Irritable bowel syndrome: a gut microbiota-related disorder?

Abstract

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal (GI) disorders. Despite its prevalence, the pathophysiology of IBS is not well understood although multiple peripheral and central factors are implicated. Recent studies suggest a role for alterations in gut microbiota in IBS. Significant advances in next-generation sequencing technology and bioinformatics and the declining cost have now allowed us to better investigate the role of gut microbiota in IBS. In the following review, we propose gut microbiota as a unifying factor in the pathophysiology of IBS. We first describe how gut microbiota can be influenced by factors predisposing individuals to IBS such as host genetics, stress, diet, antibiotics, and early life experiences. We then highlight the known effects of gut microbiota on mechanisms implicated in the pathophysiology of IBS including disrupted gut brain axis (GBA), visceral hypersensitivity (VH), altered GI motility, epithelial barrier dysfunction, and immune activation. While there are several gaps in the field that preclude us from connecting the dots to establish causation, we hope this overview will allow us to identify and fill in the voids.

Keywords: GBA; IBS; VH; gut brain axis; gut microbiota; irritable bowel syndrome; visceral hypersensitivity.

Fig. 1.

Gut microbiota is a common denominator in pathophysiology of irritable bowel syndrome (IBS). Gut microbiota modulates pathophysiological mechanisms underlying IBS such as gastrointestinal motility and sensation, gut brain axis, immune activation, and intestinal barrier function. Gut microbiota composition is affected by risk factors underlying IBS such as host genetics, stress, diet, antibiotics usage and early childhood experience. 5-HT, 5-hydroxytryptamine (serotonin); TLR, Toll-like receptor; ZO, zonula occludens.