Separation of Dual Oxidase 2 and Lactoperoxidase Expression in Intestinal Crypts and Species Differences May Limit Hydrogen Peroxide Scavenging During Mucosal Healing in Mice and Humans

Alice Rigoni; Richard Poulsom; Rosemary Jeffery; Shameer Mehta; Amy Lewis; Christopher Yau; Eleni Giannoulatou; Roger Feakins; James O Lindsay; Mario P Colombo; Andrew Silver

doi:10.1093/ibd/izx024

Separation of Dual Oxidase 2 and Lactoperoxidase Expression in Intestinal Crypts and Species Differences May Limit Hydrogen Peroxide Scavenging During Mucosal Healing in Mice and Humans

Inflamm Bowel Dis. 2017 Dec 19;24(1):136-148. doi: 10.1093/ibd/izx024.

Authors

Affiliations

¹ Molecular Immunology Unit, Department of Research, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
² Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
³ Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK.
⁴ Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.
⁵ St Vincent's Clinical School, University of New South Wales, Sydney, NSW, Australia.
⁶ Department of Histopathology, The Royal London Hospital, London, UK.
⁷ Centre for Immunobiology, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.

PMID: 29272487
DOI: 10.1093/ibd/izx024

Abstract

Background: DUOX2 and DUOXA2 form the predominant H2O2-producing system in human colorectal mucosa. Inflammation, hypoxia, and 5-aminosalicylic acid increase H2O2 production, supporting innate defense and mucosal healing. Thiocyanate reacts with H2O2 in the presence of lactoperoxidase (LPO) to form hypothiocyanate (OSCN-), which acts as a biocide and H2O2 scavenging system to reduce damage during inflammation. We aimed to discover the organization of Duox2, Duoxa2, and Lpo expression in colonic crypts of Lieberkühn (intestinal glands) of mice and how distributions respond to dextran sodium sulfate (DSS)-induced colitis and subsequent mucosal regeneration.

Methods: We studied tissue from DSS-exposed mice and human biopsies using in situ hybridization, reverse transcription quantitative polymerase chain reaction, and cDNA microarray analysis.

Results: Duox2 mRNA expression was mostly in the upper crypt quintile while Duoxa2 was more apically focused. Most Lpo mRNA was in the basal quintile, where stem cells reside. Duox2 and Duoxa2 mRNA were increased during the induction and resolution of DSS colitis, while Lpo expression did not increase during the acute phase. Patterns of Lpo expression differed from Duox2 in normal, inflamed, and regenerative mouse crypts (P < 0.001). We found no evidence of LPO expression in the human gut.

Conclusions: The spatial and temporal separation of H2O2-consuming and -producing enzymes enables a thiocyanate- H2O2 "scavenging" system in murine intestinal crypts to protect the stem/proliferative zones from DNA damage, while still supporting higher H2O2 concentrations apically to aid mucosal healing. The absence of LPO expression in the human gut suggests an alternative mechanism or less protection from DNA damage during H2O2-driven mucosal healing.

Keywords: Duox2; colitis; gut pathogens; host defense; hydrogen peroxide; thiocyanate.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Colitis / chemically induced
Colitis / metabolism*
Colitis / pathology
Dual Oxidases / genetics
Dual Oxidases / metabolism*
Free Radical Scavengers / chemistry
Free Radical Scavengers / metabolism
Humans
Hydrogen Peroxide / metabolism*
Inflammation / metabolism*
Inflammation / pathology
Intestinal Mucosa / metabolism*
Intestinal Mucosa / pathology
Lactoperoxidase / genetics
Lactoperoxidase / metabolism*
Male
Mice
Mice, Inbred C57BL
Species Specificity
Wound Healing*

Substances

Free Radical Scavengers
Hydrogen Peroxide
Dual Oxidases
Lactoperoxidase