Abstract 362: Pharmacologic Blockade Of Sodium-glucose Cotransporter-2 Inhibits Vascular Smooth Muscle Cell Calcification

Abstract

Background: Empagliflozin (Empa) is a highly selective sodium glucose cotransporter-2 (SGLT2) inhibitor used to reduce the risk of cardiovascular death. Empa reduces arterial stiffness and blood pressure in humans, as well as atherosclerosis and intimal hyperplasia in preclinical models, though the mechanisms underlying these effects are poorly defined. We investigated effects of Empa on the calcification of human coronary artery smooth muscle cells (SMCs). Methods: To determine the effect of Empa on SMC calcification triggered by high phosphate (HP) conditions, SMCs were cultured in standard ( i.e. , normal phosphate [NP]) medium, HP medium, or HP medium containing Empa (2.5 μM). After 12-days, SMC calcification was quantified by the alizarin red staining method with results quantified by comparison to a standard curve and normalized to NP control. Similar methods were used to study effects of Empa on SMC calcification induced by platelet-derived growth factor-BB (50 ng/mL). Effects of Empa on angiotensin II-induced SMC senescence, a precursor of cell calcification, were studied by quantifying senescence-associated β galactosidase activity. Real-time reverse transcriptase PCR was used to study gene expression of Runx2, a master regulator of SMC osteogenic transition. Results: Empa significantly decreased HP-induced SMC calcification (1.14±0.11 vs . 1.32±0.11 AU/mL, n=5, p<0.05) and PDGF-BB-induced calcification (1.20±0.17 vs . 1.94±0.22 AU/mL, n=5, p<0.05). Empa significantly inhibited SMC senescence (1.03±0.06 vs . 1.39±0.04, n=5, p<0.05), while decreasing Runx2 gene expression by 77±35% (n=6, p <0.01). Conclusion: Empa significantly inhibits SMC calcification triggered by clinically relevant pathophysiologic stimuli. Empa significantly inhibits SMC senescence and Runx2 gene expression, identifying molecular pathways underpinning Empa’s anti-calcific effect. These findings identify an additional mechanism by which Empa may decrease vascular stiffness and provide insights into how SGLT2 inhibitors exert beneficial effects on vascular diseases dependent on SMC calcification and senescence, including hypertension and atherosclerosis.