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DOP016. Smoking cessation alters intestinal microbiota - further insights from quantitative investigations on human faecal samples using FISH and qPCR

L. Biedermann1, K. Brülisauer2, J. Zeitz1, P. Frei1,3, M. Scharl1, S.R. Vavricka1,4, M. Fried1, M.J. Loessner2, G. Rogler1, M. Schuppler2, 1University Hospital Zurich, Gastroenterology & Hepatology, Zurich, Switzerland, 2ETH Zurich, Institute of Food, Nutrition and Health, Zurich, Switzerland, 3Seespital Horgen, Gastroenterology & Hepatology, Horgen, Switzerland, 4Hospital Triemli, Gastroenterology & Hepatology, Zurich, Switzerland

Background

An increasing body of evidence indicates a pathogenic role of the intestinal microbiota in various disease states, including inflammatory bowel diseases. In both CD and UC numerous specific alterations in microbial composition have been described. In the last decades, several factors modulating intestinal microbial composition could be identified. We recently reported that the intestinal microbiota is altered after smoking cessation in humans by means of 454 pyrosequencing. In this study we aimed to conduct further quantitative microbial analyses with a special focus on microorganisms, which previously have been associated to dysbiosis in IBD.

Methods

Stool samples of healthy smoking human subjects undergoing controlled smoking cessation were analysed and compared to two control groups, on-going smoking and non-smoking subjects. Fluorescence in situ hybridization (FISH) and quantitative real-time PCR were used to quantify different bacterial phyla.

Results

Intestinal microbiota composition was substantially altered after smoking cessation showing an increase of key representatives from the phyla Firmicutes (C. coccoides–E. rectale and C. leptum subgroup) and Actinobacteria (HGC bacteria and Bifidobacteria) as well as a decrease of members of Bacteroidetes (Prevotella spp. and Bacteroides spp.) and Proteobacteria (β- and γ-Proteobacteria).

As far as Bifidobacteria and E. rectale - the latter as well as B. adolescentis and B. bifidum have previously been shown to be decreased in CD [1–3] - a lower abundance was observed in the smoking control groups with an increase after smoking cessation (percentage of bacterial counts: 0.95% vs. 2.31%, p < 0.01 and 8.08% vs. 13.98%, p < 0.01 for Bif. and E. rect. pre vs. post smoking cessation, respectively). In contrast, members of Bacteroides/Prevotella group - previously shown to be decreased in UC [4,5] - were less abundant in non-smokers and in the intervention group after smoking cessation (percentage of bacterial counts: 7.02% vs. 4.1%, p = 0.01, pre- vs. post-smoking cessation, respectively).

Conclusion

Using quantitative microbial approaches we confirmed our previous finding derived by pyrosequencing, that intestinal microbiota composition in humans is markedly influenced by smoking status. More importantly, several observed microbial alterations after smoking cessation are congruent with regard to previously described different microbial hallmarks of dysbiosis in CD and UC and the divergent effect of smoking status on the course of both disease entities.

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