title: Attenuation of reperfusion lung injury and apoptosis by A2A adenosine receptor activation is associated with modulation of Bcl-2 and Bax expression and activation of extracellular signal-regulated kinases.
abstract: Adenosine receptors (AR) and extracellular signal-regulated kinases (ERK) have been implicated in tissue protection and apoptosis regulation during ischemia/reperfusion (I/R) injury. This study tests the hypothesis that reduction of reperfusion lung injury after A2A AR activation is associated with attenuation of apoptosis, modulation of ERK activation, and alterations in antiapoptotic and proapoptotic protein expression (Bcl-2 and Bax, respectively). Experiments were performed in intact-chest, spontaneously breathing cats in which the arterial branch of the left lower lung lobe was occluded for 2 h and reperfused for 3 h (I/R group). Animals were treated with the selective A2A AR agonist ATL313 given 5 min before reperfusion alone or in combination with the selective A2A AR antagonist ZM241385. Western blot analysis showed significant reduction in expression of Bcl-2 and increase in expression of Bax after reperfusion, compared with control lungs. Phosphorylated ERK1/2 levels were also increased after reperfusion. Compared with the I/R group, ATL313 markedly (P < 0.01) attenuated indices of injury and apoptosis including the percentage of injured alveoli, wet-dry weight ratio, myeloperoxidase activity, in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling-positive cells, and caspase 3 activity and expression. Furthermore, compared with reperfused lungs, in ATL313-pretreated lungs, Western blot analysis demonstrated substantial ERK1/2 activation, increased expression of Bcl-2, and attenuated expression of Bax. The protective effects of ATL313 were blocked by pretreatment with ZM241385. In summary, the present study shows that in vivo activation of A2A AR confers protection against reperfusion lung injury. This protection is associated with decreased apoptosis and involves ERK1/2 activation and alterations in antiapoptotic Bcl-2 and proapoptotic Bax proteins.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Hadassah University Medical Center, The Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Julia
authors.initials: J
authors.lastname: Rivo
authors.forename: Evelyne
authors.initials: E
authors.lastname: Zeira
authors.forename: Eithan
authors.initials: E
authors.lastname: Galun
authors.forename: Sharon
authors.initials: S
authors.lastname: Einav
authors.forename: Joel
authors.initials: J
authors.lastname: Linden
authors.forename: Idit
authors.initials: I
authors.lastname: Matot
mesh_terms: D058908:Adenosine A2 Receptor Agonists; D000818:Animals; D017209:Apoptosis; D002415:Cats; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D008168:Lung / Q000473:pathology*; D055370:Lung Injury; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000378:metabolism; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D015427:Reperfusion Injury / Q000378:metabolism*; D014227:Triazines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D014947:Wounds and Injuries; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
chemical_list: C510376:ATL 313; D058908:Adenosine A2 Receptor Agonists; D010880:Piperidines; D019253:Proto-Oncogene Proteins c-bcl-2; D043705:Receptor, Adenosine A2A; D014227:Triazines; D014230:Triazoles; C097270:ZM 241385; D051028:bcl-2-Associated X Protein; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3