D2 | Abstract 01

Annual NUTRIM Symposium 18 November 2020

FUNDAMENTAL SCIENCE

High mucin degradation of fecal water from Crohn’s disease patients, while individual epithelial barrier alteration in vitro

Heike E.F. Becker1,2, Alice Rustichelli1, Britt Heijnens1, Nader Kameli2,3, Frank Stassen2, John Penders2,4*, Daisy M.A.E. Jonkers1*
1Department of Gastroenterology/Hepatology, Division of Internal Medicine, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
2Department of Medical Microbiology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
3Department of Medical Microbiology, Faculty of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia
4Department of Medical Microbiology, Caphri School for Public Health and Primary Care, Maastricht University Medical Centre+, Maastricht, The Netherlands

*Authors contributed equally to this work.
Background:
 Crohn’s disease (CD) is a chronic inflammatory gastro-intestinal condition with a variable disease course. Both, impaired intestinal integrity and microbial dysbiosis play a role in the pathophysiology and occurrence of exacerbations. We hypothesized that a perturbed microbial activity in CD patients may contribute to the impaired barrier function. Therefore, this study aimed to examine the impact of bacterial products derived from fecal samples of either active CD patients, CD patients in remission or healthy controls on mucin degradation and intestinal epithelial barrier function in vitro.

Methods:
 Six healthy subjects and twelve CD patients were included. Disease activity was determined by endoscopic evaluation (SES-CD). Fresh fecal samples were collected within one week prior to endoscopy and processed to obtain fecal water (FW) within six hours. Bacterial membrane vesicles (MVs) were isolated from frozen samples using an ultrafiltration and size exclusion chromatography-based protocol. FW and MVs were applied on mucin agar plates to determine mucin degradation. Further, FW and MVs were applied on differentiated Caco-2 cell monolayers. The difference in transepithelial electrical resistance (TEER) and fluorescein-isothiocynate dextran 4 kDa (FITC-d4) flux was measured to detect paracellular junction disruption.

Results:
FW-induced mucin degradation was more pronounced in CD samples (median score 3.5) compared to healthy subjects (median score 1.125; p<0.01). FW resulted in 78-87% decrease of TEER in three remissive samples (p<0.001) and 15 and 30% increase of TEER in two active samples (p<0.05 and p<0.001, respectively). MVs did not induce detectable mucin degradation or changes in TEER or FITC-d4 permeation.

Conclusion:
The higher ability of CD patient-derived FW to degrade mucin might indicate contributions of mucin degrading bacteria and their products to CD pathophysiology and warrants further investigation. Moreover, the altered epithelial resistance in some individuals appears to be rather due to altered ion fluxes or nutrient exposure than paracellular alterations.

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