Attenuation of Pulmonary Ischemia-Reperfusion Injury by Adenosine A_2B Receptor Antagonism

Background Ischemia-reperfusion injury (IRI) is a major source of morbidity and mortality after lung transplantation. We previously demonstrated a proinflammatory role of adenosine A_2B receptor (A_2BR) in lung IR injury. The current study tests the hypothesis that A_2BR antagonism is protective of ischemic lungs after in vivo reperfusion or ex vivo lung perfusion (EVLP). Methods Mice underwent lung IR with or without administration of ATL802, a selective A_2BR antagonist. A murine model of EVLP was also used to evaluate rehabilitation of donation after circulatory death (DCD) lungs. DCD lungs underwent ischemia, cold preservation, and EVLP with Steen solution with or without ATL802. A549 human type 2 alveolar epithelial cells were exposed to hypoxia-reoxygenation (HR) (3 hours/1 hour) with or without ATL802 treatment. Cytokines were measured in bronchoalveolar lavage (BAL) fluid and culture media by enzyme-linked immunoassay (ELISA). Results After IR, ATL802 treatment significantly improved lung function (increased pulmonary compliance and reduced airway resistance and pulmonary artery pressure) and significantly attenuated proinflammatory cytokine production, neutrophil infiltration, vascular permeability, and edema. ATL802 also significantly improved the function of DCD lungs after EVLP (increased compliance and reduced pulmonary artery pressure). After HR, A549 cells exhibited robust production of interleukin (IL)-8, a potent neutrophil chemokine, which was significantly attenuated by ATL802. Conclusions These results demonstrate that A_2BR antagonism attenuates lung IRI and augments reconditioning of DCD lungs by EVLP. The protective effects of ATL802 may involve targeting A_2BRs on alveolar epithelial cells to prevent IL-8 production. A_2BR may be a novel therapeutic target for mitigating IRI to increase the success of lung transplantation.