OP36 Investigating the role of bioactives produced by gut bacteria to modulate immune response in inflammatory bowel disease
R. Giri1,2, K. Shamsunnahar3, A. Salim3, R. Capon3, M. Morrison4, P. O Cuiv4, J. Begun1,2
1Faculty of Medicine, The University of Queensland, Brisbane, Australia, 2Mater Research Institute, The University of Queensland, Brisbane, Australia, 3The Institute for Molecular Biosciences, The University of Queensland, Brisbane, Australia, 4The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, Australia
Background
inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract. Although the pathogenesis of IBD is not fully understood, it is believed to result from the interaction between various genetic and environmental factors, including the microbiome, resulting in inappropriate gut inflammation. Under homeostatic conditions, the gut immune system exists in a tolerogenic state with the microbiota. However, microbial dysbiosis and an imbalance of pro- and anti-inflammatory cytokines in the gut characterise IBD and recently faecal microbiota transplantation studies have demonstrated that manipulation of the microbiome can induce remission. In this study, the ability of bioactives produced from single species of anaerobic gut bacteria cultured from healthy human faecal samples to modulate NF-kB activity was investigated, their biochemical properties were assessed and their ability to alleviate colitis was also investigated.
Methods
The NF-κB suppressive effects of culture supernatants (CSs) from 23 different isolates were tested on colonic epithelial cell lines. Suppressive CSs were also tested on human-derived colonic organoids from IBD patients and healthy controls and IL-8 expression was measured. Furthermore, CS from AHG0001 strain was also tested in spontaneous colitis model
Results
LS174T and Caco-2 reporter cells stimulated with TNFα and IL-1β respectively, resulted in NF-κB activation. Of the 23 isolates screened, CS from five isolates significantly suppressed NF-κB activation. The selected CSs also suppressed IL-8 secretion in PBMCs and gut organoids from both UC and CD patients, as well as healthy controls, with notable individual variation. Rectal gavage of CS from AHG0001 also reduced disease activity, improved histologic inflammation and reduced the pro-inflammatory gene expression in Winnie mice. Furthermore, a potent small molecule (IC50 = 3 nM) produced by AHG0001 was also identified through bioassay-guided solvent extractions and filtrations, followed by UPLC-QTOF and comparative metabolomics.
Conclusion
Our anaerobic culturing and NF-κB reporter assay system allows for the rapid identification of bacteria producing immunomodulatory bioactives, which could lead to the future development of novel therapeutics. Our