Characterisation of MRGPRX2 mast cells in irritable bowel syndrome.

Background: Mast cell activation is an important driver of abdominal pain in irritable bowel syndrome (IBS). While evidence supports the role of IgE-mediated mast cell activation in visceral pain development in IBS, the role of pseudoallergic MRGPRX2-mediated mast cell activation in this process remains unknown.

Objective: We investigated whether MRGPRX2-mediated mast cell activation plays a role in abdominal pain development in patients with IBS.

Psychological stress-induced local immune response to food antigens increases pain signaling across the gut in mice.

Background & Aims: We recently showed that a bacterial infection can break oral tolerance to food and lead to IgE-dependent mast cell activation and food-induced abdominal pain, which could constitute an important pathogenic mechanism in post-infectious irritable bowel syndrome (IBS). Here, we investigated whether similar immune mechanisms in response to psychological stress lead to food-evoked pain signaling, and thus potentially explain the pathophysiology in a larger group of patients with IBS.

Methods: Mice were exposed to ovalbumin (OVA) during water avoidance stress (WAS) and re-exposed to OVA five weeks later.

Fecal Proteolytic Bacteria and Staphylococcal Superantigens Are Associated With Abdominal Pain Severity in Irritable Bowel Syndrome.

Introduction: Changes in the composition of the gut microbiota have been associated with the development of irritable bowel syndrome (IBS). However, to what extent specific bacterial species relate to clinical symptoms remains poorly characterized. We investigated the clinical relevance of bacterial species linked with increased proteolytic activity, histamine production, and superantigen (SAg) production in patients with IBS.

Dedicated macrophages organize and maintain the enteric nervous system.

Correct development and maturation of the enteric nervous system (ENS) is critical for survival. At birth, the ENS is immature and requires considerable refinement to exert its functions in adulthood. Here we demonstrate that resident macrophages of the muscularis externa (MMϕ) refine the ENS early in life by pruning synapses and phagocytosing enteric neurons.

Local immune response to food antigens drives meal-induced abdominal pain.

Up to 20% of people worldwide develop gastrointestinal symptoms following a meal, leading to decreased quality of life, substantial morbidity and high medical costs. Although the interest of both the scientific and lay communities in this issue has increased markedly in recent years, with the worldwide introduction of gluten-free and other diets, the underlying mechanisms of food-induced abdominal complaints remain largely unknown. Here we show that a bacterial infection and bacterial toxins can trigger an immune response that leads to the production of dietary-antigen-specific IgE antibodies in mice, which are limited to the intestine.