NTPDase8 protects mice from intestinal inflammation by limiting P2Y6 receptor activation: identification of a new pathway of inflammation for the potential treatment of IBD

Objective Nucleotides are danger signals that activate inflammatory responses via binding P2 receptors. The nucleoside triphosphate diphosphohydrolase-8 (NTPDase8) is an ectonucleotidase that hydrolyses P2 receptor ligands. We investigated the role of NTPDase8 in intestinal inflammation. Design We generated NTPDase8-deficient (Entpd8(-/-)) mice to define the role of NTPDase8 in the dextran sodium sulfate (DSS) colitis model. To assess inflammation, colons were collected and analysed by histopathology, reverse transcriptase-quantitative real-time PCR (RT-qPCR) and immunohistochemistry. P2 receptor expression was analysed by RT-qPCR on primary intestinal epithelium and NTPDase8 activity by histochemistry. The role of intestinal P2Y(6) receptors was assessed by bone marrow transplantation experiments and with a P2Y(6) receptor antagonist. Results NTPDase8 is the dominant enzyme responsible for the hydrolysis of nucleotides in the lumen of the colon. Compared with wild-type (WT) control mice, the colon of Entpd8(-/-) mice treated with DSS displayed significantly more histological damage, immune cell infiltration, apoptosis and increased expression of several proinflammatory cytokines. P2Y(6) was the dominant P2Y receptor expressed at the mRNA level by the colonic epithelia. Irradiated P2ry6(-/-) mice transplanted with WT bone marrow were fully protected from DSS-induced intestinal inflammation. In agreement, the daily intrarectal injection of a P2Y(6) antagonist protected mice from DSS-induced intestinal inflammation in a dosedependent manner. Finally, human intestinal epithelial cells express NTPDase8 and P2Y(6) similarly as in mice. Conclusion NTPDase8 protects the intestine from inflammation most probably by limiting the activation of P2Y(6) receptors in colonic epithelial cells. This may provide a novel therapeutic strategy for the treatment of inflammatory bowel disease.

Automated summary

NTPDase8 plays a protective role in intestinal inflammation by limiting the activation of P2Y(6) receptors in colonic epithelial cells, providing a potential novel therapeutic strategy for inflammatory bowel disease. Interventions targeting P2Y(6) receptors may protect against inflammation in the colon.