# Aβ40 Improves Cerebrovascular Endothelial Function via NOX4-Dependent Hydrogen Peroxide Release

## TL;DR

Aβ40 improves brain blood vessel function by releasing hydrogen peroxide through the NOX4 enzyme in endothelial cells.

## Contribution

This study identifies NOX4 as the key enzyme mediating Aβ40-induced hydrogen peroxide release in cerebrovascular endothelial cells.

## Key findings

- NOX4 is the predominant NADPH oxidase isoform in bEnd.3 mouse brain endothelial cells.
- Aβ40 increases hydrogen peroxide and nitric oxide release, enhancing endothelial cell viability.
- Pharmacological inhibition of NOX4 reduces Aβ40-induced hydrogen peroxide production.

## Abstract

Alzheimer’s disease (AD) is associated with an abnormal accumulation of amyloid β (Aβ) fibrils in the brain parenchyma and cerebrovasculature, which leads to cognitive impairment and cerebrovascular dysfunction. Cerebrovascular endothelial cells play a crucial role in regulating cerebral blood flow, vascular permeability, and neurovascular function. Reactive oxygen species (ROS), particularly those generated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2), contribute to vascular dysfunction and amyloid deposition in the Alzheimer’s disease (AD) brain. However, the role of the NOX4 isoform in AD pathogenesis remains to be examined. In the present study, we found that NOX4 among the NOX isoforms is predominantly expressed in bEnd.3 mouse brain endothelial cells. Treatment with Aβ40 significantly enhanced the release of H2O2 and NO, and increased the endothelial cell viability. To test the involvement of NOX4 in Aβ40-induced H2O2 production, we utilized pharmacological inhibitors of NOX isoforms. Aβ40-induced H2O2 production was attenuated in the presence of the pan-NOX inhibitor, apocynin, or the NOX1/4-selective inhibitors, setanaxib and GKT136901. Since only the NOX4 isoform is expressed in bEnd.3 cells, these results indicate that NOX4 is responsible for the release of H2O2 stimulated by Aβ40. Taken together, the present study demonstrated that Aβ40 peptide exerts beneficial effects in bEnd.3 endothelial cells via the NOX4-dependent mechanism.