Degranulated Eosinophils Contain More Fine Nerve Fibers in the Duodenal Mucosa of Patients With Functional Dyspepsia

The Association between Functional Dyspepsia and Metabolic Syndrome-The State of the Art

Functional dyspepsia is a common functional disorder of the gastrointestinal tract that is responsible for many primary care visits. No organic changes have been found to explain its symptoms. We hypothesize that modern lifestyles and environmental factors, especially psychological stress, play a crucial role in the high prevalence of functional dyspepsia and metabolic syndrome. While gastrointestinal tract diseases are rarely linked to metabolic disorders, chronic stress, obesity-related metabolic syndrome, chronic inflammation, intestinal dysbiosis, and functional dyspepsia have significant pathophysiological associations. Functional dyspepsia, often associated with anxiety and chronic psychological stress, can activate the neuroendocrine stress axis and immune system, leading to unhealthy habits that contribute to obesity. Additionally, intestinal dysbiosis, which is commonly present in functional dyspepsia, can exacerbate systemic inflammation and obesity, further promoting metabolic syndrome-related disorders. It is worth noting that the reverse is also true: obesity-related metabolic syndrome can worsen functional dyspepsia and its associated symptoms by triggering systemic inflammation and intestinal dysbiosis, as well as negative emotions (depression) through the brain-gut axis. To understand the pathophysiology and deliver an effective treatment strategy for these two difficult-to-cure disorders, which are challenging for both caregivers and patients, a psychosocial paradigm is essential.

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.

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.

Identification and genetic analysis of major gene ST3GAL4 related to serum alkaline phosphatase in chicken

Alkaline phosphatase (ALP) is a marker of osteoblast maturation and an important indicator of bone metabolism. The activity of ALP can reflect the bone metabolism and growth traits of animals, so the polymorphism affecting ALP expression deserves further study. In this study, we identified an SNP site in ST3GAL4 found by genome-wide association studies (GWAS) in previous studies, 8 SNPs were also identified by DNA sequencing. Interestingly, there were 4 SNPs (rs475471G > A, rs475533C > T, rs475621A > G, rs475647C > A) completely linked by haplotype analysis. Therefore, we selected a tag SNP rs475471G > A to further analyze the ALP level of different genotypes in Hubbard leg disease population and an F₂ chicken resource population produced by Anka and Gushi chickens and carried out population genetic analysis in 18 chicken breeds. Association analysis showed that this QTL within ST3GAL4 was highly correlated with ALP level. The mutant individuals with genotype AA had the highest ALP level, followed by GA and GG carriers. The mutant individual carriers of AA and GA genotype had higher values for body weight (BW), chest width (CW), body slanting length (BSL), pelvis width (PW) at 4-week, the semi-evisceration weight (SEW), evisceration weight (EW) and Leg weight (LW) than GG genotypes. The amplification and typing of 4852 DNA samples from 18 different breeds showed GG genotype mainly existed in egg-type chickens and dual-type chickens, while the AA genotype was mainly distributed in commercial broilers and F₂ resource population. The individual carriers of the AA genotype had the highest ALP and showed better growth performance. Besides, tissue expression analysis used Cobb broiler showed significant differences between different genotypes in the spleen and duodenum. Taken together, this was the first time to determine 9 SNPs within ST3GAL4 related to ALP in chickens, 4 of them were complete linkage with each other, which provides useful information on the mutation of ST3GAL4 and could predict the serum ALP level of chicken early and as an effective potential molecular breeding marker for chickens.

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.

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.

Eosinophil and Mast Cell Counts in the Stomach and Duodenum of Patients with Functional Dyspepsia without a Helicobacter pylori infection

BACKGROUND/AIMS

Symptom-based subtyping of functional dyspepsia (FD) is used to segregate patients into groups with homogenous pathophysiological mechanisms. This study examined whether subtyping could reflect the duodenal and gastric microinflammation in FD patients.

METHODS

Twenty-one FD patients without Helicobacter pylori infection were recruited. An endoscopic biopsy was performed in the duodenum 2nd portion, stomach antrum, and body. The eosinophil and mast cell counts per high-power field (×40) were investigated by H&E and c-kit staining, respectively. The degree of inflammatory cell infiltration, atrophy, and intestinal metaplasia was also determined by H&E staining in the stomach. The baseline characteristics and eosinophil and mast cell infiltrations were compared among the three groups (epigastric pain syndrome, postprandial distress syndrome, and overlap).

RESULTS

According to the symptom assessment, seven subjects were classified into the epigastric pain syndrome group, 10 into the postprandial syndrome group, and four into the overlap group. The baseline variables were similar in the three groups. Eosinophil infiltration was more prominent in the duodenum than in the stomach. In contrast, mast cell infiltration was similar in the duodenum and stomach. The eosinophil counts in the duodenum were similar in the three groups. The eosinophil counts in the stomach and mast cell counts in the duodenum and stomach were also similar in the three groups.

CONCLUSIONS

Duodenal eosinophil infiltration was prominent in FD patients, but the eosinophil counts were similar regardless of the symptom-based subtypes of FD. Hence, the current symptom-based subtyping of FD does not reflect duodenal eosinophil and mast cell infiltration.

Eosinophils in the Gastrointestinal Tract: Key Contributors to Neuro-Immune Crosstalk and Potential Implications in Disorders of Brain-Gut Interaction

Eosinophils are innate immune granulocytes actively involved in defensive responses and in local and systemic inflammatory processes. Beyond these effector roles, eosinophils are fundamental to maintaining homeostasis in the tissues they reside. Gastrointestinal eosinophils modulate barrier function and mucosal immunity and promote tissue development through their direct communication with almost every cellular component. This is possible thanks to the variety of receptors they express and the bioactive molecules they store and release, including cytotoxic proteins, cytokines, growth factors, and neuropeptides and neurotrophines. A growing body of evidence points to the eosinophil as a key neuro-immune player in the regulation of gastrointestinal function, with potential implications in pathophysiological processes. Eosinophil–neuron interactions are facilitated by chemotaxis and adhesion molecules, and the mediators released may have excitatory or inhibitory effects on each cell type, with physiological consequences dependent on the type of innervation involved. Of special interest are the disorders of the brain–gut interaction (DBGIs), mainly functional dyspepsia (FD) and irritable bowel syndrome (IBS), in which mucosal eosinophilia and eosinophil activation have been identified. In this review, we summarize the main roles of gastrointestinal eosinophils in supporting gut homeostasis and the evidence available on eosinophil–neuron interactions to bring new insights that support the fundamental role of this neuro-immune crosstalk in maintaining gut health and contributing to the pathophysiology of DBGIs.

Yokukansan Suppresses Gastric Hypersensitivity and Eosinophil-associated Microinflammation in Rats With Functional Dyspepsia

Background/Aims

Herbal medicine is an important complementary therapy for functional dyspepsia (FD). However, its effect against gastric hypersensitivity in patients with FD has rarely been evaluated. Yokukansan (YKS), a traditional Japanese herbal medicine, is effective against neuropathic and inflammatory pain. This study aims to use a maternal separation (MS) stress-induced FD model to investigate the effects of YKS against gastric hypersensitivity, gastric motility, and duodenal micro-inflammation.

Methods

The MS stress model was established by separating newborn Sprague-Dawley rats from their mothers for 2 hours a day from postnatal days 1 to 10. At the age of 7-8 weeks, the rats were treated with YKS at a dose of 5 mL/kg (1 g/kg) for 7 consecutive days. After YKS treatment, electromyographic activity in the acromiotrapezius muscle by gastric distention and the gastric-emptying rate were assessed. Immunohistochemical analysis of eosinophils in the duodenum and phosphorylated extracellular signal-regulated kinase (p-ERK) 1/2 in the spinal cord was performed.

Results

YKS treatment suppressed MS stress-induced gastric hypersensitivity and decreased the elevated levels of p-ERK1/2 in the spinal cord. In the gastroduodenal tract, YKS inhibited eosinophil-associated micro-inflammation but did not improve gastric dysmotility.

Conclusions

YKS treatment improved gastric hypersensitivity by alleviating eosinophil-associated micro-inflammation in the gastroduodenal tract. This treatment may be considered an effective therapeutic option for epigastric pain and micro-inflammation in patients with 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.

A Quantitative Assessment of Mucosal Eosinophils in the Gastrointestinal Tract of Children Without Detectable Organic Disease

BACKGROUND

Accurate measurements of mucosal eosinophil concentrations in gastrointestinal tracts of healthy children are necessary to differentiate health and disease states in general, and better define eosinophilic gastrointestinal diseases.

STUDY

We retrospectively reviewed gastrointestinal biopsies from children with macroscopically normal endoscopies, who, after a minimal follow-up of one year, were not diagnosed with any organic disease. Peak eosinophil concentrations and distributions were assessed from each segment of the gastrointestinal tract.

RESULTS

Three centers (Italy, United Kingdom, and Israel) contributed 202 patients (median age 13 years IQR 9.5-15.5, range 1-18 years). Median (IQR, range) eosinophil concentrations (eos/mm²) were: esophagus 0 (0-0, 0-84), stomach 0 (0-4, 0-84), duodenal bulb 20 (13-30, 7-67), second part of duodenum 20 (13-29, 0-105), terminal ileum 29 (14-51, 0-247), cecum 53 (37-89, 10-232), ascending colon 55 (25-84, 0-236), transverse colon 38 (21-67, 4-181), descending colon 29 (17-59, 0-114), sigmoid colon 25 (13-40, 0-215) and rectum 13 (4-28, 0-152). Significant geographical variance was present, however, no differences in eosinophil concentrations were identified between children with resolving symptoms vs. those with functional diagnoses, nor across age groups.

CONCLUSIONS

Standardized eosinophil concentrations from the gastrointestinal tracts of children without organic disease will serve to better define both health and disease states. No differences were found between resolved symptoms vs. functional diagnoses nor between age groups in this pediatric cohort.

Functional dyspepsia: a multifaceted problem in gastroenterology

The article presents the views on dyspepsia in world practice, data on the difficulties of diagnosis and the problem of the effectiveness of various therapy regimens. Particular attention is paid to the use of fixed forms of drugs for functional dyspepsia, in particular Omez DSR.

Functional Dyspepsia and Duodenal Eosinophil Count and Degranulation: A Multiethnic US Veteran Cohort Study

BACKGROUND

Duodenal eosinophilia may play a role in functional dyspepsia (FD), but existing study results are conflicted. We investigated the association between duodenal eosinophils (count and degranulation) and FD symptoms, accounting for atopic conditions, medications, and seasonal variations.

METHODS

In a cross-sectional study conducted in the Michael E. DeBakey VA Medical Center in Houston, Texas, we analyzed duodenal histopathology of 436 patient samples from a prospective cohort with a validated symptom survey data and chart reviews. FD was defined using Rome II symptom criteria. Eosinophil count was number per 5 high-power fields (HPF), and eosinophil degranulation was eosinophilic granules in the stroma both determined by two independent investigators.

RESULTS

The study cohort was predominantly male (87.4%) with a mean age of 59.3 (standard deviation (SD) ± 9.8). Mean and median eosinophil counts were 75.5 (± 47.8) and 63 (IQR: 43, 101) per five HPF, respectively. Duodenal eosinophilia (defined as ≥ 63 per 5 HPF) and eosinophil degranulation were present in 50.5% and 23.1% of patient samples, respectively. FD was observed in 178 patients (41.7%), but neither the mean eosinophil count nor duodenal eosinophilia was associated with FD. Eosinophil degranulation was independently associated with FD overall (OR 1.74; 95% CI 1.08, 2.78; p = 0.02) and early satiety (OR 2.04; 95% CI 1.26, 3.30; p = 0.004).

CONCLUSIONS

In this large, ethnically diverse cohort of adult patients, we found no significant association between duodenal eosinophilia and FD. However, the presence of duodenal eosinophilic degranulation, an activated eosinophil marker, was significantly associated with FD, especially early satiety.

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

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

Inflammation and Overlap of Irritable Bowel Syndrome and Functional Dyspepsia

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

Eosinophil-associated microinflammation in the gastroduodenal tract contributes to gastric hypersensitivity in a rat model of early-life adversity

Gastric hypersensitivity is a major pathophysiological feature of functional dyspepsia (FD). Recent clinical studies have shown that a large number of patients with FD present with gastroduodenal microinflammation, which may be involved in the pathophysiology of FD. However, no animal model reflecting this clinical characteristic has been established. The underlying mechanism between microinflammation and FD remains unknown. In this study, using a maternal separation (MS)-induced FD model, we aimed to reproduce the gastroduodenal microinflammation and reveal the interaction between gastroduodenal microinflammation and gastric hypersensitivity. The MS model was established by separating newborn Sprague-Dawley rats for 2 h a day from postnatal day 1 to day 10. At 7-8 wk of age, electromyography was used to determine the visceromotor response to gastric distention (GD) and immunohistochemistry was performed to detect distension-associated neuronal activation as well as immunohistological changes. Our results demonstrated that MS-induced FD rats underwent gastric hypersensitivity with GD at 60 and 80 mmHg, which are related to increased p-ERK1/2 expression in the dorsal horn of T9-T10 spinal cords. Eosinophils, but not mast cells, were significantly increased in the gastroduodenal tract, and the coexpression rate of CD11b and major basic protein significantly increased in MS rats. Treatment with dexamethasone reversed gastric hypersensitivity in MS-induced FD rats by inhibiting eosinophil infiltration. These findings indicated that neonatal MS stress induces eosinophil-associated gastroduodenal microinflammation and gastric hypersensitivity in adulthood in rats. Microinflammation contributes to gastric hypersensitivity; therefore, anti-inflammatory therapy may be effective in treating patients with FD with gastroduodenal microinflammation.NEW & NOTEWORTHY We showed for the first time that neonatal MS stress-induced FD rats undergo gastroduodenal eosinophil-associated microinflammation in adulthood. Suppression of microinflammation attenuated gastric hypersensitivity in MS rats. These findings established a functional link between microinflammation and gastric hypersensitivity, which may provide a potential clue for the clinical treatment of FD.

Ileocolonic Histopathological and Microbial Alterations in the Irritable Bowel Syndrome: A Nested Community Case-Control Study

INTRODUCTION

Histopathological alterations in the ileum and colon in irritable bowel syndrome (IBS) are controversial, and normal values are poorly established. We hypothesized that changes in mucosal immune cells characterize IBS and key changes in immune composition are associated with the mucosa-associated microbiota (MaM).

METHODS

A nested case-control study (48 IBS and 106 controls included) from 745 colonoscopy participants in a random population sample. Intraepithelial lymphocytes (IELs)/100 enterocytes and eosinophils/5 nonoverlapping high-power fields counted; mast cells identified by immunocytochemistry (CD117)/5 high-power fields. Paneth cells quantified per 5 crypts. 16S rRNA gene amplicon sequencing performed on available sigmoid MaM, n = 55 and fecal microbiota, n = 20. Microbiota profiles compared between samples with high and low IEL counts.

RESULTS

IBS had increased IELs in the terminal ileum (relative risk ratio = 1.70, 95% confidence interval 1.08-2.76, P = 0.022 adjusted for age, sex, and smoking). Cecal IELs were increased in IBS-diarrhea (relative risk ratio = 2.03, 95% confidence interval 1.13-3.63, P = 0.017). No difference was observed in alpha diversity of MaM or fecal microbiota based on IEL count. There was no difference in beta diversity of the MaM according to IEL count in the terminal ileal (TI) (P = 0.079). High TI IEL counts associated with a significant expansion of the genus Blautia (P = 0.024) and unclassified Clostridiales (P = 0.036) in colon MaM.

DISCUSSION

A modest but significant increase in IELs was observed in IBS vs. controls in a population-based setting. Subtle TI and cecal inflammation may play a pathogenic role in IBS but needs confirmation. Modest but discernible differences in the colonic MaM were seen according to TI IEL count but not IBS status.

Functional Dyspepsia and Food: Immune Overlap with Food Sensitivity Disorders

PURPOSE OF REVIEW

Functional dyspepsia (FD) is a chronic functional gastrointestinal disorder characterised by upper gastrointestinal symptoms. Here, we aimed to examine the evidence for immune responses to food in FD and overlap with food hypersensitivity conditions.

RECENT FINDINGS

A feature of FD in a subset of patients is an increase in mucosal eosinophils, mast cells, intraepithelial cytotoxic T cells and systemic gut-homing T cells in the duodenum, suggesting that immune dysfunction is characteristic of this disease. Rates of self-reported non-celiac wheat/gluten sensitivity (NCW/GS) are higher in FD patients. FD patients commonly report worsening symptoms following consumption of wheat, fermentable oligosaccharides, disaccharides, monosaccharides, or polyols (FODMAPs), high-fat foods and spicy foods containing capsaicin. Particularly, wheat proteins and fructan in wheat may drive symptoms. Immune mechanisms that drive responses to food in FD are still poorly characterised but share key effector cells to common food hypersensitivities including non-IgE-mediated food allergy and eosinophilic oesophagitis.

Management of functional dyspepsia in 2020: a clinical point of view

Dyspepsia is a disorder that refers mainly to central upper abdominal pain or discomfort. When a cause of this symptom is not identified the condition is termed functional dyspepsia (FD), that affects a large part of the general population. The relevance of FD is due to its high prevalence, but also to its chronic or intermittent course. This induces a significant burden for each national healthcare system. The pathogenesis of FD is complex and multifactorial, depending on cultural, environmental, and biological factors. Although considered of main importance in the pathophysiology of several gastroduodenal diseases, in the context of FD Helicobacter pylori (H. pylori) infection plays a limited role. The diagnosis of FD requires the exclusion of organic gastroduodenal diseases as well as H. pylori infection. Thus, the diagnostic workup includes a complete anamnesis, biochemical tests, and endoscopy with biopsy (when requested), and the satisfaction of clinic criteria recommended by the Rome IV consensus. The treatment of FD is also challenging, in fact more and more studies focused on a wide range of different therapies, with a multitude of results. The aim of this literature review is to provide an update of the new evidences useful for diagnosis and management of FD.