The study on the role of inflammatory cells and mediators in post-infectious functional dyspepsia

Understanding neuroimmune interactions in disorders of gut-brain interaction: from functional to immune-mediated disorders

Functional gastrointestinal disorders-recently renamed into disorders of gut-brain interaction-such as irritable bowel syndrome and functional dyspepsia are highly prevalent conditions with bothersome abdominal symptoms in the absence of structural abnormalities. While traditionally considered as motility disorders or even psychosomatic conditions, our understanding of the pathophysiology has evolved significantly over the last two decades. Initial observations of subtle mucosal infiltration with immune cells, especially mast cells and eosinophils, are since recently being backed up by mechanistic evidence demonstrating increased release of nociceptive mediators by immune cells and the intestinal epithelium. These mediators can activate sensitised neurons leading to visceral hypersensitivity with bothersome symptoms. The interaction between immune activation and an impaired barrier function of the gut is most likely a bidirectional one with alterations in the microbiota, psychological stress and food components as upstream players in the pathophysiology. Only few immune-targeting treatments are currently available, but an improved understanding through a multidisciplinary scientific approach will hopefully identify novel, more precise treatment targets with ultimately better outcomes.

Research trends in the field of the gut-brain interaction: Functional dyspepsia in the spotlight – An integrated bibliometric and science mapping approach

Objectives

This study aims to perform a bibliometric analysis of functional dyspepsia (FD), which includes visualizing bibliographic information, in order to identify prevailing study themes, topics of interest, contributing journals, countries, institutions, and authors as well as co-citation patterns.

Methods

The Web of Science™ Core Collection Database was used to retrieve all peer-reviewed scientific publications related to FD research. The validated search terms were entered into the “title” and “author keywords” fields, and the results were sorted by publication year from 2006 to 2022. There were no restrictions on language. On 12 February 2023, a manual export of the complete metadata for each original publication and review article was performed. CiteSpace was used to reveal co-authorship, publication, and co-citation patterns to find prominent authors, organizations, countries, and journals in FD research as well as to identify author keywords with strong citation bursts, which could indicate an emerging research area. VOSviewer was used to build the co-occurrence indicator (co-word) to identify the main author keywords on which previous studies focused and to induce clustered scientific landscape for two consecutive periods to identify intriguing areas for future research.

Results

A search of the database retrieved 2,957 documents. There was a wave-like pattern in the number of publications until 2017, after which there was a spike in publication volume. The USA, China, and Japan provided the majority of contributions. In terms of institution, Mayo Clin, Univ Newcastle, and Katholieke Univ Leuven were found to be the prolific institutions. Additionally, the results indicate that eastern Asian researchers contributed significantly to the global knowledge of literature that led other countries; however, Canada, the USA, Australia, England, and Germany were found to have the highest degree of betweenness centrality. Nicholas J. Talley, Jan Tack, Gerald Holtmann, Michael Camilleri, Ken Haruma, and Paul Moayyedi occupied the top positions based on productivity and centrality indicators. Six thematic clusters emerged (Helicobacter pylori infection; pathophysiological mechanisms of FD; extraintestinal co-morbidities and overlap syndromes associated with FD; herbal medicine in FD; diabetic gastroparesis; and dietary factors in FD). “Acupuncture,” “duodenal eosinophilia,” “gut microbiota,” and others were among the author keywords with rising prevalence.

Conclusion

In FD research, eastern Asian countries have established themselves as major contributors with the highest publishing productivity; however, research has primarily been driven by North America, Europe, and Australia, where cooperation is generally more active and highly influential scientific results are produced. Our analysis suggests that increased investments, training of human resources, improved infrastructures, and expanded collaborations are essential to improving the quality of FD research in Asia. The emerging author keyword analysis suggests that eosinophil-mast cell axis, gut microbiota, mental disorders, and acupuncture are the key areas that attract researchers’ attention as future research boulevards. There is a highly skewed distribution of research output across Asia, with most focus on complementary and alternative medicine (CAM) coming from Chinese, Japanese, and South Korean centers. However, CAM remains an underexplored area of research in the context of FD, and it deserves greater research efforts in order to obtain quality scientific evidence. Furthermore, we propose that the research framework of CAM should not be limited to dysmotility; rather, it could be interpreted within a more holistic context that includes the brain-gut-microbiota axis, as well as novel concepts such as duodenitis, increased mucosal permeability, and infiltration and activation of eosinophils and mast cells, among others. Overall, we provided bibliometrics-based overviews of relevant literature to researchers from different backgrounds and healthcare professionals to provide an in-depth overview of major trends in FD research.

Role of the duodenal microbiota in functional dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a common and debilitating gastrointestinal disorder attributed to altered gut-brain interactions. While the etiology of FD remains unknown, emerging research suggests the mechanisms are likely multifactorial and heterogenous among patient subgroups. Small bowel motor disturbances, visceral hypersensitivity, chronic microinflammation, and increased intestinal tract permeability have all been linked to the pathogenesis of FD. Recently, alterations to the gut microbiome have also been implicated to play an important role in the disease. Changes to the duodenal microbiota may either trigger or be a consequence of immune and neuronal disturbances observed in the disease, but the mechanisms of influence of small intestinal flora on gastrointestinal function and symptomatology are unknown.

PURPOSE

This review summarizes and synthesizes the literature on the link between the microbiota, low-grade inflammatory changes in the duodenum and FD. This review is not intended to provide a complete overview of FD or the small intestinal microbiota, but instead outline some of the key conceptual advances in understanding the interactions between altered gastrointestinal bacterial communities; dietary factors; host immune activation; and stimulation of the gut-brain axes in patients with FD versus controls. Current and emerging treatment approaches such as dietary interventions and antibiotic or probiotic use that have demonstrated symptom benefits for patients are reviewed, and their role in modulating the host-microbiota is discussed. Finally, suggested opportunities for diagnostic and therapeutic improvements for patients with this condition are presented.

Duodenal Eosinophils and Mast Cells in Functional Dyspepsia: A Systematic Review and Meta-Analysis of Case-Control Studies

BACKGROUND & AIMS

This study explored the link between duodenal eosinophils and mast cells in patients with functional dyspepsia (FD).

METHODS

MEDLINE (PubMed) and Embase electronic databases were searched until June 2021 for case-control studies reporting duodenal eosinophils and mast cells in FD. Pooled standardized mean difference (SMD), odds ratio, and 95% CIs of duodenal eosinophils and mast cells in FD patients and controls were calculated, using a random-effects model.

RESULTS

Twenty-two case-control studies with 1108 FD patients and 893 controls were identified. Duodenal eosinophils (SMD, 1.29; 95% CI, 0.85-1.73; P = .0001) and mast cells (SMD, 2.11; 95% CI, 1.14-3.07; P = .0001) were increased in FD patients compared with controls. Substantial heterogeneity was found (I² = 93.61, P = .0001; and I² = 96.69, P = .0001, respectively) and visual inspection of funnel plots confirmed publication bias. Degranulation of duodenal eosinophils was significantly higher in FD patients compared with controls (odds ratio, 3.78; 95% CI, 6.76-4.48; P = .0001), without statistically significant heterogeneity. We conducted a sensitivity analysis for duodenal eosinophils, by including only high-quality studies, and the results remained unchanged (SMD, 1.73; 95% CI, 1.06-2.40; P = .0001), with substantial heterogeneity. Postinfectious FD patients had increased duodenal eosinophils compared with controls (SMD, 3.91; 95% CI, 1.32-6.51; P = .001) and FD patients without any history of infection (SMD, 1.42; 95% CI, 0.88-1.96; P = .001). Helicobacter pylori-negative FD patients had significantly higher duodenal eosinophils compared with controls (SMD, 3.98; 95% CI, 2.13-5.84; P = .0001), with substantial heterogeneity. No significant difference in duodenal eosinophils was seen according to FD subtypes.

CONCLUSIONS

This meta-analysis suggests a link between duodenal microinflammation and FD. However, the quality of evidence is very low, largely owing to the unexplained heterogeneity and serious risk of publication bias in all comparative analyses. Thus, causality remains uncertain and further studies are required.

Immune Activation in Functional Dyspepsia: Bystander Becoming the Suspect

Disorders of gut-brain interaction (DGBI), formerly termed functional gastrointestinal disorders (FGID), are highly prevalent although exact pathophysiological mechanisms remain unclear. Intestinal immune activation has been recognized, but increasing evidence supports a pivotal role for an active inflammatory state in these disorders. In functional dyspepsia (FD), marked eosinophil and mast cell infiltration has been repeatedly demonstrated and associations with symptoms emphasize the relevance of an eosinophil-mast cell axis in FD pathophysiology. In this Review, we highlight the importance of immune activation in DGBI with a focus on FD. We summarize eosinophil biology in both homeostasis and inflammatory processes. The evidence for immune activation in FD is outlined with attention to alterations on both cellular and molecular level, and how these may contribute to FD symptomatology. As DGBI are complex and multifactorial conditions, we shed light on factors associated to, and potentially influencing immune activation, including bidirectional gut-brain interaction, allergy and the microbiota. Crucial studies reveal a therapeutic benefit of treatments targeting immune activation, suggesting that specific anti-inflammatory therapies could offer renewed hope for at least a subset of DGBI patients. Lastly, we explore the future directions for DGBI research that could advance the field. Taken together, emerging evidence supports the recognition of FD as an immune-mediated organic-based disorder, challenging the paradigm of a strictly functional nature.

A Survey of Methodologies for Assessing Mast Cell Density and Activation in Patients with Functional Abdominal Pain Disorders

The aim was to assess methods utilized in assessing mast cell involvement in functional abdominal pain disorders (FAPDs), specifically to describe variability in methods utilized to assess both mast cell density and activation and determine if a consensus exists. After a literature search identified 70 manuscripts assessing mast cell density, data were extracted including FAPD diagnosis, site of biopsy, selection of microscopic fields analyzed, selection of mucosal region analyzed, method of mast cell identification, method to assess mast cell density, and if performed, method to assess mast cell activation. There appears to be some consensus favoring inmmunohistochemical stains over histochemical stains for identifying mast cells. Otherwise, considerable variability exists in methodology for assessing mast cell density and activation. Regardless of method, approximately 80% of studies found increased mast cell density and/or activation in comparison to controls with no method being superior. A wide variety of methods have been employed to assess mast cell density and activation with no well-established consensus and inadequate data to recommend specific approaches. The current methodology providing physiologic information needs to be translated to a standard methodology providing clinical information with the development of criteria establishing abnormal density and/or activation, and more importantly, predicting treatment response.

Inflammation and Overlap of Irritable Bowel Syndrome and Functional Dyspepsia

Irritable bowel syndrome (IBS) and functional dyspepsia (FD) are common functional gastrointestinal disorders (FGIDs) and account for a large proportion of consulting patients. These 2 disorders overlap with each other frequently. The pathogenesis of IBS or FD is complicated and multi-factors related, in which infectious or non-infectious inflammation and local or systemic immune response play significant roles. There are few studies focusing on the mechanism of inflammation in patients with overlap syndrome of irritable bowel syndrome and functional dyspepsia (IBS-FD). This review focuses on current advances about the role of inflammation in the pathogenesis of IBS and FD and the possible mechanism of inflammation in IBS-FD.

Vagal gut-brain signaling mediates amygdaloid plasticity, affect, and pain in a functional dyspepsia model

Functional dyspepsia (FD) is associated with chronic gastrointestinal distress and with anxiety and depression. Here, we hypothesized that aberrant gastric signals, transmitted by the vagus nerve, may alter key brain regions modulating affective and pain behavior. Using a previously validated rat model of FD characterized by gastric hypersensitivity, depression-like behavior, and anxiety-like behavior, we found that vagal activity - in response to gastric distention - was increased in FD rats. The FD phenotype was associated with gastric mast cell hyperplasia and increased expression of corticotrophin-releasing factor (Crh) and decreased brain-derived neurotrophic factor genes in the central amygdala. Subdiaphragmatic vagotomy reversed these changes and restored affective behavior to that of controls. Vagotomy partially attenuated pain responses to gastric distention, which may be mediated by central reflexes in the periaqueductal gray, as determined by local injection of lidocaine. Ketotifen, a mast cell stabilizer, reduced vagal hypersensitivity, normalized affective behavior, and attenuated gastric hyperalgesia. In conclusion, vagal activity, partially driven by gastric mast cells, induces long-lasting changes in Crh signaling in the amygdala that may be responsible for enhanced pain and enhanced anxiety- and depression-like behaviors. Together, these results support a "bottom-up" pathway involving the gut-brain axis in the pathogenesis of both gastric pain and psychiatric comorbidity in FD.

Mucosal Th17 Cells Are Increased in Pediatric Functional Dyspepsia Associated with Chronic Gastritis

BACKGROUND

Chronic gastritis is a common histologic finding in children with functional dyspepsia (FD). While Th17 cells have been implicated in other forms of gastritis, they have not been evaluated in chronic gastritis.

AIMS

The aim of the current study was to assess Th17 cells in children with FD with and without chronic gastritis.

METHODS

Densities were determined for Th17 cells, eosinophils, and mast cells, respectively, in both the gastric antrum and the duodenum. Densities were compared between five groups: FD with chronic gastritis (N = 20), FD without chronic gastritis (N = 20), Helicobacter pylori-associated gastritis (N = 10), Crohn's gastritis (N = 10), and normal controls (N = 10). Th17 densities were also compared between patients with and without early satiety.

RESULTS

FD with chronic gastritis was associated with higher Th17 cell density as compared to normal controls and comparable to both H. pylori-associated gastritis and Crohn's gastritis. Eosinophil and mast cell densities were higher in FD patients with chronic gastritis as compared to either FD without gastritis or normal controls. Th17 density was higher in patients reporting early satiety but not in those with epigastric pain.

CONCLUSIONS

FD with chronic gastritis is associated with higher Th17 cell, eosinophil, and mast cell density as compared to FD without chronic gastritis or normal controls. Chronic gastritis demonstrated Th17 cell density similar to that seen in other conditions where Th17 cells are believed to play a pathogenic role. Th17 cells may represent another therapeutic target in these patients.

The Altered Mucosal Barrier Function in the Duodenum Plays a Role in the Pathogenesis of Functional Dyspepsia

BACKGROUND

An altered gastrointestinal barrier function is reportedly associated with the pathogenesis of functional dyspepsia (FD); however, the pathogenesis of FD has not yet been fully elucidated.

AIMS

The objective of the present study was to determine whether the mucosal barrier function is impaired in patients with FD and to investigate the mechanisms underlying FD.

METHODS

The present study included patients with FD (FD group, n = 24), non-FD patients with abdominal symptoms (symptomatic control group, n = 14), and patients with no abdominal symptoms (asymptomatic control group, n = 20). The groups were compared regarding the mucosal electrical impedance (MI) values of the stomach and duodenum, which were measured using a tissue conductance meter during esophagogastroduodenoscopy.

RESULTS

There were no significant differences between the three groups in the MI of the stomach. In contrast, the duodenal MI of the FD group (17.8 ± 4.3 Ω) was significantly lower than those of the symptomatic control group (27.2 ± 6.4 Ω, p < 0.0001) and asymptomatic control group (23.0 ± 7.4 Ω, p = 0.016). The expression of zonula occludens-1 (ZO-1) was significantly lower in the FD group than in the symptomatic control group (p = 0.011), where ZO-1 was positively correlated with the duodenal MI (β = 0.513, p = 0.017). The interleukin (IL)-1β expression was significantly higher in the FD group than in the symptomatic control group (p = 0.041), where IL-1β was inversely correlated with the duodenal MI (β = - 0.600, p = 0.004).

CONCLUSIONS

The mucosal barrier function of the duodenum was altered in patients with FD. Both a decreased ZO-1 and increased IL-1β may play a role in the pathogenesis of FD.

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.

Pharmacological treatments for functional nausea and functional dyspepsia in children: a systematic review

INTRODUCTION

Chronic idiopathic nausea (CIN) and functional dyspepsia (FD) cause considerable strain on many children's lives and their families. Areas covered: This study aims to systematically assess the evidence on efficacy and safety of pharmacological treatments for CIN or FD in children. CENTRAL, EMBASE, and Medline were searched for Randomized Controlled Trials (RCTs) investigating pharmacological treatments of CIN and FD in children (4-18 years). Cochrane risk of bias tool was used to assess methodological quality of the included articles. Expert commentary: Three RCTs (256 children with FD, 2-16 years) were included. No studies were found for CIN. All studies showed considerable risk of bias, therefore results should be interpreted with caution. Compared with baseline, successful relief of dyspeptic symptoms was found for omeprazole (53.8%), famotidine (44.4%), ranitidine (43.2%) and cimetidine (21.6%) (p = 0.024). Compared with placebo, famotidine showed benefit in global symptom improvement (OR 11.0; 95% CI 1.6-75.5; p = 0.02). Compared with baseline, mosapride versus pantoprazole reduced global symptoms (p = 0.011; p = 0.009). One study reported no occurrence of adverse events. This systematic review found no evidence to support the use of pharmacological drugs to treat CIN or FD in children. More high-quality clinical trials are needed.

ABBREVIATIONS

AP-FGID: Abdominal Pain Related Functional Gastrointestinal Disorders; BART: Biofeedback-Assisted Relaxation Training; CIN: Chronic Idiopathic Nausea; COS: Core Outcomes Sets; EPS: Epigastric Pain Syndrome; ESPGHAN: European Society for Pediatric Gastroenterology Hepatology and Nutrition; FAP: Functional Abdominal Pain; FD: Functional Dyspepsia; GERD: Gastroesophageal Reflux Disease; GES: Gastric Electrical Stimulation; H2RAs: H2 Receptor Antagonists; IBS: irritable bowel syndrome; NASPGHAN: North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition; PDS: Postprandial Distress Syndrome; PPIs: Proton Pump Inhibitor; PROMs: Patient Reported Outcome Measures; RCTs: Randomized Controlled Trials; SSRIs: selective serotonin reuptake inhibitors; TCAs: tricyclic antidepressants.

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.

Role of the Duodenum in the Pathogenesis of Functional Dyspepsia: A Paradigm Shift

Functional dyspepsia (FD) is a common disorder characterized by chronic epigastric pain or burning, or bothersome postprandial fullness or early satiation, without a definitive organic cause. The pathogenesis of FD is likely heterogeneous. Classically, motor disorders, visceral hypersensitivity, and brain-gut interactions have been implicated in the pathophysiology of FD, but recently an important role for chronic low-grade inflammation and infection in FD has been reported and confirmed. Duodenal low-grade inflammation is frequently observed in FD in those with and without documented previous gastroenteritis. Duodenal eosinophils and in some cases mast cells may together or separately play a key role, and immune activation (eg, circulating homing small intestinal T cells) has been observed in FD. Low-grade intestinal inflammation in patients with FD may provoke impairment in motor-sensory abnormalities along the gastrointestinal neural axis. Among FD patients, the risk of developing dyspeptic symptoms after a bout of gastroenteritis is 2.54 (95% CI, 1.76–3.65) at more than 6 months after acute gastroenteritis. Gut host and microbial interactions are likely important, and emerging data demonstrate both quantitative and qualitative changes of duodenal mucosal and fecal microbiota in FD. Food antigens (eg, wheat proteins) may also play a role in inducing duodenal inflammation and dyspepsia. While causation is not established, the hypothesis that FD is a disorder of microscopic small intestinal inflammation in a major subset is gaining acceptance, opening the possibility of novel treatment approaches that may be able to alter the natural history of the disorder.

Micro-inflammation in functional dyspepsia: A systematic review and meta-analysis

Functional dyspepsia (FD) is a gastrointestinal disorder of unknown etiology. Although micro-inflammation appears to be important in the pathogenesis, studies evaluating immune activation in FD have been inconsistent. A systematic review of literature and meta-analysis was performed to compare immunologic cell counts and cytokine levels in the mucosa and peripheral blood of individuals with FD and healthy controls. PubMed, Embase, and the Cochrane library were searched. Data on immunologic cell counts and cytokines levels among individuals with FD and control groups were extracted and compared by calculating standard mean differences (SMD). Thirty-seven studies met the inclusion criteria. Mast cell (SMD = 0.94, 95%CI 0.26-1.62, P = .007) and eosinophil counts (SMD = 0.36, 95%CI 0.06-0.68, P = .03) in the stomach were increased, among individuals with FD compared to controls. Similarly, mast cell (SMD = 0.66, 95%CI 0.20-1.13, P = 0.005) and eosinophil (SMD = 0.95, 95%CI 0.66-1.24; P < .001) counts in the duodenum were also increased in those with FD compared to controls. In a subgroup analysis, elevated eosinophil counts in the duodenum were observed in both post-prandial distress syndrome (SMD = 0.97, 95%CI 0.46-1.47, P = .0002) and epigastric pain syndrome subtypes (SMD = 1.16, 95%CI 0.48-1.83, P = .0008). No differences in mucosal intraepithelial lymphocyte, enterochromaffin cell, and neutrophil counts, as well as, peripheral interlukin-6 (IL-6) and IL-10 levels were observed among individuals with FD and controls. Micro-inflammation in the form of local immune cell infiltration, particularly eosinophils and mast cells, characterizes the pathogenesis of FD.

Definition, Pathogenesis, and Management of That Cursed Dyspepsia

Dyspepsia is an umbrella term used to encompass a number of symptoms thought to originate from the upper gastrointestinal tract. These symptoms are relatively nonspecific; not surprisingly, therefore, a myriad of conditions may present with any one or a combination of these symptoms. Therein lays the clinician's first challenge: detecting the minority who may have a potentially life-threatening disorder, such as gastric cancer, from a population whose symptoms are, for the most part, considered functional in origin. The second challenge lies in the definition and management of those individuals with functional dyspepsia (FD); the major focus of this review. The Rome process has addressed the issue of FD definition and a look back at the evolution of Rome criteria for this disorder illustrates the complexities that have so frustrated us. There has been no shortage of hypotheses to explain symptom pathogenesis in FD; initially focused on gastric sensorimotor dysfunction, these have now strayed well into the duodenum and have come to entertain such factors as immune responses and the microbiome. FD has proven to be an equally challenging area for therapeutics; while the staple approaches of acid suppression and eradication of Helicobacter pylori have some limited efficacy in select populations, strategies to ameliorate symptoms in the majority of sufferers based on presumed pathophysiology have largely foundered. Lacking a validated biomarker(s) FD continues to be an elusive target and is likely to remain so until we can better define the various phenotypes that it must surely contain.

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.

Functional dyspepsia

Functional dyspepsia is one of the most prevalent functional gastrointestinal disorders. Functional dyspepsia comprises three subtypes with presumed different pathophysiology and aetiology: postprandial distress syndrome (PDS), epigastric pain syndrome (EPS) and a subtype with overlapping PDS and EPS features. Functional dyspepsia symptoms can be caused by disturbed gastric motility (for example, inadequate fundic accommodation or delayed gastric emptying), gastric sensation (for example, sensations associated with hypersensitivity to gas and bloating) or gastric and duodenal inflammation. A genetic predisposition is probable but less evident than in other functional gastrointestinal disorders, such as irritable bowel syndrome (IBS). Psychiatric comorbidity and psychopathological state and trait characteristics could also play a part, although they are not specific to functional dyspepsia and are less pronounced than in IBS. Possible differential diagnoses include Helicobacter pylori infection and peptic ulceration. Pharmacological therapy is mostly based on the subtype of functional dyspepsia, such as prokinetic and fundus-relaxing drugs for PDS and acid-suppressive drugs for EPS, whereas centrally active neuromodulators and herbal drugs play a minor part. Psychotherapy is effective only in a small subset of patients, whereas quality of life can be severely affected in nearly all patients. Future therapies might include novel compounds that attempt to treat the underlying gastric and duodenal inflammation.

Histomorphological Spectrum of Duodenal Pathology in Functional Dyspepsia Patients

INTRODUCTION

Functional Dyspepsia (FD) is one of the most common causes of gastrointestinal symptoms aetiology of which is poorly understood.

AIM

To study duodenal histomorphological features and their relationship with Helicobacter pylori (H Pylori) infection in patients of FD.

MATERIALS AND METHODS

This case control study included 50 cases of FD patients selected according to Rome III criteria and 30 age and sex matched controls. These were subjected to oesophago-gastro-duodenoscopy, rapid urease test for detection of H. pylori on gastric antral biopsy and duodenal biopsy from second part of duodenum for histopathological evaluation by light microscopy. Ten antral urease positive cases of FD with highest Intraepithelial Lymphocyte Count (IEL) were subjected to Immunohistochemistry (IHC).

RESULTS

Duodenal inflammation was an invariable feature noted in FD. Morphological spectrum consisted of increased IEL in 72%, increased duodenal eosinophils in 92%, presence of focal villous atrophy in 16%, lymphoid aggregates, colonic metaplasia, and duodenal H. pylori infection in 4% each. Gastric H. pylori positivity was noted in 48% cases of FD. Increased duodenal IEL count and duodenal eosinophilia was noted in 75%, 87.5% such cases. Same was noted respectively, with 61.5% and 95.15% cases with gastric H. pylori negativity. In cases of FD, duodenal IEL and eosinophil count in lamina propria showed statistically significant rise when compared with control and had positive correlation with gastric H pylori infection. On IHC, increased expression of CD 8 was noted in duodenal IEL and lymphocytes in lamina propria as compared to CD4.

CONCLUSION

Our study provided some insight in pathogenesis of FD and role of H. pylori in its aetiology.

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.

The normoglycaemic biobreeding rat: a spontaneous model for impaired gastric accommodation

OBJECTIVE

Impaired gastric accommodation is reported in patients with functional dyspepsia (FD). Previous findings in postinfectious patients with FD suggest that low-grade inflammation and dysfunction of nitrergic nerves play a role in impaired accommodation. To date, spontaneous animal models to study the relationship between these changes are lacking. We hypothesise that the normoglycaemic BioBreeding diabetes-prone (BB-DP) rat provides an animal model of inflammation-induced impaired gastric motor function.

DESIGN

Control diabetes-resistant biobreeding, normoglycaemic and hyperglycaemic BB-DP rats were sacrificed at the age of 30, 70 and 220 days and gastric fundus tissue was harvested to study nitrergic motor control, inflammation and expression of neuronal isoform of nitric oxide synthase (nNOS) and inducible isoform of nitric oxide synthase (iNOS). Nutrient-induced changes in intragastric pressure (IGP) were measured in normoglycaemic BB-DP rats to study accommodation.

RESULTS

No differences in nitrergic function and inflammation were observed between BB-DP and control rats at 30 days. The nitrergic component of the fundic muscle relaxation was reduced in BB-DP rats of 70 and 220 days. This was accompanied by a significant loss of nNOS proteins. IGP significantly increased during nutrient infusion in BB-DP rats of 220 days, indicating impaired accommodation. Infiltration of polymorphonuclear cells, increased myeloperoxidase activity and increased expression of iNOS was observed in the fundic mucosa and muscularis propria of 70-day-old and 220-day-old BB-DP rats.

CONCLUSIONS

BB-DP rats of 220 days display altered fundic motor control and impaired accommodation, which is least partially explained by loss of nitrergic function. This may be related to inflammatory changes in the neuromuscular layer, suggesting that normoglycaemic BB-DP rats provide a spontaneous model for inflammation-induced impaired gastric accommodation.

The role of mast cells in functional GI disorders

Functional gastrointestinal disorders (FGIDs) are characterized by chronic complaints arising from disorganized brain-gut interactions leading to dysmotility and hypersensitivity. The two most prevalent FGIDs, affecting up to 16-26% of worldwide population, are functional dyspepsia and irritable bowel syndrome. Their etiopathogenic mechanisms remain unclear, however, recent observations reveal low-grade mucosal inflammation and immune activation, in association with impaired epithelial barrier function and aberrant neuronal sensitivity. These findings come to challenge the traditional view of FGIDs as pure functional disorders, and relate the origin to a tangible organic substrate. The mucosal inflammatory infiltrate is dominated by mast cells, eosinophils and intraepithelial lymphocytes in the intestine of FGIDs. It is well established that mast cell activation can generate epithelial and neuro-muscular dysfunction and promote visceral hypersensitivity and altered motility patterns in FGIDs, postoperative ileus, food allergy and inflammatory bowel disease. This review will discuss the role of mucosal mast cells in the gastrointestinal tract with a specific focus on recent advances in disease mechanisms and clinical management in irritable bowel syndrome and functional dyspepsia.

Efficacy and safety of honey based formulation of Nigella sativa seed oil in functional dyspepsia: A double blind randomized controlled clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

A honey based formulation from Nigella sativa L. (N. sativa) has been used in Traditional Persian Medicine for upper gastrointestinal symptoms. Considering the traditional use of this formulation and its ingredients known pharmacologic effects, this study aimed to evaluate the efficacy and safety of N. sativa seed oil mixed with honey in treatment of patients with functional dyspepsia.

METHODS AND MATERIALS

Seventy patients diagnosed with functional dyspepsia according to ROME III criteria and confirmed by upper gastrointestinal endoscopy were selected to receive a traditional honey based formulation of N. sativa (5 ml N. sativa oil orally daily) or placebo for 8 weeks in a double-blind randomized placebo-controlled clinical trial using a parallel design with a 1:1 allocation ratio. Patients were evaluated prior to and following 8 weeks of the intervention in terms of the Hong Kong index of dyspepsia severity, presence of Helicobacter pylori infection based on urease test, scores in different domains of short form (SF-36) health survey, and any observed adverse events.

RESULTS

The mean scores of Hong Kong index of dyspepsia severity sores and the rate of H. pylori infection were significantly lower in the N. sativa group comparing the placebo group after the intervention (P<0.001). No serious adverse event was reported.

CONCLUSION

This study showed that adjuvant supplementation of honey based formulation of N. sativa can cause significant symptomatic improvement of patients with functional dyspepsia whom received the standard anti-secretory therapy. The results should be investigated further in studies with longer duration and larger sample size.

Dysbiotic infection in the stomach

Microbiota in human alimentary tract plays important roles for homeostatic maintenance of the body. Compositional difference of gut microbiota is tightly associated with susceptibility of many diseases, including inflammatory diseases, obesity, diabetes mellitus, cancer, and atherosclerosis. “Dysbiosis” refers to a state of imbalance among the colonies of microorganisms within the body, which brings abnormal increase of specific minor components and decrease in the normally dominant species. Since stomach secrets strong acid for its digestive role, this organ has long been thought a sterile organ. However, the discovery of Helicobacter pylori (H. pylori) has changed the concept. This bacterium has proven to cause gastritis, peptic ulcer, and gastric cancer. However, recent cross-sectional studies revealed that H. pylori carriers had a decreased risk of developing immunological diseases, such as asthma. H. pylori coinfection also suppresses inflammatory bowel diseases. This review describes human gastric microbiota by discussing its mutual interaction and pathogenic enrollment. Gastric “dysbiosis” may affect host inflammatory response and play important role for gastric pathogenesis. We will topically discuss enrollment of dysbiosis for genesis of gastric cancer as well as for disruption of immunological homeostasis affecting oncogenic resistance.

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.

Systematic review with meta-analysis: post-infectious functional dyspepsia

BACKGROUND

The prevalence of functional dyspepsia (FD) following infectious gastroenteritis has not been systematically reviewed.

AIM

To conduct a systematic review and calculate the summary odds ratio (OR) for the development of FD following infectious gastroenteritis, as compared to a control population.

METHODS

Published studies in PubMed, EmBASE, and Cochrane Database and abstracts from standard sources were screened for eligible studies. Data from studies meeting inclusion criteria were pooled for meta-analysis.

RESULTS

Nineteen studies were eligible for inclusion. The mean prevalence of FD following acute gastroenteritis (AGE) was 9.55% (FD, n = 909; AGE, n = 9517) in adult populations. The summary OR for the development of post-infectious FD was 2.54 (95% CI = 1.76-3.65) at more than 6 months after AGE, as compared to the prevalence in controls within the same population. This is compared with the summary OR (3.51; 95% CI = 2.05-6.00) for the development of post-infectious irritable bowel syndrome (IBS) in the same population at more than 6 months after AGE. There was significant statistical heterogeneity with an I(2) of 72.8% for the summary OR of post-infectious FD. Several pathogens, including Salmonella spp., Escherichia coli O157, Campylobacter jejuni, Giardia lamblia and Norovirus have been shown to be associated with post-infectious FD symptoms.

CONCLUSIONS

Infectious gastroenteritis is associated with an increased risk for subsequent dyspepsia as well as for irritable bowel syndrome. Post-infectious FD and post-infectious irritable bowel syndrome may represent different aspects of the same pathophysiology. Further studies will be needed to determine this.

Helicobacter pylori and functional dyspepsia: An unsolved issue?

Patients with Helicobacter pylori (H. pylori) infection may complain of dyspeptic symptoms without presence of macroscopic lesions on gastroduodenal mucosa. Such a condition is usually recognized as functional dyspepsia, and different pathogenetic mechanisms are involved. The role of H. pylori in these patients is controversial. Several trials assessed the potential role of H. pylori eradication in improving dyspeptic symptoms, and data of some meta-analyses demonstrated that cure of infection is associated with a small (10%), but significant therapeutic gain as compared to placebo. The reason for which dyspeptic symptoms regress in some patients following bacterial eradication, but persist in others remains unclear. Regrettably, trials included in the meta-analyses are somewhat different for study design, definition of symptoms, assessment of symptoms changes, and some may be flawed by potential pitfalls. Consequently, the information could be not consistent. We critically reviewed the main available trials, attempting to address future research in this field

Gastroduodenal mechanisms underlying functional gastric disorders

Functional dyspepsia (FD), a disorder thought to originate from the gastroduodenum, is one of the most prevalent functional gastrointestinal disorders. In this review, we focused on gastroduodenal mechanisms involved in the pathophysiology of FD. The roles of impaired gastric accommodation, delayed gastric emptying, hypersensitivity to gastric distention and to luminal agents, altered mucosal integrity, low-grade inflammation and psychological stress are reviewed. The underlying pathophysiology in FD is probably multifactorial, involving a combination of several of these factors, ultimately leading to symptom pattern and severity.

Duodenal eosinophilia and early satiety in functional dyspepsia: confirmation of a positive association in an Australian cohort

BACKGROUND AND AIM

Functional dyspepsia (FD), defined by unexplained pain or discomfort centered in the upper abdomen, is common. Diagnosis and treatment of FD based on the symptom-based Rome criteria remains challenging. Recently, eosinophilia in the duodenum has been implicated in the pathophysiology of FD in adults, specifically increased eosinophils in early satiety and postprandial distress, but the association remains controversial. The aim of this study was to characterize upper gastrointestinal (GI) tract pathology, specifically duodenal eosinophilia, in an Australian cohort of patients with FD.

METHODS

Patients prospectively referred for an upper GI endoscopy (n = 55; mean age, 49.6 years; 61.8% female) were stratified to FD cases (n = 33) and controls (n = 22) using Rome II criteria. All subjects completed a validated bowel symptom questionnaire. The eosinophil count per square millimeter in the duodenal bulb (D1) and second part (D2) was assessed and Helicobacter pylori status determined by gastric histology. Associations with clinical symptoms were assessed.

RESULTS

Cases and controls were demographically similar. Duodenal eosinophilia was significantly increased in subjects experiencing early satiety (P = 0.01) and postprandial fullness (P = 0.001). This association was seen in D2 but not D1. Abdominal pain was associated with eosinophilia in both D1 (P = 0.02) and D2 (P = 0.005). Smoking was also associated with higher eosinophil counts in D2 (P = 0.007) and symptoms of early satiety (P = 0.02).

CONCLUSIONS

Duodenal eosinophilia occurs in a subset of FD. The potential role of duodenal eosinophils in FD has implications for diagnosis and therapeutic trials.

Functional dyspepsia patients have lower mucosal cholecystokinin concentrations in response to duodenal lipid

BACKGROUND

Dyspeptic symptoms are frequently induced, or exacerbated, by fatty food ingestion. Excessive release of, and/or hypersensitivity to, cholecystokinin (CCK) may explain the exaggerated response to lipid in patients with functional dyspepsia (FD). Thus far, plasma CCK response has been evaluated. However, stimulation of CCK1 receptors on duodenal vagal afferents occurs in a paracrine manner, suggesting that mucosal CCK concentrations are relevant to quantify. Apolipoprotein A-IV stimulates mucosal CCK release.

AIM

To investigate the hypothesis that fat-induced release of CCK and apolipoprotein A-IV (apoA-IV) is enhanced in the duodenum of FD patients.

PATIENTS AND METHODS

Sixteen symptomatic FD patients and 10 healthy volunteers (HV) underwent duodenal perfusion with intralipid 20%, 2 kcal/min, for 60 min. Symptoms were scored and blood samples were collected every 15 min during lipid perfusion and 15 min after discontinuation when duodenal biopsies were taken. Plasma and mucosal concentrations of CCK and apoA-IV were quantified.

RESULTS

Abdominal discomfort (P=0.001), nausea (P=0.05), and fullness (P=0.005) in response to duodenal lipid increased significantly only in FD patients. Following lipid infusion, the mean mucosal CCK concentration was lower in FD patients compared with HV (P<0.0001). Fasting concentrations and plasma response of CCK were comparable in FD patients and HV. Plasma apoA-IV response appeared to differ between patients and HV, whereas mucosal apoA-IV concentrations were similar.

CONCLUSION

Our results suggest excessive local release of CCK in response to duodenal lipid in FD. This likely causes exaggerated stimulation of duodenal vagal afferents, explaining dyspeptic symptom generation. The mechanisms underlying elevated mucosal CCK release warrant further investigation.

Eosinophils and mast cells as therapeutic targets in pediatric functional dyspepsia

There is an increasing appreciation for the importance of inflammation as a pathophysiologic entity that contributes to functional gastrointestinal disorders including functional dyspepsia (FD). Importantly, inflammation may serve as a mediator between psychologic and physiologic functions. This manuscript reviews the literature implicating two inflammatory cell types, mast cells and eosinophils, in the generation of dyspeptic symptoms and explores their potential as targets for the treatment of FD. There are a number of inciting events which may initiate an inflammatory response, and the subsequent recruitment and activation of mast cells and eosinophils. These include internal triggers such as stress and anxiety, as well as external triggers such as microbes and allergens. Previous studies suggest that there may be efficacy in utilizing medications directed at mast cells and eosinophils. Evidence exists to suggest that combining “anti-inflammatory” medications with other treatments targeting stress can improve the rate of symptom resolution in pediatric FD.

Changes in gastrointestinal tract function and structure in functional dyspepsia

Functional dyspepsia is an extremely common disorder of gastrointestinal function. The disorder is thought to be heterogeneous, with different pathophysiological mechanisms underlying varied symptom patterns. A diversity of changes in gastrointestinal tract function and structure has been described in functional dyspepsia. These involve alterations in the stomach, such as impaired accommodation, delayed gastric emptying and hypersensitivity, and alterations in the duodenum, such as increased sensitivity to duodenal acid and/or lipids and low-grade inflammation. In this Review, we summarize all these abnormalities in an attempt to provide an integrated overview of the pathophysiological mechanisms in functional dyspepsia.

Tibetan herbal formula Padma Digestin modulates gastrointestinal motility in vitro

AIM: To examine the effects of Padma Digestin on the smooth muscle motility of different gastrointestinal segments in vitro.

METHODS: The effects of the ethanolic extract of Padma Digestin (at 8.16 mg/mL or 81.6 mg/mL) on the contractility and susceptibility to acetylcholine (ACh) of muscle strips from the cardia, antrum, pylorus, duodenum, jejunum, ileum and colon of male Wistar rats were analyzed.

RESULTS: Compared with the control treatment, the Padma Digestin extract had a procontractile effect on the antral smooth muscle strips. Padma Digestin decreased ACh sensitivity in cardia muscle strips and increased it in those from the antrum and pylorus. In the intestinal segments, spontaneous contractility was inhibited in both the duodenal and jejunal strips, whereas reactivity to ACh was inhibited in the jejunal strips only. In the colonic samples, Padma Digestin inhibited spontaneous and ACh-stimulated contractility at a low dose but seems to have increasing effects at a high dose.

CONCLUSION: Padma Digestin extract has region-specific effects on the contractility and excitability of gastrointestinal smooth muscle. Our results support the traditional use of Padma Digestin for maldigestion and functional gastrointestinal disorders.

Investigating functional dyspepsia in Asia

The diagnosis of functional dyspepsia (FD) is challenging since it depends largely on symptoms which are often heterogeneous and overlapping. This is particularly so in Asia with many different cultures and languages. Symptom-based diagnosis of FD based on Rome III criteria has not been fully validated and it may not be suitable in some Asian populations. Clinicians often assume that investigations in FD are not rewarding and physiological tests are often not available unless in the research setting. Investigation of alarm features and role of Helicobacter pylori in FD remain controversial but experts agreed that both should be tested. Physiological tests including gastric accommodation and chemical hypersensitivity tests are underutilized in Asia and available studies were few. While experts do not recommend routine clinical use of gastric accommodation tests but they agree that these tests can be advocated if clinically indicated. Empiric therapeutic trial is not currently a diagnostic option. The pathogenesis of FD is still poorly understood and there is a substantial placebo response. As a conclusion, a diagnosis of FD is challenging especially so in the context of Asia and despite the limitations of available physiological tests experts agreed that these tests can be advocated if and when clinically indicated.

Asian consensus report on functional dyspepsia

BACKGROUND AND AIM

Environmental factors such as food, lifestyle and prevalence of Helicobacter pylori infection are widely different in Asian countries compared with the West, and physiological functions and genetic factors of Asians may also be different from those of Westerners. Establishing an Asian consensus for functional dyspepsia is crucial in order to attract attention to such data from Asian countries, to articulate the experience and views of Asian experts, and to provide a relevant guide on management of functional dyspepsia for primary care physicians working in Asia.

METHODS

Consensus team members were selected from Asian experts and consensus development was carried out by using a modified Delphi method. Consensus teams collected published papers on functional dyspepsia especially from Asia and developed candidate consensus statements based on the generated clinical questions. At the first face-to-face meeting, each statement was reviewed and e-mail voting was done twice. At the second face-to-face meeting, final voting on each statement was done using a keypad voting system. A grade of evidence and strength of recommendation were applied to each statement according to the method of the GRADE Working Group.

RESULTS

Twenty-nine consensus statements were finalized, including seven for definition and diagnosis, five for epidemiology, nine for pathophysiology, and eight for management. Algorithms for diagnosis and management of functional dyspepsia were added.

CONCLUSIONS

  This consensus developed by Asian experts shows distinctive features of functional dyspepsia in Asia and will provide a guide to the diagnosis and management of functional dyspepsia for Asian primary care physicians.

Asian consensus report on functional dyspepsia

BACKGROUND/AIMS

Environmental factors such as food, lifestyle and prevalence of Helicobacter pylori infection are widely different in Asian countries compared to the West, and physiological functions and genetic factors of Asians may also be different from those of Westerners. Establishing an Asian consensus for functional dyspepsia is crucial in order to attract attention to such data from Asian countries, to articulate the experience and views of Asian experts, and to provide a relevant guide on management of functional dyspepsia for primary care physicians working in Asia.

METHODS

Consensus team members were selected from Asian experts and consensus development was carried out using a modified Delphi method. Consensus teams collected published papers on functional dyspepsia especially from Asia and developed candidate consensus statements based on the generated clinical questions. At the first face-to-face meeting, each statement was reviewed and e-mail voting was done twice. At the second face-to-face meeting, final voting on each statement was done using keypad voting system. A grade of evidence and a strength of recommendation were applied to each statement according to the method of the GRADE Working Group.

RESULTS

Twenty-nine consensus statements were finalized, including 7 for definition and diagnosis, 5 for epidemiology, 9 for pathophysiology and 8 for management. Algorithms for diagnosis and management of functional dyspepsia were added.

CONCLUSIONS

This consensus developed by Asian experts shows distinctive features of functional dyspepsia in Asia and will provide a guide to the diagnosis and management of functional dyspepsia for Asian primary care physicians.

Dyspepsia: organic versus functional

Dyspepsia is the medical term for difficult digestion. It consists of various symptoms in the upper abdomen, such as fullness, discomfort, early satiation, bloating, heartburn, belching, nausea, vomiting, or pain. The prevalence of dyspepsia in the western world is approximately 20% to 25%. Dyspepsia can be divided into 2 main categories: "organic" and "functional dyspepsia" (FD). Organic causes of dyspepsia are peptic ulcer, gastroesophageal reflux disease, gastric or esophageal cancer, pancreatic or biliary disorders, intolerance to food or drugs, and other infectious or systemic diseases. Pathophysiological mechanisms underlying FD are delayed gastric emptying, impaired gastric accommodation to a meal, hypersensitivity to gastric distension, altered duodenal sensitivity to lipids or acids, altered antroduodenojenunal motility and gastric electrical rhythm, unsuppressed postprandial phasic contractility in the proximal stomach, and autonomic nervous system-central nervous system dysregulation. Pathogenetic factors in FD are genetic predisposition, infection from Helicobacter pylori or other organisms, inflammation, and psychosocial factors. Diagnostic evaluation of dyspepsia includes upper gastrointestinal endoscopy, abdominal ultrasonography, gastric emptying testing (scintigraphy, breath test, ultrasonography, or magnetic resonance imaging), and gastric accommodation evaluation (magnetic resonance imaging, ultrasound, single-photon emission computed tomography, and barostat). Antroduodenal manometry can be used for the assessment of the myoelectrical activity of the stomach, whereas sensory function can be evaluated with the barostat, tensostat, and satiety test. Management of FD includes general measures, acid-suppressive drugs, eradication of H. pylori, prokinetic agents, fundus-relaxing drugs, antidepressants, and psychological interventions. This review presents an update on the diagnosis of patients presenting with dyspepsia, with an emphasis on the pathophysiological and pathogenetic mechanisms of FD and the differential diagnosis with organic causes of dyspepsia. The management of uninvestigated and FD, as well as the established and new pharmaceutical agents, is also discussed.

The role of eosinophils and mast cells in intestinal functional disease. Curr Gastroenterol Rep. 2011;13:323-330. [PMID: 21552990 DOI: 10.1007/s11894-011-0197-5]

Functional gastrointestinal disorders (FGIDs) are common and currently defined by a symptom-based classification with no discernable pathology. In functional dyspepsia (FD), the duodenum is now implicated as a key area where symptoms originate.This is attributed to immune activation with increasing evidence indicating a role for duodenal eosinophilia. In irritable bowel syndrome (IBS), mastocytosis has been documented throughout the small and large intestine. Eosinophils and mast cells are an important link between innate and adaptive immunity, and are important in allergic type TH2 inflammation. Eosinophils may give rise to symptoms due to release of preformed cytokine proteins, which trigger neural excitation, muscle spasm, and pain. The close relationship of mast cells to nerves in IBS may similarly give rise to symptoms. Genetic studies also support of the role of innate immunity in FGIDs. The data supporting a prime role for eosinophils and mast cells in subsets of FD and IBS has become credible, and these data should be used to implement advances in diagnosis and therapeutic trials.

Functional dyspepsia

PURPOSE OF REVIEW

This review summarizes the recent progress in the epidemiology, pathophysiology and treatment of functional dyspepsia.

RECENT FINDINGS

Epidemiological, pathophysiological and therapeutic studies continue to examine the Rome III-proposed subdivision of functional dyspepsia into epigastric pain syndrome and postprandial distress syndrome. Although epidemiological studies support the subdivision, studies in patient samples show major overlap. Several studies identified overlapping functional disorders and psychosocial comorbidity as major contributors to the severity of functional dyspepsia and its impact on quality of life. Central processing of visceral stimuli, and its role in the pathogenesis of functional dyspepsia, as well as low-grade inflammation in the duodenum are important emerging topics in pathophysiology research. Therapeutic studies have reported on prokinetic and fundus-relaxing drugs. Acotiamide is a first-in-class drug with both prokinetic and fundus-relaxing properties that was evaluated in the recent phase 2 and phase 3 trials in functional dyspepsia.

SUMMARY

There is gradual progress in our understanding of the symptom pattern, impact and pathophysiology of functional dyspepsia. The areas of recent advances including the recognition of low-grade duodenal inflammation, central nervous system processing and the exploration of novel pharmacotherapeutic approaches are summarized in this review.

Subjective food hypersensitivity: assessment of enterochromaffin cell markers in blood and gut lavage fluid

BACKGROUND

Food hypersensitivity is commonly suspected, but seldom verified. Patients with subjective food hypersensitivity suffer from both intestinal and extraintestinal health complaints. Abnormalities of the enterochromaffin cells may play a role in the pathogenesis. The aim of this study was to investigate enterochromaffin cell function in patients with subjective food hypersensitivity by measuring serum chromogranin A (CgA) and 5-hydroxytryptamine (5-HT, serotonin) in gut lavage fluid.

METHODS

Sixty-nine patients with subjective food hypersensitivity were examined. Twenty-three patients with inflammatory bowel disease and 35 healthy volunteers were included as comparison groups. CgA was measured in serum by enzyme-linked immunosorbent assay. Gut lavage fluid was obtained by administering 2 L of polyethylene glycol solution intraduodenally. The first clear fluid passed per rectum was collected and 5-HT was analyzed by liquid chromatography tandem mass spectrometry.

RESULTS

Serum levels of CgA were significantly lower in patients with subjective food hypersensitivity than in healthy controls (P = 0.04). No differences were found in 5-HT levels in gut lavage fluid between patients with subjective food hypersensitivity and the control groups. There was no correlation between serum CgA and gut lavage 5-HT.

CONCLUSION

Decreased blood levels of CgA suggest neuroendocrine alterations in patients with subjective food hypersensitivity. However, 5-HT levels in gut lavage fluid were normal.

Helicobacter pylori and nonmalignant diseases

Research published over the past year has documented the continued decline of Helicobacter pylori-related peptic ulcer disease and increased recognition of non-H. pylori, non-steroidal anti-inflammatory drugs ulcer disease--idiopathic ulcers. Despite reduced prevalence of uncomplicated PUD, rates of ulcer complications and associated mortality remain stubbornly high. The role of H. pylori in functional dyspepsia is unclear, with some authors considering H. pylori-associated nonulcer dyspepsia a distinct organic entity. There is increasing acceptance of an inverse relationship between H. pylori and gastroesophageal reflux disease (GERD), but little understanding of how GERD might be more common/severe in H. pylori-negative subjects. Research has focused on factors such as different H. pylori phenotypes, weight gain after H. pylori eradication, and effects on hormones such as ghrelin that control appetite.

Epidemiology of uninvestigated and functional dyspepsia in Asia: facts and fiction

Dyspepsia is a syndrome consisting of epigastric pain, burning, fullness, discomfort, early satiety, nausea, vomiting and belching. Functional dyspepsia (FD) is diagnosed if upper gastrointestinal endoscopy does not show structural abnormality explaining these symptoms. 8%-30% and 8%-23% of Asian people suffer from of uninvestigated dyspepsia and FD, respectively. Most patients with uninvestigated dyspepsia are found to have FD. Patients with FD are usually young and there is no predilection to any gender. Overlap of FD with other functional bowel diseases such as irritable bowel syndrome and gastroesophageal reflux disease is common in Asia. Cultural difference in reporting of symptoms of dyspepsia is well-known. Moreover, dietary factors, socio-cultural and psychological issues, gastrointestinal infection including that caused by Helicobacter pylori, frequency of organic diseases such as peptic ulcer and gastric cancer responsible for dyspeptic symptoms in the study population may also influence epidemiology of dyspepsia. There is considerable heterogeneity in the above issues among different Asian countries. More studies on epidemiology of FD are needed in Asia.

Functional dyspepsia, H. pylori and post infectious FD

BACKGROUND

Functional dyspepsia has been defined by Rome III as the presence of one or more chronic dyspepsia symptoms in the absence of any organic, systemic, or metabolic disease that is likely to explain the symptoms. Delayed gastric emptying, antral hypomotility and altered intestinal motility, decreased gastric accommodation, H.pylori infection, enhanced visceral sensitivity, abnormal duodenal sensitivity to acid, carbohydrate maldigestion and psychological factors have all been identified in subgroups of patients with functional dyspepsia. RELATIONSHIP BETWEEN H.PYLORI, FD AND POST INFECTIOUS FD:  The relationship between H. pylori infection and functional dyspepsia is controversial. H.pylori infection is present in a minority of patients with FD. Symptoms and abnormalities of function such as gastric emptying have not been consistently shown to be related to H.pylori infection. However, meta-analysis has shown that H.pylori eradication therapy in FD results in a small but statistically significant effect in H.pylori positive FD (relative risk reduction 10%). Guidelines for Helicobacter pylori infection have therefore strongly recommended H.pylori eradication therapy in H.pylori positive FD patients. Post-infectious dyspepsia has been described as a distinct clinical entity, based on a large retrospective study that showed a subset of dyspeptic patients who had a history suggestive of post-infectious dyspepsia. In a prospective study, investigators in Spain have found that development of dyspepsia was increased fivefold at 1 year after acute Salmonella gastroenteritis. In post-infectious FD patients, early satiety, weight loss, nausea, and vomiting are frequently reported together with a higher prevalence of impaired gastric accommodation. More recently, infectious FD has been found to be associated with persisting focal T-cell aggregates, decreased CD4+ cells and increased macrophage counts in the duodenum for several moths after acute infection. This suggests impaired ability of the immune system to terminate the inflammatory response after acute insult.

CONCLUSION

In conclusion, H. pylori infections, as well as other gut infections, have been associated with a subset of FD patients. Treatment of underlying infections can potentially lead to improvement in this group of patients.

Diagnosis and treatment of functional gastrointestinal disorders in the Asia-Pacific region: a survey of current practices

BACKGROUND AND AIMS

Functional gastrointestinal disorders (FGIDs), namely functional dyspepsia (FD) and irritable bowel syndrome (IBS) are common disorders important to public health in the Asia-Pacific region. Our objectives were to determine the current practices in diagnosis and management of these disorders in the Asia-Pacific region.

METHODS

Forty-three physicians and researchers in FGID who attended the first Asian Pacific Topic Conference at Tokyo in November 2010 were invited to answer a questionnaire. Twenty-three Japanese doctors and twenty doctors from other Asia-Pacific Societies answered the questionnaire, which consisted of 60 multiple-choice questions concerning physician's preferences in diagnosis and management of FGIDs.

RESULTS

Overall, there were similarities in diagnostic approach, such as differential diagnosis, exclusion of organic diseases, psychophysiological assessment, medical advice or medication with psychological drugs, not only among different Asia-Pacific region but also between FD and IBS. Several notable differences were seen. For example, general practitioners did not commonly use the term FD or diagnose FD by themselves, while the term IBS was widely used and frequently diagnosed. Sub-categorization was more common in IBS than FD. There was also a difference between Japan and other Asia-Pacific region; upper GI endoscopy and blood examination were more common in Japan, while eradication of Helicobacter pylori was more frequently done in other countries. Anti-secretory drugs for FD and mild laxatives or anti-diarrheal drug for IBS were frequently used, and prokinetics were used for all patients with FD or IBS. Interestingly, drugs developed in Japan and Chinese herbal medicines were more frequently prescribed in Japan.

CONCLUSION

Information obtained in this survey is useful for understanding the most common clinical approaches for FGIDs in the Asia-Pacific region.