Activation of the A3 adenosine receptor suppresses superoxide production and chemotaxis of mouse bone marrow neutrophils

Abstract

Adenosine is formed in injured/ischemic tissues, where it suppresses the actions of essentially all cells of the immune system. Most of the anti-inflammatory actions of adenosine have been attributed to signaling through the Gs protein-coupled A2A adenosine receptor (AR). Here, we report that the A3AR is highly expressed in murine neutrophils isolated from bone marrow. Selective activation of the A3AR with (2S,3S,4R,5R)-3-amino-5-[6-(2,5-dichlorobenzylamino)purin-9-yl] -4-hydroxytetrahydrofuran-2-carboxylic acid methylamide (CP-532,903) potently inhibited mouse bone marrow neutrophil superoxide generation and chemotaxis induced by various activating agents. The selectivity of CP-532,903 was confirmed in assays using neutrophils obtained from A2AAR and A 3AR gene "knockout" mice. In a model of thioglycollate-induced inflammation, treating mice with CP-532,903 inhibited recruitment of leukocytes into the peritoneum by specifically activating the A3AR. Collectively, our findings support the theory that the A 3AR contributes to the anti-inflammatory actions of adenosine on neutrophils and provide a potential mechanistic explanation for the efficacy of A3AR agonists in animal models of inflammation (i.e., inhibition of neutrophil-mediated tissue injury). Copyright © 2008 The American Society for Pharmacology and Experimental Therapeutics.