Evidence for Local and Systemic Immune Activation in Functional Dyspepsia and the Irritable Bowel Syndrome: A Systematic Review

Familial coaggregation and shared familiality of functional and internalizing disorders in the Lifelines cohort

BACKGROUND

Functional disorders (FDs) are characterized by persistent somatic symptoms and are highly comorbid with internalizing disorders (IDs). To provide much-needed insight into FD etiology, we evaluated FD and ID familial coaggregation and shared familiality.

METHODS

Lifelines is a three-generation cohort study, which assessed three FDs (myalgic encephalomyelitis/chronic fatigue syndrome [ME/CFS], irritable bowel syndrome [IBS], and fibromyalgia [FM]) and six IDs (major depressive disorder [MDD], dysthymia [DYS], generalized anxiety disorder [GAD], agoraphobia [AGPH], social phobia [SPH], and panic disorder [PD]) according to diagnostic criteria. Based on 153,803 individuals, including 90,397 with a first-degree relative in Lifelines, we calculated recurrence risk ratios (λRs) and tetrachoric correlations to evaluate familial aggregation and coaggregation of these disorders in first-degree relatives. We then estimated their familiality and familial correlations.

RESULTS

Familial aggregation was observed across disorders, with λR ranging from 1.45 to 2.23 within disorders and from 1.17 to 1.94 across disorders. Familiality estimates ranged from 22% (95% confidence interval [CI]: 16-29) for IBS to 42% (95% CI: 33-50) for ME/CFS. Familial correlations ranged from +0.37 (95% CI: 0.24-0.51) between FM and AGPH to +0.97 (95% CI: 0.80-1) between ME/CFS and FM. The highest familial correlation between an ID and FD was +0.83 (95% CI: 0.66-0.99) for MDD and ME/CFS.

CONCLUSIONS

There is a clear familial component to FDs, which is partially shared with IDs. This suggests that IDs and FDs share both genetic and family-environmental risk factors. Of the FDs, ME/CFS is most closely related to IDs.

Rome Foundation Working Team Report on overlap in disorders of gut-brain interaction

In patients with disorders of gut-brain interaction (DGBI), overlapping non-gastrointestinal conditions such as fibromyalgia, headaches, gynaecological and urological conditions, sleep disturbances and fatigue are common, as is overlap among DGBI in different regions of the gastrointestinal tract. These overlaps strongly influence patient management and outcome. Shared pathophysiology could explain this scenario, but details are not fully understood. This overlap has been shown to be of great relevance for DGBI. In addition, symptoms considered to be caused by a DGBI could have a detectable organic cause, and in patients with a diagnosed organic gastrointestinal disease, symptoms not clearly explained by the pathology defining this organic disease are common. Thus, the aims of this Rome Foundation Working Team Report were to review the literature on overlapping conditions among patients with paediatric and adult DGBI and, based on the available epidemiological and clinical evidence, make recommendations for the current diagnostic and therapeutic approach, and for future research. Specifically, we focused on other DGBI in the same or different gastrointestinal anatomical region(s), DGBI overlap with organic bowel diseases in remission, and DGBI overlap with non-gastrointestinal, non-structural conditions.

The role of the gut microbiome in disorders of gut-brain interaction

Disorders of Gut-Brain Interaction (DGBI) are widely prevalent and commonly encountered in gastroenterology practice. While several peripheral and central mechanisms have been implicated in the pathogenesis of DGBI, a recent body of work suggests an important role for the gut microbiome. In this review, we highlight how gut microbiota and their metabolites affect physiologic changes underlying symptoms in DGBI, with a particular focus on their mechanistic influence on GI transit, visceral sensitivity, intestinal barrier function and secretion, and CNS processing. This review emphasizes the complexity of local and distant effects of microbial metabolites on physiological function, influenced by factors such as metabolite concentration, duration of metabolite exposure, receptor location, host genetics, and underlying disease state. Large-scale in vitro work has elucidated interactions between host receptors and the microbial metabolome but there is a need for future research to integrate such preclinical findings with clinical studies. The development of novel, targeted therapeutic strategies for DGBI hinges on a deeper understanding of these metabolite-host interactions, offering exciting possibilities for the future of treatment of DGBI.

Omentin-1, a Protective Adipokine for Irritable Bowel Syndrome

Introduction

Irritable bowel syndrome (IBS) is characterized by patients' high level of suffering. There is increasing evidence for involvement of the immune system in this disease. Adipokines have been reported to be critical immunoregulators in many clinical conditions, including gastrointestinal (GI) inflammatory diseases. Our study aimed to investigate associations of omentin-1 (a newly discovered adipokine) with IBS.

Methods

In the current study, serum levels of omentin-1 were measured in 209 patients with IBS (including three subtypes) and 188 healthy controls by enzyme-linked immunosorbent assay (ELISA). The somatic symptoms of IBS were determined by the 5-item IBS symptoms severity score (IBS-SSS), quality of life (QOL) by 34-item IBS-QOL questionnaire, and psychological disorders by Patient Health Questionnaire (PHQ-9), Hospital Anxiety and Depression Scale (HADS), Visceral Sensitivity Index (VSI). Therapeutic effect of omentin-1 for IBS was investigated in a 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced IBS mouse model.

Results

We found that serum levels of omentin-1 were significantly decreased in patients with the diarrhea-predominant IBS (IBS-D) subtype (not the constipation or alternating subtype) compared to those in healthy subjects. Patients with lower serum omentin-1 levels suffered from higher severity of somatic symptoms (abdominal pain and distention, flatulence, rumbling), lower QOL, and worse psychological status. In a one-year follow-up, serum omentin-1 levels showed potential to reflect the disease progression. Additionally, lower omentin-1 levels were found to be accompanied with higher levels of serum pro-inflammatory cytokine concentrations in patients with IBS-D. Supplement of omentin-1 was protective against visceral hypersensitivity and mucosal inflammation in an IBS mouse model.

Discussion

Our findings highlight the potential value of serum omentin-1 levels as an innovative biomarker in IBS, emphasizing its significance in improving clinical treatment and management of the disease.

Chinese Herbal Medicine for Irritable Bowel Syndrome: A Perspective of Local Immune Actions

Irritable bowel syndrome (IBS) is the functional gastrointestinal disorder, characterized by abdominal pain and altered bowel habits. The interest in intestinal immune activation as a potential disease mechanism for IBS has increased exponentially in recent years. This study was designed to summarize the Chinese herbal medicine (CHM) that potentially exert protective effects against IBS through inhibition of intestinal immune activation. We detailed the current evidence that immune activation contributes to the pathology of IBS and discussed the potential mechanisms involved. Then, therapeutic effects and possible mechanisms related to immune response of herbal medicine prescriptions, extracts, and monomers were analyzed. The reasons leading to the aberrant and persistent immune activation noted in IBS are mainly associated with the increased number of mast cells, CD3[Formula: see text] T cells, and CD4[Formula: see text] T cells. The mechanisms mainly focused on the gut microbiota disorder induced alteration of the PGE2/COX2/SERT/5-HT, TLR4/MyD88/NF-κB, and BDNF/TrkB pathways. Most of the CHM alleviated IBS through interventions of intestinal immune activation via gut microbiota related to the TLR4/MyD88/NF-κB and SCF/c-kit pathways. We hope this review will provide some clues for the further development of novel candidate agents for IBS and other intestinal immune disorders.

Multiple Aspects of Irritable Bowel Syndrome and the Role of the Immune System: An Overview of Systematic Reviews with a Focus on Polyphenols

Irritable bowel syndrome (IBS) is a complex and often debilitating condition that significantly impacts the gastrointestinal system and the overall quality of life of those affected. IBS is characterized by a variety of distressing symptoms, including cramping, abdominal pain, and irregular bowel movements, underlined by an intricate interplay of immune system dysfunction in its pathology. Numerous studies highlight an increased cellular immune response, with elevated levels of proinflammatory cytokines, mucosal alterations due to immune imbalance, and visceral hypersensitivity. Notably, studies indicate increased levels of proinflammatory cytokines, immune imbalances that lead to mucosal changes, and heightened visceral sensitivity. The roles of effector and regulatory T cells are particularly intriguing, as their modification appears to amplify inflammation and may even contribute to autoimmune disorders. This overview of systematic reviews explores the connections between IBS and immune responses, with a focus on immune cell alterations and proliferation of lymphocytes and mast cells in affected individuals. Furthermore, we explore various aspects of IBS management, including its pharmacological approaches. A systematic search of PubMed and Web of Science yielded 676 articles, which were ultimately narrowed down to 9 key studies that met our inclusion criteria. These studies collectively underscore the activation of the immune system with the degranulation of the mast cells in patients with IBS, where the release of inflammatory mediators can compromise intestinal permeability, exacerbating symptoms further. Additionally, we examine the multifaceted management strategies for IBS, emphasizing the potential therapeutic benefits of dietary polyphenols as antioxidants. The present study aims to enhance our understanding of IBS and offer insights into more effective treatment strategies for this challenging condition.

Role of Inflammation and Motility Disorders in the Development, Course and Consequences of Functional Gastrointestinal and Biliary Tract Diseases (Literature Review and Expert Panel Resolution)

   Aim: to present the results of the Expert Panel with a discussion of modern concepts of the pathogenesis of functional gastrointestinal diseases and the possibilities of multitarget therapy with trimebutine.

   Key points. Low-grade inflammation can be considered as a morphological substrate of functional diseases with an increase in activated mastocytes and eosinophils, T-helpers 2 and T-helpers 17 in the gastrointestinal mucosa. In the development in the content of visceral hypersensitivity, the functional connection between mastocytes and TRPV1-positive sensory endings of the vagus nerve is of great importance. Proinflammatory cytokines and matrix metalloproteinases can enter the systemic circulation, provoking the development of systemic manifestations. Increased levels of proinflammatory cytokines are supported by altered intestinal permeability and microbiota. Functional diseases are believed to modify the symptoms and course of concomitant organic diseases of the gastrointestinal tract (for example, functional diseases of the biliary tract may contribute to the development of cholelithiasis, pancreatitis). The peripheral μ-, κ- and δ-receptor agonist trimebutine (Trimedat®) regulates the production of enterohormones, modulates motility throughout the gastrointestinal tract and normalizes visceral sensitivity. The effectiveness of trimebutine in the treatment of functional disorders has been shown in various studies. Trimebutine helps reduce the production of proinflammatory cytokines, including interleukin-6.

   Conclusion. In the treatment of functional diseases of the gastrointestinal tract, trimebutine can be considered as a multitarget agent, since the drug helps to normalize motility, reduces the degree of visceral hypersensitivity, exhibits anti-inflammatory and neuroregenerative effects, and can also increase the effectiveness of treatment of concomitant diseases.

A Standardized Classification Scheme for Gastroduodenal Disorder Evaluation Using the Gastric Alimetry System: Prospective Cohort Study

Background and Aims

Gastric Alimetry™ (Alimetry, New Zealand) is a new clinical test for gastroduodenal disorders involving simultaneous body surface gastric electrical mapping and validated symptom profiling. Studies have demonstrated a range of distinct pathophysiological profiles, and a classification scheme is now required. We used Gastric Alimetry spectral and symptom profiles to develop a mechanism-based test classification scheme, then assessed correlations with symptom severity, psychometrics, and quality of life.

Methods

We performed a multicenter prospective cohort study of patients meeting the Rome IV criteria for functional dyspepsia and chronic nausea and vomiting syndromes. Patients underwent Gastric Alimetry profiling, and a standardized digital classification framework was devised and applied to separate patients into those with a) abnormal spectral analyses (ie aberrant gastric frequencies, amplitudes, and rhythms); and normal spectral analyses with b) symptoms correlated to gastric amplitude (subgroups: sensorimotor, postgastric, and activity-relieved), and c) symptoms independent of gastric amplitude (subgroups: continuous, meal-relieved, meal-induced).

Results

Two hundred ten patients were included (80% female, median age 37), of whom 169 met the criteria for chronic nausea and vomiting syndromes and 206 met the criteria for functional dyspepsia (79% meeting both criteria). Overall, 83% were phenotyped using the novel scheme, with 79/210 (37.6%) classified as having a spectral abnormality. Of the remainder, the most common phenotypes were "continuous pattern" (37, 17.6%), "meal-induced pattern" (28, 13.3%), and "sensorimotor pattern" (15, 7.1%). Symptom patterns independent of gastric amplitude were more strongly correlated with depression and anxiety (Patient Health Questionnaire 2: exp(β) 2.38, P = .024, State-Trait Anxiety Inventory Short-Form score: exp(β) 1.21, P = .021).

Conclusion

A mechanistic classification scheme for assessing gastroduodenal disorders is presented. Classified phenotypes showed independent relationships with symptom severity, quality of life, and psychological measures. The scheme is now being applied clinically and in research studies.

Gut mechanoimmunology: Shaping immune response through physical cues

The gut immune system embodies a complex interplay between the gut mucosal barrier, the host's immune cells, and gut microbiota. These components exist within a dynamic environment characterized by a variety of physical cues, e.g., compression, tension, shear stress, stiffness, and viscoelasticity. The physical cues can be modified under specific pathological conditions. Given their dynamic nature, comprehending the specific effects of these physical cues on the gut immune system is critical for pathological and therapeutic studies of intestinal immune-related diseases. This review aims to discuss how physical cues influence gut immunology by affecting the gut mucosal barrier, host immune cells, and gut microbiota, defining this concept as gut mechanoimmunology. This review seeks to highlight that an enhanced understanding of gut mechanoimmunology carries therapeutic implications, not only for intestinal diseases but also for extraintestinal diseases.

Discrete interplay of gut microbiota L-tryptophan metabolites in host biology and disease

The gut microbiota and the host maintain a conjoint relationship and together achieve optimal physiology via a multitude of interactive signalling cues. Dietary-derived L-tryptophan (L-trp) is enzymatically metabolized by the resident symbiotic gut microbiota to indole and various indole derivatives. Indole and indole metabolites secreted by the gut bacteria act locally in the intestinal cells as well as distally and modulate tissue-specific functions which are beneficial to the host. Functions attributed to these microbial indole metabolites in the host include regulation of intestinal permeability, immunity and mucosal roles, inflammation, and insulin sensitivity. On the other hand, dysregulation of gut microbiota L-trp metabolism compromises the optimal availability of indole and indole metabolites and can induce the onset of metabolic disorders, inflammation, liver steatosis, and decrease gut barrier integrity. Gut dysbiosis is regarded as one of the prime reasons for this deregulated microbial-derived indole metabolites. A number of indole metabolites from the gut bacteria have been identified recently displaying variable affinity towards xenobiotic nuclear receptors. Microbial metabolite mimicry concept can be used to design and develop novel indole-moiety-containing compounds with higher affinity towards the receptors and efficacy in preclinical studies. Such compounds may serve as therapeutic drugs in clinical trials in the future. In this article, I review L-trp metabolism in the host and gut microbiota and the various physiological functions, patho-physiologies associated with the microbial-released indole metabolites in the host, including the metabolite mimicry-based concept to develop tailored indole-containing novel experimental drugs.

Characterization of idiopathic chronic diarrhea and associated intestinal inflammation and preliminary observations of effects of vagal nerve stimulation in a non-human primate

BACKGROUND

Diarrhea is commonly associated with irritable bowel syndrome, inflammatory bowel disease, microscopic colitis, and other gastrointestinal dysfunctions. Spontaneously occurring idiopathic chronic diarrhea is frequent in rhesus macaques, but has not been used as a model for the investigation of diarrhea or its treatment. We characterized this condition and present preliminary data demonstrating that left vagal nerve stimulation provides relief.

METHODS

Stool consistency scores were followed for up to 12 years. Inflammation was assessed by plasma C-reactive protein, [18F]fluorodeoxyglucose (FDG) uptake, measured by positron emission tomography (PET), multiplex T cell localization, endoscopy and histology. The vagus was stimulated for 9 weeks in conscious macaques, using fully implanted electrodes, under wireless control.

KEY RESULTS

Macaques exhibited recurrent periods of diarrhea for up to 12 years, and signs of inflammation: elevated plasma C-reactive protein, increased bowel FDG uptake and increased mucosal T helper1 T-cells. The colon and distal ileum were endoscopically normal, and histology revealed mild colonic inflammation. Application of vagal nerve stimulation to conscious macaques (10 Hz, 30 s every 3 h; 24 h a day for 9 weeks) significantly reduced severity of diarrhea and also reduced inflammation, as measured by FDG uptake and C-reactive protein.

CONCLUSIONS AND INFERENCES

These macaques exhibit spontaneously occurring diarrhea with intestinal inflammation that can be reduced by VNS. The data demonstrate the utility of this naturally occurring primate model to study the physiology and treatments for chronic diarrhea and the neural control circuits influencing diarrhea and inflammation that are not accessible in human subjects.

Bioinformatics and LC-QTOF-MS based discovery of pharmacodynamic and Q-markers of Pitongshu against functional dyspepsia

ETHNOPHARMACOLOGICAL RELEVANCE

Pitongshu (PTS) is a clinically effective empirical formula for the treatment of FD. The efficacy and safety of PTS have been demonstrated in randomized, controlled, double-blind trials, but there is a lack of understanding of the systematic evaluation of the efficacy of PTS and its material basis.

OBJECTIVE

To investigate the efficacy of PTS in Functional dyspepsia (FD) mice and possible Q-markers.

METHOD

In this study, we used "irregular feeding + chronic unpredictable chronic stimulation" to establish a mice model of FD with hepatogastric disharmony. The efficacy of PTS was assessed from hair condition, behavioral, pain, gastrointestinal function, and serum 5-HT, GAS, MTL levels in mice by instillation of different doses of PTS. In addition, the composition of drugs in blood was analyzed by LC-QTOF-MS and potential Q-markers were selected by combining network pharmacology, molecular docking and actual content.

RESULT

Our study showed that different doses of PTS increased pain threshold and writhing latency, decreased the number of writhings, increased gastric emptying rate and small intestinal propulsion rate, decreased total acidity of gastric contents and gastric acid secretion, and increased serum levels of 5-HT, GAS, and MTL in mice to different degrees. Enrichment analysis showed that PTS may be anti-FD through multiple pathways such as Serotonergic synapse, thyroid hormone signaling pathway, cholinergic synapse, and dopaminergic synapse. In addition, potential active ingredient substances were explored by LC-QTOF-MS combined with bioinformatics. Combined with the actual contentselected six constituents, hesperidin, neohesperidin, naringin, paeoniflorin, magnolol and honokiol, possible as Q-markers.

CONCLUSION

PTS may exert its anti-FD effects through multi-component, multi-target and multi-pathway". Constituents, hesperidin, neohesperidin, naringin, paeoniflorin, magnolol and honokiol may be the Q-markers of its anti-FD effects.

Immune cell signatures and causal association with irritable bowel syndrome: A mendelian randomization study

BACKGROUND

The mucosal barrier's immune-brain interactions, pivotal for neural development and function, are increasingly recognized for their potential causal and therapeutic relevance to irritable bowel syndrome (IBS). Prior studies linking immune inflammation with IBS have been inconsistent. To further elucidate this relationship, we conducted a Mendelian randomization (MR) analysis of 731 immune cell markers to dissect the influence of various immune phenotypes on IBS. Our goal was to deepen our understanding of the disrupted brain-gut axis in IBS and to identify novel therapeutic targets.

AIM

To leverage publicly available data to perform MR analysis on 731 immune cell markers and explore their impact on IBS. We aimed to uncover immunophenotypic associations with IBS that could inform future drug development and therapeutic strategies.

METHODS

We performed a comprehensive two-sample MR analysis to evaluate the causal relationship between immune cell markers and IBS. By utilizing genetic data from public databases, we examined the causal associations between 731 immune cell markers, encompassing median fluorescence intensity, relative cell abundance, absolute cell count, and morphological parameters, with IBS susceptibility. Sensitivity analyses were conducted to validate our findings and address potential heterogeneity and pleiotropy.

RESULTS

Bidirectional false discovery rate correction indicated no significant influence of IBS on immunophenotypes. However, our analysis revealed a causal impact of IBS on 30 out of 731 immune phenotypes (P < 0.05). Nine immune phenotypes demonstrated a protective effect against IBS [inverse variance weighting (IVW) < 0.05, odd ratio (OR) < 1], while 21 others were associated with an increased risk of IBS onset (IVW ≥ 0.05, OR ≥ 1).

CONCLUSION

Our findings underscore a substantial genetic correlation between immune cell phenotypes and IBS, providing valuable insights into the pathophysiology of the condition. These results pave the way for the development of more precise biomarkers and targeted therapies for IBS. Furthermore, this research enriches our comprehension of immune cell roles in IBS pathogenesis, offering a foundation for more effective, personalized treatment approaches. These advancements hold promise for improving IBS patient quality of life and reducing the disease burden on individuals and their families.

The Neutrophil-to-Albumin Ratio (NAR): A Novel Index in Relation to Clinical Symptoms, Quality of Life, and Psychological Status in Diarrhea-Predominant Irritable Bowel Syndrome (IBS-D)

Introduction

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder characterized by chronic abdominal pain and alterations in bowel habits. Despite the importance of biomarkers in disease management, the quest for precise and non-invasive biomarkers for IBS continues.

Methods

This study focuses on investigating the clinical significance of the neutrophil-to-albumin ratio (NAR) as a potential biomarker in IBS. A cohort of 86 patients diagnosed with diarrhea-predominant IBS (IBS-D) and 106 healthy individuals were assessed for clinical symptoms, quality of life (QOL), psychological status, as well as serum and mucosal cytokine production.

Results

Our findings revealed that NAR levels were notably elevated in patients with IBS-D compared to healthy controls. Positive correlations were observed between NAR levels and IBS clinical symptoms, while negative correlations were noted with QOL. Additionally, NAR showed positive associations with anxiety and depression scores, along with significant relationships with cytokine production (serum IL-6, TNF-α, IL-1β, IL-17A, GM-CSF, IFN-γ, MCP-1; mucosal IL-6, TNF-α, IL-1β, IL-17A) in IBS-D. Interestingly, patients with lower baseline NAR levels demonstrated potentially better clinical outcomes.

Conclusion

The study underscores the potential utility of NAR as a novel biomarker in IBS, emphasizing its role in enhancing disease monitoring, understanding disease pathophysiology, and tailoring treatment strategies for patients with IBS-D.

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.

Clinical diagnosis, prevention, and treatment of neurodyspepsia syndrome using intelligent medicine

Against the backdrop of rapid social economy and scientific and technological development, intelligent medical technology expanded based on the Internet plays a crucial role in the innovation and development of the modern medical industry. Intelligent medical technology has completely changed the fixed medical methods of the past, and it can solve the isolated defects between various unit systems, greatly improving the overall informatization level of hospitals. This article analyzed the clinical diagnosis, prevention, and treatment of neurodyspepsia syndrome (NDS) in intelligent medicine. Dyspepsia can cause palpitations, vomiting, abdominal distension, dizziness, and other symptoms so that it can cause discomfort and pain in the middle or around the epigastric region. Therefore, it is necessary to make a correct diagnosis of neurodyspepsia in order to reduce the discomfort of patients. Intelligent medical technology is of great significance in improving patients' symptoms. This study sets up a control group and an experimental group for the experiment. The control group used conventional medication technology, while the experimental group used intelligent medical technology to analyze the patient samples taken. By comparing the factors that affect patients with NDS, it was found that the physical function score of the experimental group was 6.3% lower than that of the control group. Intelligent medical technology has high diagnostic efficiency and can achieve rapid diagnosis of NDS, meeting the clinical diagnosis and prevention requirements of NDS.

The Presence of Ganglionic Acetylcholine Receptor Antibodies in Sera from Patients with Functional Gastrointestinal Disorders: A Preliminary Study

BACKGROUND

Functional gastrointestinal disorders (FGIDs), including functional dyspepsia (FD) and irritable bowel syndrome (IBS), are characterized by chronic and recurrent gastrointestinal symptoms. Clinically, FD and IBS often resemble gastrointestinal dysmotility caused by autoimmune autonomic neuropathy. We examined the seropositive frequency of autoantibodies against ganglionic nicotinic acetylcholine receptors (gnAChRs) in patients presenting with FGIDs.

OBJECTIVE

To elucidate the seropositivity of gnAChR antibodies and the clinical features of seropositive FD and IBS.

MATERIALS AND METHODS

We measured autoantibodies against the gnAChR α3 and β4subunits using luciferase immunoprecipitation systems. Serum samples from patients with any autonomic symptoms were obtained from hospitals in Japan between January 2012 and August 2018 (1787 serum samples of 1381 patients). We selected FD and IBS patients and compared the clinical characteristics and prevalence of autonomic symptoms between those with seropositive and seronegative IBS and FD.

RESULTS

Nine IBS and two FD cases (one comorbid case with IBS) were found. We found four patients (36.4%) in whom gnAChR antibodies were positive in these eleven patients. Sicca symptoms were observed in three of four cases (75%) of seropositive FGID compared with zero of seven cases (0%) of seronegative FGID.

CONCLUSIONS

We found patients with gnAChR antibodies in FD and IBS patients. These data will be valuable for elucidating the pathophysiology of these FGIDs and developing new treatment strategies.

Putting Functional Gastrointestinal Disorders within the Spectrum of Inflammatory Disorders Can Improve Classification and Diagnostics of These Disorders

The spectrum, intensity, and overlap of symptoms between functional gastrointestinal disorders (FGIDs) and other gastrointestinal disorders characterize patients with FGIDs, who are incredibly different in their backgrounds. An additional challenge with regard to the diagnosis of FGID and the applicability of a given treatment is the ongoing expansion of the risk factors believed to be connected to these disorders. Many cytokines and inflammatory cells have been found to cause the continuous existence of a low level of inflammation, which is thought to be a basic pathophysiological process. The idea of the gut-brain axis has been created to offer a basic framework for the complex interactions that occur between the nervous system and the intestinal functions, including the involvement of gut bacteria. In this review paper, we intend to promote the hypothesis that FGIDs should be seen through the perspective of the network of the neuroendocrine, immunological, metabolic, and microbiome pathways. This hypothesis arises from an increased understanding of chronic inflammation as a systemic disorder, that is omnipresent in chronic health conditions. A better understanding of inflammation's role in the pathogenesis of FGIDs can be achieved by clustering markers of inflammation with data indicating symptoms, comorbidities, and psycho-social factors. Finding subclasses among related entities of FGIDs may reduce patient heterogeneity and help clarify the pathophysiology of this disease to allow for better treatment.

Quantification of Mucosal Mast Cells in the Gastrointestinal Tract: A Primer for Practicing Pathologists

CONTEXT.—

Mast cells are essential components of the immune system and play crucial pathogenetic roles in several digestive diseases, including mastocytic enterocolitis and eosinophilic gastrointestinal disorders. Pathologists have rarely been asked to evaluate the distribution and density of mast cells in gastrointestinal (GI) biopsy specimens. However, such requests are becoming more common because of an increasing awareness of the role of mast cells in functional GI disease and in both esophageal and nonesophageal eosinophilic gastrointestinal disorders.

OBJECTIVE.—

To provide pathologists with tools to incorporate the assessment of mast cells in the evaluation of esophageal, gastric, and intestinal specimens by developing a systematic approach to their evaluation, counting, and reporting.

DESIGN.—

This study consisted of a review of the literature followed by multiple consensus sessions to decide where to count mast cells and what a countable mast cell is.

RESULTS.—

We reviewed 135 papers addressing the content of mast cells in the digestive tract, selected 21 that detailed how cells were counted (microscope lens, area of high-power fields, locations evaluated, type of cells considered as countable), and summarized their data in a table. Then, drawing from both the acceptable literature and our own extensive experience, we reached a tentative consensus on: (1) the normal numbers in the different segments of the GI tract; (2) the morphology of countable mast cells; and (3) the locations and strategies for counting them.

CONCLUSIONS.—

The result is a set of suggestions for reporting mast cell counts, their distribution, and their location in a way clinicians can understand and use for management decisions.

Cryptosporidium and irritable bowel syndrome

Cryptosporidium is an apicomplexan parasite that causes gastrointestinal disease in a wide variety of hosts and is associated with waterborne outbreaks. Nonetheless, the parasite is underdiagnosed. Cryptosporidium has been proposed as an etiological cause of irritable bowel syndrome (IBS) in several studies. However, the exact mechanism of pathogenesis is unknown, and no direct link has been discovered. This review will discuss several parasite-induced modifications, such as immunological, microbiome, and metabolite modifications, as well as their interactions. To summarize, Cryptosporidium causes low inflammation, dysbiosis, and unbalanced metabolism, which leads to a lack of homeostasis in the intestine in a comparable pattern to postinfectious IBS.

A pathophysiologic framework for the overlap of disorders of gut-brain interaction and the role of the gut microbiome

The International Rome Committee defines Disorders of Gut-Brain Interactions (DGBI) based upon distinct combinations of chronic and/or recurrent unexplained gastrointestinal symptoms. Yet patients often experience overlapping DGBI. Patients with DGBI frequently also suffer from extraintestinal symptoms, including fatigue, sleep disturbances, anxiety, and depression. Patients with overlapping DGBI typically experience more severe GI symptoms and increased psychosocial burden. Concerning the pathophysiology, DGBI are associated with disruptions in gut motility, function of the brain and enteric neurons, immune function, and genetic markers, with recent findings revealing gut microbiome alterations linked to these mechanisms of DGBI. Emerging evidence summarized in this review suggests that the microbiome influences various established disease mechanisms of different DGBI groups. Overall, changes in the gastrointestinal microbiome do not seem to be linked to a specific DGBI subgroup but may play a key role in the manifestation of different DGBI and, subsequently, overlap of DGBI. Understanding these shared mechanisms and the role of the gastrointestinal microbiome, particularly for overlapping DGBI, might aid in developing more precise diagnostic criteria and treatment strategies while developing personalized interventions that target specific mechanisms to improve patient outcomes.

Gut–Brain Axis, Microbiota and Probiotics—Current Knowledge on Their Role in Irritable Bowel Syndrome: A Review

Irritable bowel syndrome (IBS) is a common digestive disorder with a significant impact on both individuals and society in terms of quality of life and healthcare costs. A growing body of research has identified various communication pathways between the microbiota and the brain in relation to motility disorders, with the gut–brain axis being key to the pathogenesis of IBS. Multiple factors contribute to the pathogenetic pathways in IBS, including immune mechanisms, psychosocial factors, increased oxidative stress and pro-inflammatory cytokine release, as well as genetic and hormonal factors. Increased permeability of the normal intestinal barrier allows bacterial products to access the lamina propria, providing a mechanism for perpetuating chronic inflammation and characteristic symptoms. The microbiota influences inflammatory processes in IBS by altering the balance between pro-inflammatory factors and host defence. Probiotics modulate the pathophysiological mechanisms involved in IBS by influencing the composition of the microbiota and improving intestinal motility disorders, visceral hypersensitivity, immune function of the intestinal epithelium, metabolic processes in the intestinal lumen, dysfunction of the microbiota-GBA, and are recognised as effective and safe in IBS therapy. Our study aimed to provide a comprehensive overview of the relationship between the gut–brain axis, microbiota, and IBS, based on current information.

Palmitoylethanolamide counteracts high-fat diet-induced gut dysfunction by reprogramming microbiota composition and affecting tryptophan metabolism

Obesity is associated with gastrointestinal (GI) tract and central nervous system (CNS) disorders. High-fat diet (HFD) feeding-induced obesity in mice induces dysbiosis, causing a shift toward bacteria-derived metabolites with detrimental effects on metabolism and inflammation: events often contributing to the onset and progression of both GI and CNS disorders. Palmitoylethanolamide (PEA) is an endogenous lipid mediator with beneficial effects in mouse models of GI and CNS disorders. However, the mechanisms underlining its enteroprotective and neuroprotective effects still need to be fully understood. Here, we aimed to study the effects of PEA on intestinal inflammation and microbiota alterations resulting from lipid overnutrition. Ultramicronized PEA (30 mg/kg/die per os) was administered to HFD-fed mice for 7 weeks starting at the 12th week of HFD regimen. At the termination of the study, the effects of PEA on inflammatory factors and cells, gut microbial features and tryptophan (TRP)-kynurenine metabolism were evaluated. PEA regulates the crosstalk between the host immune system and gut microbiota via rebalancing colonic TRP metabolites. PEA treatment reduced intestinal immune cell recruitment, inflammatory response triggered by HFD feeding, and corticotropin-releasing hormone levels. In particular, PEA modulated HFD-altered TRP metabolism in the colon, rebalancing serotonin (5-HT) turnover and reducing kynurenine levels. These effects were associated with a reshaping of gut microbiota composition through increased butyrate-promoting/producing bacteria, such as Bifidobacterium, Oscillospiraceae and Turicibacter sanguinis, with the latter also described as 5-HT sensor. These data indicate that the rebuilding of gut microbiota following PEA supplementation promotes host 5-HT biosynthesis, which is crucial in regulating intestinal function.

Overactive bladder syndrome symptoms in youth with abdominal pain-associated disorders of gut-brain interaction

The purpose of the current study was to assess the frequency of overactive bladder syndrome (OBS) symptoms and their relationship to gastrointestinal symptoms in youth with abdominal pain-associated disorders of gut-brain interaction (AP-DGBI). This is a retrospective study of 226 youth diagnosed with an AP-DGBI. As part of standard care, all patients completed a symptom questionnaire regarding gastrointestinal and non-gastrointestinal symptoms including increased urinary frequency, nighttime urination, and urinary urgency. Overall, 54% of patients reported at least one OBS symptom. Increased frequency of urination was reported by 19%, urinary urgency by 34%, and nighttime urination by 36%. Increased frequency of urination and urinary urgency were associated with a change in stool form, a change in stool frequency, and in those fulfilling criteria for IBS. Increased frequency of urination was reported more frequently in those reporting predominantly loose stools (33% vs. 12%). Urinary symptoms are common in youth with AP-DGBI. Increased urinary frequency and urinary urgency are specifically associated with IBS, with increased urinary frequency being primarily associated with diarrhea predominant IBS. Further studies are needed to determine the impact of OBS on AP-DGBI severity and quality of life, and whether they impact DGBI treatment.

Managing pain in irritable bowel syndrome: current perspectives and best practice

INTRODUCTION

Irritable bowel syndrome (IBS) is characterized by chronic symptoms (>6 months) of abdominal pain in combination with a disturbed bowel habit. There is an association between the intensity of abdominal pain and the need for health care utilization. A bidirectionally disordered gut-brain interaction is central in the pathophysiology of IBS where a number of factors, gastrointestinal and non-gastrointestinal, can contribute to the illness experience. In order to treat abdominal pain in IBS, mapping these factors in a multidimensional clinical profile is helpful.

AREAS COVERED

This review covers basic epidemiology and pathophysiology of abdominal pain in IBS, the diagnostic approach, and a multidimensional treatment model where the management of abdominal pain is in focus.

EXPERT OPINION

A personalized treatment of abdominal pain in IBS is possible in patients who understand the diagnosis, the potential of therapies used, and where a good continuity in the patient-doctor relationship is established.

A distinctive profile of family genetic risk scores in a Swedish national sample of cases of fibromyalgia, irritable bowel syndrome, and chronic fatigue syndrome compared to rheumatoid arthritis and major depression

BACKGROUND

Functional somatic disorders (FSD) feature medical symptoms of unclear etiology. Attempts to clarify their origin have been hampered by a lack of rigorous research designs. We sought to clarify the etiology of the FSD by examining the genetic risk patterns for FSD and other related disorders.

METHODS

This study was performed in 5 829 186 individuals from Swedish national registers. We quantified familial genetic risk for FSD, internalizing disorders, and somatic disorders in cases of chronic fatigue syndrome (CFS), fibromyalgia (FM), and irritable bowel syndrome (IBS), using a novel method based on aggregate risk in first to fifth degree relatives, adjusting for cohabitation. We compared these profiles with those of a prototypic internalizing psychiatric - major depression (MD) - and a somatic/autoimmune disorder: rheumatoid arthritis (RA).

RESULTS

Patients with FM carry substantial genetic risks not only for FM, but also for pain syndromes and internalizing, autoimmune and sleep disorders. The genetic risk profiles for IBS and CFS are also widely distributed although with lower average risks. By contrast, genetic risk profiles of MD and RA are much more restricted to related conditions.

CONCLUSION

Patients with FM have a relatively unique family genetic risk score profile with elevated genetic risk across a range of disorders that differs markedly from the profiles of a classic autoimmune disorder (RA) and internalizing disorder (MD). A similar less marked pattern of genetic risks was seen for IBS and CFS. FSD arise from a distinctive pattern of genetic liability for a diversity of psychiatric, autoimmune, pain, sleep, and functional somatic disorders.

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.

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.

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.

HLA-A and HLA-B genes are involved in the pathogenesis of IBS

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder. The pathogenesis of IBS has not yet been fully elucidated, and the relationship between human leukocyte antigen (HLA) class I molecules and IBS is not clear. The present case-control study investigated the correlation between HLA-A and HLA-B genes and IBS. Peripheral blood samples were collected from 102 IBS patients and 108 healthy volunteers at Nanning First People's Hospital. DNA was extracted using a routine procedure, and HLA-A and HLA-B gene polymorphisms were identified by polymerase chain reaction with sequence-specific primers to determine the genotype and distribution frequency of HLA-A and HLA-B in IBS patients and healthy controls. Susceptibility and protective genes for IBS were identified using univariate and multivariate analyses. The frequency of HLA-A11 gene expression in the IBS group was significantly higher than that in the healthy control group, while the frequencies of HLA-A24, 26, and 33 gene expression were significantly higher in the healthy control group than in the IBS group (all P < .05). The frequencies of HLA-B56 and 75 (15) gene expression in the IBS group were significantly higher than those in the healthy control group, while the frequencies of HLA-B46 and 48 gene expression were significantly higher in the healthy control group than in the IBS group (all P < .05). Genes that may be related to the prevalence of IBS were included in the multivariate logistic regression, and the results suggested that the HLA-B75 (15) gene is a susceptibility gene for IBS (P = .031, odds ratio [OR] = 2.625, 95% confidence interval [CI]: 1.093-6.302), while the HLA-A24 (P = .003, OR = 0.308, 95% CI: 0.142-0.666), A26 (P = .009, OR = 0.162, 95% CI: 0.042-0.629), A33 (P = .012, OR = 0.173, 95% CI: 0.044-0.679), and B48 (P = .008, OR = 0.051, 95% CI: 0.006-0.459) genes are protective genes for IBS.

Probiotics in Functional Dyspepsia

Functional dyspepsia (FD) is a common disorder in everyday clinical practice identified nowadays as a multi-factorial, difficult to treat condition with a significant burden on patients' quality of life (QoL) and healthcare systems worldwide. Despite its high prevalence in the general population, the precise etiology of the disorder remains elusive, with its pathophysiological spectrum evolving over time, including variable potential mechanisms, i.e., impaired gastric accommodation, gastric motor disorders, hypersensitivity to gastric distention, disorders of the brain-gut axis, as well as less evident ones, i.e., altered duodenal microbiota composition and genetic susceptibility. In light of these implications, a definitive, universal treatment that could be beneficial for all FD patients is not available yet. Recently, probiotics have been suggested to be an effective therapeutic option that could alleviate gastrointestinal symptoms in patients with Irritable Bowel Syndrome (IBS), potentially due to anti-inflammatory properties or by modulating the complex bidirectional interactions between gastrointestinal microbiota and host crosstalk; however, their impact on the multiple aspects of FD remains ambiguous. In this review, we aim to summarize all currently available evidence for the efficacy of probiotics as a novel therapeutic approach for FD.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusion

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

Gastroparesis and Functional Dyspepsia: Spectrum of Gastroduodenal Neuromuscular Disorders or Unique Entities?

Gastroparesis is defined by delayed gastric emptying in the absence of mechanical obstruction of the stomach. Patients experience symptoms of nausea, vomiting, abdominal pain, fullness, and early satiety. The recognition of the disorder has progressed due to availability of gastric emptying scintigraphy and advancements made in understanding its pathophysiology and treatment options. The clinical presentation and treatment of gastroparesis overlap with a more commonly recognized disorder of gut-brain interaction, functional dyspepsia. Recent studies have reenergized the discussion whether these two are separate entities or perhaps reflect a spectrum of gastroduodenal neuromuscular disorders. The societal guidelines conflict on the utility of gastric emptying scintigraphy in assessment of patients with upper gastrointestinal symptoms. A better appraisal of similarities and differences between gastroparesis and functional dyspepsia will allow targeted treatment for these disorders. This is particularly important as specific pharmacological and endoscopic treatment options are being developed for gastroparesis which are unlikely to be helpful for functional dyspepsia. This review makes the case for considering these disorders in a spectrum where identification of both would most ideally position us toward providing the optimal clinical care.

Post COVID-19 irritable bowel syndrome

OBJECTIVES

The long-term consequences of COVID-19 infection on the gastrointestinal tract remain unclear. Here, we aimed to evaluate the prevalence of gastrointestinal symptoms and post-COVID-19 disorders of gut-brain interaction after hospitalisation for SARS-CoV-2 infection.

DESIGN

GI-COVID-19 is a prospective, multicentre, controlled study. Patients with and without COVID-19 diagnosis were evaluated on hospital admission and after 1, 6 and 12 months post hospitalisation. Gastrointestinal symptoms, anxiety and depression were assessed using validated questionnaires.

RESULTS

The study included 2183 hospitalised patients. The primary analysis included a total of 883 patients (614 patients with COVID-19 and 269 controls) due to the exclusion of patients with pre-existing gastrointestinal symptoms and/or surgery. At enrolment, gastrointestinal symptoms were more frequent among patients with COVID-19 than in the control group (59.3% vs 39.7%, p<0.001). At the 12-month follow-up, constipation and hard stools were significantly more prevalent in controls than in patients with COVID-19 (16% vs 9.6%, p=0.019 and 17.7% vs 10.9%, p=0.011, respectively). Compared with controls, patients with COVID-19 reported higher rates of irritable bowel syndrome (IBS) according to Rome IV criteria: 0.5% versus 3.2%, p=0.045. Factors significantly associated with IBS diagnosis included history of allergies, chronic intake of proton pump inhibitors and presence of dyspnoea. At the 6-month follow-up, the rate of patients with COVID-19 fulfilling the criteria for depression was higher than among controls.

CONCLUSION

Compared with controls, hospitalised patients with COVID-19 had fewer problems of constipation and hard stools at 12 months after acute infection. Patients with COVID-19 had significantly higher rates of IBS than controls.

TRIAL REGISTRATION NUMBER

NCT04691895.

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.

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

BACKGROUND

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

METHODS

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

KEY RESULTS

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

CONCLUSIONS AND INFERENCES

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

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.

Multi-omics analysis reveals the metabolic regulators of duodenal low-grade inflammation in a functional dyspepsia model

Several gastrointestinal phenotypes and impairment of duodenal mucosal barrier have been reported in clinical studies in patients with functional dyspepsia (FD). Due to the preferential colonization of the mucosa, intestinal microbes and their metabolites are commonly involved in host metabolism and immune responses. However, there are no studies on the intertwined correlation among multi-level data. For more comprehensive illustrating, a multi-omics analysis focusing on the duodenum was performed in the FD rat model. We found that differential microbiomes in the duodenum were significantly correlated with the biosynthesis of lipopolysaccharide and peptidoglycan. The innate immune response-related genes, which were upregulated in the duodenum, were associated with the TLR2/TLR4-NFκB signaling pathway. More importantly, arachidonyl ethanolamide (anandamide, AEA) and endocannabinoid analogues showed linear relationships with the FD phenotypes. Taken together, multi-level data from microbiome, transcriptome and metabolome reveal that AEA may regulate duodenal low-grade inflammation in FD. These results suggest an important cue of gut microbiome–endocannabinoid system axis in the pathogenesis of FD.

Circulating Pro-inflammatory Cytokines Do Not Explain Interindividual Variability in Visceral Sensitivity in Healthy Individuals

A role of the immune system in the pathophysiology of pain and hyperalgesia has received growing attention, especially in the context of visceral pain and the gut-brain axis. While acute experimental inflammation can induce visceral hyperalgesia as part of sickness behavior in healthy individuals, it remains unclear if normal plasma levels of circulating pro-inflammatory cytokines contribute to interindividual variability in visceral sensitivity. We herein compiled data from a tightly screened and well-characterized sample of healthy volunteers (N = 98) allowing us to assess associations between visceral sensitivity and gastrointestinal symptoms, and plasma concentrations of three selected pro-inflammatory cytokines (i.e., TNF-α, IL-6, and IL-8), along with cortisol and stress-related psychological variables. For analyses, we compared subgroups created to have distinct pro-inflammatory cytokine profiles, modelling healthy individuals at putative risk or resilience, respectively, for symptoms of the gut-brain axis, and compared them with respect to rectal sensory and pain thresholds and subclinical GI symptoms. Secondly, we computed multiple regression analyses to test if circulating pro-inflammatory markers predict visceral sensitivity in the whole sample. Despite pronounced subgroup differences in pro-inflammatory cytokine and cortisol concentrations, we observed no differences in measures of visceroception. In regression analyses, cytokines did not emerge as predictors. The pain threshold was predicted by emotional state and trait variables, especially state anxiety, together explaining 10.9% of the variance. These negative results do not support the hypothesis that systemic cytokine levels contribute to normal interindividual variability in visceroception in healthy individuals. Trajectories to visceral hyperalgesia as key marker in disorders of gut-brain interactions likely involve complex interactions of biological and psychological factors in keeping with a psychosocial model. Normal variations in systemic cytokines do not appear to constitute a vulnerability factor in otherwise healthy individuals, calling for prospective studies in at risk populations.

Somatosensory Profiles Differentiate Pain and Psychophysiological Symptoms Among Young Adults With Irritable Bowel Syndrome: A Cluster Analysis

OBJECTIVE

The aim of this study was to investigate if somatosensory profiles can differentiate pain and psychophysiological symptoms among young adults with irritable bowel syndrome (IBS).

METHODS

We performed a cluster analysis of data collected from a randomized clinical trial of 80 IBS patients and 21 age-matched healthy controls (HCs) to stratify pain and symptoms among young adults with IBS by their peripheral sensory profiles. Data of quantitative sensory testing and IBS-related pain and symptoms were collected at baseline and 6-week and 12-week follow-ups.

RESULTS

Using the K-means method, IBS patients were classified into 2 clusters, the "IBS normal threshold" (IBS-NT) and the "IBS increased threshold" (IBS-IT). The IBS-NT cluster had a similar pain threshold as the HCs, and the IBS-IT cluster had an increased threshold of somatic pain perception (lower cold pain threshold, higher heat pain threshold, and higher pressure pain threshold, all P<0.001) than HCs. Compared with the IBS-NT cluster, the IBS-IT cluster reported higher levels of IBS-related pain intensity, anxiety, fatigue, and sleep disturbance over the 3 visits (all P<0.05).

DISCUSSION

Young adults with IBS fell into 2 clusters, one with a similar sensory threshold as the HCs and another with an increased pain threshold, who reported higher pain intensity and more severe symptoms. Somatic sensory profiles should be integrated into further personalized self-management intervention among patients with IBS.

Saccharomyces boulardii, a yeast probiotic, inhibits gut motility through upregulating intestinal serotonin transporter and modulating gut microbiota

Saccharomyces boulardii (Sb) is a widely used fungal probiotic in treating various digestive diseases, including irritable bowel syndrome (IBS). However, the specific mechanisms of Sb relieving IBS remain unclear. The abnormal serotonin transporter (SERT) / 5-hydroxytryptamine (5-HT) system could cause disordered gastrointestinal sensation and motility, which closely related to IBS pathogenesis. The aim of this study was to explore the effects and mechanisms of Sb on regulating gut motility. Sb supernatant (SbS) was administered to intestinal epithelial cells and mice. SbS upregulated SERT expression via enhancing heparin-binding epidermal growth factor (HB-EGF) release to activate epidermal growth factor receptor (EGFR). EGFR kinase inhibitor treatment or HB-EGF siRNA transfection in cells blocked SbS upregulating SERT. Consistently, SbS-treated mice presented inhibited gut motility, and EGFR activation and SERT upregulation were found. Moreover, 16 S rDNA sequence presented an evident decrease in Firmicutes / Bacteroidetes ratio in SbS group. In genus level, SbS reduced Escherichia_Shigella, Alistipes, Clostridium XlVa, and Saccharibacteria_genera_incertae_sedis, meanwhile, increased Parasutterella. The abundance of Saccharibacteria_genera_incertae_sedis positively correlated with defecation parameters and intestinal 5-HT content. Fecal microbiota transplantation showed that SbS could modulate gut microbiota to influence gut motility. Interestingly, elimination of gut microbiota with antibiotic cocktail did not entirely block SbS regulating gut motility. Furthermore, SbS administration to IBS-D mice significantly upregulated SERT and inhibited gut motility. In conclusion, SbS could upregulate SERT by EGFR activation, and modulate gut microbiota to inhibit gut motility. This finding would provide more evidence for the application of this yeast probiotic in IBS and other diarrheal disorders.

Mast cell mediation of visceral sensation and permeability in irritable bowel syndrome

Abnormalities of mast cell structure or function may play prominent roles in irritable bowel syndrome (IBS) symptom genesis. Mast cells show close apposition to sensory nerves and release bioactive substances in response to varied stimuli including infection, stress, and other neuroendocrine factors. Most studies focus on patients who develop IBS after enteric infection or who report diarrhea-predominant symptoms. Three topics underlying IBS pathogenesis have been emphasized in recent investigations. Visceral hypersensitivity to luminal stimulation is found in most IBS patients and may contribute to abdominal pain. Mast cell dysfunction also may disrupt epithelial barrier function which alters mucosal permeability potentially leading to altered bowel function and pain. Mast cell products including histamine, proteases, prostaglandins, and cytokines may participate in hypersensitivity and permeability defects, especially with diarrhea-predominant IBS. Recent experimental evidence indicates that the pronociceptive effects of histamine and proteases are mediated by the generation of prostaglandins in the mast cell. Enteric microbiome interactions including increased mucosal bacterial translocation may activate mast cells to elicit inflammatory responses underlying some of these pathogenic effects. Therapies to alter mast cell activity (mast cell stabilizers) or function (histamine antagonists) have shown modest benefits in IBS. Future investigations will seek to define patient subsets with greater potential to respond to therapies that address visceral hypersensitivity, epithelial permeability defects, and microbiome alterations secondary to mast cell dysfunction in IBS.

Global Research Trends in Irritable Bowel Syndrome: A Bibliometric and Visualized Study

Background

There are about 10–23% of adults worldwide suffering from irritable bowel syndrome (IBS). Over the past few decades, there are many aspects of uncertainty regarding IBS leading to an ongoing interest in the topic as reflected by a vast number of publications, whose heterogeneity and variable quality may challenge researchers to measure their scientific impact, to identify collaborative networks, and to grasp actively researched themes. Accordingly, with help from bibliometric approaches, our goal is to assess the structure, evolution, and trends of IBS research between 2007 and 2022.

Methods

The documents exclusively focusing on IBS from 2007 to 2022 were retrieved from the Science Citation Index Expanded of the Web of Science Core Collection. The annual productivity of IBS research, and the most prolific countries or regions, authors, journals and resource-, intellectual- and knowledge-sharing in IBS research, as well as co-citation analysis of references and keywords were analyzed through Microsoft Office Excel 2019, CiteSpace, and VOSviewer.

Results

In total, 4,092 publications were reviewed. The USA led the list of countries with the most publications (1,226, 29.96%). Mayo Clinic contributed more publications than any other institution (193, 4.71%). MAGNUS SIMREN stood out as the most active and impactful scholar with the highest number of publications and the greatest betweenness centrality value. The most high-yield journal in this field was Neurogastroenterology and motility: the official journal of the European Gastrointestinal Motility Society (275, 6.72%). Gastroenterology had the most co-citations (3,721, 3.60%). Keywords with the ongoing strong citation bursts were chromogranin A, rat model, peptide YY, gut microbiota, and low-FODMAP diet, etc.

Conclusion

Through bibliometric analysis, we gleaned deep insight into the current status of literature investigating IBS for the first time. These findings will be useful to scholars interested in understanding the key information in the field, as well as identifying possible research frontiers.

Symptoms Compatible with Rome IV Functional Bowel Disorder in Patients with Ankylosing Spondylitis

OBJECTIVES

To determine the frequency of symptoms meeting Rome IV functional bowel disorder (FBD) in patients with ankylosing spondylitis (AS), investigate factors associated with FBD symptoms, and assess whether having FBD symptoms might influence AS disease activity.

METHODS

In this cross-sectional study, we enrolled 153 AS patients without known colonic ulcer and 56 sex- and age-matched controls to evaluate FBD (or its subtypes) symptoms. Disease characteristics were also evaluated in AS group.

RESULTS

Sixty (39.2%) of 153 AS patients had FBD symptoms, which was more prevalent than controls (23.2%). Besides, symptoms compatible with irritable bowel syndrome (IBS) and chronic diarrhea were detected in 18 and 43 AS patients respectively. For AS group, multivariable logistic regression analyses showed that symptoms of FBD, IBS, and chronic diarrhea were negatively associated with using non-steroidal anti-inflammatory drug (NSAID), and positively associated with comorbid fibromyalgia, respectively. In exploration about effects of FBD (or its subtypes) symptoms on AS disease activity by multivariable linear regression analyses, FBD symptoms and chronic diarrhea had universal positive associations with assessments of AS disease characteristics respectively.

CONCLUSION

Patients with AS had frequent symptoms compatible with FBD, IBS, and chronic diarrhea, proportions of which were lower in those with NSAID-use. The improvement of FBD symptoms and chronic diarrhea might be conducive to disease status of AS patients.

A survey of functional dyspepsia in 361,360 individuals: Phenotypic and genetic cross-disease analyses

BACKGROUND

Functional dyspepsia (FD) is a common gastrointestinal condition of poorly understood pathophysiology. While symptoms' overlap with other conditions may indicate common pathogenetic mechanisms, genetic predisposition is suspected but has not been adequately investigated.

METHODS

Using healthcare, questionnaire, and genetic data from three large population-based biobanks (UK Biobank, EGCUT, and MGI), we surveyed FD comorbidities, heritability, and genetic correlations across a wide spectrum of conditions and traits in 10,078 cases and 351,282 non-FD controls of European ancestry.

KEY RESULTS

In UK Biobank, 281 diagnoses were detected at increased prevalence in FD, based on healthcare records. Among these, gastrointestinal conditions (OR = 4.0, p < 1.0 × 10-300 ), anxiety disorders (OR = 2.3, p < 1.4 × 10-27 ), ischemic heart disease (OR = 2.2, p < 2.3 × 10-76 ), and infectious and parasitic diseases (OR = 2.1, p = 1.5 × 10-73 ) showed strongest association with FD. Similar results were obtained in an analysis of self-reported conditions and use of medications from questionnaire data. Based on a genome-wide association meta-analysis of genotypes across all cohorts, FD heritability was estimated close to 5% ( h SNP 2  = 0.047, p = 0.014). Genetic correlations indicate FD predisposition is shared with several other diseases and traits (rg  > 0.344), mostly overlapping with those also enriched in FD patients. Suggestive (p < 5.0 × 10-6 ) association with FD risk was detected for 13 loci, with 2 showing nominal replication (p < 0.05) in an independent cohort of 192 FD patients.

CONCLUSIONS & INFERENCES

FD has a weak heritable component that shows commonalities with multiple conditions across a wide spectrum of pathophysiological domains. This new knowledge contributes to a better understanding of FD etiology and may have implications for improving its treatment.

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.

The difference of disrupted rhythms of life, work and entertainment between patients with FGIDs and healthy people and their associations with psychological disorders under COVID-19 pandemic

AIMS

To investigate the differences in disrupted rhythms between healthy people and patients with functional gastrointestinal disorders (FGIDs) and their associations with mood disorders during the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

The rhythm scales were composed of subscales 1 and 2 for the assessment of life-work and entertainment rhythms, respectively; Zung's Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) were used to assess mood disorders.

RESULTS

A total of 671 patients with FGIDs and 4373 healthy people successfully participated. The scores of subscales 1 and 2 for patients with FGIDs were significantly higher than those for healthy people (p < .005). The SAS and SDS scores, their prevalence rates were significantly higher than those for the healthy group (all p < .001). Health status, current occupation, life-work rhythm, SDS, and SAS were independent related factors of FGIDs. The score of life-work-entertainment rhythm was significantly positively correlated with SDS and SAS (both p < .001).

CONCLUSION

Disrupted rhythms in patients with FGIDs under the COVID-19 pandemic were more frequently and significantly positively associated with mood disorders.

Immune responses in the irritable bowel syndromes: time to consider the small intestine

BACKGROUND

Irritable bowel syndrome (IBS) is considered a disorder of gut-brain interaction (DGBI), presenting as chronic abdominal pain and altered defaecation. Symptoms are often food related. Much work in the field has focused on identifying physiological, immune and microbial abnormalities in the colon of patients; however, evidence of small intestinal immune activation and microbial imbalance has been reported in small studies. The significance of such findings has been largely underappreciated despite a growing body of work implicating small intestinal homeostatic imbalance in the pathogenesis of DGBIs.

MAIN TEXT

Small intestinal mechanosensation is a characteristic feature of IBS. Furthermore, altered small intestinal barrier functions have been demonstrated in IBS patients with the diarrhoea-predominant subtype. Small intestinal bacterial overgrowth and increased populations of small intestinal mast cells are frequently associated with IBS, implicating microbial imbalance and low-grade inflammation in the pathogenesis of IBS. Furthermore, reports of localised food hypersensitivity responses in IBS patients implicate the small intestine as the site of immune-microbial-food interactions.

CONCLUSIONS

Given the association of IBS symptoms with food intake in a large proportion of patients and the emerging evidence of immune activation in these patients, the current literature suggests the pathogenesis of IBS is not limited to the colon but rather may involve dysfunction of the entire intestinal tract. It remains unclear if regional variation in IBS pathology explains the various symptom phenotypes and further work should consider the intestinal tract as a whole to answer this question.