# Suppression of miR-195 attenuates oxygen–glucose deprivation/reperfusion-induced BBB destruction, possibly via targeting BCL2L2

## TL;DR

This study shows that reducing miR-195 helps protect brain blood vessels during stroke by preventing cell death and barrier damage.

## Contribution

The study identifies miR-195 as a novel therapeutic target for ischemic stroke by linking it to BCL2L2 and BBB integrity.

## Key findings

- miR-195 is upregulated in oxygen–glucose deprivation/reperfusion models and promotes cell apoptosis.
- miR-195 inhibition reduces BBB disruption and apoptosis in brain microvascular endothelial cells.
- miR-195 directly targets BCL2L2, and restoring BCL2L2 partially reverses miR-195-induced damage.

## Abstract

MicroRNAs (miRNAs) are highly expressed in the brain and represent promising therapeutic targets for the treatment of ischemic stroke. Previous studies have shown that microRNA-195 (miR-195) is associated with apoptosis and is significantly upregulated in the serum of patients with ischemic stroke. We aimed to confirm the role of miR-195 in brain microvascular endothelial cell (BMEC) apoptosis and blood–brain barrier (BBB) integrity.

bEnd.3 cells were exposed to oxygen–glucose deprivation/reperfusion (OGD/R). RT-qPCR was used to determine the relative expression of miRNA-195. Bioinformatics analysis using the TargetScan database predicted BCL2L2 as a potential target of miR-195. A BBB model was constructed by culturing bEnd.3 cells in the upper Transwell chambers. Transepithelial/transendothelial electrical resistance (TEER) and the fluorescein isothiocyanate (FITC)-dextran assay were used to assess BBB permeability. Immunofluorescence staining for caspase-3, TdT-mediated dUTP nick end labeling (TUNEL) staining, and flow cytometric analysis were used to measure bEnd.3 cell apoptosis. Tight junction proteins (TJPs) expression was determined using western blot analysis.

miR-195 expression was upregulated in the in vitro OGD/R model. miR-195 mimics exacerbated cellular apoptosis and BBB disruption following OGD/R, whereas the miR-195 inhibitor alleviated OGD/R-induced apoptosis and BBB impairment. Overexpression of miR-195 significantly reduced BCL2L2 expression, and luciferase reporter assays confirmed that miR-195 directly binds to BCL2L2. Co-transfection of miR-195 mimics and BCL2L2 partially reversed the effects of miR-195 mimics on cell survival and barrier function.

Our results suggest that the miR-195/BCL2L2 axis plays a critical role in the regulation of bEnd.3 cell apoptosis. Modulation of miR-195 may represent a novel therapeutic strategy for targeting BMEC apoptosis in ischemic stroke.