Selective adenosine-A2A activation reduces lung reperfusion injury following transplantation

Background: The adenosine-A(2A) receptor on the neutrophil is responsible for several anti-inflammatory actions. We hypothesized that DWH-146e, a selective adenosine-A(2A) agonist, would reduce lung reperfusion injury following transplantation. Methods: We used an isolated, whole blood-perfused, ventilated rabbit lung model. Donor rabbits underwent lung harvest after pulmonary arterial PGE(1) injection and Euro-Collins preservation solution hush, and lungs were preserved for 18 hours at 4 degrees C. Group I lungs (n = 9) served as control subjects. Group II lungs (n = 9) were reperfused with whole blood that was first passed through a leukocyte-depleting filter. In group III (n = 9), DWH-146e was added to the blood reperfusate (25 mu g/kg) immediately before reperfusion and was administered throughout the reperfusion period (1 mu g/kg/min). All lungs were reperfused for 30 minutes. Results: Arterial oxygenation in group II and group III was significantly higher than that of group I after 30 minutes of reperfusion (514.27 +/- 35.80 and 461.12 +/- 43.77 vs 91.41 +/- 20.58 mm Hg, p < .001). Pulmonary vascular resistance was significantly reduced in group III (22,783 +/- 357 dynes . s . cm(-5)) compared to both group II and group I: (31,057 +/- 1743 and 36,911 +/- 2173 dynes . s . cm(-5), p < .001). Airway compliance was improved in groups II and III when compared to group I (1.68 +/- 0.08 and 1.65 +/- 0.05 vs 1.36 +/- 0.13, p = .03). Microvascular permeability in group III was reduced to 106.82 +/- 17.09 compared with 165.70 +/- 21.83 ng Evans blue dye per gram of tissue in group I (p = .05). Group III myeloperoxidase activity was 39.88 +/- 4.87 compared with 88.70 +/- 18.69 Delta OD/g/min in group I (p = .03); group II myeloperoxidase activity was 56.06 +/- 7.46. Conclusions: DWH-146e reduced lung neutrophil sequestration and dramatically improved pulmonary graft function. Neutrophils are important components of the inflammatory cascade of reperfusion injury and their source may include both the circulating blood and the lung graft itself. Selective adensosine-A(2A) activation interrupts the neutrophil-mediated inflammatory response and reduces lung reperfusion injury following transplantation.