GI highlights from the literature

Abstract

► Yilmaz B, Juillerat P, Oyas O, et al. Microbial network disturbances in relapsing refractory Crohn’s disease. Nature Medicine 2019 25:323–326 Patients with inflammatory bowel disease (IBD) display variability in disease severity, distribution and response to treatment. This cannot be accounted for by host genetic susceptibility. There is focus on mapping environmental exposures, including the microbiota in order to predict these disease behaviours. However, to achieve this, it is necessary to analyse large well-phenotyped cohorts that are followed prospectively over many years. While there are such initiatives, many are in their infancy and will take time for data to become available. Here, the authors studied two Swiss long-term IBD cohorts and defined distinct microbial networks containing taxa belonging to Lachnospiraceae and Ruminococcaceae that were associated with relapsing disease and also poor treatment outcome. They defined these taxa as Cluster CDA and through predictive function analysis suggested that these taxa may increase intraluminal oxygen, thus allowing facultative pathogens, such as Escherichia coli, to bloom. The study also identified a cluster of taxa including shortchain fatty acid producing strains that could distinguish between Crohn disease (CD) and ulcerative colitis (UC) and were predictive of a quiescent disease course and a healthier lifestyle. In addition to the significant original dataset generated, they also conducted a meta-analysis of the currently published IBD microbiome studies. The authors concluded their study by predicting that subsequent attempts to manipulate the gut microbiota in patients with IBD would be most successful if targeted against defects in Cluster CDA.