As-IV improves LPS-induced vascular endothelial dysfunction by inhibiting calpain-1/PI3K/Akt Signaling

Abstract Objective and design To explore the impacts and mechanisms of Astragaloside IV (AS-IV) on LPS-induced vascular endothelial dysfunction, which is often associated with the development of sepsis. Previous experimental and clinical studies have established the cardiovascular benefits of AS-IV, but the mechanism of action behind vascular endothelial dysfunction improvement remains unclear. Materials and methods In vivo studies, Capn1 -/- and wild-type C57BL/6 mice were gavaged with AS-IV (40, 80 or 120 mg/kg) for 7 days, except for the control group. The model of endotoxemia was established with a single intraperitoneal injection of LPS (10 mg/kg), in vitro studies, human aortic endothelial cells (HAECs) were pretreated with AS-IV, MDL-28170 (a calpain-1 inhibitor), and LY-294002 (a PI3K inhibitor) for 2 hours, afterwards, the cells were incubated with LPS (1 mg/L) for 24 hours. Vascular endothelial dysfunction was assessed by vascular reactivity testing, HE staining, western blotting, immunofluorescence staining and immunohistochemistry. Results Higher concentrations of LPS (1000 ng/ml) caused significant vascular endothelial dysfunction, however, AS-IV treatment enhanced ACh-induced vasodilatory responses, eNOS and NO production, reduced oxidative stress and inflammatory responses, and was accompanied by downregulation of calpain-1 and upregulation of PI3k and p-Akt in both mice and at the cellular level. Meanwhile, Capn1 -/- and MDL-28170 increased the expression of PI3K and P-Akt, delayed the onset and progression of vascular endothelial dysfunction and reduced oxidative stress and inflammatory responses, with pharmacological effects similar to those of AS-IV. In addition, LY-294002 significantly reduced AS-IV-mediated protection in vitro. Conclusion AS-IV ameliorated vascular endothelial dysfunction and may exert its protective effects through the calpain-1/PI3K/Akt signaling pathway.