Anti-inflammatory properties of Faecalibacterium prausnitzii in the absence and presence of cigarette smoke using a novel epithelium-gut microbe coculture system

Background: Inflammatory bowel disease (IBD) is characterised bya recurrent inflammation of the gut epithelium. Although the pathogenesis is still largely unknown, different factors contribute to the disease, including genetic and environmental factors. Cigarette smoking is the most-studied environmental factor associated with IBD. Moreover, gut microbiota play a central role in the pathogenes is ofIBD. In this study we aimed to investigate the effects of host-microbe interactions on the gut epithelium with a potentially beneficial bacterium,Faecalibacterium prausnitzii, in a recently established coculture system for anaerobic bacteria and oxygen-requiring humanintestinal epithelial (Caco-2) cells. Hence, we analysed the effect of an inflammatory cytokine (TNF-α) and cigarette smoke extract(CSE) on the growth of F. prausnitzii and expression of inflammatory markers in Caco-2 cells.

Methods: F. prausnitzii and human Caco-2 cells were cocultured in the ‘Human oxygen Bacteria anaerobic’ (HoxBan) system and exposed to TNF-α and/or CSE. Bacterial growth was monitored visually, and expression of the inflammatory marker iNOS and oxidative stress marker HO-1 were determined by quantitative PCR.

Results: F. prausnitzii grew well in the HoxBan coculturing system in the presence of TNF-α or with added CSE, with no observable difference to control conditions. F. prausnitzii strongly suppressed iNOS expression, both in TNF-α treated and control Caco-2 cells.CSE did not induce iNOS or HO-1 expression in Caco-2 cells,but F. prausnitzii strongly suppressed iNOS expression both in the absence and presence of CSE, with similar trends observed for HO-1.

Conclusions: We conclude that F. prausnitzii produces potent antiinflammatoryfactors, which is independent of cigarette smoking.F. prausnitzii and its secreted products are therefore interesting targetsfor the treatment of intestinal inflammation, in particular forIBD