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Abstract
Background Mast cell activation is an important driver of abdominal pain in irritable bowel syndrome (IBS). While evidence supports the role of IgE-mediated mast cell activation in visceral pain development in IBS, the role of pseudoallergic MRGPRX2-mediated mast cell activation in this process remains unknown.
Objective We investigated whether MRGPRX2-mediated mast cell activation plays a role in abdominal pain development in patients with IBS.
Design MRGPRX2 expression in mast cells and other immune cells was characterised across colon layers using flow cytometry. We evaluated whether MRGPRX2 agonists trigger mast cell degranulation and transient receptor potential vanilloid 1 (TRPV1) sensitisation in healthy human colonic submucosal plexus samples using live imaging. Rectal biopsies were then collected from patients with IBS and healthy volunteers (HV) and MRGPRX2+ mast cell frequency, MRGPRX2 expression per cell, mast cell degranulation kinetics in response to MRGPRX2 agonists, MRGPRX2 agonistic activity and presence of MRGPRX2 agonists in biopsy supernatants were assessed.
Results MRGPRX2+ mast cells are enriched in the submucosa and muscularis of the healthy human colon. MRGPRX2 agonists induce mast cell degranulation and TRPV1 sensitisation in the healthy colon submucosa. While the frequency of rectal MRGPRX2+ mast cells was unaltered in IBS, submucosal mast cells showed increased degranulation in response to MRGPRX2 agonists in IBS compared with HV. MRGPRX2 agonistic activity was increased in IBS rectal biopsy supernatant compared with HV, which was associated with increased levels of substance P.
Conclusion The MRGPRX2 pathway is functionally upregulated in the colon of patients with IBS, supporting its role in abdominal pain in IBS.
- IRRITABLE BOWEL SYNDROME
- INTESTINAL MAST CELLS
- VISCERAL HYPERSENSITIVITY
- ABDOMINAL PAIN
Data availability statement
Data are available upon reasonable request.
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Data availability statement
Data are available upon reasonable request.
Footnotes
LD, MCE and SVR are joint first authors.
HH and GB are joint senior authors.
X @Visceral_Pain, @Diiind, @BoeckxstaensLab
Contributors LD, MCE, SVR, NS, AD-S, HH and GB planned and designed the experiments. MCE, SVR and MFV performed immunofluorescence staining of rectal biopsies and isolated submucosal plexus samples, which were analysed by HH and LD. MRGPRX2 FACS experiments were performed by HH and RQ and analysed by HH. SGC and SB performed the qPCR on human DRG. MCE performed and analysed Ca2+ imaging and mast cell degranulation experiments in intestinal tissue. LD performed and analysed Ca2+ experiments in CHO cells. LD, ZW and EDM performed gene expression experiments on rectal biopsies. LD and AD-S quantified MRGPRX2 agonists in biopsy supernatants. LD, MCE, SVR, NS, AD-S, HH and GB reviewed data. LD, MCE, SVR, HH and GB wrote and revised the manuscript. All other authors corrected and approved the final manuscript. GB is the guarantor of this manuscript.
Funding The Laboratory for Enteric Neuroscience (LENS) is supported by Hercules (AKUL/15/37_GOH1816N) and Research Foundation – Flanders, FWO (G.0929.15) grants awarded to Professor Pieter Vanden Berghe): Zeiss Examiner (Till Vision), Nikon inverted (Till Vision) microscope, fluorescence BX 41 Olympus and Zeiss LSM880 – Airyscan confocal microscope. LD and MFV were supported by an FWO PhD fellowship (11B8920N, 11C2219N), NS and SVR by an FWO postdoctoral fellowship (12V3619N, 1289225N). RQ and ZW were supported by a PhD scholarship provided by the China Scholarship Council. SB was supported by a National Health and Medical Research Council (NHMRC) of Australia Investigator Leadership Grant (APP2008727). This work is supported by a KU Leuven grant (C14/18/086), and FWO-WOG grant (W001620N) and by Takeda Pharmaceutical Company Limited (Osaka, Japan).
Competing interests Part of this study is supported by Takeda Pharmaceutical Company Limited (Osaka, Japan). GB is an Editorial Board Member of Gut. All remaining authors declare no conflicts of interest.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
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