Tryptase and Protease-Activated Receptor 2 Expression Levels in Irritable Bowel Syndrome

BACKGROUND/AIMS: Previous studies have revealed that mast cells (MCs) may activate the protease-activated receptors and release of neuropeptides involved in the pathogenesis of irritable bowel syndrome (IBS). The levels of protease-activated receptor 2 (PAR-2) and tryptase can contribute to understanding the pathogenesis of IBS. METHODS: Colonoscopic biopsies were performed of 38 subjects (20 with IBS-diarrhea [IBS-D], eight with IBS-constipation [IBS-C], and 10 healthy volunteers). The mRNA and protein levels of tryptase and PAR-2 were assessed by real-time PCR and Western blot. The levels of vasoactive intestinal peptide (VIP), substance P (SP), and calcitonin gene-related peptide (CGRP) were measured by immunohistochemistry, and MCs were counted by toluidine blue staining. RESULTS: Significant increases in the mRNA expression of tryptase (p<0.05, IBS-D, IBS-C vs control) and PAR-2 (p<0.05, IBS-D, IBS-C vs control) and in the tryptase protein level (p<0.05, IBS-D, IBS-C vs control) were detected in IBS. Elevations of MCs, CGRP, VIP and SP (p<0.05, IBS-D vs control) were observed for IBS-D only. CONCLUSIONS: Tryptase levels may upregulate the function of PAR-2, resulting in the release of neuropeptide and they were correlated with clinical symptoms associated with IBS.