Microbiota-gut-brain axis and its affect inflammatory bowel disease: Pathophysiological concepts and insights for clinicians

Abstract

Despite the bi-directional interaction between gut microbiota and the brain not being fully understood, there is increasing evidence arising from animal and human studies that show how this intricate relationship may facilitate inflammatory bowel disease (IBD) pathogenesis, with consequent important implications on the possibility to improve the clinical outcomes of the diseases themselves, by acting on the different components of this system, mainly by modifying the microbiota. With the emergence of precision medicine, strategies in which patients with IBD might be categorized other than for standard gut symptom complexes could offer the opportunity to tailor therapies to individual patients. The aim of this narrative review is to elaborate on the concept of the gut-brain-microbiota axis and its clinical significance regarding IBD on the basis of recent scientific literature, and finally to focus on pharmacological therapies that could allow us to favorably modify the function of this complex system.

Keywords: Gut-brain axis; Inflammatory bowel disease; Irritable bowel syndrome; Therapy.

Figure 1

The main actors in the gut–brain-microbiota axis. The gut-brain-microbiota axis is defined as a two-way communication system that allows intestinal microbes to communicate with the brain and vice versa. The multiple inter-related structural networks of the central nervous system regulates autonomic nervous system input that alter gut microbial composition and function indirectly by modulating the microbial environment in the gut, and by affecting also the immune response. On the other hand, the gut microbiota can interact with the brain indirectly via gut-derived metabolites by acting on afferent vagal and/or spinal nerve endings, or directly via microbe-generated signals which act on enteroendocrine cells. Furthermore, the neuroendocrine signaling network mediated by the hypothalamic-pituitary-adrenal) axis, which is activated by the integrative reactions of specific centers in the central nervous system, represents a central integrative system mandatory for the successful physiological adaptation of our organism to different stressors.