Infection, immune function, and functional gut disorders

The interaction between obesity and visceral hypersensitivity

Obesity has been a worldwide problem associated with numerous chronic diseases such as cardiovascular disease, type 2 diabetes, and metabolic disorders. It may also play a role in visceral hypersensitivity, contributing to irritable bowel syndrome. (i) Adipose tissue secretes various inflammatory mediators, causing intestinal hyperpermeability and nerve endings activation. (ii) Obesity and gastrointestinal microbiota could affect each other, and microbial metabolites can increase sensitivity of the colon. (iii) Vitamin D deficiency contributes to both fat accumulation and disruption of the intestinal mucosal barrier. (iv) Brain-gut axis may be another bridge from obesity to visceral hypersensitivity.

Gastric herpes simplex virus type 1 infection is associated with functional gastrointestinal disorders in the presence and absence of comorbid fibromyalgia: a pilot case-control study

PURPOSE

Animal studies have linked gastric herpesvirus infections to symptoms associated with functional gastrointestinal disorders (FGIDs). Herpesviruses have also been hypothesized to contribute to fibromyalgia (FM), a chronic pain syndrome frequently comorbid with FGIDs. The purpose of this study was to compare the prevalence of gastric herpesvirus infection in patients with FGIDs, with and without comorbid FM, to that of controls.

METHODS

For this pilot case-control study, we enrolled 30 patients who met both the Rome IV diagnostic criteria for one or more FGIDs and the American College of Rheumatology 2010 criteria for FM, 15 patients with one or more FGIDs without comorbid FM, and 15 control patients. Following endoscopic examination, gastric biopsies were analyzed for herpesvirus DNA and protein, Helicobacter pylori infection, and histological evidence of gastritis. Importantly, the viral nonstructural protein ICP8 was used as a marker to differentiate cell-associated actively replicating virus from latent infection and/or free virus passing through the GI tract.

RESULTS

Gastric herpes simplex virus type 1 (HSV-1) infection, as indicated by ICP8 presence, was significantly associated with FGIDs in the presence (OR 70.00, 95% CI 7.42-660.50; P < .001) and absence (OR 38.50, 95% CI 3.75-395.40; P < .001) of comorbid FM. Neither histological gastritis nor H. pylori infection were found to be associated with FGIDs or FM.

CONCLUSIONS

HSV-1 infection was identified in gastric mucosal biopsies from patients with diverse FGIDs, with and without comorbid FM. Larger, multi-center studies investigating the prevalence of this association are warranted.

Microbiome and diversity indices during blood stem cells transplantation - new perspectives?

OBJECTIVE

The human body is colonized by bacteria, fungi and viruses. Resident commensal bacteria are a fundamental line of resistance to colonization by exogenous microbes. They actively regulate the production of nutrients by the host through a negative feedback mechanism, in order to prevent the availability of nutrients for potential pathogens. While only a small fraction of these microorganism may be pathogenic, the relationship between host and commensal microbiome is now studied as a whole, impacting several aspects of the host biology. Some studies have made clear the progresses in examining the role of microbiome on transplants and graft versus host disease (GVHD) severity and its pathogenesis: the risk of complications from allogenic hematopoietic stem cells transplantation (HSCT) is greater with the highest mortality if a patient has a lower bacterial diversity in the gut prior to the transplantation process beginning. Microbiota-associated molecular patterns are directly recognized by pathogen recognition receptors. The development of molecular methods has greatly expanded our knowledge of the composition and function of the microbiome in health and disease, shortening the response times vs. microbiological culture tests. The gut flora can make the difference when it comes to allo-HSCT. The aim of the study was to monitor microbiome of 10 children during allo-HSCT.

METHODS

Oral specimens and gut faecal microbiome (100 grams) samples were collected at 2, 16, 24 days. The samples were analysed by polymerase chain reaction and primary sequencing was done. To calculate the biodiversity of microbiome the Shannon index and the Observed species index were chosen.

RESULTS

Our study suggests some differences in the diversity indices (DIs) in 5 children affected by GVHD vs. not affected. The DIs in oral and faecal specimens show in all patients a diminution in the post-transplant phase with an improvement in species diversity after 16 days from the transplant. The Observed species index in faeces specimens after 16 days was higher in patients which had not GVHD; moreover, patients with GVHD showed a deterioration at 24 days. Oral specimens after 24 days showed a parallel trend in the two groups. The Shannon index shows a downward trend in faeces specimens of the children with GVHD at 24 days; the children without GVHD recover a good trend of entropy. Oral specimens at 24 days show low entropy in the two groups. Very aggressive bacterial species as Cronobacter and Routella in the faeces specimens of a child had not serious consequences for disease status: Cronobacter were not present 24 days after transplantation.

CONCLUSIONS

The data show the microbial metabolome could have an impact on patients with GVHD vs. no GVHD. A better understanding of the role of the oral and gut microbiome in GVHD can give directions to move towards the development of innovative approaches for preventing GVHD following allo-HCT, reducing also antibiotic therapy.

General and abdominal obesity in relation to the prevalence of irritable bowel syndrome

BACKGROUND

Earlier studies on the obesity-IBS association have mostly been reported from Western nations, and limited data are available in this regard from developing countries. This study was performed to examine the association of general and abdominal obesity with Irritable bowel syndrome (IBS) in a Middle Eastern population.

METHODS

In this cross-sectional study, 4763 Iranian adults participated. Data on self-reported anthropometric measurements were collected, and BMI was calculated. Overweight and obesity were defined as 25 ≤ BMI < 30 and BMI ≥ 30 kg/m² , respectively. Also, we used WC measurements to define the three categories of normal (<94 cm in men <80 cm in women), abdominal overweight (94 ≤ WC < 102 in men and 80 ≤ WC < 88 in women), and abdominal obesity (WC ≥ 102 cm in men and WC ≥ 88 cm in women). Assessment of different GI symptoms including those related to IBS was done using a validated Persian version of the Rome III questionnaire. IBS was defined as the presence of recurrent abdominal pain or discomfort at least sometimes in the last 3 months associated with 2 or more of the following features: improvement with defecation, pain onset associated with a change in frequency of stool, and pain onset associated with a change in form (appearance) of stool.

KEY RESULTS

Irritable bowel syndrome was more prevalent among individuals with abdominal obesity compared with normal subjects (23.8% vs 19%). Neither in crude nor in adjusted models, we found any significant association between overweight and obesity and IBS [for overweight: OR: 0.95, 95% CI: 0.66-1.36 and for obesity: OR: 1.06, 95% CI: 0.85-1.31]. We observed a significant positive association between abdominally overweight and IBS in crude model (OR: 1.31, 95% CI: 1.09-1.60); however, this association became non-significant after adjustment for potential confounders (OR: 1.09, 95% CI: 0.82-1.44). Across BMI categories, neither in crude nor in adjusted models, we did not find any significant association between overweight (OR: 0.89, 95% CI: 0.62-1.27), obesity (OR: 1.05, 95% CI: 0.58-1.87), and abdominal pain severity. Abdominal overweight (OR: 0.96, 95% CI: 0.65-1.40) and obesity (OR: 1.61, 95% CI: 0.67-1.63) were not associated with abdominal pain severity.

CONCLUSIONS AND INFERENCES

It is concluded that general or abdominal obesity was not associated with odds of IBS. Future longitudinal studies are needed to clarify the association between obesity and IBS.

The Food-Specific Serum IgG Reactivity in Major Depressive Disorder Patients, Irritable Bowel Syndrome Patients and Healthy Controls

There is an increasing amount of evidence which links the pathogenesis of irritable bowel syndrome (IBS) with food IgG hyperreactivity. Some authors have suggested that food IgG hyperreactivity could be also involved in the pathophysiology of major depressive disorder (MDD). The aim of this study was to compare levels of serum IgG against 39 selected food antigens between three groups of participants: patients with MDD (MDD group), patients with IBS (IBS group) and healthy controls (HC group). The study included 65 participants (22 in the MDD group, 22 in the IBS group and 21 in the HC group). Serum IgG levels were examined using enzyme-linked immunosorbent assay (ELISA). Medical records, clinical data and laboratory results were collected for the analysis. IgG food hyperreactivity (interpreted as an average of levels of IgG antibodies above 7.5 µg/mL) was detected in 28 (43%) participants, including 14 (64%) from the MDD group, ten (46%) from the IBS group and four (19%) from the HC group. We found differences between extreme IgG levels in MDD versus HC groups and in IBS versus HC groups. Patients with MDD had significantly higher serum levels of total IgG antibodies and IgG against celery, garlic and gluten compared with healthy controls. The MDD group also had higher serum IgG levels against gluten compared with the IBS group. Our results suggest dissimilarity in immune responses against food proteins between the examined groups, with the highest immunoreactivity in the MDD group. Further studies are needed to repeat and confirm these results in bigger cohorts and also examine clinical utility of IgG-based elimination diet in patients with MDD and IBS.

Progress with treating the microbial dysbiosis associated with irritable bowel syndrome

PURPOSE OF REVIEW

Microbial dysbiosis is receiving increasing attention as possibly being important in the pathophysiology of irritable bowel syndrome. This review will summarize the most recent literature addressing attempts to explore and target the microbiome in patients with irritable bowel syndrome.

RECENT FINDINGS

Manipulation of the intestinal microbiota in irritable bowel syndrome is receiving increasing attention. Traditionally, dietary manipulation has been utilized. There is now evidence that a low fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet has not only been able to improve symptoms, but may have an effect on the gut microbiota. Probiotics are a safe and attractive option for the manipulation of the microbiota. There have been a number of well-designed trials examining the efficacy of certain strains of bacteria, and even yeasts are receiving attention. The role of antibiotics remains controversial and it seems likely that their use should currently be limited to those individuals with small intestinal bacterial overgrowth. Interest in the role of faecal microbiota transplantation for the treatment of a number of gastrointestinal conditions has intensified and irritable bowel syndrome is no exception.

SUMMARY

The manipulation of the microbial dysbiosis is gaining momentum. Further research, however, is required in order to identify the most appropriate treatment option for each individual patient.

Gastric Enterovirus Infection: A Possible Causative Etiology of Gastroparesis

BACKGROUND

Gastroparesis (GP) is a disabling chronic gastroenterologic disorder with high morbidity that severely impacts patients' quality of life. GP can present acutely after a viral-like gastrointestinal illness resulting in speculation that in some patients, neurologic damage caused by the infection might underlie the pathogenesis of idiopathic gastroparesis (IGP).

AIMS

The aim of this study is to document case reports of Enterovirus (EV) infection as a possible cause of IGP.

METHODS

Eleven patients referred with a diagnosis of GP underwent workup to exclude known causes of GP. Those with a history of flu-like symptoms or gastroenteritis prior to onset of GP symptoms had gastric biopsies taken during upper endoscopy to assess for the presence of gastric mucosal EV infection. Data on presenting symptoms, extra-intestinal symptoms and conditions, prior nutritional support requirements, upper endoscopy findings, and response to therapy were cataloged.

RESULTS

Eleven patients were diagnosed as IGP. Nine had active EV infection on gastric biopsies and were included (7/9 female, mean age 43 years). Eight out of nine received EV treatment with antivirals and/or immune therapies, with a wide degree of variability in treatment regimens. Four out of eight who received EV treatment had symptomatic improvement. One patient had stable symptoms. Three patients are currently undergoing therapy.

CONCLUSIONS

Gastric EV infection was frequently detected (82 %) in patients undergoing investigation for IGP. Antiviral and/or immune therapies against EV seem to be favorable, as most of our patients had resolution of their GP symptoms after treatment. This is the first study to identify EV as a possible infectious etiology of IGP.

Palmitoylethanolamide normalizes intestinal motility in a model of post-inflammatory accelerated transit: involvement of CB₁ receptors and TRPV1 channels

BACKGROUND AND PURPOSE

Palmitoylethanolamide (PEA), a naturally occurring acylethanolamide chemically related to the endocannabinoid anandamide, interacts with targets that have been identified in peripheral nerves controlling gastrointestinal motility, such as cannabinoid CB1 and CB2 receptors, TRPV1 channels and PPARα. Here, we investigated the effect of PEA in a mouse model of functional accelerated transit which persists after the resolution of colonic inflammation (post-inflammatory irritable bowel syndrome).

EXPERIMENTAL APPROACH

Intestinal inflammation was induced by intracolonic administration of oil of mustard (OM). Mice were tested for motility and biochemical and molecular biology changes 4 weeks later. PEA, oleoylethanolamide and endocannabinoid levels were measured by liquid chromatography-mass spectrometry and receptor and enzyme mRNA expression by qRT-PCR.

KEY RESULTS

OM induced transient colitis and a functional post-inflammatory increase in upper gastrointestinal transit, associated with increased intestinal anandamide (but not 2-arachidonoylglycerol, PEA or oleoylethanolamide) levels and down-regulation of mRNA for TRPV1 channels. Exogenous PEA inhibited the OM-induced increase in transit and tended to increase anandamide levels. Palmitic acid had a weaker effect on transit. Inhibition of transit by PEA was blocked by rimonabant (CB1 receptor antagonist), further increased by 5'-iodoresiniferatoxin (TRPV1 antagonist) and not significantly modified by the PPARα antagonist GW6471.

CONCLUSIONS AND IMPLICATIONS

Intestinal endocannabinoids and TRPV1 channel were dysregulated in a functional model of accelerated transit exhibiting aspects of post-inflammatory irritable bowel syndrome. PEA counteracted the accelerated transit, the effect being mediated by CB1 receptors (possibly via increased anandamide levels) and modulated by TRPV1 channels.

Lactobacillus reuteri in children with functional abdominal pain (FAP)

AIM

Functional abdominal pain (FAP) is a frequent condition affecting 10-20% of children and can be considered within the classification of functional gastrointestinal disorders (FGID). The objective of this study was to determine the effect of daily supplementation with the probiotic Lactobacillus reuteri DSM 17938 in children with FAP.

METHODS

The children (aged 6-16 years) were screened for FAP as defined in the Rome III criteria and 60 patients were recruited in this double-blind, randomised, placebo-controlled trial. The children were randomly allocated to receive either L. reuteri (2×10(8)  CFU/day) or identical placebo for 4 weeks followed by a 4-week follow-up period without supplementation. Frequency and intensity of pain was self-recorded by the subjects.

RESULTS

The L. reuteri-supplemented children had significantly lower pain intensity compared with the placebo controls.

CONCLUSIONS

Supplementation with L. reuteri reduced perceived abdominal pain intensity, which may encourage clinicians to use this probiotic in children with FAP.

A double-blind placebo-controlled trial to study therapeutic effects of probiotic Escherichia coli Nissle 1917 in subgroups of patients with irritable bowel syndrome

PURPOSE

To study the therapeutic effects of probiotic Escherichia coli Nissle 1917 (EcN) in irritable bowel syndrome (IBS) and identify subgroups benefiting most.

BACKGROUND

Some trials investigating therapeutic effects in irritable bowel syndrome have shown benefits in IBS subgroups only. Probiotic treatment seems to be promising.

METHODS

Patients with irritable bowel syndrome (120; Rome II) were recruited to a prospective double-blind study and randomized to either EcN (n = 60) or placebo (n = 60) given for 12 weeks. Objectives were to describe efficacy and safety of EcN in different groups of irritable bowel syndrome. Outcome was assessed by 'Integrative Medicine Patient Satisfaction Scale'.

RESULTS

Altogether, the responder rate was higher in the EcN than in the placebo group. However, only after 10 and 11 weeks, the differences were significant (Δ 20.0% points [95% CI 2.6; 37.4], p = 0.01 and Δ 18.3% points [95% CI 1.0; 35.7], p = 0.02, respectively). The best response was observed in the subgroup of patients with gastroenteritis or antibiotics prior to irritable bowel syndrome onset (Δ 45.7% points, p = 0.029). No significant differences were observed in any other subgroup. Both treatment groups showed similar adverse events and tolerance.

CONCLUSIONS

Probiotic EcN shows effects in irritable bowel syndrome, especially in patients with altered enteric microflora, e.g. after gastroenterocolitis or administration of antibiotics.

Do probiotics improve symptoms in patients with irritable bowel syndrome?

There is increasing evidence that inflammation or a disturbance of the flora within the gut might contribute to the pathogenesis of irritable bowel syndrome (IBS), at least in a proportion of cases. As a consequence it has been speculated that, as some probiotic bacteria have a range of anti-inflammatory and immunomodulatory properties, the administration of such organisms might prove to be beneficial in this condition. It has to be acknowledged that the quality and design of trials of probiotics in IBS has been somewhat variable but the majority have shown benefit, although some bacteria appear to be more effective than others. More recent studies using Bifidobacterium infantis 35624 and Bifidobacterium lactis DN-173-010 have given particularly encouraging results. Issues for the future include determining which organisms are most effective, defining optimal doses, comparing methods of delivery and assessing the role of mixtures or the addition of prebiotics.

Post-infectious irritable bowel syndrome: the past, the present and the future

BACKGROUND

Irritable bowel syndrome (IBS), once thought to be a psychosomatic disease, is being considered to be more organic. Post-infectious IBS (PI-IBS), defined as acute onset IBS (by Rome criteria) after gastrointestinal infection in an individual without prior IBS with two or more of the followings: fever, vomiting, diarrhea, a positive stool culture. The recent and old literature of PI-IBS will be reviewed. Future directions for research will be presented.

METHODS

Literature on PI-IBS was reviewed by electronic search and cross references of these papers.

RESULTS

Interest in studies on PI-IBS, which was described five to six decades ago, re-surfaced recently. 3.6 to 32% patients with acute gastroenteritis develop PI-IBS during 3-12 month follow-up. PI-IBS is commonly diarrhea predominant. Factors implicated in development include nature of pathogens, duration and severity of diarrhea, younger age, female gender and psychological co-morbidities like anxiety and depression. The pathogenesis of PI-IBS is largely related to continuing gut inflammation due to inability of the host to contain the inflammatory reaction, altered gut microbiota, increased intestinal permeability, muscle hyper-contractility and visceral hypersensitivity. There could be an overlap between PI-IBS and post-infectious malabsorption syndrome (PI-MAS), popularly known as tropical sprue.

CONCLUSIONS

Development of IBS in a subset of patients with acute gastroenteritis is uncontested. This is expected to open a paradigm shift in understanding the pathogenesis of IBS. Future studies should address the issue of overlap of PI-IBS and PI-MAS. Exploring the molecular mechanisms of pathogenesis of PI-IBS may help to design preventive and therapeutic strategies.

Existing and emerging therapies for irritable bowel syndrome

INTRODUCTION

Irritable bowel syndrome is a common disorder that is associated with a significant impact on both affected individuals and society. While the pathophysiology of irritable bowel syndrome remains unknown, knowledge regarding the normal and abnormal functions of the gut and its complex interaction with the body's nervous systems continues to shed light on the multifactorial origins of irritable bowel syndrome symptoms. This article provides an overview of the current knowledge of the therapeutic approaches to irritable bowel syndrome.

AREAS COVERED

A search of the online bibliographic databases MEDLINE and EMBASE was performed in order to identify all relevant articles published between 1980 and 2010. The search was enhanced with the use of a medical librarian. Bibliographies from potentially relevant articles were manually searched.

EXPERT OPINION

The therapeutic options for irritable bowel syndrome are rapidly evolving beyond traditional symptom-based therapies, such as fiber, antispasmodics, antidiarrheals and laxatives, and are moving toward agents with organ-specific receptor selectivity directed, in many cases, at specific gastrointestinal functions.

Clostridium perfringens epsilon toxin inhibits the gastrointestinal transit in mice

Epsilon toxin produced by Clostridium perfringens type B and D is a potent toxin that is responsible for a highly fatal enterotoxemia in sheep and goats. In vitro, epsilon toxin produces contraction of the rat ileum as the result of an indirect action, presumably mediated through the autonomic nervous system. To examine the impact of epsilon toxin in the intestinal transit, gastric emptying (GE) and gastrointestinal transit (GIT) were evaluated after intravenous and oral administration of epsilon toxin in mice. Orally administered epsilon toxin produced a delay on the GIT. Inhibition of the small intestinal transit was observed as early as 1 h after the toxin was administered orally but the effects were not observed after 1 week. Epsilon toxin also produced an inhibition in GE and a delay on the GIT when relatively high toxin concentrations were given intravenously. These results indicate that epsilon toxin administered orally or intravenously to mice transitorily inhibits the GIT. The delay in the GIT induced by epsilon toxin could be relevant in the pathogenesis of C. perfringens type B and D enterotoxemia.

LX-1031, a tryptophan 5-hydroxylase inhibitor, and its potential in chronic diarrhea associated with increased serotonin

LX-1031 is an oral, small molecule tryptophan 5-hydroxylase (TPH) inhibitor that reduces serotonin (5-HT) synthesis peripherally. It has potential for illnesses characterized by excess 5-HT, such as diarrhea-predominant irritable bowel syndrome (IBS-D) and carcinoid diarrhea. In vitro, inhibition of TPH1 occurred in 10(-8) -10(-7) mol L(-1) range. In vivo in rodents, LX-1031 has no effect on brain 5-HT while dose-dependently reducing 5-HT, particularly in the small bowel. After oral LX1031 in humans, systemic exposure is very low, plasma concentrations are linear in dose range 250-750 mg q.i.d.; the median T(1/2) for elimination is ∼ 20 h, and repeat administration for 14 days doubles C(max) . In ascending-single-dose and multiple-dose (14 days) trials in healthy volunteers, LX-1031, 2-4 g day(-1) significantly reduced urinary 5-hydroxyindoleacetic acid (5-HIAA) starting by Day 5, and persisting over the 14 day exposure. There are no dose-limiting toxicities in healthy subjects or remarkable adverse effects in clinical trials to date. Over a 28-day treatment period, LX-1031 was associated with improved weekly global scores (2/4 weeks) and improved stool consistency with lower urinary 5-HIAA excretion. LX-1031 appears promising for chronic diarrhea associated with increased 5-HT expression including IBS-D. Optimal doses, efficacy and safety in IBS clinical trials need to be fully elucidated; low systemic exposure, selectivity for TPH1 over TPH2, and lack of effect on brain 5-HT in several species suggest that LX-1031 is unlikely to cause affective disorders.

Current medical treatments of dyspepsia and irritable bowel syndrome

Dyspepsia is a highly prevalent condition characterized by symptoms originating in the gastroduodenal region without underlying organic disorder. Treatment modalities include acid-suppressive drugs, gastroprokinetic drugs, Helicobacter pylori eradication therapy, tricyclic antidepressants, and psychological therapies. Irritable bowel syndrome is a multifactorial, lower functional gastrointestinal disorder involving disturbances of the brain-gut axis. The pathophysiology provides the basis for pharmacotherapy: abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, intraluminal changes, and mucosal immune activation. Medications targeting chronic constipation or diarrhea may also relieve irritable bowel syndrome. Novel approaches to treatment require approval, and promising agents are guanylate cyclase cagonists, atypical benzodiazepines, antibiotics, immune modulators, and probiotics.

Pathogenic mechanisms of postinfectious functional gastrointestinal disorders: results 3 years after gastroenteritis

OBJECTIVE

Functional gastrointestinal disorders (FGID) may appear after acute gastroenteritis. The aim of this study was to evaluate the possible mechanisms (inflammation, visceral hypersensitivity, psychological and immunogenetic factors) related to the development of postinfectious (PI) FGID 3 years after a Salmonella outbreak.

MATERIAL AND METHODS

Biopsies of the antrum, and right- and left colon from 16 PI-FGID patients, 8 PI control patients, and 18 healthy controls (H-controls) were processed for immunohistochemistry, cytokines, and mast-cell electron microscopy. DNA was typed for cytokine gene polymorphisms. Visceral sensitivity (satiety test and rectal barostat) and psychological factors (SCL-90 and vital events) were assessed.

RESULTS

The number of mast cells and T lymphocytes was similar among the groups in all locations. Mast cells within 5 microm of nerve fibers of both PI groups were increased compared to H-controls: (stomach: 5.6+/-1.2 versus 6.6+/-1.5 versus 2.5+/-1.1; right colon: 9.7+/-1.3 versus 8.0+/-1.3 versus 4.1+/-1.7; left colon: 8.9+/-0.9 versus 8.5+/-1.8 versus 2.2+/-2.0 per field) (p<0.05). No differences in the production of IL-1beta, IL-1ra, IL-6, and IL-10 or in their genotypes were found. PI-FGID patients showed a lower pain threshold to rectal distention (29+/-2 versus 37+/- 2 mmHg; p<0.05). Scores for anxiety (0.63+/-0.11 versus 0.28+/-0.14) and somatization (1.01+/-0.15 versus 0.45+/-0.15) were higher in PI-FGID patients than in PI controls (p<0.05). The number of stressful life events was not significantly different between both PI groups.

CONCLUSIONS

Three years after salmonellosis, PI-FGID patients showed no evidence of inflammation in the gastric or colonic mucosa, but visceral sensitivity and anxiety/somatization levels were increased. The close anatomical mast cell-nerve fibers relation does not seem to be related to the FGID but to the infection itself.

Current and novel therapeutic options for irritable bowel syndrome management

Irritable bowel syndrome is a functional gastrointestinal disorder affecting up to 3-15% of the general population in western countries. It is characterised by unexplained abdominal pain, discomfort, and bloating in association with altered bowel habits. The pathophysiology of irritable bowel syndrome is multifactorial involving disturbances of the brain-gut axis. The pathophysiology provides the rationale for pharmacotherapy: abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, autonomic dysfunction, and mucosal immune activation. Understanding the mechanisms, and their mediators or modulators including neurotransmitters and receptors have led to several therapeutic approaches including agents acting on the serotonin receptor or serotonin transporter system, antidepressants, novel selective anticholinergics, alpha-adrenergic agonists, opioid agents, cholecystokinin-antagonists, neurokinin-antagonists, somatostatin receptor agonists, corticotropin releasing factor antagonists, chloride channel activators, guanylate cyclase-c agonists, melatonin, atypical benzodiazepines, antibiotics, immune modulators and probiotics. The mechanisms and current evidence regarding efficacy of these agents are reviewed.

Slow synaptic transmission in myenteric AH neurons from the inflamed guinea pig ileum

We investigated the effect of inflammation on slow synaptic transmission in myenteric neurons in the guinea pig ileum. Inflammation was induced by the intraluminal injection of trinitrobenzene sulfonate, and tissues were taken for in vitro investigation 6-7 days later. Brief tetanic stimulation of synaptic inputs (20 Hz, 1 s) induced slow excitatory postsynaptic potentials (EPSPs) in 49% and maintained postsynaptic excitation that lasted from 27 min to 3 h in 13% of neurons from the inflamed ileum. These neurons were classified electrophysiologically as AH neurons; 10 were morphological type II neurons, and one was type I. Such long-term hyperexcitability after a brief stimulus is not encountered in enteric neurons of normal intestine. Electrophysiological properties of neurons with maintained postsynaptic excitation were similar to those of neurons with slow EPSPs. Another form of prolonged excitation, sustained slow postsynaptic excitation (SSPE), induced by 1-Hz, 4-min stimulation, in type II neurons from the inflamed ileum reached its peak earlier but had lower amplitude than that in control. Unlike slow EPSPs and similar to SSPEs, maintained excitation was not inhibited by neurokinin-1 or neurokinin-3 receptor antagonists. Maintained postsynaptic excitation was not influenced by PKC inhibitors, but the PKA inhibitor, H-89, caused further increase in neuronal excitability. In conclusion, maintained excitation, observed only in neurons from the inflamed ileum, may contribute to the dysmotility, pain, and discomfort associated with intestinal inflammation.

Electrophysiologic, morphologic, and serologic features of chronic unexplained nausea and vomiting: lessons learned from 121 consecutive patients

BACKGROUND

Despite substantive morbidity, unexplained nausea and vomiting has not been evaluated in a systematic manner via surgically obtained biopsies and direct electrophysiology of the gut, and this information has not been correlated with serologic information. We investigated consecutive patients with unexplained and refractory chronic nausea and vomiting to define the presence of morphologic, physiologic, and/or serologic abnormalities.

METHODS

In all, 101 of 121 consecutive patients who experienced chronic nausea and vomiting of unknown etiology evaluated in 1 tertiary referral center over a 10-year period were profiled qualitatively by full-thickness small bowel biopsies with hematoxylin and eosin (H&E) and Smith's Silver stains, quantitatively by intraoperative gastric electrophysiology, and semiquantitatively, when it became available, by serum autoimmune Western blot analysis.

RESULTS

Overall, 79 of 101 patients had abnormal full-thickness biopsy (70 neuropathies and 9 myopathies) and frequent serum autoimmune abnormalities (mean score = 13.2, normal < 3.0). In addition, 96 of 101 patients had abnormal frequency and/or uncoupling on gastric electrophysiology. Patients with small-intestinal myopathy showed a diversity of diagnoses; some patients with neuropathy had abdominal pain that correlated with autoimmune scores on Western blot.

CONCLUSION

Patients with refractory and unexplained nausea and vomiting have a high incidence of both small bowel morphologic abnormalities (primarily neuropathies) and gastric electrophysiologic abnormalities, which are associated commonly with serologic autoimmune activation. Similar histomorphologic, physiologic, and serologic measures should be considered in the diagnostic evaluation of any patient with refractory or unexplained nausea and vomiting.

Hypnotherapy for irritable bowel syndrome: the response of colonic and noncolonic symptoms

There is now good evidence that hypnotherapy benefits a substantial proportion of patients with irritable bowel syndrome and that improvement is maintained for many years. Most patients seen in secondary care with this condition also suffer from a wide range of noncolonic symptoms such as backache and lethargy, as well as a number of musculoskeletal, urological, and gynaecological problems. These features do not typically respond well to conventional medical treatment approaches, but fortunately, their intensity is often reduced by hypnosis. The mechanisms by which hypnosis mediates its benefit are not entirely clear, but there is evidence that, in addition to its psychological effects, it can modulate gastrointestinal physiology, alter the central processing of noxious stimuli, and even influence immune function.

Alterations in mucosal immunity identified in the colon of patients with irritable bowel syndrome

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) has been associated with mucosal dysfunction, mild inflammation, and altered colonic bacteria. We used microarray expression profiling of sigmoid colon mucosa to assess whether there are stably expressed sets of genes that suggest there are objective molecular biomarkers associated with IBS.

METHODS

Gene expression profiling was performed using Human Genome U133 Plus 2.0 (Affymetrix) GeneChips with RNA from sigmoid colon mucosal biopsy specimens from 36 IBS patients and 25 healthy control subjects. Real-time quantitative polymerase chain reaction was used to confirm the data in 12 genes of interest. Statistical methods for microarray data were applied to search for differentially expressed genes, and to assess the stability of molecular signatures in IBS patients.

RESULTS

Mucosal gene expression profiles were consistent across different sites within the sigmoid colon and were stable on repeat biopsy over approximately 3 months. Differentially expressed genes suggest functional alterations of several components of the host mucosal immune response to microbial pathogens. The most strikingly increased expression involved a yet uncharacterized gene, DKFZP564O0823. Identified specific genes suggest the hypothesis that molecular signatures may enable distinction of a subset of IBS patients from healthy controls. By using 75% of the biopsy specimens as a validation set to develop a gene profile, the test set (25%) was predicted correctly with approximately 70% accuracy.

CONCLUSIONS

Mucosal gene expression analysis shows there are relatively stable alterations in colonic mucosal immunity in IBS. These molecular alterations provide the basis to test the hypothesis that objective biomarkers may be identified in IBS and enhance understanding of the disease.

Probiotic agents in the treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is characterized by abdominal pain and alterations in bowel habits. Several pathogenetic factors, such as altered intestinal motility, visceral hypersensitivity, serotonin system abnormalities and psychic disturbances have been identified. Recently, a pathogenetic role of intestinal microflora has been shown in IBS: viral or bacterial infection can trigger post-infectious IBS; some patients have small intestinal bacterial overgrowth; the composition of patients' enteric flora is altered; and minimal inflammatory changes, consistent with the pro-inflammatory role of bacteria, have been demonstrated. Probiotics may, therefore, offer a rational therapeutic approach to IBS. The data available on the use of probiotics in IBS are still limited and results of controlled clinical trials are contradictory because they have been performed using different species, dosages, treatment durations and end-points for results evaluation. A critical evaluation of the therapeutic role of the various probiotics in IBS is presented in this article.

Disturbed in vitro adrenergic modulation of cytokine production in inflammatory bowel diseases in remission

OBJECTIVE

Psychological stress has been implicated in the pathophysiology of both inflammatory and functional gastrointestinal (GI) diseases. The goal of this study was to address neuroendocrine modulation of cytokine production by peripheral blood cells in GI diseases.

METHODS

We analyzed the in vitro effects of the beta-adrenergic agonist terbutaline and the glucocorticoid agonist dexamethasone on TNF-alpha and IL-10 production by LPS-stimulated monocytes in whole cell blood cultures in patients with inflammatory bowel diseases in remission (N=10), diarrhoea-predominant irritable bowel syndrome (IBS, N=12), patients with a recent gastroenteritis (post-infectious group, N=10), and healthy controls (N=15).

RESULTS

In response to terbutaline, there was a significant increase in IL-10 production (concentration effect: p<0.05), which was diminished in IBD (group effect: p<0.01), comparable in IBS and controls, but enhanced in the post-infectious group (group x concentration effect: p<0.05). In contrast, terbutaline resulted in a concentration-dependent suppression of TNF-alpha production, which was comparable in all groups. Dexamethasone suppressed TNF-alpha production in a dose-dependent manner in all groups, but this effect was significantly more pronounced in post-infectious subjects (group effect: p<0.05).

CONCLUSIONS

In IBD, disturbed adrenergic regulation of IL-10 could be part of the mechanism(s) underlying the modulation of disease activity by psychological stress. Diarrhoea-predominant IBS was not associated with altered adrenergic or glucocorticoid regulation of cytokine production by peripheral blood cells, whereas a recent history of gastroenteritis was associated with disturbed neuroendocrine modulation of cytokine production, which may play role in the pathophysiology of post-infectious IBS.

Irritable bowel syndrome: recent and novel therapeutic approaches

Irritable bowel syndrome (IBS) is a highly prevalent functional gastrointestinal disorder affecting up to 3-15% of the general population in Western countries. It is characterised by unexplained abdominal pain, discomfort and bloating in association with altered bowel habits. The pathophysiology of IBS is considered to be multifactorial, involving disturbances of the brain-gut-axis: IBS has been associated with abnormal gastrointestinal motor functions, visceral hypersensitivity, psychosocial factors, autonomic dysfunction and mucosal inflammation. Traditional IBS therapy is mainly symptom oriented and often unsatisfactory. Hence, there is a need for new treatment strategies. Increasing knowledge of brain-gut physiology, mechanisms, and neurotransmitters and receptors involved in gastrointestinal motor and sensory function have led to the development of several new therapeutic approaches. This article provides a systematic overview of recently approved or novel medications that show promise for the treatment of IBS; classification is based on the physiological systems targeted by the medication. The article includes agents acting on the serotonin receptor or serotonin transporter system, novel selective anticholinergics, alpha-adrenergic agonists, opioid agents, cholecystokinin antagonists, neurokinin antagonists, somatostatin receptor agonists, neurotrophin-3, corticotropin releasing factor antagonists, chloride channel activators, guanylate cyclase-c agonists, melatonin and atypical benzodiazepines. Finally, the role of probiotics and antibacterials in the treatment of IBS is summarised.

Irritable bowel syndrome: update on colonic neuromuscular dysfunction and treatment

Recent discoveries regarding the relatively autonomous workings of the enteric nervous system have expanded our understanding of the pathophysiology of irritable bowel syndrome (IBS). However, the heterogeneity of the pathogenesis of IBS continues to create unique challenges for clinicians who care for these patients. Advances in our understanding of the structure and functions of the brain-gut axis and its interplay with other potentially important factors, such as genetic predisposition, inflammation, and psychological unrest, have led to new developments in the field of targeted pharmacotherapy for IBS sufferers. Therapies designed specifically to modulate gut motility, secretion, and/or sensation have been created and introduced into the marketplace in recent years, and additional designer formulations are in various stages of development. Concurrently, new discoveries of potentially beneficial effects of agents approved for other, often non-gastroenterologic, conditions continue to be reported. This article reviews the accumulating body of evidence supporting the importance of neuromuscular dysfunction as a central cause of IBS symptoms and provides a rationale for the discussion of current and future drug development.

Probiotics and irritable bowel syndrome: rationale, putative mechanisms, and evidence of clinical efficacy

The irritable bowel syndrome (IBS) follows an acute, presumably infectious diarrheal illness in approximately 15% of patients. There may be a persistent, mild inflammatory state with changes in mucosal function or structure. Changes in the colonic bacterial flora reported in IBS seem related to predominant bowel. Colonic bacteria normally metabolize nutrients with the formation of gas and short chain fatty acids. The latter may induce propulsive contractions and accelerate colonic transit or they may enhance fluid and sodium absorption in the colon. This review addresses the mechanisms, rationale and current evidence for the efficacy of probiotics, including Lactobacilli, Bifidobacteria, and VSL#3, in the treatment of IBS. The mechanisms influenced by probiotics include immune function, motility, and the intraluminal milieu. Probiotics may suppress the low-grade inflammation associated with IBS or restore normal local immune function. Lactobacilli and Bifidobacteria subspecies are able to deconjugate and absorb bile acids, potentially reducing the colonic mucosal secretion of mucin and fluids that may contribute to functional diarrhea or IBS with diarrhea. Therapeutic trials show the potential benefit of Bifidobacteria or Lactobacilli species alone or in the specific probiotic combination, VSL#3, on symptoms in IBS. Colonic transit was retarded in IBS patients treated with VSL#3 without induction of significant changes in bowel function. In summary, probiotics are promising therapies in IBS.

Postinfectious gastroparesis related to autonomic failure: a case report

BACKGROUND AND AIM

Severe dysautonomia may be secondary to viral infections, resulting in impaired autoimmune, cardiovascular, urinary and digestive dysfunction. Herein, we present a case of a 31-year-old white female patient who had severe gastroparesis related to autonomic failure following an episode of acute gastroenteritis. This seems to be the first report providing thorough assessment of the enteric and autonomic nervous system by analysis of full-thickness small intestinal biopsies, cardiovagal testing and autopsy.

HOSPITAL COURSE

This patient affected by a severe gastroparesis was treated with antiemetics, prokinetics, analgesics and gastric electrical stimulation to control symptoms. Nutritional support was made using jejunal feeding tube and, in the final stage of disease, with total parenteral nutrition. Autonomic studies revealed minimal heart rate variability and a disordered Valsalva manoeuvre although the enteric nervous system and the smooth muscle layer showed a normal appearance. Hospital courses were complicated by episodes of bacteraemia and fungemia. Serum antiphospholipid antibodies were noted but despite anticoagulation, she developed a pulmonary embolism and shortly thereafter the patient died. Autopsy revealed acute haemorrhagic Candida pneumonia with left main pulmonary artery thrombus. Sympathetic chain analysis revealed decreased myelinated axons with vacuolar degeneration and patchy inflammation consistent with Guillain-Barre syndrome. The evaluation of the enteric nervous system in the stomach and small bowel revealed no evidence of enteric neuropathy or myopathy.

CONCLUSION

A Guillain-Barre-like disease with gastroparesis following acute gastroenteritis is supported by physiological and autonomic studies with histological findings.

IgG-mediated food intolerance in irritable bowel syndrome: a real phenomenon or an epiphenomenom?

Abnormal reactions to food probably contribute to the complex pathophysiology of irritable bowel syndrome, but the mechanisms involved remain unclear. Following the recent identification of subtle mucosal inflammation in at least some patients with the disorder, perhaps now is the time to revisit some of the immunological reactions to dietary antigens that, in the past, have been dismissed as irrelevant.

Potential future therapies for irritable bowel syndrome: will disease modifying therapy as opposed to symptomatic control become a reality?

Irritable bowel syndrome can remit spontaneously, implying cure is possible. Predictors of good prognosis include a short history, acute onset(possibly postinfective origin), absence of psychological disorders, and resolution of chronic life stressors. Possible-disease modifying treatments with long-lasting effects include diet and anti-inflammatory and psychological treatments. Dietary modifications, which often involve excluding dairy and wheat products, are successful in some patients. Anti-inflammatory treatments have been subjected to one RCT in postinfective IBS without benefit. Probiotics may have benefit in altering bacterial flora and as anti-inflammatory agents, but further trials are needed before they can be recommended. Psychological treatments may produce long-lasting responses. Relaxation therapy appears to have a nonspecific benefit. Psychotherapy has been shown to have long-term benefit and is particularly acceptable to, and effective for, those with overt psychological distress. Hypnotherapy has been shown to be effective in randomized placebo controlled trials and has a sustained effect.

Acute colitis induction by oil of mustard results in later development of an IBS-like accelerated upper GI transit in mice

Oil of mustard (OM) is a potent neuronal activator that promotes allodynia and hyperalgesia within minutes of application. In this study, OM was used to induce an acute colitis. We also investigated whether intracolonic OM-induced inflammation alters gastrointestinal (GI) function over a longer time frame as a model of postinflammatory irritable bowel syndrome (PI-IBS). Mice given a single administration of 0.5% OM developed a severe colitis that peaked at day 3, was reduced at day 7, and was absent by day 14. At the peak response, there was body weight loss, colon shrinkage, thickening and weight increases, distension of the proximal colon, and diarrhea. Macroscopic inspection of the distal colon revealed a discontinuous pattern of inflammatory damage and occasional transmural ulceration. Histological examination showed loss of epithelium, an inflammatory infiltrate, destruction of mucosal architecture, edema, and loss of circular smooth muscle architecture. OM administration increased transit of a carmine dye bolus from 58% of the total length of the upper GI tract in untreated age-matched controls to as high as 74% when tested at day 28 post-OM. Mice in the latter group demonstrated a significantly more sensitive response to inhibition of upper GI transit by the mu-opioid receptor agonist loperamide compared with normal mice. OM induces a rapid, acute, and transient colitis and, in the longer term, functional changes in motility that are observed when there is no gross inflammation and thereby is a model of functional bowel disorders that mimic aspects of PI-IBS in humans.

Inflammation as a basis for functional GI disorders

The term 'Functional diseases' implies symptoms arising from an organ without overt pathology. However this is more apparent than real since inflammation often leaves changes in nerves and mucosal function only apparent with specialised techniques. Acute onset functional dyspepsia accounts for around 1/5 of functional dyspepsia and is characterised by early satiety, nausea, vomiting and weight loss. Impaired postcibal fundal accommodation may underlie some of these symptoms. Post infectious gastroparesis is much rarer and is associated with markedly delayed gastric emptying and antral hypomotility. Approximately 1/10 of IBS cases describe a post infectious onset. Post infectious IBS is typically of the diarrhoea-predominant type. Post inflammatory functional diseases tend to be associated with less psychological abnormalities and have a better prognosis than other functional diseases. There are isolated anecdotal reports of symptom response to anti-inflammatory treatments but larger controlled trials are needed.

Inflammation as a basis for functional GI disorders

The term 'Functional diseases' implies symptoms arising from an organ without overt pathology. However this is more apparent than real since inflammation often leaves changes in nerves and mucosal function only apparent with specialised techniques. Acute onset functional dyspepsia accounts for around 1/5 of functional dyspepsia and is characterised by early satiety, nausea, vomiting and weight loss. Impaired postcibal fundal accommodation may underlie some of these symptoms. Post infectious gastroparesis is much rarer and is associated with markedly delayed gastric emptying and antral hypomotility. Approximately 1/10 of IBS cases describe a post infectious onset. Post infectious IBS is typically of the diarrhoea-predominant type. Post inflammatory functional diseases tend to be associated with less psychological abnormalities and have a better prognosis than other functional diseases. There are isolated anecdotal reports of symptom response to anti-inflammatory treatments but larger controlled trials are needed.