Irisin-αV/β5 signaling attenuates endothelial dysfunction after intracerebral hemorrhage by preserving SLC25A39-mediated mitochondrial GSH import

Following intracerebral hemorrhage (ICH), the migration of neutrophils into the brain and the subsequent formation of neutrophil extracellular traps (NETs) play pivotal roles in promoting secondary neurological damage. Brain microvascular endothelial cells (BMECs) normally restrict immune cell entry across the blood-brain barrier. However, after ICH, BMECs upregulate cell adhesion molecules (CAMs) to facilitate neutrophil transendothelial migration (TEM). Targeting this endothelial-neutrophil axis thus represents a promising therapeutic strategy. Circulating irisin levels were measured in patients with ICH to evaluate clinical correlations. Experimental ICH models were established using wild-type, Fndc5-deficient, endothelial-specific Slc25a39 knockout, and endothelial-specific Sting knockout mice to assess the role of irisin in CAM expression, neutrophil TEM, NETosis, and neuronal injury. In ICH patients, lower circulating irisin levels correlated with larger perihematomal edema volume and elevated sICAM-1 and sVCAM-1 levels, serving as an independent predictor of poor outcomes. In murine models, genetic deficiency of the irisin precursor Fndc5 exacerbated endothelial CAM upregulation, neutrophil TEM, NETosis, and neuronal death, whereas exogenous irisin administration mitigated these pathologies. Mechanistically, irisin activated endothelial integrin αV/β5-FAK-PI3K-Akt signaling, which inhibited AFG3L2-mediated proteolysis of the mitochondrial GSH transporter SLC25A39. This stabilization sustained mitochondrial GSH import, reducing mtROS accumulation, preventing mPTP opening and mtDNA leakage, and thereby suppressing cGAS-STING-driven endothelial inflammation. Furthermore, endothelial-specific Slc25a39 knockout abrogated the neuroprotective effects of irisin, whereas endothelial Sting ablation phenocopied irisin-mediated protection. The irisin-SLC25A39-GSH-STING axis regulates endothelial inflammation by preserving mitochondrial redox homeostasis, offering a promising strategy to limit neutrophil-mediated secondary injury after ICH.