The duodenal mucosa associated microbiome, visceral sensory function, immune activation and psychological comorbidities in functional gastrointestinal disorders with and without self-reported non-celiac wheat sensitivity

Probiotics supplementation during pregnancy or infancy on multiple food allergies and gut microbiota: a systematic review and meta-analysis

CONTEXT

Probiotics show promise in preventing and managing food allergies, but the impact of supplementation during pregnancy or infancy on children's allergies and gut microbiota remains unclear.

OBJECTIVE

This study aimed to assess the effects of maternal or infant probiotic supplementation on food allergy risk and explore the role of gut microbiota.

DATA SOURCES

A systematic search of databases (PubMed, Cochrane Library, Embase, and Medline) identified 37 relevant studies until May 20, 2023.

DATA EXTRACTION

Two independent reviewers extracted data, including probiotics intervention details, gut microbiota analysis, and food allergy information.

DATA ANALYSIS

Probiotics supplementation during pregnancy and infancy reduced the risk of total food allergy (relative risk [RR], 0.79; 95% CI, 0.63-0.99), cow-milk allergy (RR, 0.51; 95% CI, 0.29-0.88), and egg allergy (RR, 0.57; 95% CI, 0.39-0.84). Infancy-only supplementation lowered cow-milk allergy risk (RR, 0.69; 95% CI, 0.49-0.96), while pregnancy-only had no discernible effect. Benefits were observed with over 2 probiotic species, and a daily increase of 1.8 × 109 colony-forming units during pregnancy and infancy correlated with a 4% reduction in food allergy risk. Children with food allergies had distinct gut microbiota profiles, evolving with age.

CONCLUSIONS

Probiotics supplementation during pregnancy and infancy reduces food allergy risk and correlates with age-related changes in gut microbial composition in children.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023425988.

Deciphering the psychological tapestry of FGIDs: unveiling the impact of negative affect, rumination, and expression suppression

BACKGROUND

Functional Gastrointestinal Disorders (FGIDs) constitute a group of psychosomatic diseases characterized primarily by disruptions in the functioning of the digestive system, profoundly impacting the lives of affected individuals.

OBJECTIVE

This study aims to investigate the influence of negative affect (NA) on the gastrointestinal symptoms of FGID patients, as well as the mediating role of rumination and the regulatory effects of expression suppression (ES) as an emotional regulation strategy.

METHODS

A survey was conducted on 1000 patients (403M, 597F) with gastrointestinal disorders at a tertiary hospital using the negative affect subscale from the DS-14 (Type D Personality Scale), the Gastrointestinal Symptom Rating Scale (GSRS), the Rumination Response Scale (RRS), and the expression suppression subscale from the Gross-John Emotion Regulation Strategy.

RESULTS

Negative affect positively predicts FGIDs, with rumination mediating the relationship between NA and FGIDs. The emotional regulation strategy of expression suppression moderates the positive relationship between NA and rumination and the mediating effect of rumination.

CONCLUSION

NA exacerbates symptoms of FGIDs in individuals, and rumination further amplifies this effect, with the mediating influence evident across both high and low ES emotion regulation strategy groups.

Gluten Unraveled: Latest Insights on Terminology, Diagnosis, Pathophysiology, Dietary Strategies, and Intestinal Microbiota Modulations-A Decade in Review

A decade of research on gluten-related disorders (GRDs) is reviewed in this study, with a particular emphasis on celiac disease (CD) and non-celiac gluten sensitivity (NCGS). GRDs are triggered by the ingestion of gluten and gluten-like proteins found in wheat, barley, and rye. These proteins lead to intestinal damage in celiac disease, an autoimmune condition characterized by villous atrophy and a variety of gastrointestinal and extraintestinal symptoms. More enigmatic and less understood, NCGS involves symptoms similar to CD but without the immunological reaction or intestinal damage. Recent years have seen advances in the understanding of GRDs, particularly in connection to how intestinal microbiota influences disease progression and patient outcomes. The gluten-free diet (GFD) is still the standard therapy recommended for GRDs despite significant challenges, as discussed in this article. Precise diagnostic methods, patient education and dietary counseling are critical for improving patients' quality of life. The purpose of this review is to provide a more clear and up-to-date understanding of GRDs, and to help further research on this important topic.

The biogeography of the mucosa-associated microbiome in health and disease

Introduction

Little is known about the biogeography of the mucosa associated microbiome (MAM) in patients with inflammatory bowel disease (IBD) versus controls in different segments of the gastrointestinal tract, as well as the links between the MAM, gastrointestinal symptoms, and use of proton pump inhibitors (PPI).

Methods

We recruited 59 controls (without structural abnormalities and gastrointestinal symptoms), 44 patients with ulcerative colitis (UC) and 31 with Crohn's disease (CD). Biopsies from various segments of the upper and lower gastrointestinal tract were collected. Microbial composition was assessed via 16S rRNA gene amplicon analysis and the bacterial load of the mucosal biopsies were assessed via qPCR. The MAM was examined in the context of disease status, PPI usage, the severity of gastrointestinal symptoms, and the symptom response to a standardised nutrient challenge (SNC).

Results

Microbial communities of the MAM in the upper and lower gastrointestinal tract differed. IBD patients were characterised by relative and absolute depletion of numerous genera known to produce butyrate and/or propionate, with the largest differentiation being the depletion of Faecalibacterium in the lower gastrointestinal tract of CD patients. Notably, PPI users exhibited an enrichment of Faecalibacterium in the lower gastrointestinal tract. The severity of gastrointestinal symptoms, as well as the symptom response to the SNC, were significantly associated with MAM composition in the gastrointestinal tract.

Conclusion

The absolute and relative composition of the MAM is variable across different segments of the gastrointestinal tract. These quantitative changes indicates that MAM can be targeted in specific segments of the GI tract to improve patient outcomes.

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.

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.

TRAV26-2 T-Cell Receptor Expression Is Associated With Mucosal Lymphocyte Response to Wheat Proteins in Patients With Functional Dyspepsia

INTRODUCTION

An association between functional dyspepsia (FD) and wheat-containing foods has been reported in observational studies; however, an adaptive response has not been demonstrated. We examined whether antigens present in wheat could provoke a response from FD duodenal lymphocytes.

METHODS

Lamina propria mononuclear cells (LPMCs) were isolated from duodenal biopsies from 50 patients with FD and 23 controls. LPMCs were exposed to gluten (0.2 mg/mL) or gliadin (0.2 mg/mL) for 24 hours. Flow cytometry was performed to phenotype lymphocytes. Quantitative PCR was used to measure the expression of gliadin-associated T-cell receptor alpha variant ( TRAV ) 26-2.

RESULTS

In response to gliadin (but not gluten) stimulation, the effector Th2-like population was increased in FD LPMCs compared with that in controls and unstimulated FD LPMCs. Duodenal gene expression of TRAV26- 2 was decreased in patients with FD compared with that in controls. We identified a positive association between gene expression of this T-cell receptor variant and LPMC effector Th17-like cell populations in patients with FD, but not controls after exposure to gluten, but not gliadin.

DISCUSSION

Our findings suggest that gliadin exposure provokes a duodenal effector Th2-like response in patients with FD, supporting the notion that food antigens drive responses in some patients. Furthermore, these findings suggest that altered lymphocyte responses to wheat proteins play a role in FD pathogenesis.

Causal link between gut microbiota and four types of pancreatitis: a genetic association and bidirectional Mendelian randomization study

BACKGROUND

A number of recent observational studies have indicated a correlation between the constitution of gut microbiota and the incidence of pancreatitis. Notwithstanding, observational studies are unreliable for inferring causality because of their susceptibility to confounding, bias, and reverse causality, the causal relationship between specific gut microbiota and pancreatitis is still unclear. Therefore, our study aimed to investigate the causal relationship between gut microbiota and four types of pancreatitis.

METHODS

An investigative undertaking encompassing a genome-wide association study (GWAS) comprising 18,340 participants was undertaken with the aim of discerning genetic instrumental variables that exhibit associations with gut microbiota, The aggregated statistical data pertaining to acute pancreatitis (AP), alcohol-induced AP (AAP), chronic pancreatitis (CP), and alcohol-induced CP (ACP) were acquired from the FinnGen Consortium. The two-sample bidirectional Mendelian randomization (MR) approach was utilized. Utilizing the Inverse-Variance Weighted (IVW) technique as the cornerstone of our primary analysis. The Bonferroni analysis was used to correct for multiple testing, In addition, a number of sensitivity analysis methodologies, comprising the MR-Egger intercept test, the Cochran's Q test, MR polymorphism residual and outlier (MR-PRESSO) test, and the leave-one-out test, were performed to evaluate the robustness of our findings.

RESULTS

A total of 28 intestinal microflora were ascertained to exhibit significant associations with diverse outcomes of pancreatitis. Among them, Class Melainabacteria (OR = 1.801, 95% CI: 1.288-2.519, p = 0.008) has a strong causality with ACP after the Bonferroni-corrected test, in order to assess potential reverse causation effects, we used four types of pancreatitis as the exposure variable and scrutinized its impact on gut microbiota as the outcome variable, this analysis revealed associations between pancreatitis and 30 distinct types of gut microflora. The implementation of Cochran's Q test revealed a lack of substantial heterogeneity among the various single nucleotide polymorphisms (SNP).

CONCLUSION

Our first systematic Mendelian randomization analysis provides evidence that multiple gut microbiota taxa may be causally associated with four types of pancreatitis disease. This discovery may contribute significant biomarkers conducive to the preliminary, non-invasive identification of Pancreatitis. Additionally, it could present viable targets for potential therapeutic interventions in the disease's treatment.

Irritable bowel syndrome - controversies in diagnosis and management

INTRODUCTION

The irritable bowel syndrome (IBS) is the best-recognized disorder of gut brain interactions (DGBI). However, it is controversial if the Rome IV criteria iteration for IBS diagnosis is fit for purpose.

AREAS COVERED

This review critically evaluates Rome IV criteria for diagnosis of IBS and addresses clinical considerations in IBS treatment and management, including dietary factors, biomarkers, disease mimics, symptom severity, and subtypes. The role of diet in IBS is critically reviewed along with the influence of the microbiota, including small intestinal bacterial overgrowth.

EXPERT OPINION

Emerging data suggest the Rome IV criteria are more suitable for identifying severe IBS and least useful for sub-diagnostic patients who are still likely to benefit from IBS treatment. Despite convincing evidence that IBS symptoms are diet-driven and often postprandial, a relationship to eating is not a Rome IV diagnostic criterion. Few IBS biomarkers have been identified, suggesting the syndrome is too heterogeneous to be measured by a single marker, and combined biomarker, clinical, dietary, and microbial profiling may be needed for objective characterization. With many organic diseases mimicking and overlapping with IBS, it's important clinicians are knowledgable about this to mitigate the risk of missing comorbid organic intestinal disease and to optimally treat IBS symptoms.

Gastroparesis: The Complex Interplay with Microbiota and the Role of Exogenous Infections in the Pathogenesis of the Disease

Gastroparesis (GP) is a disorder of gastric functions that is defined by objective delayed gastric emptying in the absence of mechanical obstruction. This disease is characterized by symptoms such as nausea, post-prandial fullness, and early satiety. GP significantly impacts patients' quality of life and contributes to substantial healthcare expenses for families and society. However, the epidemiological burden of GP is difficult to evaluate, mainly due its significant overlap with functional dyspepsia (FD). GP and FD represent two similar diseases. The pathophysiology of both disorders involves abnormal gastric motility, visceral hypersensitivity, and mucosal inflammation. Moreover, both conditions share similar symptoms, such as epigastric pain, bloating, and early satiety. The latest evidence reveals that dysbiosis is directly or indirectly connected to gut-brain axis alterations, which are the basis of pathogenesis in both FD and GP. Furthermore, the role of microbiota in the development of gastroparesis was demonstrated by some clinical studies, which found that the use of probiotics is correlated with improvements in the gastric emptying time (GET). Infections (with viruses, bacteria, and protozoa) represent a proven etiology for GP but have not been sufficiently considered in current clinical practice. Previous viral infections can be found in about 20% of idiopathic GP cases. Moreover, delayed gastric emptying during systemic protozoal infections represents a huge concern for compromised patients, and few data exist on the topic. This comprehensive narrative review analyzes the relationship between microorganisms and GP. We explore, on the one hand, the correlation between gut microbiota dysbiosis and GP pathogenesis, including treatment implications, and, on the other hand, the association between exogenous infections and the etiology of the disease.