Open AccessRANKL Inhibits the Production of Osteoprotegerin from Smooth Muscle Cells under Basal Conditions and following Exposure to Cyclic Strain
Author(s) -
Colin Davenport,
Emma Harper,
Keith D. Rochfort,
Hannah Forde,
Diarmuid Smith,
Philip M. Cummins
Publication year - 2018
Publication title -
journal of vascular research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 74
eISSN - 1423-0135
pISSN - 1018-1172
DOI - 10.1159/000486787
Subject(s) - osteoprotegerin , rankl , basal (medicine) , medicine , endocrinology , chemistry , strain (injury) , smooth muscle , activator (genetics) , receptor , insulin
Receptor activator of nuclear factor-κB ligand (RANKL) promotes vascular calcification, while osteoprotegerin (OPG) opposes it by blocking RANKL activity. It remains unclear which vascular cell populations produce and secrete OPG/RANKL. This study characterizes the production of OPG/RANKL from human aortic endothelial and smooth muscle cells (HAECs and HASMCs) under various conditions. HAECs and HASMCs were exposed to inflammatory stimuli (tumor necrosis factor-α or hyperglycemia) or physiological levels of hemodynamic (cyclic) strain. After 72 h, both cells and supernatant media were harvested for assessment of OPG/RANKL production. Based on initial findings, the experiments involving HASMCs were then repeated in the presence of exogenous RANKL. OPG was produced and secreted by HASMCs and (to a considerably lesser degree) HAECs under basal conditions. Inflammatory stimuli upregulated OPG production in both cell populations. Cyclic strain significantly upregulated OPG production in HASMCs. Neither cell population produced RANKL. Exposing HASMCs to exogenous RANKL inhibited basal OPG production and completely abrogated the strain-mediated upregulation of OPG. These data suggest that HASMCs are a significant source of OPG within the vasculature but that RANKL, once present, downregulates this production and appears capable of preventing the "protective" upregulation of OPG seen with HASMCs exposed to physiological levels of cyclic strain.