Histopathological alterations in irritable bowel syndrome

Gastrointestinal biopsy of normal mucosa or nonspecific inflammation and risk of neurodegenerative disease: Nationwide matched cohort study

BACKGROUND AND PURPOSE

Evidence has accumulated to support the early involvement of altered gastrointestinal (GI) function in neurodegenerative disease. However, risk of Alzheimer disease (AD) and Parkinson disease (PD) among individuals with a GI biopsy of normal mucosa or nonspecific inflammation is unknown.

METHODS

This matched cohort study included all individuals in Sweden with a GI biopsy of normal mucosa (n = 480,346) or nonspecific inflammation (n = 655,937) during 1965-2016 (exposed group) as well as their individually matched population references and unexposed full siblings. A flexible parametric model and stratified Cox model were used to estimate hazard ratio (HR) and its 95% confidence interval (CI).

RESULTS

Individuals with normal mucosa or nonspecific inflammation had a higher risk of AD and PD during the 20 years after biopsy. Compared with the population references, individuals with normal mucosa had an increased risk of AD (incidence rate [IR] difference = 13.53 per 100,000 person-years, HR [95% CI] = 1.15 [1.11-1.20]) and PD (IR difference = 6.72, HR [95% CI] = 1.16 [1.10-1.23]). Elevated risk was also observed for nonspecific inflammation regarding AD (IR difference = 13.28, HR [95% CI] = 1.11 [1.08-1.14]) and PD (IR difference = 6.83, HR [95% CI] = 1.10 [1.06-1.14]). Similar results were observed in subgroup and sensitivity analyses and when comparing with their unexposed siblings.

CONCLUSIONS

Individuals with a GI biopsy of normal mucosa or nonspecific inflammation had an increased risk of AD and PD. This adds new evidence of the early involvement of GI dysfunction in neurodegenerative disease.

Vagus Nerve Stimulation Relives Irritable Bowel Syndrome and the Associated Depression via α7nAChR-mediated Anti-inflammatory Pathway

OBJECTIVES

The present study is designed to investigate the role of vagus nerve in the treatments of irritable bowel syndrome (IBS) and the associated central nervous system disorders.

METHODS

An IBS animal model was established by giving acetic acid and chronic-acute stress (AA-CAS) treatment in adult male Wistar rats. Subdiaphragmatic vagotomy (SDV) and vagus nerve stimulation (VNS) were performed to intervene the excitability of vagus nerve. Permeability of blood brain barrier (BBB) was measured and agonist and antagonist of α7 nicotinic acetylcholine receptor (α7nAChR) were used to explore the relevant mechanisms.

RESULTS

AA-CAS treatment resulted in abnormal fecal output, increased visceral sensitivity, depressive-like behaviors, and overexpression of inflammatory mediators, all of which were reversed by VNS treatment. The effects of VNS could also be observed when α7nAChR agonist was applied. Whereas α7nAChR antagonist (methyllycaconitine, MLA) reversed VNS's effects. Interestingly, VNS also reduced the increased permeability of blood brain barrier (BBB) following AA-CAS treatment in IBS rats. SDV treatment only show temporary efficacy on AA-CAS-induced symptoms and had no effect on the permeability of BBB.

CONCLUSION

The intestinal abnormalities and depressive symptoms in IBS rats can be improved by VNS treatment. This positive effect of VNS was achieved through α7nAChR-mediated inflammatory pathway and may also be associated with the decreased of BBB permeability.

Cannabidiol and Intestinal Motility: a Systematic Review

Cannabidiol (CBD) is a non-intoxicating cannabinoid extracted from the cannabis plant that is used for medicinal purposes. Ingestion of CBD is claimed to address several pathologies, including gastrointestinal disorders, although limited evidence has been generated thus far to substantiate many of its health claims. Nevertheless, CBD usage as an over-the-counter treatment for gastrointestinal disorders is likely to expand in response to increasing commercial availability, permissive legal status, and acceptance by consumers. This systematic review critically evaluates the knowledge boundaries of the published research on CBD, intestinal motility, and intestinal motility disorders. Research on CBD and intestinal motility is currently limited but does support the safety and efficacy of CBD for several therapeutic applications, including seizure disorders, inflammatory responses, and upper gastrointestinal dysfunction (i.e., nausea and vomiting). CBD, therefore, may have therapeutic potential for addressing functional gastrointestinal disorders. The results of this review show promising in vitro and preclinical data supporting a role of CBD in intestinal motility. This includes improved gastrointestinal-related outcomes in murine models of colitis. These studies, however, vary by dose, delivery method, and CBD-extract composition. Clinical trials have yet to find a conclusive benefit of CBD on intestinal motility disorders, but these trials have been limited in scope. In addition, critical factors such as CBD dosing parameters have not yet been established. Further research will establish the efficacy of CBD in applications to address intestinal motility.

A model for irritable bowel syndrome and anxiety comorbidities in relation to alcohol use disorders

About 95% of human body serotonin synthesis occurs in the gastrointestinal tract (GI). Lack of sufficient serotonin levels is thought to play a key role in mood disorders, including anxiety disorders. In this study, we looked at a disorder affecting the GI tract, irritable bowel syndrome (IBS), and aimed to determine whether IBS is differentially associated with anxiety disorders in 252 chronic pain patients in the presence of a history of alcohol use disorders (AUD) given that alcohol is an extremely aggressive substance for the GI mucosa. We found that while the prevalence of IBS was not affected by the presence of AUD in chronic pain patients, IBS had significantly higher comorbidity with anxiety disorders in chronic pain patients with comorbid alcohol use disorders. We argue that these findings highlight mechanistic differences in the comorbidity of anxiety disorders with chronic pain and AUD, implicating a central role for GI problems stemming from chronic alcohol use. The findings may have important implications for the treatment of IBS patients with AUD who commonly present with anxiety disorders which could motivate the continuation of problematic drinking and impede recovery success. We propose that addressing GI problems in patients with AUD may help manage AUD and recovery more effectively.

Vitamin D and lactoferrin attenuate stress-induced colitis in Wistar rats via enhancing AMPK expression with inhibiting mTOR-STAT3 signaling and modulating autophagy

Irritable bowel syndrome (IBS) is a global gastrointestinal disorder closely related to psychological stress exposure and local colonic inflammation. Herein, we investigated the effect of wrap-restraint stress (WRS) on rat behavior, on adenosine monophosphate-activated protein kinase-mammalian/mechanistic target of rapamycin-signal transducer and activator of transcription 3 (AMPK-mTOR-STAT3) signaling, and autophagy in colonic mucosa. The impact of chronic administration of vitamin D₃ and lactoferrin was compared. Twenty-four male Wistar rats were randomly divided into four groups. Chronic WRS protocol was applied as a rodent model of IBS. Group I: naïve animals, Group II: WRS animals, Group III: WRS-exposed and treated with vitamin D₃ (500 IU/kg/day), and Group IV: WRS-exposed and treated with lactoferrin (300 mg/kg/day). In this study, we found that chronic administration of each of vitamin D₃ and lactoferrin resulted in a significant increase in social interaction test, interleukin-10, AMPK, optical density of LC3B, goblet cell count and marked decrease in serum cortisol level, STAT3, inflammatory cell count, and optical density of mTOR in comparison to the WRS rats. Our findings suggest that both vitamin D₃ and Lactoferrin could augment colonic autophagy through enhanced AMPK expression and inhibition of mTOR-STAT3 signaling, which offers practical insights into their clinical use in the prevention and therapy of IBS. However, lactoferrin intake as a nutritional supplement could be more helpful for stress-induced colitis treatment than vitamin D_3.

The Prevalence and Incidence of Irritable Bowel Syndrome and Inflammatory Bowel Disease in Depression and Bipolar Disorder: A Systematic Review and Meta-Analysis

OBJECTIVE

The increased prevalence and incidence of affective disorders among patients with gastrointestinal disease have been well established. However, few studies have investigated the inverse relationship. We aimed to identify all pieces of evidence of the prevalence and incidence of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) in people with depression and bipolar disorder.

METHODS

We conducted a systematic review of studies reporting the association between affective disorders (exposure) and IBS or IBD (outcome) in adults. Evidence was evaluated for quality using Joanna Briggs Institute Critical Appraisal tools. Where suitable data were available, meta-analyses were performed.

RESULTS

We identified 18 studies that met the selection criteria, of which 11 provided data on IBS, 5 on IBD, and 2 on both. Overall, people with depression were significantly more likely to have comorbid IBS (risk ratio = 2.42, 95% confidence interval = 1.98-2.96) and to develop new-onset IBS (risk ratio = 1.90, 95% confidence interval = 1.41-2.56) compared with people without depression. They were also more likely to have and develop IBD, and among patients with IBD, significantly increased rates of depression were observed as early as 5 years before diagnosis. Bipolar disorder was not consistently associated with risk of either condition.

CONCLUSIONS

People with depression are at an increased risk of both having and developing lower gastrointestinal disorders. These findings have important implications for how we understand, manage, and prevent this comorbidity in clinical practice. Further studies are needed to improve our understanding of the relationship between bipolar disorder and bowel disease as well as the role of psychotropic medication, particularly selective serotonin reuptake inhibitors.

Identification of a Pain-Specific Gene Expression Profile for Pediatric Recurrent Abdominal Pain

Objectives: Functional Abdominal Pain (FAP) and Irritable Bowel Syndrome (IBS) are common recurrent abdominal pain diagnoses with the hallmark, lack of inflammation. To identify a biological signature for IBS/FAP in the colon, this study used genetic profiling to uncover gene expression changes associated with IBS/FAP and abdominal pain. Methods: Patients (8 to 17 years) newly diagnosed with IBS or FAP were enrolled in the study. At diagnostic colonoscopy, three rectal biopsies were collected, and gene expression analysis was performed using a Qiagen PCR Array. Relative fold difference in gene expression for 84 pain-associated genes was calculated using the 2-ΔΔ Cq method compared with pain-free controls. Factors affecting pain burden (Pain Burden Interview; PBI) were analyzed, including age, sex, rectal inflammation, and gene expression. Data were analyzed using multiple stepwise linear regression and 2-tailed t tests (P ≤ 0.05). Results: Of the 22 total patients in the study, 19 were diagnosed with either IBS-Constipation (frequency of 5.26%), IBS-Diarrhea (47.37%), IBS-Mixed (10.53%), or FAP (36.84%). IBS/FAP patients reported significantly higher pain burden at the time of diagnosis compared to pain-free controls (p < 0.001), as well as significantly higher abdominal pain (p = 0.01). Of the 84 genes, expression of GRIN1 (p = 0.02), MAPK3 (p = 0.04), P2X4 (p = 0.04), and PTGES3 (p = 0.02) were all significantly associated with PBI score. Discussion: Abdominal pain associated with IBS/FAP in pediatric patients may be linked to the expression of GRIN1, MAPK3, P2X4, and PTGES3, pointing to potential novel therapeutic targets for management of recurring abdominal pain.

The role of intestinal mast cell infiltration in irritable bowel syndrome

As an essential part of the immune system, mast cells (MCs) play an important role in the pathogenesis of irritable bowel syndrome (IBS). Accumulating evidence has identified altered MC count and density in intestinal mucosa of patients with IBS; however, conflicting findings yield inconsistent conclusions. Currently, most studies have suggested intestinal MC infiltration in IBS patients. Considering the pivotal role of MCs in IBS, it is necessary to achieve a better understanding about the pathological changes in the intestine. The risk factors for IBS, including dietary habits, psychological factors, infection, and dysbiosis, are implicated to induce intestinal MC infiltration. Mechanistically, food may trigger immune-related allergic reactions and affect the intestinal microbiota activity. Some exogenous pathogens and altered profile of commensal bacteria promote intestinal MC recruitment through promoted release of chemokines from epithelial cells or direct activation of the immune system. In addition, psychological factors may affect the microenvironment where MCs live. MCs have been proven to interact with the enteric neurons and other immunocytes, evidenced by the close proximity of MCs to neurons and regional altered immune system components. A variety of mediators released by the enteric neurons, immunocytes, and MCs per se, such as neurotrophins, neuropeptides, cytokines, and chemokines, may have stimulant effects on MCs by modulating the survival, proliferation, and recruitment process of MCs in the intestine. In this review, the associations between IBS and intestinal MC density and the underlying mechanisms are discussed.

Mortality Risk in Irritable Bowel Syndrome: Results From a Nationwide Prospective Cohort Study

INTRODUCTION

Mortality concern is a frequent driver of care seeking in patients with irritable bowel syndrome (IBS). Data on mortality in IBS are scarce, and population-based studies have been limited in size. We examined mortality in IBS.

METHODS

A nationwide, matched, population-based cohort study was conducted in Sweden. We identified 45,524 patients undergoing a colorectal biopsy at any of Sweden's 28 pathology departments and with a diagnosis of IBS from 2002 to 2016 according to the National Patient Register, a nationwide registry of inpatient and outpatient specialty care. We compared the mortality risk between these individuals with IBS and age- and sex-matched reference individuals (n = 217,316) from the general population and siblings (n = 53,228). In separate analyses, we examined the role of mucosal appearance for mortality in IBS. Finally, we examined mortality in 41,427 patients with IBS not undergoing a colorectal biopsy. Cox regression estimated hazard ratios (HRs) for death.

RESULTS

During follow-up, there were 3,290 deaths in individuals with IBS (9.4/1,000 person-years) compared with 13,255 deaths in reference individuals (7.9/1,000 person-years), resulting in an HR of 1.10 (95% confidence interval [CI] = 1.05-1.14). After adjustment for confounders, IBS was not linked to mortality (HR = 0.96; 95% CI = 0.92-1.00). The risk estimates were neutral when patients with IBS were compared with their siblings. The underlying mucosal appearance on biopsy had only a marginal impact on mortality, and patients with IBS not undergoing a colorectal biopsy were at no increased risk of death (HR = 1.02; 95% CI = 0.99-1.06).

DISCUSSION

IBS does not seem to confer an increased risk of death.

Marshall and Warren Lecture 2019: A paradigm shift in pathophysiological basis of irritable bowel syndrome and its implication on treatment

Irritable bowel syndrome (IBS), a common functional gastrointestinal disorder (FGID), has often been considered rather inappropriately as psychogenic in the past. Though psychological issues are important comorbidities in a proportion of IBS patients, the evidences are far from enough to label this condition as psychogenic only. In the recent past, evidences are emerging that underscores the concept supporting pure psychogenic theory of IBS and suggest this disorder to be rather microorganic. Accordingly, a move of Rome IV Committee attempting to delete the term "functional" and designating these to be disorders of "gut-brain interaction" rather than that of "brain-gut interaction," it emphasizes the importance of the gut over the brain in the pathogenesis. The introduction of the concept of multidimensional clinical profile in Rome IV requires attention to diagnostic category of FGID, overlap, severity, psychological issues, and physiological dysfunction or biomarkers; this attempts to recognize clinical variability and multidimensionality of pathophysiology and management of these disorders. The recognition of the biological factors in the pathogenesis of IBS is a significant paradigm shift in the recent time. This is somewhat similar to the progress in the pathogenesis of peptic ulcer disease from psychological factor to acid to Helicobacter pylori infection. It is expected that in the near future, therapeutic modalities targeting the different pathogenic mechanisms of different subtypes of IBS may bring revolution in management of the disorder.

Assessment of Citations of the Retracted Article by Wakefield et al With Fraudulent Claims of an Association Between Vaccination and Autism

IMPORTANCE

The number of citations can be used to show the influence of an article or to measure the validity of a research study. The article by Wakefield et al that fraudulently reported an association between vaccination and autism continues to accumulate citations even after it was retracted.

OBJECTIVES

To examine the characteristics of citations from scholarly literature that reference the 1998 article by Wakefield et al and to investigate whether authors are accurately citing retracted references.

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional bibliographic analysis of the scholarly publications that cited a 1998 article by Wakefield et al, cited references were collected from a Web of Science Core Collection search performed on March 11, 2019. A total of 1211 articles were identified, with 58 citing works excluded because they were non-English-language publications or the citation to the study by Wakefield et al could not be located by reviewers. Citing works consisted of books, research articles, letters, editorials, news items, and other scholarly literature. Citations to the article by Wakefield et al were identified and analyzed by 2 reviewers in a blinded screening. Reviewers assigned a characteristic to each citation and indicated whether the retraction was documented.

MAIN OUTCOMES AND MEASURES

The characteristics of citations to the article by Wakefield et al, were categorized as negative, affirmative, or contrastive; if not, persuasive; and if not, assumptive, perfunctory, methodologic, or conceptual. Whether the partial retraction or notice of retraction was included in the citing work was also documented.

RESULTS

Among the 1153 citing works included in this analysis, the most common citation characteristics were negative (838 [72.7%]) followed by perfunctory (106 [9.2%]) and affirmative (94 [8.2%]). A total of 123 of 322 citing works (38.2%) published between 2005 and 2010 documented the partial retraction. After the notice of retraction was published in 2010, the percentage of citing works that documented the partial retraction and/or notice of retraction between 2011 and 2018 increased to 360 of 502 (71.7%).

CONCLUSIONS AND RELEVANCE

Since the article by Wakefield et al was initially published, authors have mostly negated the findings of the study. A significant number of authors did not document retractions of the article by Wakefield et al. The findings suggest that improvements are needed from publishers, bibliographic databases, and citation management software to ensure that retracted articles are accurately documented.

Inflammatory cell distribution in colon mucosa as a new tool for diagnosis of irritable bowel syndrome: A promising pilot study

BACKGROUND

Currently, there are no histological criteria to diagnose irritable bowel syndrome (IBS). Our aims were (i) to examine the distribution of inflammatory cells in the colon of healthy and IBS subjects and (ii) to find histological diagnosis criteria for IBS.

METHODS

Colonic biopsies were taken from four distinct regions of the colon from 20 controls (HC) and 11 patients with IBS (4 with constipation (IBS-C) and 7 with diarrhea (IBS-D) and embedded in paraffin. Macrophages, mast cells, eosinophils, and T lymphocytes were immunostained and positive cells counted.

KEY RESULTS

In both HC and IBS patients, global cellularity decreased from the cecum to the rectum (P < .01) which is attributed to reduced number of macrophages (P < .05) and eosinophils (P < .001) but not T cells. Mast cells were reduced in IBS (P < .05) but not in HC, particularly in IBS-D (P < .05). Results showed higher number of macrophages in the left colon of IBS subjects than HC (P < .05).

CONCLUSION & INFERENCES

Here we report a decreasing gradient of immune cells from the cecum to the rectum of the human colon. Although global cellularity cannot be used to distinguish between IBS and HC, closer analysis of macrophages and mast cells may be useful markers to confirm IBS histologically and to differentiate between IBS-C and IBS-D when clinical presentation alternates between constipation and diarrhoea. This pilot study remains to be confirmed with greater number of patients.

Stereotaxic Exposure of the Central Nucleus of the Amygdala to Corticosterone Increases Colonic Permeability and Reduces Nerve-Mediated Active Ion Transport in Rats

Background: Irritable bowel syndrome (IBS) is characterized by visceral pain and abnormal bowel habits that are worsened during stress. Evidence also suggests altered intestinal barrier function in IBS. Previously, we demonstrated that stereotaxic application of the stress hormone corticosterone (CORT) onto the central nucleus of the amygdala (CeA) induces colonic hyperalgesia and anxiety-like behavior in a rat model, however the effect on intestinal permeability and mucosal function remain to be evaluated. Methods: Male Fischer 344 rats underwent bilateral stereotaxic implantation of CORT or inert cholesterol (CHOL)-containing micropellets (30 μg) onto the dorsal margin of the CeA. Seven days later, colonic tissue was isolated to assess tissue permeability in modified Ussing chambers via transepithelial electrical resistance (TEER) and macromolecular flux of horseradish peroxidase (HRP). Secretory responses to electrical field stimulation (EFS) of submucosal enteric nerves as well as activation with forskolin were used to assess movements of ions across the isolated colonic tissues. In a separate cohort, colonic histology, and mast cell infiltration was assessed. Key Results: Compared to CHOL-implanted controls, we determined that exposing the CeA to elevated levels of CORT significantly increased macromolecular flux across the colonic epithelial layer without changing TEER. Nerve-mediated but not cAMP-mediated active transport was inhibited in response to elevated amygdala CORT. There were no histological changes or increases in mast cell infiltration within colonic tissue from CORT treated animals. Conclusion and Inferences: These observations support a novel role for the CeA as a modulator of nerve-mediated colonic epithelial function.

The role of inflammation in irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) is a complex, functional gastrointestinal disorder characterized by chronic abdominal pain or discomfort and altered bowel habits. Despite the global prevalence and disease burden of IBS, its underlying pathophysiology remains unclear. Inflammation may play a pathogenic role in IBS. Studies have highlighted the persistence of mucosal inflammation at the microscopic and molecular level in IBS, with increased recruitment of enteroendocrine cells. Substantial overlaps between IBS and inflammatory bowel disease have also been reported. This review thus aimed to discuss the body of evidence pertaining to the presence of mucosal inflammation in IBS, its putative role in the disease process of IBS, and its clinical relevance. Increased mast cell density and activity in the gut may correlate with symptoms of visceral hypersensitivity. As evidenced by patients who develop postinfectious IBS, infective gastroenteritis could cause systemic inflammation and altered microbiome diversity, which in turn perpetuates a cycle of chronic, low-grade, subclinical inflammation. Apart from mucosal inflammation, neuroinflammation is probably involved in the pathophysiology of IBS via the "gut-brain" axis, resulting in altered neuroendocrine pathways and glucocorticoid receptor genes. This gives rise to an overall proinflammatory phenotype and dysregulated hypothalamic-pituitary-adrenal axis and serotonergic (5-HT) functioning, which could, at least in part, account for the symptoms of IBS. Although a definite and reproducible pattern of immune response has yet to be recognized, further research into anti-inflammatories may be of clinical value.

Weaning stress and gastrointestinal barrier development: Implications for lifelong gut health in pigs

The gastrointestinal (GI) barrier serves a critical role in survival and overall health of animals and humans. Several layers of barrier defense mechanisms are provided by the epithelial, immune and enteric nervous systems. Together they act in concert to control normal gut functions (e.g., digestion, absorption, secretion, immunity, etc.) whereas at the same time provide a barrier from the hostile conditions in the luminal environment. Breakdown of these critical GI functions is a central pathophysiological mechanism in the most serious GI disorders in pigs. This review will focus on the development and functional properties of the GI barrier in pigs and how common early life production stressors, such as weaning, can alter immediate and long-term barrier function and disease susceptibility. Specific stress-related pathophysiological mechanisms responsible for driving GI barrier dysfunction induced by weaning and the implications to animal health and performance will be discussed.

Transfer of CD11c+ lamina propria mononuclear phagocytes from post-infectious irritable bowel syndrome causes mucosal barrier dysfunction and visceral hypersensitivity in recipient mice

The role of low-grade inflammation in the development of post‑infectious irritable bowel syndrome (PI‑IBS) has attracted increasing attention. Abnormal CD11c+ mononuclear phagocytes, such as dendritic cells (DCs), macrophages, and monocytes, are involved in the disruption of immune tolerance in organisms, which can lead to the development of chronic inflammatory diseases. The present study tested the hypothesis that CD11c+ lamina propria mononuclear phagocytes (CD11c+ LPMPs) contribute to increased mucosal permeability and visceral hypersensitivity in a PI‑IBS mouse model. CD11c+ LPMPs were isolated and purified via the digestion of intestinal tissues and magnetic‑activated cell sorting. We detected increased mucosal permeability, visceral hypersensitivity and intestinal inflammation during both the acute and chronic stages of Trichinella infection. Following the transfer of CD11c+ LPMPs from PI‑IBS mice into normal mice, low‑grade inflammation was detected, as demonstrated by increased IL‑4 expression in the ileum, as well as enhanced mucosal permeability, as indicated by decreased transepithelial electrical resistance and the pre-sence of ultrastructural alterations. More importantly, the mice that underwent adoptive transfer of CD11c+ LPMPs from the PI‑IBS mice also exhibited increased abdominal withdrawal reflex scores and a decreased threshold. Our data demonstrated that the CD11c+ LPMPs from this PI‑IBS mouse model were not only able to transfer enteric inflammation to the normal mice but also caused abnormal intestinal function, characterized by epithelial barrier disruption and visceral hyperalgesia.

Gender Differences in Serotonin Signaling in Patients with Diarrhea-predominant Irritable Bowel Syndrome

Objective Gender differences, including differences in the prevalence, subtypes and the effectiveness of treatment, are generally recognized in irritable bowel syndrome (IBS). Although serotonin type 3 receptor (5-HT3R) antagonists appear to be more effective in women with diarrhea predominant IBS (IBS-D) than they are in men, the mechanisms underlying these effects remain unclear. The aim of the present was to investigate the gender differences in 5-HT signaling. Methods The subjects were selected from outpatients with IBS-D and healthy controls. Their rectal mucosal S100A, tryptophan hydroxylase (TPH) and 5-HT transporter (5-HTT, SERT, SLC6A4) mRNA expression levels were measured. Clinical symptoms were evaluated using the gastrointestinal symptom rating scale (GSRS) and the self-rating depression scale (SDS). Results The study population of 100 subjects included 47 IBS-D patients and 53 age- and gender-matched healthy controls. The S100A9 (5.20 vs. 1.90, p=0.001) and SLC6A4 (2.00 vs. 1.00, p=0.019) mRNA levels in the rectal mucosa of women with IBS-D were significantly higher than those in men. Among the healthy controls, the S100A10 expression levels in men were higher than those in women (1.33 vs. 0.82, p=0.005). The S100A8 and S100A10 expression levels in women with IBS-D were positively correlated with their diarrhea scores (r=0.55 and 0.58, p<0.05). Conclusion 5-HT signaling might be a major contributor to the symptoms of IBS in men, and the differences may be associated with the effectiveness of 5-HT3R antagonists.

Immune dysregulation in the functional gastrointestinal disorders

Gastrointestinal conditions may be broadly classified into two: organic and functional disease, with functional disorders accounting for the majority of patients with chronic gastrointestinal symptoms. Functional gastrointestinal disorders (FGIDs) present with no obvious pathology or well-accepted biochemical mechanism and, as such, treatment strategies are limited and focus on symptoms rather than cure. Irritable bowel syndrome and functional dyspepsia are the most widely recognised FGIDs, and there is a growing body of evidence to suggest an underlying inflammatory phenotype in subsets with these conditions. Here, we discuss the current knowledge of immune involvement in FGIDs and the commonalities between the different manifestations of FGIDs and propose a new hypothesis, potentially defining an underlying immunopathological basis of these conditions.

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.

Review article: Associations between immune activation, intestinal permeability and the irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS), one of the most common gastrointestinal disorders, markedly impairing patients' quality of life. Drug development for IBS treatment has been hampered by the lack of understanding of IBS aetiology. In recent years, numerous data have emerged that suggest the involvement of immune activation in IBS, at least in a subset of patients.

AIM

To determine whether immune activation and intestinal permeabilisation are more frequently observed in IBS patients compared with healthy controls.

METHODS

The scientific bibliography was searched using the following keywords: irritable bowel syndrome, inflammation, immune activation, permeabilisation, intestine, assay, histology and human. The retrieved studies, including blood, faecal and histological studies, were analysed to provide a comprehensive and structured overview of the available data including the type of assay, type of inflammatory marker investigated or intestinal segment studied.

RESULTS

Immune activation was more frequently observed in IBS patients than in healthy controls. An increase in the number of mast cells and lymphocytes, an alteration in cytokine levels and intestinal permeabilisation were reported in IBS patients. No consistent changes in the numbers of B cells or enterochromaffin cells or in mucosal serotonin production were demonstrated.

CONCLUSIONS

The changes observed were modest and often heterogeneous among the studied population. Only appropriate interventions improving irritable bowel syndrome symptoms could highlight and confirm the role of immune activation in this pathophysiology.

The gastroenterologist's view

The traditional view that recurrent episodes of diverticulitis lead to progressively complicated disease resulting in a disadvantageous course, more difficult, complicated operations and lethal outcomes did not stand the test of evidence. Only a minority of patients with acute diverticulitis will ever require surgery, and if so, this occurs during or early after the first episode. Complications and recurrence of disease after surgery are enumerable. Strong indicators favoring sigmoid colectomy are major abscess, free air, and fistula, i.e. perforating disease. This occurs predominantly at the initial presentation, frequently in younger or immunosuppressed patients. Important differential diagnoses must be considered both for initial diagnosis of diverticulitis and for recurrent episodes. Conservative management of recurrent diverticulitis is safe and best guided by gastroenterological expertise. Sophisticated ultrasound experience as a part of this competence allows detailed evaluation of the local status and the best evidence in the literature for diagnosing diverticulitis is on US. In practice, however, the question of perforating diverticulitis is adequately answered by subtle CT scan. Medical therapy is usually the treatment of choice for recurrent diverticulitis. Avoidance of drugs bearing the hazard of perforation (e.g. NSAIDs) is emphasized, and smoking is strongly discouraged. A mathematical model based on published data shows that patients with recurrent diverticulitis overall (only) profit from surgery if they are hit by four episodes during the course of disease. This is where theory and reality (should) meet.

The jejunum of diarrhea-predominant irritable bowel syndrome shows molecular alterations in the tight junction signaling pathway that are associated with mucosal pathobiology and clinical manifestations

OBJECTIVES

Diarrhea-predominant irritable bowel syndrome (IBS-D) patients show altered epithelial permeability and mucosal micro-inflammation in both proximal and distal regions of the intestine. The objective of this study was to determine the molecular events and mechanisms and the clinical role of upper small intestinal alterations.

METHODS

Clinical assessment and a jejunal biopsy was obtained in IBS-D patients and healthy subjects. Routine histology and immunohistochemistry was performed in all participants to assess the number of mast cells (MCs) and intraepithelial lymphocytes. RNA in tissue samples was isolated to identify genes showing consistent differential expression by microarray analysis followed by pathway and network analysis in order to identify the biological functions of the differentially expressed genes in IBS-D. Gene and protein expression of tight junction (TJ) components was also assessed by quantitative real-time polymerase chain reaction and confocal microscopy to evaluate the pathways identified by gene expression analysis.

RESULTS

The analysis reveals a strong association between the transcript signature of the jejunal mucosa of IBS-D and intestinal permeability, MC biology, and TJ signaling. The expression of zonula occludens 1 (ZO-1) was reduced in IBS-D at both gene and protein level, with protein redistribution from the TJ to the cytoplasm. Remarkably, our analysis disclosed significant correlation between ZO proteins, MC activation, and clinical symptoms.

CONCLUSIONS

IBS-D manifestations are linked to molecular alterations involving MC-related dysregulation of TJ functioning in the jejunal mucosa.

Irritable bowel syndrome and food allergy

Irritable bowel syndrome (IBS) is a kind of functional gastrointestinal disease characterized by abdominal pain or discomfort associated with changes in bowel habits. The alternating symptoms of IBS seriously affect the patients' quality of life. Some studies have found that food could cause or aggravate the symptoms of IBS possibly by inducing food allergy and food intolerance. However, the specific mechanisms have not been established yet. Currently there are "bacterial 'toxin' hypothesis", "immune or inflammatory response hypothesis" and "physical or chemical irritation hypothesis" explaining the role of food in the pathogenesis of IBS. It has been known that food factors play a very important role in the pathogenesis of IBS. This article reviews food allergy and the possible mechanisms, diagnosis and treatment of IBS caused by food.

The pathogenic role of different Blastocystis hominis genotypes isolated from patients with irritable bowel syndrome

BACKGROUND AND STUDY AIMS

The pathogenic role of Blastocystis hominis is still regarded by some as controversial. Studies have been in progress for years to evaluate the role of blastocystosis in irritable bowel syndrome (IBS) and demonstrated that faecal carriage of B. hominis was frequent in these patients. This study attempted to distinguish different genotypes of B. hominis isolates obtained from patients with IBS and to evaluate their pathogenic potentials.

PATIENTS AND METHODS

One hundred subjects (51 patients with IBS and 49 asymptomatic infected subjects) harbouring B. hominis were investigated by a direct smear examination and in vitro culture of stool samples followed by genotyping of B. hominis by PCR using STS primers. Sigmoidoscopy was done in all subjects and biopsies were taken and subjected to histopathologic examination.

RESULTS

Genotyping proved that only four genotypes of B. hominis were identified. In patients with IBS, genotypes III, I, and IV were detected (28, 15 and 14 isolates, respectively). On the other hand, genotypes III, IV, and II were identified in asymptomatic infected individuals (21, 19 and 13 isolates, respectively). The degrees of chronic inflammatory changes in sigmoidoscopic biopsies caused by B. hominis genotypes among IBS patients revealed that severe inflammation was present mainly in patients harboring genotype I isolates (4/15) (26.66%), while genotype III caused severe inflammation only in 9.09%. Genotype II isolates were not detected in IBS cases. Asymptomatic infected individuals harboring genotypes II, III and IV exhibited mild to moderate inflammatory changes. Genotype I isolates were not detected in asymptomatic infected group. The correlation between different B. hominis genotypes and degree of inflammation was statistically insignificant.

CONCLUSION

Genotype I was the most pathogenic genotype of B. hominis isolates in patients with IBS while genotype II was not detected among those patients. Also, our results suggest the presence of pathogenic and non-pathogenic strains among genotypes III and IV.

Do Patients with Functional Gastrointestinal Disorders have an Altered Gut Flora?

The description of the de novo development of irritable bowel syndrome (IBS) following an episode of bacterial gastroenteritis (postinfectious IBS) illustrated the potential for a luminal factor (a bacterial pathogen) to cause this common gastrointestinal ailment. As a consequence of these and other observations as well as results of experiments involving animal models, the enteric flora and the immune response that it generates in the host have, somewhat surprisingly, come centre-stage in IBS research with their potential to induce the pathophysiological changes that are associated with IBS. While evidence for immune dysfunction both in the mucosa and systemically continues to accumulate, methodological limitations have hampered a full delineation of the nature of the microbiota in IBS. The latter is eagerly awaited and may yet provide a firm rationale for the use of certain probiotics and antibiotics in IBS, whose benefits have now been described with some consistency.

A closer look at mucosal inflammation in irritable bowel syndrome: sex- and gender-related disparities--quantity, quality, or both?

Irritable bowel syndrome remains a bothersome and frustrating disorder that imposes a heavy and growing socio-economic toll on its sufferers, two-thirds of whom are women, and on health care systems. The biomedical community must take a giant step forward into the discipline of women's gastrointestinal health. Efforts and accomplishments, such as the one reported in this month's issue by Cremon et al., are certainly welcome.

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.

Mycobacterium avium subspecies paratuberculosis infection in cases of irritable bowel syndrome and comparison with Crohn's disease and Johne's disease: common neural and immune pathogenicities

Mycobacterium avium subsp. paratuberculosis causes Johne's disease, a systemic infection and chronic inflammation of the intestine that affects many species, including primates. Infection is widespread in livestock, and human populations are exposed. Johne's disease is associated with immune dysregulation, with involvement of the enteric nervous system overlapping with features of irritable bowel syndrome in humans. The present study was designed to look for an association between Mycobacterium avium subsp. paratuberculosis infection and irritable bowel syndrome. Mucosal biopsy specimens from the ileum and the ascending and descending colon were obtained from patients with irritable bowel syndrome attending the University of Sassari, Sassari, Sardinia, Italy. Crohn's disease and healthy control groups were also included. Mycobacterium avium subsp. paratuberculosis was detected by IS900 PCR with amplicon sequencing. Data on the potential risk factors for human exposure to these pathogens and on isolates from Sardinian dairy sheep were also obtained. Mycobacterium avium subsp. paratuberculosis was detected in 15 of 20 (75%) patients with irritable bowel syndrome, 3 of 20 (15%) healthy controls, and 20 of 23 (87%) people with Crohn's disease (P = 0.0003 for irritable bowel syndrome patients versus healthy controls and P = 0.0000 for Crohn's disease patients versus healthy controls). One subject in each group had a conserved single-nucleotide polymorphism at position 247 of IS900 that was also found in isolates from seven of eight dairy sheep. There was a significant association (P = 0.0018) between Mycobacterium avium subsp. paratuberculosis infection and the consumption of hand-made cheese. Mycobacterium avium subsp. paratuberculosis is a candidate pathogen in the causation of a proportion of cases of irritable bowel syndrome as well as in Crohn's disease.