Davenport Colin, Harper Emma, Rochfort Keith D, Forde Hannah, Smith Diarmuid, Cummins Philip M
School of Biotechnology, Dublin City University, Dublin, Ireland.
National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
J Vasc Res. 2018;55(2):111-123. doi: 10.1159/000486787. Epub 2018 Apr 10.
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.
核因子κB受体激活剂配体（RANKL）促进血管钙化，而骨保护素（OPG）通过阻断RANKL活性来对抗血管钙化。目前尚不清楚哪些血管细胞群产生并分泌OPG/RANKL。本研究对人主动脉内皮细胞和平滑肌细胞（HAECs和HASMCs）在各种条件下OPG/RANKL的产生情况进行了表征。将HAECs和HASMCs暴露于炎症刺激（肿瘤坏死因子-α或高血糖）或生理水平的血流动力学（周期性）应变。72小时后，收集细胞和上清培养基以评估OPG/RANKL的产生。基于初步研究结果，随后在存在外源性RANKL的情况下重复涉及HASMCs的实验。在基础条件下，HASMCs产生并分泌OPG，HAECs也产生（程度要小得多）。炎症刺激上调了两种细胞群中OPG的产生。周期性应变显著上调了HASMCs中OPG的产生。两种细胞群均不产生RANKL。将HASMCs暴露于外源性RANKL会抑制基础OPG的产生，并完全消除应变介导的OPG上调。这些数据表明，HASMCs是脉管系统中OPG的重要来源，但RANKL一旦存在，就会下调这种产生，并且似乎能够阻止在暴露于生理水平周期性应变的HASMCs中看到的OPG“保护性”上调。
