Activation of A1, A2A, or A3 adenosine receptors attenuates lung ischemia-reperfusion injury

Objective

Adenosine and the activation of specific adenosine receptors are implicated in the attenuation of inflammation and organ ischemia-reperfusion injury. We hypothesized that activation of A₁, A_2A, or A₃ adenosine receptors would provide protection against lung ischemia-reperfusion injury.

Methods

With the use of an isolated, ventilated, blood-perfused rabbit lung model, lungs underwent 18 hours of cold ischemia followed by 2 hours of reperfusion. Lungs were administered vehicle, adenosine, or selective A₁, A_2A, or A₃ receptor agonists (CCPA, ATL-313, or IB-MECA, respectively) alone or with their respective antagonists (DPCPX, ZM241385, or MRS1191) during reperfusion.

Results

Compared with the vehicle-treated control group, treatment with A₁, A_2A, or A₃ agonists significantly improved function (increased lung compliance and oxygenation and decreased pulmonary artery pressure), decreased neutrophil infiltration by myeloperoxidase activity, decreased edema, and reduced tumor necrosis factor-α production. Adenosine treatment was also protective, but not to the level of the agonists. When each agonist was paired with its respective antagonist, all protective effects were blocked. The A_2A agonist reduced pulmonary artery pressure and myeloperoxidase activity and increased oxygenation to a greater degree than the A₁ or A₃ agonists.

Conclusion

Selective activation of A₁, A_2A, or A₃ adenosine receptors provides significant protection against lung ischemia-reperfusion injury. The decreased elaboration of the potent proinflammatory cytokine tumor necrosis factor-α and decreased neutrophil sequestration likely contribute to the overall improvement in pulmonary function. These results provide evidence for the therapeutic potential of specific adenosine receptor agonists in lung transplant recipients.

CTSNet classification: 12, 38, 38.1

Abbreviations and Acronyms: BAL, bronchoalveolar lavage, IR, ischemia-reperfusion, MPO, myeloperoxidase, PA, pulmonary artery, PGD, primary graft dysfunction, TNF-α, tumor necrosis factor-alpha