8th Annual BMRP Investigator Meeting - Abstract
The Gut Flora under Environmental Aspects: Metagenomic Alterations of the Intestinal Microbiome Associated with Lifestyle and their Role in the Pathogenesis of Inflammatory Bowel Diseases (IBD)
Stephan Ott
University Hospital Schleswig-Holstein (Germany)
Introduction: Epidemiologic studies point to the critical role of environmental factors in the pathogenesis of chronic inflammatory barrier diseases, e.g., IBD or asthma. Lifestyle factors, such as nutrition and hygiene habits, could account for the raising incidence of these disorders in industrialized countries (hygiene hypothesis).
Aims: The aim of this study is to compare the composition of the intestinal microbiota of rural areas with low incidence of civilization diseases (representing the “ancient” lifestyle of the pre-industrialization period) and a region in an urban area, which over decades is influenced by multiple environmental factors (“modern” lifestyle).
Methods: Healthy individuals and IBD patients from Germany, India, and Lithuania (n=90) have been recruited and investigated in groups (healthy vs. IBD, Lithuania vs. India vs. Germany). Biopsy material is used as basic material to investigate alterations of the mucosa-associated microbiota. State-of-the-art metagenomic techniques, such as large-scale 16S rDNA clone libraries and chip technology, which have enriched the repertoire of molecular microbiology in the description of complex ecosystems, will be employed to give a detailed description of the intestinal diversity in the different groups. Modern statistical methods are employed to analyze and compare diversity and to estimate markers of the quality and appropriateness of clone libraries.
Preliminary Results: Two clone libraries (with a total number of > 1.500 sequenced clones) have been analyzed and showed significant qualitative differences in the composition of bacterial species and groups. The overall richness of bacterial operational taxonomic units (OTUs) was significantly higher in the Lithuanian population in contrast to German individuals (n=193 vs. 133). Bacterial phyla showed significant increase in the Lithuanian group of Firmicutes (50.5 vs. 40.6%) and Proteobacteria (16.5 vs. 11.9%), in the German population of Bacteriodetes (25.7 vs. 41.4%, all p<0.05).
Conclusions: The data will evaluate our previous hypothesis of dysbiosis with a loss of diversity and a shift of bacterial populations towards a more toxic profile (e.g. increase in diversity of Bacteroides sp.) as a pathogenetic principle in the growing incidence of chronic inflammatory disorders in industrialized countries. The understanding of the behavior of complex microbial systems under environmental selection/pressure may open new ways for prevention and selective manipulation of the intestinal microbiota towards a better health, e.g., by design of customized pre- or pro-biotic formulations or nutritional products.