Proton Pump Inhibitors Reduce Duodenal Eosinophilia, Mast Cells, and Permeability in Patients With Functional Dyspepsia

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.

Determination of Optimal Eosinophil Thresholds for Diagnosis of Eosinophilic Gastritis and Duodenitis: A Pooled Analysis of 4 Prospective Studies

INTRODUCTION

Consensus is lacking regarding the number of eosinophils (eos) required for the diagnosis of eosinophilic gastritis (EoG) and eosinophilic duodenitis (EoD). In addition, thresholds that require multiple high-power fields (HPFs) may not be practical for clinical use, resulting in delayed or missed diagnoses. This pooled analysis of 4 prospective studies assessed thresholds for multiple and single HPFs used to diagnose EoG and EoD.

METHODS

Studies included the phase 2 ENIGMA1, the phase 3 ENIGMA2, an EoG/EoD prevalence study and a healthy volunteer study. Eos were quantified in the epithelium and lamina propria for controls and symptomatic participants. Symptomatic participants were further divided by histologic diagnosis of EoG/EoD. Peak eos counts were assessed, and the area under the receiver operating characteristic curve was analyzed to identify eos cutoffs for detection of EoG/EoD using the Youden index and sensitivity and specificity equality approaches.

RESULTS

Based on the highest specificity analysis in 740 patients, the optimal eos threshold was determined to be 20 eos/HPF in 5 gastric HPFs for EoG (71% sensitivity and 94% specificity) and 33 eos/HPF in 3 duodenal HPFs for EoD (49% sensitivity and 100% specificity). For single-field analysis, the optimal eos thresholds were 33 eos/HPF (EoG) and 37 eos/HPF (EoD), both corresponding to 93% sensitivity and 93% specificity.

DISCUSSION

Highly specific single gastric and duodenal HPF thresholds may have more clinical applicability than thresholds requiring multiple HPFs and could better facilitate development of practical histopathologic guidelines to aid pathologists and clinicians in the detection and diagnosis of EoG and/or EoD.

Association between dietary factors, symptoms, and psychological factors in adults with dyspepsia: A cross-sectional study

BACKGROUND

Evidence-based dietary management approaches for symptoms of dyspepsia are lacking. This study aimed to compare dietary factors, symptoms, quality of life (QOL) and salivary cortisol in dyspepsia participants and healthy controls.

METHODS

A cross-sectional survey was completed by adults with dyspepsia (n = 121) meeting Rome IV criteria and healthy controls (n = 52). Outcome measures included self-reported questionnaires about dietary habits, triggers, restrictions, dietary management approaches, nutritional intake, psychological variables, QOL, gastrointestinal symptoms, and optional cortisol awakening response (CAR) via saliva samples. Data were analyzed using Chi-square or Mann-Whitney U. Cortisol awakening response data was analyzed using moderated regression controlling for age, gender and distress.

KEY RESULTS

Fermentable carbohydrates (FODMAPs) (55%) were the most reported trigger in adults with dyspepsia. The dyspepsia group (88%) followed special diets more than controls (47%; p < 0.001), with a low FODMAP diet being most common (69%). The dyspepsia group consumed less fiber (p = 0.014), calcium (p = 0.015), and total FODMAPs (p < 0.001) than controls. There was a greater prevalence of comorbid anxiety (41%) and depression (31%) in dyspepsia compared to controls (15% and 12%, respectively, p < 0.001 and p = 0.006). The dyspepsia group had poorer QOL and greater gastrointestinal symptom severity than controls (p < 0.001). There was a negative association between anxiety and CAR (p = 0.001) in dyspepsia but not in controls.

CONCLUSIONS & INFERENCES

Adults with dyspepsia follow special diets more than controls and perceive FODMAPs as a key dietary trigger. These findings highlight the importance of monitoring nutritional adequacy and QOL, and emphasize mechanisms of depleted stress response in dyspepsia, warranting further exploration.

Radiation-induced gastric injury during radiotherapy: molecular mechanisms and clinical treatment

Radiotherapy (RT) has been the standard of care for treating a multitude of cancer types. Radiation-induced gastric injury (RIGI) is a common complication of RT for thoracic and abdominal tumors. It manifests acutely as radiation gastritis or gastric ulcers, and chronically as chronic atrophic gastritis or intestinal metaplasia. In recent years, studies have shown that intracellular signals such as oxidative stress response, p38/MAPK pathway and transforming growth factor-β signaling pathway are involved in the progression of RIGI. This review also summarized the risk factors, diagnosis and treatment of this disease. However, the root of therapeutic challenges lies in the incomplete understanding of the mechanisms. Here, we also highlight the potential mechanistic, diagnostic and therapeutic directions of RIGI.

Association between genetic polymorphisms of NOD1, Interleukin-1B, and cagA strain with low-grade duodenal eosinophilia in Helicobacter pylori-related dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a multifactorial disorder. Helicobacter pylori (H. pylori)-related dyspepsia (HpD) may be considered a separate entity. Duodenal eosinophilia is a potential pathogenic mechanism in FD. However, the impact of duodenal eosinophilia and host genetic polymorphism of innate and pro-inflammatory cascade, nucleotide-binding oligomerization domain 1 (NOD-1), and interleukin-1 beta (IL-1β) in HpD was not explored.

AIM

To evaluate the association of NOD1-796G>A and IL-1B-511C>T gene variants and low-grade duodenal eosinophilia in HpD.

METHODS

A multicenter cross-sectional study was conducted. A total of 253 patients who met Rome-IV criteria were selected before upper endoscopy and 98 patients were included after unremarkable upper endoscopy and positive H. pylori in gastric biopsies were assessed. Clinical parameters, H. pylori cagA and duodenal histology, were evaluated.

RESULTS

Sixty-four (65%) patients had epigastric pain syndrome (EPS), 24 (25%) postprandial distress syndrome (PDS), and 10 (10%) EPS/PDS overlap. FD subtypes were not associated with NOD1-796G>A and IL-1B-511C>T gene variants. Low-grade duodenal eosinophilia was significantly increased in NOD1-796 GG versus single A-allele, but not in IL-1B-511 single T-allele or CC-allele. This association is dependent of cagA infection, since harboring cagA strain was significantly associated with low-grade duodenal eosinophilia with isolated variants NOD1-796 GG and IL-1B-511 single T-allele, but not without cagA. When we performed combined polymorphism analysis with NOD1-796 GG/IL-1B-511 single T-allele, a synergistic effect on low-grade duodenal eosinophilia was found between these two loci irrespective of cagA strain status in HpD.

CONCLUSION

Our findings suggest that low-grade duodenal eosinophilia is significantly associated with NOD1-796 GG allele specially in cagA strain and with allelic combination NOD1-796 GG/IL-1B-511 single T-allele independent of cagA strain infection in HpD patients.

Improved Sleep Affects Epigastric Pain in Functional Dyspepsia by Reducing the Levels of Inflammatory Mediators

INTRODUCTION

The pathogenesis of epigastric pain in functional dyspepsia (FD) is complex. The study aims to explore the effect of sleep improvement on this symptom.

METHODS

In total, 120 patients with FD-associated epigastric pain and insomnia were randomly divided into experimental and control groups using the envelope method. After applying the exclusion criteria, 107 patients were enrolled in the experimental (56 patients) and control (51 patients) groups. Insomnia was graded according to the Pittsburgh Sleep Quality Index (PSQI). In the experimental group, eszopiclone 3 mg, eszopiclone 3 mg + estazolam 1 mg, and eszopiclone 3 mg + estazolam 2 mg were given to patients with mild, moderate, and severe insomnia, respectively. In the control group, patients were given 1, 2, or 3 tablets of vitamin B complex. Patient sleep quality was monitored with Sleepthing. Epigastric pain was evaluated with a Numeric Rating Scale. The serum levels of IL-1β, IL-6, IL-8, and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunosorbent assay. Pain scores, sleep parameters, and serum levels of inflammatory mediators were compared before and after treatment.

RESULTS

After treatment, the pain scores, sleep parameters, and TNF-α and IL-6 levels in the experimental group were significantly lower than those in the control group (p < 0.05). PSQI insomnia scores were significantly associated with pain scores, IL-6, and TNF-α (p < 0.05) but not in IL-8 and IL-1β levels (p > 0.05) among the three groups.

CONCLUSIONS

Improving sleep with eszopiclone and/or estazolam alleviates FD-associated epigastric pain, possibly by inhibiting related downstream transmission pathways and reducing the release of inflammatory mediators.

Functional Dyspepsia: Current Understanding and Future Perspective

BACKGROUND

Functional dyspepsia (FD) is a common disorder characterized by chronic or recurrent upper abdominal pain or discomfort without any structural abnormalities in the gastrointestinal tract. FD is categorized into two subgroups based on symptoms: postprandial distress syndrome (PDS) and epigastric pain syndrome.

SUMMARY

The pathophysiology of FD involves several mechanisms. Delayed gastric emptying is observed in approximately 30% of FD patients but does not correlate with symptom patterns or severity. Impaired gastric accommodation is important in the pathophysiology, particularly for PDS. Visceral hypersensitivity, characterized by heightened sensitivity to normal activities, contributes to the perception of discomfort or pain in FD. Alterations to the duodenal mucosa, including impaired mucosal barrier function and low-grade inflammation, are also implicated in the pathogenesis of FD. Microbial dysbiosis and psychological factors such as stress can further exacerbate symptoms. Treatment options include dietary modifications, establishing a physician-patient relationship, acid suppressants, prokinetics, neuromodulators, and behavioral therapies. Dietary recommendations include eating smaller, more frequent meals, and avoiding trigger foods. Acid suppressants are used as the first-line treatment. Prokinetics and neuromodulators aim to improve gastric motility and central pain processing, respectively. Behavioral therapies, including cognitive behavioral therapy and hypnotherapy, have shown benefits for refractory FD. Severe and refractory cases may require combination therapies or experimental treatments.

KEY MESSAGES

FD is a disorder of gut-brain interaction involving diverse pathophysiological mechanisms. Individualized treatment based on symptoms and responses to interventions is crucial. Further research is needed to improve the understanding of FD and advance the development of effective therapies.

Non-esophageal eosinophilic gastrointestinal diseases: a narrative review

Eosinophilic gastrointestinal disorders are a group of rare diseases characterized by the infiltration of eosinophils in the gastrointestinal wall in a greater amount than in homeostatic conditions. 'Non-esophageal eosinophilic gastrointestinal disorders' is the umbrella term for all eosinophilic gastrointestinal disorders outside of the well known eosinophilic esophagitis. This includes eosinophilic gastritis, eosinophilic enteritis and eosinophilic colitis. The clinical presentation is atypical and not very different for the three disorders. The depth of infiltration has a bigger influence on the presenting symptoms than the disease location. Although the frequency of diagnosis and research in this subject is increasing over time, non-esophageal eosinophilic disorders are rare and high quality evidence is limited to date. In this narrative review, we provide an overview of the latest insights in the pathophysiology, diagnostic approach and available treatment options. Transcriptome studies have found the pathogenesis to be T helper type 2 driven. Various laboratory findings can be used to trigger raised suspicion and investigation with endoscopy. As the endoscopic appearance of the mucosa is normal in most cases, multiple biopsies in each segment are needed to quantify the amount of eosinophils in the tissue. Eosinophilic cut-offs for diagnosis are a controversial topic and a consensus is still lacking. A recently developed tissue based diagnostic platform which measures differentially expressed genes might be available in the future to classify patients with intermediate eosinophilic tissue levels under the cut-off. For the treatment, corticosteroids are still the cornerstone of treatment but promising research suggests a role of biologicals, such as Lirentelimab (anti-siglec 8) in particular.

Inflammatory map of the gastroduodenal mucosa in patients with upper gastrointestinal symptoms. The role of H. pylori infection

INTRODUCTION AND AIM

The gastric mucosa has been studied since the pre-Helicobacter pylori (H. pylori) era, but the complete descriptions of the stomach and duodenum have been anecdotal, and those of the distal duodenum, exceptional. Our aim was to evaluate the different epidemiologic characteristics and the gastroduodenal inflammatory status in patients with upper gastrointestinal symptoms.

MATERIALS AND METHODS

We studied 138 patients divided into: the non-ulcer group (functional dyspepsia [n = 77] and GERD [n = 27]) and the ulcer group (peptic ulcer [n = 13] and duodenal ulcer [n = 21]). Ten biopsy samples (2 from the corpus, 3 from the antrum, 3 from the proximal duodenum, and 2 from the distal duodenum) were taken in each patient for histologic and/or microbiologic study.

RESULTS

The prevalence of dyspepsia, functional dyspepsia, and H. pylori was 80.4%, 69.4%, and 82.6%, respectively. The frequency of superficial chronic gastritis in the corpus was significantly higher in the ulcer group vs. the non-ulcer group, whereas there was more chronic atrophic gastritis in the antrum in the ulcer group (P < 0.05). Duodenitis was significantly more frequent in the ulcer group vs. the non-ulcer group, in both the proximal and distal duodenum. Pangastroduodenitis was a significant finding in the ulcer group. In both groups, chronic gastritis (corpus and antrum) and duodenitis (proximal and distal) were significantly related to the presence of H. pylori. Proximal duodenitis is not an uncommon finding in functional dyspepsia (37.7%) and is twice as frequent as distal duodenitis (16.9%).

CONCLUSIONS

The ulcer group presented with a gastroduodenal inflammatory map different from that of the non-ulcer group and was characterized by a higher frequency of superficial chronic gastritis in the corpus, chronic atrophic gastritis in the antrum, and a very high frequency of proximal duodenitis.

Review article: Functional dyspepsia-a gastric disorder, a duodenal disorder or a combination of both?

BACKGROUND

Functional dyspepsia (FD) is one of the most frequent conditions in gastroenterological outpatient health care. Most recent research in FD has shifted its focus to duodenal pathophysiological mechanisms, although current treatments still focus mainly the stomach.

AIM

The aim of the study was to provide a comprehensive overview of the pathophysiology of FD focusing on a paradigm shift from gastric towards duodenal mechanisms.

METHODS

We conducted a literature search in PubMed for studies describing mechanisms that could possibly cause FD.

RESULTS

The pathophysiology of FD remains incompletely understood. Recent studies show that duodenal factors such as acid, bile salt exposure and eosinophil and mast cell activation correlate with symptom pattern and burden and can be associated with gastric sensorimotor dysfunction. The evolving data identify the duodenum an interesting target for new therapeutic approaches. Furthermore, the current first-line treatment, that is proton pump inhibitors, reduces duodenal low-grade inflammation and FD symptoms.

CONCLUSION

Future research for the treatment of FD should focus on the inhibition of duodenal mast cell activation, eosinophilia and loss of mucosal integrity.

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.

Clinical Implications of Low-grade Duodenal Eosinophilia in Functional Dyspepsia: A Prospective Real-life Study

BACKGROUND

Functional dyspepsia (FD) is a multifactorial disorder with no targeted therapy. Duodenal eosinophilia and low-grade inflammation are potential pathogenic mechanisms. However, the impact of duodenal eosinophils (D-EO) histologic evaluation in real-life clinical practice was not explored.

AIM

To evaluate the clinical utility of D-EO and low-grade inflammation in FD in real-life practice.

MATERIALS AND METHODS

A multicenter prospective study was conducted. A total of 636 patients who meet Rome-III criteria were selected before upper endoscopy and 516 patients were included after normal endoscopy were assessed. Clinical parameters, Helicobacter pylori ( H. pylori), and duodenal histology were evaluated.

RESULTS

FD subtypes were 231 (45%) patients who had epigastric pain syndrome (EPS), 168 (33%) postprandial distress syndrome (PDS), and 117 (22%) EPS/PDS overlap. Two hundred fifty-nine (50.3%) patients were H. pylori+ . Histologic duodenal grading of chronic inflammation and intraepithelial lymphocytes showed no difference between FD subtypes. Increased in D-EO densities (>10 per high power field) was significant in PDS compared with EPS and EPS/PDS overlap subtypes. The odds ratio of PDS in subjects with duodenal eosinophilia densities was 2.28 (95% CI, 1.66-3.14; P <0.0001), adjusting for age, gender, H. pylori and nonsteroidal anti-inflammatory drug the odds ratio was 3.6 (95% CI, 2.45-5.28; P <0.0001). receiver operating characteristic curve analysis further demonstrated that low-grade duodenal eosinophilia, in particular H. pylori- , was highly accurate for PDS with the area under the curve 0.731 compared with H. pylori+ area under the curve 0.598. Furthermore, low-grade duodenal eosinophilia was significantly correlated with treatment response under 4 to 6 weeks of proton pump inhibitor therapy.

CONCLUSION

Our findings suggest that low-grade duodenal eosinophilia is associated with PDS subtype non- H. pylori FD patients and could be a useful marker of treatment response.

Understanding and managing patients with overlapping disorders of gut-brain interaction

Disorders of gut-brain interaction (DGBI) are frequently encountered in clinical practice, and recommendations for diagnosis and management are well established. In a large subset of patients, more than one DGBI diagnosis is present. This group of patients with more than one DGBI diagnosis have higher symptom severity and impact than patients with only one DGBI diagnosis, and the management approach is not well established for those with overlapping diagnoses. This Review aims to guide clinicians to understand, recognise, and manage overlapping DGBI by identifying causes and pitfalls of overlap conditions, and presenting potential practical approaches to diagnosis, treatment, and follow-up. Several clinical factors can contribute to finding overlapping DGBI, including the anatomical basis of the Rome diagnostic criteria, the potential confusion of symptom descriptors, and patients' biases towards higher symptom intensity ratings. Overlapping DGBI could also be caused by mechanistic factors such as pathophysiological mechanisms involving multiple gastrointestinal segments, and the effect of disorders in one segment on sensorimotor function in remote gastrointestinal parts, through neural or hormonal signalling. Key initial steps in the management of overlapping DGBI are detailed history taking, which can be facilitated using pictograms; carefully assessing the relative timing and cohesion of different symptoms; and recognising associated psychosocial dysfunction. Unnecessary technical investigations and complex combination treatment schedules should be avoided. Based on the identification of the dominant symptom pattern and putative underlying pathophysiological mechanisms, a single treatment modality should preferably be initiated, considering the efficacy spectrum of different therapies. Follow-up of the patient's condition allows the therapeutic approach to be adjusted as needed, while avoiding unnecessary additional technical investigations.

Targeting the altered duodenal microenvironment in functional dyspepsia

Duodenal micro-inflammation and microbial dysregulation are increasingly recognized to play an important role in functional dyspepsia (FD) pathophysiology, previously regarded as a purely functional disorder. With current therapeutic options contested through insufficient efficacy or unfavorable adverse effects profiles, novel treatments directed to duodenal alterations could result in superior symptom control in at least a subset of patients. Indeed, recent advances in FD research provided evidence for anti-inflammatory therapies to relieve gastroduodenal symptoms by reducing duodenal eosinophils or mast cells. In addition, restoring microbial homeostasis by probiotics proved to be successful in FD. As the exact mechanisms by which these novel pharmacological approaches result in clinical benefit often remain to be elucidated, future research should focus on how immune activation and dysbiosis translate into typical FD symptomatology.

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.

Low-grade duodenal eosinophilia is associated with cagA in Helicobacter pylori-related dyspepsia

BACKGROUND AND AIM

Functional dyspepsia (FD) is a multifactorial disorder. Helicobacter pylori (H. pylori)-related dyspepsia (HpD) may be considered a separate entity. Duodenal eosinophilia is a potential pathogenic mechanism in FD. However, the impact of duodenal eosinophilia and H. pylori virulence genes in HpD was not explored. We aim to evaluate the association of H. pylori virulence genes and low-grade duodenal eosinophilia in HpD.

METHODS

A multi-center cross-sectional study was conducted. A total of 301 patients who meet Rome-III criteria were selected before upper endoscopy, and 95 patients were included after normal endoscopy and positive H. pylori in gastric biopsies were assessed. Clinical parameters, H. pylori virulence genes (cagA, oipA, and vacA) and duodenal histology were evaluated.

RESULTS

Sixty-nine (72%) patients had epigastric pain syndrome (EPS), 17 (18%) post-prandial distress syndrome (PDS) and 9 (10%) EPS/PDS overlap. FD syndromes were not associated with cagA or oipA strains. A significantly trend of vacA s1/m1 (78%) and s1/m2 (80%) positive strains in EPS was observed. Histological duodenal grading of chronic inflammation, low-grade duodenal eosinophilia and intra-epithelial lymphocytes showed no difference in oipA and vacA strains. Low-grade duodenal eosinophilia was significant in cagA positive strain, and the OR for low-grade duodenal eosinophilia with H. pylori cagA positive strain was 4.2 (95% CI, 1.78-9.93). Adjusting for age, gender, smoking, diabetes, alcohol, PPI, and NSAID, the OR was 5.44 (1.989-14.902).

CONCLUSION

Our findings suggest that low-grade duodenal eosinophilia is significantly associated with cagA strain in HpD.

The Relationship between Eosinophil Density in the Colonic Mucosa and Eosinophil Blood Count in Children: A Cross-Sectional Study

Eosinophils are found in the mucosa of the healthy gastrointestinal tract, but they also often accompany gastrointestinal diseases. We hypothesized that a positive correlation exists between blood eosinophil count and colonic eosinophil mucosal density in children. Electronic health records regarding 181 colonoscopies, performed with biopsy in the years 2019-2022, were screened for information on blood and colonic eosinophil count, age, sex, diagnoses, weight, height, white blood cell (WBC) count, serum C-reactive protein (CRP), and total IgE concentration. The median age (IQR) of the 107 included children (109 colonoscopies) was 12.4 years (8.1-15.5); 32 presented with blood eosinophilia (29.3%). The median eosinophil density/high-power field in the colonic mucosa was 22.5 (9-31). We found a weak correlation between colonic mucosal eosinophil density and blood eosinophil count (r = 0.295, 95% CI 0.108-0.462, p = 0.0018). This association was more pronounced in patients with elevated CRP (r = 0.529, 95% CI 0.167-0.766, p = 0.0054) and older than 12.4 years (r = 0.448, 95% CI 0.197-0.644, p = 0.00068). Peripheral blood eosinophilia might hint at increased mucosal colonic eosinophil density, especially in older children and in the presence of systemic inflammation. However, it seems unlikely that blood and colonic eosinophilia are strongly linked in younger children. Studies in adults are warranted.

Updates in functional dyspepsia and bloating

PURPOSE OF REVIEW

Functional dyspepsia and bloating are common gastrointestinal conditions that frequently lead to gastroenterology referral. Both disorders have a significant negative impact on patients' quality of life and the healthcare system. The purpose of this review is to highlight important new findings in the cause, pathophysiology and treatment of these two disorders.

RECENT FINDINGS

Confocal laser endomicroscopy identified changes in epithelial barrier structure and function, providing important insights into the development of functional dyspepsia symptoms when combined with new observations of localized duodenal inflammation. Changes in the gut microbiome may be responsible for functional dyspepsia symptoms in some patients and may respond to gut-selective antibiotics. New data from the NIH-sponsored Gastroparesis Consortium confirmed that functional dyspepsia and gastroparesis are not distinct disorders but rather exist on a spectrum. Virtual reality may be a new therapeutic option for the treatment of functional dyspepsia. A novel questionnaire was developed and validated to assess symptoms, prevalence and impact in patients with bloating and distension. A meta-analysis identified medications to treat symptoms of bloating in patients with irritable bowel syndrome and constipation.

SUMMARY

Advances in our understanding of the pathophysiology of functional dyspepsia and bloating are leading to important changes in medical therapies.

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.

Analysis of Neurodevelopment in Children Born Extremely Preterm Treated With Acid Suppressants Before Age 2 Years

IMPORTANCE

Children born preterm are at increased risk of adverse neurodevelopmental outcomes and may be particularly vulnerable to the effects of gastric acid suppression during infancy.

OBJECTIVE

To assess whether early acid suppressant use in infants born extremely preterm is associated with poorer neurodevelopmental outcomes.

DESIGN, SETTING, AND PARTICIPANTS

The Extremely Low Gestational Age Newborn study was a multicenter, longitudinal cohort study of infants born before 28 weeks' gestational age between March 22, 2002, and August 31, 2004. The current analyses were performed from September 12, 2020, through September 22, 2022. Of the 1506 infants enrolled, 284 died before discharge and 22 died before 24 months of age. An additional 2 died before age 10 years, leaving 1198 (79.5%) eligible for a visit. Of these, 889 (74%) participated in the visit at age 10. At age 10 years, the association of early-life acid suppressant use with neurocognitive, neurodevelopmental, and psychiatric symptomatology was assessed.

EXPOSURES

Acid suppressant use before 24 months of age was determined from medical records and from questionnaires administered to mothers.

MAIN OUTCOMES AND MEASURES

Neurodevelopmental assessments at age 10 years included the School-Age Differential Ability Scales-II, the Developmental Neuropsychological Assessment-II, the Autism Diagnostic Observation Schedule-2, the Social Responsiveness Scale-2, and the Child Symptom Inventory-4 for attention-deficit/hyperactivity disorder (ADHD), depression, and anxiety.

RESULTS

Of the 889 participants assessed at age 10 years (mean [SD] age, 9.97 [0.67] years; mean [SD] gestational age at birth, 26.1 [1.3] weeks; 455 [51.2%] male), 368 (41.4%) had received acid suppressants by 24 months of age. Associations were observed between acid suppressant use and decreased full-scale IQ z score (adjusted β, -0.29; 95% CI, -0.45 to -0.12), verbal IQ z score (adjusted β, -0.34; 95% CI, -0.52 to -0.15), nonverbal IQ z score (adjusted β, -0.22; 95% CI to -0.39 to -0.05), working memory z score (adjusted β, -0.26; 95% CI to -0.45, -0.08), autism spectrum disorder (adjusted relative risk, 1.84; 95% CI, 1.15-2.95), and epilepsy (adjusted relative risk, 2.07; 95% CI, 1.31 to 3.35). Results were robust to multiple sensitivity analyses. Use of acid suppressants was not associated with inhibitory control, ADHD, anxiety, or depression.

CONCLUSIONS AND RELEVANCE

The results of this cohort study suggest that early-life use of acid suppressants in extremely preterm infants may be associated with poorer neurodevelopmental outcomes and add to evidence indicating caution in use of these agents.

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.

Effect of a Proton Pump Inhibitor on the Duodenum Microbiome of Gastric Ulcer Patients

The gut microbiota are regarded as a functional organ that plays a substantial role in human health and disease. Proton pump inhibitors (PPIs) are widely used in medicine but can induce changes in the overall gut microbiome and cause disease-associated dysbiosis. The microbiome of the duodenum has not been sufficiently studied, and the effects of PPIs on the duodenal microbiome are poorly understood. In this study, we investigated the effect of PPI administration on duodenum microbiota in patients with a gastric ulcer. A total of 12 gastric ulcer patients were included, and PPI (Ilaprazole, Noltec^®, 10 mg) was prescribed in all patients for 4 weeks. A total of 17 samples from the second portion of the duodenum were analyzed. Microbiome compositions were assessed by sequencing the V3–V4 region of the 16s rRNA gene (Miseq). Changes in microbiota compositions after 4 weeks of PPI treatment were analyzed. a-Diversity was higher after PPI treatment (p = 0.02, at Chao1 index), and β-diversity was significantly different after treatment (p = 0.007). Welch’s t-test was used to investigate changes in phyla, genus, and species level, and the abundance of Akkermansia muciniphila, belonging to the phylum Verrucomicrobia, and Porphyromonas endodontalis, belonging to the phylum Bacteroidetes, was significantly increased after treatment (p = 0.044 and 0.05). PPI administration appears to induce duodenal microbiome dysbiosis while healing gastric ulcers. Further large-scale studies on the effects of PPIs on the duodenal microbiome are required.

British Society of Gastroenterology guidelines on the management of functional dyspepsia

Functional dyspepsia (FD) is a common disorder of gut-brain interaction, affecting approximately 7% of individuals in the community, with most patients managed in primary care. The last British Society of Gastroenterology (BSG) guideline for the management of dyspepsia was published in 1996. In the interim, substantial advances have been made in understanding the complex pathophysiology of FD, and there has been a considerable amount of new evidence published concerning its diagnosis and classification, with the advent of the Rome IV criteria, and management. The primary aim of this guideline, commissioned by the BSG, is to review and summarise the current evidence to inform and guide clinical practice, by providing a practical framework for evidence-based diagnosis and treatment of patients. The approach to investigating the patient presenting with dyspepsia is discussed, and efficacy of drugs in FD summarised based on evidence derived from a comprehensive search of the medical literature, which was used to inform an update of a series of pairwise and network meta-analyses. Specific recommendations have been made according to the Grading of Recommendations Assessment, Development and Evaluation system. These provide both the strength of the recommendations and the overall quality of evidence. Finally, in this guideline, we consider novel treatments that are in development, as well as highlighting areas of unmet need and priorities for future research.

Factors associated with mood disorders and the efficacy of the targeted treatment of functional dyspepsia: A randomized clinical trial

Background

Patients with functional dyspepsia (FD) are often accompanied by mood disorders (MDs). This study aimed to identify factors associated with MDs in patients with FD and evaluate the efficacy of targeted treatment plans.

Methods

Relevant scales were used to assess MDs. Patients with FD having MDs and acid reflux were treated with flupentixol and melitracen (FM) and acid-suppressive therapy (AST) (histamine-2 receptor antagonists (H2RAs) (group A) or proton pump inhibitors (PPIs) (group B)), and those without acid reflux (group C) did not receive AST. Patients with FD without MDs were randomly administered H2RAs (group D) or PPIs (group E). The primary endpoints were factors associated with MDs and improvement in gastrointestinal (GI) symptoms and MDs in patients with FD.

Results

A total of 362 patients with FD were enrolled in this study. Patients with FD having high GI score and low education were found prone to MDs. At week 2, the remission rate of overall GI symptoms and depression was significantly higher in group B than that in groups A and C [GI: 72.72% (32/44) vs. 47.73% (21/44) and 72.72% (32/44) vs. 38.94% (44/113), all P &lt; 0.05; depression: 72.22% (26/36) vs. 41.67% (15/36) and 72.22% (26/36) vs. 41.57% (37/89), all P &lt; 0.05]. Furthermore, the remission rate of overall GI symptoms was significantly higher in group E than that in group D [60.29% (41/68) vs. 42.65% (29/68), P &lt; 0.05]. At week 8, similar efficacies and adverse reactions were observed in these groups.

Conclusion

The risk factors for MDs were high GI scores and low literacy rates. Thus, targeted treatment (FM+PPIs for patients with MDs; PPIs for patients without MDs) can improve the efficacy of patients with FD.

Clinical trial registration

www.chictr.org.cn, identifier ChiCTR2100053126.

Eosinophils, Hypoxia-Inducible Factors, and Barrier Dysfunction in Functional Dyspepsia

Functional dyspepsia (FD) is a highly prevalent disorder of gut-brain interaction (DGBI), previously known as a functional gastrointestinal disorder. Characterized by early satiety, postprandial fullness, and/or epigastric pain or burning, diagnosis depends on positive symptomatology and exclusion of obvious structural diseases. A subtle inflammatory phenotype has been identified in FD patients, involving an increase in duodenal mucosal eosinophils, and imbalances in the duodenal gut microbiota. A dysregulated epithelial barrier has also been well described in FD and is thought to be a contributing factor to the low-grade duodenal inflammation observed, however the mechanisms underpinning this are poorly understood. One possible explanation is that alterations in the microbiota and increased immune cells can result in the activation of cellular stress response pathways to perpetuate epithelial barrier dysregulation. One such cellular response pathway involves the stabilization of hypoxia-inducible factors (HIF). HIF, a transcriptional protein involved in the cellular recognition and adaptation to hypoxia, has been identified as a critical component of various pathologies, from cancer to inflammatory bowel disease (IBD). While the contribution of HIF to subtle inflammation, such as that seen in FD, is unknown, HIF has been shown to have roles in regulating the inflammatory response, particularly the recruitment of eosinophils, as well as maintaining epithelial barrier structure and function. As such, we aim to review our present understanding of the involvement of eosinophils, barrier dysfunction, and the changes to the gut microbiota including the potential pathways and mechanisms of HIF in FD. A combination of PubMed searches using the Mesh terms functional dyspepsia, functional gastrointestinal disorders, disorders of gut-brain interaction, duodenal eosinophilia, barrier dysfunction, gut microbiota, gut dysbiosis, low-grade duodenal inflammation, hypoxia-inducible factors (or HIF), and/or intestinal inflammation were undertaken in the writing of this narrative review to ensure relevant literature was included. Given the findings from various sources of literature, we propose a novel hypothesis involving a potential role for HIF in the pathophysiological mechanisms underlying FD.

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.

Epithelial protective therapy in comorbid diseases. Practical Guidelines for Physicians

In 2021 the first multidisciplinary National Consensus on the pathophysiological and clinical aspects of Increased Epithelial Permeability Syndrome was published. The proposed guidelines are developed on the basis of this Consensus, by the same team of experts. Twenty-eight Practical Guidelines for Physicians statements were adopted by the Expert Council using the "delphic" method. Such main groups of epithelial protective drugs as proton pump inhibitors, bismuth drugs and probiotics are discussed in these Guidelines from the positions of evidence-based medicine. The clinical and pharmacological characteristics of such a universal epithelial protector as rebamipide, acting at the preepithelial, epithelial and subepithelial levels, throughout gastrointestinal tract, are presented in detail.

The Role of Leaky Gut in Functional Dyspepsia

Patients with functional dyspepsia (FD) complain of epigastric symptoms with no identifiable cause. Increased intestinal permeability has been described in these patients, especially in the proximal small bowel or duodenum, and was associated with mucosal immune activation and symptoms. In this review, we discuss duodenal barrier function, including techniques currently applied in FD research. We summarize the available data on duodenal permeability in FD and factors associated to increased permeability, including mucosal eosinophils, mast cells, luminal and systemic factors. While the increased influx of antigens into the duodenal mucosa could result in local immune activation, clinical evidence for a causal role of permeability is lacking in the absence of specific barrier-protective treatments. As both existing and novel treatments, including proton pump inhibitors (PPI) and pre- or probiotics may impact duodenal barrier function, it is important to recognize and study these alterations to improve the knowledge and management of FD.

[Duodenal Microbiome and Its Clinical Implications in Functional Dyspepsia]

Functional dyspepsia is one of the most common functional gastrointestinal disorders with chronic bothersome epigastric pain or postprandial fullness without a definite organic cause. Despite its high clinical burden, the treatment modalities for modulating impaired motor dysfunction and visceral hypersensitivity have been unsatisfactory. Recently, studies demonstrating low-grade inflammation and dysbiosis of the duodenal mucosa as potential triggers of the disease have attracted attention. Observations, such as an increase in the proportion of oral commensal bacteria in the duodenal mucosa, such as Streptococcus species, highlight the importance of bacterial ecology in developing symptoms of functional dyspepsia. In the near future, anti-inflammatory drugs and probiotics that modulate the host-microbiome interaction are expected to emerge to treat functional dyspepsia.

Impressions and aspirations from the FDA GREAT VI Workshop on Eosinophilic Gastrointestinal Disorders Beyond Eosinophilic Esophagitis and Perspectives for Progress in the Field

The US Food and Drug Administration hosted a workshop on July 21, 2021, to discuss the disease characteristics, natural history, and end points to assess treatment benefit in patients with eosinophilic gastrointestinal disorders (EGIDs) beyond eosinophilic esophagitis (EoE). Notably, EGIDs beyond EoE, such as eosinophilic gastritis, eosinophilic enteritis, and eosinophilic colitis, herein referred to as non-EoE EGIDs, are understudied relative to EoE. This workshop provided a forum for open discussion among stakeholders-medical professionals (including their societies and research groups), Food and Drug Administration representatives, an industry representative, and a patient representative-to facilitate drug development. Experts in many disciplines related to EGIDs, including allergy, immunology, epidemiology, gastroenterology, and pathology, and both adult and pediatric clinicians contributed. Herein, we discuss some of the insights of the material presented at the meeting and present perspectives on moving the field forward toward drug approval.

Current Treatment Options and Therapeutic Insights for Gastrointestinal Dysmotility and Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGIDs) have been re-named as disorders of gut-brain interactions. These conditions are not only common in clinical practice, but also in the community. In reference to the Rome IV criteria, the most common FGIDs, include functional dyspepsia (FD) and irritable bowel syndrome (IBS). Additionally, there is substantial overlap of these disorders and other specific gastrointestinal motility disorders, such as gastroparesis. These disorders are heterogeneous and are intertwined with several proposed pathophysiological mechanisms, such as altered gut motility, intestinal barrier dysfunction, gut immune dysfunction, visceral hypersensitivity, altered GI secretion, presence and degree of bile acid malabsorption, microbial dysbiosis, and alterations to the gut-brain axis. The treatment options currently available include lifestyle modifications, dietary and gut microbiota manipulation interventions including fecal microbiota transplantation, prokinetics, antispasmodics, laxatives, and centrally and peripherally acting neuromodulators. However, treatment that targets the pathophysiological mechanisms underlying the symptoms are scanty. Pharmacological agents that are developed based on the cellular and molecular mechanisms underlying pathologies of these disorders might provide the best avenue for future pharmaceutical development. The currently available therapies lack long-term effectiveness and safety for their use to treat motility disorders and FGIDs. Furthermore, the fundamental challenges in treating these disorders should be defined; for instance, 1. Cause and effect cannot be disentangled between symptoms and pathophysiological mechanisms due to current therapies that entail the off-label use of medications to treat symptoms. 2. Despite the knowledge that the microbiota in our gut plays an essential part in maintaining gut health, their exact functions in gut homeostasis are still unclear. What constitutes a healthy microbiome and further, the precise definition of gut microbial dysbiosis is lacking. More comprehensive, large-scale, and longitudinal studies utilizing multi-omics data are needed to dissect the exact contribution of gut microbial alterations in disease pathogenesis. Accordingly, we review the current treatment options, clinical insight on pathophysiology, therapeutic modalities, current challenges, and therapeutic clues for the clinical care and management of functional dyspepsia, gastroparesis, irritable bowel syndrome, functional constipation, and functional diarrhea.

Duodenal Dysbiosis and Relation to the Efficacy of Proton Pump Inhibitors in Functional Dyspepsia

Proton pump inhibitors (PPI) may improve symptoms in functional dyspepsia (FD) through duodenal eosinophil-reducing effects. However, the contribution of the microbiome to FD symptoms and its interaction with PPI remains elusive. Aseptic duodenal brushings and biopsies were performed before and after PPI intake (4 weeks Pantoprazole 40 mg daily, FD-starters and controls) or withdrawal (2 months, FD-stoppers) for 16S-rRNA sequencing. Between- and within-group changes in genera or diversity and associations with symptoms or duodenal factors were analyzed. In total, 30 controls, 28 FD-starters and 19 FD-stoppers were followed. Mucus-associated Porphyromonas was lower in FD-starters vs. controls and correlated with symptoms in FD and duodenal eosinophils in both groups, while Streptococcus correlated with eosinophils in controls. Although clinical and eosinophil-reducing effects of PPI therapy were unrelated to microbiota changes in FD-starters, increased Streptococcus was associated with duodenal PPI effects in controls and remained higher despite withdrawal of long-term PPI therapy in FD-stoppers. Thus, duodenal microbiome analysis demonstrated differential mucus-associated genera, with a potential role of Porphyromonas in FD pathophysiology. While beneficial effects of short-term PPI therapy were not associated with microbial changes in FD-starters, increased Streptococcus and its association with PPIeffects in controls suggest a role for duodenal dysbiosis after long-term PPI therapy.

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.

Moxibustion Regulates Gastrointestinal Motility via HCN1 in Functional Dyspepsia Rats

Background

Moxibustion therapy has been found to ameliorate clinical symptoms of functional dyspepsia (FD). We aimed to examine the regulatory effect of moxibustion on the gastrointestinal (GI) motility in FD and explore the underlying mechanism based on the hyperpolarization-activated cyclic nucleotide-gated cation channel 1 (HCN1).

Material/Methods

Moxibustion therapy was used in FD rats induced by using classic tail-pinch and irregular feeding. Weight gain and food intake were recorded weekly, followed by detecting gastric residual rate (GRR) and small intestine propulsion rate (IPR). Next, western blotting was performed to determine the expression levels of HCN1 in the gastric antrum. qRT-PCR was used to detect HCN1 in the small intestine and hypothalamic satiety center. Double immunolabeling was used for HCN1 and ICCs in gastric antrum and small intestine.

Results

The obtained results suggested that moxibustion treatment could increase weight gain and food intake in FD rats. The GRR and IPR were compared among the groups, which showed that moxibustion treatment could decrease GRR and increase IPR. Moxibustion increased the expression of HCN1 in the gastric antrum, small intestine, and hypothalamic satiety center. Histologically, the co-expressions of HCN1 and ICCs tended to increase in gastric antrum and small intestine. Meanwhile, HCN channel inhibitor ZD7288 prevented the above-mentioned therapeutic effects of moxibustion.

Conclusions

The results of the present study suggest that moxibustion can effectively improve the GI motility of FD rats, which may be related to the upregulation of HCN1 expression in gastric antrum, small intestine, and satiety center.

Duodenum at a crossroads: Key integrator of overlapping and psychological symptoms in functional dyspepsia?

The study of the interaction between gastrointestinal (GI) function and psychological features is a complex and developing field. The bidirectional communication between the gut and the brain or gut-brain axis is considered as a pivotal player in the pathogenesis of the highly prevalent functional GI disorders, including irritable bowel syndrome and functional dyspepsia (FD), which have been redefined as disorders of gut-brain interaction. However, the mechanisms through which changes in the gut alter brain functioning, feelings, and behavior remain unclear. Based on the presence of duodenal pathology in adult FD patients, Ronkainen et al. provide the first prospective evidence for duodenal eosinophils potentially driving anxiety. Also in this edition, associations between gastroduodenal pathology and rumination syndrome, which may coexist with FD, have now been confirmed in children by Friesen et al. Together these findings confirm not only the potential role of duodenal alterations in determining overlapping upper GI but also psychological symptoms, which result from bidirectional and complex interactions. In this review, we provide an overview of the recent advances in this field and highlight the novel contributions of the original studies of Ronkainen et al. and Friesen et al. to this topic.

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.

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.

Functional dyspepsia: A critical appraisal of the European consensus from a global perspective

The European Society for Neurogastroenterology and Motility's (ESNM) consensus document on functional dyspepsia (FD) has provided a critical review of the evidence for 36 statements highly relevant to the diagnosis and treatment of FD. We provide here our expert opinion on the North American, Australian and Asian assessments of the same topics discussed, and provide evidence where the ESNM consensus may deviate from those in the other continents. New and exciting data about the pathogenesis of FD are emerging including the possible central role of duodenal micro-inflammation (most notably eosinophilic duodenitis and intestinal mast cell disease), but this is a very dynamic field with several gaps remaining in our understanding that are summarized in this review. Identification of non-invasive biomarkers and testing of targeted therapies, including assessing the benefits of multidisciplinary teams in the management of FD, should be future priorities.

Efficacy and safety of spore-forming probiotics in the treatment of functional dyspepsia: a pilot randomised, double-blind, placebo-controlled trial

BACKGROUND

Current treatments for functional dyspepsia have limited efficacy or present safety issues. We aimed to assess spore-forming probiotics in functional dyspepsia as monotherapy or add-on therapy to long-term treatment with proton-pump inhibitors.

METHODS

In this single-centre, randomised, double-blind, placebo-controlled pilot trial that took place at University Hospitals Leuven (Leuven, Belgium), adult patients (≥18 years) with functional dyspepsia (as defined by Rome IV criteria, on proton-pump inhibitors or off proton-pump inhibitors) were randomly assigned (1:1) via computer-generated blocked lists, stratified by proton-pump inhibitor status, to receive 8 weeks of treatment with probiotics (Bacillus coagulans MY01 and Bacillus subtilis MY02, 2·5 × 10⁹ colony-forming units per capsule) or placebo consumed twice per day, followed by an open-label extension phase of 8 weeks. Individuals with a history of abdominal surgery, diabetes, coeliac or inflammatory bowel disease, active psychiatric conditions, and use of immunosuppressant drugs, antibiotics, or probiotics in the past 3 months were excluded. All patients and on-site study personnel were masked to treatment allocation in the first 8 weeks. Symptoms, immune activation, and faecal microbiota were assessed and recorded. The primary endpoint was a decrease of at least 0·7 in the postprandial distress syndrome (PDS) score of the Leuven Postprandial Distress Scale in patients with a baseline PDS score of 1 or greater (at least mild symptoms), assessed in the intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT04030780.

FINDINGS

Between June 3, 2019, and March 11, 2020, of 93 individuals assessed for eligibility, we included 68 patients with functional dyspepsia (51 [75%] women, mean age 40·1 years [SD 14·4], 34 [50%] on proton-pump inhibitors). We randomly assigned 32 participants to probiotics and 36 to placebo. The proportion of clinical responders was higher with probiotics (12 [48%] of 25) than placebo (six [20%] of 30; relative risk 1·95 [95% CI 1·07-4·11]; p=0·028). The number of patients with adverse events was similar with probiotics (five [16%] of 32) and placebo (12 [33%] of 36). Two serious adverse events occurring during the open-label phase (appendicitis and syncope in two separate patients) were assessed as unlikely to be related to the study product.

INTERPRETATION

In this exploratory study, B coagulans MY01 and B subtilis MY02 were efficacious and safe in the treatment of functional dyspepsia. Participants had potentially beneficial immune and microbial changes, which could provide insights into possible underlying mechanisms as future predictors or treatment targets.

FUNDING

MY HEALTH.

Elevated F-EDN correlates with mucosal eosinophil degranulation in patients with IBS-A possible association with microbiota?

Eosinophils have been linked to functional dyspepsia; however, less is known about their role in irritable bowel syndrome (IBS). This study tested the hypothesis of alterations in levels of fecal eosinophil-derived neurotoxin (F-EDN) and eosinophil density and degranulation within the colonic mucosa of IBS patients compared with healthy controls (HC). Colonic biopsies were collected from 37 IBS patients and 20 HC and analyzed for eosinophil numbers and local degranulation of eosinophil cationic protein (ECP) by histologic procedures. Fecal samples were collected for F-EDN and microbiota analysis. Differentiated 15HL-60 cells were used in vitro to investigate the direct effect of live bacteria on eosinophil activation measured by a colorimetric assay with o-phenylenediamine (OPD) substrate. We observed a higher number of eosinophils and increased extracellular ECP in the mucosa of IBS patients compared with HC. Moreover, F-EDN levels in IBS samples were elevated compared with HC and positively correlated to extracellular ECP. Metagenomic analysis showed significant correlations between bacterial composition and eosinophil measurements in both HC and IBS patients. In vitro experiments revealed an increased degranulation of 15HL-60 after stimulation with Salmonella typhimurium, Salmonella enterica, and Yersinia enterocolitica. To conclude, we could demonstrate alterations related to eosinophils in IBS, and, for the first time, a positive correlation between F-EDN levels and degranulated eosinophils in the colonic mucosa of IBS patients. Together our results suggest that eosinophils play a role in the pathophysiology of IBS and the mechanisms might be linked to an altered microbiota.

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.

Mechanisms of Food-Induced Symptom Induction and Dietary Management in Functional Dyspepsia

Functional dyspepsia (FD) is a common disorder of gut-brain interaction, characterised by upper gastrointestinal symptom profiles that differentiate FD from the irritable bowel syndrome (IBS), although the two conditions often co-exist. Despite food and eating being implicated in FD symptom induction, evidence-based guidance for dietetic management of FD is limited. The aim of this narrative review is to collate the possible mechanisms for eating-induced and food-related symptoms of FD for stratification of dietetic management. Specific carbohydrates, proteins and fats, or foods high in these macronutrients have all been reported as influencing FD symptom induction, with removal of 'trigger' foods or nutrients shown to alleviate symptoms. Food additives and natural food chemicals have also been implicated, but there is a lack of convincing evidence. Emerging evidence suggests the gastrointestinal microbiota is the primary interface between food and symptom induction in FD, and is therefore a research direction that warrants substantial attention. Objective markers of FD, along with more sensitive and specific dietary assessment tools will contribute to progressing towards evidence-based dietetic management of FD.