Effects of Empagliflozin on Intermittent Hypoxia-Induced TRAF3IP2-Dependent Human Aortic Smooth Muscle Cell Proliferation

Abstract

Aims: Chronic intermittent hypoxia (IH), a characteristic feature of obstructive sleep apnea (OSA), contributes to cardiovascular diseases, including atherosclerosis, potentially through persistent oxidative stress and inflammation. TRAF3IP2 (TRAF3 Interacting Protein 2) is an oxidative stress-responsive proinflammatory adapter molecule and plays a causal role in a preclinical model of atherosclerosis. Since SGLT2 (Sodium/Glucose Cotransporter 2) inhibitors have shown protective effects in CVD by inhibiting oxidative stress and inflammation, we hypothesized that IH promotes the crosstalk between oxidative stress and TRAF3IP2, resulting in IL-6-dependent human aortic smooth muscle cell (SMC) proliferation, and that these effects are inhibited by the SGLT2 inhibitor empagliflozin. Materials and methods: Primary human aortic SMC were exposed to various cycles of IH. Normoxia served as a control. To understand the molecular mechanisms underlying IH-induced nitroxidative stress, TRAF3IP2 and IL-6 induction, and SMC proliferation and those targeted by empagliflozin were determined by treating SMC with various pharmacological inhibitors and viral vectors. Results: IH upregulated TRAF3IP2 expression, TRAF3IP2-dependent superoxide, hydrogen peroxide and nitric oxide generation, NF-kB and HIF-1a activation, IL-6 induction, and SMC proliferation. Exposure to IL-6 by itself induced SMC proliferation in part via TRAF3IP2, IL-6R, gp130, JAK, and STAT3. Further, SMC express SGLT2 at basal conditions, and is upregulated by both IH and IL-6. Importantly, empagliflozin inhibited IH-induced TRAF3IP2 upregulation, reactive oxygen and nitrogen species generation, TRAF3IP2-dependent HIF-1a and NF-kB activation, IL-6 induction, and IL-6-dependent JAK-STAT3-mediated SMC proliferation. Moreover, empagliflozin inhibited IL-6-induced STAT3-dependent SMC proliferation. Conclusions: These results suggest the therapeutic potential of empagliflozin in IH and inflammatory vascular proliferative diseases associated with OSA.