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Physiological levels of bile acids increase bacterial uptake in colonic biopsies of collagenous colitis patients in remission
Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Surgery . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology.
Linköping University, Department of Clinical and Experimental Medicine, Surgery . Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology . Linköping University, Faculty of Health Sciences.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Objective: Patients with collagenous colitis (CC) have an impaired mucosal barrier. Moreover CC is associated with bile acid malabsorption. Bile acids may increase bacterial mucosal uptake in humans. To elucidate the possible role of bile acids in CC pathophysiology, the mucosal barrier function was investigated by exposing colonic biopsies to physiological concentrations of chenodeoxycholic acid (CDCA) or deoxycholic acid (DCA) in Ussing chamber experiments.

Patients/Interventions: The study included 33 individuals; 25 with collagenous colitis (14 in clinical remission without treatment, 11 with active disease, and 8 of these again after 6 weeks budesonide treatment); 8 healthy individuals undergoing screening colonoscopy served as controls. Endoscopic biopsies from the sigmoid colon were mounted in modified Ussing chambers and assessed for short circuit current (Isc), transepithelial resistance (TER), and transmucosal passage of chemically killed E. coli K12 after addition of 100 μmol/l CDCA or DCA. The biopsies were further investigated with confocal microscopy to asses bacterial transepithelial passage routes.

Results: By adding 100μmol/l CDCA or DCA the bacterial uptake was increased by 4-fold in biopsies of patients in remission; CDCA 6.5 units [2.5-9.8] and DCA 6.2 units [2.1-22] (median [IQR]), compared with uptake in biopsies without added bile acids 1.6 units [1.1-3]; (p=0.004 and p=0.01, respectively). In active disease and in patients in remission on budesonide, bile acids had no effect on bacterial uptake. Isc and TER were unaffected by the bile acids at 100μmol/l in all groups. Confocal microscopy demonstrated transepithelial passage of E.coli K12 via the paracellular route.

Conclusions: Physiological concentrations of dihydroxy-bile acids augment mucosal barrier dysfunction in colonic biopsies of patients with CC in remission. This leads to a substantially increased bacterial uptake that may contribute to relapse of inflammation. Budesonide seems to counteract the bile acid-induced mucosal impairment.

Keyword [en]
Microscopic colitis, permeability, intestinal mucosa, diffusion chamber, bile acids
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-56290OAI: oai:DiVA.org:liu-56290DiVA: diva2:318274
Available from: 2010-05-07 Created: 2010-05-07 Last updated: 2010-05-07
In thesis
1. Collagenous colitis: The influence of inflammation and bile acids on intestinal barrier function
Open this publication in new window or tab >>Collagenous colitis: The influence of inflammation and bile acids on intestinal barrier function
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background and aims: Collagenous colitis (CC) is a diarrheal disorder with an incidence rate of 5-6/100000 inhabitants, affecting mainly middle-aged women. The diagnosis is made by histology of the colonic mucosa. Classical findings are a thickened subepithelial collagenous layer and chronic inflammation in the lamina propria. In inflammatory bowel disease (IBD) the mucosal barrier function is important in pathogenesis. The main purpose of the thesis was therefore to describe the barrier function in CC. The cause of CC is uncertain but the condition seems to be associated with bile acid malabsorption. Increased faecal bile acids are known to induce diarrhea. In functional studies the influence of bile acids on mucosal permeability in biopsies of healthy human individuals and in patients with CC was investigated.

Methods and patients: In the first paper a single patient with intractable CC was examined before surgery, with loop-ileostomy and after bowel reconstruction. For the other studies a total of 25 patients with CC were included (20 women, 5 men, mean age 66 years). There were three groups (14 patients in clinical remission without medical treatment, 11 with active disease, and 8 of these again after 6 weeks of budesonide treatment); 17 individuals with normal histology served as controls. Endoscopic biopsies from the sigmoid colon were mounted in modified Ussing chambers and assessed for short-circuit current (Isc), transepithelial resistance (TER), and transmucosal passage of chemically killed E. coli K12 after addition of chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA). The biopsies were further investigated with confocal microscopy to assess bacterial transepithelial passage.

Results: Para- and transcellular permeability was increased in active CC, but normalized with histological improvement due to faecal stream diversion. After bowel reconstruction, permeability to CrEDTA and HRP increased again.

In CC, bacterial uptake in colonic biopsies was significantly higher in all groups than in controls. Despite significant alleviation of symptoms, budesonide did not normalize the increased bacterial passage. Histology was unchanged after 6 weeks of budesonide treatment. DCA augmented mucosal permeability to CrEDTA in a dose-dependent manner and even such a low dose as 100 μmol/l DCA increased bacterial uptake significantly. The combination of bile acids and E.coli K12 had additive effects on TER.

100 μmol/l CDCA and DCA increased bacterial uptake in biopsies of CC patients in remission 4-fold, but had no additive effect on biopsies from patients with active disease. Furthermore, patients in clinical remission on budesonide treatment showed no bile acidinduced effects on E.coli K12 passage.

Conclusion: Collagenous colitis presents with increased para/transcellular permeability and bacterial uptake, irrespective of disease activity or budesonide treatment, signifying an underlying mucosal barrier defect. Faecal stream diversion can normalize the barrier dysfunction, but budesonide does not, despite its beneficial clinical effects which alleviate diarrhea or bowel symptoms. Bile acids in physiological concentrations have the potential to augment bacterial uptake, especially in mucosa from CC patients in remission. Budesonide treatment appears to counteract the bile acid induced mucosal impairment. These detrimental effects of bile acids on mucosal barrier function might facilitate initiation and perpetuation of mucosal inflammation in CC.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 78 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1180
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-56291 (URN)978-91-7393-409-1 (ISBN)
Public defence
2010-05-21, Berzeliussalen, Campus US, Linköpings universitet, Linköping, 13:00 (English)
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Supervisors
Available from: 2010-05-07 Created: 2010-05-07 Last updated: 2012-03-22Bibliographically approved

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Münch, AndreasSöderholm, JohanCarlsson, AndersMagnusson, Karl-EricStröm, Magnus

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Gastroenterology and Hepatology Faculty of Health SciencesSurgery Centre of Surgery and OncologyMedical Microbiology Department of Clinical and Experimental MedicineLocal Health Care Services in Central Östergötland
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