Impact of gluten consumption in patients with functional dyspepsia: A case-control study

Nutrition and Disorders of Gut-Brain Interaction

BACKGROUND

Disorders of gut-brain interaction (DGBIs) have a complex pathophysiology that is often characterized by a relationship between food ingestion and triggering of symptoms. Understanding of the underlying mechanisms and the role of nutrients as a therapeutic target are rapidly evolving.

AIMS AND METHODS

We performed a narrative review of the literature using the following keywords, their acronyms, and their associations: nutrients, disorders of gut-brain interaction; functional dyspepsia; malabsorption; irritable bowel syndrome; diarrhea; constipation.

RESULTS

Functional dyspepsia displayed a significant correlation between volume, fat and/or wheat abundance, chemical composition of ingested food and symptoms of early satiety, fullness and weight loss. Carbohydrate malabsorption is related to enzyme deficiency throughout the GI tract. Food composition and richness in soluble vs. non-soluble fibers is related to constipation and diarrhea. The elimination of fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) has a significant and non-unidirectional impact on irritable bowel syndrome (IBS) symptoms.

CONCLUSIONS

Food volume, nutritive and chemical composition, and its malabsorption are associated with symptom generation in DGBIs. Further multicenter, randomized-controlled clinical trials are needed to clarify the underlying pathophysiology.

The Role of Gluten in Gastrointestinal Disorders: A Review

Gluten is only partially digested by intestinal enzymes and can generate peptides that can alter intestinal permeability, facilitating bacterial translocation, thus affecting the immune system. Few studies addressed the role of diet with gluten in the development of intestinal inflammation and in other gastrointestinal disorders. The aim of this narrative review was to analyse the role of gluten in several gastrointestinal diseases so as to give a useful overview of its effectiveness in the prevention and management of these disorders.

Mast cells disrupt the duodenal mucosal integrity: Implications for the mechanisms of barrier dysfunction in functional dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a common functional gastrointestinal (GI) disorder, but its pathophysiology is poorly understood. Mast cells (MCs) may play a critical role in the development of FD. Therefore, the aim of this study was to investigate the effect of MCs on barrier function, tight junction (TJ) proteins and related signaling pathways.

METHODS

The expression of the TJ proteins claudin-8, ZO-1 and occludin in biopsy tissues from seven FD patients and five controls was assessed. Based on the in vivo results, we further investigated the effect of (1) MC degranulation in a coculture model of Caco-2/RBL-2H3 cells and tryptase in Caco-2 monolayers, (2) MC degranulation in the presence or absence of a PAR-2 antagonist and (3) MC degranulation in the presence or absence of an ERK1/2 signaling pathway inhibitor. The epithelial integrity of Caco-2 cell monolayers was assessed by measuring the transepithelial electrical resistance (TEER). The expression of TJ proteins was evaluated by western blotting, QT-PCR and immunostaining.

RESULTS

Epithelial claudin-8, ZO-1 and occludin protein expression were significantly reduced in tissues from FD patients compared with controls. MC degranulation and tryptase decreased the TEER and reduced the expression of TJ proteins in Caco-2 cell monolayers. A PAR-2 antagonist and an ERK1/2 signaling pathway inhibitor significantly reduced the effect of MC degranulation on the TEER and TJ protein expression in Caco-2 cell monolayers.

CONCLUSIONS

MCs disrupt duodenal barrier function by modulating the levels of TJ proteins, and the PAR-2 and ERK1/2 signaling pathways may mediate the pathogenesis of FD.

Exclusion Diets in Functional Dyspepsia

Functional dyspepsia represents one of the most common and prevalent disorders of the brain–gut interaction, with a large number of widespread risk factors being identified. With an intricate pathogenesis and symptomatology, it heavily impacts the quality of life and, due to the limited efficacy of traditional pharmacological agents, patients are likely to seek other medical and non-medical solutions to their problem. Over the last few years, significant research in this domain has emphasized the importance of various psychological therapies and nutritional recommendations. Nevertheless, a correlation has been established between functional dyspepsia and food intolerances, with more and more patients adopting different kinds of exclusion diets, leading to weight loss, restrictive eating behaviour and an imbalanced nutritional state, further negatively impacting their quality of life. Thus, in this systematic review, we aimed at analysing the impact and efficiency of certain exclusion diets undertook by patients, more precisely, the gluten-free diet and the low-FODMAP diet.

The Role of Leaky Gut in Functional Dyspepsia

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

Effectivity of treatment for children with functional dyspepsia

Functional dyspepsia is very common in children of all ages and has a significant impact on the patient’s family and quality of life. Since the revision of the Rome IV criteria with the introduction of two subtypes, the prevalence of functional dyspepsia has increased, but currently no guidelines for the treatment are available. The aim of this study was to characterize patients, who have been diagnosed with functional dyspepsia and analyze the outcome of different treatments they received. This is a retrospective study of pediatric patients, diagnosed with functional dyspepsia between March 2017 and September 2020. All patients aged between 0 and18 years, who complained about gastric symptoms, have had a normal full blood count, a normal thyroid function, a negative coeliac screening, and most importantly normal macro- and microscopic findings on esophago-gastro-duodenoscopy were included in the study. Patient’s data were extracted from the medical record and three months after the performance of the endoscopy, parents were interviewed about the effect of the treatment. A total of 154 patients (66.2% female, 33.8% male) between the age of 4 and 18 years were included. In 113 (73.4%) the leading symptom was epigastric pain, followed by nausea (22; 14.3%) and a fifth of the patients (females: 18.6%; males: 21.2%) self-reported a current stressor in clinic. After receiving the diagnosis of a functional nature, families chose following treatments: 50 STW5 (32.3%, overall, 10.4% added dietary changes, alternative treatment, and psychology support), psychological support (22.7%), alternative treatments (e.g., hypnotherapy, meditation; 19.5%), dietary changes (12.9%), lifestyle changes (9.7%), no treatment (11%) and in 10.4% no treatment was needed as symptoms resolved after endoscopy had been performed. Only lifestyle changes (p = 0.03) in females, dietary changes (p = 0.035 for girls, p = 0.06 for boys) and STW5 in males (p = 0.043) showed a statistically relevant correlation regarding duration of symptoms. There was no correlation between location of symptoms and effectiveness of treatment. It is recommended to treat patients from both subgroups of functional dyspepsia differently, in accordance with the currently available explanatory models of underlying pathophysiological processes. In this cohort of patients this could not be verified. As all patients did benefit from any treatment, it is likely that the treatment itself was not accountable for the relief of symptoms, but that most patients benefit from education on the diagnosis, reassurance and a recommendation of a healthy lifestyle. Some patients might benefit from medications, small changes in the diet, psychological support or alternative treatment, but success depends on individual, unpredictable factor.

[Rebamipide: evidence base for use in gastroenterology]

Rebamipide is a cytoprotective drug that has been used in practical gastroenterology for 30 years. This article summarizes the main results of the most relevant clinical studies of rebamipide in diseases of various parts of the gastrointestinal tract, including the esophagus, stomach, small and large intestine.

Evidence of Duodenal Epithelial Barrier Impairment and Increased Pyroptosis in Patients With Functional Dyspepsia on Confocal Laser Endomicroscopy and "Ex Vivo" Mucosa Analysis

INTRODUCTION

Duodenal epithelial barrier impairment and immune activation may play a role in the pathogenesis of functional dyspepsia (FD). This study was aimed to evaluate the duodenal epithelium of patients with FD and healthy individuals for detectable microscopic structural abnormalities.

METHODS

This is a prospective study using esophagogastroduodenoscopy enhanced with duodenal confocal laser endomicroscopy (CLE) and mucosal biopsies in patients with FD (n = 16) and healthy controls (n = 18). Blinded CLE images analysis evaluated the density of epithelial gaps (cell extrusion zones), a validated endoscopic measure of the intestinal barrier status. Analyses of the biopsied duodenal mucosa included standard histology, quantification of mucosal immune cells/cytokines, and immunohistochemistry for inflammatory epithelial cell death called pyroptosis. Transepithelial electrical resistance (TEER) was measured using Ussing chambers. Epithelial cell-to-cell adhesion proteins expression was assessed by real-time polymerase chain reaction.

RESULTS

Patients with FD had significantly higher epithelial gap density on CLE in the distal duodenum than that of controls (P = 0.002). These mucosal abnormalities corresponded to significant changes in the duodenal biopsy samples of patients with FD, compared with controls, including impaired mucosal integrity by TEER (P = 0.009) and increased number of epithelial cells undergoing pyroptosis (P = 0.04). Reduced TEER inversely correlated with the severity of certain dyspeptic symptoms. Furthermore, patients with FD demonstrated altered duodenal expression of claudin-1 and interleukin-6. No differences in standard histology were found between the groups.

DISCUSSION

This is the first report of duodenal CLE abnormalities in patients with FD, corroborated by biopsy findings of epithelial barrier impairment and increased cell death, implicating that duodenal barrier disruption is a pathogenesis factor in FD and introducing CLE a potential diagnostic biomarker in FD.

Diet and functional dyspepsia: Clinical correlates and therapeutic perspectives

Hypervigilance and symptoms anticipation, visceral hypersensitivity and gastroduodenal sensorimotor abnormalities account for the varied clinical presentation of functional dyspepsia (FD) patients. Many patients recognize meals as the main triggering factor; thus, dietary manipulations often represent the first-line management strategy in this cohort of patients. Nonetheless, scarce quality evidence has been produced regarding the relationship between specific foods and/or macronutrients and the onset of FD symptoms, resulting in non-standardized nutritional approaches. Most dietary advises are indeed empirical and often lead to exclusion diets, reinforcing in patients the perception of “being intolerant” to food and self-perpetuating some of the very mechanisms underlying dyspepsia physiopathology (i.e., hypervigilance and symptom anticipation). Clinicians are often uncertain regarding the contribution of specific foods to dyspepsia physiopathology and dedicated professionals (i.e., dietitians) are only available in tertiary referral settings. This in turn, can result in nutritionally unbalanced diets and could even encourage restrictive eating behaviors in severe dyspepsia. In this review, we aim at evaluating the relationship between dietary habits, macronutrients and specific foods in determining FD symptoms. We will provide an overview of the evidence-based nutritional approach that should be pursued in these patients, providing clinicians with a valuable tool in standardizing nutritional advises and discouraging patients from engaging into indiscriminate food exclusions.

Duodenal low-grade inflammation and expression of tight junction proteins in functional dyspepsia

BACKGROUND

Duodenal changes in functional dyspepsia (FD) might be related to the development of symptoms. However, relationships among low-grade inflammation, Helicobacter pylori infection, and protein expression by tight junctions (TJs) in the duodenum are unclear. We therefore aimed to determine whether duodenal inflammation and genes associated with TJ proteins are associated with FD.

METHODS

We evaluated inflammatory cell infiltration of the duodenum, H pylori infection, and genes associated with TJ proteins in duodenal biopsy specimens from 35 patients with FD according to the Rome III diagnostic questionnaire and from 31 asymptomatic controls without structural diseases. We immunohistochemically detected eosinophils and mast cells and counted them. The expression of claudins, occludin, and zonula occludens (ZO)-1 mRNA was evaluated using quantitative RT-PCR. Infection with H pylori was determined by measuring serum antibodies, rapid urease or urea breath tests, and endoscopic findings.

RESULTS

Sex, age, and H pyloriinfection rates did not differ between patients with FD and controls. The numbers of eosinophils and mast cells were significantly increased in patients with FD compared with controls and were significantly correlated. Inflammatory cell counts in the duodenum were not associated with H pylori infection status. Claudin-3 mRNA expression was increased in the patients with FD.

CONCLUSIONS

Subtle inflammation identified in the duodenum of patients with FD might be associated with the onset and persistence of dyspeptic symptoms.

Micro-inflammation in functional dyspepsia: A systematic review and meta-analysis

Functional dyspepsia (FD) is a gastrointestinal disorder of unknown etiology. Although micro-inflammation appears to be important in the pathogenesis, studies evaluating immune activation in FD have been inconsistent. A systematic review of literature and meta-analysis was performed to compare immunologic cell counts and cytokine levels in the mucosa and peripheral blood of individuals with FD and healthy controls. PubMed, Embase, and the Cochrane library were searched. Data on immunologic cell counts and cytokines levels among individuals with FD and control groups were extracted and compared by calculating standard mean differences (SMD). Thirty-seven studies met the inclusion criteria. Mast cell (SMD = 0.94, 95%CI 0.26-1.62, P = .007) and eosinophil counts (SMD = 0.36, 95%CI 0.06-0.68, P = .03) in the stomach were increased, among individuals with FD compared to controls. Similarly, mast cell (SMD = 0.66, 95%CI 0.20-1.13, P = 0.005) and eosinophil (SMD = 0.95, 95%CI 0.66-1.24; P < .001) counts in the duodenum were also increased in those with FD compared to controls. In a subgroup analysis, elevated eosinophil counts in the duodenum were observed in both post-prandial distress syndrome (SMD = 0.97, 95%CI 0.46-1.47, P = .0002) and epigastric pain syndrome subtypes (SMD = 1.16, 95%CI 0.48-1.83, P = .0008). No differences in mucosal intraepithelial lymphocyte, enterochromaffin cell, and neutrophil counts, as well as, peripheral interlukin-6 (IL-6) and IL-10 levels were observed among individuals with FD and controls. Micro-inflammation in the form of local immune cell infiltration, particularly eosinophils and mast cells, characterizes the pathogenesis of FD.