Jari Verbunt* [1,2], Johan Jocken [2], Lars Vliex [2], John Penders [1], Ellen Blaak [2], Paul Savelkoul [1] and Frank Stassen [1]
*Presenting author, 1: Department of Medical Microbiology, infectious diseases & Infection prevention, Maastricht University Medical Center+, 2: Department of Human Biology, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University
Introduction: The microbiome plays a pivotal role in human health, and gut-borne inflammatory signalling (metabolic endotoxemia) is believed involved in the etiology of metabolic syndrome. Gut-bacteria produce factors such as bacterial membrane vesicles (bMVs) affecting host physiology. bMVs carry inflammatory toll-like receptor (TLR) ligands. Dysbiosis of the microbiota yields abnormal vesicle repertoires. This study investigates the nature and characteristics of human gut-derived bMVs following microbiota disruption with vancomycin antibiotic, and restoration through supplementation with 2’-fucosyllactose (2FL) prebiotic.
Methods: Feces-derived bMVs were isolated from 37 participants with overweight/obesity (BMI 25-40 kg/m^2) and normal glucose-tolerance (i) at baseline, (ii) after a 7-day course of vancomycin, and (iii) after 8 weeks of 2FL supplementation or placebo (maltodextrin). Isolated bMVs were assessed with respect to size, concentration, protein content, TLR2/4 activation, cytokine induction potential in THP-1 macrophages, and the nature of associated DNA (using 16S rDNA sequencing).
Results: Both TLR2 (mean OD644 0.35 to 0.55, p<0.001) and TLR4 (mean OD644 0.46 to 1.39, p<0.0001) activation increased under stimulation with post vancomycin bMVs. THP-1 macrophages stimulated with a normalized baseline vesicle pool produced on average 26 pg/mL Interleukin-6 in vitro vs 44 pg/mL for a normalized post-vancomycin vesicle pool (p<0.001). Proinflammatory traits were concomitant to increased Enterobacterales and Clostridia vadinBB60 group Order signatures. Parameters returned to baseline equally efficiently under 2FL and PLA supplementation.
Discussion/Conclusion: This study demonstrates, for the first time, how vancomycin alters the inflammatory properties of human gut bMVs. These dysbiotic vesicles are more effective at activating the host innate immune system ex vivo, and could contribute to metabolic disease. Further research into their nature and functionalities is required to unlock insight into this route of communication between microbe and host.