Pathogenesis of irritable bowel syndrome: the mast cell connection

Functional Dyspepsia: Current Understanding and Future Perspective

BACKGROUND

Functional dyspepsia (FD) is a common disorder characterized by chronic or recurrent upper abdominal pain or discomfort without any structural abnormalities in the gastrointestinal tract. FD is categorized into two subgroups based on symptoms: postprandial distress syndrome (PDS) and epigastric pain syndrome.

SUMMARY

The pathophysiology of FD involves several mechanisms. Delayed gastric emptying is observed in approximately 30% of FD patients but does not correlate with symptom patterns or severity. Impaired gastric accommodation is important in the pathophysiology, particularly for PDS. Visceral hypersensitivity, characterized by heightened sensitivity to normal activities, contributes to the perception of discomfort or pain in FD. Alterations to the duodenal mucosa, including impaired mucosal barrier function and low-grade inflammation, are also implicated in the pathogenesis of FD. Microbial dysbiosis and psychological factors such as stress can further exacerbate symptoms. Treatment options include dietary modifications, establishing a physician-patient relationship, acid suppressants, prokinetics, neuromodulators, and behavioral therapies. Dietary recommendations include eating smaller, more frequent meals, and avoiding trigger foods. Acid suppressants are used as the first-line treatment. Prokinetics and neuromodulators aim to improve gastric motility and central pain processing, respectively. Behavioral therapies, including cognitive behavioral therapy and hypnotherapy, have shown benefits for refractory FD. Severe and refractory cases may require combination therapies or experimental treatments.

KEY MESSAGES

FD is a disorder of gut-brain interaction involving diverse pathophysiological mechanisms. Individualized treatment based on symptoms and responses to interventions is crucial. Further research is needed to improve the understanding of FD and advance the development of effective therapies.

Elderberry diet improves gut-brain axis dysfunction, neuroinflammation, and cognitive impairment in the rat model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is related to a problem in the gut-brain axis. This experimental research aimed to shed light on the potential therapeutic application of elderberry (EB), which can work on the axis and get better the IBS symptoms. There were three groups (36 Sprague-Dawley rats) in this experiment, including control, IBS, and IBS with EB diet (IBS + EB). Making use of intracolonic instillation of 1 ml of 4% acetic acid for 30 s, IBS was induced. 7 days later, the EB extract (2%) was added to the diets of all animals for 8 weeks. Some histological, behavioral, and stereological techniques were used to detect the effects of EB on the gut and brain tissues. The findings showed that the EB diet improved locomotion and decreased anxiety-like behavior in the rat models of IBS. Moreover, the diet dropped the expression of TNF-α and increased mucosal layer thickness and the number of goblet and mast cells in colon tissue samples. In the hippocampal samples, administration of EB prevented astrogliosis and astrocyte reactivity. Although hippocampal and cortical neurons decreased markedly in the IBS group, EB prevented the drop in the number of neurons. Although lots of research is needed to elucidate the effectiveness of EB in IBS and its exact molecular mechanism, the result of this study showed that EB as an antioxidant and immune-modulatory agent could be a promising research target to prevent the impairment in the gut-brain axis, and could ameliorative classic IBS symptoms.

Biomarkers in Interstitial Cystitis/Bladder Pain Syndrome with and without Hunner Lesion: A Review and Future Perspectives

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating urinary bladder condition that presents with a wide variety of clinical phenotypes. It is commonly characterized by persistent pelvic pain and lower urinary tract symptoms, such as urinary frequency and urgency. Current clinicopathological and genomic evidence has indicated that IC/BPS with Hunner lesions is a clinically relevant distinct subtype with proven bladder pathology of subepithelial chronic inflammatory changes that are characterized by enhanced local immune responses and epithelial denudation. However, other forms of IC/BPS lacking Hunner lesions are a symptom syndrome complex of non-inflammatory conditions with little evidence of bladder etiology, characterized by aberrant neural activity in neurotransmission systems which leads to central nervous sensitization with potential involvement of urothelial malfunction, or clinical presentation of somatic and/or psychological symptoms beyond the bladder. Given such distinct potential pathophysiology between IC/BPS subtypes, disease biomarkers of IC/BPS should be provided separately for subtypes with and without Hunner lesions. Tailored approaches that target characteristic immunological inflammatory processes and epithelial denudation for IC/BPS with Hunner lesions, or the sensitized/altered nervous system, urothelial malfunction, association with other functional somatic syndromes, and psychosocial problems for IC/BPS without Hunner lesions, are essential to identify optimal and reliable disease-specific IC/BPS biomarkers.

Mechanism of mast cell-mediated COX2-PGE2-Eps signaling pathway in visceral hypersensitivity in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder (FGID) whose pathophysiological mechanism is complex, involving genetic factors, psychosocial factors, low-grade mucosal inflammation, changes in the intestinal barrier, bacterial flora disorder, neuroimmune abnormalities, and high visceral sensitivity. In recent years, the mechanism of visceral hypersensitivity in IBS has become a hot research topic. Mast cells (MCs) are a group of immune cells that are distributed in the central nervous system and digestive system. The COX2-PGE2-Eps signaling pathway plays a major role in the visceral hypersensitivity in IBS, from peripheral sensitization to central sensitization, which provides a new idea for further clarifying the pathological mechanism of IBS.

Biology of heat stress; the nexus between intestinal hyperpermeability and swine reproduction

Unfavorable weather conditions are one of the largest constraints to maximizing farm animal productivity. Heat stress (HS), in particular, compromises almost every metric of profitability and this is especially apparent in the grow-finish and reproductive aspects of the swine industry. Suboptimal production during HS was traditionally thought to result from hypophagia. However, independent of inadequate nutrient consumption, HS affects a plethora of endocrine, physiological, metabolic, circulatory, and immunological variables. Whether these changes are homeorhetic strategies to survive the heat load or are pathological remains unclear, nor is it understood if they temporally occur by coincidence or if they are chronologically causal. However, mounting evidence suggest that the origin of the aforementioned changes lie at the gastrointestinal tract. Heat stress compromises intestinal barrier integrity, and increased appearance of luminal contents in circulation causes local and systemic inflammatory responses. The resulting immune activation is seemingly the epicenter to many, if not most of the negative consequences HS has on reproduction, growth, and lactation. Interestingly, thermoregulatory and production responses to HS are only marginally related. In other words, increased body temperature indices poorly predict decreases in productivity. Further, HS induced malnutrition is also a surprisingly inaccurate predictor of productivity. Thus, selecting animals with a "heat tolerant" phenotype based solely or separately on thermoregulatory capacity or production may not ultimately increase resilience. Describing the physiology and mechanisms that underpin how HS jeopardizes animal performance is critical for developing approaches to ameliorate current production issues and requisite for generating future strategies (genetic, managerial, nutritional, and pharmaceutical) aimed at optimizing animal well-being, and improving the sustainable production of high-quality protein for human consumption.

Interstitial cystitis/bladder pain syndrome: The evolving landscape, animal models and future perspectives

Interstitial cystitis/bladder pain syndrome is a debilitating condition of unknown etiology characterized by persistent pelvic pain with lower urinary tract symptoms and comprises a wide variety of potentially clinically useful phenotypes with different possible etiologies. Current clinicopathological and genomic evidence suggests that interstitial cystitis/bladder pain syndrome should be categorized by the presence or absence of Hunner lesions, rather than by clinical phenotyping based on symptomatology. The Hunner lesion subtype is a distinct inflammatory disease with proven bladder etiology characterized by epithelial denudation and enhanced immune responses frequently accompanied by clonal expansion of infiltrating B cells, with potential engagement of infection. Meanwhile, the non-Hunner lesion subtype is a non-inflammatory disorder with little evidence of bladder etiology. It is potentially associated with urothelial malfunction and neurophysiological dysfunction, and frequently presents with somatic and/or psychological symptoms, that commonly result in central nervous sensitization. Animal models of autoimmune cystitis and neurogenic sensitization might serve as disease models for the Hunner lesion and non-Hunner lesion subtypes, respectively. Here, we revisit the taxonomy of interstitial cystitis/bladder pain syndrome according to current research, and discuss its potential pathophysiology and representative animal models. Categorization of interstitial cystitis/bladder pain syndrome based on cystoscopy is mandatory to design optimized treatment and research strategies for each subtype. A tailored approach that specifically targets the characteristic inflammation and epithelial denudation for the Hunner lesion subtype, or the urothelial malfunction, sensitized/altered nervous system and psychosocial problems for the non-Hunner lesion subtype, is essential for better clinical management and research progress in this complex condition.

Network-Based Selection of Candidate Markers and Assays to Assess the Impact of Oral Immune Interventions on Gut Functions

To assess the safety and efficacy of oral immune interventions, it is important and required by regulation to assess the impact of those interventions not only on the immune system, but also on other organs such as the gut as the porte d'entrée. Despite clear indications that the immune system interacts with several physiological functions of the gut, it is still unknown which pathways and molecules are crucial to assessing the impact of nutritional immune interventions on gut functioning. Here we used a network-based systems biology approach to clarify the molecular relationships between immune system and gut functioning and to identify crucial biomarkers to assess effects on gut functions upon nutritional immune interventions. First, the different gut functionalities were categorized based on literature and EFSA guidance documents. Moreover, an overview of the current assays and methods to measure gut function was generated. Secondly, gut-function related biological processes and adverse events were selected and subsequently linked to the physiological functions of the GI tract. Thirdly, database terms and annotations from the Gene ontology database and the Comparative Toxicogenomics Database (CTD) related to the previously selected gut-function related processes were selected. Next, database terms and annotations were used to identify the pathways and genes involved in those gut functionalities. In parallel, information from CTD was used to identify immune disease related genes. The resulting lists of both gut and immune function genes showed an overlap of 753 genes out of 1,296 gut-function related genes indicating the close gut-immune relationship. Using bioinformatics enrichment tools DAVID and Panther, the identified gut-immune markers were predicted to be involved in motility, barrier function, the digestion and absorption of vitamins and fat, regulation of the digestive system and gastric acid, and protection from injurious or allergenic material. Concluding, here we provide a promising systems biology approach to identify genes that help to clarify the relationships between immune system and gut functioning, with the aim to identify candidate biomarkers to monitor nutritional immune intervention assays for safety and efficacy in the general population. This knowledge helps to optimize future study designs to predict effects of nutritional immune intervention on gut functionalities.

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.

Amelioration of Enterotoxigenic Escherichia coli-Induced Intestinal Barrier Disruption by Low-Molecular-Weight Chitosan in Weaned Pigs is Related to Suppressed Intestinal Inflammation and Apoptosis

Enterotoxigenic Escherichia coli (ETEC) infection destroys the intestinal barrier integrity, in turn, disrupting intestinal homoeostasis. Low-molecular-weight chitosan (LMWC) is a water-soluble chitosan derivative with versatile biological properties. Herein, we examined whether LMWC could relieve ETEC-induced intestinal barrier damage in weaned pigs. Twenty-four weaned pigs were allotted to three treatments: (1) non-infected control; (2) ETEC-infected control; and (3) ETEC infection + LMWC supplementation (100 mg/kg). On day 12, pigs in the infected groups were administered 100 mL of ETEC at 2.6 × 10⁹ colony-forming units/mL to induce intestinal barrier injury. Three days later, serum samples were obtained from all pigs, which were then slaughtered to collect intestinal samples. We evidenced that LMWC not only increased (P < 0.05) the occludin protein abundance but also decreased (P < 0.05) the interleukin-6, tumour necrosis factor-α and mast cell tryptase contents, and the apoptotic epithelial cell percentages, in the small intestine of ETEC-infected pigs. Furthermore, LMWC down-regulated (P < 0.05) the small intestinal expression levels of critical inflammatory- and apoptotic-related genes, such as Toll-like receptor 4 (TLR4) and tumour necrosis factor receptor 1 (TNFR1), as well as the intra-nuclear nuclear factor-κB (NF-κB) p65 protein abundance, in the ETEC-infected pigs. Our study indicated a protective effect of LMWC on ETEC-triggered intestinal barrier disruption in weaned pigs, which involves the repression of intestinal inflammatory responses via blocking the TLR4/NF-κB signalling pathway and the depression of epithelial cell death via TNFR1-dependent apoptosis.

Eosinophilic gastroenteritis: diagnosis and clinical perspectives

Eosinophilic gastroenteritis (EGE) is a digestive disorder in children and adults that is characterized by eosinophilic infiltration in the stomach and intestine. The underlying molecular mechanisms predisposing to this disease are unknown, but it seems that hypersensitivity response plays a major role in its pathogenesis, as many patients have a history of seasonal allergies, food sensitivities, asthma, and eczema. Symptoms and clinical presentations vary, depending on the site and layer of the gastrointestinal wall infiltrated by eosinophils. Laboratory results, radiological findings, and endoscopy can provide important diagnostic evidence for EGE; however, the cornerstone of the diagnosis remains the histological examination of gastric and duodenal specimens for evidence of eosinophilic infiltration (>20 eosinophils per high-power field), and finally clinicians make the diagnosis in correlation with and by exclusion of other disorders associated with eosinophilic infiltration. Although spontaneous remission is reported in around 30%–40% of EGE cases, most patients require ongoing treatment. The management options for this disorder include both dietary and pharmacological approaches, with corticosteroids being the mainstay of therapy and highly effective. The subsequent course is quite variable. Some patients have no recurrences, while a few experience recurrent symptoms during or immediately after corticosteroid interruption. An alternative therapeutic armamentarium includes mast-cell stabilizers, leukotriene antagonists, antihistamines, immunomodulators, and biological agents. In this review, we provide a summary of the different diagnostic tools utilized in practice, as well as the different therapeutic approaches available for EGE management.

Sustained pain hypersensitivity in the stressed colon: Role of mast cell-derived nerve growth factor-mediated enteric synaptic plasticity

BACKGROUND

Sustained pain hypersensitivity is the hallmark of stressed colon which could be partially explained by central sensitization with synaptic plasticity, the key mechanism of memory. We previously identified that synaptic plasticity of enteric nerve system (ENS) contributed to peripheral pain maintaining in the gut. However, the mechanisms of enteric "memory" formation remain elusive.

METHODS

In this study, rats were exposed to water avoidance stress (WAS) or sham stress (SS), with cromolyn sodium or physiological saline injected intraperitoneally 30 minutes before stress every day. The abdominal withdrawal reflex scores, mesenteric afferent nerve activity, enteric neural c-fos expression, and enteric synaptic plasticity were assessed, and mast cell infiltration and degranulation. Furthermore, colonic mucosal mediators-induced enteric synaptic plasticity and the role of mast cell-derived nerve growth factor (NGF), tryptase, and histamine were investigated via ex vivo longitudinal muscle-myenteric plexus (LMMP) organotypic culture.

KEY RESULTS

It is shown that mast cell stabilizing inhibited WAS-induced visceral hypersensitivity through enhancing visceral pain threshold, decreasing spontaneous and distention-induced mesenteric afferent firing, and downregulating enteric neural activation (c-fos). Importantly, WAS led to evident enteric synaptic plasticity, but decreased by cromolyn. Water avoidance stress-derived mucosal supernatants markedly enhanced the c-fos expression and enteric synaptic plasticity in LMMP tissues, which could be eliminated by mast cell inhibition or NGF neutralization, but not tryptase or histamine blocking.

CONCLUSIONS & INFERENCES

In conclusion, mast cells/NGF pathway may be the key regulator of synaptic plasticity of ENS and participate in the formation of chronic stress-induced sustained visceral hypersensitivity.

Chlorogenic acid improves intestinal barrier functions by suppressing mucosa inflammation and improving antioxidant capacity in weaned pigs

Intestinal barrier plays key roles in maintaining intestinal homeostasis. Inflammation and oxidative damage can severely destroy the intestinal integrity of mammals. Chlorogenic acid (CGA) is a natural polyphenol present in human diet and plants, possessing potent antioxidant and anti-inflammatory activities. This study was conducted to investigate the protective effects of CGA and its molecular mechanisms on intestinal barrier function in a porcine model. Twenty-four weaned pigs were allotted to two groups and fed with a basal diet or a basal diet containing 1000 mg/kg CGA. The results showed that CGA decreased serum D-lactate and diamine oxidase levels, and enhanced the expression and localization of claudin-1 protein in apical intercellular region of small intestinal epithelium. Interestingly, CGA significantly decreased the mucosa histamine and tryptase contents, as well as the tryptase-positive mast cell counts. Moreover, the expression levels of critical inflammation molecules (interleukin-1β, interleukin-6, tumor necrosis factor-α, and nuclear factor-κB) were down-regulated by CGA in jejunal and ileal mucosa. However, the expression levels of inflammation repressors (suppressor of cytokine signaling 1 and toll-interacting protein) were up-regulated by CGA. Importantly, CGA decreased the malondialdehyde content but elevated glutathione peroxidase and catalase content in duodenal and jejunal mucosa. The expression levels of critical molecules in antioxidant signaling (nuclear factor erythroid-derived 2-related factor 2 and heme oxygenase-1) were elevated by CGA in duodenal and jejunal mucosa. These results suggested that CGA could ameliorate intestinal barrier disruption in weaned pigs, which might be mediated by suppressing the TLR4/NF-κB signaling pathway and activating the Nrf2/HO-1 signaling pathway.

Increased intestinal mucosal leptin levels in patients with diarrhea-predominant irritable bowel syndrome

AIM

To measure the leptin levels in patients with diarrhea-predominant irritable bowel syndrome (IBS-D) and analyze the relationship of leptin with clinical features, visceral sensitivity, mast cells, and nerve fibers.

METHODS

Forty-two patients with IBS-D fulfilling the Rome III criteria and 20 age- and sex-matched healthy controls underwent clinical and psychological evaluations using validated questionnaires (including IBS Symptom Severity Scale, IBS-specific Quality of Life, Hamilton Anxiety Scale, and Hamilton Depression Scale), along with colonoscopy, colonic mucosal biopsy, and visceral sensitivity testing. Serum leptin levels were assayed using enzyme-linked immunosorbent assay. Mucosal leptin expression and localization were evaluated using immunohistochemistry and immunofluorescence. Mucosal leptin mRNA levels were quantified using quantitative real-time reverse transcription polymerase chain reaction. Mast cell counts and activation rates were investigated by toluidine blue staining. Correlation analyses between these parameters were performed.

RESULTS

There were no statistically significant differences in age, gender, or body mass index between the IBS-D group and the control group. The median IBS Symptom Severity Scale score in the IBS-D group was 225.0 (range, 100-475). IBS-D patients had significantly increased anxiety [IBS-D: median, 6.5; interquartile range (IQR), 3.3; control: median, 2.0; IQR, 2.0; P < 0.001] and depression (IBS-D: median, 7.0; IQR, 3.0; control: median, 3.0; IQR, 2.0; P < 0.001) scores. IBS-D patients had significantly lower first sensation threshold (IBS-D: median, 50.6; IQR, 25.9; control: median, 80.5; IQR, 18.6; P < 0.001), defecation sensation threshold (IBS-D: median, 91.5; IQR, 29.3; control: median, 155.0; IQR, 21.1; P < 0.001) and maximum tolerable threshold (IBS-D: median, 163.2; IQR, 71.2; control: median, 226.2; IQR, 39.3; P < 0.001). Mucosal leptin expression, as reflected by integrated optical density (IBS-D: median, 4424.71; IQR, 4533.63; control: median, 933.65; IQR, 888.10; P < 0.001), leptin mRNA expression (IBS-D: median, 1.1226; IQR, 1.6351; control: median, 0.8947; IQR, 0.4595; P = 0.009), and mast cell activation rate (IBS-D: median, 71.2%; IQR, 12.9%; control group: median, 59.4%; IQR, 18.88%; P < 0.001) were significantly increased in IBS-D patients. The colocalization of leptin and leptin receptors was observed on mast cells and PGP9.5-positive nerve fibers in the intestinal mucosa. Also, leptin expression was positively correlated with anxiety, depression, and the mast cell activation rate, but negatively correlated with the defecation sensation threshold and the maximum tolerance threshold during visceral sensitivity testing (adjusted P < 0.0038).

CONCLUSION

Increased levels of mucosal leptin may interact with mast cells and the nervous system to contribute to the pathogenesis of IBS-D.

Role of mast cell activation and degranulation in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder whose treatment is unsatisfactory as its pathophysiology is multifactorial. The factors involved in IBS pathophysiology include visceral hypersensitivity, intestinal dysmotility, psychological factors, dysregulated gut-brain axis, intestinal microbiota alterations, impaired intestinal permeability, and mucosal immune alterations. Recently, mucosal immune alterations have received much attention in IBS. Mast cells are abundant in the intestine, and they communicate with adjacent cells such as epithelial, neuronal, smooth muscle cells or other immune cells through the mediators released when they are activated. Many studies have suggested that mast cells play a role in the pathophysiology of IBS. This review will focus on the role of mast cells in IBS.

Transgenerational transmission of systemic mast cell activation disease-genetic and epigenetic features

Systemic mast cell activation disease (MCAD) comprises disorders characterized by an enhanced release of mast cell mediators accompanied by a varying accumulation of dysfunctional mast cells. Within the last years, evidence has been presented that MCAD is a multifactorial polygenic determined disease with the KIT(D816V) mutation and its induced functional consequences considered as special case. The respective genes encode proteins for various signaling pathways, epigenetic regulators, the RNA splicing machinery, and transcription factors. Transgenerational transmission of MCAD appears to be quite common. The basics of the molecular mechanisms underlying predisposition of the disease, that is, somatic and germline mutations and the contribution of epigenetic processes have become identifiable. The aim of the present review is to present and discuss available genetic, epigenetic and epidemiological findings, and to present a model of MCAD pathogenesis.

Chronic intractable diarrhea caused by gastrointestinal mastocytosis

As mast cells have been highlighted in the pathogenesis of diarrhea-predominant irritable bowel syndrome, a new term "mastocytic enterocolitis" was suggested by Jakate and colleagues to describe an increase in mucosal mast cells in patients with chronic intractable diarrhea and favorable response to treatment with antihistamines. Although it is not an established disease entity, two cases have been reported in the English medical literature. Here, for the first time in Asia, we report another case of chronic intractable diarrhea caused by gastrointestinal mastocytosis. The patient was a 70-year-old male with chronic intractable diarrhea for 3 months; the cause of the diarrhea remained obscure even after exhaustive evaluation. However, biopsy specimens from the jejunum were found to have increased mast cell infiltration, and the patient was successfully treated with antihistamines.

Fish oil enhances intestinal barrier function and inhibits corticotropin-releasing hormone/corticotropin-releasing hormone receptor 1 signalling pathway in weaned pigs after lipopolysaccharide challenge

Stress induces injury in intestinal barrier function in piglets. Long-chain n-3 PUFA have been shown to exhibit potential immunomodulatory and barrier protective effects in animal models and clinical trials. In addition, corticotropin-releasing hormone (CRH)/CRH receptor (CRHR) signalling pathways play an important role in stress-induced alterations of intestinal barrier function. We hypothesised that fish oil could affect intestinal barrier function and CRH/CRHR signalling pathways. In total, thirty-two weaned pigs were allocated to one of four treatments. The experiment consisted of a 2×2 factorial design, and the main factors included immunological challenge (saline or lipopolysaccharide (LPS)) and diet (5 % maize oil or 5 % fish oil). On d 19 of the trial, piglets were treated with saline or LPS. At 4 h after injection, all pigs were killed, and the mesenteric lymph nodes (MLN), liver, spleen and intestinal samples were collected. Fish oil decreased bacterial translocation incidence and the number of translocated micro-organisms in the MLN. Fish oil increased intestinal claudin-1 protein relative concentration and villus height, as well as improved the intestinal morphology. In addition, fish oil supplementation increased intestinal intraepithelial lymphocyte number and prevented elevations in intestinal mast cell and neutrophil numbers induced by LPS challenge. Moreover, fish oil tended to decrease the mRNA expression of intestinal CRHR1, CRH and glucocorticoid receptors. These results suggest that fish oil supplementation improves intestinal barrier function and inhibits CRH/CRHR1 signalling pathway and mast cell tissue density.

Mast Cells and Irritable Bowel Syndrome: From the Bench to the Bedside

Irritable bowel syndrome (IBS) is traditionally defined as a functional disorder since it lacks demonstrable pathological abnormalities. However, in recent years, low grade inflammatory infiltration, often rich in mast cells, in both the small and large bowel, has been observed in some patients with IBS. The close association of mast cells with major intestinal functions, such as epithelial secretion and permeability, neuroimmune interactions, visceral sensation, and peristalsis, makes researchers and gastroenterologists to focus attention on the key roles of mast cells in the pathogenesis of IBS. Numerous studies have been carried out to identify the mechanisms in the development, infiltration, activation, and degranulation of intestinal mast cells, as well as the actions of mast cells in the processes of mucosal barrier disruption, mucosal immune dysregulation, visceral hypersensitivity, dysmotility, and local and central stress in IBS. Moreover, therapies targeting mast cells, such as mast cell stabilizers (cromoglycate and ketotifen) and antagonists of histamine and serotonin receptors, have been tried in IBS patients, and have partially exhibited considerable efficacy. This review focuses on recent advances in the role of mast cells in IBS, with particular emphasis on bridging experimental data with clinical therapeutics for IBS patients.

The role of mast cells in functional GI disorders

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 population, are functional dyspepsia and irritable bowel syndrome. Their etiopathogenic mechanisms remain unclear, however, recent observations reveal low-grade mucosal inflammation and immune activation, in association with impaired epithelial barrier function and aberrant neuronal sensitivity. These findings come to challenge the traditional view of FGIDs as pure functional disorders, and relate the origin to a tangible organic substrate. The mucosal inflammatory infiltrate is dominated by mast cells, eosinophils and intraepithelial lymphocytes in the intestine of FGIDs. It is well established that mast cell activation can generate epithelial and neuro-muscular dysfunction and promote visceral hypersensitivity and altered motility patterns in FGIDs, postoperative ileus, food allergy and inflammatory bowel disease. This review will discuss the role of mucosal mast cells in the gastrointestinal tract with a specific focus on recent advances in disease mechanisms and clinical management in irritable bowel syndrome and functional dyspepsia.

Molecular and cellular mechanisms of tight junction dysfunction in the irritable bowel syndrome

The pathophysiological mechanisms of the irritable bowel syndrome (IBS), one of the most prevalent gastrointestinal disorders, are complex and have not been fully elucidated. The present study aimed to investigate the molecular and cellular mechanisms of tight junction (TJ) dysfunction in IBS. Intestinal tissues of IBS and non‑IBS patients were examined to observe cellular changes by cell chemical tracer electron microscopy and transmission electron microscopy, and intestinal claudin‑1 protein was detected by immunohistochemistry, western blot analysis and fluorescence quantitative polymerase chain reaction. Compared with the control group, TJ broadening and the tracer extravasation phenomenon were observed in the diarrhea‑predominant IBS group, and a greater number of neuroendocrine cells and mast cells filled with high‑density particles in the endocrine package pulp as well as a certain extent of vacuolization were present. The expression of claudin‑1 in diarrhea‑predominant IBS patients was decreased, while it was increased in constipation‑predominant IBS patients. In conclusion, the results of the present study indicated that changes in cellular structure and claudin‑1 levels were associated with Tjs in IBS.

Quantitative evaluation of duodenal eosinophils and mast cells in adult patients with functional dyspepsia

The role of duodenal eosinophils and mast cells (MCs) in the pathogenesis of functional dyspepsia (FD) remains poorly understood. This study aimed to examine the counts and degranulation of duodenal eosinophils and MCs in FD patients to explore the association between FD and both cell types. We recruited 141 FD patients and 39 healthy controls for this study. Biopsy specimens were collected from the duodenal bulb (D1) and the descending part (D2) of the duodenum of all participants. Eosinophil counts and degranulation, and MC counts and degranulation at both sites were quantitatively evaluated by hematoxylin and eosin staining, major basic protein immunostaining, and toluidine blue staining, respectively. Receiver operating characteristic analysis was applied to evaluate the diagnostic accuracy of these parameters in identifying FD cases. We found that the eosinophil counts at D2 were considerably increased in FD patients compared with healthy controls, and that the proportion of cases with eosinophil degranulation at D2 was significantly higher in the FD group. In addition, FD patients showed significantly increased MC counts and degranulation both at D1 and D2, and receiver operating characteristic analysis further demonstrated that these parameters, in particular the degranulation of MCs, appear to be highly sensitive and specific for the identification of FD patients. Our findings suggest that the increased eosinophil counts and degranulation at D2, and the increased MC counts and degranulation at D1 and D2 may be the histologic markers of FD. MC degranulation at D1 and D2 appears to be highly sensitive and specific for FD identification.

Intestinal barrier function and the brain-gut axis

The luminal-mucosal interface of the intestinal tract is the first relevant location where microorganism-derived antigens and all other potentially immunogenic particles face the scrutiny of the powerful mammalian immune system. Upon regular functioning conditions, the intestinal barrier is able to effectively prevent most environmental and external antigens to interact openly with the numerous and versatile elements that compose the mucosal-associated immune system. This evolutionary super system is capable of processing an astonishing amount of antigens and non-immunogenic particles, approximately 100 tons in one individual lifetime, only considering food-derived components. Most important, to develop oral tolerance and proper active immune responses needed to prevent disease and inflammation, this giant immunogenic load has to be managed in a way that physiological inflammatory balance is constantly preserved. Adequate functioning of the intestinal barrier involves local and distant regulatory networks integrating the so-called brain-gut axis. Along this complex axis both brain and gut structures participate in the processing and execution of response signals to external and internal changes coming from the digestive tract, using multidirectional pathways to communicate. Dysfunction of brain-gut axis facilitates malfunctioning of the intestinal barrier, and vice versa, increasing the risk of uncontrolled immunological reactions that may trigger mucosal and brain low-grade inflammation, a putative first step to the initiation of more permanent gut disorders. In this chapter, we describe the structure, function and interactions of intestinal barrier, microbiota and brain-gut axis in both healthy and pathological conditions.

Intestinal allergic inflammation in birch pollen allergic patients in relation to pollen season, IgE sensitization profile and gastrointestinal symptoms

BACKGROUND

Birch pollen allergic patients frequently experience gastrointestinal upset accompanied by a local allergic inflammation in the small intestine especially during the pollen season. However, it is not known if the GI pathology is connected to the subjective symptoms of the patient. The objective of this study was to evaluate the immune pathology of the duodenal mucosa and the serum IgE antibody profiles in birch pollen allergic patients in relation to their gastrointestinal symptoms, during and outside the birch pollen season.

METHODS

Thirty-two patients with birch pollen allergy and sixteen healthy controls were enrolled in the study. Twenty allergic patients had gastrointestinal symptoms and twelve did not. All participants underwent an allergy investigation and gastroscopy with duodenal biopsy. The duodenal biopsies were retrieved during the pollen season (May-June) and off-season (November-March). The biopsies were immunostained for mast cells (IgE and tryptase), eosinophils, T cells (CD3), and dendritic cells (CD11c). Pollen-specific IgE antibodies were determined by ImmunoCAP and component microarray (ISAC).

RESULTS

Patients in both pollen allergic groups showed similar degree of intestinal allergic inflammation during the pollen season regardless of gastrointestinal symptoms. The eosinophils, mast cells and dendritic cells were increased in the mucosa. Patients with gastrointestinal symptoms had significantly elevated IgE antibodies to birch (rBet v 1), hazelnut (rCor a 1), and apple (rMal d1) during the pollen season.

CONCLUSIONS

Patients allergic to birch pollen have clear signs of an ongoing allergic inflammation in their intestinal mucosa, which is aggravated during the pollen season. The magnitude of the allergic intestinal inflammation is not associated with subjective gastrointestinal symptoms of the individual patient.

Tight junctions and IBS--the link between epithelial permeability, low-grade inflammation, and symptom generation?

In this issue of Neurogastroenterology and Motility, Dr Ewa Wilcz-Villega and colleagues report low expression of E-cadherin, a tight junction protein involved in the regulation of paracellular permeability, in the colonic mucosa of patients with the irritable bowel syndrome (IBS) with predominance of diarrhea (IBS-D) or alternating symptoms (IBS-A). These findings constitute an improvement in our knowledge of epithelial barrier disruption associated with IBS. There is mounting evidence to indicate that a compromised epithelial barrier is associated with low-grade immune activation and intestinal dysfunction in at least a proportion of IBS patients. During the last 10 years of research, much interest has focused on the increase in the number of different types of immune cells in the gut mucosa of IBS patients including: mast cells, T lymphocytes, and other local cells such as enteroendocrine cells. The inflammatory mediators released by these cells or other luminal factors could be at the origin of altered epithelial barrier functions and enteric nervous system signaling, which lead to gut hypersensitivity. A current conceptual framework states that clinical symptoms of IBS could be associated with structural and functional abnormalities of the mucosal barrier, highlighting the crucial importance of elucidating the contributory role of epithelial barrier defects in the pathogenesis of IBS. More importantly, disruption of the epithelial barrier could also participate in the generation of persistent abdominal pain and discomfort mimicking IBS in patients with inflammatory bowel diseases considered in remission. This mini review gives a brief summary of clinical and experimental evidence concerning the mechanisms underlying epithelial barrier defects in IBS.

Mast cell number, substance P and vasoactive intestinal peptide in irritable bowel syndrome with diarrhea

BACKGROUND

Recent studies have shown that mast cells play an important role in irritable bowel syndrome (IBS). We investigated the relationship between mast cells and the gut hormones substance P and vasoactive intestinal peptide (VIP) in irritable bowel syndrome with diarrhea (IBS-D).

METHODS

Colonoscopic biopsies were performed on the rectal mucosa of 43 subjects (IBS-D patients: 22, healthy volunteers: 21) diagnosed according to the Rome III criteria. Mast cells, and substance P & VIP were evaluated by quantitative immunohistology and image analysis. Mast cells were counted as tryptase-positive cells in the lamina propria, and substance P and VIP levels were expressed as percentages of total areas of staining.

RESULTS

Mast cell counts were higher in IBS-D patients than healthy volunteers (9.6 ± 3.3 vs. 5.7 ± 2.5/high power field (HPF), p < 0.01). Substance P was also elevated (0.11 ± 0.08% vs. 0.03 ± 0.02 %, p < 0.01) while VIP was only high in women with IBS-D. Mast cell counts were positively correlated with levels of substance P & VIP in women but not men (women: r = 0.625, p < 0.01 for substance P and r = 0.651, p < 0.01 for VIP). However, mast cell counts were not correlated with IBS symptoms including abdominal pain.

CONCLUSION

Mast cells are activated leading to the raised levels of substance P & VIP in IBS-D patients. However, the correlation between mast cells and levels of substance P & VIP differs according to gender.

Correlation between serum serotonin and endoscopy inflammation scores in patients with ileal pouches

BACKGROUND

Inflammatory and functional complications are common in patients with inflammatory bowel disease (IBD) after restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA). The pathogenesis of these complications remains poorly understood, and there is discrepancy between the clinical symptoms and objective endoscopic inflammation scores in these patients. While serum serotonin level has been reported to be associated with symptoms of irritable bowel syndrome, its association with ileal pouch disorders has not been studied.

AIM

To investigate the association between serum serotonin level and symptoms and endoscopic inflammation in patients with IPAA.

METHODS

A total of 185 consecutive eligible IPAA patients who presented to a specialized Pouchitis Clinic from Jan 2009 to May 2009 were prospectively recruited. Patients were divided into 4 groups: normal pouch, irritable pouch syndrome (IPS), inflammatory pouch disorders (Crohn's disease, acute and chronic pouchitis, and cuffitis), and surgical complications. Serum serotonin level was measured and analyzed for correlation with clinical and endoscopic inflammation scores.

RESULTS

Demographic and clinical variables were evaluated, including age, gender, smoking history, duration of UC, duration of the pouch, and disease category of the pouch. The median fasting serum serotonin level was comparable among the 4 groups: 94.0 ng/ml (interquartile range [IQR], 70.0, 128.1), 89.2 ng/ml (IQR 54.2, 155.9), 90.3 ng/ml (IQR 49.7, 164.1), 77.9 ng/ml (IQR 54.7, 129.0), for normal pouch, irritable pouch, inflammatory pouch disorders, and surgical complication groups, respectively (p=0.91). A significant association between serum serotonin level and the Pouchitis Disease Activity Index (PDAI) endoscopy subscore of the pouch (odds ratio [OR]=1.9, 95% confidence interval [CI]: 1.2, 2.9, p<0.05) and total PDAI endoscopy score (OR=1.8; 95% CI: 1.2, 2.8, p<0.05) in the inflammatory complication group were noted.

CONCLUSIONS

Serum serotonin level appears to correlate with the PDAI endoscopy subscores and total PDAI score in patients with inflammatory complications suggesting that the hormone may be involved in mechanisms of mucosal inflammation. These findings may promote future treatment strategies for patients with pouch inflammation.

Cellular and molecular basis of intestinal barrier dysfunction in the irritable bowel syndrome

The etiopathogenesis of the irritable bowel syndrome (IBS), one of the most prevalent gastrointestinal disorders, is not well known. The most accepted hypothesis is that IBS is the result of the disturbance of the 'brain-gut axis.' Although the pathophysiological mechanisms of intestinal dysfunction are complex and not completely understood, stress, infections, gut flora, and altered immune response are thought to play a role in IBS development. The intestinal barrier, composed of a single-cell layer, forms a physical barrier that separates the intestinal lumen from the internal milieu. The loss of integrity of this barrier is related with mucosal immune activation and intestinal dysfunction in IBS. The number of mast cells and T lymphocytes is increased in the intestinal mucosa of certain IBS patients, and the mediators released by these cells could compromise the epithelial barrier function and alter nerve signaling within the enteric nervous system. The association of clinical symptoms to structural and functional abnormalities of the mucosal barrier in IBS patients highlights the importance of understanding the physiological role of the gut barrier in the pathogenesis of this disorder. This review summarizes the clinical and experimental evidences indicating the cellular and molecular mechanisms of IBS symptomatology, and its relevance for future translational research.

Need for a comprehensive medical approach to the neuro-immuno-gastroenterology of irritable bowel syndrome

Irritable bowel syndrome (IBS) is defined by the Rome III criteria as symptoms of recurrent abdominal pain or discomfort with the onset of a marked change in bowel habits with no evidence of an inflammatory, anatomic, metabolic, or neoplastic process. As such, many clinicians regard IBS as a central nervous system problem of altered pain perception. Here, we review the recent literature and discuss the evidence that supports an organic based model, which views IBS as a complex, heterogeneous, inter-dependent, and multi-variable inflammatory process along the neuronal-gut axis. We delineate the organic pathophysiology of IBS, demonstrate the role of inflammation in IBS, review the possible differences between adult and pediatric IBS, discuss the merits of a comprehensive treatment model as taught by the Institute of Functional Medicine, and describe the potential for future research for this syndrome.

Irritable pouch syndrome is characterized by visceral hypersensitivity

BACKGROUND

Irritable pouch syndrome (IPS) is a functional disorder in patients with ileal pouch-anal anastomosis (IPAA), which presents with symptoms in the absence of structural abnormalities of the pouch. Thus, it resembles other functional disorders, such as irritable bowel syndrome characterized by visceral hypersensitivity in the presence of normal rectal biomechanics. The aim was to assess pouch biomechanics and perception of balloon distension in different groups of subjects with IPAA and to correlate the findings with clinical features.

METHODS

Pouch tone, compliance, and sensation to balloon distension were measured in 18 patients with IPS, 11 patients with active pouch inflammation (pouchitis or Crohn's disease of the pouch), and 12 asymptomatic subjects with normal pouches. All patients were recruited from a subspecialty Pouchitis Clinic.

RESULTS

Scores of sensation of gas, urge to defecate, and pain measured by visual analog scales at various distension pressures were significantly higher in IPS than pouchitis and normal pouch patients. Pouch tone was comparable among the groups and compliance was reduced in the pouchitis group. The visual analog scale showed a trend of correlation with the Pouchitis Disease Activity Index symptom scores in IPS.

CONCLUSIONS

IPS, like other gut functional disorders, is characterized by visceral hypersensitivity, with normal pouch biomechanics.

The brain-gut axis in abdominal pain syndromes

The importance of bidirectional brain-gut interactions in gastrointestinal (GI) illness is increasingly recognized, most prominently in the area of functional GI syndromes such as irritable bowel syndrome (IBS), functional dyspepsia, and functional chest pain. The brain receives a constant stream of interoceptive input from the GI tract, integrates this information with other interoceptive information from the body and with contextual information from the environment, and sends an integrated response back to various target cells within the GI tract. This system is optimized to assure homeostasis of the GI tract during physiological perturbations and to adapt GI function to the overall state of the organism. In health, the great majority of interoceptive information reaching the brain is not consciously perceived but serves primarily as input to autonomic reflex pathways. In patients with functional abdominal pain syndromes, conscious perception of interoceptive information from the GI tract, or recall of interoceptive memories of such input, can occur in the form of constant or recurrent discomfort or pain. This is often associated with alterations in autonomic nervous system output and with emotional changes. A model is proposed that incorporates reported peripheral and central abnormalities in patients with IBS, extrapolates similar alterations in brain-gut interactions to patients with other chronic abdominal pain syndromes, and provides novel treatment targets.

[Systemic mastocytosis--definition of an internal disease]

Systemic mastocytosis comprises disorders characterized by an accumulation of genetically altered mast cells in all organs and tissues due to an increased proliferation rate and reduced apoptosis of those pathologic mast cells. Release of their mediators can effectively influence organ function and can lead to systemic effects without inducing traces in routinely used laboratory parameters or imaging methods. In most cases, little invasive investigations allow diagnosing the disease and, hence, an appropriate therapy consisting of a basic medication with antihistamine and mast cell membrane-stabilizing compounds that should be supplemented, if required, by a medication adapted to individual symptoms, can be initiated. Because of the probably high prevalence of the disorder, systemic mastocytosis should be considered as a differential diagnosis in particular in the case of chronic gastrointestinal complaints such as abdominal pain/discomfort possibly associated with diarrhea, at an early stage.

Migration of eosinophils and CCR2-/CD68-double positive cells into the duodenal mucosa of patients with postinfectious functional dyspepsia

OBJECTIVES

Recent studies have shown that postinfectious functional dyspepsia (FD) symptoms may persist after elimination of gastrointestinal (GI) infection as well as postinfectious irritable bowel syndrome accompanying colonic inflammation. However, it is unclear whether intestinal chronic inflammation can contribute to clinical symptoms of certain FD patients such as postinfectious FD. To determine the relationship between local inflammation of the duodenum and clinical symptoms, we evaluated the infiltration of several phenotypes of duodenal inflammatory cells as well as gastric motility using (13)C urea breath test in postinfectious FD patients.

METHODS

We enrolled 136 consecutive patients diagnosed with FD according to Rome III criteria, and 20 healthy controls, after upper GI endoscopy. Gastric motility was evaluated by gastric emptying time (T-max) using the (13)C-acetate breath test. Upper abdominal symptoms including epigastric pain, epigastric burning, postprandial fullness, abdominal distension, and early satiety were assessed by questionnaire scores. We obtained biopsy specimens from the stomach and duodenum during upper GI endoscopy. Histological gastritis and duodenitis were assessed as mild, moderate, or severe according to previously described criteria. Characteristics of inflammatory cells and neuroendocrine cells were determined immunohistochemically with antibodies to CD3, CD68, CCR2, Vdelta1 TCR, and serotonin.

RESULTS

Endoscopic duodenitis was observed in only 5.7% of postinfectious FD patients. However, the rates of histological duodenitis in duodenal biopsies of postinfectious FD patients were 17% for mild, 26% for moderate, and 57% for severe grades of duodenitis. The degree of histological duodenitis of postinfectious FD patients was significantly greater than that of healthy volunteers. There was a significant correlation between epigastric burning and the degree of duodenitis in postinfectious FD patients. There was no significant difference in histological duodenitis and T-max value in the postinfectious FD patients with or without Helicobacter pylori infection. In addition, CD68-positive cell number in postinfectious FD patients was significantly increased compared with the numbers in subjects with epigastric pain syndrome or postprandial distress syndrome and in healthy volunteers. CCR2-/CD68-double positive cell number in postinfectious FD patients was significantly (P=0.009) increased compared with those in healthy volunteers.

CONCLUSIONS

Migration of inflammatory cells, in particular, duodenal CCR2-positive macrophages, may have an important function in the pathophysiology of postinfectious FD patients.

Cross-talk and sensitization of bladder afferent nerves

The coordination of pelvic physiologic function requires complex integrative sensory pathways that may converge both peripherally and/or centrally. Following a focal, acute irritative or infectious pelvic insult, these same afferent pathways may produce generalized pelvic sensitization or cross-sensitization as we show bi-directionally for the bladder and bowel in an animal model. Single unit bladder afferent recordings following intracolonic irritation reveal direct sensitization to both chemical and mechanical stimuli that's dependent upon both intact bladder sensory (C-fiber) innervation and neuropeptide content. Concurrent mastocytosis (preponderantly neurogenic) likely plays a role in long-term pelvic organ sensitization via the release of nociceptive and afferent-modulating molecules. Prolonged pelvic sensitization as mediated by these convergent and antidromic reflexive pathway may likewise lead to chronic pelvic pain and thus the overlap of chronic pelvic pain disorders.

Duodenal mastocytosis, eosinophilia and intraepithelial lymphocytosis as possible disease markers in the irritable bowel syndrome and functional dyspepsia

BACKGROUND

Irritable bowel syndrome (IBS) and functional dyspepsia (FD) are common functional disorders without defined pathology. Mast cells and eosinophils interact with T lymphocytes and may alter enteric nerve and smooth muscle function.

AIM

To examine mast cell, eosinophil and intraepithelial lymphocyte populations in duodenal biopsies of subjects with IBS and FD.

METHODS

A random sample of an adult Swedish population (n = 1001; mean age 54 years; 51% female) underwent upper endoscopy and biopsy; 51 cases with FD and 41 cases with IBS were compared with 48 randomly selected controls. Eosinophils were identified by light microscopy; mast cells by immunocytochemistry (CD117). Intraepithelial lymphocytes were counted per 100 enterocytes. Cell counts were quantified by counting the number per high power field (HPF) in 5HPFs in the bulb (D1) and second part of duodenum (D2), summed over 5HPFs at each site.

RESULTS

Cases and controls showed similar demographics. Compared to controls, IELs in IBS-constipation were significantly increased (P = 0.005). Mast cells were significantly increased in IBS in D2 (P < 0.001), while eosinophils were significantly increased in FD in D1 and D2 (P < 0.001).

CONCLUSION

Duodenal mast cell hyperplasia is linked to IBS and eosinophilia to FD, and duodenal biopsy may identify subsets of these disorders.

Enterochromaffin cell hyperplasia in irritable pouch syndrome

BACKGROUND

Irritable pouch syndrome (IPS) is a functional disease in patients with ileal pouch-anal anastomosis following colectomy for ulcerative colitis (UC). The pathophysiology of IPS is characterized by the presence of visceral hypersensitivity, similar to that seen in irritable bowel syndrome. However, the exact etiology and pathogenesis of IPS are not known. We hypothesized that serotonin-containing enteroendocrine cells or enterochromaffin (EC) cell hyperplasia and alterations in the mucosal immune cells may contribute to the patients' symptoms. The aim of the study was to assess EC cell hyperplasia and alterations in the mucosal immune cells in IPS.

METHODS

The Pouchitis Disease Activity Index (PDAI) was used to quantify symptoms and mucosal inflammation in 36 patients with IPS and 25 patients with normal pouches. The histology and immunohistochemistry of pouch mucosal biopsies were assessed by a blinded gastrointestinal pathologist for intraepithelial lymphocytes (IEL), CD3+ T cells, CD25- (interleukin [IL]-2 receptor), tryptase- (mast cells), and serotonin-expressing cells. The numbers of IEL and immune-stained cells were compared between the two groups.

RESULTS

Both groups were compatible demographically in terms of age, gender, duration of UC, stage, indication, and duration of the pouch surgery. There were no differences in the number of IEL, CD3+ T cells, CD25+ cells, and mast cells between the IPS and normal control groups. However, there were a significantly larger number of EC cells in the IPS group than that in the control group (54.8 +/- 24.9 vs 36.7 +/- 17.5 per 4 200x epithelial cells, P < 0.005). The number of EC cells appeared to be correlated with the symptom score (r = 0.276, P= 0.032). There were no significant correlations between the PDAI endoscopy and histology scores and the number of EC cells or between the PDAI scores and the number of IEL or other immune-stained cells.

CONCLUSIONS

A greater number of EC cells were found in the IPS group than the normal pouch group, and the number of EC cells appeared to be correlated with the clinical symptoms of IPS. EC cell hyperplasia may be a contributing mechanism of visceral hypersensitivity and symptoms in IPS.

Functional gastrointestinal disorders and the potential role of eosinophils

The eosinophil-mast cell-neural pathway may be important in the pathophysiology of functional gastrointestinal disorders characterized by unexplained abdominal pain, disordered defecation, or meal-related discomfort. There is evidence that duodenal eosinophils are increased in functional dyspepsia, whereas mast cells are increased in the lower gut in irritable bowel syndrome, directly supporting a role for a hypersensitivity-type reaction in these disorders. The trigger may be a pathogen, food, or other allergen in the gut mucosa. This trigger may evoke eosinophils, mast cells, and other components to cascade to up-regulate serotonin release, with modulation of the enteric and central nervous systems, creating a vicious cycle. If correct, this theory suggests treatment should specifically target the eosinophil-mast cell pathway.

Neuro-immune interactions in inflammatory bowel disease and irritable bowel syndrome: future therapeutic targets

The gastro-intestinal tract is well known for its largest neural network outside the central nervous system and for the most extensive immune system in the body. Research in neurogastroenterology implicates the involvement of both enteric nervous system and immune system in symptoms of inflammatory bowel disease and irritable bowel syndrome. Since both disorders are associated with increased immune cell numbers, nerve growth and activation of both immune cells and nerves, we focus in this review on the involvement of immune cell-nerve interactions in inflammatory bowel disease and irritable bowel syndrome. Firstly, the possible effects of enteric nerves, especially of the nonadrenergic and noncholinergic nerves, on the intestinal immune system and their possible role in the pathogenesis of chronic intestinal inflammatory diseases are described. Secondly, the possible effects of immunological factors, from the innate (chemokines and Toll-like receptors) as well as the adaptive (cytokines and immunoglobulins) immune system, on gastro-intestinal nerves and its potential role in the development of inflammatory bowel disease and irritable bowel syndrome are reviewed. Investigations of receptor-mediated and intracellular signal pathways in neuro-immune interactions might help to develop more effective therapeutic approaches for chronic inflammatory intestinal diseases.

Enhanced expression of mast cell growth factor and mast cell activation in the bladder following the resolution of trinitrobenzenesulfonic acid (TNBS) colitis in female rats

AIMS

Chronic pelvic pain disorders often overlap. We have shown that acute colonic irritation can produce acute irritative micturition patterns and acutely sensitize bladder afferent responses to mechanical and chemical stimuli. We hypothesize that with time, colonic irritation can lead to neurogenic changes in the bladder and the development of chronic bladder sensitization.

METHODS

Micturition patterns were measured in rats 60-90 days after the induction of trinitrobenzenesulfonic acid (TNBS) colitis in the resolution phase of this model. Total and activated mast cells (MCs) were quantified in the bladder, while mRNA levels of stem cell factor (SCF; a.k.a. MC growth factor) and nerve growth factor (NGF; a MC and nociceptive C-fiber stimulator) were quantified in the bladder and L6-S1 dorsal root ganglia (DRG).

RESULTS

Following intra-rectal TNBS, voiding volume was reduced (P < 0.005), while voiding frequency was increased (P < 0.05), both by approximately 50%. Furthermore, both the percentage and density of activated bladder MCs were significantly elevated (P < 0.05), although total MC counts were not statistically increased. At the molecular level, urinary bladder SCF expression increased twofold (P < 0.005), as did NGF (P < 0.01), while L6-S1 DRG levels were not significantly elevated.

CONCLUSIONS

Chronic cystitis in the rat as evidenced by changes in micturition patterns and the recruitment of activated MCs can occur during the resolution phase of TNBS colitis. These changes, of which MCs may play an important role, appear to be maintained over time and may occur via stimulation of convergent pelvic afferent input resulting in the upregulation of neurotrophic factors in the target organ.

Daily stress and gastrointestinal symptoms in women with irritable bowel syndrome

BACKGROUND

Stress has been implicated as contributing to the initiation and exacerbation of bowel and discomfort symptoms in patients with irritable bowel syndrome (IBS).

OBJECTIVE

To examine the relationships of daily self-reported stress to gastrointestinal (GI) and psychological distress symptoms both across women and within woman in a comparison group of women without IBS and among subgroups of women with IBS.

METHODS

Women with IBS (n = 181; age = 18-49 years) who were divided into subgroups based on bowel pattern (constipation, n = 52; diarrhea, n = 67; alternating, n = 62) were compared to a group of women without IBS (n = 48). Self-report stress measures; abdominal (abdominal pain, bloating, and intestinal gas), bowel pattern (constipation, diarrhea), and intestinal gas; and psychological (anxiety and depression) distress symptoms were obtained daily over 1 month. Across-women and within-woman analyses were used.

RESULTS

There were significant across-women correlations among mean daily stress, psychological distress, and GI symptoms in the total IBS group and the IBS bowel pattern subgroups. The across-women relationships between daily stress and GI symptoms were diminished when anxiety and depression were controlled in the analyses. Within-woman analyses showed little evidence of relationship between day-to-day variations in stress and day-to-day variations in GI symptoms; however, stress was strongly related to anxiety and depression.

DISCUSSION

Gastrointestinal symptom distress is associated with self-reported stress in women with IBS. Psychological distress moderates the effects of stress on GI symptoms. The IBS treatment protocols that incorporate strategies that decrease stress and psychological distress are likely to reduce GI symptoms.

Non-ulcer dyspepsia and duodenal eosinophilia: an adult endoscopic population-based case-control study

BACKGROUND & AIMS

Functional abnormalities of the duodenum have been observed in non-ulcer dyspepsia. We aimed to identify whether eosinophils in the upper gastrointestinal tract are a biomarker for non-ulcer dyspepsia.

METHODS

A random sample of an adult Swedish population (n = 1001; mean age, 54 y; 51% female) underwent upper endoscopy. Non-ulcer dyspepsia cases (n = 51, Rome II) and randomly selected controls (n = 48) were identified. Two blinded independent observers assessed the gastroduodenal eosinophil counts. Eosinophils were quantified by counting the number per 5 high-power fields at each of 5 sites (cardia, body, antrum, D1 duodenal bulb, and D2 second portion of duodenum), and total counts were summed over the 5 fields at each site.

RESULTS

The odds ratio for non-ulcer dyspepsia (vs asymptomatic controls) in subjects with high duodenal bulb eosinophil counts (median, >/=22, relative to <22) was 11.7 (95% confidence interval, 3.9-34.9), adjusting for age, sex, and H pylori; similar results were observed in D2 (odds ratio = 7.3; 95% confidence interval, 2.9-18.1). A significant association with the number of eosinophil clusters was detected in the duodenum, with higher values in non-ulcer dyspepsia (P < .01). By immunostaining with major basic protein antibody in a subset of duodenal biopsy specimens, eosinophil degranulation was observed in non-ulcer dyspepsia (7 of 15 vs 0 of 5 controls; P = .11). Gastric eosinophil counts were overall not significantly increased in non-ulcer dyspepsia vs controls. Early satiety was associated with eosinophilia in D1 (P = .01) and D2 (P = .02), adjusting for age, sex, and H pylori.

CONCLUSIONS

Duodenal eosinophilia may characterize a subset of adults with non-ulcer dyspepsia.

Mast cells and nerves tickle in the tummy: implications for inflammatory bowel disease and irritable bowel syndrome

Mast cells are well known as versatile cells capable of releasing and producing a variety of inflammatory mediators upon activation and are often found in close proximity of neurons. In addition, inflammation leads to local activation of neurons resulting in the release neuropeptides, which also play an important immune modulatory role by stimulation of immune cells. In intestinal disorders like inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), the number of mast cells is known to be much higher than in the normal intestine. Moreover, both these disorders are also reported to be associated with alterations in neuropeptide content and in neural innervation. Mutual association between mast cells and enteric nerves has been demonstrated to be increased in pathophysiological conditions and contribute to spreading and amplification of the response in IBD and IBS. In this review the focus lies on studies appointed to the direct interaction between mast cells and nerves in IBD, IBS, and animal models for these disorders so far.

[Stress-mast cell axis and regulation of gut mucosal inflammation: from intestinal health to an irritable bowel]

The functional gastrointestinal disorders and the irritable bowel syndrome, in particular, represent one of the commonest causes of medical consultation and the most frequent diagnosis raised by the gastroenterologists. Despite their high prevalence, the aetiology and pathophysiology of these functional digestive disorders remains unclear and specific diagnostic markers and clearly effective therapeutic options are lacking as well. These factors generate an important impairment in the quality of life in these patients and a growing sanitary burden. Recent studies showing the presence of low grade intestinal mucosal inflammation along with mast cell hyperplasia may contribute to the development and perpetuation of visceral hypersensitivity and dismotility patterns and epithelial barrier abnormalities, characteristic of the irritable bowel syndrome. In this article we will review the role of the stress-mast cell axis in the modulation of the gut mucosal inflammation and in the pathophysiology of the irritable bowel syndrome.

Chronic administration of galanin attenuates the TNBS-induced colitis in rats

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory disorder considered as a consequence of an aberrant response of the immune system to luminal antigens. Numerous groups of agents are being evaluated as novel therapeutic approaches for its treatment; in this way, different peptides have emerged as potential candidates. Galanin is an active neuropeptide distributed in the central and periphery nervous systems although it has been also described having important autocrine and paracrine regulatory capacities with interesting inflammatory and immune properties. In this line, we have observed that galanin treatment has a significant preventive effect in the experimental trinitrobenzensulfonic acid (TNBS) acute model of inflammatory colitis. The aim of the present study was to investigate intensively the role played by the peptide in the evolution of the inflammatory pathology associated to IBD. Galanin (5 and 10 microg/kg/day) was administered i.p., daily, starting 24 h after TNBS instillation, and continuing for 14 and 21 days. The lesions were blindly scored according to macroscopic and histological analyses and quantified as ulcer index. The results demonstrated that chronic administration of galanin improved the colon injury than the TNBS induced. The study by Western-blotting of the expression of nitric oxide inducible enzyme (iNOS), as well as the total nitrite production (NO) assayed by Griess-reaction, showed significant reduction associated with peptide administration. The number of mast cells was also identified in histological preparations stained with toluidine blue and the results showed that samples from galanin treatment, mostly at 21 days, had increased the number of these cells and many of them had a degranulated feature. In conclusion, chronic administration of galanin is able to exert a beneficial effect in the animal model of IBD assayed improving the reparative process. Participation of nitric oxide pathways and mucosal mast cells can not be discarded.

Sensitization of pelvic nerve afferents and mast cell infiltration in the urinary bladder following chronic colonic irritation is mediated by neuropeptides

Irritable bowel syndrome and interstitial cystitis frequently overlap. We have shown that acute colitis sensitizes urinary bladder afferents to both mechanical and chemical stimuli and that chronic colitis similarly produces neurogenic cystitis. We hypothesize that chronic irritation of the colon releases neuropeptides from bladder afferents, leading to receptor sensitization and neurogenic inflammation. Female Sprague-Dawley rats received intrarectal trinitrobenzenesulfonic acid (TNBS) or vehicle 3 days following either systemic capsaicin (CP) pretreatment or vehicle. Ten days later, action potentials of single-unit pelvic C-fiber afferents with receptive fields in the bladder were recorded under urethane anesthesia during graded bladder distensions (UBD) or intravesical capsaicin (vCP) administration. In controls, UBD increased bladder afferent firing in proportion to intravesical pressure. At intravesical pressures of 30 mmHg and above, the percent increase in afferent firing was significantly accentuated following TNBS compared with controls (1,222 ± 176 vs. 624 ± 54%, P < 0.01). The response to vCP was also enhanced (4,126 ± 775 vs. 1,979 ± 438%, P < 0.01). Systemic depletion of neuropeptides from sensory nerves abolished these effects. Histological examination of the bladders revealed an increase in mast cell density in TNBS-treated animals compared with controls (18.02 ± 1.25 vs. 3.11 ± 0.27 mast cells/×100 field, P < 0.01). This effect was significantly ameliorated with CP (10.25 ± 0.95, P < 0.5 vs. TNBS-treated animals). In summary, chronic colonic irritation in the rat sensitizes urinary bladder afferents to noxious stimuli and causes mast cell infiltration in the bladder. Depletion of neuropeptides from sensory afferents diminishes these effects, suggesting they play an important role.