Eosinophils and mast cells as therapeutic targets in pediatric functional dyspepsia

Physiological mechanisms of unexplained (functional) gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) encompass a range of complex conditions with similar clinical characteristics and no overt pathology. Recent recognition of sub-clinical pathologies in FGIDs, in conjunction with physiological and biochemical abnormalities including increased intestinal permeability, microbial profile alterations, differences in metabolites and extra-intestinal manifestations of disease, call into question the designation of these conditions as 'functional'. This is despite significant heterogeneity in both symptom profile and specifics of reported physiological abnormalities hampering efforts to determine defined mechanisms that drive onset and chronicity of symptoms. Instead, the literature demonstrates these conditions are disorders of homeostatic imbalance, with disruptions in both host and microbial function and metabolism. This imbalance is also associated with extraintestinal abnormalities including psychological comorbidities and fatigue that may be a consequence of gastrointestinal disruption. Given the exploitation of such abnormalities will be crucial for improved therapeutic selection, an enhanced understanding of the relationship between alterations in function of the gastrointestinal tract and the response of the immune system is of interest in identifying mechanisms that drive FGID onset and chronicity. Considerations for future research should include the role of sex hormones in regulating physiological functions and treatment responses in patients, as well as the importance of high-level phenotyping of clinical, immune, microbial and physiological parameters in study cohorts. There is opportunity to examine the functional contribution of the microbiota and associated metabolites as a source of mechanistic insight and targets for therapeutic modulation.

Characterizing clinical features and location-specific gene expression profiles associated with pain burden in children with functional dyspepsia

BACKGROUND

In children with functional dyspepsia (FD), genes involved in pain modulation may be differentially expressed contributing to chronic pain.

METHODS

Children with suspected FD (cases) and known eosinophilic esophagitis (controls) undergoing esophagogastroduodenoscopy completed the Rome IV Diagnostic, Pain Burden and Frequency Severity-Duration questionnaires. Two antral and two duodenal biopsies were collected and relative fold differences in gene expression for 84 pain-associated genes compared to pain-free controls were calculated.

RESULTS

Sixty-six subjects with FD (postprandial distress syndrome = 34, epigastric pain syndrome = 7, both = 25; 65% female; mean age 13.7 years) and 13 pain-free controls (8% female; mean age 12.7) were studied. There were no significant differences in antral and duodenal eosinophilic counts or distribution between the pain and pain-free groups. Pain severity and burden did not differ significantly between FD subgroups and neither measure significantly correlated with eosinophil counts in the antrum or duodenum. Analysis of 47 antral and 39 duodenal biospecimens revealed 5 candidate genes significantly associated with pain burden: antral EDN1, PTGES3 and duodenal HTR1A, P2Y1, SCN3A (p < 0.01). Subsequent stringent statistical analysis comparing those with significant pain versus no pain revealed antral PTGES3 and duodenal SCN3A were the highest priority candidate genes (p < 0.001).

CONCLUSIONS

Pain burden in pediatric FD may be linked to antral EDN1, PTGES3 and duodenal HTR1A, P2Y1, SCN3A differential expression. These genes are known to be involved in pain conduction, modulation, and neurotransmission, suggesting potential therapeutic targets for managing pain in FD.

Rumination Syndrome in Children and Adolescents: A Mini Review

Introduction: Rumination syndrome involves recurrent regurgitation of food and is believed to be underdiagnosed with patients experiencing long delays in diagnosis. It can be associated with significant social consequences, high rates of school absenteeism, and medical complications such as weight loss. The primary aims of the current review are to assess the literature regarding prevalence, pathophysiology, and treatment outcomes with a focus on neurotypical children and adolescents. Results: Population studies in children/adolescents, 5 years of age or older, range from 0 to 5.1%. There are fewer studies in clinical settings, but the prevalence appears to be higher in patients with other gastrointestinal symptoms, particularly chronic vomiting. While physiologic changes that occur during a rumination episode are well-described, the underlying cause is less well-defined. In general, rumination appears to have similarities to other functional gastrointestinal disorders including dysmotility, possibly inflammation, and an interaction with psychologic function. While diaphragmatic breathing is considered the mainstay of treatment, pediatric data demonstrating efficacy is lacking, especially as an isolated treatment. Conclusion: Pediatric rumination syndrome remains greatly understudied, particularly regarding treatment. There is a need to better define prevalence in both the primary care and subspecialty clinical settings, especially in patients presenting with vomiting or apparent gastroesophageal reflux. There is a need to determine whether treatment of co-morbid conditions results in improvement of rumination. Diaphragmatic breathing needs to be studied and compared to other competing responses.

An Update on the Assessment and Management of Pediatric Abdominal Pain

Chronic abdominal pain is very common in children and adolescent and results in high personal and social costs. Most youth with chronic abdominal pain fulfill criteria for a functional abdominal pain disorder (FAPD) as defined by Rome criteria. These are complex conditions with a wide array of biological, psychological, and social factors contributing to the experience of pain. The purpose of the current review is to provide an overview of the pathophysiology of FAPDs and an up-to-date summary of the literature related to FAPDs in children and adolescents, with additional focus on several areas (eg, diet and probiotics) where patients and families frequently have questions or implement self-directed care. We also provide an approach to the assessment and treatment of pediatric FAPDs focusing on the robust literature regarding psychological interventions and much sparser literature regarding medication treatment.

Update on the Role of Allergy in Pediatric Functional Abdominal Pain Disorders: A Clinical Perspective

Both functional abdominal pain disorders (FAPDs) and food allergies are relatively common in children and adolescents, and most studies report an association between FAPDs and allergic conditions. FAPDs share pathophysiologic processes with allergies, including both immune and psychological processes interacting with the microbiome. No conclusive data are implicating IgE-mediated reactions to foods in FAPDs; however, there may be patients who have IgE reactions localized to the gastrointestinal mucosa without systemic symptoms that are not identified by common tests. In FAPDs, the data appears stronger for aeroallergens than for foods. It also remains possible that food antigens initiate an IgG reaction that promotes mast cell activation. If a food allergen is identified, the management involves eliminating the specific food from the diet. In the absence of systemic allergic symptoms or oral allergy syndrome, it appears unlikely that allergic triggers for FAPDs can be reliably identified by standard testing. Medications used to blunt allergic reactions or symptomatically treat allergic reactions may be useful in FAPDs. The purpose of the current manuscript is to review the current literature regarding the role of allergy in FAPDs from a clinical perspective, including how allergy may fit in the current model of FAPDs.

A cross-sectional study of nausea in functional abdominal pain: relation to mucosal mast cells and psychological functioning

Background

Nausea is a common symptom in youth with chronic abdominal pain. The aims of the current study were to assess: 1) the frequency of nausea in patients with functional dyspepsia (FD) and irritable bowel syndrome (IBS), respectively, as defined by Rome IV criteria; and, 2) relationships between nausea and mucosal inflammation as defined by antral and duodenal eosinophil and mast cell densities. A secondary aim was to assess relationships between nausea and other gastrointestinal symptoms, non-gastrointestinal somatic symptoms, and psychological dysfunction.

Methods

Records from patients with pain associated functional gastrointestinal disorders were retrospectively reviewed for gastrointestinal and somatic symptoms and anxiety, depression, and somatizations scores as assessed by the Behavior Assessment System for Children (BASC-2). In addition, previous gastric and mucosal biopsies were assessed for mast cell and eosinophil densities, respectively.

Results

250 patients, ages 8 to 17 years, were assessed. Nausea was reported by 78% and was equally prevalent in those with FD alone, those with IBS alone, and those with both FD and IBS. Nausea was associated with increased mean (21.4 vs. 17.5) and peak (26.2 vs. 22.9) duodenal mast cell densities as compared those without nausea. Nausea was also associated with a wide variety of individual gastrointestinal symptoms, as well as headaches, fatigue, and dizziness. Lastly, nausea was associated with elevated self-report scores for anxiety (55.2 vs. 50.0), depression (50.2 vs. 46.1), and somatization (70.3 vs. 61.8).

Conclusions

Nausea is common in children and adolescents with pain-associated FGIDs as defined by Rome IV and is not unique to either FD or IBS. Nausea is associated with increased mucosal mast cell density, non-gastrointestinal somatic symptoms, and psychologic dysfunction.

Prevalence of Non-Celiac Gluten Sensitivity in Patients with Refractory Functional Dyspepsia: a Randomized Double-blind Placebo Controlled Trial

Refractory functional dyspepsia (RFD) is characterized by symptoms persistence in spite of medical treatment or H. pylori eradication. No study has yet investigated the presence of gluten-dependent RFD as a clinical presentation of Non-Celiac Gluten Sensitivity (NCGS). Patients with RFD, in whom celiac disease, wheat allergy and H. pylori infection had been ruled out, followed a six weeks long gluten-free diet (GFD). Symptoms were evaluated by means of visual analogue scales; patients with ≥30% improvement in at least one of the reported symptoms after GFD underwent a double-blind placebo controlled gluten challenge. Subjects were randomly divided in two groups and symptoms were evaluated after the gluten/placebo challenge. GFD responders were further followed on for 3 months to evaluate the relationship between symptoms and gluten consumption. Out of 77 patients with RFD, 50 (65%) did not respond to GFD; 27 (35%) cases showed gastrointestinal symptoms improvement while on GFD; after blind gluten ingestion, symptoms recurred in 5 cases (6.4% of patients with RFD, 18% of GFD responders) suggesting the presence of NCGS. Furthermore, such extra-intestinal symptoms as fatigue and weakness (P = 0.000), musculo-skeletal pain (P = 0.000) and headache (P = 0.002) improved in NCGS patients on GFD. Because of the high prevalence of NCGS among patients with RFD, a diagnostic/therapeutic roadmap evaluating the effect of GFD in patients with RFD seems a reasonable (and simple) approach.

Diet and functional dyspepsia: Clinical correlates and therapeutic perspectives

Hypervigilance and symptoms anticipation, visceral hypersensitivity and gastroduodenal sensorimotor abnormalities account for the varied clinical presentation of functional dyspepsia (FD) patients. Many patients recognize meals as the main triggering factor; thus, dietary manipulations often represent the first-line management strategy in this cohort of patients. Nonetheless, scarce quality evidence has been produced regarding the relationship between specific foods and/or macronutrients and the onset of FD symptoms, resulting in non-standardized nutritional approaches. Most dietary advises are indeed empirical and often lead to exclusion diets, reinforcing in patients the perception of “being intolerant” to food and self-perpetuating some of the very mechanisms underlying dyspepsia physiopathology (i.e., hypervigilance and symptom anticipation). Clinicians are often uncertain regarding the contribution of specific foods to dyspepsia physiopathology and dedicated professionals (i.e., dietitians) are only available in tertiary referral settings. This in turn, can result in nutritionally unbalanced diets and could even encourage restrictive eating behaviors in severe dyspepsia. In this review, we aim at evaluating the relationship between dietary habits, macronutrients and specific foods in determining FD symptoms. We will provide an overview of the evidence-based nutritional approach that should be pursued in these patients, providing clinicians with a valuable tool in standardizing nutritional advises and discouraging patients from engaging into indiscriminate food exclusions.

Biliary Dyskinesia in Children and Adolescents: A Mini Review

Introduction: While functional gallbladder disorder is a well-recognized and defined condition in adults, its pediatric analog, biliary dyskinesia, lacks uniformity in diagnosis. Yet, biliary dyskinesia is among the most common conditions resulting in cholecystectomy in youth and its frequency continues to rise. The primary aims of the current review were assess the efficacy of cholecystectomy in children diagnosed with biliary dyskinesia and the utility of cholescintigraphy in predicting outcomes. Results: All previous studies assessing outcomes in youth with biliary dyskinesia have been retrospective and therefore of low quality. There is a lack of uniformity in patient selection. Short term follow-up reveals partial response in 63.4-100% with complete resolution in 44.2-100%. Only 4 studies have reported long-term outcomes with complete symptom resolution in 44-60.7%. The published research generally indicates that the gallbladder ejection fraction (GBEF) as determined by cholescintigraphy lacks utility in predicting cholecystectomy outcome utilizing the commonly used cut-off values. There are data suggesting that more extreme cut-off values may improve the predictive value of GBEF. Conclusion: There is a lack of consensus on the symptom profile defining biliary dyskinesia in youth and current literature does not support the use of cholescintigraphy to select patients for cholecystectomy. There is a substantial portion of pediatric patients diagnosed with biliary dyskinesia who do not experience long-term benefit from cholecystectomy. Well-designed prospective studies of surgical outcomes are lacking. Increasing the uniformity in patient selection, including both symptom profiles and cholescintigraphy results, will be key in understanding the utility of cholecystectomy for this condition.

The role of mast cells in pediatric gastrointestinal disease

Mast cells are granulocytes derived from CD34+ pluripotent progenitor cells that demonstrate plasticity in their development, leaving the bone marrow and differentiating in the tissue where they ultimately reside. They are best known for their role in the allergic response, but also play a prominent immunoregulatory role in other processes, including immune tolerance, the innate immune response, angiogenesis, wound healing and tissue remodeling. Mast cells are found throughout the gastrointestinal tract; their metabolic products influence and regulate intestinal epithelial and endothelial function, gastrointestinal secretion, intestinal motility and absorption, and contribute to host defense. They also play an important role in the development of visceral hypersensitivity through bidirectional interaction with the enteric nervous system. Mast cells have been found to have an increasingly important role in the pathophysiology of a number of pediatric gastrointestinal diseases. This review summarizes the current understanding of the role that mast cells play in the development of pediatric gastrointestinal disorders, including eosinophilic esophagitis, functional dyspepsia, irritable bowel syndrome, celiac disease, inflammatory bowel disease, histologically negative appendicitis, Hirschsprung’s disease, intestinal neuronal dysplasia, and food protein-induced enterocolitis syndrome.

The Evolving Role of Mucosal Histology in the Evaluation of Pediatric Functional Dyspepsia: A Review

Although not required to establish the diagnosis, endoscopy with mucosal biopsy is commonly performed in the evaluation of children with dyspepsia. Traditionally, esophagogastroduodenoscopy (EGD) has been performed in children with abdominal pain to identify pathology or conversely, to “rule-out” organic disease in order to establish a diagnosis of FD. In this review, we discuss the current diagnostic yield of endoscopically-obtained biopsies in identifying disease in children and adolescents with dyspepsia including an expanded discussion of common histologic diagnoses where clinical significance has not been definitively established. In turn, we discuss the transition of endoscopy from a search for disease to a search for biologic contributors to symptom generation, while considering the growing evidence linking non-diagnostic mucosal inflammation to FD, specifically mast cells and eosinophils.

Immunopathological and molecular basis of functional dyspepsia and current therapeutic approaches

INTRODUCTION

Functional dyspepsia (FD) is widespread with 20% prevalence worldwide and a significant economic burden due to health care cost and constraints on daily activities of patients. Despite extensive investigation, the underlying causes of dyspepsia in a majority of patients remain unknown. Common complaints include abdominal discomfort, pain, burning, nausea, early satiety, and bloating. Motor dysfunction of the gut was long considered a major cause, but recent investigations suggest immune-based pathophysiological and molecular events in the duodenum are more probable contributing factors. Areas Covered: Inflammatory mediators and immune cells including duodenal eosinophils, intraepithelial lymphocytes, and T-cells have been implicated in the underlying cause of disease process, as have genetic factors. In this article, we critically reviewed findings, identified gaps in knowledge and suggested future directions for further investigation to identify targets and develop better therapeutic approaches. Expert commentary: Impaired gastric accommodation, slow gastric emptying, and increased visceral sensitivity have long been thought of as main causal factors of FD. However, more recent identification of eosinophilic degranulation and recruitment of T cells that induce mild duodenal inflammation are giving rise to new insights into immune-mediated pathophysiology. These insights offer promising avenues to explore for immune-mediated therapy in the future.

An observational study of headaches in children and adolescents with functional abdominal pain: Relationship to mucosal inflammation and gastrointestinal and somatic symptoms

Headaches and abdominal pain are among the most common pediatric pain conditions. Mast cells have been implicated in the pathophysiology of migraines, as well as functional dyspepsia (FD) and irritable bowel syndrome (IBS). The primary aims of the current study were to assess headache prevalence in patients with FD and to assess the association between headaches and mucosal mast cells and eosinophils. An additional aim was to explore associations of headache with other symptoms.We conducted a cross-sectional retrospective chart review of 235 consecutive patients with chronic abdominal pain. All patients had completed a standardized questionnaire as part of their routine clinical evaluation. Both gastrointestinal and non-gastrointestinal somatic symptoms were included in the analysis. All patients diagnosed with FD had undergone upper endoscopy with biopsies obtained from the gastric antrum and duodenum and these specimens were utilized to assess eosinophil and mast cell densities, respectively.Overall, 86% of patients fulfilled Rome IV criteria for FD. Headache was reported by 73.8% of FD patients versus 45.2% of non-FD patients (P = .001). Duodenal mast cell densities were significantly increased in those reporting headaches. Headache was not associated with any specific gastrointestinal symptoms but was associated with a wide array of non-gastrointestinal symptoms including fatigue, dizziness, muscle pain, joint pain, and chest pain.Headaches are common in children and adolescents with abdominal pain and, utilizing Rome IV criteria, are specifically associated with FD. In patients with FD, headaches are associated with increased duodenal mast cell density and a variety of somatic symptoms, all of which are possibly the result of mast cell activation.

Functional Dyspepsia: Advances in Diagnosis and Therapy

Functional dyspepsia (FD) is a common but under-recognized syndrome comprising bothersome recurrent postprandial fullness, early satiety, or epigastric pain/burning. Epidemiologically, there are two clinically distinct FD syndromes (although these often overlap clinically): postprandial distress syndrome (PDS; comprising early satiety or meal-related fullness) and epigastric pain syndrome. Symptoms of gastroesophageal reflux disease overlap with FD more than expected by chance; a subset has pathological acid reflux. The pre-test probability of FD in a patient who presents with classical FD symptoms and no alarm features is high, approximately 0.7. Coexistent heartburn should not lead to the exclusion of FD as a diagnosis. One of the most exciting observations in FD has been the consistent finding of increased duodenal eosinophilia, notably in PDS. Small bowel homing T cells, signaling intestinal inflammation, and increased cytokines have been detected in the circulation, and elevated tumor necrosis factor-α levels have been significantly correlated with increased anxiety. Postinfectious gastroenteritis is a risk factor for FD. Therapeutic options remain limited and provide only symptomatic benefit in most cases. Only one therapy is known to change the natural history of FD–Helicobacter pylori eradication. Treatment of duodenal eosinophilia is under investigation.

Up-regulation of transient receptor potential vanilloid (TRPV) and down-regulation of brain-derived neurotrophic factor (BDNF) expression in patients with functional dyspepsia (FD)

BACKGROUND

The role of immune activation in Functional Dyspepsia (FD) patients without previous infection is unclear. We compare the gastric and circulating brain-derived neurotropic factor (BDNF), receptor potential vanilloid type (TRPV) families and various cytokines in FD patients.

METHODS

Consecutive adult FD patients (Rome III) with no recent history of gastroenteritis and asymptomatic healthy controls were recruited for upper endoscopy. Subjects with GERD and IBS as predominant symptoms, diabetes mellitus, current or previous Helicobacter pylori infection, psychiatric illness and recent use of NSAID or PPI were excluded. Corpus biopsies and serum samples were collected.

KEY RESULTS

Forty three [M:F=8:35, mean age: 35.0 (9.3)] FD patients were compared with 23 healthy controls [M:F=8:15, mean age: 36.6 (10.2)]. FD patients had postprandial distress syndrome (PDS) as predominant sub-type (PDS: 36, EPS: 2). There was no significant difference in the median inflammation score (FD:0 (0-1) vs Control:0 (0-1), P=.79). However, FD patients had significantly higher mRNA expression of TRPV1 (FD:0.014±0.007, Control:0.003±0.001, 4.6 fold, P=.02) and TRPV2 (FD:0.012±0.006, Control:0.003±0.001, 4 fold, P=.02) compared to controls. The serum (FD:258.0±12.3 ng ml^-1 , Control:319.7±18.1 ng ml^-1 , P<.01) and gastric BDNF mRNA (FD:0.06±0.008, Control:0.092±0.01, 0.65 fold, P=.02)levels significantly lower in FD patients. Secretion of cytokines (IL-4, IL-5, IL-6, IL-8, IL-10, G-CSF, TGF-β2, MCP-1)was also highly correlated with dyspeptic symptoms in patients with FD.

CONCLUSIONS & INFERENCES

Despite lacking gastric mucosal inflammation, up-regulation of TRPV1 and TRPV2, down-regulation of BDNF were observed in FD patients. These suggest that immune alteration may contribute to the pathogenesis of FD without any previous infection.

Impact of gluten consumption in patients with functional dyspepsia: A case-control study

BACKGROUND AND AIM

Dietary factors and immune dysfunction may induce symptoms in patients with functional dyspepsia (FD). The aim of the study was to evaluate whether gluten consumption impacts symptom onset in patients with FD and to evaluate for possible histologic alterations in the duodenum of patients with FD.

METHODS

We prospectively enrolled 101 patients newly diagnosed with FD and 31 asymptomatic controls. Specific FD symptoms and gluten consumption patterns were evaluated by self-reported questionnaires. Tight junction protein (claudin-1) expression and presence of intraepithelial lymphocyte (IEL) infiltration in the bulb (D1) and second portion (D2) of the duodenum were assessed by immunohistochemistry.

RESULTS

Wheat bun consumption had higher frequency (P = 0.047) and increased average consumption (P = 0.01) scores in patients with FD compared with the control group. Of the 101 patients with FD, early satiety (P = 0.03) was associated with increased wheat bun consumption frequency score. On histologic evaluation, claudin-1 expression was decreased in D1 (0.003 ± 0.001 vs 0.012 ± 0.002, P = 0.003) and D2 (0.002 ± 0.0004 vs 0.012 ± 0.001, P < 0.001), while duodenal IEL counts were increased in D1 (15.5 ± 7.8 vs 3.1 ± 2.5, P < 0.001) and D2 (20.6 ± 7.7 vs 5.8 ± 3.4, P < 0.001) among patients with FD compared with the control group. Finally, Helicobacter pylori infection was associated with increased IELs in D1 (20.6 ± 7.0 vs 14.2 ± 7.4, P = 0.001) among patients with FD.

CONCLUSIONS

Among patients with FD, gluten-rich food may lead to symptom onset, specifically early satiety. Intestinal epithelial barrier dysfunction characterized by decreased claudin-1 expression and mucosal immune activation demonstrated by IEL infiltration may contribute to the pathogenesis of FD.

Biliary Dyskinesia in Children: A Systematic Review

Cholecystectomy rates for biliary dyskinesia in children are rising in the United States, but not in other countries. Biliary dyskinesia is a validated functional gallbladder disorder in adults, requiring biliary colic in the diagnosis. In contrast, most studies in children require upper abdominal pain, absent gallstones on ultrasound, and an abnormal gallbladder ejection fraction (GBEF) on cholecystokinin-stimulated cholescintigraphy for diagnosis. We aimed to systematically review existing literature in biliary dyskinesia in children, determine the validity and reliability of diagnostic criteria, GBEF, and to assess outcomes following cholecystectomy. We performed a systematic review following the PRISMA checklist and searched 7 databases including PubMed, Scopus, Embase, Ovid, MEDLINE, ProQuest, Web of Science, and the Cochrane library. Bibliographies of articles were screened for additional studies. Our search terms yielded 916 articles of which 28 were included. Three articles were manually added from searched references. We reviewed 31 peer-reviewed publications, all retrospective chart reviews. There was heterogeneity in diagnostic criteria and GBEF values. Outcomes after laparoscopic cholecystectomy varied from 34% to 100% success, and there was no consensus concerning factors influencing outcomes. The observational, retrospective study designs that comprised our review limited interpretation of safety and efficacy of the investigations and treatment in biliary dyskinesia in children. Symptoms of biliary dyskinesia overlapped with functional dyspepsia. There is a need for consensus on symptoms defining biliary dyskinesia, validation of testing required for diagnosis of biliary dyskinesia, and randomized controlled trials comparing medical versus surgical management in children with upper abdominal pain.

Increased Duodenal Eosinophil Degranulation in Patients with Functional Dyspepsia: A Prospective Study

Functional dyspepsia (FD) is a functional gastrointestinal disorder diagnosed by symptom-based criteria. It has been said that duodenal immune activation plays a role in the pathogenesis of FD. The primary aims of the study were to compare the total number of duodenal eosinophil and evaluate the eosinophil degranulation rate, number of duodenal degranulated eosinophil and mast cell between patients with FD and healthy subjects. We enrolled 96 patients with FD and 24 healthy controls at Sir Run Run Shaw Hospital. The total number of eosinophil was comparable in the second portion of duodenum (D2) and duodenal bulb (D1) between patients with FD and healthy controls (all P > 0.05). Significant higher eosinophil degranulation positive rate in D2 (P = 0.003) and a trend towards higher in D1 (P = 0.084) were observed in patients with FD compared with healthy controls. Moreover, the number of duodenal degranulated eosinophil in patients with FD were significantly increased than healthy controls in D1(9.8 ± 6.3 vs 2.9 ± 2.1 per HPF, P = 0.0002) and a trend towards increase in D2 (10.7 ± 7.7 vs 5.3 ± 0.9 per HPF, P = 0.077), respectively. However, degranulated mast cells in patients with FD were almost same with healthy controls. Increased eosinophils degranulation in duodenum play an important role in pathogenesis of FD.

Analysis of Gastric and Duodenal Eosinophils in Children with Abdominal Pain Related Functional Gastrointestinal Disorders According to Rome III Criteria

Background/Aims

Abdominal pain-related functional gastrointestinal disorder (AP-FGID) is common in children and adults. However, the mechanism of AP-FGID is not clearly known. Recently, micro-inflammation, especially eosinophilia in the gastrointestinal tract, was suggested in the pathophysiology of AP-FGID in adults. The aim of this study was to evaluate the association of gastric and duodenal eosinophilia with pediatric AP-FGID.

Methods

In total, 105 pediatric patients with AP-FGID were recruited and classified into 4 subgroups based on the Rome III criteria. Eosinophil counts in the gastric and duodenal tissues of children with AP-FGID were compared to those from normal pathology references or those of children with Helicobacter pylori infection. Tissue eosinophil counts were also compared among the 4 subtypes of AP-FGID.

Results

Eosinophil counts in the gastric antrum and body were significantly higher in children with AP-FGID than normal reference values. Duodenal eosinophil counts were higher in children with AP-FGID, but not significantly when compared with normal reference values. There were no significant differences in eosinophil counts of the stomach or duodenum among the 4 subtypes of AP-FGID. Eosinophils counts in the gastric antrum and body were significantly higher in children with H. pylori infection than in those with AP-FGID. Duodenal eosinophilia was prominent in cases of H. pylori infection, but not statistically significant when compared with AP-FGID.

Conclusions

Our study revealed that gastric eosinophilia is associated with AP-FGID in children, regardless of the subtype of functional abdominal pain. This suggests some contribution of gastrointestinal eosinophils in the development of pediatric AP-FGID.

Functional dyspepsia: new insights into pathogenesis and therapy

One in 10 people suffer from functional dyspepsia (FD), a clinical syndrome comprising chronic bothersome early satiety, or postprandial fullness, or epigastric pain or burning. Postprandial distress syndrome (PDS, comprising early satiety and/or postprandial fullness) and epigastric pain syndrome (EPS) are increasingly accepted as valid clinical entities, based on new insights into the pathophysiology and the results of clinical trials. Diagnosis is based on the clinical history, and exclusion of peptic ulcer and cancer by endoscopy. Evidence is accumulating FD and gastroesophageal ref lux disease are part of the same disease spectrum in a major subset. The causes of FD remain to be established, but accumulating data suggest infections and possibly food may play an important role in subsets. FD does not equate with no pathology; duodenal eosinophilia is now an accepted association, and Helicobacter pylori infection is considered to be causally linked to dyspepsia although only a minority will respond to eradication. In those with EPS, acid suppression therapy is a first line therapy; consider a H2 blocker even if proton pump inhibitor fails. In PDS, a prokinetic is preferred. Second line therapy includes administration of a tricyclic antidepressant in low doses, or mirtazapine, but not a selective serotonin reuptake inhibitor.

Therapeutic effect of melatonin on pediatric functional dyspepsia: A pilot study

AIM: To study the effectiveness of melatonin vs placebo in children with functional dyspepsia (FD).

METHODS: The study was conducted as a double blind, randomized, placebo controlled crossover trial. Subjects were aged 8-17 years and diagnosed with FD based on Rome III criteria. All subjects had failed to respond to 4 wk of acid suppression. Subjects receive a continuous two weeks of placebo and a continuous two weeks of melatonin in an order blinded to the participant and the study team. A Global Clinical Score was obtained to assess changes in abdominal pain. Pain was self-reported to be worse (grade 1), no change (grade 2), moderate improvement (grade 3), good (grade 4; minimal pain and not interfering with daily activities), or excellent (grade 5; no pain), respectively. A positive clinical response was defined as a grade 3 or greater response. Subjects wore an actigraph to assess sleep during a one week baseline period and during each treatment period. Subjects’ sleep latency and total sleep time were recorded throughout the duration of the study.

RESULTS: Fourteen subjects were enrolled and 12 completed the study. One withdrew prior to starting both melatonin and placebo and the other before starting melatonin. A positive clinical response (grade 3-5) was achieved in 42% of subjects on melatonin vs 50% of subjects on placebo (NS). Effect size was calculated and revealed a Cohen’s D of 0.343 which demonstrates a medium effect favoring placebo. A grade 4 or grade 5 response was seen in 4 patients on melatonin and 5 patients on placebo. Baseline sleep parameters were in the healthy range with the longest sleep latency being just over 20 min (mean 7.46 ± 8.53 min) and the shortest sleep duration just over 7 h (mean 10.09 ± 2.72 h). The mean latency did not differ between periods of treatment with melatonin as compared to placebo (4.48 ± 6.45 min vs 3.58 ± 4.24 min; NS). The mean sleep duration did not differ between periods of treatment with melatonin as compared to placebo (9.90 ± 3.53 h vs 9.41 ± 2.70 h; NS).

CONCLUSION: Melatonin does not appear to have efficacy in relieving pain in unselected pediatric FD. Future studies should consider FD subtypes, pathophysiologic mechanisms, and baseline sleep disturbances.

Present state and future challenges in pediatric abdominal pain therapeutics research: Looking beyond the forest

At the present time, it is nearly impossible to treat pediatric functional gastrointestinal disorders associated with pain in an evidence based fashion. This is due to the overall lack of controlled studies and, even more importantly, the complexity of the contributors to disease phenotype which are not controlled or accounted for in most therapeutic trials. In this manuscript, we review the challenges of defining entry criteria, controlling for the large number of biopsychosocial factors which may effect outcomes, and understanding pharmacokinetic and pharmacodynamic factors when designing therapeutic trials for abdominal pain in children. We also review the current state of pediatric abdominal pain therapeutics and discuss trial design considerations as we move forward.

Plasma ghrelin and liquid gastric emptying in children with functional dyspepsia consistent with post-prandial distress syndrome

BACKGROUND

Adult studies indicate a role for ghrelin in functional dyspepsia (FD) mediated through ghrelin's effect on gastric emptying (GE). This study examines the relationship between ghrelin, liquid GE, and pain in children with FD.

METHODS

Thirteen FD patients reporting symptoms consistent with post-prandial distress syndrome (PDS) and 17 healthy controls were enrolled. All participants received a liquid meal containing (13) C-sodium acetate. Pain severity, liquid GE utilizing exhaled (13) CO2 from the sodium acetate breath tests (ABT), plasma acyl ghrelin (AG), and des-acyl ghrelin concentrations were measured at specific intervals over 240 min following ingestion.

KEY RESULTS

FD-PDS patients demonstrated lower mean baseline AG (14.8 ± 9.7 vs 27.2 ± 14.0 fmol/mL; p = 0.013), AG Cmax (24.6 ± 8.2 vs 40.5 ± 16.8 fmol/mL; p = 0.007), and AG flux (18.2 ± 7.8 vs 32.7 ± 17.3 fmol/mL; p = 0.015) than controls. The time to reach maximum exhaled (13) CO2 concentration (T max ) was longer in FD patients than controls (47.5 ± 18.5 vs 35.8 ± 11.8 min; p = 0.046). Significant relationships between ghrelin analyte ratios and ABT parameters were largely confined to control participants.

CONCLUSIONS & INFERENCES

FD-PDS in children is associated with lower fasting and maximum AG concentrations, and dampened AG flux. These data suggest a possible role for altered ghrelin physiology in the pathogenesis of PDS.

Functional dyspepsia and the Rome criteria: a success story

The Rome III criteria for functional dyspepsia (FD), published in 2006, immediately generated controversy but have arguably helped to jump start the field in terms of mechanistic and therapeutic research. One controversy has surrounded the veracity of FD symptom subgroups and their overlap. In clinical practice the overlap of postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS) is striking. In this issue, results from Belgium suggest overlap can be reduced by reclassifying those who have postprandial pain or nausea as PDS, and meal-related symptoms predominate in FD. This is consistent with other objective experimental observations. The realization most FD occurs postmeal ingestion is driving a new conceptualization of the syndrome. For example, the observation there is an excess of duodenal eosinophils in PDS has been confirmed, with recent observations implicating increased duodenal permeability and immune activation. The link between PDS and anxiety, not identified in EPS, provides yet further evidence for distinct pathophysiological entities. While symptom-based criteria likely need refinement, the recognition of PDS and EPS has promoted exciting progress.

Anxiety Is Linked to New-Onset Dyspepsia in the Swedish Population: A 10-Year Follow-up Study

BACKGROUND & AIMS

Functional dyspepsia (FD) is associated with anxiety but it is not clear if one causes the other. We investigated whether anxiety and depression precede the onset of FD (based on the modified Rome III criteria) and gastroesophageal reflux symptoms (GERS) in a population-based follow-up study.

METHODS

Participants from the Kalixanda study (n = 3000), randomly selected from the national population register of Sweden, were given the validated Abdominal Symptom Questionnaire 1998-2001; 1000 of these participants then were selected randomly to undergo esophagogastroduodenoscopy and were given the Abdominal Symptom Questionnaire along with the Hospital Anxiety and Depression Scale questionnaire. All eligible subjects who underwent endoscopy (n = 887) were invited to participate in a follow-up study in June-August 2010 and were given the same questionnaires. Data were analyzed by logistic regression.

RESULTS

Of the 703 subjects who completed the follow-up questionnaires (79.3%); 110 were found to have FD at baseline (15.6%) and 93 at the follow-up examination (13.3%); 48 of these were new cases of FD. GERS without organic disease was reported by 273 individuals (38.8%) at baseline and by 280 at follow-up examination (39.8%); 93 cases were new. Major anxiety was associated with FD at the follow-up evaluation (odds ratio [OR], 6.30; 99% confidence interval [CI], 1.64-24.16). Anxiety was associated with postprandial distress syndrome at baseline (OR, 4.83; 99% CI, 1.24-18.76) and at the follow-up examination (OR, 8.12; 99% CI, 2.13-30.85), but not with epigastric pain syndrome. Anxiety at baseline was associated with new-onset FD at the follow-up examination (OR, 7.61; 99% CI, 1.21-47.73), but not with GERS.

CONCLUSIONS

In a study of the Swedish population, anxiety at baseline, but not depression, increased the risk for development of FD by 7.6-fold in the next 10 years. Anxiety did not affect risk for GERS.

Quantitative evaluation of duodenal eosinophils and mast cells in adult patients with functional dyspepsia

The role of duodenal eosinophils and mast cells (MCs) in the pathogenesis of functional dyspepsia (FD) remains poorly understood. This study aimed to examine the counts and degranulation of duodenal eosinophils and MCs in FD patients to explore the association between FD and both cell types. We recruited 141 FD patients and 39 healthy controls for this study. Biopsy specimens were collected from the duodenal bulb (D1) and the descending part (D2) of the duodenum of all participants. Eosinophil counts and degranulation, and MC counts and degranulation at both sites were quantitatively evaluated by hematoxylin and eosin staining, major basic protein immunostaining, and toluidine blue staining, respectively. Receiver operating characteristic analysis was applied to evaluate the diagnostic accuracy of these parameters in identifying FD cases. We found that the eosinophil counts at D2 were considerably increased in FD patients compared with healthy controls, and that the proportion of cases with eosinophil degranulation at D2 was significantly higher in the FD group. In addition, FD patients showed significantly increased MC counts and degranulation both at D1 and D2, and receiver operating characteristic analysis further demonstrated that these parameters, in particular the degranulation of MCs, appear to be highly sensitive and specific for the identification of FD patients. Our findings suggest that the increased eosinophil counts and degranulation at D2, and the increased MC counts and degranulation at D1 and D2 may be the histologic markers of FD. MC degranulation at D1 and D2 appears to be highly sensitive and specific for FD identification.

Emerging drugs for functional dyspepsia

INTRODUCTION

Functional dyspepsia (FD) is a relatively common gastrointestinal clinical condition that remains poorly understood. Controversies remain regarding the definition, pathophysiology and optimum treatment. The current treatment of FD is limited and no established regimen is available.

AREAS COVERED

Recent advances have improved our understanding of the pathophysiology of the disease and have led to the development of newer tailored therapies. Novel agents such as the motilin receptor agonist camicinal and the muscarinic M1 and M2 receptor antagonist acotiamide appear promising; however, the need for a safe and efficacious treatment remains largely unmet. This review describes the currently available management options for FD and critically evaluates emerging therapies.

EXPERT OPINION

The optimal treatment for FD is yet to be determined. A proton pump inhibitor or a prokinetic agent constitutes primary treatment. Helicobacter pylori testing and eradication is recommended. Based on currently available data, acotiamide appears promising, particularly in postprandial distress syndrome. Further large-scale multicentered trials are required to define the duration of treatment and the side-effect profile.

Visceral hypersensitivity and electromechanical dysfunction as therapeutic targets in pediatric functional dyspepsia

Functional gastrointestinal disorders (FGID) are common clinical syndromes diagnosed in the absence of biochemical, structural, or metabolic abnormalities. They account for significant morbidity and health care expenditures and are identifiable across variable age, geography, and culture. Etiology of abdominal pain associated FGIDs, including functional dyspepsia (FD), remains incompletely understood, but growing evidence implicates the importance of visceral hypersensitivity and electromechanical dysfunction. This manuscript explores data supporting the role of visceral hypersensitivity and electromechanical dysfunction in FD, with focus on pediatric data when available, and provides a summary of potential therapeutic targets.