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Glucolipid metabolism disorder in diabetes mellitus (DM) causes human endothelial injury and autophagy dysfunction is an important cause of endothelial dysfunction (ED). Selenoprotein S (SelS) could protect endothelium from oxidative stress, inflammatory responses, and apoptosis. This study assessed the effect of SelS on autophagy in glucolipid metabolic disorders and protection of the resulted vascular endothelial injury. The results showed that high glucose (HG), high oxidized low-density lipoprotein (HL), and HG combined with HL (HGL) could reduce viability of human aortic endothelial cells (HAECs), induce HAECs injury and increase SelS expression in a time-dependent manner. HG, HL, and HGL also initially induced autophagy but later reduced it in HAECs, while activity of the Akt/mTOR signaling was inhibited, especially in HGL culture of HAECs. SelS overexpression reduced the endothelial injury and autophagy and activated the Akt/mTOR signaling in HG, HL and HGL-cultured HAECs, compared to the control. Conversely, knockdown of SelS expression had the opposite effects on HAECs. In conclusion, SelS demonstrated a protective effect on endothelial injury induced by high glucose and/or ox-LDL and the underlying molecular events might be related to its regulation of HAECs autophagy by activating the Akt/mTOR signaling. SelS could be a potential intervention target in prevention and treatment of diabetic vascular complications., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Endothelial dysfunction (ED) is a critical and initiating factor in the genesis of diabetic vascular complications whose occurrence and development is closely related to the complex intravascular microenvironment. However, currently, there is no dynamic model simulating the diabetic vascular endothelial microenvironment that can be used to investigate the mechanism underlying multifactor-induced ED. Here, we developed an integrated microfluidic chip as a new methodological platform to study vascular ED. Selenoprotein S (SELENOS) was found to be involved in the defense against oxidative stress-induced vascular endothelial injury in our previous studies. However, the regulatory signaling pathway underlying this process has not been described. With this chip, we demonstrated that multifactor-induced oxidative stress injury in human aortic endothelial cells (HAECs) has a synergistic effects and upregulates SELENOS expression. Subsequently, SELENOS was found to protect HAECs against multifactor-induced oxidative stress injury by regulating the PKCα/PI3K/Akt/eNOS pathway in the diabetic vascular endothelial microenvironment. Based on these data, our diabetic vascular chip provides a promising tool for studying vascular endothelial function, and SELENOS may be a novel target for prevention and treatment of diabetic macrovascular complications., Competing Interests: Declaration of competing interest Conflict of interest: The authors have no conflicts of interest to declare., (Copyright © 2020. Published by Elsevier Inc.)

Endothelial dysfunction, partly induced by inflammatory mediators, is known to initiate and promote several cardiovascular diseases. Selenoprotein S (SelS) has been identified in endothelial cells and is associated with inflammation; however, its function in inflammation-induced endothelial dysfunction has not been described. We first demonstrated that the upregulation of SelS enhances the levels of nitric oxide and endothelial nitric oxide synthase in tumor necrosis factor- (TNF-) α-treated human umbilical vein endothelial cells (HUVECs). The levels of TNF-α-induced endothelin-1 and reactive oxygen species are also reduced by the upregulation of SelS. Furthermore, SelS overexpression blocks the TNF-α-induced adhesion of THP-1 cells to HUVECs and inhibits the increase in intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Moreover, SelS overexpression regulates TNF-α-induced inflammatory factors including interleukin-1β, interleukin-6, interleukin-8, and monocyte chemotactic protein-1 and attenuates the TNF-α-induced activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways. Conversely, the knockdown of SelS with siRNA results in an enhancement of TNF-α-induced injury in HUVECs. These findings suggest that SelS protects endothelial cells against TNF-α-induced dysfunction by inhibiting the activation of p38 MAPK and NF-κB pathways and implicates it as a possible modulator of vascular inflammatory diseases. [ABSTRACT FROM AUTHOR]