Host-microbiome interactions in health and digestive diseases

Ulcerative colitis (UC) and Crohn’s disease (CD) are chronic inflammatory bowel diseases (IBD). Mounting evidence suggests that IBD is a complex disease that results from interplay between genetic, immunological and environmental factors. Genetic studies have identified >200 single nucleotide polymorfisms (SNP) linked to IBD. Nevertheless, genetic findings cannot explain the rapid increase in incidence in Asian countries and large cities of Latin-America. The role of intestinal microbiota should not be underestimated and changes in the composition of gut microbiota, also known as dysbiosis, have shown to play a key role in the pathogenesis of IBD. Our group already characterized intestinal dysbiosis in UC and CD, and showed a reduction of butyrate-producing bacteria. Presently, we are describing the associations between intestinal microbiota and SNPs linked to IBD. IBD is associated with primary sclerosing cholangitis (PSC). About 70% of patients with PSC have some form of IBD. Presently, there is no effective medical treatment for PSC and 16-40% patients need liver transplantation. The exact cause remains unknown and the role of bacteria in PSC is poorly understood. Recently, we have also characterized dysbiosis in PSC, wich includes increased Enterococcus, Lactobacillus and Fusobacterium. We will also perform immunological studies in order to better understand the interplay between gut microbiota and the immune system of the host. Finally, as diet has probably the strongest influence on gut microbiota, our third aim is to investigate the influence of dietary changes on the composition of gut microbiota in IBD. Food influence on the Intestinal microbioTa (FIT) is a dietary intervention study with focus on intestinal microbiota changes after a dietary intervention. Twenty-nine healthy volunteers have already finished the FIT diet. Fecal calprotectin was significantly decreased after 1 month of FIT diet. Presently, we are including patients with ulcerative colitis for the FIT study.status: publishe