AGA Small Intestinal Microbiome: An Underappreciated Driver of Gastrointestinal Disease and Novel Therapeutic Target

Society: AGA

Microbiome science in the gut has focused on the study of colonic, and more frequently, fecal communities. While the upper gastrointestinal tract has significantly lower bacterial density than the colon, it still harbors a dynamic microbial community. Comparatively little is known about microbiota structure and function in the oral cavity, gastric and small intestine. This is counterintuitive as the upper GI tract is the place for the establishment of oral tolerance, a main site for carbohydrate, lipid and protein digestion and metabolism. This process releases active metabolites that will directly impact host tissues. Indeed, emerging studies in model diseases such as celiac disease and environmental enteropathy, that primarily affect the small intestine, have demonstrated precise diet-opportunistic pathogen interactions that may affect disease onset and severity. More importantly, understanding of these mechanisms can inform the development of targeted microbial therapeutics, that could also benefit other inflammatory disorders.