2018
JCI Insight. 2018 Oct 18;3(20). pii: 121521. doi: 10.1172/jci.insight.121521. [Epub ahead of print]
Coordination of ENT2-dependent adenosine transport and signaling dampens mucosal inflammation.
Department of Anesthesiology, Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado, USA. Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Digestive Health Institute, Children's Hospital Colorado, Aurora, Colorado, USA. Department of Pathology, University of Colorado School of Medicine, Aurora, Colorado, USA. Department of Anesthesiology, McGovern Medical School at UTHealth, Houston, Texas, USA. Department of Biochemistry and Molecular Biology, McGovern Medical School at UTHealth, Houston, Texas, USA.
Service type: Knockout mice
Abstract
Intestinal epithelial barrier repair is vital for remission in inflammatory bowel disease (IBD). Extracellular adenosine signaling has been implicated in promoting restoration of epithelial barrier function. Currently, no clinically approved agents target this pathway. Adenosine signaling is terminated by uptake from the extracellular space via equilibrative nucleoside transporters (ENTs). We hypothesized that ENT inhibition could dampen intestinal inflammation. Initial studies demonstrated transcriptional repression of ENT1 and ENT2 in IBD biopsies or in murine IBD models. Subsequent studies in mice with global Ent1 or Ent2 deletion revealed selective protection of Ent2-/- mice. Elevated intestinal adenosine levels in conjunction with abolished protection following pharmacologic blockade of A2B adenosine receptors implicate adenosine signaling as the mechanism of gut protection in Ent2-/- mice. Additional studies in mice with tissue-specific deletion of Ent2 uncovered epithelial Ent2 as the target. Moreover, intestinal protection provided by a selective Ent2 inhibitor was abolished in mice with epithelium-specific deletion of Ent2 or the A2B adenosine receptor. Taken together, these findings indicate that increased mucosal A2B signaling following repression or deletion of epithelial Ent2 coordinates the resolution of intestinal inflammation. This study suggests the presence of a targetable purinergic network within the intestinal epithelium designed to limit tissue inflammation.
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