N‐Acetylcysteine protects against cobalt chloride‐induced endothelial dysfunction by enhancing glucose‐6‐phosphate dehydrogenase activity

Abstract

Hypoxia‐induced endothelial dysfunction is known to be involved in the pathogenesis of several vascular diseases. However, it remains unclear whether the pentose phosphate pathway (PPP) is involved in regulating the response of endothelial cells to hypoxia. Here, we established an in vitro model by treating EA.hy926 (a hybrid human umbilical vein cell line) with cobalt chloride (CoCl 2 ; a chemical mimic that stabilizes HIF‐1α, thereby leading to the development of hypoxia), and used this to investigate the involvement of PPP by examining expression of its key enzyme, glucose‐6‐phosphate dehydrogenase (G6PD). We report that CoCl 2 induces the accumulation of HIF‐1α, leading to endothelial cell dysfunction characterized by reduced cell viability, proliferation, tube formation, and activation of cytokine production, accompanied with a significant decrease in G6PD expression and activity. The addition of 6‐aminonicotinamide (6‐AN) to inhibit PPP directly causes endothelial dysfunction. Additionally, N ‐Acetylcysteine (NAC), a precursor of glutathione, was further evaluated for its protective effects; NAC displayed a protective effect against CoCl 2 ‐induced cell damage by enhancing G6PD activity, and this was abrogated by 6‐AN. The effects of CoCl 2 and the involvement of G6PD in endothelial dysfunction have been confirmed in primary human aortic endothelial cells. In summary, G6PD was identified as a novel target of CoCl 2 ‐induced damage, which highlighted the involvement of PPP in regulating the response of endothelial cell CoCl 2 . Treatment with NAC may be a potential strategy to treat hypoxia or ischemia, which are widely observed in vascular diseases.

Oscillating Glucose Induces the Increase in Inflammatory Stress through Ninjurin-1 Up-Regulation and Stimulation of Transport Proteins in Human Endothelial Cells

“…In the present manuscript, we used an in vitro model, which mimics the increase in postprandial glucose after the ingestion of three daily meals, by simply exposing the ECs for 3 h to 25 mM glucose, followed by their incubation in 5 mM glucose for another 3 h. The use of the in vitro model may represent a limitation of our study, but the simplicity of the in vitro models makes them helpful in the attempt to understand part of the molecular mechanism representative for the in vivo systems. EA.hy926, the cells that were mostly used in this study, are a widely accepted model in the literature, being used for the identification of different molecular mechanisms, including those related to inflammatory stress or oxidative stress [ 74 , 75 , 76 ]. EA.hy926 cell line was also used successfully to evaluate the deleterious effects of diabetic conditions [ 77 , 78 ].…”

The influence of redox modulation on hypoxic endothelial cell metabolic and proteomic profiles through a small thiol‐based compound tuning glutathione and thioredoxin systems

“…ECs were set in hypoxia for different time points and combined with a redox modulator, I‐152, a co‐drug of NAC and MEA. The effects of hypoxic conditions on HUVEC have been already investigated and described in the literature, 69 and likewise the application of NAC and MEA separately in hypoxic studies in vitro and in vivo 70–73 . However, taking advantage of the ability of our molecule to release both compounds, overcoming their limitations, such as poor cellular uptake of NAC and MEA fast oxidation, 74,75 we wondered how I‐152 could restore hypoxia‐altered redox homeostasis in ECs.…”

Prolonged Hypoxic Exposure Impairs Endothelial Functions: Possible Mechanism of HIF-1α Signaling

“…To elucidate the involvement of HIF-1α in endothelial cell functions, we utilized cobalt chloride (CoCl2), a chemical agent known to stabilize HIF-1α, thereby inducing a mimetic hypoxic condition [20]. Our investigation revealed a notable increase in mitochondrial superoxide production in endothelial cells following CoCl2 treatment (Fig.…”