D2 | Abstract 12

Annual NUTRIM Symposium 18 November 2020

FUNDAMENTAL SCIENCE

Immunoglobulin A coating of feces-derived bacterial vesicles as a marker of inflammatory bowel disease in humans

Nader Kameli1,2, Heike Becker1,3, Daisy Jonkers3, John Penders1, Paul Savelkoul1,4, Frank Stassen1

1 Department of Medical Microbiology, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University Medical Center+, Maastricht, The Netherlands.
2 Department of Medical Microbiology, Faculty of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia.
3Department of Gastroenterology/Hepatology, NUTRIM school of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands.
4Dept of Medical Microbiology and Infection Control, VU University medical center, Amsterdam, The Netherlands.
IgA plays a crucial role in maintaining the balance between the host and the gastrointestinal microbiota. Recent studies suggested that pronounced IgA coating is especially prominent among inflammatory commensals which drive intestinal disease. Membrane vesicles (MVs, nano-sized particles released by bacteria) have also been found to interact with the host and modulate development and function of the immune system. However, their interaction with IgA has not been studied yet. Here we developed a method to isolate and characterize the MVs from fecal samples and checked for possible differences in IgA coating patterns of MVs in health and disease.

MVs were isolated from fecal samples of 6 healthy controls (HC), 6 patients with active Crohn’s disease (CD) and 6 CD patients in a remissive state. Quantification and verification have been done with tunable resistive pulse sensing (TRPS-based analysis) bead-based flow-cytometer (BBFC) and transmission electron microscope (TEM). MVs were selected with specific antibodies for capturing (Gram+: LTA, Gram-: OmpA) followed by PE-conjugated anti-human IgA antibodies as detection.

We isolated 3.3*1010 - 2.6*1011 particles/1g of feces. MVs derived from healthy controls were significantly more coated compare to CD patient groups. In details, for selected G-ve derived MVs : 60% of the total population of MVs derived from HC were coated, 20 % from remissive CD patients, and <5 % of active CD patients; and for selected G+ve derived MVs : 55% of the total population of MVs derived from HC were coated, 34 % from remissive CD patients , and 25 % of active CD patients.

Here we demonstrate for the first time that MV isolated from the fecal samples are also coated with IgA, and surprisingly MVs from healthy volunteers were more densely coated than MVs from diseased patients. The possible consequence of this difference remains to be determined in future studies.
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NUTRIM aims to contribute to health maintenance and personalised medicine by unraveling lifestyle and disease-induced derangements in metabolism and by developing targeted nutritional, exercise and drug interventions. This is facilitated by a state of the art research infrastructure and close interaction between scientists, clinicians, master and PhD students.
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