Mucolytic Bacteria With Increased Prevalence in IBD Mucosa... : Official journal of the American College of Gastroenterology | ACG (original) (raw)

ORIGINAL CONTRIBUTIONS: INFLAMMATORY BOWEL DISEASE

Mucolytic Bacteria With Increased Prevalence in IBD Mucosa Augment In Vitro Utilization of Mucin by Other Bacteria

Png, Chin Wen PhD1; Lindén, Sara K PhD1,2; Gilshenan, Kristen S MSc3; Zoetendal, Erwin G PhD4; McSweeney, Chris S PhD5; Sly, Lindsay I PhD6; McGuckin, Michael A PhD1; Florin, Timothy H J MD1

1Mucin and IBD Research Teams, Mucosal Diseases Program, Mater Medical Research Institute and Department of Medicine, University of Queensland, Mater Health Services, South Brisbane, Queensland, Australia

2Mucosal Immunobiology and Vaccine Center, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

3Mater Research Support Centre, Mater Health Services, South Brisbane, Queensland, Australia

4Laboratory of Microbiology, Wageningen University, HB Wageningen, The Netherlands

5CSIRO Livestock Industries, Queensland Bioscience Precinct, St Lucia, Queensland, Australia

6Centre for Bacterial Diversity and Identification, School of Chemistry & Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia

Correspondence: Timothy H.J. Florin, MD, Department of Medicine, University of Queensland, Mucin and IBD Research Teams, Mucosal Diseases Program, Mater Medical Research Institute, Level 3, Aubigny Place, Mater Health Services, South Brisbane, Queensland 4101, Australia. E-mail: [email protected]

published online 20 July 2010

SUPPLEMENTARY MATERIAL accompanies this paper at https://links.lww.com/AJG/B212

Received 22 March 2010; accepted 8 June 2010

Abstract

OBJECTIVES:

Mucosa-associated bacteria are increased in inflammatory bowel disease (IBD), which suggests the possibility of an increased source of digestible endogenous mucus substrate. We hypothesized that mucolytic bacteria are increased in IBD, providing increased substrate to sustain nonmucolytic mucosa-associated bacteria.

METHODS:

Mucolytic bacteria were characterized by the ability to degrade human secretory mucin (MUC2) in pure and mixed anaerobic cultures. Real-time PCR was used to enumerate mucosa-associated mucolytic bacteria in 46 IBD and 20 control patients. Bacterial mucolytic activity was tested in vitro using purified human MUC2.

RESULTS:

We confirm increased total mucosa-associated bacteria 16S rRNA gene in macroscopically and histologically normal intestinal epithelium of both Crohn's disease (CD) (mean 1.9-fold) and ulcerative colitis (UC) (mean 1.3-fold). We found a disproportionate increase in some mucolytic bacteria. Mean Ruminococcus gnavus were increased >4-fold and Ruminococcus torques ∼100-fold in macroscopically and histologically normal intestinal epithelium of both CD and UC. The most abundantly detected mucolytic bacterium in controls, Akkermansia muciniphila , was reduced many fold in CD and in UC. Coculture of A. muciniphila with MUC2 as the sole carbon source led to reduction in its abundance while it augmented growth of other bacteria.

CONCLUSIONS:

Mucolytic bacteria are present in healthy humans, where they are an integral part of the mucosa-associated bacterial consortium. The disproportionate increase in R. gnavus and R. torques could explain increased total mucosa-associated bacteria in IBD.