Novel Anti-Inflammatory Action of 5-Aminoimidazole-4-carboxamide Ribonucleoside with Protective Effect in Dextran Sulfate Sodium-Induced Acute and Chronic Colitis

AMP-activated protein kinase (AMPK) is an important cellular energy sensor that is responsible for maintaining systemic and cellular energy balance. Its role in intestinal inflammation remains unclear. Recent studies indicate that AMPK activation initiated by 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) participates in modulating inflammatory responses. Inflammatory bowel disease (IBD) has been characterized by sustained intestinal mucosa inflammation, caused mainly by excessive macrophage activation and T helper type 1 (Th1) and Th17 immune responses. Thus, we sought to determine the effect of AICAR on inflammatory responses of murine models of IBD. Mice with acute or chronic colitis induced by dextran sulfate sodium (DSS) were treated with or without AICAR. Body weight and colon inflammation were evaluated, and production of proinflammatory cytokines in colon tissues was determined. Nuclear factor kappa B (NF-kappa B) activation in colon tissues was assayed, and Th1 and Th17 cell responses were also evaluated. By inducing AMPK activation, AICAR had a therapeutic effect in ameliorating acute and chronic DSS-induced murine colitis as shown by reduced body weight, loss and significant attenuation in clinical symptoms, and histological inflammation. Moreover, AICAR treatment inhibited NF-kappa B activation in macrophages, reduced levels of Th1- and Th17-type cytokines in colon tissues, and down-regulated Th1 and Th17 cell responses during the progress of acute and chronic experimental colitis. AICAR acts as a central inhibitor in immune responses of experimental colitis. Our data show that AICAR-initiated AMPK activation may represent a promising alternative to our current approaches to suppress intestinal inflammation in IBD.