Stress, Intestinal Inflammation, and Irritable Bowel Syndrome

Introduction

Irritable bowel syndrome (IBS) is a chronic heterogeneous disorder characterized by recurrent abdominal pain and distorted bowel habits afflicting 10%–20% of adults worldwide. In fact, IBS stands as a major cause of medical consultation and a leading diagnosis among gastroenterological outpatients. Unfortunately, there is neither a unifying theory for IBS origin and nature nor specific diagnostic markers. In addition, the lack of therapeutic options providing satisfactory long-standing clinical remission accounts for the notable impairment in the quality of life of those affected and for the increasing direct medical expenses and indirect costs.

Abstract

Irritable bowel syndrome (IBS) is a highly prevalent disorder that comprises a heterogeneous group of patients suffering from chronic and recurrent abdominal pain usually associated with visceral hypersensitivity and altered bowel habit. The etiology of IBS is considered multifactorial, being psychosocial events especially life stress and gastrointestinal infections, key players in the onset, persistence, and severity of clinical manifestations. Furthermore, the common presence of low-grade inflammation and immune activation in the intestinal mucosa of certain IBS subgroups challenge the traditional assumption of IBS as a prototypic gut functional disorder and provide a plausible hypothesis linking stress and infections to IBS development. The breakdown of intestinal epithelial barrier's surveillance may represent a leading event in such a connection, as converging observations link the onset and severity of abdominal pain and visceral hypersensitivity to structural and functional abnormalities of the mucosal barrier. Consequently, intestinal barrier dysfunction might facilitate unfettered penetration of food and bacterial antigens across the epithelium to stimulate disruptive immunological responses favoring the development of mucosal inflammation. In this review, we summarize the most relevant evidences of stress-induced intestinal inflammation and discuss the most important mediators and mechanisms that have been involved.

Keywords

Stress, irritable bowel syndrome, inflammation, intestinal barrier, mast cells, CRH/CRF