HSPA12B promotes functional recovery after ischaemic stroke through an eNOS‐dependent mechanism

Stroke is the leading cause of disability worldwide. HSPA12B, a heat‐shock protein recently identified expression specifically in endothelial cells, is able to promote angiogenesis. Here, we have investigated its effects on functional recovery at chronic phase of ischaemic stroke. Ischaemic stroke was induced by 60 min. of middle cerebral artery occlusion in transgenic mice with overexpression of HSPA12B (HSPA12B Tg) and wild‐type littermates (WT). HSPA12B Tg mice demonstrated a significant higher survival rate than WT mice within 28 days post‐stroke. Significant improved neurological functions, increased spontaneous locomotor activity and decreased anxiety were detected in HSPA12B Tg mice compared with WT controls within 21 days post‐stroke. Stroke‐induced hippocampal degeneration was attenuated in HSPA12B Tg mice examined at day 28 post‐stroke. Interestingly, HSPA12B Tg mice showed enhanced peri‐infarct angiogenesis (examined 28 days post‐stroke) and hippocampal neurogenesis (examined 7 days post‐stroke), respectively, compared to WT mice. The stroke‐induced eNOS phosphorylation and TGF‐β1 expression were augmented in HSPA12B Tg mice. However, administration with eNOS inhibitor L‐NAME diminished the HSPA12B‐induced protection in neurological functional recovery and mice survival post‐stroke. The data suggest that HSPA12B promoted functional recovery and survival after stroke in an eNOS‐dependent mechanism. Targeting HSPA12B expression may have a therapeutic potential for the stroke‐evoked functional disability and mortality.