs responded with enhanced calcification and the upregulation of osteochondrogenic genes. RANKL strongly induced interleukin 6 (IL-6), which partially mediated RANKL-dependent calcification and gene expression in KO-VSMCs.OPG inhibits vascular calcification by regulating the procalcific effects of RANKL on VSMCs and is thus a possible target for therapeutic intervention.

SUBMITTER: Callegari A 

PROVIDER: S-EPMC4057981 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature