Clinical Trials Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. May 14, 2015; 21(18): 5635-5640
Published online May 14, 2015. doi: 10.3748/wjg.v21.i18.5635
Decreased expression of hyperpolarisation-activated cyclic nucleotide-gated channel 3 in Hirschsprung’s disease
Anne Marie O’Donnell, David Coyle, Prem Puri
Anne Marie O’Donnell, David Coyle, Prem Puri, National Children’s Research Centre, Our Lady’s Children’s Hospital, Crumlin, Dublin 12, Ireland
Author contributions: O’Donnell AM and Puri P contributed to study conception; O’Donnell AM and Coyle D performed the experiments; all authors contributed to drafting the manuscript; O’Donnell AM and Puri P drafted the final manuscript.
Supported by National Children’s Research Centre/Children’s Medical Research Foundation, Ireland.
Ethics approval: The study was reviewed and approved by the Temple Street Children’s University Hospital Research Ethics Committee No. 13.003.
Clinical trial registration: No clinical trial registration information is available for this study.
Informed consent: Informed written consent for participation in the study was provided by all parents and legal guardians of participants prior to enrollment in the study.
Conflict-of-interest: The authors declare that they have no conflict of interest.
Data sharing: Dataset is available from the corresponding author at prem.puri@ncrc.ie.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Prem Puri, Professor, MS, FRCS, FRCS (Ed), FACS, FAAP (Hon.), DSc (Hon.), National Children’s Research Centre, Our Lady’s Children’s Hospital, Cooley Rd, Crumlin, Dublin 12, Ireland. prem.puri@ucd.ie
Telephone: +353-1-4096420 Fax: +353-1-4550201
Received: October 9, 2014
Peer-review started: October 9, 2014
First decision: November 14, 2014
Revised: November 28, 2014
Accepted: December 19, 2014
Article in press: December 22, 2014
Published online: May 14, 2015
Processing time: 221 Days and 16.8 Hours
Abstract

AIM: To determine if hyperpolarisation-activated nucleotide-gated (HCN) channels exist in human colon, and to investigate the expression of HCN channels in Hirschsprung’s disease.

METHODS: We investigated HCN1, HCN2, HCN3 and HCN4 protein expression in pull-through specimens from patients with Hirschsprung’s disease (HSCR, n = 10) using the proximal-most ganglionic segment and distal-most aganglionic segment, as well as in healthy control specimens obtained at the time of sigmoid colostomy closure in children who had undergone anorectoplasty for imperforate anus (n = 10). Fluorescent immunohistochemistry was performed to assess protein distribution, which was then visualized using confocal microscopy.

RESULTS: No HCN1 channel expression was observed in any of the tissues studied. Both HCN2 and HCN4 proteins were found to be equally expressed in the aganglionic and ganglionic bowel in HSCR and controls. HCN3 channel expression was found to be markedly decreased in the aganglionic colon vs ganglionic colon and controls. HCN2-4 channels were seen to be expressed within neurons of the myenteric and submucosal plexus of the ganglionic bowel and normal controls, and also co-localised to interstitial cells of Cajal in all tissues studied.

CONCLUSION: We demonstrate HCN channel expression in human colon for the first time. Reduced HCN3 expression in aganglionic bowel suggests its potential role in HSCR pathophysiology.

Keywords: Hyperpolarisation-activated nucleotide-gated; Interstitial cells of Cajal; Hirschsprung’s; Pacemaker; Ih current

Core tip: Children with Hirschsprung’s disease experience symptoms of intestinal obstruction due to a spastically contracted aganglionic segment of distal bowel, however the mechanism for this spasticity is incompletely understood. Hyperpolarisation-activated nucleotide-gated channels play a key role in regulating cell excitability in both pacemaker and non-pacing cells. We examined expression of hyperpolarisation-activated nucleotide-gated (HCN) 1-4 in both Hirschsprung’s disease (HSCR) colon and healthy controls. While HCN-1 expression was absent, and HCN-2 and HCN-4 were expressed at similar levels in diseased and healthy bowel, we found HCN-3 to be reduced in aganglionic bowel in HSCR. We suggest deficient HCN3 channels may be involved in the pathophysiology of HSCR.