A2A adenosine receptor activation improves survival in mouse models of endotoxemia and sepsis

Background. Sepsis is currently treated with antibiotics and various adjunctive therapies that are not very effective. Methods. Mouse survival ( 4 - 5 days) and peritoneal and blood bacteria counts were determined after challenge with intraperitoneal lipopolysaccharide (LPS) or live Escherichia coli. Results. The A(2A) adenosine receptor (AR) agonist 4-{3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydrofuran- 2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester (ATL146e; 0.05 - 50 mug/kg) protected mice from challenge with LPS, and protection occurred when treatment was delayed up to 24 h after challenge. Deletion of the A(2A) AR gene, Adora2a, inhibited protection by ATL146e. A putative A(3)AR agonist, N-6- iodobenzyladenosine-5'-N-methyluronamide (IB-MECA; 500 mug/kg but not 5 or 50 mug/kg) protected mice from challenge with LPS. The protective effects of both ATL146e and IB-MECA were counteracted by the A(2A) AR selective antagonist 4-(2-[7-amino-2-[2-furyl][1,2,4] triazolo[2,3- a][1,3,5] triazin-5-yl- amino] ethyl)- phenol. In the live E. coli model, treatment with ATL146e (50 mug/kg initiated 8 h after infection) increased survival in mice treated with ceftriaxone (5 days) from 40% to 100%. Treatment with ATL146e did not affect peritoneal numbers of live E. coli at the time of death or 120 h after infection but did increase numbers of peritoneal neutrophils and decreased the number of live E. coli in blood. Conclusions. AR agonists increase mouse survival in endotoxemia and sepsis via A(2A) AR-mediated mechanisms and reduce the number of live bacteria in blood.