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 P2Y6 receptors was assessed by bone marrow transplantation experiments and with a P2Y6 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. P2Y6 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 P2Y6 antagonist protected mice from DSS-induced intestinal inflammation in a dose-dependent manner. Finally, human intestinal epithelial cells express NTPDase8 and P2Y6 similarly as in mice.
Conclusion NTPDase8 protects the intestine from inflammation most probably by limiting the activation of P2Y6 receptors in colonic epithelial cells. This may provide a novel therapeutic strategy for the treatment of inflammatory bowel disease.
- gastrointestinal immune response
- intestinal epithelium
- inflammatory bowel disease
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Contributors MS participated in the design of the study, performed all experiments and drafted the manuscript. JL, JP and DGM contributed to several experiments. AD and LV provided their support for bone marrow experiments and analysis. MS, CJ and JS analysed the data. BR provided P2Y6 deficient mice. JS supervised the work. MS, JL, LV, BR, CJ and JS participated in the redaction of the manuscript.
Funding This work was supported by grants to JS from the Canadian Institutes of Health Research (PJT-156205) and from the Fondation du CHU de Québec. MS was the recipient of a scholarship from the Fonds de Recherche du Québec Santé (FRQS). DGM received a scholarship from the Foundation for the Coordination of Higher Education and Graduate Training (CAPES) and JS received a Chercheur National Scholarship award from the FRQS.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.
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