Selective adenosine-A2A activation reduces lung reperfusion injury following transplantation.

BACKGROUND: The adenosine-A2A receptor on the neutrophil is responsible for several anti-inflammatory actions. We hypothesized that DWH-146e, a selective adenosine-A2A 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 PGE1 injection and Euro-Collins preservation solution flush, 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 microg/kg) immediately before reperfusion and was administered throughout the reperfusion period (1 microg/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 x s x cm(-5)) compared to both group II and group I (31,057 +/- 1743 and 36,911 +/- 2173 dynes x s x cm(-5), p < .001). Airway compliance was improved in groups II and III when compared to group I (1.68 +/- 0.08 and 1.68 +/- 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 deltaOD/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 adenosine-A2A activation interrupts the neutrophil-mediated inflammatory response and reduces lung reperfusion injury following transplantation.

A novel cDNA restores reduced folate carrier activity and methotrexate sensitivity to transport deficient cells.

Mammalian cells accumulate reduced folates and methotrexate, a folate antagonist, through the reduced-folate carrier (RFC) (Goldman, I.D., Lichtenstein, N.S., and Oliverio, V.T. (1968) J. Biol. Chem. 243, 5007-5017). This study describes the isolation and expression of a cDNA clone that restores RFC activity to human breast cancer cells defective in this transporter. The cDNA cancer cells defective in this transporter. The cDNA codes for a peptide (mRFC1) of 58 kDa, whose hydropathy plot, resembling those of mammalian sugar transporters, predicts that it may be a member of a superfamily of transporter genes. Transfection of methotrexate-resistant (MTXR) ZR-75-1 cells with an expression vector, pRFC1, that codes for this peptide restores their ability to accumulate methotrexate. Furthermore, transport of methotrexate into pRFC1-transfected cells is blocked by a 10-fold molar excess of the reduced folate, 5-formyltetrahydrofolic acid, but is unaffected by folic acid. The increase in methotrexate uptake that is observed in pRFC1-transfected MTXR ZR-75-1 cells reverses their resistance to this antitumor agent.