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

Abstract

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

Hydrogen peroxide modulates energy metabolism and oxidative stress in cultures of permanent human Müller cells MIO‐M1

“…JC‐10 staining, however, clearly indicated a hyperpolarization of the mitochondrial membrane under H 2 O 2 in our experiments. While mitochondrial H 2 O 2 release is triggered by their inner membrane potential , exogenous H 2 O 2 may result in a more complex regulation of the mitochondrial membrane potential . High concentrations (800 µM for 24 hours) of H 2 O 2 have been shown to reduce the ratio of red to green fluorescence of JC‐10, and thus the mitochondrial potential, dramatically in neonatal rat cardiac myocytes .…”

Protective effects of beet (Beta vulgaris) leaves extract against oxidative stress in endothelial cells in vitro

“…In addition, the involvement of NADPH oxidase family has been reported to increase the SODs expression in endothelial cells (Frey, Ushio‐Fukai, & Malik, ). Patel, Chen, and Kavdia ()) reported that SOD2 expression is transient, according to our H 2 O 2 treatment in HUVECs, decreasing after 72 hr compared to other antioxidative enzymes. Regarding catalase, similar effects have been observed in another study with HUVECs, showing its level decreases after H 2 O 2 treatment and increase after a phenolic‐rich extract treatment (Soares et al, ).…”

Differential induction of nuclear factor-like 2 signature genes with toll-like receptor stimulation

“…Our experiments using the antioxidant NAC showed that NAC had no effect on LPS-or PMA-induced PRDX1 nor on TXNRD1 expression, but did reduce HMOX1 expression suggesting that this is a more redox-sensitive gene (Figure 4). It is known that PRDX1, TXNRD1 and HMOX1 are induced by oxidative stress, but the results presented here suggest that some genes may be more susceptible to changes in redox state than others [39]. A study with HOCl has shown that HMOX1 is induced at lower HOCl concentrations, with the extent of induction similar to the one we observed:…”