No abstract

Sodium-glucose co-transporter 2 (SGLT2) inhibitors improve cardiovascular outcomes in patients with type 2 diabetes mellitus (T2DM). Studies have also shown that canagliflozin directly acts on endothelial cells (ECs). Since heme oxygenase-1 (HO-1) is an established modulator of EC function, we investigated if canagliflozin regulates the endothelial expression of HO-1, and if this enzyme influences the biological actions of canagliflozin in these cells. Treatment of human ECs with canagliflozin stimulated a concentration- and time-dependent increase in HO-1 that was associated with a significant increase in HO activity. Canagliflozin also evoked a concentration-dependent blockade of EC proliferation, DNA synthesis, and migration that was unaffected by inhibition of HO-1 activity and/or expression. Exposure of ECs to a diabetic environment increased the adhesion of monocytes to ECs, and this was attenuated by canagliflozin. Knockdown of HO-1 reduced the anti-inflammatory effect of canagliflozin which was restored by bilirubin but not carbon monoxide. In conclusion, this study identified canagliflozin as a novel inducer of HO-1 in human ECs. It also found that HO-1-derived bilirubin contributed to the anti-inflammatory action of canagliflozin, but not the anti-proliferative and antimigratory effects of the drug. The ability of canagliflozin to regulate HO-1 expression and EC function may contribute to the clinical profile of the drug.

Cardiovascular disease is the major cause of morbidity and mortality in diabetes. Although numerous factors contribute to the development of diabetes‐associated cardiovascular disease, excessive proliferation and migration of vascular smooth muscle cells (SMCs) plays a critical role. Sodium‐glucose cotransporter 2 (SGLT2) inhibitors are the latest approved class of glucose lowering drugs. By blocking glucose uptake in the proximal tubule of the kidney, SGLT2 inhibitors induce glycosuria leading to decreases in fasting and postprandial glycemia. Notably, large multicenter clinical trials have demonstrated that SGLT2 inhibitors reduce cardiovascular disease and mortality in patients with type 2 diabetes. The mechanism underlying the cardiovascular benefits of SGLT2 inhibitors is not fully known; however, direct effects on vascular SMCs have not been considered. In the present study, we investigated the effect of three different SGLT2 inhibitors on vascular SMC function. Treatment of rat and human aortic SMCs with canagliflozin resulted in a potent, concentration‐dependent inhibition of cell proliferation and DNA synthesis. The anti‐proliferative effect of canagliflozin was observed at clinically relevant concentrations, and this was not seen with other SGLT2 inhibitors, including empagliflozin and dapagliflozin. The inhibition of SMC growth by canagliflozin occurred in the absence of cell death and was associated with the arrest of SMCs in the G0/G1 phase of the cell cycle. In addition, scratch‐wound assays found that vascular SMC migration was blocked by canagliflozin in a concentration‐dependent manner, whereas empagliflozin or dapagliflozin had no effect on SMC motility. In conclusion, the present study identified canagliflozin as a robust inhibitor of vascular SMC proliferation and migration. These inhibitory effects of canagliflozin are detected at pharmacologically relevant concentrations and are unique for this drug and not seen with other SGLT2 inhibitors. The ability of canagliflozin to exert these pleiotropic effects on vascular SMC function may contribute to the salutary cardiovascular actions of this drug in patients with type 2 diabetes. Support or Funding Information Supported by American Diabetes Association grant #1‐17‐IBS‐290.

Sodium‐glucose cotransporter‐2 (SGLT2) inhibitors are the newest class of glucose lowering drugs that act by inhibiting glucose reabsorption in the proximal tubule of the kidney. Recent clinical trials found that SGLT2 inhibitors reduce cardiovascular disease and mortality in patients with diabetes. The mechanism underlying the salutary actions of these drugs is not completely clear; however, it does not involve differential improvements in glycemic control. Given the critical role that endothelial cells (ECs) play in maintaining vascular homeostasis, the present study investigated the effect of the SGLT2 inhibitor canagliflozin on EC function. It also determined if the vasoprotective protein heme oxygenase‐1 (HO‐1) contributes to the cellular actions of the drug. Treatment of human umbilical vein ECs with clinically relevant concentrations of canagliflozin blocked cell proliferation, and this was associated with a pronounced decline in DNA synthesis. Canagliflozin also inhibited the migration of ECs following scrape injury in a concentration‐dependent manner. Incubation of ECs with a high concentration of glucose (25mM) and oxidized low‐density lipoprotein (oxLDL;50mg/L), which mimics the diabetic milieu, stimulated the adhesion of monocytes to ECs. However, treatment of ECs with canagliflozin markedly reduced the binding of monocytes to these cells. In addition, canagliflozin increased the expression of HO‐1 in a time and concentration‐dependent fashion, leading to a significant rise in endothelial HO‐1 activity. Finally, inhibition of HO‐1 activity or expression increased the adhesion of monocytes to glucose/oxLDL‐challenged ECs exposed to canagliflozin but had no effect on the proliferative or migratory response of canagliflozin‐treated ECs. In conclusion, the present study identifies canagliflozin as a key regulator of EC function. Moreover, it demonstrates that the induction of HO‐1 by canagliflozin contributes to the anti‐inflammatory action the drug. Thus, canagliflozin may exert some of its favorable effects in diabetes by limiting endothelial inflammation via the upregulation of HO‐1.