The overlap of atopy and functional gastrointestinal disorders among 23,471 patients in primary care

Postprandial symptoms in disorders of gut-brain interaction and their potential as a treatment target

Postprandial, or meal-related, symptoms, such as abdominal pain, early satiation, fullness or bloating, are often reported by patients with disorders of gut-brain interaction, including functional dyspepsia (FD) or irritable bowel syndrome (IBS). We propose that postprandial symptoms arise via a distinct pathophysiological process. A physiological or psychological insult, for example, acute enteric infection, leads to loss of tolerance to a previously tolerated oral food antigen. This enables interaction of both the microbiota and the food antigen itself with the immune system, causing a localised immunological response, with activation of eosinophils and mast cells, and release of inflammatory mediators, including histamine and cytokines. These have more widespread systemic effects, including triggering nociceptive nerves and altering mood. Dietary interventions, including a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols, elimination of potential food antigens or gluten, IgG food sensitivity diets or salicylate restriction may benefit some patients with IBS or FD. This could be because the restriction of these foods or dietary components modulates this pathophysiological process. Similarly, drugs including proton pump inhibitors, histamine-receptor antagonists, mast cell stabilisers or even tricyclic or tetracyclic antidepressants, which have anti-histaminergic actions, all of which are potential treatments for FD and IBS, act on one or more of these mechanisms. It seems unlikely that food antigens driving intestinal immune activation are the entire explanation for postprandial symptoms in FD and IBS. In others, fermentation of intestinal carbohydrates, with gas release altering reflex responses, adverse reactions to food chemicals, central mechanisms or nocebo effects may dominate. However, if the concept that postprandial symptoms arise from food antigens driving an immune response in the gastrointestinal tract in a subset of patients is correct, it is paradigm-shifting, because if the choice of treatment were based on one or more of these therapeutic targets, patient outcomes may be improved.

Prevalence of functional gastrointestinal disorders in Saudi infants and toddlers: A cross-sectional multicenter study

BACKGROUND

Functional gastrointestinal disorders (FGIDs) are common pediatric problems, but their prevalence in Saudi Arabia is unknown. We aimed to assess the prevalence of FGIDs and risk factors among children in six regions of Saudi Arabia.

METHODS

This was a cross-sectional multicenter study enrolling children aged 0-48 months, attending pediatric clinics. Questionnaires evaluated the clinical history, symptoms, and sociodemographic information. FGIDs were defined according to Rome IV criteria.

RESULTS

The study involved 1011 infants and toddlers (mean [standard deviation (SD)] aged, 21.7 [19.4] months; FGIDs and mean [SD] age 17.4 [16.4] months; controls). FGIDs were diagnosed in 483 (47.7%) of all infants and toddlers. The prevalence of FGIDs was significantly higher in children aged 0-12 months than in those aged 13-48 months ( P < 0.001). The most common disorders were functional regurgitation (13.8%) in infants and functional constipation (9.6%) in toddlers. Univariate regression analysis confirmed that the rate of FGIDs was higher in term gestational age infants (odds ratio (OR) 2.7; 95% confidence interval (CI), 1.76-4.17, P < 0.001), in partial breastfeeding (OR 0.58; 95% CI, 0.40-0.84, P = 0.003), in formula feeding (OR 2.25; 95% CI, 1.51-3.35, P < 0.001), and in subjects with no history of food allergy (OR 2.40; 95% CI, 1.58-3.64, P < 0.001).

CONCLUSIONS

FGIDs are common in Saudi infants and toddlers (47.7%). Regurgitation is most prevalent in infants, and functional constipation is most common in toddlers. Term gestational age infant, partial breastfeeding, formula feeding, and subjects with no history of food allergy are associated with the prevalence of FGIDs.

Multimorbidity of Allergic Diseases Is Associated With Functional Gastrointestinal Disorders in a Young Japanese Population

Background/Aims

Although certain allergic diseases have been reported to be associated with the prevalence of functional dyspepsia (FD) and irritable bowel syndrome (IBS), it is unclear whether the presence of multiple allergic diseases further increases the prevalence of FD and IBS. The aim of this study is to determine this issue in young people.

Methods

A cohort of 8923 Japanese university students was enrolled and diagnoses of FD and IBS were confirmed using Rome III criteria. Allergic disorders diagnosed at medical institutions were obtained by means of a self-administered questionnaire.

Results

The prevalence of FD, IBS, and their overlap was found to be 1.9%, 6.5%, and 1.1%, respectively. Pollen allergy was independently positively correlated with FD, IBS, and overlap of FD and IBS. Allergic rhinitis was positively linked to IBS. Drug allergy was positively associated with FD. The presence of multiple allergic diseases was positively correlated with FD and IBS (FD: adjusted OR for 2 allergic diseases: 1.95 [95% CI, 1.24-2.98], P for trend = 0.003; and IBS: adjusted OR for 1 allergic disease: 1.40 [95% CI, 1.15-1.69], 2 allergic diseases 1.47 [95% CI, 1.12-1.91], and 3 or more allergic diseases: 2.22 [95% CI, 1.45-3.28], P for trend = 0.001). Additionally, the concomitant existence of multiple allergic diseases was also demonstrated to have a trend that correlated with the overlap of FD and IBS (P for trend = 0.018).

Conclusion

Allergic disease multimorbidity is positively correlated with the prevalence of FD and IBS in a young population.

A Minority of Childhood Disorders of Gut-Brain Interaction Persist Into Adulthood: A Risk-Factor Analysis

INTRODUCTION

Disorders of gut-brain interaction (DGBIs) may originate in childhood. There are currently limited data on persistence of DGBI into adulthood and risk factors for persistence. Furthermore, there are no data on this question from general practice, where the majority of DGBIs are diagnosed and managed. This study documents the proportion of childhood-diagnosed DGBIs that persisted into adulthood and what factors were associated with persistence.

METHODS

General practice records were obtained for more than 60,000 patients whose medical record spanned both childhood and adulthood years. Patients with diagnosed organic gastrointestinal disorder were excluded. Medical records were also interrogated for potential risk factors.

RESULTS

Eleven percent of patients with irritable bowel syndrome (IBS) and 20% of patients with functional dyspepsia (FD) diagnosed in childhood had repeat diagnoses of the same condition in adulthood. Female sex (odds ratio [OR] 2.02) was associated with persistence for IBS, while a childhood diagnosis of gastritis (OR 0.46) was risk-protective. Childhood non-steroidal anti-inflammatory drug use (OR 1.31, 95% confidence interval [CI] 1.09-1.56) was a risk factor for persistence in IBS. For FD, a childhood diagnosis of asthma (OR 1.30, 95% CI 1.00-1.70) was a risk factor, as was anxiety for both IBS (OR 1.24, 95% CI 1.00-1.54) and FD (OR 1.48 95% CI 1.11-1.97) with a similar finding for depression for IBS (OR 1.34, 95% CI 1.11-1.62) and FD (OR 1.88 95% CI 1.47-2.42).

DISCUSSION

Childhood DGBIs persist into adulthood in 10%-20% of patients, suggesting that management monitoring should continue into adulthood. Those diagnosed with anxiety or mood disorders in childhood should receive particular attention, and prescription of non-steroidal anti-inflammatory drugs in children should be made judiciously.

Risk factors associated with functional esophageal disorders (FED) versus gastroesophageal reflux disease (GERD)

INTRODUCTION

Despite the high prevalence of typical symptoms of gastroesophageal reflux disease (GERD), approximately 30% of patients have functional esophageal disorders (FED) on ambulatory reflux monitoring, which may include reflux hypersensitivity (RH; defined as physiologic acid exposure but temporally correlated symptoms of reflux), or functional heartburn (FH; defined as physiologic acid exposure and negative symptom correlation). There are limited epidemiological data characterizing these conditions. We investigated demographic and socioeconomic factors as well as medical comorbidities which may predispose to FED versus pathologic GERD.

METHODS

Adult patients with reflux symptoms for at least 3 months were studied with 24-h pH-impedance testing from 11/2019 to 3/2021. Participants were categorized into pathologic GERD, FH, or RH using pH-impedance data and reported symptom correlation. Demographic data, including age, gender, race/ethnicity, zip code, insurance status, and medical comorbidity data were retrospectively retrieved from the electronic medical record on all participants.

RESULTS

229 patients were included. Non-Hispanic Asian ethnicity (OR 5.65; p = 0.01), underweight BMI (OR 7.33; p = 0.06), chronic pain (OR 2.33; p < 0.01), insomnia (OR 2.83; p = 0.06), and allergic rhinitis (OR 3.90; p < 0.01) were associated with a greater risk for FED. Overweight BMI (OR 0.48; p = 0.03) and alcohol use (OR 0.57; p = 0.06) were associated with a decreased risk for FED.

DISCUSSION

This is the first report of a greater risk of FED in patients with underweight BMI, insomnia, chronic pain, allergic rhinitis, or of Asian or Hispanic ethnicities. The weak associations between female gender and anxiety are corroborated in other studies. Our findings enable clinicians to better screen patients with reflux for this disorder.

Ayurvedic clinical decision-making methods to predict, prevent and manage childhood allergic disorders

Allergy is a conundrum lacking satisfactory answers despite its global prevalence. Traditional systems of medicine may contain sustainable and effective solutions for the same. For mainstreaming them, an evaluation based on the system's own methods is inevitable rather than symptom-based correlations. Atopy is a novel entity in Ayurveda, but the methods of tripartite delineation (disease pattern, disease targets and influencing factors) of novel diseases and multifactorial approach to diagnosis and management in Ayurveda can bring about comprehensiveness in collection and categorization of data regarding the entity. This in turn can make the prediction, prevention and management of the same more precise, effective and sustainable. The article provides a template for the application of Ayurvedic biological framework in the diagnosis and management of novel diseases, with special reference to childhood allergic disorders.

Inhibited postprandial retrograde cyclic motor pattern in the distal colon of patients with diarrhea-predominant irritable bowel syndrome

Patients with irritable bowel syndrome (IBS) have recurrent lower abdominal pain, associated with altered bowel habit (diarrhea and/or constipation). As bowel habit is altered, abnormalities in colonic motility are likely to contribute; however, characterization of colonic motor patterns in patients with IBS remains poor. Utilizing fiber-optic manometry, we aimed to characterize distal colonic postprandial colon motility in diarrhea-predominant IBS. After an overnight fast, a 72-sensor (spaced at 1-cm intervals) manometry catheter was colonoscopically placed to the proximal colon, in 13 patients with IBS-D and 12 healthy adults. Recordings were taken for 2 h pre and post a 700 kcal meal. Data were analyzed with our two developed automated techniques. In both healthy adults and patients with IBS-D, the dominant frequencies of pressure waves throughout the colon are between 2 and 4 cycles per minute (cpm) and the power of these frequencies increased significantly after a meal. Although these pressure waves formed propagating contractions in both groups, the postprandial propagating contraction increase was significantly smaller in patients compared with healthy adults. In healthy adults during the meal period, retrograde propagation between 2 and 8 cpm was significantly greater than antegrade propagation at the same frequencies. This difference was not observed in IBS-D. Patients with IBS-D show reduced prevalence of the retrograde cyclic motor pattern postprandially compared with the marked prevalence in healthy adults. We hypothesize that this reduction may allow premature rectal filling, leading to postprandial urgency and diarrhea.NEW & NOTEWORTHY Compared with healthy adults this study has shown a significant reduction in the prevalence of the postprandial retrograde cyclic motor pattern in the distal colon of patients with diarrhea-predominant irritable bowel syndrome. We hypothesize that this altered motility may allow for premature rectal filling which contributes to the postprandial urgency and diarrhea experienced by these patients.

Prevalence of Functional Gastrointestinal Disorders (Rome IV Criteria) among a Cohort of New Zealand Children

Functional gastrointestinal disorders (FGIDs) are characterised by recurring gastrointestinal symptoms that are not secondary to organic disease. FGIDs may cause reduced quality of life, with approximately 22% of children experiencing at least one FGID. This study aimed to assess FGID prevalence among children attending a tertiary care hospital in New Zealand (NZ). Methods: Children aged ≥ four years were prospectively recruited from Christchurch Hospital, NZ. Data were collected on demographics, medical history, gastrointestinal symptoms (Rome IV), and quality of life (EQ-5D-Y). An analysis was carried out using analysis of variance and the chi-squared test of independence. Results: The cohort included 156 children, with a mean age of 9.5 years (SD 3.3), 56% male. According to the Rome IV criteria, 29% experienced at least one FGID, most commonly functional constipation and functional dyspepsia. FGID symptoms were associated with Māori ethnicity (p = 0.012) and parental FGID (p < 0.001). Quality of life was lower in the FGID group in the domain ‘Feeling worried, sad, or unhappy’ (p = 0.002). Conclusion: the association of FGIDs with worse quality of life, in particular relating to worry and sadness, should highlight the importance of providing support to school age children experiencing FGID symptoms.

Overlap of disorders of gut-brain interaction: a systematic review and meta-analysis

BACKGROUND

Rome criteria differentiate distinct types of disorders of gut-brain interaction (DGBI); also known as functional gastrointestinal disorders. Overlap of symptom categories frequently occurs. This systematic review and meta-analysis aimed to define the prevalence of DGBI overlap and compare overlap in population-based, primary care or tertiary care health settings. Furthermore, we aimed to compare symptom severity of psychological comorbidities in DGBI with and without overlap.

METHODS

For this systematic review and meta-analysis we searched MEDLINE (PubMed) and Embase electronic databases from inception until March 1, 2022, for original articles and conference abstracts of observational cross-sectional, case-controlled, or cohort design studies that reported the prevalence of DGBI overlap in adult participants (aged ≥18 years). We included only those studies where the diagnosis of DGBI was based on clinical assessment, questionnaire data, or specific symptom-based criteria. Studies were excluded if reporting on mixed populations of DGBI and organic diseases. Aggregate patient data were extracted from eligible published studies. The prevalence of DGBI overlap in all studies was pooled using the DerSimonian and Laird random effects model, and further analysis stratified by subgroups (care setting, diagnostic criteria, geographic region, and gross domestic product per capita). We also assessed the relationship between DGBI overlap with anxiety, depression, and quality of life symptom scores. This study was registered with PROSPERO (CRD42022311101).

FINDINGS

46 of 1268 screened studies, reporting on 75 682 adult DGBI participants, were eligible for inclusion in this systematic review and meta-analysis. Overall, 24 424 (pooled prevalence 36·5% [95% CI 30·7 to 42·6]) participants had a DGBI overlap, with considerable between-study heterogeneity (I²=99·51, p=0·0001). In the tertiary health-care setting, overlap among participants with DGBI was more prevalent (8373 of 22 617, pooled prevalence 47·3% [95% CI 33·2 to 61·7]) compared with population-based cohorts (11 332 of 39 749, pooled prevalence 26·5% [95% CI 20·5 to 33·4]; odds ratio 2·50 [95% CI 1·28 to 4·87]; p=0·0084). Quality of life physical component scores were significantly lower in participants with DGBI overlap compared with participants without overlap (standardised mean difference -0·47 [95% CI -0·80 to -0·14]; p=0·025). Participants with DGBI overlap had both increased symptom scores for anxiety (0·39 [95% CI 0·24 to 0·54]; p=0·0001) and depression (0·41 [0·30 to 0·51]; p=0·0001).

INTERPRETATION

Overlap of DGBI subtypes is frequent, and is more prevalent in tertiary care settings and associated with more severe symptom manifestations or psychological comorbidities. Despite the large sample size, the comparative analyses revealed substantial heterogeneity, and the results should be interpreted with caution.

FUNDING

National Health and Medical Research Council and Centre for Research Excellence.

Type 2 and type 17 effector cells are increased in the duodenal mucosa but not peripheral blood of patients with functional dyspepsia

Background

Functional dyspepsia is characterised by chronic symptoms of post-prandial distress or epigastric pain not associated with defined structural pathology. Increased peripheral gut-homing T cells have been previously identified in patients. To date, it is unknown if these T cells were antigen-experienced, or if a specific phenotype was associated with FD.

Objective

This study aimed to characterise T cell populations in the blood and duodenal mucosa of FD patients that may be implicated in disease pathophysiology.

Methods

We identified duodenal T cell populations from 23 controls and 49 Rome III FD patients by flow cytometry using a surface marker antibody panel. We also analysed T cell populations in peripheral blood from 37 controls and 61 patients. Where available, we examined the number of duodenal eosinophils in patients and controls.

Results

There was a shift in the duodenal T helper cell balance in FD patients compared to controls. For example, patients had increased duodenal mucosal Th2 populations in the effector (13.03 ± 16.11, 19.84 ± 15.51, p=0.038), central memory (23.75 ± 18.97, 37.52 ± 17.51, p=0.007) and effector memory (9.80±10.50 vs 20.53±14.15, p=0.001) populations. Th17 populations were also increased in the effector (31.74±24.73 vs 45.57±23.75, p=0.03) and effector memory (11.95±8.42 vs 18.44±15.63, p=0.027) subsets. Peripheral T cell populations were unchanged between FD and control.

Conclusion

Our findings identify an association between lymphocyte populations and FD, specifically a Th2 and Th17 signature in the duodenal mucosa. The presence of effector and memory cells suggest that the microinflammation in FD is antigen driven.

Immune Responses at Host Barriers and Their Importance in Systemic Autoimmune Diseases

Host barriers such as the skin, the lung mucosa, the intestinal mucosa and the oral cavity are crucial at preventing contact with potential threats and are populated by a diverse population of innate and adaptive immune cells. Alterations in antigen recognition driven by genetic and environmental factors can lead to autoimmune systemic diseases such rheumatoid arthritis, systemic lupus erythematosus and food allergy. Here we review how different immune cells residing at epithelial barriers, host-derived signals and environmental signals are involved in the initiation and progression of autoimmune responses in these diseases. We discuss how regulation of innate responses at these barriers and the influence of environmental factors such as the microbiota can affect the susceptibility to develop local and systemic autoimmune responses particularly in the cases of food allergy, systemic lupus erythematosus and rheumatoid arthritis. Induction of pathogenic autoreactive immune responses at host barriers in these diseases can contribute to the initiation and progression of their pathogenesis.

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.

Immune-mediated food reactions in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by recurrent abdominal pain and an altered defecation pattern. Depending on the criteria used, it affects between 5 and 10% of the general population and has a serious impact on quality of life. Most patients with IBS show an induction or exacerbation of their symptoms, particularly abdominal pain, after eating certain foods. This raises the question of the role played by food in IBS pathophysiology. In this review, we describe the multiple risk factors of IBS, and we give an overview of the role of food as a trigger of IBS, distinguishing between immune and non-immune reactions to food. We finally highlight recent findings identifying an immune-mediated mechanism underlying food-induced abdominal pain in IBS.

Overlap of heartburn, functional dyspepsia, and irritable bowel syndrome in a population sample: Prevalence, temporal stability, and associated comorbidities

BACKGROUND

Co-occurring (overlapping) irritable bowel syndrome (IBS), functional dyspepsia (FD), and heartburn has been observed. However, whether it is a distinct entity has not been established, nor what clinical, demographic, lifestyle, and psychological traits are associated with it. This study sought to estimate the prevalence and temporal stability of this overlap and to identify features specific to it in order to gain some insights into the potential etiopathogenesis.

METHODS

Two waves of a survey to a population-representative sample were conducted 3 years apart, recruiting 1312 individuals for this study. The chance-expected probability of complete overlap (CO) was calculated and compared with the observed CO. A range of demographic, lifestyle factors, medical diagnoses, sleep quality, and psychological distress were tested to identify predictors of overlap using logistic regression.

KEY RESULTS

CO was observed in 2.1% (95% confidence interval 1.9, 3.7) of the sample and was closely replicated in wave 2 at 2.0%. The observed CO was greater than expected by chance (0.2%) to a statistically significant extent (p < 0.001). Overlap between IBS subtypes, FD subtypes, and heartburn was also elevated above chance expectation. Individuals with CO were separately differentiated from others with respect to elevated rates of self-reported medically diagnosed asthma, elevated psychological distress score, and elevated impact on sleep quality. The discrimination provided by these factors was further independent of age and sex.

CONCLUSIONS AND INFERENCES

Overlap between IBS, FD, and heartburn (GERD) appears to be a distinct entity that has a profile including psychological morbidity, sleep disturbance, and elevated rates of atopy.

Functional gastrointestinal disorders are associated with capsaicin cough sensitivity in severe asthma

BACKGROUND

Although sensory nerve dysfunction is related to the pathology of severe uncontrolled asthma and functional gastrointestinal disorders (FGIDs), the impact of comorbid FGIDs on the pathophysiology of severe uncontrolled asthma remains poorly understood. The aim was to clarify the physiological relationships between severe uncontrolled asthma and FGIDs.

METHODS

Fifty-two patients with severe uncontrolled asthma who visited our hospital between September 2016 and August 2019 were retrospectively analyzed. Clinical characteristics, other comorbidities including gastroesophageal reflux disease (GERD), and biomarkers such as fractional nitric oxide (FeNO) and capsaicin cough sensitivity (C-CS) before the beginning of biologics or bronchial thermoplasty, were compared between patients with and without comorbid FGIDs. C-CS was evaluated by C5 (concentration of inhaled capsaicin that induced five or more coughs), and C5 ≤2.44 μM was defined as heightened C-CS.

RESULTS

Seventeen patients had comorbid FGIDs. These patients had a lower FeNO level (21.9 ± 1.7 ppb vs. 33.9 ± 2.8 ppb, P = 0.04), a lower C5 threshold (2.24 ± 2.88 μM vs. 8.91 ± 5.5 μM, P < 0.001), a higher prevalence of comorbid GERD (64.7% vs. 31.7%, P = 0.03), and a higher prevalence of heightened C-CS (70.6% vs. 28.6%, P = 0.007) than those without FGIDs. Analysis of covariance showed a significant effect of FGIDs on C-CS in severe uncontrolled asthma without being affected by GERD.

CONCLUSIONS

Comorbid FGIDs are associated with heightened C-CS in patients with severe uncontrolled asthma, and they may be an important extra-respiratory manifestation of the airway neuronal dysfunction phenotype of severe uncontrolled asthma.

Exploring the Differences in the Gut Microbiome in Atopic Dermatitis According to the Presence of Gastrointestinal Symptoms

(1) Background: Atopic dermatitis (AD) is a multifactorial chronic allergic skin disease. Gastrointestinal (GI) functions have been suggested to be associated with its incidence or severity. As modulators of the gut–skin axis, gut microbes might affect the pathophysiology of AD. (2) Methods: We divided a cohort of patients with AD according to their GI symptoms as follows: AD with epigastric fullness (ADwEF), AD with epigastric rigidity (ADwER), and AD without GI symptoms (ADw/oGI). The gut microbial profiles were analyzed using 16S rRNA amplicon sequencing. (3) Results: The microbiota of the ADwER group showed low diversity indices in richness and evenness and formed a separate cluster to the other groups. In the ADwER group, the proportion of Bacteroides increased, while that of Prevotella decreased; functional pathways related to phosphotransferase systems were not abundant relative to those in the ADw/oGI group. Taken together, patients with AD with GI symptoms have a different microbiome from patients with simple AD. (4) Conclusions: In an exploratory study aimed at evaluating the relationship between AD and GI symptoms, the gut microbiome in patients with AD with GI symptoms differed from that in patients with simple AD, and this result could serve as a basis for further gut–skin axis studies.

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.

Immune activation in irritable bowel syndrome: what is the evidence?

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder that is characterized by abdominal pain and an altered defecation pattern. It affects between 5 and 20% of the general population and can seriously impact quality of life. The pathophysiology of IBS is rather complex and multifactorial including, for example, altered signalling by the gut-brain axis, dysbiosis, abnormal visceral pain signalling and intestinal immune activation. The latter has gained particular interest in recent years, with growing insight into the bidirectional communication between the nervous system and the immune system. In this Review, we detail the current evidence suggesting that immune activation contributes to the pathology seen in patients with IBS and discuss the potential mechanisms involved. Moreover, we describe how immune mediators, particularly those released by mast cells, can directly activate or sensitize pain-transmitting nerves, leading to increased pain signalling and abdominal pain. Finally, we discuss the potential of interventions targeting immune activation as a new therapeutic strategy for patients suffering from IBS.

Colonic Mucosal Immune Activation in Mice with Ovalbumin-Induced Allergic Airway Disease: Association between Allergic Airway Disease and Irritable Bowel Syndrome

Recent studies on the pathophysiology of irritable bowel syndrome (IBS) have focused on the role of mast cells (MCs) in intestinal mucosal immunity. A link between allergic airway diseases (AADs) and IBS has been suggested because both diseases have similar pathophysiology. We aimed to investigate whether the induction of AAD in mice could lead to inflammation of the colonic mucosa, similar to IBS. We also evaluated whether this inflammatory response could be suppressed by administering a therapeutic agent. Mice were divided into three groups: control, AAD-induced, and salbutamol-treated. An AAD mouse model was established by intraperitoneal injection and nasal challenge with ovalbumin. Mice with AAD were intranasally administered salbutamol. Analyses of cytokine levels, MC count, and tryptase levels in the intestinal mucosa were performed to compare the changes in inflammatory responses among the three groups. Inflammation was observed in the intestinal mucosa of mice in the AAD group. This inflammation in AAD mice was suppressed after salbutamol treatment. Our study demonstrates that AAD induces an inflammatory response similar to that in IBS, suggesting a possible association between IBS and AADs. In patients with IBS with such allergic components, salbutamol may have the potential to alleviate the inflammatory response.

Prevalence, symptoms and risk factor profile of rumination syndrome and functional dyspepsia: a population-based study

BACKGROUND

Rumination syndrome is a functional gastroduodenal disorder characterised by effortless regurgitation of recently ingested food. Emerging evidence reports duodenal eosinophilic inflammation in a subset, suggesting a shared pathophysiology with functional dyspepsia (FD).

AIM

To assess the clinical features of rumination syndrome and FD in a community-based study.

METHODS

We mailed a survey assessing gastrointestinal symptoms, diet and psychological symptoms to 9835 residents of Olmsted County, MN, USA in 2017-2018; diagnostic codes were obtained from linked clinical records. The two disorders were assessed as mutually exclusive in 'pure' forms with a separate overlap group, all compared to a control group not meeting criteria for either. Prevalence of associations, and univariate and independent associations with predictors were assessed by logistic regression.

RESULTS

Prevalence of rumination syndrome and FD were 5.8% and 7.1%, respectively; the overlap was 3.83-times more likely than expected by chance. Independent predictors for rumination (odds ratio (OR), 95% confidence interval (CI)) were female gender (1.79, 1.21-2.63), smoking (1.89, 1.28-2.78), gluten-free diet (1.58, 1.14-2.19), allergic rhinitis (1.45, 1.01-2.08) and depression (1.10, 1.05-1.16). FD was independently associated with female gender, depression, non-coeliac wheat sensitivity, migraine, irritable bowel syndrome and somatic symptoms. A similar reported efficacy (≥54%) of low fat or dairy-free diets was found with both disorders (P = 0.53 and P = 1.00, respectively). The strongest independent associations with overlapping FD and rumination syndrome were a history of rheumatoid arthritis (3.93, 1.28-12.06) and asthma (3.02, 1.44-6.34).

CONCLUSION

Rumination syndrome overlaps with FD with a shared risk factor profile, suggesting a common pathophysiology.

Antibiotic use but not gastrointestinal infection frequently precedes first diagnosis of functional gastrointestinal disorders

INTRODUCTION

While the etiopathogenesis of functional gastrointestinal disorders (FGIDs) is not completely understood, alterations of the intestinal microbiome have been observed. Antibiotics can induce dysbiosis, but whether antibiotics are a risk factor for the onset of FGIDs is uncertain. Antibiotics have been reported as both a risk factor for new onset FGID but also as a therapy for existing FGID. This study aimed to estimate the fraction of cases where antibiotics provoked the onset of FGID.

METHOD

Electronic medical records were obtained from general practices (primary care) in the United Kingdom. Dates of antibiotic prescription (AP) were compared with first date of FGID diagnosis and contrasted across three prevalent FGIDs and controls without gastrointestinal disorders.

RESULTS

There were 10,926 GI healthy controls, 4326 IBS alone, 3477 FD alone, 340 chronic constipation and 4402 with overlap of multiple conditions. Both the prevalence of AP and rate were higher in FGID patients and increased with diagnosis of multiple FGIDs. 7%-14% of FGID patients were prescribed their first recorded antibiotic in the 12 months prior to their first FGID diagnosis and 20%-33% were prescribed an antibiotic in the same period. Differences between FGID groups were not accounted for by social deprivation and only rate of AP was moderated by social deprivation. In contrast, only 5%-10% of patients ever had a gastrointestinal infection recorded and only 1.5%-3.5% prior to their first FGID diagnosis.

CONCLUSION

These data indicate that antibiotics are prescribed prior to FGID diagnosis in a significant minority of care-seeking FGID patients, opening the potential for this medication to contribute to the pathophysiology. APs appears to mostly be for non-gastrointestinal conditions.

Perceived Gastrointestinal Symptoms and Association With Meals in a French Cohort of Patients With Irritable Bowel Syndrome

Background/Aims

The aim of our study is to evaluate the association between meals and perceived gastrointestinal symptoms in real life in a French cohort of irritable bowel syndrome (IBS) patients.

Methods

This prospective cross-sectional observational study included patients from the French association (association des patients souffrant du syndrome de l’intestin irritable [APSSII]) of IBS. Data were collected on demographics, IBS subtype, dietary food, and meal-induced gastrointestinal symptoms from patient filled self-questionnaires or questionnaires.

Results

Eighty-four patients with IBS were included; 82.3% female with a mean age of 46.9 ± 15.7 years. Each transit pattern subtype represented one-third of the population. Forty-five percent of patients had severe IBS according to IBS-Severity Scoring System; mean IBS Quality of Life score was 53.9 ± 18.3. Patients believed that food could trigger or exacerbate gastrointestinal symptoms in 73.3% and 93.4%, respectively. Eighty-nine percent had already tried diets, mostly lactose free diet and low fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols diet in 61.3% and 53.6% of cases. Thirty-nine percent of meals induced gastrointestinal symptoms. Meal-induced gastrointestinal symptoms were associated with severity and subtype but not with quality of life.

Conclusions

This study has confirmed the important link between gastrointestinal symptoms and food. Gastrointestinal symptoms induced by meals are frequent and associated with severity and IBS-diarrhea subtype. Our study also underlines patients’ interest in food and diet. More knowledge is needed on food that triggers IBS symptoms but also on diet conditions in order to improve this condition.

Duodenal eosinophilia and the link to anxiety: A population-based endoscopic study

INTRODUCTION

The concept of gut-to-brain communication via microbial or inflammatory pathways is gaining increased attention but genuine pathology directly linking gut perturbation to anxiety is lacking. We hypothesized that duodenal eosinophilia, as known to occur in functional dyspepsia (FD), may be an underlying cause of anxiety and may help explain the striking association between FD and anxiety.

METHODS

Randomly selected subjects from the national population register of Sweden completed the validated Abdominal Symptom Questionnaire; 1000 completed esophagogastroduodenoscopy and the Hospital Anxiety and Depression Scale questionnaire. Duodenal biopsies were obtained from 1^st (D1) and 2^nd portion (D2). Eligible subjects who underwent endoscopy (n = 887) were invited to participate in a 10-year follow-up study with the same questionnaires. Among endoscopy normal subjects, FD was identified by Rome criteria, and controls were symptom free. Duodenal eosinophilia was based on pre-defined cut-offs. Finding are reported as odds ratios (ORs) with 95% confidence interval and p-value.

RESULTS

The study population comprised 89 cases with FD and 124 healthy controls (mean age 62 years, SD 12, 34% male). Clinical anxiety at follow-up was elevated in those with D1 eosinophilia at baseline considering either new-onset anxiety (OR = 4.5, 95% CI 0.8, 23.8; p = 0.08) or follow-up anxiety adjusting for baseline anxiety (OR = 4.51 (95% CI 1.03, 19.81; p = 0.046).

CONCLUSION

Duodenal eosinophilia may potentially be a mechanism linked to anxiety independent of FD.

Allergy-related diseases in childhood and risk for abdominal pain-related functional gastrointestinal disorders at 16 years-a birth cohort study

BACKGROUND

Studies on allergy-related diseases in relation to abdominal pain-related functional gastrointestinal disorders (AP-FGIDs) in children are few and results are contradictory. We examined the associations between childhood allergy-related diseases and adolescent AP-FGIDs in general and irritable bowel syndrome (IBS) in particular.

METHOD

Prospective population-based birth cohort study of 4089 children born in Sweden 1994-1996. We analysed data from 2949 children with complete follow-up at 16 years (y) and no diagnosis of inflammatory bowel disease or coeliac disease at 12y or 16y. Asthma, rhinitis, eczema, and food hypersensitivity (FH) were assessed through questionnaires at 1-2y, 4y, 8y, 12y, and 16y. AP-FGIDs and IBS were assessed through questionnaires at 16y and defined according to the Rome III criteria. Associations between childhood allergy-related diseases and any AP-FGID and IBS and 16y respectively were examined using binomial generalized linear models with a log link function and described as relative risk with 95% confidence intervals.

RESULTS

The prevalence of any AP-FGID and IBS at 16y were 12.0% and 6.0% respectively. Eczema at 1-2y, 4y, and 8y, and FH at 12y and 16y were associated with an increased risk for any AP-FGID at 16y. Asthma and FH at 12y and 16y were associated with an increased risk for IBS at 16y. The relative risk for IBS at 16y increased with increasing number of concurrent allergy-related diseases at 16y, but linear trend for relative risk was only borderline statistically significant (P for trend = 0.05).

CONCLUSIONS

This prospective population-based study demonstrated positive associations between childhood allergy-related diseases and adolescent AP-FGIDs, including IBS, implicating shared pathophysiology among these disorders.

The frequency of and factors affecting functional gastrointestinal disorders in infants that presented to tertiary care hospitals

This study aimed to determine the prevalence of infantile functional gastrointestinal disorders (FGIDs) based on Rome IV diagnostic criteria, and to determine the associated patient demographic and nutritional characteristics. A total of 2383 infants aged 1-12 months which were evaluated by 28 general pediatricians and pediatric gastroenterologists on the same day at nine tertiary care hospitals around Istanbul, Turkey, between November 2017 and March 2018, were included in the study. Patients included consulted the pediatric outpatient clinics because of any complaints, but not for vaccines and/or routine well child follow-ups as this is not part of the activities in the tertiary care hospitals. The patients were diagnosed with FGIDs based on Rome IV diagnostic criteria. The patients were divided into a FGID group and non-FGID group, and anthropometric measurements, physical examination findings, nutritional status, risk factors, and symptoms related to FGIDs were evaluated using questionnaires. Among the 2383 infants included, 837 (35.1%) had ≥1 FGIDs, of which 260 (31%) had already presented to hospital with symptoms of FGIDs and 577 (69%) presented to hospital with other symptoms, but were diagnosed with FGIDs by a pediatrician. Infant colic (19.2%), infant regurgitation (13.4%), and infant dyschezia (9.8%) were the most common FGIDs. One FGID was present in 76%, and ≥2 FGIDs were diagnosed in 24%. The frequency of early supplementary feeding was higher in the infants in the FGID group aged ≤6 months than in the non-FGID group (P = 0.039).Conclusion: FGIDs occur quite common in infants. Since early diversification was associated with the presence of FGIDs, nutritional guidance and intervention should be part of the first-line treatment. Only 31% of the infants diagnosed with a FGID were presented because of symptoms indicating a FGID. What is Known: • The functional gastrointestinal disorders (FGIDs) are a very common disorder and affect almost half of all infants. • In infants, the frequency of FGIDs increases with mistakes made in feeding. When FGIDs are diagnosed in infants, nutritional support should be the first-line treatment. What is New: • This study shows that only a third of children presented to hospital because of the symptoms of FGIDs, but pediatricians were able to make the diagnosis in suspected infants after appropriate evaluation. • The early starting of complementary feeding (<6 months) is a risk factor for the development of FGIDs.

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.

Influence of constipation on atopic dermatitis: A nationwide population-based cohort study in Taiwan

BACKGROUND

Atopic dermatitis (AD) is the chronic inflammatory disorder that affects both in childhood and adulthood. Mounting evidence indicates that gut dysbiosis contributes to AD via the gut-skin axis. Constipation can result in alteration of the gut microflora. The clinical impact of constipation on AD has not been researched. Therefore, we aim to assess the risk of AD in constipated patients by the population-based cohort study.

METHODS

We collected 85 554 constipated people and 85 554 people without constipation between 1999 and 2013 from the Taiwanese National Health Insurance Research Database. Propensity score analysis was administrated to match age, gender, comorbidities and medications at a ratio of 1:1. Multiple Cox regression analysis was utilised to evaluate the adjusted hazard ratio of AD. In addition, sensitivity tests and a stratified analysis were conducted.

RESULTS

The incidence of AD was 4.9 per 1000 person-years in the constipation group, which was higher than the rate of 2.1 per 1000 person-years observed in the non-constipation group. After adjustment for age, gender, comorbidities, corticosteroids, antihistamine and antibiotics, constipated people had a 2.31-fold greater risk of AD compared with those without constipation (adjusted hazard ratio [aHR]: 2.31 (95% CI 2.17-2.46). Moreover, constipated people had a higher likelihood of AD, regardless of gender, comorbidities, as well as the usage of corticosteroids, antihistamines and antibiotics.

CONCLUSION

Constipation is associated with a significantly risk factor of AD. Clinicians should be careful of the possibility of AD in constipated people. Further study is warranted to investigate the possible pathological mechanisms of this relationship.

Impact of Diet on Symptoms of the Irritable Bowel Syndrome

Irritable bowel syndrome (IBS), with its key features of abdominal pain and disturbed bowel habit, is thought by both patients and clinicians to be strongly influenced by diet. However, the complexities of diet have made identifying specific food intolerances difficult. Eating disorders can masquerade as IBS and may need specialist treatment. While typical food allergy is readily distinguished from IBS, the mechanisms of gut-specific adverse reactions to food are only just being defined. These may include gut-specific mast cell activation as well as non-specific activation by stressors and certain foods. Visceral hypersensitivity, in some cases mediated by mast cell activation, plays a key part in making otherwise innocuous gut stimuli painful. Rapidly fermented poorly absorbed carbohydrates produce gaseous distension as well as short-chain fatty acids and lowering of colonic pH which may cause symptoms in IBS patients. Limiting intake of these in low FODMAP and related diets has proven popular and apparently successful in many patients. Existing diet, colonic microbiota and their metabolic products may be helpful in predicting who will respond. Wheat intolerance may reflect the fact that wheat is often a major source of dietary FODMAPs. It may also be either a forme fruste of coeliac disease or non-specific immune activation. Wheat exclusion can be successful in some of these patients. More research is needed to fully understand the mechanisms of food intolerances and how to best ameliorate them in a personalised medicine approach to diet in IBS.

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

Up to 20% of people worldwide develop gastrointestinal symptoms following a meal¹, leading to decreased quality of life, substantial morbidity and high medical costs. Although the interest of both the scientific and lay communities in this issue has increased markedly in recent years, with the worldwide introduction of gluten-free and other diets, the underlying mechanisms of food-induced abdominal complaints remain largely unknown. Here we show that a bacterial infection and bacterial toxins can trigger an immune response that leads to the production of dietary-antigen-specific IgE antibodies in mice, which are limited to the intestine. Following subsequent oral ingestion of the respective dietary antigen, an IgE- and mast-cell-dependent mechanism induced increased visceral pain. This aberrant pain signalling resulted from histamine receptor H₁-mediated sensitization of visceral afferents. Moreover, injection of food antigens (gluten, wheat, soy and milk) into the rectosigmoid mucosa of patients with irritable bowel syndrome induced local oedema and mast cell activation. Our results identify and characterize a peripheral mechanism that underlies food-induced abdominal pain, thereby creating new possibilities for the treatment of irritable bowel syndrome and related abdominal pain disorders.

Functional abdominal pain disorders and asthma: two disorders, but similar pathophysiology?

INTRODUCTION

Functional abdominal pain disorders (FAPDs) and asthma are common ailments affecting both children and adults worldwide. Multiple studies have demonstrated an association between these two disorders. However, the exact reason for this observed association is not apparent.

AREAS COVERED

The current review has explored available literature and outlined multiple underlying pathophysiological mechanisms, common to both asthma and FAPDs, as possible reasons for this association.

EXPERT OPINION

Smooth muscle dysfunction, hypersensitivity and hyper-responsiveness, mucosal inflammation, and barrier dysfunction involving gastrointestinal and respiratory tracts are the main underlying pathophysiological mechanisms described for the generation of symptoms in FAPDs and asthma. In addition, alterations in neuroendocrine regulatory functions, immunological dysfunction, and microbial dysbiosis have been described in both disorders. We believe that the pathophysiological processes that were explored in this article would be able to expand the mechanisms of the association. The in-depth knowledge is needed to be converted to therapeutic and preventive strategies to improve the quality of care of children suffering from FAPDs and asthma.

Constipation might be associated with risk of allergic rhinitis: A nationwide population-based cohort study

Background

Allergic rhinitis (AR) is a burdensome respiratory disorder whose etiology and pathophysiology remain controversial and most likely multifactorial. Accumulated evidence indicates that gut dysbiosis contributes to AR via the gut-airway axis. Constipation could result in alteration of the intestinal microflora. The clinical impact of constipation on AR has not been studied. We aimed to evaluate the risk of AR in constipated patients using a nationwide longitudinal population-based cohort.

Methods

We identified 57786 patients with constipation and 57786 matched controls between 1999 and 2013 from the Longitudinal Health Insurance Database, which is a subset of Taiwanese National Health Insurance Research Database. Propensity score analysis was used for matching age, sex, comorbidities, and medications at a ratio of 1:1. Multiple Cox regression and subgroup analyses were used to estimate the adjusted hazard ratio of AR.

Results

The incidence of AR was 32.2 per 1,000 person-years in constipated patients, which was twice that of non-constipated patients. After adjustment for patients’ age, gender, comorbidities, and medications, patients with constipation had a 2.3-fold risk of AR compared to those without constipation (adjusted hazard ratio [aHR]: 2.30; 95% CI, 2.23–2.37). In subgroup analyses, patients aged 20–39 years had a 2.24-fold higher risk of AR in the constipation cohort (aHR; 95% CI, 2.12–2.36). Patients aged <20, 40–64, and ≥65 years had a 2.09, 2.05, and 2.07-fold risk of AR in the constipation cohort, respectively (aHR; 95% CI, 1.98–2.20, 1.94–2.18, and 1.92–2.23). Also, patients with constipation had a higher likelihood of AR, regardless of sex, and with or without comorbidities including hyperlipidemia, hypertension, chronic kidney disease, chronic liver disease, diabetes, chronic obstructive pulmonary disease, rheumatoid arthritis, dyspepsia, irritable bowel syndrome, and anxiety.

Conclusion

Constipation might be associated with an increased risk of incidental AR. It seems that physicians should keep a higher index of suspicion for AR in people with constipation. The patency issue of gut could not be ignored in patients with AR.

Anxiety-related factors associated with symptom severity in irritable bowel syndrome

BACKGROUND

Gastrointestinal symptom-specific anxiety and somatization have both been associated with higher symptom severity in patients with irritable bowel syndrome (IBS); however, this relationship has not been explored fully. Moreover, the performance of the visceral sensitivity index (VSI) for measuring gastrointestinal symptom-specific anxiety has not been examined in a UK population. We conducted a cross-sectional survey to examine these issues.

METHODS

Gastrointestinal symptom-specific anxiety was measured using the VSI, and somatization was measured via the patient health questionnaire-12 (PHQ-12) in adults from the UK community with Rome IV-defined IBS. Exploratory factor analysis was performed on the VSI, prior to subsequent analyses, to establish its factor structure. Multiple regression analysis was used to determine the relationship between demographic features, different factors of the VSI, somatization, and IBS symptom severity.

KEY RESULTS

A total of 811 individuals with IBS provided complete data. Factor analysis of the VSI revealed a three-factor structure, accounting for 47% of the variance. The first of these VSI factors and the PHQ-12 were both strongly and independently associated with IBS symptom severity, for the group as a whole and for all four IBS subtypes. Most VSI items concerned with overt gastrointestinal symptom-specific anxiety loaded onto the other two VSI factors that were not associated with symptom severity.

CONCLUSIONS AND INFERENCES

The factor structure of the VSI requires further investigation. Our findings cast doubt on the central role of gastrointestinal symptom-specific anxiety as a driver for symptom severity in IBS. Awareness of both gastrointestinal and extra-intestinal symptoms, however, is strongly associated with symptom severity.

Atopic Patients Who Fulfilled Rome III Criteria for Irritable Bowel Syndrome Had Higher Animal Danders Sensitization

Background/Aims

The relationship between animal exposure and irritable bowel syndrome (IBS) is debated. Epidemiological studies have shown that atopy is more prevalent in IBS patients and vice versa. We set out to examine the association between animal danders sensitization and IBS-like symptoms in atopic patients.

Methods

We recruited 69 consecutive atopic patients from the allergy clinic of a tertiary hospital. Subjects completed validated bowel questionnaires, underwent skin prick test, blood was collected for serum total immunoglobulin E, and ImmunoCAP immune solid-phase allergen chip (ISAC) IgE multiplex assay.

Results

Twenty-eight (41.0%) atopic patients fulfilled the Rome III IBS criteria (atopy-IBS). There were no differences in gender, age, pet ownership, total serum IgE, or food allergen sensitization between atopy-IBS group and atopy-non-IBS group. We found that atopy-IBS group had significantly higher number of positive skin prick test for cat dander (64.3% vs 24.4%, P < 0.001), dog dander (64.3% vs 41.5%, P = 0.015) and weed pollens (32.1% vs 14.6%, P = 0.050) compared to atopy-non-IBS group. Out of 112 components from 51 allergen sources (both aeroallergen and food allergens), only Fel d1 (a major cat dander antigen) IgE is significantly higher in atopy-IBS group than atopy-non-IBS group (21.4% vs 2.4%, P = 0.029). Majority of atopy-IBS patients had mixed-type IBS.

Conclusions

We demonstrated an association between animal danders sensitization, in particular cat dander sensitization, and IBS-like symptoms in atopic patients. Future studies are needed to explore the relationship between aeroallergen and functional gastrointestinal disorders. Sensitization may be related to the pathophysiology of IBS or it could be that we are missing aeroallergen-induced gut allergy.

Duodenal inflammation: an emerging target for functional dyspepsia?

Introduction: Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders and is classified into postprandial distress and epigastric pain syndrome. Despite the recognition of duodenal inflammation as a potential trigger of symptoms, only limited anti-inflammatory therapies exist.Areas covered: This narrative review summarizes the recent advances in the pathophysiology and treatment of FD; it identifies potential therapeutic targets and gaps in the field. An electronic literature search was conducted in Pubmed up to 31st of December 2019.Expert opinion: There is compelling evidence for the role of duodenal inflammation and the eosinophil-mast cell axis in the pathogenesis of dyspeptic symptoms. Traditional prokinetic drugs and neuromodulators target gastric dysmotility and visceral hypersensitivity but are hampered by limited efficacy and side effects. Independent of acid suppression, the anti-inflammatory action of proton pump inhibitors, which remain the first-line therapy in FD, may also explain their therapeutic effect. Other existing and newly established anti-inflammatory drugs should be investigated while trials including probiotics and selective antibiotics should examine the host microbiome and immune activation. Targeted treatments for potential causes of duodenal pathology, such as impaired permeability and dysbiosis, are likely to emerge in the future.

Novel concepts in the pathophysiology and treatment of functional dyspepsia

Emerging data increasingly point towards the duodenum as a key region underlying the pathophysiology of functional dyspepsia (FD), one of the most prevalent functional GI disorders. The duodenum plays a major role in the control and coordination of gastroduodenal function. Impaired duodenal mucosal integrity and low-grade inflammation have been associated with altered neuronal signalling and systemic immune activation, and these alterations may ultimately lead to dyspeptic symptoms. Likely luminal candidates inducing the duodenal barrier defect include acid, bile, the microbiota and food antigens although no causal association with symptoms has been convincingly demonstrated. Recognition of duodenal pathology in FD will hopefully lead to the discovery of new biomarkers and therapeutic targets, allowing biologically targeted rather than symptom-based therapy. In this review, we summarise the recent advances in the diagnosis and treatment of FD with a focus on the duodenum.

Abdominal Pain in Children Develops With Age and Increases With Psychosocial Factors

BACKGROUND & AIMS

Functional gastrointestinal disorders are highly prevalent, cause significant suffering, and are costly to society. Pain is a central feature of 2 of the most common functional gastrointestinal disorders: irritable bowel syndrome and functional dyspepsia. Although these disorders have been well studied in adults, their etiology is poorly understood. We sought to identify early life factors associated with the development of abdominal pain in children (age, 2-12 y).

METHODS

We collected data from the All Babies in Southeast Sweden study of 1781 children, born from October 1, 1997, through October 31, 1999, whose families answered questions about abdominal pain and risk factors at birth, 1 year, 2.5 years, 5 years, 8 years, and 10 to 12 years. We used latent growth curve models to evaluate risk factors for development of abdominal pain. The primary outcomes were prevalence of abdominal pain and associated factors.

RESULTS

The prevalence of abdominal pain increased linearly with age in the study cohort, increasing by approximately 6% per year. Psychosocial variables associated with slope of the growth curve included lower emotional control at age 2 years (P = .005), parental concern for the child at age 2 years (P = .02), and measures of parental stress (P = .004). Nonvaginal birth was associated with a reduced slope of the growth curve (P = .03).

CONCLUSIONS

In a study of children in Sweden, we found early psychosocial environment and mode of delivery at birth was associated with development of childhood abdominal pain. Factors associated with development of the early immune system, identified in previous recall-based research, were not supported by data from this study. These findings have important implications for the prevention of abdominal pain in children and later in life.

The impact of allergic rhinitis on gastrointestinal disorders among young adults

BACKGROUND

An association between allergic rhinitis (AR) and digestive diseases (DDs) has been reported; however, studies have only focused on the prevalence of DDs in populations of patients with AR. In individuals with specific DDs, the impact of AR on the frequency of clinical visits for each DD has not been studied. Moreover, the association between topical steroid usage for AR and DDs has not been investigated.

METHODS

Data from 16 526 men and 18 438 women, aged 21 to 30 years, were collected from a national database. Individuals were separated into the AR and non-AR groups. Eight common DDs were studied: (1) gastroesophageal reflux disease (GERD), (2) gastritis and duodenitis, (3) peptic ulcers, (4) irritable bowel syndrome, (5) gastric functional disease, (6) intestinal functional disease, (7) gastroenteritis and colitis, and (8) constipation. The rate of each DD was compared between groups. In individuals with specific DDs, the frequency of clinical visits for each DD was also compared between groups. Between users and nonusers of topical steroids in the AR group, the rate of DDs was compared.

RESULTS

Significant associations were observed between all eight DDs and AR in both sexes. In comparison to the non-AR group, women with AR visited clinics more frequently for gastritis/duodenitis, gastric and intestinal functional disease, gastroenteritis/colitis, and constipation, while men with AR visited clinics more frequently for gastritis/duodenitis, gastric functional disease, gastroenteritis/colitis, and constipation. Female topical-steroid users with AR had higher rates of GERD, irritable bowel syndrome, gastric or intestinal functional disease, and gastritis/colitis. Male topical-steroid users with AR had higher rates of GERD and peptic ulcers.

CONCLUSION

AR was associated with DDs in both sexes. However, the influence of AR on clinical visit frequency varied among specific DD groups. Topical steroid usage for AR was associated with some DDs, but the association requires future evaluation.

What Causes Functional Gastrointestinal Disorders? A Proposed Disease Model

Chronic unexplained gastrointestinal symptoms impact more than 1 in 5 Americans and their families; these disorders include the irritable bowel syndrome (IBS) and functional dyspepsia (FD), currently classified by Rome IV as functional gastrointestinal disorders. By definition, IBS and FD have no established pathology, but emerging evidence suggests this paradigm may need revision. Immune activation and, in subsets, subtle intestinal pathology have been identified in FD (most notably, postprandial distress syndrome) and IBS-diarrhea. A disease model is proposed that accounts for all of the intestinal and extraintestinal symptoms, relationship to food and infection, and the overlap with gastroesophageal reflux disease. It is speculated that antigen presentation to the mucosa (e.g., microbial antigens or food proteins after acute gastroenteritis) induces, in a genetically primed host, immune activation of the intestine with low-grade intestinal inflammation and subsequently neuronal structural and functional alterations, producing regional intestinal hypersensitivity and motor dysfunction. Immune activation may explain the female predominance and fluctuations in immune activity for symptom variability over time. In the future, as further evidence accumulates, the management paradigm may potentially shift to objective pathology-based subtyping based on serological, microbiological, and clinical assessments to identify when targeted therapies should be deployed in subsets. Potential targeted interventions may include therapies to dampen down immune activation or block release of key mediators such as histamine, specific microbial targeted treatments that may reverse disease, and dietary advice to eliminate relevant food antigens after objective in vivo testing. Only by identifying causation can we eventually anticipate cure, and as the true pathology unravels in subsets, this may become a reality.

Chronic unexplained nausea in adults: Prevalence, impact on quality of life, and underlying organic diseases in a cohort of 5096 subjects comprehensively investigated

We evaluated to define the clinically significant chronic nausea in general population and to assess the prevalence of chronic unexplained nausea after exclusion of organic causes through the meticulous medical examination. Two phase studies were conducted. In phase 1, telephone survey was conducted to define the clinically significant nausea in 5000 representative subjects for a general population. Clinically significant nausea was identified by lowered quality of life if the frequency was 'more than one day per week'. Its prevalence was 1.6% (1.4-1.8%) and about 90% of nausea was not accompanied with vomiting. In phase 2, 5096 participants in a comprehensive health-screening cohort were enrolled. We investigated demographics, gastrointestinal symptoms, somatization symptoms and health related quality of life using validated questionnaire. All participants underwent meticulous medical examinations including endoscopy, abdominal ultrasound, thyroid function test, and blood testing. Among a total of 5096 subjects (men 51.8%, mean age 47.5 ± 10.0 years), organic diseases associated with chronic nausea were reflux esophagitis, duodenal ulcer and hyperthyroidism. The prevalence of chronic unexplained nausea was 0.6% (95% CI 0.4-0.8%) and there were significant overlap with functional dyspepsia and irritable bowel syndrome. HRQoL is significantly lower in people with nausea occurring 'more than one day per week' in a general population. Most chronic nausea was not accompanied with vomiting. Chronic unexplained nausea is uncommon affecting only 0.6% of the population but are more likely to report functional dyspepsia and irritable bowel syndrome.

Functional Dyspepsia in the Elderly

PURPOSE OF REVIEW

Functional dyspepsia is a common condition, and the condition is defined by symptoms using Rome IV criteria. This review addresses the issue of functional dyspepsia in elderly patients, epidemiology, investigation, and treatment.

RECENT FINDINGS

Recent studies show that while the prevalence of dyspepsia declines in the elderly, it is still prevalant investigations to confirm the diagnosis (including mandatory upper gastrointestinal endoscopy) must exclude organic disease. These include ulcers (particularly associated with nonsteroidal antiinflammatory drugs), Helicobacter pylori pathologies, cancer, coeliac disease, and autoimmune gastritis. Recent research is unraveling pathophysiology beyond symptom-only definitions, focusing on the duodenum with innate immune disturbance (duodenal eosinophilia) and microbial disruption as possible cause. Management of functional dyspepsia includes making a secure diagnosis, treatment with first-line proton pump inhibitors (PPI), then tricyclic antidepressants, and careful choice of prokinetics. Herbal treatments (peppermint oil) and STW-5 have in this age group limited efficacy. Further studies are needed to define the prevalence of functional dyspepsia in the elderly and of prime importance, to exclude organic disease as a cause for symptoms of dyspepsia.

Association between Irritable Bowel Syndrome and Allergic Diseases: To Make a Case for Aeroallergen

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease and the most common cause of prolonged abdominal pain and bowel disturbances in the developed world. While initially thought to be functional or psychosomatic in nature, IBS is now recognized as a heterogeneous group of conditions. A subset of IBS patients and patients with allergic diseases share some characteristic inflammatory features. In fact, atopic children show an increased likelihood of developing IBS as adults. Given these findings, a subset of IBS may be suffering from allergy-related gut diseases. In this review, we present the allergy-related comorbidities of IBS, including genetic, environmental, and immunologic factors. We discuss studies demonstrating an increased sensitization of IBS patients to aeroallergens compared to food allergens. We then postulate potential pathophysiological mechanisms underlying both IBS and aeroallergens in the gut, followed by potential implications in the screening and treatment of allergies in IBS patients.

Selected allergic diseases of the gastrointestinal tract

Clinical symptoms of food allergy may affect not only the digestive tract, but also the respiratory system, skin, or cardiovascular system. They may manifest themselves as gastrointestinal problems, asthma attacks, hives, or anaphylactic shock. Allergic reactions of the gastrointestinal tract may be IgE-independent (oral anaphylaxis syndrome, acute gastrointestinal reactions), mixed (eosinophilic gastrointestinal disorders), or IgE-independent (food-induced enterocolitis, proctitis, or enteropathy). The most serious conditions in which allergic background plays or can play an important role are: oral anaphylaxis syndrome, aphthous stomatitis, reflux disease, acute and chronic allergic reactions of gastric mucosa, irritable bowel syndrome, and eosinophilic gastrointestinal disorders.

Tangible pathologies in functional dyspepsia

Functional dyspepsia (FD) is a common, costly and complex disease, currently defined by symptoms, directed by the Rome consensus on functional bowel disorders, which has evolved over the past two decades. Symptoms include abdominal pain, are often meal related and there are two major subtypes, postprandial distress syndrome and epigastric pain syndrome, not attributed to pathology. Increasingly it is recognised that tangible pathologies occur in FD, for example Helicobacter pylori and other pathophysiological changes, most notably duodenal pathology, namely duodenal eosinophilia, permeability alterations, structural neuronal changes and microbial duodenal dysbiosis. This has led to the idea that FD is a true disease entity and triggers of this condition based on epidemiology studies point towards allergy, immune disorders and infection. Anxiety and depression may precede or follow FD, (brain-gut/gut-brain disorders). Currently most therapies for FD are inadequate but underlying pathology may lead to targeted treatment success as an attainable goal.

The association between functional dyspepsia and depression: a meta-analysis of observational studies

Concomitant functional dyspepsia (FD) and psychosocial stressors have been reported; however, the association between FD and depression remains controversial and no quantitative meta-analysis exists. Published articles were identified through a comprehensive review of PubMed, Embase, and Web of Science from inception to the 8 July 2018. The pooled odds ratios (ORs) with 95% confidence intervals and subgroup analyses were calculated using a random-effects model. Findings for a total of 59 029 individuals were pooled across 23 studies and examined. Our analyses showed a positive association between FD and depression, with an OR of 2.28 (95% confidence interval: 2.02-3.81; I=100%). In the subgroup analysis, FD patients in Europe (OR=6.19) were more likely to have depression compared with Asians (OR=2.47); the overall significance results decreased the most in subgroup which the overall significance of the subgroup analyses results decreased the most in studies that adjusted for BMI (OR=1.42). Our meta-analysis showed a positive association between FD and depression. Further large-scale prospective cohort studies are needed to investigate the causality between FD and depression.

Duodenal eosinophilia is associated with functional dyspepsia and new onset gastro-oesophageal reflux disease

BACKGROUND

It is unexplained why functional dyspepsia and gastro-oesophageal reflux disease (GERD) overlap more often than expected by chance. Post-prandial distress syndrome has been linked to impaired gastric fundic accommodation which may induce increased transient lower oesophageal sphincter relaxations and consequent GERD. Duodenal eosinophilia has been linked to functional dyspepsia and post-prandial distress syndrome.

AIM

To identify if there is an association between duodenal eosinophilia in functional dyspepsia and symptoms of GERD and whether post-prandial distress syndrome or epigastric pain syndrome are associated with new onset GERD.

METHODS

Participants (n = 1000) were randomly selected from the national Swedish population register and surveyed by questionnaires and oesophagogastroduodenoscopy in 1999-2001. All eligible subjects (n = 887) were invited to a follow-up study in 2010 (response rate 79%). In a case-control study of 213 subjects (functional dyspepsia vs healthy controls), histology from the duodenum was evaluated at baseline and the possible association of eosinophilia to new onset GERD symptoms was analysed.

RESULTS

Functional dyspepsia (OR 7.6; 95% CI 2.93-19.4, P < 0.001) and post-prandial distress syndrome at baseline (OR 9.0, 95% CI 3.36-24.0, P < 0.001) were associated with an increased risk of GERD at follow-up. Eosinophilia in the second part of duodenum only was independently associated with an increased risk of GERD amongst those with functional dyspepsia (OR 4.2; 95% CI 1.2-4.77, P = 0.024) and post-prandial distress syndrome at baseline (OR 6.0; 95% CI 1.50-23.6, P = 0.011), respectively.

CONCLUSIONS

Duodenal eosinophilia is associated with increased risk of GERD at 10-year follow-up in those with functional dyspepsia and post-prandial distress syndrome at baseline. Duodenal eosinophilia may explain the link between GERD and functional dyspepsia, suggesting subsets of functional dyspepsia and GERD may be part of the same disease spectrum.

Follow up on atopy and the gastrointestinal tract - a review of a common association 2018

Primary atopic disorders can be classified as heritable genetic disorders presenting with deregulated pathogenic allergic effector responses irrespective of sensitization. In the last decade, there are parallel rises in the burden of atopic and gastrointestinal (GI) diseases. Areas covered: There is increasing recognition of an association between atopy and GI disease through immune dysregulation, the microbiome and shared genetic pathways. Since the first article on atopy and the GI tract in 2014 in this journal, many more studies have shed light on the shared pathways in these diseases, particularly in the field of eosinophilic GI disease, functional GI disorders, and inflammatory bowel disease. Expert opinion: Understanding the links with common mechanisms in atopy and GI diseases that may lead to better targeting of treatment through manipulation of immune mechanisms, the microbiome, genetics, food allergens and specific GI diseases such as inflammatory bowel disease, functional GI disorders.