Hyperglycemic Adipocyte-Derived Exosomes Cause Oxidative Stress and Lipid Peroxidation in Brain Microvascular Endothelial Cells.

Background/Aims: Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia and is a risk factor for stroke. Our previous studies demonstrated that adipocyte-derived exosomes (Ad-EXs) mediate adipose-brain communication. This study investigated the effects of hyperglycemic subcutaneous and visceral Ad-EXs on brain microvascular endothelial cell (BMEC) dysfunction during ischemic injury. Hypothesis: Hyperglycemic Ad-EXs exacerbate stroke injury via inducing oxidative stress and lipid peroxidation in BMECs. Methods: EXs were isolated from primary human subcutaneous and visceral adipocytes cultured in normal glucose (NG): NG-S-Ad-EXs and NG-V-Ad-EXs, or high-glucose (HG, 25 mM) media: HG-S-Ad-EXs and HG-V-Ad-EXs by ultracentrifugation and characterized by a nanoparticle tracking analysis system. PKH26-labeled Ad-EXs were used to evaluate uptake mechanisms in human BMECs (HBMECs). Functional effects were assessed in hypoxia/reoxygenation (H/R)-injured HBMECs treated with different Ad-EXs. Oxidative stress and lipid peroxidation markers (NOX2/4, MDA, 4-HNE, and GPX4) were analyzed. Results: HG increased Ad-EX release from both adipocyte depots. HG-derived Ad-EXs increased HBMEC cytotoxicity and permeability while reducing angiogenesis after H/R injury. Mechanistically, HG-Ad-EXs promoted oxidative stress through increased NOX2/4 and lipid peroxidation via elevated MDA/4-HNE and reduced GPX4 expression. Conclusions: Hyperglycemic Ad-EX triggered oxidative stress via NOX2/4 and lipid peroxidation via MDA/4HNE/GPX4, leading to impaired HBMEC functioning, which was exacerbated in the H/R injury condition.