Targeted Dietary Exclusion Using Confocal Laser Endomicroscopy Does Not Improve Symptom Burden in Functional Dyspepsia: Results From a Randomized, Double‐Blind, Sham‐Controlled, Cross‐Over Study

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. 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. 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. 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.

Confocal Endomicroscopy Shows Food-Associated Changes in the Intestinal Mucosa of Patients With Irritable Bowel Syndrome

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BackgroundRecent reports have demonstrated that impaired barrier function and local microinflammation in the duodenal mucosa contribute to the pathogeneses of functional dyspepsia (FD). Thus, restoring normal barrier integrity becomes a potential therapeutic strategy in the treatment of FD. Sini-San (SNS) is a traditional Chinese prescription that exhibits therapeutic effects in FD, but the underlying mechanisms remain not well understood.MethodsFD rats were established by tail clamping method and the therapeutic effect of SNS was evaluated by measuring the visceral sensitivity and gastric compliance. Transepithelial electrical resistance (TEER) that reveals epithelial barrier integrity was measured by Ussing chamber. The expression of tight junction (TJ) proteins, occludin and claudin-1, in the duodenum was determined by Western blot and immunofluorescence. The amount of tumor necrosis factor alpha (TNF-α) and interferon gamma (INF-γ) in duodenal mucosa was detected by enzyme-linked immune sorbent assay (ELISA). The mRNA level of transient receptor potential vanilloid type 1 (TRPV1) was measured by quantitative real time-polymerase chain reaction (qPCR).ResultsSNS could improve gastric compliance and attenuate visceral hypersensitivity (VH) in FD rats. TEER was decreased in FD rats, but treatment with SNS restored normal level of TEER and the expression of occludin and claudin-1 in FD rats. In addition, SNS administration ameliorated FD-associated increase in the production of TNF-α, IFN-γ and the expression of TRPV1.ConclusionsThe therapeutic effect of SNS on FD is at least partially through improvement of TJ integrity and attenuation of FD-associated low-grade inflammation in the duodenum. Our findings highlight the molecular basis of SNS-based treatment of FD in human patients.

Confocal laser endomicroscopy (CLE) is a novel technique allowing real time invivo microscopy during standard endoscopy. Recently, acute mucosal alterations after food administration visualized by CLE have been linked to symptoms in irritable bowel syndrome (IBS). Interestingly, the observed reactions occurred in subjects without demonstrable allergic sensitization to food-this is in line with mechanistic research showing local but not systemic allergic sensitization to foods in an animal model for IBS. Here, European experts conducting CLE with food administration provide a narrative review of the available literature and propose practical guidance on the use of this technique. CLE allows physicians to observe acute mucosal reactions after the application of food to the duodenal mucosa in patients with functional gastrointestinal disorders. Some open-label interventions show a symptomatic benefit when patients exclude the nutrient that triggered an acute mucosal reaction. However, many technical, mechanistic, and clinical questions remain unanswered to date. Technically, the interobserver variability and learning curve requires systematic evaluation and criteria or cutoffs for alterations require validation. Mechanistic studies are needed to enhance our understanding of the mechanisms underlying observed alterations. Finally, rigorous blinded controlled studies are needed to assess a link of these observed alterations with symptom generation. CLE offers a platform allowing scientific insights related to food induced acute mucosal alterations. However, many questions remain unanswered, and more research is warranted to understand the role of acute mucosal alterations visualized upon food administration in IBS pathophysiology and treatment.

Confocal Laser Endomicroscopy: Technical Advances and Clinical Applications

Gastric metaplasia (GM) of the duodenum is difficult to assess because of its patchy distribution, and the role of GM in functional dyspepsia (FD) is not clear. The aims of this study were to determine if endomicroscopy could identify GM of the duodenum and whether GM has associations with FD. A series of 51 patients with FD and 25 asymptomatic controls were enrolled. Confocal laser endomicroscopy was performed to evaluate villi changes in vivo. Targeted biopsy specimens were then compared with histopathological results. The accuracy of the endomicroscopy diagnosis of GM during endoscopy was 92.8%, and the sensitivity, specificity, and positive and negative predictive values were 86.2%, 97.4%, 89.3%, and 96.6%, respectively. The mean κ-value for interobserver agreement was 0.89. GM in the duodenal bulb was more frequent in patients with FD than in the controls (33.3% vs 12%, P<0.05), especially in patients with epigastric pain syndrome (47.6% vs 12%, P<0.01). Endomicroscopy is useful for identifying GM, and GM might be related to FD. These findings could have potential applicability for duodenal screening, and suggest a possible targeting therapy in FD.

ObjectiveA considerable proportion of patients with irritable bowel syndrome (IBS) may be wheat-sensitive and respond to a gluten-free diet (GFD) although they do not have coeliac disease. However, a diagnostic...

We recently identified mucosal mast cell and eosinophil hyperplasia in association with a duodenal impaired barrier function in functional dyspepsia (FD). We aimed to further describe the implication of these immune cells by assessing their activation state at the ultrastructural level and by evaluating the association between impaired epithelial integrity and immune activation. Duodenal biopsies were obtained from 24 FD patients and 37 healthy controls. The ultrastructure of mast cells and eosinophils was analyzed by transmission electron microscopy. Transepithelial electrical resistance and paracellular permeability were measured to evaluate epithelial barrier function. The type of degranulation in eosinophils and mast cells was piecemeal. Eosinophils displayed higher degree of degranulation in FD patients than in controls (p < 0.0001). Quantification revealed a decreased granular density in eosinophils of FD patients (p < 0.0001). The degree of degranulation in mast cells was similar in both groups. However, a more heterogeneous profile was found in the FD group (p < 0.0001). No association between epithelial integrity and the number and activation state of mucosal eosinophils and mast cells was found. We demonstrated ultrastructural changes in degranulation state of eosinophils and mast cells, suggesting that eosinophil and mast cell activation play a role in the pathophysiology of FD.

Functional gastrointestinal disorders (FGIDs) are characterized by chronic complaints arising from disorganized brain-gut interactions leading to dysmotility and hypersensitivity. The two most prevalent FGIDs, affecting up to 16–26% of worldwide...

Functional dyspepsia (FD) is a complex disorder, in which multiple mechanisms underlie symptom generation, including impaired duodenal barrier function. Moreover, an altered duodenal bile salt pool was recently discovered in patients with FD. We aimed to evaluate the relationship between bile salts, bacterial translocation, and duodenal mucosal permeability in FD. Duodenal biopsies from patients with FD and healthy volunteers (HV) were mounted in Ussing chambers to measure mucosal resistance and bacterial passage in the absence and presence of fluorescein-conjugated Escherichia coli and glyco-ursodeoxycholic acid (GUDCA) exposure. In parallel, duodenal fluid aspirates were collected from patients and bile salts were analyzed. The transepithelial electrical resistance of duodenal biopsies from patients was lower compared with HV (21.4±1.3Ω.cm2 vs. 24.4±1.2Ω.cm2 ; P=.02; N=21). The ratio of glyco-cholic and glyco-chenodeoxycholic acid (GCDCA) to tauro- and GUDCA correlated positively with transepithelial electrical resistance in patients. Glyco-ursodeoxycholic acid slightly altered the mucosal resistance, resulting in similar values between patient and healthy biopsies (22.1±1.0Ω.cm2 vs. 23.0±1.0Ω.cm2 ; P=.5). Bacterial passage after 120minutes was lower for patient than for healthy biopsies (0.0 [0.0-681.8] vs. 1684.0 [0.0-4773.0] E coli units; P=.02). Glyco-ursodeoxycholic acid increased bacterial passage in patient biopsies (102.1 [0.0-733.0] vs. 638.9 [280.6-2124.0] E coli units; P=.009). No correlation was found between mucosal resistance and bacterial passage. Patients with FD displayed decreased duodenal mucosal resistance associated with bile salts, however, not associated with bacterial passage in vitro. In addition, the hydrophilic bile salt glyco-ursodeoxycholic acid abolished differences in mucosal resistance and bacterial passage between patient and control group.

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.

Irritable bowel syndrome (IBS) and functional dyspepsia (FD) are known to be among the most common digestive pathologies. In present paper, the literature data have been analyzed related to the study of intestinal permeability disorders as an etiopathogenetic factor in the development of functional gastrointestinal diseases. The intestinal mucosa is a barrier, performing many functions, and above all a protective function, which is to prevent the transition of intrinsic substances into the internal environment of the body. Recently, more and more scientific evidence has been accumulating that impaired permeability of the intestinal mucosa is an important factor in the development and progression of functional diseases of the gastrointestinal tract, in particular, IBS and FD. In these pathologies, the weakening of the barrier function of the intestinal mucosa is observed, which is the result of changes in the number of proteins of tight cell contacts, which affects the change in permeability, thus stimulating the transition of pathogenic factors from the intestinal lumen into the intestinal mucosa and causing activation of immunocompetent cells. In the pathogenesis of IBS the main place is given to the activation of mast cells in the mucosa of both small and large intestine, and in FD — to mast cells and eosinophils of the duodenal mucosa. Mast cells, which are cells of the immune system, in response to activation, produce certain inflammatory cytokines, the action of which is aimed at changing the sensitivity of nerve endings in the mucosa, causing the phenomenon of visceral hypersensitivity and changes in the tone and motor function of the gastrointestinal tract.Correction of the changes in intestinal permeability of the gastrointestinal mucosa at this stage of development of medical science is potentially one of the pathogenetic areas in the treatment of IBS and FD. Необходимо провести исследования эффективности препаратов, влияющих на функционирование кишечной стенки, относительно нормализации кишечной проницаемости при заболеваниях ЖКТ. Further researches are needed to study the efficacy of medications affecting the functions of intestinal wall, in regards intestinal permeability at gastrointestinal diseases.

Mo1565 – Confocal Laser Endomicroscopy in Patients with Functional Dyspepsia: Does “Leaky Gut” Play a Role?

Functional dyspepsia and the irritable bowel syndrome cause gastrointestinal symptoms in up to 15% of adults in most parts of the world. The term functional dyspepsia largely describes epigastric fullness, early satiety, epigastric pain or epigastric “burning”, while the term irritable bowel syndrome describes abdominal pain associated with changes in the frequency of defecation and the appearance of stools. The pathogenesis of symptoms appears to vary in different individuals but includes psychosocial distress, psychiatric disorders, genetic factors, visceral hypersensitivity, activation of mucosal immunity, altered gastrointestinal motility, dietary factors and changes in the intestinal microbiome and intestinal permeability. Although investigations to exclude non-functional disorders will be needed in many patients, the challenge is to emerge with a positive diagnosis of a functional disorder without extensive or repeated endoscopic or radiological procedures. Management is facilitated by an effective doctor-patient relationship and may include psychological assessment and counselling, stress-reduction techniques, exercise programmes and dietary advice such as the low-FODMAP diet. Medication will be needed in some patients but needs to be individualized because of wide variation in gastrointestinal symptoms and the presence or absence of significant psychiatric disorders.