ABSTRACT
BACKGROUND: Neuroimmune interactions and inflammation have been proposed as factors involved in sensory-motor dysfunction and symptom generation in adult irritable bowel syndrome (IBS) patients. In children with IBS and healthy controls, we measured ileocolonic mast cell infiltration and fecal calprotectin and evaluated the relationships between these parameters and abdominal pain symptoms and stooling pattern. METHODS: Irritable bowel syndrome patients diagnosed according to Pediatric Rome III criteria and healthy controls kept a 2-week pain/stooling diary. Ileocolonic mucosal mast cells (MC) and MC in close proximity to nerve fibers (MC-NF) were identified immunohistochemically and quantified. Fecal calprotectin concentration was measured. KEY RESULTS: 21 IBS patients and 10 controls were enrolled. The MC-NF count was significantly higher in the ileum (p = 0.01), right colon (p = 0.04), and left colon (p < 0.001) of IBS patients compared with controls. No differences in fecal calprotectin concentration were noted. Abdominal pain intensity score correlated with ileal MC count (r(s) = 0.47, p = 0.030) and right colon MC-NF count (r(s) = 0.52, p = 0.015). In addition, children with IBS with >3 abdominal pain episodes/week had greater ileal (p = 0.002) and right colonic (p = 0.01) MC counts and greater ileal (p = 0.05) and right colonic (p = 0.016) MC-NF counts than children with less frequent pain. No relationship was found between MC and MC-NF and fecal calprotectin or stooling pattern. CONCLUSIONS & INFERENCES: Mast cells-nerve fibers counts are increased in the ileocolonic mucosa of children with IBS. Mast cells and MC-NF counts are related to the intensity and frequency of abdominal pain.
Subject(s)
Abdominal Pain/etiology , Irritable Bowel Syndrome/etiology , Neuroimmunomodulation , Abdominal Pain/immunology , Abdominal Pain/pathology , Adolescent , Child , Child, Preschool , Female , Humans , Intestines/pathology , Irritable Bowel Syndrome/diagnosis , Irritable Bowel Syndrome/immunology , Irritable Bowel Syndrome/pathology , Leukocyte L1 Antigen Complex/analysis , Male , Mast Cells/pathology , Nerve Fibers/pathologyABSTRACT
BACKGROUND: Mediators released in the mucosal milieu have been suggested to be involved in visceral hypersensitivity and abdominal pain in patients with irritable bowel syndrome (IBS). However, their impact on myenteric neurons remains unsettled. METHODS: Mucosal biopsies were obtained from the descending colon of patients with IBS and controls. Mucosal mast cells were identified immunohistochemically. The impact of spontaneously released mucosal mediators on guinea pig electrically stimulated longitudinal muscle myenteric plexus (LMMP) preparations was assessed in vitro by means of selective receptor antagonists and inhibitors. KEY RESULTS: Patients with IBS showed an increased mast cell count compared with controls. Application of mucosal mediators of IBS to LMMPs potentiated cholinergic twitch contractions, an effect directly correlated with mast cell counts. Enhanced contractions were inhibited by 50.3% with the prostaglandin D2 antagonist BW A868C, by 31.3% and 39% with the TRPV1 antagonists capsazepine and HC-030031, respectively, and by 60.5% with purinergic P2X antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Conversely, the serotonin1-4, histamine1-3, tachykinin1-3 receptor blockade, and serine protease inhibition had no significant effect. CONCLUSIONS & INFERENCES: Colonic mucosal mediators from patients with IBS excite myenteric cholinergic motor neurons. These effects were correlated with mast cell counts and mediated by activation of prostanoid receptors, TRPV1, and P2X receptors. These results support the role of mucosal inflammatory mediators and mast cell activation in altered motor function of IBS.
