Objectives Proteases are key mediators of pain and altered enteric neuronal signalling, although the types and sources of these important intestinal mediators are unknown. We hypothesised that intestinal epithelium is a major source of trypsin-like activity in patients with IBS and this activity signals to primary afferent and enteric nerves and induces visceral hypersensitivity.
Design Trypsin-like activity was determined in tissues from patients with IBS and in supernatants of Caco-2 cells stimulated or not. These supernatants were also applied to cultures of primary afferents. mRNA isoforms of trypsin (PRSS1, 2 and 3) were detected by reverse transcription-PCR, and trypsin-3 protein expression was studied by western blot analysis and immunohistochemistry. Electrophysiological recordings and Ca2+ imaging in response to trypsin-3 were performed in mouse primary afferent and in human submucosal neurons, respectively. Visceromotor response to colorectal distension was recorded in mice administered intracolonically with trypsin-3.
Results We showed that stimulated intestinal epithelial cells released trypsin-like activity specifically from the basolateral side. This activity was able to activate sensory neurons. In colons of patients with IBS, increased trypsin-like activity was associated with the epithelium. We identified that trypsin-3 was the only form of trypsin upregulated in stimulated intestinal epithelial cells and in tissues from patients with IBS. Trypsin-3 was able to signal to human submucosal enteric neurons and mouse sensory neurons, and to induce visceral hypersensitivity in vivo, all by a protease-activated receptor-2-dependent mechanism.
Conclusions In IBS, the intestinal epithelium produces and releases the active protease trypsin-3, which is able to signal to enteric neurons and to induce visceral hypersensitivity.
- ABDOMINAL PAIN
- IRRITABLE BOWEL SYNDROME
- NERVE - GUT INTERACTIONS
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CR-F, AD-S, CC, CD and NV contributed equally.
Contributors CR-F, AD-S, CC, CL, JOJ, NC and J-PM have acquired data, have performed statistical analysis and have participated to manuscript drafting. PVB, MN, EC, SK, GP, DB, YT, ML, SV and LA have provided technical and/or material support. SV, CD and NV have participated to study concept and design, analysis and interpretation of data, drafting of the manuscript. CD and NV have supervised the study and have obtained funding.
Funding This work was supported by the Agence Nationale de la Recherche (R12177BB to NV), the Region Midi-Pyrénées (to CRF), the European Research Council (ERC-2012-StG-20111109) (to NV). The Toulouse Hospital for the COLIC project CC is a postdoctoral fellow of the Fonds voor Wetenschappelijk Onderzoek (FWO, Belgium). National Institutes of Health (NIH) grants DK088937 (to ML), NIH P30 DK41301 (models of GI function and disease core), NIH R01 DK57238 and NIH P50 DK064539 (both to YT) were also supporting parts of this study.
Competing interests None declared.
Patient consent Obtained.
Ethics approval French human ethics committee, Canada human ethics committee.
Provenance and peer review Not commissioned; externally peer reviewed.