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Background: IBS affects a large number of children throughout the world and is thought to be the result of disturbed neuroimmune function along with the brain–gut axis. Although the underlying pathophysiologic mechanisms are not clear, the role of low‐grade inflammation and mucosal immune activation in IBS symptom generation has become evident also in subsets of pediatric patients. Animal models provided meaningful insight in the causal relationship between abnormal mucosal immune activation and changes in gastrointestinal (GI) sensory‐motor function. Likewise, the development of long‐standing GI symptoms fulfilling the current criteria for functional GI disorders after infection gastroenteritis and in patients with IBD or celiac disease in remission further supports this hypothesis. Immune activation, its impact on gut sensory‐motor function, and potential implications for symptom generation emerged in both children and adults with IBS. Purpose: The aim of this review is to summarize the main evidence on the presence of low‐grade inflammation and immune activation in children with IBS, its possible role in symptom generation, and its potential implication for new therapeutic strategies. [ABSTRACT FROM AUTHOR]

Background: Gastrointestinal food allergy (GIFA) occurs in 2 to 4 % of children, the majority of whom are infants (<1 year of age). Although endoscopy is considered the gold standard for diagnosing GIFA, it is invasive and requires general anaesthesia. Therefore, we aimed to investigate whether in infants with GIFA, gastrointestinal symptoms predict histological findings in order to help optimise the care pathway for such patients. Methods: All infants <1 year of age over a 20 year period who underwent an endoscopic procedure gastroscopy or colonoscopy for GIFA were evaluated for the study. Symptoms at presentation were reviewed and compared with mucosal biopsy histological findings, which were initially broadly classified for study purposes as "Normal" or "Abnormal" (defined as the presence of any mucosal inflammation by the reporting pathologist at the time of biopsy). Results: Of a total of 1319 cases, 544 fitted the inclusion criteria. 62 % of mucosal biopsy series in this group were reported as abnormal. Infants presenting with diarrhoea, rectal (PR) bleeding, irritability and urticaria in any combination had a probability >85 % (OR > 5.67) of having abnormal histological findings compared to those without. Those with isolated PR bleeding or diarrhoea were associated with 74 % and 68 % probability (OR: 2.85 and 2.13) of an abnormal biopsy, respectively. Conversely, children presenting with faltering growth or reflux/vomiting showed any abnormal mucosal histology in only 50.8 % and 45.3 % (OR: 1.04 and 0.82) respectively. Conclusions: Food allergy may occur in very young children and is difficult to diagnose. Since endoscopy in infants has significant risks, stratification of decision-making may be aided by symptoms. At least one mucosal biopsy demonstrated an abnormal finding in around half of cases in this selected population. Infants presenting with diarrhoea, PR bleeding, urticaria and irritability are most likely to demonstrate abnormal histological findings. [ABSTRACT FROM AUTHOR]

OBJECTIVES:Food allergy is thought to trigger functional constipation in children but the underlying mechanisms are still unknown. Mast cells (MCs) and their relationship with nerve fibers (NFs) in the rectal mucosa, as well as anorectal motility, were studied in children with refractory chronic constipation before and after an elimination diet for cow's milk, egg, and soy proteins.METHODS:Thirty-three children (range: 1–10.8 years) underwent anorectal manometry and suction rectal biopsy before and after 8 weeks of oligoantigenic diet. MCs and NFs were identified immunohistochemically. Quantification of MCs (%MC/area) and MCs within 10 μm of NFs (%MC-NF/area) was performed by computer-assisted analysis.RESULTS:Eighteen children responded to the diet (R-group) and fifteen did not (the NR-group). At baseline there was a significant difference in anal resting pressure (ARP; mm Hg), percentage of relaxation (%R), and residual pressure (RP; mm Hg) of anal canal during rectal distension between the R-group (66±4.1, 84.3±2.8, 10.4±2.3, respectively) and the NR-group (49±5, 92.2±1.7, 4.8±1.7, respectively; P<0.05). After the diet, significant changes in ARP, RP, and %R were observed only in the R-group (44±3.7, 93.7±1.5, 3.8±1.2, respectively; P<0.05). At baseline, the R-group showed an increase in %MC/area (8.3±0.7) and %MC-NF/area (5.2±2.6) with respect to the NR-group (5.1±0.5 and 2.3±0.4, respectively; P<0.05). After the diet, only the R-group showed a significant reduction of %MC/area and %MC-NF/area (4.4±0.5 and 2.2±0.4, respectively; P<0.001). Both ARP and RP significantly correlated with %MC/area and %MC-NF/area; %R showed a significant inverse correlation with both %MC/area and %MC-NF/area.CONCLUSIONS:In children with food allergy-related chronic constipation, an increase in both rectal MC density and spatial interactions between MCs and NFs correlates with anal motor abnormalities. These variables are significantly affected by the diet.Am J Gastroenterol 2009; 104:454–463; doi:10.1038/ajg.2008.109; published online 20 January 2009 [ABSTRACT FROM AUTHOR]