Induced peroxidase and cytoprotective enzyme expressions support adaptation of HUVECs to sustain subsequent H2O2 exposure

摘要

H2O2 mediates autocrine and paracrine signaling in the vasculature and can propagate endothelial dysfunction. However, it is not clear how endothelial cells withstand H2O2 exposure and promote H2O2-induced vascular remodeling. To understand the innate ability of endothelial cells for sustaining excess H2O2 exposure, we investigated the genotypic and functional regulation of redox systems in primary HUVECs following an H2O2 treatment.Primary HUVECs were exposed to two types of H2O2 treatments of both transient and consistent H2O2 exposure. Following H2O2 treatments for 24, 48 and 72 hr, we measured O ₂− production, mitochondrial membrane polarization (MMP), and gene expressions of pro-oxidative enzymes, peroxidase enzymes, and cytoprotective intermediates.Our results showed that the 24 hr H₂O₂ exposure significantly increased O₂⁻ levels, hyperpolarized MMP, and downregulated CAT, GPX1, TXNRD1, NFE2L2, ASK1, and ATF2 gene expression in HUVECs. At 72 hr, HUVECs in both treatment conditions were shown to adapt to reduce O₂⁻ levels and normalize MMP. An upregulation of GPX1, TXNRD1, and HMOX1 gene expression and a recovery of NFE2L2 and PRDX1 gene expression to control levels were observed in both consistent and transient treatments at 48 and 72 hr.The response of endothelial cells to excess levels of H₂O₂ involves a complex interaction amongst O₂⁻ levels, mitochondrial membrane polarization and anti- and pro-oxidant gene regulation. As a part of this response, HUVECs induce cytoprotective mechanisms including the expression of peroxidase and antioxidant enzymes along with the downregulation of pro-apoptotic genes. This adaptation assists HUVECs to withstand subsequent exposures to H₂O₂