Digestive Disease Week 2016 was held in San Diego during the month of May, where the role of the intestinal microbiota in health and disease continues to be a major topic in gastroenterology. This year, the functional role of the microbiota was especially highlighted in both clinical and basic science sessions, where there was a focus on microbiota transfer studies in germ-free mice, on metabolomics and metagenomics, and on modulating the microbiota to treat diseases.
While the microbiota has been implicated in a number of inflammatory diseases, such as IBD, celiac disease, and obesity, causality has been difficult to prove. There were a number of sessions at DDW that highlighted the importance of using gnotobiotic and germ-free mice to shed light on the functional role of the microbiota in disease pathogenesis. For example, Justin McCarville, a PhD candidate from McMaster University, showed that microbiota from celiac disease patients can induce innate immune activation in mice, independently of gluten exposure. This mechanism may promote celiac disease in a genetically susceptible host. Other sessions at DDW highlighted the importance of using these “humanized” animal models to evaluate mechanisms as well as the role of specific bacterial metabolites, such as those derived from SCFA and bile acids, in obesity, IBS, and IBD. While subject to all limitations of mouse modelling experimentation, gnotobiotic tools may bring much needed knowledge about functionality in microbiome research.
The use of metagenomics was another widely discussed topic at this year’s DDW. Rob Knight, from the University of California, discussed the use of metagenomics to classify inflammatory bowel disease patients and healthy controls, and stressed the importance of longitudinal studies to understand the changes in microbiota over time, as well as the importance of genome mining to understand how microbes and host collaborate to produce metabolic and immunologic readouts.
Given the potential role of the microbiota in disease pathogenesis, a number of microbiota-modulating strategies to treat diseases were presented. These included dietary interventions, probiotics, antibiotics, and fecal microbiota transplantation (FMT). FMT was a hot topic at this year’s DDW; presenters covered data on its effectiveness for recurrent C. diff infection in adults. On the other hand, data on FMT to treat IBD are promising, but still preliminary. The future of FMT was a major topic of discussion; the consensus from experts was that researchers need to uncover the characteristics of both donors and patients that lead to successful FMTs, and to conduct longer studies to evaluate long-term risks and side effects.