The Influence of Commensal Bacteria on the Gut-Brain Axis: Implications for Understanding and Treating Functional GI Disorders

The gut-brain axis has been described as a bi-directional neuro-humeral communication system and is implicated in the pathogenesis of functional gastrointestinal disorders such as irritable bowel syndrome (IBS). Recent work has shown that a subset of patients with IBS show evidence of low grade immune activation and inflammation in the colonic mucosa. This review focuses on the role of the intestinal microbiota and discusses the interrelationship between the intestinal microbiota and maintaining of low grade inflammation, gut dysfunction or behavioral changes using murine models and clinical studies. The findings in murine models show that perturbation of gut flora is a putative mechanism for gut dysfunction in IBS and together with clinical studies they indicate that dysbiosis in patients with IBS psychiatric co-morbidity.