Contribution of bone marrow-derived cells to the pro-inflammatory effects of protease-activated receptor-2 in colitis

Abstract

ObjectiveOur aim was to determine the contribution of proteinase-activated receptor-2 (PAR2)-expressing bone marrow-derived cells on the development of colonic inflammation.MaterialsChimeric mice were generated by injecting bone marrow cells from wildtype (PAR2+/+) or PAR2 knockout mice (PAR2−/−) into irradiated PAR2+/+ or PAR2−/− mice. Treatments: Colitis was induced by giving 2.5% dextran sodium sulfate (DSS) solution for 7 days or by a single intracolonic administration of trinitrobenzene sulphonic acid (TNBS, 2 mg dissolved in 40% ethanol).MethodsSeven days after the induction of colitis, bowel thickness, inflammatory parameters [myeloperoxidase (MPO) activity, macroscopic/microscopic damage scores], and leukocyte trafficking (visualized via intravital microscopy) were assessed.ResultsTotal deficiency of PAR2 resulted in a marked reduction in severity of both TNBS and DSS induced colitis as assessed by MPO activity, macroscopic damage, bowel thickness, and leukocyte adherence. Colitis was attenuated in all chimeric lines in which there was loss of PAR2 in the host, non-bone marrow-derived tissue, independent of the status of PAR expression by bone marrow-derived cells. Interestingly, TNBS colitis was attenuated in PAR2+/+ chimeric mice with PAR2−/− derived bone marrow but these animals were not protected from DSS colitis.ConclusionsExpression of PAR2 by host-derived tissues plays a dominant role in regulating colonic inflammation. PAR2 expression by bone marrow-derived cells appears to play a role in TNBS colitis but not in DSS induced injury.Electronic supplementary materialThe online version of this article (doi:10.1007/s00011-010-0181-9) contains supplementary material, which is available to authorized users.