Updates on treatment of irritable bowel syndrome

The potential influence of melatonin on mitochondrial quality control: a review

Mitochondria are critical for cellular energetic metabolism, intracellular signaling orchestration and programmed death regulation. Therefore, mitochondrial dysfunction is associated with various pathogeneses. The maintenance of mitochondrial homeostasis and functional recovery after injury are coordinated by mitochondrial biogenesis, dynamics and autophagy, which are collectively referred to as mitochondrial quality control. There is increasing evidence that mitochondria are important targets for melatonin to exert protective effects under pathological conditions. Melatonin, an evolutionarily conserved tryptophan metabolite, can be synthesized, transported and metabolized in mitochondria. In this review, we summarize the important role of melatonin in the damaged mitochondria elimination and mitochondrial energy supply recovery by regulating mitochondrial quality control, which may provide new strategies for clinical treatment of mitochondria-related diseases.

Efficacy of Oral Psyllium in Pediatric Irritable Bowel Syndrome: A Double-Blind Randomized Control Trial

OBJECTIVE

Pediatric irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder with variable response to various therapeutic agents. Psyllium has been proven to be effective in adults; however, there is no study in children. The objective of this study is to evaluate the efficacy of psyllium husk as compared to placebo in pediatric IBS patients.

METHODS

In this double-blind randomized controlled trial, 43 children were assigned to psyllium arm (Group A) and 38 into placebo arm (Group B). Severity is assessed at baseline and after 4 weeks of treatment using IBS severity scoring scale (IBS-SSS) and classified into mild, moderate, and severe categories. Categorical data was compared with chi-square test and paired categorical variable was compared with McNemer test.

RESULTS

Mean ages (±SD; in years) of Groups A and B were 9.87 (2.7) and 9.82 (3.17), respectively, with median duration of illness of 12 months. At baseline, type, severity, and parameters (IBS-SSS) of IBS were equally distributed in 2 groups. There was a significant reduction in median interquartile range (IQR) of total IBS-SSS in psyllium versus placebo [75 (42.5-140) vs 225 (185-270); P < 0.001] at 4 weeks. Similarly 43.9% in Group A versus 9.7% in Group B attained remission [IBS-SSS < 75 ( P < 0.0001)]. The mean difference in IBS-SSS between Group A and Group B was -122.85 with risk ratio of 0.64 (95% CI; 0.42-0.83; P = 0.001) and absolute risk reduction of 32% (NNT = 3).

CONCLUSIONS

Psyllium husk is effective for the therapy of pediatric IBS when compared with placebo in short term.

A double-blind randomized clinical trial of Dracocephalum kotschyi Boiss. in the patients with diarrhea-predominant irritable bowel syndrome

Background and purpose

Irritable bowel syndrome (IBS) is a disease that shows its impacts on many populations worldwide. It is known as a functional disorder of the gastrointestinal tract followed by diarrhea and fecal inconsistency. Due to the lack of treatment in the allopathic medicine system for IBS, people in the western world use different herbs as alternative medicine. In the present study, we evaluated the dried extract of Dracocephalum kotschyi against IBS.

Experimental approach

In a randomized, double-blinded, placebo-controlled clinical trial, 76 diarrhea-predominant IBS patients were randomly assigned to two equal groups: the control group (given the placebo capsule containing 250 mg of dibasic calcium phosphate) and the treatment groups (given the capsule containing 75 mg of the dry extract of D. kotschyi and 175 mg of dibasic calcium phosphate as filler). The study was conducted based on Rome III criteria. We studied symptoms included in Rome III criteria and divided the study into the duration of drug administration and four weeks after drug administration. These groups were compared with those of the control group.

Findings/Results

Significant improvements were found in the quality of life, temperament, and IBS symptoms throughout the treatment duration. Quality of life, temperature, and IBS symptoms were slightly decreased in the treatment group 4 weeks after stopping the treatment. While concluding the study, we found D. kotschyi effective against IBS.

Conclusion and implications

Whole extract of D. kotschyi modulated symptoms of IBS patients and improved their quality of life.

Melatonin mediates mucosal immune cells, microbial metabolism, and rhythm crosstalk: A therapeutic target to reduce intestinal inflammation

Nowadays, melatonin, previously considered only as a pharmaceutical product for rhythm regulation and sleep aiding, has shown its potential as a co-adjuvant treatment in intestinal diseases, however, its mechanism is still not very clear. A firm connection between melatonin at a physiologically relevant concentration and the gut microbiota and inflammation has recently established. Herein, we summarize their crosstalk and focus on four novelties. First, how melatonin is synthesized and degraded in the gut and exerts potentially diverse phenotypic effects through its diverse metabolites. Second, how melatonin mediates the activation and proliferation of intestinal mucosal immune cells with paracrine and autocrine properties. By modulating T/B cells, mast cells, macrophages and dendritic cells, melatonin immunomodulatory involved in regulating T-cell differentiation, intervening T/B cell interaction and attenuating the production of pro-inflammatory factors, achieving its antioxidant action via specific receptors. Third, how melatonin exerts antimicrobial action and modulates microbial components, such as lipopolysaccharide, amyloid-β peptides via nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) or signal transducers and activators of transcription (STAT1) pathway to modulate intestinal immune function in immune-pineal axis. The last, how melatonin mediates the effect of intestinal bacterial activity signals on the body rhythm system through the NF-κB pathway and influences the mucosal epithelium oscillation via clock gene expression. These processes are achieved at mitochondrial and nuclear levels to control the host immune cell development. Considering unclear mechanisms and undiscovered actions of melatonin in gut-microbiome-immune axis, it's time to reveal them and provide new insight for the outlook of melatonin as a potential therapeutic target in the treatment and management of intestinal diseases.

Therapeutic potential of serotonin 4 receptor for chronic depression and its associated comorbidity in the gut

The latest estimates from world health organization suggest that more than 450 million people are suffering from depression and other psychiatric conditions. Of these, 50-60% have been reported to have progression of gut diseases. In the last two decades, researchers introduced incipient physiological roles for serotonin (5-HT) receptors (5-HTRs), suggesting their importance as a potential pharmacological target in various psychiatric and gut diseases. A growing body of evidence suggests that 5-HT systems affect the brain-gut axis in depressive patients, which leads to gut comorbidity. Recently, preclinical trials of 5-HT4R agonists and antagonists were promising as antipsychotic and prokinetic agents. In the current review, we address the possible pharmacological role and contribution of 5-HT4R in the pathophysiology of chronic depression and associated gut abnormalities. Physiologically, during depression episodes, centers of the sympathetic and parasympathetic nervous system couple together with neuroendocrine systems to alter the function of hypothalamic-pituitary-adrenal (HPA) axis and enteric nervous system (ENS), which in turn leads to onset of gastrointestinal tract (GIT) disorders. Consecutively, the ENS governs a broad spectrum of physiological activities of gut, such as visceral pain and motility. During the stages of emotional stress, hyperactivity of the HPA axis alters the ENS response to physiological and noxious stimuli. Consecutively, stress-induced flare, swelling, hyperalgesia and altered reflexes in gut eventually lead to GIT disorders. In summary, the current review provides prospective information about the role and mechanism of 5-HT4R-based therapeutics for the treatment of depressive disorder and possible consequences for the gut via brain-gut axis interactions. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Probiotic treatment induced change of inflammation related metabolites in IBS-D patients/double-blind, randomized, placebo-controlled trial

There have been many studies suggesting that probiotics are effective in patients with diarrhea-predominant irritable bowel syndrome (IBS-D). However, its mechanism of action as well as prediction of response is still to be elucidated. In the present study, to find out metabolomic characteristics of probiotic effect in IBS-D, we compared IBS symptom changes and metabolomic characteristics in the subjects' urine samples between multi-strain probiotics (one strain of Lactobacillus sp. and four strains of Bifidobacterium sp.) group (n = 32) and placebo group (n = 31). After 8 weeks' administration (3 times/day), dissatisfaction in bowel habits and stool frequencies were significantly improved. Also, probiotics group had significantly changed seven metabolites including palmitic acid methyl ester (PAME) and 4,6-dihydroxyquinoline, 4-(2-aminophenyl)-2,4-dioxobutanoic acid (DOBA). According to IBS-SSS and IBS-QoL questionnaires, IBS-SSS responders showed higher PAME levels and IBS-QoL responders showed lower DOBA levels. This suggests potential role of these metabolites as a biomarker to predict probiotics effect in IBS-D patients.

Aminophylline suppresses stress-induced visceral hypersensitivity and defecation in irritable bowel syndrome

Pharmacological therapy for irritable bowel syndrome (IBS) has not been established. In order to find candidate drugs for IBS with diarrhea (IBS-D), we screened a compound library of drugs clinically used for their ability to prevent stress-induced defecation and visceral hypersensitivity in rats. We selected the bronchodilator aminophylline from this library. Using a specific inhibitor for each subtype of adenosine receptors (ARs) and phosphodiesterases (PDEs), we found that both A2BARs and PDE4 are probably mediated the inhibitory effect of aminophylline on wrap restraint stress (WRS)-induced defecation. Aminophylline suppressed maternal separation- and acetic acid administration-induced visceral hypersensitivity to colorectal distension (CRD), which was mediated by both A2AARs and A2BARs. We propose that aminophylline is a candidate drug for IBS-D because of its efficacy in both of stress-induced defecation and visceral hypersensitivity, as we observed here, and because it is clinically safe.

Melatonin's role as a co-adjuvant treatment in colonic diseases: A review

Melatonin is produced in the pineal gland as well as many other organs, including the enterochromaffin cells of the digestive mucosa. Melatonin is a powerful antioxidant that resists oxidative stress due to its capacity to directly scavenge reactive species, to modulate the antioxidant defense system by increasing the activities of antioxidant enzymes, and to stimulate the innate immune response through its direct and indirect actions. In addition, the dysregulation of the circadian system is observed to be related with alterations in colonic motility and cell disruptions due to the modifications of clock genes expression. In the gastrointestinal tract, the activities of melatonin are mediated by melatonin receptors (MT2), serotonin (5-HT), and cholecystokinin B (CCK2) receptors and via receptor-independent processes. The levels of melatonin in the gastrointestinal tract exceed by 10-100 times the blood concentrations. Also, there is an estimated 400 times more melatonin in the gut than in the pineal gland. Gut melatonin secretion is suggested to be influenced by the food intake. Low dose melatonin treatment accelerates intestinal transit time whereas high doses may decrease gut motility. Melatonin has been studied as a co-adjuvant treatment in several gastrointestinal diseases including irritable bowel syndrome (IBS), constipation-predominant IBS (IBS-C), diarrhea-predominant IBS (IBS-D), Crohn's disease, ulcerative colitis, and necrotizing enterocolitis. The purpose of this review is to provide information regarding the potential benefits of melatonin as a co-adjuvant treatment in gastrointestinal diseases, especially IBS, Crohn's disease, ulcerative colitis, and necrotizing enterocolitis.

Rifaximin and eluxadoline - newly approved treatments for diarrhea-predominant irritable bowel syndrome: what is their role in clinical practice alongside alosetron?

INTRODUCTION

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a common functional gastrointestinal condition in which patients experience abdominal pain, diarrhea, bloating, cramps, flatulence, fecal urgency, and incontinence.

AREAS COVERED

We review two recently approved therapies that focus on treating underlying pathogenic mechanisms of IBS-D: (1) the non-absorbable antibiotic rifaximin, and (2) the opioid receptor agonist/antagonist eluxadoline. We compare the safety and efficacy data emerging from rifaximin and eluxadoline registration trials with safety and efficacy data from the alosetron clinical development program.

EXPERT OPINION

The rifaximin and eluxadoline clinical development programs for IBS-D have demonstrated significant improvement in IBS-D endpoints compared to placebo. Direct comparison of primary endpoint results from the alosetron, rifaximin, and eluxadoline pivotal trials is not possible; however, general estimates of efficacy can be made, and these demonstrate similar and significantly greater responses to 'adequate relief' and a composite endpoint of abdominal pain/stool form for each agent compared to placebo. With the recent approval in the United States of rifaximin and eluxadoline for IBS-D, how should clinicians employ these agents? We suggest that they be utilized sequentially, taking into consideration patient symptoms and severity, prior medical history, mode of action, cost, availability, managed care coverage, and adverse event profiles.

Prevalence of irritable bowel syndrome in caregivers of patients with chronic diseases

BACKGROUND

Caregivers are an at-risk population for psychic and physical diseases such as irritable bowel syndrome (IBS). However, it is not known whether providing care for the chronically ill patient can be considered a risk factor for developing IBS. In this study, our aim was to evaluate the prevalence of IBS according to the Rome II criteria in a group of caregivers.

METHODS

A cross-sectional study was conducted through an evaluation of caregivers of chronically ill patients. Subjects completed questionnaires including the Rome II Modular Questionnaire, the Hospital Anxiety and Depression Scale, the Zarit Caregiver Burden Interview (ZCBI) (an instrument for evaluating the burden experienced by caregivers), and the irritable bowel syndrome quality of life (IBS-QoL) questionnaire.

KEY RESULTS

Ninety-six primary caregivers (mean age was 43.6 ± 13.7 years and 87% were women) were evaluated. The mean length of time providing care was 37.6 months (3-288 months). Forty-seven caregivers (49%) presented with IBS. The caregivers with IBS had higher scores in the global ZCBI score (47 ± 8 vs 28 ± 8, p = 0.001) and on the anxiety and depression scale (p = 0.001) than those that did not have IBS. A total of 72% were diagnosed with caregiver stress syndrome; 42 of them had IBS according to the Rome II questionnaire (60% vs 18%, p = 0.001, relative risk 3.28, 95% CI: 1.4-7.4).

CONCLUSIONS & INFERENCES

Caregivers of chronically ill patients have a high prevalence of IBS, which is associated with depression, anxiety, and poor QoL.

Molecular and functional diversity of GABA-A receptors in the enteric nervous system of the mouse colon

The enteric nervous system (ENS) provides the intrinsic neural control of the gastrointestinal tract (GIT) and regulates virtually all GI functions. Altered neuronal activity within the ENS underlies various GI disorders with stress being a key contributing factor. Thus, elucidating the expression and function of the neurotransmitter systems, which determine neuronal excitability within the ENS, such as the GABA-GABAA receptor (GABAAR) system, could reveal novel therapeutic targets for such GI disorders. Molecular and functionally diverse GABAARs modulate rapid GABAergic-mediated regulation of neuronal excitability throughout the nervous system. However, the cellular and subcellular GABAAR subunit expression patterns within neurochemically defined cellular circuits of the mouse ENS, together with the functional contribution of GABAAR subtypes to GI contractility remains to be determined. Immunohistochemical analyses revealed that immunoreactivity for the GABAAR gamma (γ) 2 and alphas (α) 1, 2, 3 subunits was located on somatodendritic surfaces of neurochemically distinct myenteric plexus neurons, while being on axonal compartments of submucosal plexus neurons. In contrast, immunoreactivity for the α4-5 subunits was only detected in myenteric plexus neurons. Furthermore, α-γ2 subunit immunoreactivity was located on non-neuronal interstitial cells of Cajal. In organ bath studies, GABAAR subtype-specific ligands had contrasting effects on the force and frequency of spontaneous colonic longitudinal smooth muscle contractions. Finally, enhancement of γ2-GABAAR function with alprazolam reversed the stress-induced increase in the force of spontaneous colonic contractions. The study demonstrates the molecular and functional diversity of the GABAAR system within the mouse colon providing a framework for developing GABAAR-based therapeutics in GI disorders.

Melatonin for the treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common disorder characterized by recurrent abdominal pain or discomfort, in combination with disturbed bowel habits in the absence of identifiable organic cause. Melatonin (N-acetyl-5-methoxytryptamine) is a hormone produced by the pineal gland and also large number by enterochromaffin cells of the digestive mucosa. Melatonin plays an important part in gastrointestinal physiology which includes regulation of gastrointestinal motility, local anti-inflammatory reaction as well as moderation of visceral sensation. Melatonin is commonly given orally. It is categorized by the United States Food and Drug Administration as a dietary supplement. Melatonin treatment has an extremely wide margin of safety though it may cause minor adverse effects, such as headache, rash and nightmares. Melatonin was touted as a potential effective candidate for IBS treatment. Putative role of melatonin in IBS treatment include analgesic effects, regulator of gastrointestinal motility and sensation to sleep promoter. Placebo-controlled studies in melatonin suffered from heterogeneity in methodology. Most studies utilized 3 mg at bedtime as the standard dose of trial. However, all studies had consistently showed improvement in abdominal pain, some showed improvement in quality of life of IBS patients. Melatonin is a relatively safe drug that possesses potential in treating IBS. Future studies should focus on melatonin effect on gut mobility as well as its central nervous system effect to elucidate its role in IBS patients.

Pathophysiology and pharmacotherapy of gastroparesis: current and future perspectives

INTRODUCTION

Gastroparesis is an important clinical disorder characterised by delayed gastric emptying in the absence of mechanical outlet obstruction. Idiopathic, diabetes and postsurgical causes represent the most common aetiologies. The condition commonly manifests as upper gastrointestinal symptoms, including nausea, vomiting, postprandial fullness, early satiety, abdominal pain and bloating.

AREAS COVERED

This paper provides a review of the prevalence, pathophysiology and clinical features associated with gastroparesis, with a particular focus on current pharmacological management options and novel and emerging therapies. A literature search was undertaken using the search terms: gastroparesis, diabetic gastroparesis, idiopathic gastroparesis, gastric emptying, prokinetic, metoclopramide, domperidone, erythromycin, motilin, alemcinal, KC11458, mitemcinal, ghrelin, TZP-101, TZP-102, RM-131, tegaserod, prucalopride, naronapride, velusetrag, levosulpiride, itopride, botulinum toxin, gastric electrical stimulation, Enterra.

EXPERT OPINION

Strategies for the management of gastroparesis include correction of malnutrition, dehydration and electrolyte imbalance, relief of symptoms by appropriate use of prokinetic and antiemetic agents and, in patients with gastroparesis associated with diabetes or critical illness-induced hyperglycaemia, optimisation of glycaemic control. Conventional prokinetic agents form the mainstay of treatment. While novel pharmacotherapies are in development, compelling evidence for their efficacy, particularly in symptom relief, remains to be established.

IL-17/IFN-γ interactions regulate intestinal inflammation in TNBS-induced acute colitis

Colonic administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) induced acute colitis in mice and elicited a Th1 immune response. Th17 cells are believed to play a major role in TNBS-induced colitis. The aim of this study is to investigate the roles of interleukin (IL)-17 and interferon (IFN)-γ in the pathogenesis of TNBS-induced acute colitis. We assessed the inflammation scores of TNBS-induced acute colitis in wild-type (WT), IL-17 knockout (KO), and IFN-γ KO mice and measured the levels of inflammatory cytokines using real-time PCR and ELISAs. Histology data showed that IL-17 KO mice with TNBS-induced colitis had significantly lower neutrophil infiltration and inflammatory macroscopic scores compared to the IFN-γ KO mice and WT mice. Intraperitoneal injection of anti-IL-17 monoclonal antibody confirmed a specific role for IL-17 in TNBS-induced acute colitis in the 3 strains of mice. The severity of colitis was higher in IFN-γ KO mice and lower in IL-17 KO mice compared to WT mice. Our data suggested that IL-17 signaling plays a critical role in the local inflammation of TNBS-induced colitis, while IFN-γ was not an important mediator of the local inflammation response. IL-17 may represent a target for therapeutic intervention in inflammatory bowel disease patients.

Effects of β-(1,3-1,6)-D-glucan on irritable bowel syndrome-related colonic hypersensitivity

Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by chronic abdominal pain associated with altered bowel habits. Since the prevalence of IBS is very high and thus, involves elevated health-care costs, treatment of this condition by methods other than prescribed medicines could be beneficial. β-(1,3)-D-glucan with β-(1,6) branches (β-glucan) has been used as a nutritional supplement for many years. In this study, we examined the effect of β-glucan on fecal pellet output and visceral pain response in animal models of IBS. Oral administration of β-glucan suppressed the restraint stress- or drug-induced fecal pellet output. β-Glucan also suppressed the visceral pain response to colorectal distension. These results suggest that β-glucan could be beneficial for the treatment and prevention of IBS.

Functional gastrointestinal disorders in inflammatory bowel disease: impact on quality of life and psychological status

BACKGROUND AND AIM

In inflammatory bowel disease (IBD), ongoing gastrointestinal (GI) symptoms consistent with coexistent functional GI disorders (FGID) might occur. It is uncertain what effect these symptoms have on health-related quality of life (HRQoL) and psychological comorbidity. The aim of the present study was to identify interrelationships among IBD, symptoms consistent with FGID, HRQoL, and psychological comorbidity.

METHODS

A total of 256 consecutive IBD patients had diagnoses and disease activity verified at case-note review. Patients completed a contemporaneous survey assessing HRQoL, anxiety/depression, and GI symptoms (classified by Rome III criteria).

RESULTS

Of 162 respondents (response rate: 63%), 95 (58.6%) had Crohn's disease and 63 (38.8%) had ulcerative colitis. By Rome III criteria, 66% met criteria for at least one FGID. Those with significant (Hospital Anxiety and Depression Scale ≥ 8) anxiety and/or depression were more likely to meet criteria for coexistent FGID (78% vs 22% and 89% vs 11%, respectively; each P < 0.001). A "load effect" was noted, such that the number of symptoms consistent with FGID in each patient correlated positively with anxiety and depression and negatively with HRQoL. Symptoms of any coexistent FGID were highly prevalent, even in those with currently-inactive IBD (57%).

CONCLUSIONS

Symptoms consistent with FGID are highly prevalent in IBD and correlate with greater psychological comorbidity and poorer HRQoL in a "load-dependent" fashion. Therapy directed either at symptom load or psychological comorbidity might independently improve HRQoL in IBD.

Rifaximin therapy for patients with irritable bowel syndrome without constipation

BACKGROUND

Evidence suggests that gut flora may play an important role in the pathophysiology of the irritable bowel syndrome (IBS). We evaluated rifaximin, a minimally absorbed antibiotic, as treatment for IBS.

METHODS

In two identically designed, phase 3, double-blind, placebo-controlled trials (TARGET 1 and TARGET 2), patients who had IBS without constipation were randomly assigned to either rifaximin at a dose of 550 mg or placebo, three times daily for 2 weeks, and were followed for an additional 10 weeks. The primary end point, the proportion of patients who had adequate relief of global IBS symptoms, and the key secondary end point, the proportion of patients who had adequate relief of IBS-related bloating, were assessed weekly. Adequate relief was defined as self-reported relief of symptoms for at least 2 of the first 4 weeks after treatment. Other secondary end points included the percentage of patients who had a response to treatment as assessed by daily self-ratings of global IBS symptoms and individual symptoms of bloating, abdominal pain, and stool consistency during the 4 weeks after treatment and during the entire 3 months of the study.

RESULTS

Significantly more patients in the rifaximin group than in the placebo group had adequate relief of global IBS symptoms during the first 4 weeks after treatment (40.8% vs. 31.2%, P=0.01, in TARGET 1; 40.6% vs. 32.2%, P=0.03, in TARGET 2; 40.7% vs. 31.7%, P<0.001, in the two studies combined). Similarly, more patients in the rifaximin group than in the placebo group had adequate relief of bloating (39.5% vs. 28.7%, P=0.005, in TARGET 1; 41.0% vs. 31.9%, P=0.02, in TARGET 2; 40.2% vs. 30.3%, P<0.001, in the two studies combined). In addition, significantly more patients in the rifaximin group had a response to treatment as assessed by daily ratings of IBS symptoms, bloating, abdominal pain, and stool consistency. The incidence of adverse events was similar in the two groups.

CONCLUSIONS

Among patients who had IBS without constipation, treatment with rifaximin for 2 weeks provided significant relief of IBS symptoms, bloating, abdominal pain, and loose or watery stools. (Funded by Salix Pharmaceuticals; ClinicalTrials.gov numbers, NCT00731679 and NCT00724126.).

An Evidence-based Approach to Therapy in IBS-D: A Case Study Compendium

A burden on both patients and the healthcare system, irritable bowel syndrome (IBS) is a prevalent condition that can result in high medical costs, frequent visits to the doctor, missed work, and anxiety and depression in the patient. This chronic disorder causes abdominal pain or discomfort and is characterized by abnormal defecation that presents mainly as either constipation or diarrhea symptoms. IBS associated with diarrhea (IBS-D) accounts for approximately one third of all IBS patients. IBS-D treatment can be confusing and frustrating for both the patient and the physician, complicated by the fact that a specific therapeutic algorithm has not been developed. Treatment options are widely varied, consisting of both nonpharmacologic (dietary changes) and pharmacologic (loperamide and alosetron) interventions. Furthermore, mounting evidence suggests a possible role for small intestinal bacterial overgrowth in the pathogenesis of IBS-D; thus, both antibiotics (such as rifaximin) and probiotics are frequently used to treat patients. Although all of these interventions elicit some measure of symptom response in a proportion of treated patients, there is no standard of care for the treatment of IBS-D. Thus, physicians would benefit from knowledge of all of the strategies used to treat IBS-D, in order to treat patients appropriately.

Opioid-induced latent sensitization in a model of non-inflammatory viscerosomatic hypersensitivity

Exposure to opioids can induce a state of "latent sensitization" characterized by long-lasting enhanced responses to subsequent cutaneous injury. Here, we explored the possibility that prior treatment with morphine could induce a state of latent sensitization to visceral pain conditions. Following butyrate enemas to induce non-inflammatory visceral pain, acute morphine administration produced dose-related inhibition of referred viscerosomatic hypersensitivity. Treatment with morphine for a period of six days resulted in a persistent hyperalgesia that resolved many days after termination of drug administration. In morphine pre-exposed rats, butyrate-induced referred hypersensitivity was enhanced and extended in duration. No differences were observed in the morphine dose-response curve in suppression of acute nociception (i.e., the hot-plate assay) when morphine pre-exposed rats were compared to naïve rats indicating that opioid antinociceptive tolerance was not present. However, the morphine dose-response curve to suppress evoked viscerosomatic hypersensitivity was displaced to the right by approximately 4-fold in morphine pre-exposed rats. Induction of viscerosomatic hypersensitivity resulted in an increased labeling of CGRP-, but not substance P-positive cells in the lumbar dorsal root ganglia; increased labeling was not affected by prior exposure to morphine. The data indicate that a period of morphine exposure can induce a state of "latent sensitization" to subsequent visceral pain characterized by extended duration of hypersensitivity. This condition likely reflects enhanced visceral "pain" intensity as a consequence of persistent pronociceptive adaptive changes.

Bacteria, genetics and irritable bowel syndrome

EVALUATION OF: Villani AC, Lemire M, Thabane M et al. Genetic risk factors for post-infectious irritable bowel syndrome following a waterborne outbreak of gastroenteritis. Gastroenterology 138, 1502-1513 (2010). While the pathogenesis of irritable bowel syndrome (IBS) remains to be fully defined, two clinical observations - the occurrence, de novo, of IBS following bacterial gastroenteritis and the history, commonly obtained from IBS patients, of other instances of the syndrome within their families - have instigated investigations, in IBS, of the potential roles, on the one hand, of the gut microbiota and the host response and, on the other hand, of genetic factors. The study reviewed here relates to both of these factors by studying genetic predisposition to postinfective IBS in a large population of individuals who were exposed to a multimicrobial enteric infection, which resulted in a severe outbreak of gastroenteritis and was followed by the development of IBS in over a third. In this detailed study, the investigators identified a number of genes that were linked significantly to the development of postinfectious-IBS in the Toll-like receptor 9, IL-6 and cadherin 1 regions. These genes play important roles in bacterial recognition, the inflammatory response and epithelial integrity, respectively, and provide considerable support for the hypothesis that links IBS onset to disturbances in the microbiota and the host response.

Probiotic treatment of irritable bowel syndrome in children

Treatment of functional bowel disorders of irritable bowel-type (IBS) in children remains a difficult task because of a lack of drugs with low adverse event profile. We here report the results of a treatment study in 203 children (66 boys and 137 girls) age 4 to 18 years (mean: 10.5+/-4.5 years) with typical IBS symptoms with abdominal pain and either predominant diarrhea (n=50), constipation (n=56), alternating stool frequency (n=28) or unspecific pain (n=69). The average duration of symptoms prior to therapy was 175 days. Most (95%) patients up to age 11 were treated with a daily dose of 10 drops of Symbioflor 2 (SF2) (SymbioPharm, Herborn) (cells and autolysate of 1.5-4.5x10(7) CFU of bacteria of Escherichia coli type), in the elder children 77% received this dosage, while the remaining received a higher dose up to 30 drops/day. Treatment lasted 43 days on average.

RESULTS

All patients tolerated the treatment well and without adverse events. The key IBS symptoms (abdominal pain, stool frequency) as well as the other symptoms (bloating, mucous and blood in stool, need for straining at stools, urge to defecate) improved significantly during treatment. Global assessment of therapy by parents and doctors was altogether positive. In summary these data confirm efficacy and tolerability of this probiotic compound in children and adolescents and supplement published data of probiotic IBS therapy in adults.

[Brain-gut axis dysfunction]

There is a bidirectional relation between the central nervous system and the digestive tract, i.e., the brain-gut axis. Numerous data argue for a dysfunction of the brain-gut axis in the pathophysiology of irritable bowel syndrome (IBS). Visceral hypersensitivity is a marker of IBS as well as of an abnormality of the brain-gut axis. This visceral hypersensitivity is peripheral and/or central in origin and may be the consequence of digestive inflammation or an anomaly of the nociceptive message treatment at the spinal and/or supraspinal level. Stress is involved in the genesis and maintenance of IBS. Disturbances of the autonomic nervous system are observed in IBS as a consequence of brain-gut axis dysfunction. The contribution of the neurosciences, in particular brain imaging techniques, has contributed to the better understanding of IBS physiopathology. The better knowledge of brain-gut axis dysfunction has therapeutic implications, either through drugs and/or cognitive and behavioral therapies.

Clinical trial: the glucagon-like peptide-1 analogue ROSE-010 for management of acute pain in patients with irritable bowel syndrome: a randomized, placebo-controlled, double-blind study

BACKGROUND

There is currently no treatment available to manage acute pain attacks in IBS patients regardless of subtype.

AIMS

To evaluate efficacy and safety of the GLP-1 analogue ROSE-010 in patients with irritable bowel syndrome (IBS) through a randomized, double-blind, placebo-controlled study.

METHODS

Eligible patients (n = 166) meeting Rome II criteria were randomly assigned to receive single subcutaneous injections of ROSE-010 100 microg, 300 microg and placebo in a cross-over design. Safety was assessed from spontaneously reported adverse events and measurement of vital signs. Patient-rated pain relief and intensity were measured on a 100-mm visual analogue scale. The primary efficacy variable was proportion of patients with >50% maximum total pain relief response from 10 to 60 min after treatment. Secondary endpoints included the maximum summed pain intensity difference, time to meaningful pain relief and patient ratings of satisfaction with treatment.

RESULTS

Twice as many patients were responders in the primary efficacy endpoint after both ROSE-010 injections compared to placebo (24%P = 0.011, 23%P = 0.005, and 12% after 300 microg, 100 microg and placebo injections, respectively). Similar results were obtained for the proportion of patients with total pain intensity response. Times to meaningful and total pain relief were shorter for both doses of ROSE-010 compared with placebo. Compared with placebo, more patients (P < 0.05) were satisfied with ROSE-010 and considered ROSE-010 better than previous IBS medications used.

CONCLUSION

ROSE-010 was well tolerated and provided fast and effective relief of acute pain attacks on demand in IBS patients.

State-of-the-art of irritable bowel syndrome and inflammatory bowel disease research in 2008

Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) are two of the leading causes of chronic intestinal conditions in the world. This issue of World Journal of Gastroenterology (WJG) presents a series of papers from world experts who discuss the current knowledge and opinions on these important conditions. Although great strides have been made in the diagnosis, treatment and pathology of IBS and IBD; much has yet to be explained. The etiologies and risk factors of these multifactorial conditions remain elusive. Specific diagnostic biomarkers need to be developed and safer treatments developed. The burden of IBS and IBD on the healthcare system is felt with repeated medical care visits and high costs. IBS and IBD patients can account for 30%-50% of office visits at gastroenterology services/clinics. Over one million people have IBD in the United States, with 30 000 new cases being diagnosed every year. One-quarter million people in the UK are afflicted with IBD. The cost of medical care in the United States for IBD is estimated to be $1.8 billion/year.