Is irritable bowel syndrome an inflammatory disorder?

Colonic mucosal eosinophilia and immunohistochemical expression of COX-2 and NF-kB in patients with irritable bowel syndrome

BACKGROUND

There is growing evidence that eosinophilic infiltration can release mediators which are harmful to the intestinal epithelium in patients with irritable bowel syndrome (IBS). Although cyclooxygenase 2 (COX-2) and nuclear factor-kappa beta (NF-kB) expression had been previously reported to increase in many inflammatory conditions, there is a paucity in data investigating their expressions in IBS. Our aim was to evaluate colonic mucosal eosinophilia and immunohistochemical expression of COX-2 and NF-kB in patients with irritable bowel syndrome.

METHODS

A total of 80 patients who met the inclusion criteria of IBS based on Rome IV symptoms questionnaire were subjected to abdominal ultrasound, laboratory investigations, serum immunoglobulin E (IgE) level assessment and colonoscopic examination. Immunohistochemistry was performed to detect COX-2 and NF-kB expression in colonic biopsies obtained from IBS patients.

RESULTS

Histopathological examination showed that 60 colonic biopsy specimens (75%) showed few mixed inflammatory cells ≤3 cells/ HPF, 12 biopsy specimens (15%) showed eosinophilic infiltration ≥25 eosinophils/HPF and 8 biopsy specimens (10%) showed severe lymphocytic infiltration and aggregation. Colonic eosinophilic infiltrate was significantly higher among patients presented with IBS-D subtype. Serum IgE was significantly higher among patients with colonic eosinophilic infiltrate than the others. In IBS-D patients, colonic mucosa showed positive expression of COX-2 and NF-kB in 52.1% and 81.25% of cases, respectively.

CONCLUSION

Patients with IBS -particularly IBS-D subtype- should undergo colonoscopy and biopsy to exclude underlying inflammatory pathology. Moreover, patients with positive COX-2 and NF-kB need further evaluation and follow-up.

Serum L-arginine and endogenous methylarginine concentrations predict irritable bowel syndrome in adults: A nested case-control study

BACKGROUND & AIMS: Nitric oxide, a major inhibitory nonadrenergic, noncholinergic neurotransmitter that relaxes smooth muscle, may be implicated in the pathophysiology of visceral hypersensitivity in irritable bowel syndrome (IBS). Impaired bioavailability of the nitric oxide precursor molecule L-arginine and higher concentrations of methylarginines (endogenous inhibitors of nitric oxide synthesis) are known to impair nitric oxide synthesis in numerous gastrointestinal cell types. We therefore examined serum concentrations of L-arginine and the methylarginines in a nested case-control study, to assess whether these factors are associated with adult IBS.

METHODS

Data on clinical characteristics, methylarginines, and L-arginine (measured using LC-MS/MS) were collected from a random population-based cohort of Australian adults (median age = 64 years; IQR = 60-70). Cases of IBS, defined according to Rome III criteria (N = 156), and controls (N = 332) were identified from within the cohort at the 5-year follow-up.

RESULTS

In adjusted logistic regression analyses, L-arginine, asymmetric dimethylarginine, symmetric dimethylarginine, L-arginine/asymmetric dimethylarginine ratio, and Kessler-10 psychological distress scores were significantly associated with IBS (p < 0.05). [Correction added on 18 September 2021, after first online publication: In the preceding sentence, the value (p > 0.05) has been changed to (p < 0.05)]. Similar results were found for IBS subtypes. Higher serum L-arginine concentration had the strongest association with IBS diagnosis, with an odds ratio of 9.03 for those with serum L-arginine at the 75th (84 μmol/L) versus 25th (46 μmol/L) percentile (95% CI: 5.99-13.62). L-arginine had the best discriminative ability with a bias-adjusted area under the receiver operator characteristic curve of 0.859.

CONCLUSIONS

Higher serum concentrations of L-arginine and endogenous methylarginines are strongly associated with IBS in adults.

Human Leukocyte Antigen (HLA) Haplotype Does Not Influence the Inflammatory Pattern of Duodenal Lymphocytosis Linked to Irritable Bowel Syndrome

Background and objectives: Duodenal lymphocytosis (DL) is a condition characterized by enhanced infiltration of intraepithelial lymphocytes (IELs) in the duodenal mucosa, and it can be linked to both gluten- and non-gluten-related diseases, such as irritable bowel syndrome (IBS). Materials and methods: We retrospectively selected patients with DL linked to IBS. Formalin-embedded biopsy samples of the duodenum were collected. CD3 lymphocyte immunohistochemistry was used for IELs. The real-time polymerase chain reaction was used to quantify the amount of mRNA coding for tissue transglutaminase 2 (tTG2), interferon-gamma (IFNγ), toll-like receptor 2 (TLR2), and myeloid differentiation primary response 88 (MyD88). All subjects underwent DQ2-8 haplotype analysis. Controls were represented by subjects with IBS without DL. Results: Thirty-two patients with IBS-DL were retrospectively recruited. Fourteen subjects (43.8%) had a DQ2-8 haplotype. DQ2-8 positive subjects had similar levels compared to negative ones for tTG2, IFNγ, TLR2, and MyD88. Cigarette smoke did not influence molecular expression in our study. Smokers had a statistically higher IELs count than non-smokers (54.2 ± 7.7 vs. 36.0 ± 8.8, p < 0.001). A significant, direct correlation between IELs and duodenal expression of IFNγ was found (r = 0.36, p = 0.04). Conclusions: IBS with DL showed higher expression of inflammatory markers than controls, but DQ2-8 haplotype did not seem to affect their expression. Smoking might increase IELs infiltration.

A Randomized Clinical Trial of Synbiotics in Irritable Bowel Syndrome: Dose-Dependent Effects on Gastrointestinal Symptoms and Fatigue

Background

This double-blind, randomized controlled design study aimed to assess the dose-dependent effects of synbiotics on gastrointestinal symptoms of and fatigue in irritable bowel syndrome (IBS).

Methods

Thirty subjects with IBS were randomly assigned into the following three groups and received 2 capsules a day for 8 weeks: (1) high-dose (2 capsules of synbiotics); (2) low-dose (1 capsule of synbiotics and 1 capsule of placebo); and (3) placebo (2 capsules of placebo). At baseline and 8 weeks, they completed the study questionnaires.

Results

Two subjects in the high-dose group were lost to follow-up, leaving a total of 28 patients for the analysis. After 8 weeks, abdominal discomfort, abdominal bloating, frequency of formed stool, fatigue Visual Analog Scale (VAS), and Multidimensional Fatigue Inventory were significantly different among the groups (P=0.002, 0.006, 0.007, 0.028, and 0.041, respectively, by Kruskal-Wallis test). However, only abdominal discomfort, abdominal bloating, frequency of formed stool, and fatigue VAS were significantly improved in the high-dose group compared with those in the placebo group (P=0.002, 0.003, 0.002, and 0.013, respectively) by Mann-Whitney test with Bonferroni correction. No adverse drug reactions were reported.

Conclusion

High-dose synbiotics were superior to placebo in improving bowel symptoms and fatigue of IBS patients, suggesting that synbiotic dosage plays an important role in the treatment of IBS.

Immunopathological and molecular basis of functional dyspepsia and current therapeutic approaches

INTRODUCTION

Functional dyspepsia (FD) is widespread with 20% prevalence worldwide and a significant economic burden due to health care cost and constraints on daily activities of patients. Despite extensive investigation, the underlying causes of dyspepsia in a majority of patients remain unknown. Common complaints include abdominal discomfort, pain, burning, nausea, early satiety, and bloating. Motor dysfunction of the gut was long considered a major cause, but recent investigations suggest immune-based pathophysiological and molecular events in the duodenum are more probable contributing factors. Areas Covered: Inflammatory mediators and immune cells including duodenal eosinophils, intraepithelial lymphocytes, and T-cells have been implicated in the underlying cause of disease process, as have genetic factors. In this article, we critically reviewed findings, identified gaps in knowledge and suggested future directions for further investigation to identify targets and develop better therapeutic approaches. Expert commentary: Impaired gastric accommodation, slow gastric emptying, and increased visceral sensitivity have long been thought of as main causal factors of FD. However, more recent identification of eosinophilic degranulation and recruitment of T cells that induce mild duodenal inflammation are giving rise to new insights into immune-mediated pathophysiology. These insights offer promising avenues to explore for immune-mediated therapy in the future.

Recent advances in pharmacological research on the management of irritable bowel syndrome

Irritable bowel syndrome (IBS), a common gastrointestinal (GI) disorder, is associated with various factors, including lifestyle, infection, stress, intestinal flora, and related diseases. The pharmacotherapeutic stimulation of receptors and downstream signaling pathways is effective in reducing IBS symptoms; however, it is still associated with adverse effects. Various receptors related to GI motility and visceral hypersensitivity should be considered to enhance the benefit/risk ratio of IBS treatments. This review discusses recent pharmacological advances in IBS management. Several receptors related to GI motility and abdominal pain are investigated in various angles. 5-Hydroxytryptamine (5-HT) is an important neurotransmitter that activates the colonic mucosal 5-HT₄ receptor without causing severe cardiovascular adverse effects. The clinical potential of ramosetron for diarrhea-predominant IBS has been suggested because of a lower risk of ischemic colitis than conventional 5-HT₃ receptor antagonists. Toll-like receptors (TLRs), especially TLR2 and TLR4, show a significant effect on the post-infection symptoms and lipopolysaccharide-mediated regulation of GI motility. Histamine is a well-known nitrogenous compound that regulates inflammatory responses and visceral hypersensitivity. Histamine 1 receptor-mediated sensitization of the transient receptor potential vanilloid 1 is associated with IBS. Pharmacological approaches based on these signaling pathways could be useful in the development of novel IBS treatments.

Psychological stress-induced colonic barrier dysfunction: Role of immune-mediated mechanisms

BACKGROUND

Evidence suggests that patients with irritable bowel syndrome (IBS) exhibit increases in gut permeability and alterations in tight junction (TJ) protein expression. Although psychological stress worsens IBS symptoms, the mechanisms by which stress enhances gut permeability and affects TJ protein expression remain to be determined. Here, we test the hypothesis that chronic intermittent psychological stress activates the release of proinflammatory cytokines to alter TJ proteins and promotes increased gut permeability.

METHODS

Male Fischer-344 rats were subjected to 1 hour of water avoidance stress (WAS) or SHAM stress per day for 7 days. Following the stress protocol, colonic permeability was measured via transepithelial electrical resistance (TEER) and macromolecular flux of horseradish peroxidase (HRP). In tissue isolated from rats exposed to the WAS or SHAM stress, TJ proteins claudin-2, junctional adhesion molecule-A (JAM-A) and zonula occluden-1 (ZO-1) were measured via Western blotting, histological appearance of the colonic segments was assessed via hematoxylin and eosin staining, and an inflammatory cytokine panel was quantified via quantitative reverse transcription-polymerase chain reaction.

KEY RESULTS

Repetitive daily exposure to WAS decreased the TEER, increased the macromolecular flux of HRP, and altered the expression of claudin-2, JAM-A and ZO-1 proteins within colonic tissue compared to SHAM controls. In the absence of a histologically defined inflammation, the cytokine profiles of WAS-treated animals revealed an increase in interleukin-1β and tumor necrosis factor (TNF)-α. Subsequent analysis revealed a significant positive correlation between TNF-α and expression of TJ protein claudin-2.

CONCLUSIONS & INFERENCES

Our findings suggest that chronic stress increases colonic permeability via sub-inflammatory cytokine-mediated remodeling of TJ protein expression.

Lymphocytic duodenitis or microscopic enteritis and gluten-related conditions: what needs to be explored?

Microscopic enteritis (ME) is characterized by abnormal infiltration of intraepithelial lymphocytes in intestinal mucosa. It was described as duodenal lymphocytosis or lymphocytic duodenitis until the dedicated Consensus Conference of 2015. ME represents a common feature of several gluten-mediated and non-gluten related diseases; therefore, it is an umbrella term embracing several conditions. The most frequent causes of ME are gluten-related disorders (celiac disease, non-celiac gluten sensitivity, wheat allergy), Helicobacter pylori infection and drug-related damages. Less frequently, ME may be secondary to inflammatory bowel disease, some autoimmune conditions, immunoglobulin deficiencies, blood malignancies, infections and irritable bowel syndrome. Therefore, the differential diagnosis of ME may be challenging. The diagnosis of ME needs to be driven by predominant symptoms and patient history. However, it is often difficult to achieve an immediate identification of the underlying condition, and a broad variety of diagnostic tests may be required. Ultimately, long-term surveillance is needed for a final diagnosis in many cases, since a hidden or quiescent condition may be disclosed after a period of latency. In any case, strict collaboration between the clinician and the pathologist is pivotal. The treatment of ME should be personalized, depending on the underlying disease. For gluten-related conditions (celiac disease, gluten sensitivity, wheat allergy, dermatitis herpetiformis), a gluten-free diet may be proposed. For other conditions, a targeted etiologic treatment is necessary. In conclusion, ME represents a novel entity that is attracting increasing interest. The growing epidemiologic trend confirms that it will become a common condition in clinical practice.

The Colonic Tissue Levels of TLR2, TLR4 and Nitric Oxide in Patients with Irritable Bowel Syndrome

Objective Irritable bowel syndrome (IBS) is a highly prevalent and debilitating functional disorder. The toll-like receptors (TLRs) are a family of pathogen-recognition receptors in the innate immune system. In the present study we aimed to investigate the TLR2, TLR4 and nitric oxide (NO) levels in patients with IBS. Methods Fifty-one IBS patients and 15 healthy controls were included in the present study. Colonic tissue levels of TLR2, TLR4 and NO were detected using an enzyme-linked immunosorbent assays (ELISA) and through biochemical methods. Results The colonic tissue levels of TLR4 and NO were significantly higher in IBS patients than in healthy controls. A subgroup analysis, which was based on the presence of diarrhea and constipation, showed that TLR2 levels were significantly higher among individuals with diarrhea-predominant IBS than among constipation-predominant IBS patients and healthy controls. The TLR4 levels were significantly higher in the diarrhea-predominant IBS patients and constipation-predominant IBS patients than in comparison healthy controls. The colonic tissue levels of NO were higher in the constipation-predominant IBS patients than in the diarrhea-predominant IBS patients and healthy controls. Conclusion In the present study we found that the colonic tissue levels of TLR and NO were elevated in IBS patients. Our results support the presence of a degree of immune dysregulation and oxidative stress in patients with IBS.

Colorectal distention induces acute and delayed visceral hypersensitivity: role of peripheral corticotropin-releasing factor and interleukin-1 in rats

BACKGROUND

Most studies evaluating visceral sensation measure visceromotor response (VMR) to colorectal distention (CRD). However, CRD itself induces visceral sensitization, and little is known about the detailed characteristics of this response. The present study tried to clarify this question.

METHODS

VMR was determined by measuring abdominal muscle contractions as a response to CRD in rats. The CRD set consisted of two isobaric distentions (60 mmHg for 10 min twice, with a 30-min rest), and the CRD set was performed on two separate days, i.e., days 1 and 3, 8.

RESULTS

On day 1, VMR to the second CRD was increased as compared with that to the first CRD, which is the acute sensitization. VMR to the first CRD on day 3 returned to the same level as that to the first CRD on day 1, and total VMR, i.e., the whole response to the CRD set, was not different between day 1 and day 3. However, total VMR was significantly increased on day 8 as compared with that on day 1, suggesting CRD induced the delayed sensitization. Intraperitoneally administered astressin (200 µg/kg), a corticotropin-releasing factor receptor antagonist, at the end of the first CRD blocked the acute sensitization, but anakinra (20 mg/kg, intraperitoneally), an interleukin-1 receptor antagonist, did not modify it. Astressin (200 µg/kg, twice before CRD on day 8) did not alter the delayed sensitization, but anakinra (20 mg/kg, twice) abolished it.

CONCLUSIONS

CRD induced both acute sensitization and delayed sensitization, which were mediated through peripheral corticotropin-releasing factor and interleukin-1 pathways, respectively.

Effects of 12 weeks of probiotic supplementation on quality of life in colorectal cancer survivors: a double-blind, randomized, placebo-controlled trial

BACKGROUND

Probiotics may help resolve bowel symptoms and improve quality of life. We investigated the effects of 12 weeks of probiotics administration in colorectal cancer patients.

METHODS

We conducted a double-blind, randomized, placebo-controlled trial. The participants took probiotics (Lacidofil) or placebo twice a day for 12 weeks. The cancer-related quality of life (FACT), patient's health-9 (PHQ-9), and bowel symptom questionnaires were completed by each participant.

RESULTS

We obtained data for 32 participants in the placebo group and 28 participants in the probiotics group. The mean ages of total participants were 56.18 ± .86 years and 58.3% were male. Administration of probiotics significantly decreased the proportion of patients suffering from irritable bowel symptoms (0 week vs. 12 week; 67.9% vs. 45.7%, p=0.03), improved colorectal cancer-related FACT (baseline vs. 12 weeks: 19.79 ± 4.66 vs. 21.18 ± 3.67, p=0.04) and fatigue-related FACT (baseline vs. 12 weeks: 43.00 (36.50-45.50) vs. 44.50 (38.50-49.00), p=0.02) and PHQ-9 scores (0 weeks vs. 12 weeks; 3.00 (0-8.00) vs. 1.00 (0-3.00), p=0.01). We found significant differences in changes of the proportion of patients with bowel symptoms (p<0.05), functional well-being scores (p=0.04) and cancer-related FACT scores (p=0.04) between the two groups.

CONCLUSION

Probiotics improved bowel symptoms and quality of life in colorectal cancer survivors.

The Expression of Serum Antibodies Against Gonadotropin-releasing Hormone (GnRH1), Progonadoliberin-2, Luteinizing Hormone (LH), and Related Receptors in Patients with Gastrointestinal Dysfunction or Diabetes Mellitus

Gonadotropin-releasing hormone (GnRH) 1 and 2 and luteinizing hormone (LH) receptors have been described in the gastrointestinal tract. We have previously demonstrated antibodies in serum against GnRH1 in patients with gastrointestinal dysfunction and diabetes mellitus, and antibodies against GnRH receptor, LH, and LH receptor in patients with infertility. The aim of this study was to search for the expression of serum antibodies against GnRH1 with an improved enzyme-linked immune sorbent assay (ELISA), and antibodies against progonadoliberin-2, GnRH2, GnRH receptor, LH, and LH receptor with newly developed ELISAs, in patients with gastrointestinal dysfunction or diabetes mellitus. Healthy blood donors served as controls. Medical records were scrutinized. Our conclusion was that IgM antibodies against GnRH1, progonadoliberin-2, and/or GnRH receptors were more prevalent in patients with functional gastrointestinal disorders, gastrointestinal dysmotility, and/or diabetes mellitus, whereas IgG antibodies against these peptides, and LH- and LH receptor antibodies, were expressed in the same magnitude as in controls.

Intestinal microbiota and immune function in the pathogenesis of irritable bowel syndrome

The pathophysiology of irritable bowel syndrome (IBS) is believed to involve alterations in the brain-gut axis; however, the etiological triggers and mechanisms by which these changes lead to symptoms of IBS remain poorly understood. Although IBS is often considered a condition without an identified "organic" etiology, emerging evidence suggests that alterations in the gastrointestinal microbiota and altered immune function may play a role in the pathogenesis of the disorder. These recent data suggest a plausible model in which changes in the intestinal microbiota and activation of the enteric immune system may impinge upon the brain-gut axis, causing the alterations in gastrointestinal function and the clinical symptoms observed in patients with IBS. This review summarizes the current evidence for altered intestinal microbiota and immune function in IBS. It discusses the potential etiological role of these factors, suggests an updated conceptual model for the pathogenesis of the disorder, and identifies areas for future research.

Probiotics VSL#3 protect against development of visceral pain in murine model of irritable bowel syndrome

BACKGROUND AND AIMS

Irritable bowel syndrome (IBS) is linked to post-inflammatory and stress-correlated factors that cause changes in the perception of visceral events. Probiotic bacteria may be effective in treating IBS symptoms. Here, we have investigated whether early life administration of VSL#3, a mixture of 8 probiotic bacteria strains, protects against development of visceral hypersensitivity driven by neonatal maternal separation (NMS), a rat model of IBS.

METHODS

Male NMS pups were treated orally with placebo or VSL#3 from days 3 to 60, while normal, not separated rats were used as controls. After 60 days from birth, perception of painful sensation induced by colorectal distension (CRD) was measured by assessing the abdominal withdrawal reflex (score 0-4). The colonic gene expression was assessed by using the Agilent Whole Rat Genome Oligo Microarrays platform and confirmed by real time PCR.

RESULTS

NMS rats exhibited both hyperalgesia and allodynia when compared to control rats. VSL#3 had a potent analgesic effect on CRD-induced pain without changing the colorectal compliance. The microarray analysis demonstrated that NMS induces a robust change in the expression of subsets of genes (CCL2, NOS3, THP1, NTRK1, CCR2, BDRKRB1, IL-10, TNFRSF1B, TRPV4, CNR1 and OPRL1) involved in pain transmission and inflammation. TPH1, tryptophan hydroxylase 1, a validated target gene in IBS treatment, was markedly upregulated by NMS and this effect was reversed by VSL#3 intervention.

CONCLUSIONS

Early life administration of VSL#3 reduces visceral pain perception in a model of IBS and resets colonic expression of subsets of genes mediating pain and inflammation.

TRANSCRIPT PROFILING

Accession number of repository for expression microarray data is GSE38942 (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE38942).

The Gut's Little Brain in Control of Intestinal Immunity

The gut immune system shares many mediators and receptors with the autonomic nervous system. Good examples thereof are the parasympathetic (vagal) and sympathetic neurotransmitters, for which many immune cell types in a gut context express receptors or enzymes required for their synthesis. For some of these the relevance for immune regulation has been recently defined. Earlier and more recent studies in neuroscience and immunology have indicated the anatomical and cellular basis for bidirectional interactions between the nervous and immune systems. Sympathetic immune modulation is well described earlier, and in the last decade the parasympathetic vagal nerve has been put forward as an integral part of an immune regulation network via its release of Ach, a system coined "the cholinergic anti-inflammatory reflex." A prototypical example is the inflammatory reflex, comprised of an afferent arm that senses inflammation and an efferent arm: the cholinergic anti-inflammatory pathway, that inhibits innate immune responses. In this paper, the current understanding of how innate mucosal immunity can be influenced by the neuronal system is summarized, and cell types and receptors involved in this interaction will be highlighted. Focus will be given on the direct neuronal regulatory mechanisms, as well as current advances regarding the role of microbes in modulating communication in the gut-brain axis.

Stress and gene expression of individuals with chronic abdominal pain

BACKGROUND

Research examining the role of stress in gastrointestinal (GI) symptoms such as chronic abdominal pain (CAP) is controversial. The purpose of this study was to examine the expression of genes involved in metabolic stress and toxicity in men and women with high and low levels of perceived stress with and without CAP.

METHODS

Data and samples were collected and the expression of genes involved in metabolic stress and toxicity was analyzed in 26 individuals who had consented to participate in a natural history protocol. Subjects completed the 10-item Perceived Stress scale (PSS). Fasting participants' peripheral whole blood was collected for proteomic and genomic studies. Polymerase chain reaction (PCR) array was used to analyze the expression of 84 key genes involved in human stress and toxicity plus 5 housekeeping genes. Plasma interleukin-1 alpha (IL-1α) protein was quantified via enzyme-linked immunosorbent assay (ELISA).

RESULTS

Interleukin-1 alpha gene (IL1A) was upregulated in females with high stress versus females with low stress by 2.58-fold (95% CI [0.88, 4.28]). IL1A was upregulated in participants with high stress and CAP versus those with low stress and CAP by 3.47-fold (95% CI [1.14, 5.80]).

CONCLUSIONS

An upregulation of the gene coding the pro-inflammatory cytokine IL-1α suggests that the mechanism behind stress-related changes in GI symptoms is pro-inflammatory in nature. The results of this study contribute to the knowledge of the mechanism behind stress-related CAP symptoms and gender differences associated with these disorders.

Submucous rather than myenteric neurons are activated by mucosal biopsy supernatants from irritable bowel syndrome patients

BACKGROUND

We previously showed that colonic mucosal biopsy supernatants from patients with irritable bowel syndrome (IBS) activate neurons of the human submucous plexus, an area with densely packed immune cells. Based on the concept that mucosa-nerve signaling is altered in IBS, we tested in this study whether the nerve sensitizing effect of IBS mucosal biopsy supernatants is more prominent in the submucous than myenteric plexus.

METHODS

Fast neuroimaging with the voltage-sensitive dye Di-8-ANEPPS was used to record activity of guinea-pig submucous and myenteric neurons after application of constipation (C)- and diarrhea (D)-IBS supernatants (three each) and four supernatants from healthy control subjects. Results are based on recordings from 4731 neurons.

KEY RESULTS

Control supernatants did not evoke significant responses in submucous or myenteric neurons. In contrast, all IBS supernatants evoked a significant spike discharge (median 3.6 Hz) in 46% of submucous neurons. This activation was significantly stronger than in the myenteric plexus where even twice the amount of supernatants evoked a lower spike frequency (median 2.1Hz) in only 8.5% of neurons. Pharmacological studies revealed serotonin, histamine, and proteases as components mediating neuronal activation. Individual application of these components revealed that only serotonin evoked a significantly stronger activation of submucous compared with myenteric neurons.

CONCLUSIONS & INFERENCES

Direct neuronal activation by IBS mucosal biopsy supernatants is primarily a feature of submucous rather than myenteric neurons. This is associated with a stronger excitation of submucous neurons by serotonin. The plexus-specific effects support the concept that altered mucosa-nerve signaling underlies disturbances in IBS.

Irritable bowel syndrome and the elusive mast cells

Irritable bowel syndrome (IBS) is the most common condition seen by gastroenterologists. It presents with alternating symptoms of bowel dysfunction that often worsens with stress. The cause of these symptoms eludes investigators and many attempts have been made to discover an underlying pathology. This is a daunting task since symptoms come and go, and change characteristics. Furthermore, the pathology of IBS is unlikely to be identical in all patients. In addition, all symptoms and all features studied thus far have a strong overlap with healthy volunteers. Elsewhere in this issue, Braak et al. report a well-designed clinical investigation in patients with IBS and come to the conclusion that IBS is not characterized by mast cell or other immune cell proliferation, but by immune dysregulation in the colon. Is this the final answer?

Immunoinflammation and functional gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) are a group of conditions characterized by the dysfunction of the gastrointestinal (GI) tract. Although the specific pathogenesis of FGIDs is unclear, several theories have been proposed to explain the symptoms. Abnormal GI motility and visceral hypersensitivity have always been considered to be the main physiopathologic basis of FGIDs, and FGIDs related to psychomental disorders have also caused a major social concern. In recent years, a growing number of researches have proved that cytokines have a significant influence on GI motility, and the role of cytokines in FGIDs has aroused more and more attention. In this article, we discuss the interaction between immunoinflammation and FGIDs, and make an overview of current studies.

Pro-inflammatory chemokine C-C motif ligand 16 (CCL-16) dysregulation in irritable bowel syndrome (IBS): a pilot study

BACKGROUND

Irritable bowel syndrome (IBS) is a serious health problem that affects an estimated 10-15% of people worldwide and has economic consequences in the United States of over $30 billion annually. In the US, IBS affects all races and both sexes, with more females than males (2:1) reporting symptoms consistent with IBS. Although the etiology of this functional gastrointestinal disorder is unknown, literature suggests that a subclinical inflammatory component has a role in the etiologic mechanisms underlying IBS. The aim of this study was to evaluate the gene expression of inflammatory biomarkers in patients with and without IBS and among different IBS phenotypes.

METHODS

Irritable bowel syndrome patients (n=12) that met Rome III Criteria for IBS longer than 6months were compared with healthy matched controls (n=12). Peripheral whole blood from fasting participants was collected and RNA was extracted. The expression of 96 inflammatory genes was then analyzed using a custom quantitative real-time PCR array.

KEY RESULTS

CCL-16 gene expression was upregulated by 7.46-fold in IBS patients when compared with controls. CCL-16 was overexpressed by over 130-fold in IBS-constipation patients when compared with both controls and IBS-diarrhea patients.

CONCLUSIONS & INFERENCES

These results further suggest a subclinical inflammatory component underlying IBS. To better understand the phenotypic differences in IBS it is important to broaden the study of these inflammatory and other biomarkers.

Risk factors for chronic cerebrospinal venous insufficiency (CCSVI) in a large cohort of volunteers

Background

The role of intra- and extra-cranial venous system impairment in the pathogenesis of various vascular, inflammatory and neurodegenerative neurological disorders, as well as in aging, has not been studied in detail. Nor have risk factors been determined for increased susceptibility of venous pathology in the intra-cranial and extra-cranial veins. The aim of this study was to investigate the association between presence of a newly proposed vascular condition called chronic cerebrospinal venous insufficiency (CCSVI) and environmental factors in a large volunteer control group without known central nervous system pathology.

Methods and Findings

The data were collected in a prospective study from 252 subjects who were screened for medical history as part of the entry criteria and participated in the case-control study of CCSVI prevalence in multiple sclerosis (MS) patients, and then were analyzed post-hoc. All participants underwent physical and Doppler sonography examinations, and were assessed with a structured environmental questionnaire. Fullfilment of ≥2 positive venous hemodynamic (VH) criteria on Doppler sonography was considered indicative of CCSVI diagnosis. Risk and protective factors associated with CCSVI were analyzed using logistic regression analysis. Seventy (27.8%) subjects presented with CCSVI diagnosis and 153 (60.7%) presented with one or more VH criteria. The presence of heart disease (p = .001), especially heart murmurs (p = .007), a history of infectious mononucleosis (p = .002), and irritable bowel syndrome (p = .005) were associated with more frequent CCSVI diagnosis. Current or previous smoking (p = .029) showed a trend for association with more frequent CCSVI diagnosis, while use of dietary supplements (p = .018) showed a trend for association with less frequent CCSVI diagnosis.

Conclusions

Risk factors for CCSVI differ from established risk factors for peripheral venous diseases. Vascular, infectious and inflammatory factors were associated with higher CCSVI frequency.

Patients with irritable bowel syndrome and dysmotility express antibodies against gonadotropin-releasing hormone in serum

BACKGROUND

The etiology of irritable bowel syndrome (IBS) and dysmotility is in most cases unknown. Organic, pathognomonic changes have not been described. We have previously demonstrated sporadic expressions of antibodies against gonadotropin-releasing hormone (GnRH) in serum from these patients. The aim of this study was to screen for the presence of GnRH antibodies in healthy subjects and patients with gastrointestinal (GI) diseases.

METHODS

Consecutive patients suffering from either IBS, idiopathic dysmotility, GI complaints secondary to diabetes mellitus, celiac disease or inflammatory bowel disease (IBD) were included. Healthy blood donors served as controls. Blood samples were taken for analyzing IgM and IgG antibodies against GnRH using an ELISA method. Medical records were scrutinized with respect to duration of symptoms, co-existing diseases, drug treatments, hereditary factors, and laboratory analyses.

KEY RESULTS

Healthy controls expressed low levels of GnRH IgM antibodies in a prevalence of 23%. The prevalence of GnRH IgM antibodies in IBS and dysmotility patients was 42% (P = 0.008), and the levels were higher (P = 0.000). Patients with diabetes mellitus expressed GnRH IgM antibodies in the same prevalence as controls (25%), but in higher levels (P = 0.02). Patients with celiac disease or IBD had the same or lower levels of antibodies. There were no associations between antibodies, other co-existing diseases or laboratory analyses.

CONCLUSIONS & INFERENCES

Higher levels of GnRH IgM antibodies were detected in patients with IBS and dysmotility, but not organic GI diseases, compared with healthy controls. These findings suggest that IBS and dysmotility to some extent may be of an autoimmune origin.

Fecal assays detect hypersensitivity to cow's milk protein and gluten in adults with irritable bowel syndrome

BACKGROUND & AIMS

Some patients with irritable bowel syndrome (IBS)-like symptoms suffer from food hypersensitivity (FH); their symptoms improve when they are placed on elimination diets. No assays identify patients with FH with satisfactory levels of sensitivity. We determined the frequency of FH among patients with symptoms of IBS and the ability of fecal assays for tryptase, eosinophil cationic protein (ECP), or calprotectin to diagnose FH.

METHODS

The study included 160 patients with IBS, 40 patients with other gastrointestinal diseases, and 50 healthy individuals (controls). At the start of the study, patients completed a symptom severity questionnaire, fecal samples were assayed, and levels of specific immunoglobulin E were measured. Patients were observed for 4 weeks, placed on an elimination diet (without cow's milk and derivatives, wheat, egg, tomato, and chocolate) for 4 weeks, and kept a diet diary. Those who reported improvements after the elimination diet period were then diagnosed with FH, based on the results of a double-blind, placebo-controlled, oral food challenge (with cow's milk proteins and then with wheat proteins).

RESULTS

Forty of the patients with IBS (25%) were found to have FH. Levels of fecal ECP and tryptase were significantly higher among patients with IBS and FH than those without FH. The ECP assay was the most accurate assay for diagnosis of FH, showing 65% sensitivity and 91% specificity.

CONCLUSIONS

Twenty-five percent of patients with IBS have FH. These patients had increased levels of fecal ECP and tryptase, indicating that they might cause inflammation in patients with IBS. Fecal assays for ECP could be used to identify FH in patients with IBS.

The role of eosinophils and mast cells in intestinal functional disease

Functional gastrointestinal disorders (FGIDs) are common and currently defined by a symptom-based classification with no discernable pathology. In functional dyspepsia (FD), the duodenum is now implicated as a key area where symptoms originate.This is attributed to immune activation with increasing evidence indicating a role for duodenal eosinophilia. In irritable bowel syndrome (IBS), mastocytosis has been documented throughout the small and large intestine. Eosinophils and mast cells are an important link between innate and adaptive immunity, and are important in allergic type TH2 inflammation. Eosinophils may give rise to symptoms due to release of preformed cytokine proteins, which trigger neural excitation, muscle spasm, and pain. The close relationship of mast cells to nerves in IBS may similarly give rise to symptoms. Genetic studies also support of the role of innate immunity in FGIDs. The data supporting a prime role for eosinophils and mast cells in subsets of FD and IBS has become credible, and these data should be used to implement advances in diagnosis and therapeutic trials.

Inflammation, immunity and functional gastrointestinal disorders

The pathogenesis of functional gastrointestinal disorders (FGIDs) is closely related to psychological factors. Mucosal immunity and inflammation are causes of gastrointestinal symptoms in patients with FGIDs. Inflammation factors not only play an important role in the development of depression but also have an impact on gastrointestinal motility. The role of immune mechanisms in the pathogenesis of FGIDs has also attracted wide attention. In this article, we will review the roles of inflammation and immunity in the pathogenesis of FGIDs.

Mast cells as cellular sensors in inflammation and immunity

Mast cells are localized in tissues. Intense research on these cells over the years has demonstrated their role as effector cells in the maintenance of tissue integrity following injury produced by infectious agents, toxins, metabolic states, etc. After stimulation they release a sophisticated array of inflammatory mediators, cytokines, and growth factors to orchestrate an inflammatory response. These mediators can directly initiate tissue responses on resident cells, but they have also been shown to regulate other infiltrating immune cell functions. Research in recent years has revealed that the outcome of mast cell actions is not always detrimental for the host but can also limit disease development. In addition, mast cell functions highly depend on the physiological context in the organism. Depending on the genetic background, strength of the injurious event, the particular microenvironment, mast cells direct responses ranging from pro- to anti-inflammatory. It appears that they have evolved as cellular sensors to discern their environment in order to initiate an appropriate physiological response either aimed to favor inflammation for repair or at the contrary limit the inflammatory process to prevent further damage. Like every sophisticated machinery, its dysregulation leads to pathology. Given the broad distribution of mast cells in tissues this also explains their implication in many inflammatory diseases.

Low-grade inflammation plays a pivotal role in gastrointestinal dysfunction in irritable bowel syndrome

The pathogenesis of irritable bowel syndrome (IBS) is considered to be multifactorial and includes psychosocial factors, visceral hypersensitivity, infection, microbiota and immune activation. It is becoming increasingly clear that low-grade inflammation is present in IBS patients and a number of biomarkers have emerged. This review describes the evidence for low-grade inflammation in IBS and explores its mechanism with particular focus on gastrointestinal motor dysfunction. Understanding of the immunological basis of the altered gastrointestinal motor function in IBS may lead to new therapeutic strategies for IBS.

Normal quantity and distribution of mast cells and eosinophils in the pediatric colon

The normal number and distribution of mast cells (MCs) and eosinophils in colonic mucosa are largely unknown. Accordingly, we examined colonic biopsies obtained during endoscopic examinations of pediatric patients. The study included 41 patients (21 males and 20 females). The mean age was 11.72 years (range 3.3-19.7 years). Patients were followed for a mean time of 23.4 months (range 12-50 months). Our results showed a gradual decrease in the number of eosinophils in the lamina propria from the cecum to the descending colon (14.2 ± 6.1 and 10.7 ± 5.6 eosinophils//high-power field [hpf], respectively), with another peak in the rectosigmoid (12.4 ± 6.1 eosinophils/hpf). Eosinophils within the surface and crypt epithelium were more commonly encountered in the cecum and the rectosigmoid. Eosinophils clusters were rare but were more frequently found in the cecum and rectosigmoid. The largest number of MCs was observed in the descending colon and the lowest in the rectosigmoid (17.56 ± 7.28 and 14.5 ± 6.35 MCs/hpf, respectively). No MCs were identified within the surface epithelium. Very rare MCs were observed within the crypt epithelium, with the highest number observed in the cecum (0.34 ± 0.53 MCs/hpf) and the lowest number observed in the descending colon (0.02 ± 0.16 MCs/hpf). More MCs were present in the cecum and descending colon of females vs males (P  =  0.02 and 0.04, respectively). Our results establish baseline gastrointestinal eosinophils and MC counts in various parts of the pediatric colon.

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.

Questioning the bacterial overgrowth hypothesis of irritable bowel syndrome: an epidemiologic and evolutionary perspective

Although studies indicate that small intestinal bacterial overgrowth (SIBO) is prevalent in irritable bowel syndrome (IBS), it remains unclear whether SIBO causes IBS. This review presents an epidemiologic and evolutionary inquiry that questions the bacterial overgrowth hypothesis of IBS, as follows. (1) Although the hypothesis may be biologically plausible, there is also a strong rationale for competing hypotheses; it is unlikely that SIBO is the predominant cause of IBS in all comers, because competing explanations are sensible and defensible. Moreover, data indicate that the test used to promulgate the SIBO hypothesis - the lactulose hydrogen breath test - may not have measured SIBO in the first place. (2) We do not have evidence of SIBO being absent before IBS symptoms, and present after IBS emerges. (3) There is not a dose-response relationship between small intestinal microbiota and IBS symptoms. (4) The relationship between SIBO and IBS is highly inconsistent among studies. (5) Many effective IBS therapies do not address SIBO at all, yet have a more favorable "number needed to treat" than antibiotics. (6) IBS does not behave like a traditional infectious disease, suggesting that microbes may not principally cause the syndrome. (7) Other factors may confound the relationship between SIBO and IBS, including proton pump inhibitors. (8) Whereas the brain-gut hypothesis is evolutionary sensible, the bacterial hypothesis is harder to defend from an evolutionary perspective. The article concludes that bacteria may contribute to some IBS symptoms, but that bacteria cannot be the only explanation, and a causal link between SIBO and IBS is not secure.

Systematic review of animal models of post-infectious/post-inflammatory irritable bowel syndrome

AIMS

Post-infectious irritable bowel syndrome (PI-IBS) is a subset of IBS which occurs after an episode of acute gastrointestinal infections. The mechanisms of PI-IBS are not fully understood. Currently, numerous animal models have been used in the study of PI-IBS. This article reviews the strengths and weaknesses of these models.

METHODS

All relevant articles were identified by searching in Ovid SP from 1962, the year the term PI-IBS was coined, up to December 31, 2009. The types of model were categorized as either post-infectious or post-inflammatory, and the characteristics of each kind of model were listed.

RESULTS

Based on our literature search, 268 articles were identified. Of those articles, 50 were included in this review. The existing PI-IBS models include infection with bacteria (e.g., Campylobacter jejuni, Salmonella enterica, and Campylobacter rodentium), and infection with parasites (e.g., Trichinella spiralis, Nippostrongylus brasiliensis, and Cryptosporidium parvum). The post-inflammatory IBS models are commonly induced with chemical agents, such as acetic acid, deoxycholic acid, dextran sulfate sodium, mustard oil, zymosan, and trinitrobenzene sulfonic acid (TNBS). TNBS is the most commonly used agent for post-inflammatory IBS models, but the experimental protocol varies. These models have one or more aspects similar to IBS patients.

CONCLUSIONS

Different methods have been used for the development of post-infectious or post-inflammatory IBS models. Each model has its weaknesses and strengths. More studies are needed to establish post-infection IBS models using more common pathogens. A standard protocol in developing TNBS-induced post-inflammatory IBS model is needed.

Differential expression of toll-like receptors in patients with irritable bowel syndrome

OBJECTIVES

The pathogenesis of irritable bowel syndrome (IBS) is poorly understood. One contributory factor may be low-grade mucosal inflammation, perhaps initiated by the microbiota. Toll-like receptors (TLRs) are a family of pathogen-recognition receptors of the innate immune system. The aim of this study was to evaluate the potential involvement of TLRs in IBS to further understand the involvement of the innate immune system in this complex disorder.

METHODS

The expression of TLRs was investigated in colonic biopsy samples obtained from 26 IBS patients and compared with 19 healthy controls. Protein expression of TLR4, TLR7, and TLR8 was confirmed by immunofluorescence and alterations in the TLR4 protein were confirmed by western blot.

RESULTS

Quantitative reverse transcriptase-PCR showed increased levels of TLR4 (P≤0.001) and TLR5 (P=0.0013) and decreased levels of TLR7 (P≤0.001) and TLR8 (P=0.0019) in IBS patients.

CONCLUSIONS

Our results support the presence of an immune engagement between the microbiota and the host in IBS; an interaction that involves innate immunity and could generate a low-grade inflammatory response. These findings could also offer an additional biomarker of the disease or a disease subset.

Anorectal function and visceral hypersensitivity in celiac disease

OBJECTIVE

To evaluate anorectal function and rectal sensitivity thresholds in patients with celiac disease (CD).

METHODS

In 25 unselected patients with CD (16 female, 9 male; mean age 45, range 24 to 75 y) and 20 controls (12 female, 8 male; mean age 41, range 20 to 65 y) anorectal manometry and rectal balloon distension test were conducted using a 4 lumen water perfused catheter with a polyethylene balloon (Zinectics Manometric Catheter, Medtronic).

RESULTS

In celiac patients the maximal anal resting pressure, reflecting the internal anal sphincter function, was significantly higher than that in the controls: 87.8±21.7 mm Hg versus 66.7±15.2 mm Hg (P<0.001). There were no considerable differences between both the groups neither in the maximal anal squeeze nor in the cough pressures. Celiac patients had significantly lower first sensation threshold: 25.6±10.8 mL versus 37.5±12.5 mL (P<0.05). Visceral hypersensitivity (rectal pain/discomfort threshold ≤100 mL) was observed in 36% of celiac patients and in none of the controls (P<0.01).

CONCLUSIONS

The increased anal resting pressure and rectal hypersensitivity are observed in CD. Disturbances in gastrointestinal motility and visceral perception in the course of CD may occur at different levels of the brain-gut axis including direct changes in the enteric nervous system.

The association of mast cells and serotonin in children with chronic abdominal pain of unknown etiology

Background

Abdominal pain of unknown origin affects up to 20% of school-aged children. Evaluation of children is symptom-based without clear guidelines to investigate molecular mechanisms of abdominal pain. Aberrant molecular mechanisms may increase intestinal permeability leading to interactions between the immune and nervous systems, subclinical inflammation, and visceral pain. This study evaluated the association between interleukin-6 (IL-6), mast cell infiltrates, and serotonin (5-HT) levels in gastrointestinal (GI) biopsies, with perceived abdominal pain in a pediatric cohort.

Methods

Clinical data and biopsy samples from pediatric patients (n = 48) with chronic abdominal pain, with and without inflammation were included. Formalin-fixed paraffin-embedded GI biopsies were sectioned and immunohistochemistry performed for IL-6 and 5-HT; mast cells were identified with toluidine blue stain. Histological findings were compared to self-reported abdominal pain between groups.

Results

There was significantly greater IL-6 immunoreactivity in biopsies with confirmed histologic inflammation (p = 0.004). There was a greater number of mast cells per HPF in non-inflammatory biopsies (3.5 ± 2.9) compared to the inflammatory biopsies (2.6 ± 1.8) p = 0.049. The non-inflammatory biopsy group was significantly less likely to respond to standard treatment as evidenced by higher pain reports (p = .018). Mast cells (p = .022) and 5-HT (p = .02) were significantly related to abdominal pain scores.

Conclusions

A potential association between self-reported abdominal pain, number of mast cells, and 5-HT levels, which may contribute to perceived GI pain in pediatric patients may exist.

Chemo-nociceptive signalling from the colon is enhanced by mild colitis and blocked by inhibition of transient receptor potential ankyrin 1 channels

BACKGROUND AND PURPOSE

Transient receptor potential ankyrin 1 (TRPA1) channels are expressed by primary afferent neurones and activated by irritant chemicals including allyl isothiocyanate (AITC). Here we investigated whether intracolonic AITC causes afferent input to the spinal cord and whether this response is modified by mild colitis, morphine or a TRPA1 channel blocker.

EXPERIMENTAL APPROACH

One hour after intracolonic administration of AITC to female mice, afferent signalling was visualized by expression of c-Fos in laminae I-II(o) of the spinal dorsal horn at sacral segment S1. Mild colitis was induced by dextran sulphate sodium (DSS) added to drinking water for 1 week.

KEY RESULTS

Relative to vehicle, AITC (2%) increased expression of c-Fos in the spinal cord. Following induction of mild colitis by DSS (2%), spinal c-Fos responses to AITC, but not vehicle, were augmented by 41%. Colonic inflammation was present (increased myeloperoxidase content and disease activity score), whereas colonic histology, locomotion, feeding and drinking remained unchanged. Morphine (10 mg.kg(-1)) or the TRPA1 channel blocker HC-030031 (300 mg.kg(-1)) inhibited the spinal c-Fos response to AITC, in control and DSS-pretreated animals, whereas the response to intracolonic capsaicin (5%) was blocked by morphine but not HC-030031.

CONCLUSIONS AND IMPLICATIONS

Activation of colonic TRPA1 channels is signalled to the spinal cord. Mild colitis enhanced this afferent input that, as it is sensitive to morphine, is most likely of a chemonociceptive nature. As several irritant chemicals can be present in chyme, TRPA1 channels may mediate several gastrointestinal pain conditions.

Low-grade inflammation plays a pivotal role in gastrointestinal dysfunction in irritable bowel syndrome

The pathogenesis of irritable bowel syndrome (IBS) is considered to be multifactorial and includes psychosocial factors, visceral hypersensitivity, infection, microbiota and immune activation. It is becoming increasingly clear that low-grade inflammation is present in IBS patients and a number of biomarkers have emerged. This review describes the evidence for low-grade inflammation in IBS and explores its mechanism with particular focus on gastrointestinal motor dysfunction. Understanding of the immunological basis of the altered gastrointestinal motor function in IBS may lead to new therapeutic strategies for IBS.

An outbreak of acute bacterial gastroenteritis is associated with an increased incidence of irritable bowel syndrome in children

OBJECTIVES

Acute bacterial gastroenteritis is associated with subsequent post-infectious irritable bowel syndrome (PI-IBS) in adults. Less is known about this relationship in children. In May 2000, contamination of municipal water by Escherichia coli 0157:H7 and Campylobacter species caused a large outbreak of acute gastroenteritis in Walkerton, Ontario. We assessed this association among a cohort of children enrolled in the Walkerton Health Study (WHS).

METHODS

WHS participants who were under age 16 at the time of the outbreak but who reached age 16 during the 8-year study follow-up were eligible for the pediatric PI-IBS study cohort. Eligibility also required no diagnosis of IBS or inflammatory bowel disease before the outbreak and permanent residency in the Walkerton postal code at the time of the outbreak. Validated criteria were used to classify subjects as having had no gastroenteritis (unexposed controls), self-reported gastroenteritis, or clinically suspected gastroenteritis during the outbreak. From 2002 to 2008, standardized biennial interviews used a modified Bowel Disease Questionnaire to diagnose IBS by Rome I criteria. Risk factors for IBS were identified by logistic regression.

RESULTS

In all, 467 subjects were eligible for the pediatric PI-IBS study cohort (47.1% female; mean age 11.6+/-2.44 years at the time of the outbreak). Of these, 305 were exposed to GE (130 clinically suspected and 175 self-reported) and 162 were unexposed controls. The cumulative incidence of IBS was significantly increased among exposed subjects vs. controls (10.5% vs. 2.5%; odds ratio 4.6, 95% confidence interval (1.6, 13.3)). In an unadjusted risk factor analysis, IBS was associated with a shorter time interval from exposure to assessment of IBS symptoms, female gender, diarrheal illness lasting more than 7 days, weight loss >10 lb, and antibiotic use during the outbreak. In adjusted analyses, both female gender and time interval to assessment of IBS symptoms remained independent predictors of PI-IBS.

CONCLUSIONS

Acute bacterial gastroenteritis is associated with subsequent IBS in children as in adults. Risk factors for PI-IBS in children are similar to those identified among adults. Confirmation of these findings in similar cohorts is needed.

Chlamydia trachomatis antigens in enteroendocrine cells and macrophages of the small bowel in patients with severe irritable bowel syndrome

BACKGROUND

Inflammation and immune activation have repeatedly been suggested as pathogentic factors in irritable bowel syndrome (IBS). The driving force for immune activation in IBS remains unknown. The aim of our study was to find out if the obligate intracellular pathogen Chlamydia could be involved in the pathogenesis of IBS.

METHODS

We studied 65 patients (61 females) with IBS and 42 (29 females) healthy controls in which IBS had been excluded. Full thickness biopsies from the jejunum and mucosa biopsies from the duodenum and the jejunum were stained with a monoclonal antibody to Chlamydia lipopolysaccharide (LPS) and species-specific monoclonal antibodies to C. trachomatis and C. pneumoniae. We used polyclonal antibodies to chromogranin A, CD68, CD11c, and CD117 to identify enteroendocrine cells, macrophages, dendritic, and mast cells, respectively.

RESULTS

Chlamydia LPS was present in 89% of patients with IBS, but in only 14% of healthy controls (p < 0.001) and 79% of LPS-positive biopsies were also positive for C. trachomatis major outer membrane protein (MOMP). Staining for C. pneumoniae was negative in both patients and controls. Chlamydia LPS was detected in enteroendocrine cells of the mucosa in 90% of positive biopsies and in subepithelial macrophages in 69% of biopsies. Biopsies taken at different time points in 19 patients revealed persistence of Chlamydia LPS up to 11 years. The odds ratio for the association of Chlamydia LPS with presence of IBS (43.1; 95% CI: 13.2-140.7) is much higher than any previously described pathogenetic marker in IBS.

CONCLUSIONS

We found C. trachomatis antigens in enteroendocrine cells and macrophages in the small bowel mucosa of patients with IBS. Further studies are required to clarify if the presence of such antigens has a role in the pathogenesis of IBS.

Stress-related modulation of inflammation in experimental models of bowel disease and post-infectious irritable bowel syndrome: role of corticotropin-releasing factor receptors

The interaction between gut inflammatory processes and stress is gaining increasing recognition. Corticotropin-releasing factor (CRF)-receptor activation in the brain is well established as a key signaling pathway initiating the various components of the stress response including in the viscera. In addition, a local CRF signaling system has been recently established in the gut. This review summarize the present knowledge on mechanisms through which both brain and gut CRF receptors modulate intestinal inflammatory processes and its relevance towards increased inflammatory bowel disease (IBD) activity and post-infectious irritable bowel syndrome (IBS) susceptibility induced by stress.

A role for corticotropin-releasing factor in functional gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs), which include irritable bowel syndrome (IBS), encompass a heterogeneous group of diseases identified by chronic or recurrent symptom-based diagnostic criteria. Psychosocial factors are key components in the outcome of clinical manifestations of IBS symptoms. Anxiogenic and endocrine responses to stress are mediated by the corticotropin-releasing factor (CRF)-CRF1 receptor pathway. Preclinical studies show that activation of the CRF1 receptor by exogenous CRF or stress recapitulates many functional symptoms of IBS diarrhea-predominant patients as related to anxiogenic/hypervigilant behavior, autonomic nervous system alterations, induction of diarrhea, visceral hyperalgesia, enhanced colonic motility, mucus secretion, increased permeability, bacterial translocation, and mast cell activation, which are all alleviated by selective CRF1 receptor antagonists. Clinical studies also support that CRF administration can induce IBS-like symptoms in healthy subjects and heighten colonic sensitivity in IBS patients. Yet to be ascertained is whether CRF1 receptor antagonists hold promise as a new therapy in IBS treatment.

Infliximab therapy decreases the levels of TNF-alpha and IFN-gamma mRNA in colonic mucosa of ulcerative colitis

OBJECTIVE

The mechanisms of action of infliximab (IFX) in the treatment of ulcerative colitis (UC) are poorly understood. The aim of the study was to investigate the changes in tissue expression of tumor necrosis factor-alpha (TNF-alpha) and other cytokines in UC patients receiving IFX treatment.

MATERIAL AND METHODS

The levels of TNF-alpha, interleukin (IL)-10, IL-4, and interferon-gamma (IFN-gamma) mRNA in colonic biopsies from 32 UC patients during IFX treatment were measured by real-time polymerase chain reaction (PCR) and compared with those of 19 controls. Immunohistochemistry was performed to characterize the changes of inflammatory cells during treatment.

RESULTS

IFX reduced the expression of TNF-alpha and IFN-gamma mRNA, but not that of IL-10 and IL-4 mRNA. Reductions in TNF-alpha mRNA were correlated to clinical and endoscopic improvements, and normalization of TNF-alpha mRNA was obtained in patients with healed mucosa. The numbers of T lymphocytes and macrophages were significantly decreased in patients with healed mucosa after IFX treatment, although compared to normal controls, there were still increased levels of TNF-alpha-positive cells after treatment.

CONCLUSIONS

IFX induced down-regulation of the mucosal TNF-alpha and IFN-gamma mRNA expression in UC patients. The numbers of T lymphocytes and macrophages were significantly decreased in patients with endoscopically healed mucosa after IFX treatment.

Alosetron, cilansetron and tegaserod modify mesenteric but not colonic blood flow in rats

BACKGROUND AND PURPOSE

As the use of the 5-HT(3) receptor antagonist alosetron (GlaxoSmithKline) and the 5-HT(4) receptor agonist tegaserod (Novartis) in patients with irritable bowel syndrome has been associated with cases of ischaemic colitis, the effects of alosetron, cilansetron (Solvay) and tegaserod on the rat splanchnic circulation were evaluated.

EXPERIMENTAL APPROACH

Phenobarbital-anaesthetised rats were instrumented to record blood flow in the superior mesenteric artery and transverse colon and to calculate mesenteric and colonic vascular conductance.

KEY RESULTS

Intravenous alosetron (0.03-0.3 mg.kg(-1)) did not alter blood pressure or heart rate but reduced mesenteric blood flow and vascular conductance by 15-20%. This activity profile was also seen after intraduodenal alosetron and shared by the 5-HT(3) receptor antagonist cilansetron. In contrast, blood flow, vascular conductance and intraluminal pressure in the colon were not modified by alosetron and cilansetron. Intravenous or intraduodenal tegaserod (0.3-1.0 mg.kg(-1)) had no inhibitory effect on mesenteric and colonic blood flow. Peroral treatment of rats with alosetron or tegaserod for 7 days did not modify mesenteric haemodynamics at baseline and after blockade of nitric oxide synthesis. Mild inflammation induced by dextran sulphate sodium failed to provoke a vasoconstrictor effect of cilansetron in the colon.

CONCLUSIONS AND IMPLICATIONS

Alosetron and cilansetron, not tegaserod, caused a small and transient constriction of the rat mesenteric vascular bed, whereas blood flow in the colon remained unaltered. The relevance of these findings to the treatment-associated occurrence of ischaemic colitis in patients with irritable bowel syndrome remains open.

Gastrointestinal neuromuscular pathology: guidelines for histological techniques and reporting on behalf of the Gastro 2009 International Working Group

The term gastrointestinal neuromuscular disease describes a clinically heterogeneous group of disorders of children and adults in which symptoms are presumed or proven to arise as a result of neuromuscular, including interstitial cell of Cajal, dysfunction. Such disorders commonly have impaired motor activity, i.e. slowed or obstructed transit with radiological evidence of transient or persistent visceral dilatation. Whilst sensorimotor abnormalities have been demonstrated by a variety of methods in these conditions, standards for histopathological reporting remain relatively neglected. Significant differences in methodologies and expertise continue to confound the reliable delineation of normality and specificity of particular pathological changes for disease. Such issues require urgent clarification to standardize acquisition and handling of tissue specimens, interpretation of findings and make informed decisions on risk-benefit of full-thickness tissue biopsy of bowel or other diagnostic procedures. Such information will also allow increased certainty of diagnosis, facilitating factual discussion between patients and caregivers, as well as giving prognostic and therapeutic information. The following report, produced by an international working group, using established consensus methodology, presents proposed guidelines on histological techniques and reporting for adult and paediatric gastrointestinal neuromuscular pathology. The report addresses the main areas of histopathological practice as confronted by the pathologist, including suction rectal biopsy and full-thickness tissue obtained with diagnostic or therapeutic intent. For each, indications, safe acquisition of tissue, histological techniques, reporting and referral recommendations are presented.

Physiological and pathophysiological functions of intestinal mast cells

The normal gastrointestinal (GI) mucosa is equipped with mast cells that account for 2-3% of lamina propria cells under normal conditions. Mast cells are generally associated with allergic disease, and indeed, food allergy that manifests in the GI tract is usually mast cell dependent. On the other hand, mast cells have a number of physiological functions in the GI tract, namely regulatory functions such as control of blood flow and coagulation, smooth muscle contraction and peristalsis, and secretion of acid, electrolytes, and mucus by epithelial cells. One of the most intriguing functions of intestinal mast cells is their role in host defense against microbes like bacteria, viruses, or parasites. Mast cells recognize microbes by antibody-dependent mechanisms and through pattern-recognition receptors. They direct the subsequent immune response by attracting both granulocytes and lymphocytes to the site of challenge via paracrine cytokine release. Moreover, mast cells initiate, by releasing proinflammatory mediators, innate defense mechanisms such as enhanced epithelial secretion, peristalsis, and alarm programs of the enteric nervous This initiation can occur in response to a primary contact to the microbe or other danger signals, but becomes much more effective if the triggering antigen reappears and antibodies of the IgE or IgG type have been generated in the meantime by the specific immune system. Thus, mast cells operate at the interface between innate and adaptive immune responses to enhance the defense against pathogens and, most likely, the commensal flora. In this respect, it is important to note that mast cells are directly involved in controlling the function of the intestinal barrier that turned out to be a crucial site for the development of infectious and immune-mediated diseases. Hence, intestinal mast cells perform regulatory functions to maintain tissue homeostasis, they are involved in host defense mechanisms against pathogens, and they can induce allergy once they are sensitized against foreign antigens. The broad spectrum of functions makes mast cells a fascinating target for future pharmacological or nutritional interventions.

Plasticity of enteric nerve functions in the inflamed and postinflamed gut

Inflammation of the gut alters the properties of the intrinsic and extrinsic neurons that innervate it. While the mechanisms of neuroplasticity differ amongst the inflammatory models that have been used, amongst various regions of the gut, and between intrinsic vs extrinsic neurons, a number of consistent features have been observed. For example, intrinsic and extrinsic primary afferent neurons become hyperexcitable in response to inflammation, and interneuronal synaptic transmission is facilitated in the enteric circuitry. These changes contribute to alterations in gut function and sensation in the inflamed bowel as well as functional disorders, and these changes persist for weeks beyond the point at which detectable inflammation has subsided. Thus, gaining a more thorough understanding of the mechanisms responsible for inflammation-induced neuroplasticity, and strategies to reverse these changes are clinically relevant goals. The purpose of this review is to summarize our current knowledge regarding neurophysiological changes that occur during and following intestinal inflammation, and to identify and address gaps in our knowledge regarding the role of enteric neuroplasticity in inflammatory and functional gastrointestinal disorders.

Treatment of diarrhea-predominant Post-infectious irritable bowel syndrome with Deanxit: an analysis of 30 cases

AIM: To observe the effect and safety of Deanxit in combination with Birid Triple Viable (BIFICO) in treatment of diarrhea-predominant postinfectious irritable bowel syndrome (PI-IBS) without obvious psychiatric symptoms.

METHODS: Sixty cases of diarrhea-predominant PI-IBS without obvious psychiatric symptoms were divided into 2 groups, and each group had 30 cases. Combination treatment group received both Deanxit and BIFICO treatment, while the control group received BIFICO treatment only. After 2-wk treatment, the therapeutic effect and drug safety were compared between the 2 groups.

RESULTS: The total effective rate was 90.0% in combination treatment group, and 60.0% in BIFICO group. The total effective rate in combination treatment group was significantly higher than that of BIFICO group (P < 0.05). There were no obvious side-effects found in both groups.

CONCLUSION: Deanxit combined with BIFICO is safe and effective in treatment of PI-IBS without obvious psychiatric symptoms.