Abstract 4119062: A KLF2-BMPER-Smad1/5 checkpoint regulates high fluid shear stress-mediated artery remodeling

Background: Vascular remodeling to match arterial diameter to tissue metabolic requirements commonly fails in ischemic disease. Endothelial cell (EC) sensing of elevated fluid shear stress (FSS) from blood flow induces vessel outward remodeling to restore physiological FSS, but mechanisms are poorly understood. The Smad1/5 pathway, which is maximally activated at physiological FSS and suppressed at higher flow, opposes activation of Akt, suggesting that inhibiting Smad1/5 may be required for outward remodeling. Methods: In vitro flow studies used ECs in a parallel plate flow chamber. In vivo mouse studies used a carotid-jugular fistula model to induce high flow outward remodeling in the carotid artery, and femoral artery ligation to examine recovery from ischemia and arteriogenesis in the hindlimb. Results: Suppression of Smad1/5 at high FSS is mediated KLF2-dependent induction of the BMP pathway inhibitor BMPER, which suppresses Smad1/5 and de-inhibits Akt. In a mouse arteriovenous fistula (AVF) model, high FSS induces arterial outward remodeling coincident with elevated BMPER expression and Smad1/5 inactivation. Endothelial BMPER deletion impaired blood flow recovery and vascular remodeling in the AVF and a hindlimb ischemia (HLI) model, with the latter reversed by BMP9/10 blocking antibodies (bAbs). In both STZ-induced type 1 and HFD-induced type 2 diabetic mice that show poor recovery from HLI, BMP9/10 bAbs improved outcomes. Conclusions: Suppression of Smad1/5 through a KLF2-BMPER pathway is required for high FSS-mediated outward remodeling. Mimicking this pathway with BMP9/10 antibodies improves vascular remodeling in diabetic mice, suggesting a potential new therapeutic approach for ischemic disease.