Loss of purinergic vascular regulation in the colon during colitis is associated with upregulation of CD39

Abstract

Neshat S, deVries M, Barajas-Espinosa AR, Skeith L, Chisholm SP, Lomax AE. Loss of purinergic vascular regulation in the colon during colitis is associated with upregulation of CD39. Am J Physiol Gastrointest Liver Physiol 296: G399 -G405, 2009. First published December 12, 2008 doi:10.1152/ajpgi.90450.2008.-Evidence from patients with inflammatory bowel disease (IBD) and animal models suggests that inflammation alters blood flow to the mucosa, which precipitates mucosal barrier dysfunction. Impaired purinergic sympathetic regulation of submucosal arterioles, the resistance vessels of the splanchnic vasculature, is one of the defects identified during IBD and in mouse models of IBD. We hypothesized that this may be a consequence of upregulated catabolism of ATP during colitis. In vivo and in vitro video microscopy techniques were employed to measure the effects of purinergic agonists and inhibitors of CD39, an enzyme responsible for extracellular ATP catabolism, on the diameter of colonic submucosal arterioles from control mice and mice with dextran sodium sulfate [DSS, 5% (wt/vol)] colitis. Using a luciferase-based ATP assay, we examined the degradation of ATP and utilized real-time PCR, Western blotting, and immunohistochemistry to examine the expression and localization of CD39 during colitis. Arterioles from mice with DSS colitis did not constrict in response to ATP (10 M) but did constrict in the presence of its nonhydrolyzable analog ␣,␤-methylene ATP (1 M). ␣,␤-Methylene ADP (100 M), an inhibitor of CD39, restored ATP-induced vasoconstriction in arterioles from mice with DSS-induced colitis. CD39 protein and mRNA expression was markedly increased during colitis. Immunohistochemical analysis demonstrated that, in addition to vascular CD39, F4/80-immunoreactive macrophages accounted for a large proportion of submucosal CD39 staining during colitis. These data implicate upregulation of CD39 in impaired sympathetic regulation of gastrointestinal blood flow during colitis. purinergic neurotransmission; ectonucleotidase; inflammation; sympathetic; vasoconstriction STUDIES OF PATIENTS WITH INFLAMMATORY bowel disease (IBD) and animal models of IBD have revealed alterations in gastrointestinal (GI) blood flow (2,15,22,26) and angiogenesis (4 -6). These changes may contribute to disease pathogenesis, inasmuch as defects in mucosal perfusion render the mucosal barrier susceptible to breakdown. One potential mechanism of altered mucosal blood flow is defective neural regulation of GI blood vessels during inflammation.Submucosal arterioles are the resistance vessels of the splanchnic vasculature and thus regulate mucosal perfusion (13,23,31). We previously identified a defect in sympathetic vasoconstrictor regulation of colonic submucosal arterioles in the 2,4,6-trinitrobenzene sulfonic acid (TNBS) mouse model of IBD (22). Neurally evoked vasoconstrictions in control mice were sensitive to ␣ 1 -adrenoceptor and purinergic receptor antagonism, and superfusion of ATP and phenylephrine caused robust vasoconstrictions. I...

Purinergic signalling in the gastrointestinal tract and related organs in health and disease

“…It has been suggested that ATP is a critical autocrine regulator of mechanosensitive 5-HT release, which is involved in the pathogenesis of IBD and that P2X3 receptors on enterochromaffin cells are downregulated in ulcerative colitis [442]. CD39 (NPTDase1) was upregulated in the submucosa during colitis that contributed to impaired sympathetic regulation of gastrointestinal blood flow, compromising epithelial barrier function [506]. Increase in sympathetic innervation of the mesenteric arteries supplying the colon was reported in inflamed human bowel [61].…”

Effects of Inflammation on the Innervation of the Colon

“…Purinergic neuromuscular transmission to the vascular and circular smooth muscle is reduced during experimental colitis in mice and rats (Antonioli et al 2010;Neshat et al 2009;Roberts et al 2012). ACh released from submucosal vasomotor neurons binds to endothelial muscarinic receptors, which stimulates endothelial NO synthase.…”

“…Nerve dysfunction may continue after clinical symptoms are no longer observed in the patient as there is often increased SNS activity in IBD patients while in clinical remission (Sharma et al 2009). Further, nerve dysfunction is not restricted to the inflamed region demonstrated by decreased norepinephrine in both the inflamed colon and the uninflamed small intestine during TNBS-induced colitis in rats (Blandizzi 2007;Jacobson, McHugh, and Collins 1995; Neshat, and Lomax 2009;Swain et al 1991) and dextran sulfate sodium (DSS)-induced colitis in mice . Recent research has made progress toward understanding the potential mechanisms underlying decreased noradrenaline release during colitis.…”

The Effects of Glycerl Trinitrate and Adenosine 5-Triphosphate on Activation of Potassium Channel-Mediated Vasorelaxation in Female rats aortic Smooth Muscle.

“…Smooth muscle cells express ligand-gated P2X receptors (P2XR) and G-protein-coupled P2Y receptors (P2YR), there is an emerging role of purinergic receptors as therapeutic targets in hypertension (Neshat et al, 2009). In vitro studies in a variety of tissues have demonstrated that ATP-mediated vasodilation is endothelium dependent and occurs through the activation of endothelial Gprotein-coupled P2Y receptors (Crecelius, et al, 2011).…”