The Blockade of Adenosine Deaminase Ameliorates Chronic Experimental Colitis through the Recruitment of Adenosine A2A

Adenosine modulates immune/inflammatory reactions. This study investigates the expression of adenosine deaminase in the in-flamed colon, the effects of adenosine deaminase inhibitors on established colitis, and the recruitment of adenosine receptors by endogenous adenosine after adenosine deaminase blockade. Adenosine deaminase expression was determined by Western blot. The effects of 4-amino-2-(2-hydroxy-1-decyl)pyrazole[3,4-d]pyrimidine (APP; a novel adenosine deaminase inhibitor), erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA; a reference adeno-sine deaminase inhibitor), dexamethasone, and selective adeno-sine receptor antagonists were tested in rats with 2,4-dinitroben-zenesulfonic acid-induced colitis. Systemic (food intake, body and spleen weight) and colonic [macroscopic/microscopic damage, tumor necrosis factor- (TNF-), interleukin-6 (IL-6), and malon