Aldose reductase mediates endothelial cell dysfunction induced by high uric acid concentrations

Prior research has shown that uric acid (UA) can act as an antioxidant at normal concentrations. However, elevated UA levels may shift its role to a pro-oxidant. Established knowledge indicates that oxidative stress contributes to endothelial dysfunction, particularly in conditions like diabetes. Aldose reductase (AR) has been linked to oxidative stress pathways in diabetic complications. This gap motivated the current study to explore how high UA concentrations affect endothelial cells and whether AR is involved in this process. No prior work had resolved the specific interaction between UA concentration, AR activity, and reactive oxygen species (ROS) production. Understanding this mechanism is critical for identifying therapeutic targets in hyperuricemia-related diseases. The study aimed to clarify the role of AR in UA-induced oxidative stress. This uncertainty drove the investigation into AR inhibition as a potential protective strategy.

The study aimed to determine how high concentrations of uric acid (UA) lead to endothelial cell dysfunction and whether aldose reductase (AR) plays a role in this process. Researchers focused on the interaction between UA levels, AR activity, and reactive oxygen species (ROS) production. They sought to identify if AR inhibition could mitigate oxidative stress in hyperuricemic conditions. The specific problem addressed was the shift in UA’s function from antioxidant to pro-oxidant at high concentrations. This uncertainty drove the investigation into how UA concentration affects ROS components like O2•-, •OH, and 1O2. The study also aimed to determine if AR inhibition could reduce hydrogen peroxide (H2O2) production in vivo. The motivation stemmed from the need to clarify AR’s role in UA-induced endothelial dysfunction. This research could provide insight into therapeutic strategies for chronic kidney disease.

The study used cultured endothelial cells divided into three groups: control, 300 μM UA, and 600 μM UA. Researchers measured total reactive oxygen species (ROS) and four specific ROS components. They also assessed nitric oxide (NO) and NOX4 expression levels. The experiment included inhibiting NOX4 or AR to observe changes in ROS production. Serum H2O2 and von Willebrand factor (vWF) levels were measured in vivo to assess endothelial function. The study design involved controlled cell culture conditions and pharmacological inhibition. Researchers used epalrestat, an AR inhibitor, to test its effects on ROS and H2O2 levels. The approach combined in vitro and in vivo methods to evaluate AR’s role in oxidative stress.

High UA concentrations increased AR expression, which activated NADPH oxidase and enhanced ROS production. At 300 μM UA, levels of O2•-, •OH, and 1O2 decreased. However, at 600 μM UA, O2•- levels and downstream H2O2 production significantly increased. AR inhibition with epalrestat blocked these effects in cultured cells. In vivo, AR inhibition reduced H2O2 production in hyperuricemic mice. The study found that AR activity is closely linked to ROS and H2O2 levels. Epalrestat protected endothelial function by reducing oxidative stress markers. These findings suggest that AR inhibition could mitigate UA-induced endothelial dysfunction.

The study’s findings suggest that AR inhibition reduces oxidative stress in hyperuricemic conditions. Epalrestat blocked UA-induced ROS production and protected endothelial function. High UA concentrations shift from antioxidant to pro-oxidant roles via AR activation. AR inhibition could be a therapeutic strategy for hyperuricemia-related endothelial dysfunction. The results indicate that AR activity is essential for ROS and H2O2 production in endothelial cells. These findings provide new insight into UA’s role in chronic kidney disease. The authors propose that targeting AR may help preserve endothelial function in hyperuricemic patients. This study highlights the importance of AR in UA-induced oxidative stress.