Protease signaling through protease activated receptor 1 mediate nerve activation by mucosal supernatants from irritable bowel syndrome but not from ulcerative colitis patients

PLoS One. 2018 Mar 12;13(3):e0193943. doi: 10.1371/journal.pone.0193943. eCollection 2018.

Abstract

Background & aims: The causes of gastrointestinal complaints in irritable bowel syndrome (IBS) remain poorly understood. Altered nerve function has emerged as an important pathogenic factor as IBS mucosal biopsy supernatants consistently activate enteric and sensory neurons. We investigated the neurally active molecular components of such supernatants from patients with IBS and quiescent ulcerative colitis (UC).

Method: Effects of supernatants from 7 healthy controls (HC), 20 IBS and 12 UC patients on human and guinea pig submucous neurons were studied with neuroimaging techniques. We identify differentially expressed proteins with proteome analysis.

Results: Nerve activation by IBS supernatants was prevented by the protease activated receptor 1 (PAR1) antagonist SCHE79797. UC supernatants also activated enteric neurons through protease dependent mechanisms but without PAR1 involvement. Proteome analysis of the supernatants identified 204 proteins, among them 17 proteases as differentially expressed between IBS, UC and HC. Of those the four proteases elastase 3a, chymotrypsin C, proteasome subunit type beta-2 and an unspecified isoform of complement C3 were significantly more abundant in IBS compared to HC and UC supernatants. Of eight proteases, which were upregulated in IBS, the combination of elastase 3a, cathepsin L and proteasome alpha subunit-4 showed the highest prediction accuracy of 98% to discriminate between IBS and HC groups. Elastase synergistically potentiated the effects of histamine and serotonin-the two other main neuroactive substances in the IBS supernatants. A serine protease inhibitor isolated from the probiotic Bifidobacterium longum NCC2705 (SERPINBL), known to inhibit elastase-like proteases, prevented nerve activation by IBS supernatants.

Conclusion: Proteases in IBS and UC supernatants were responsible for nerve activation. Our data demonstrate that proteases, particularly those signalling through neuronal PAR1, are biomarker candidates for IBS, and protease profiling may be used to characterise IBS.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Colitis, Ulcerative / metabolism*
  • Colitis, Ulcerative / pathology
  • Colitis, Ulcerative / surgery
  • Enteric Nervous System / drug effects
  • Enteric Nervous System / metabolism
  • Enteric Nervous System / pathology
  • Female
  • Guinea Pigs
  • Humans
  • Intestinal Mucosa / drug effects
  • Intestinal Mucosa / innervation
  • Intestinal Mucosa / metabolism*
  • Intestinal Mucosa / pathology
  • Irritable Bowel Syndrome / metabolism*
  • Irritable Bowel Syndrome / pathology
  • Irritable Bowel Syndrome / surgery
  • Male
  • Neurons / drug effects
  • Neurons / metabolism*
  • Neurons / pathology
  • Peptide Hydrolases / metabolism*
  • Protease Inhibitors / pharmacology
  • Proteomics
  • Receptor, PAR-1 / antagonists & inhibitors
  • Receptor, PAR-1 / metabolism*
  • Signal Transduction / drug effects
  • Tissue Culture Techniques

Substances

  • Protease Inhibitors
  • Receptor, PAR-1
  • Peptide Hydrolases

Grants and funding

This study was supported by grants from the Deutsche Forschungsgemeinschaft (DFG Sche 267/7-2 and GRK 1482) to MS, the European Union FP7 IPODD Consortium to GB and MS, the Research Foundation Flanders (Odysseus grant) to GB, and the NeuroGut Initial Training Network funded by the European Commission under the Seventh Framework Programme (PITN-GA-2013-607652) to MS, URL: http://www.neurogut.eu/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.