EphA2 monoclonal antibody attenuates hyperoxia-induced acute lung injury by preserving the alveolar-endothelial barrier.

Supplemental oxygen is essential for acute respiratory distress syndrome (ARDS); however, prolonged exposure to high-inspired oxygen fractions can cause hyperoxia-induced acute lung injury (HALI). Hyperoxia disrupts the alveolar–endothelial barrier through excess reactive oxygen species and inflammation, leading to edema, impaired gas exchange, and increased mortality. EphA2/ephrinA1 signaling regulates cytoskeletal dynamics and intercellular adhesion; however, its role in HALI remains unclear. We hypothesized that pharmacological EphA2 blockade would protect the alveolar–endothelial barrier. Male C57BL/6 J mice were exposed to > 95% O₂ for up to 72 h to establish HALI. Temporal changes in EphA2/ephrinA1 signaling, barrier proteins, and cytokines were assessed at 0, 24, 48, and 72 h. To evaluate therapeutic potential, mice exposed to 72 h hyperoxia received intravenous phosphate-buffered saline (PBS) or anti-EphA2 monoclonal antibody (mAb; 8 μg pretreatment). Lung injury was evaluated through histology, bronchoalveolar lavage (BAL) protein and cytokine levels, and the expression of junctional, apoptotic, and oxidative stress markers using western blotting and immunostaining. Survival was analyzed using Kaplan–Meier. Hyperoxia increased phosphorylated EphA2, disrupted VE-cadherin, ZO-2, and claudin-5, and elevated BAL protein and cytokine levels. EphA2 mAb pretreatment reduced histological injury, preserved junctional proteins, attenuated cytokine responses, enhanced Akt phosphorylation, decreased Bcl-2 levels, and reduced oxidative stress. Survival improved after 72 h of severe hyperoxia (p = 0.045). EphA2/ephrinA1 activation contributed to HALI. EphA2 mAb pretreatment mitigated lung injury and preserved barrier integrity, supporting EphA2 blockade as a potential barrier-protective strategy under severe hyperoxic stress.