Functional findings in irritable bowel syndrome

A systematic review of the association between environmental risk factors and the development of irritable bowel syndrome

BACKGROUND AND AIM

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder with roots in genetic, immune, psychological, and dietary factors. Recently, the potential correlation between environmental exposures, such as air pollution, and IBS has gained attention. This review aimed to systematically examine existing studies on environmental factors associated with IBS, elucidating this interplay and guiding future research.

METHODS

A literature search was conducted in Medline, EMBASE, Scopus, and Cochrane databases from database inception to October 10, 2023, using the keywords "Irritable Bowel" or IBS or "Irritable Colon" or "Mucous Colitis" or "Spastic Colitis" or "Spastic Colon" AND "environment* exposure*". Studies were included if they were original, published in English, described defined environmental exposure(s), and had documented diagnosis of IBS. For the purposes of this review, articles reporting physical (e.g. radiation and climate change), biological (e.g. bacteria and viruses), and chemical (e.g. harmful gases) exposures were included while psychological and dietary factors, which have been reviewed in detail elsewhere, are outside of the scope.

RESULTS

A total of seven studies focusing on air quality, microbial exposure, and other environmental factors were reviewed. Studies highlighted a potential association between air pollutants and increased IBS incidence. Microbial exposure, post-natural disaster or due to poor sanitation, was linked to IBS development and gut dysbiosis. Other exposures, such as early pet ownership, were also associated with IBS risk.

CONCLUSION

Existing research demonstrates an epidemiologic relationship between environmental exposures and the development of IBS. Further research is needed to understand these associations.

The Latest Data Concerning the Etiology and Pathogenesis of Irritable Bowel Syndrome

Globally, irritable bowel syndrome (IBS) is present in approximately 10% of the population. While this condition does not pose a risk of complications, it has a substantial impact on the patient's quality of life. Moreover, this disease has a significant financial impact on healthcare systems. This includes the direct costs associated with the diagnosis and treatment of these patients, as well as the indirect costs that arise from work absenteeism and reduced productivity. In light of these data, recent research has focused on elucidating the pathophysiological basis of this condition in order to improve the quality of life for affected individuals. Despite extensive research to date, we still do not fully understand the precise mechanisms underlying IBS. Numerous studies have demonstrated the involvement of the gut-brain axis, visceral hypersensitivity, gastrointestinal dysmotility, gut microbiota dysbiosis, food allergies and intolerances, low-grade mucosal inflammation, genetic factors, and psychosocial factors. The acquisition of new data is crucial for the advancement of optimal therapeutic approaches aimed at enhancing the general health of these patients while simultaneously reducing the financial burden associated with this ailment.

A Narrative Review on the Viability of Osteopathic Manipulative Medicine in Treating Irritable Bowel Syndrome With Constipation (IBS-C)

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by chronic abdominal pain and alterations in bowel habits, with global prevalence. The etiology of the disease is likely multifactorial; however, autonomic nervous system (ANS) dysfunction and immune-mediated inflammation may contribute the most to the hallmark symptoms of abdominal pain and altered motility of the gut. Current pharmacological therapies operate to modulate intestinal transit, alter the composition of the gut flora and control pain. Non-pharmacological approaches include dietary changes, increased physical activity, or fecal microbiota transplants. None of these therapies can modulate ANS dysfunction or impact the underlying inflammation that is likely perpetuating the symptoms of IBS. Osteopathic Manipulative Medicine (OMM) is a clinical approach focused on physical manipulation of the body's soft tissues to correct somatic dysfunctions. OMM can directly target the pathophysiology of IBS through many approaches such as ANS modulation and lymphatic techniques to modify the inflammatory mechanisms within the body. Particular OMM techniques of use are lymphatic manipulation, myofascial release, sympathetic ganglia treatment, sacral rocking, counterstrain, and viscerosomatic treatment. The aim of this study is to identify OMM treatments that can be used to potentially reduce the inflammation and ANS dysfunction associated with IBS symptoms, thereby providing a new non-pharmacological targeted approach for treating the disease.

Comparison of the Effectiveness of Mindfulness-Based Stress Reduction and Compassion-Focused Treatment on the Severity of Gastrointestinal Symptoms in Patients with Irritable Bowel Syndrome

Background

The aim of this research was to compare the effectiveness of mindfulness-based stress reduction and compassion-focused on the severity of digestive symptoms in patients with irritable bowel syndrome (IBS).

Methods

The research method was of semi-experimental type with pre-test, post-test, follow-up, and experimental and control groups. The population included patients with IBS in Isfahan city, 45 of them were selected by convenience sampling method and randomly assigned to three groups (15 in each group). Then, the patients of one experimental group received eight sessions of 90 minutes of a mindfulness-based stress reduction program, while the other experimental group received eight sessions of 90 minutes of compassion-focused therapy. The measurement tools included the severity of IBS scale and a short clinical interview. Research data were analyzed using variance analysis with repeated measures on one factor (mixed design).

Results

The results showed that both methods of intervention had been equally effective on the severity of disease symptoms (P<0.01).

Conclusion

Both intervention methods can be used as a complementary treatment for patients with IBS.

The critical role of gut-brain axis microbiome in mental disorders

The Gut-brain axis is a bidirectional neural and humoral signaling that plays an important role in mental disorders and intestinal health and connects them as well. Over the past decades, the gut microbiota has been explored as an important part of the gastrointestinal tract that plays a crucial role in the regulation of most functions of various human organs. The evidence shows several mediators such as short-chain fatty acids, peptides, and neurotransmitters that are produced by the gut may affect the brain's function directly or indirectly. Thus, dysregulation in this microbiome community can give rise to several diseases such as Parkinson's disease, depression, irritable bowel syndrome, and Alzheimer's disease. So, the interactions between the gut and the brain are significantly considered, and also it provides a prominent subject to investigate the causes of some diseases. In this article, we reviewed and focused on the role of the largest and most repetitive bacterial community and their relevance with some diseases that they have mentioned previously.

Ethanol Extract of Mao Jian Green Tea Attenuates Gastrointestinal Symptoms in a Rat Model of Irritable Bowel Syndrome with Constipation via the 5-hydroxytryptamine Signaling Pathway

In a previous study, we demonstrated that the hydro extract of Mao Jian Green Tea (MJGT) promotes gastrointestinal motility. In this study, the effect of MJGT ethanol extract (MJGT_EE) in treating irritable bowel syndrome with constipation (IBS-C) in a rat model constructed via maternal separation combined with an ice water stimulation was investigated. First, a successful model construction was confirmed through the determination of the fecal water content (FWC) and the smallest colorectal distension (CRD) volume. Then, the overall regulatory effects of MJGT_EE on the gastrointestinal tract were preliminarily evaluated through gastric emptying and small intestinal propulsion tests. Our findings indicated that MJGT_EE significantly increased FWC (p < 0.01) and the smallest CRD volume (p < 0.05) and promoted gastric emptying and small intestinal propulsion (p < 0.01). Furthermore, mechanistically, MJGT_EE reduced intestinal sensitivity by regulating the expression of proteins related to the serotonin (5-hydroxytryptamine; 5-HT) pathway. More specifically, it decreased tryptophan hydroxylase (TPH) expression (p < 0.05) and increased serotonin transporter (SERT) expression (p < 0.05), thereby decreasing 5-HT secretion (p < 0.01), activating the calmodulin (CaM)/myosin light chain kinase (MLCK) pathway, and increasing 5-HT₄ receptor (5-HT₄R) expression (p < 0.05). Moreover, MJGT_EE enhanced the diversity of gut microbiota, increased the proportion of beneficial bacteria, and regulated the number of 5-HT-related bacteria. Flavonoids may play the role of being active ingredients in MJGT_EE. These findings suggest that MJGT_EE could serve as a potential therapeutic pathway for IBS-C.

Impact of intestinal disorders on central and peripheral nervous system diseases

Brain injuries and neurological diseases have a significant impact on the gut microbiome and the gut barrier. Reciprocally, gut disorders, such as Inflammatory Bowel Syndromes (IBS), can affect the development and pathology of neurodegenerative and neuropsychiatric diseases, although this aspect is less well studied and is the focus of this review. Inflammatory Bowel Syndrome (IBS) is a chronic and debilitating functional gastrointestinal disorder afflicting an estimated 9-23% of the world's population. A hallmark of this disease is leaky gut, a pathology in which the integrity of the gut blood barrier is compromised, causing gut contents such as immune cells and microbiota to enter the bloodstream leading to low-grade systemic inflammation. The increased levels of inflammation associated cytokines in circulation has the potential to affect all organs, including the brain. Although the brain is protected by the blood brain barrier, inflammation associated cytokines can damage the junctions in this barrier and allow brain infiltration of peripheral immune cells. Central inflammation in the brain is associated with various neurodegenerative disease such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, and neuropsychiatric disorders, namely, depression, and anxiety. Neurodegenerative diseases are of particular concern due to the anticipated rise in the population of the elderly and consequently, the prevalence of these diseases. Additionally, depression and anxiety are the most common mental illnesses affecting roughly 18% of the American population. In this review, we will explore the mechanisms by which IBS can influence the risk and severity of neurological disease.

Different clinical symptom patterns in patients with reflux micro-aspiration

Background

Pulmonary manifestation of gastro-oesophageal reflux disease (GORD) is a well-recognised entity; however, little primary reported data exists on presenting symptoms of patients in whom reflux micro-aspiration is confirmed. The aim of this study is to report symptoms and presenting patterns of a large group of patients with confirmed reflux micro-aspiration.

Patients and methods

Data was extracted from a prospectively populated database of patients referred to a tertiary specialist centre with severe, refractory or atypical reflux. Patients with reflux micro-aspiration on scintigraphy were included in this study. A separate group included patients with evidence of proximal reflux to the level of pharynx when supine and/or upright.

Results

Inclusion criteria were met by 243 patients with confirmed reflux micro-aspiration (33% males; mean age 59). Most common symptoms amongst patients with micro-aspiration were regurgitation (72%), cough (67%), heartburn (66%), throat clearing (65%) and dysphonia (53%). The most common two-symptom combinations were heartburn/regurgitation, cough/throat clearing, regurgitation/throat clearing, cough/regurgitation and dysphonia/throat clearing. The most common three-symptom combinations were cough/heartburn/regurgitation, cough/regurgitation/throat clearing and dysphonia/regurgitation/throat clearing. Cluster analysis demonstrated two main symptom groupings, one suggestive of proximal volume reflux symptoms and the other with motility/inflammatory bowel syndrome-like symptoms (bloat, constipation).

Conclusion

The combination of typical symptoms of GORD such as heartburn or regurgitation and a respiratory or upper aero-digestive complaint such as cough, throat clearing or voice change should prompt consideration of reflux micro-aspiration.

Patients with reflux micro-aspiration most commonly present with a combination of regurgitation and/or heartburn and cough and/or throat clearinghttps://bit.ly/3GM8cNS

Increased incidence and recurrence rates of acute diverticulitis in patients with irritable bowel syndrome

AIM

Acute diverticulitis (AD) is commonly diagnosed in outpatient and emergency departments and is associated with severe complications such as perforation and fistula. Symptoms of irritable bowel syndrome (IBS), such as abdominal pain, constipation and diarrhoea, are also common with AD. This study aimed to evaluate the strength of a possible association between IBS and AD.

METHOD

This retrospective study analysed records from Taiwan's National Health Insurance Research Database and involved a total of 25 810 patients, including 12 905 IBS patients diagnosed between 2000 and 2012. The IBS and non-IBS cohorts were matched by propensity score for age, gender, comorbidities and medication, then compared for confounding variables by the chi-square test or Student's t-test. The association between AD and IBS was determined using Cox proportional hazards models. Kaplan-Meier curves assessed the cumulative incidence of AD in IBS patients.

RESULTS

The overall incidence of AD was 3.95-fold higher in the IBS cohort than in the non-IBS cohort (63.34 vs 16.02 per 100 000 person-years, respectively) and IBS was an independent risk factor for subsequent diagnosis of AD in multivariate Cox proportional hazards regression model adjusted hazards ratio (aHR = 3.84, 95% CI = 2.29-6.44, P < 0.001) and Kaplan-Meier (log-rank test, P < 0.001) analysis. IBS was also associated with a high recurrence rate of AD (aHR = 8.30, 95% CI = 1.07-64.30, P = 0.04).

CONCLUSION

The epidemiological evidence in this study demonstrates that patients with IBS are associated with a higher incidence of AD and also its recurrence.

Is there a causal link between psychological disorders and functional gastrointestinal disorders?

INTRODUCTION

Psychological distress is associated with functional gastrointestinal disorders (FGIDs) including irritable bowel syndrome (IBS) and functional dyspepsia (FD) but only evidence from prospective longitudinal and treatment studies can indicate whether the link between FGIDs and psychological distress is causal. Emerging evidence suggests underlying biological mechanisms may explain the association of psychological distress with FGIDs.

AREAS COVERED

This review critically evaluates whether anxiety and/or depression and FGIDs are causally related including evidence for a temporal sequence, strength and specificity of the association, biological gradient, and biological plausibility.

EXPERT OPINION

Accumulating evidence suggests that psychological factors are causal for symptoms in a subset of FGID patients and not explained by health care seeking behavior (brain-gut disorder). In other cases, psychological factors may arise secondary to intestinal disease (gut-brain disorder). Prospective population-based studies are needed in FGIDs other than IBS and FD to determine if a similar brain-gut and gut-brain syndrome exists. Treatment studies have not phenotyped FGIDs according to brain-gut versus gut-brain origins which may be important in understanding true treatment efficacy. Future research needs to unravel biological mechanisms that may explain the link between psychological factors and FGIDs but promising data in the area of the brain-gut-immune-microbe axis is emerging.

PPARγ: A turning point for irritable bowel syndrome treatment

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal (GI) disorder with negative impacts on quality of life of patients. Although the etiology of the disease is still unclear, there are a set of mechanisms and factors involved in IBS pathogenesis. Visceral hypersensitivity, impaired gut barrier, along with minor inflammation and oxidative stress are the most important triggers for IBS induction. Activation of peroxisome proliferator activated receptor-γ (PPAR-γ) has been shown to improve gut barrier, downregulate pro-inflammatory cytokines, reduce free radical production through antioxidative mechanisms, and exert anti-nociceptive effects against somatic pain. An electronic search in PubMed, Google Scholar, Scopus, and Cochrane library was performed and relevant clinical, in vivo and in vitro articles published between 2004 and June 2020 were collected. Search terms included "Irritable Bowel Syndrome" OR "IBS" OR "visceral hypersensitivity" OR "motility dysfunction" AND "peroxisome proliferator activated receptors" OR "PPAR". Herein, the efficacy of PPARγ signaling as a potential target for IBS treatment is reviewed.

Depression and anxiety associated with functional bowel disorders and its impact on quality of life: A cross-sectional study

BACKGROUND

Functional bowel disorder (FBD) is conceptualized as a "biopsychosocial disorder." Psychological factors are important moderators of symptom severity and persistence, treatment seeking and response to treatment. We investigated psychological factors and quality of life (QOL) in patients with FBD.

METHODS

Seventy patients visiting the department of medical gastroenterology diagnosed as FBD were included in the study. Severity of FBD was rated with FBD Severity Index. The Depression, Anxiety, and Stress Scale was applied and patients were divided into two groups, i.e., with moderate stress (Group A) and with severe stress (Group B). QOL in both the groups was assessed by WHOQOL-BREF Scale. Chi-square, t-test was done to compare the groups. Regression analysis was done to find predictors of poor QOL. P < 0.05 was taken as significant.

RESULTS

Patients of Group B had a longer duration of illness and had higher prevalence of depressive disorder (P = 0.03) in comparison to patients in Group A, who had higher prevalence of anxiety disorders (P = 0.06). Severity of FBD was positively correlated with depression (r = 0.8; P = 0.02). Physical and psychological QOL was significantly impaired in Group B patients having depression (P = 0.02; P = 0.03). Regression analysis showed a positive trend for presence of depressive disorder (P = 0.05), anxiety disorder (P = 0.08) and severity of FBD (P = 0.09) as predictors of poor QOL.

CONCLUSION

In our study, the high prevalence of stress, anxiety and depression in patients with FBD indicates the need for routine screening of such symptoms along with a collaborative and holistic treatment approach. Several etiological perspectives explaining the complex gut-brain interaction are also provided.

Contribution of ghrelin to functional gastrointestinal disorders’ pathogenesis

Functional gastrointestinal disorders (FGID) are heterogeneous disorders with a variety of clinical manifestations, primarily defined by signs and symptoms rather than a definite underlying cause. Their pathophysiology remains obscure and, although it is expected to differ according to the specific FGID, disruptions in the brain-gut axis are now thought to be a common denominator in their pathogenesis. The hormone ghrelin is an important component of this axis, exerting a wide repertoire of physiological actions, including regulation of gastrointestinal motility and protection of mucosal tissue. Ghrelin’s gene shows genetic polymorphism, while its protein product undergoes complex regulation and metabolism in the human body. Numerous studies have studied ghrelin’s relation to the emergence of FGIDs, its potential value as an index of disease severity and as a predictive marker for symptom relief during attempted treatment. Despite the mixed results currently available in scientific literature, the plethora of statistically significant findings shows that disruptions in ghrelin genetics and expression are plausibly related to FGID pathogenesis. The aim of this paper is to review current literature studying these associations, in an effort to uncover certain patterns of alterations in both genetics and expression, which could delineate its true contribution to FGID emergence, either as a causative agent or as a pathogenetic intermediate.

Irritable bowel syndrome - from etiopathogenesis to therapy

Irritable bowel syndrome (IBS) is a chronic and relapsing functional gastrointestinal disorder that affects 9-23% of the population across the world. Patients with IBS are often referred to gastroenterology, undergo various investigations, take various medicines, take time off work and have a poor quality of life. The pathophysiology of IBS is not yet completely understood and seems to be multifactorial. Many pathogenetic factors, in various combinations, and not all necessarily present in each patient, can play an important role. Discomfort or abdominal pain relieived by defacation, asociated with a change in stool form, is a typical clinical manifestation of IBS. Many factors, such as emotional stress and eating, may exacerbate the symptoms. A timely diagnosis of IBS is important so that treatment which will provide adequate symptomatic relief (diarrhoea, constipation, pain and boaring) can be introduced. The diagnosis of IBS is not confirmed by a specific test or structural abnormality. It is made using criteria based on clinical symptoms such as Rome criteria, unless the symptoms are thought to be atypical. Today the Rome Criteria IV is the current gold-standard for the diagnoses of IBS. Treatment of patients with IBS requires a multidisciplinary approach. Some patients respond well to non-pharmacological treatment, while others also require pharmacological treatment. This review will provide a summary of pathophysiology, diagnostic criteria and therapies for IBS.

Intrinsic brain abnormalities in irritable bowel syndrome and effect of anxiety and depression

This resting-state functional magnetic resonance imaging (rs-fMRI) study investigated intrinsic brain abnormalities in irritable bowel syndrome (IBS) and effect of anxiety and depression. Thirty IBS patients and 31 matched healthy controls underwent rs-fMRI scanning. Regional brain activity was evaluated by measuring the amplitude of low-frequency fluctuation (ALFF) and compared between IBS patients and healthy controls with a two-sample t-test. Areas with abnormal ALFF were further used as seeds in subsequent inter-regional functional connectivity (FC) analysis. Statistical analyses were also performed by including anxiety and depression as covariates to evaluate their effect. Compared to healthy controls, IBS patients showed decreased ALFF in several core default mode network regions (medial prefrontal cortex [MPFC], posterior cingulate cortex [PCC], bilateral inferior parietal cortices [IPC]), and in middle frontal cortex, right orbital part of the superior frontal gyrus (ORBsup), dorsal anterior cingulate cortex (dACC), and ventral anterior cingulated cortex (vACC), while they showed increased ALFF in bilateral posterior insula and cuneus. In addition, IBS patients revealed decreased inter-regional positive FC between MPFC and right ORBsup, between vACC and PCC, as well as decreased negative FC between MPFC and left posterior insula, while they showed increased negative FC between MPFC and cuneus. The inclusion of anxiety and depression as covariates abolished ALFF differences in dACC and vACC, but none of the FC differences.

IN CONCLUSION

IBS patients had disturbed intrinsic brain function. High levels of anxiety and depression in IBS patients could account for their decreased intrinsic brain activity in regions (the ACC) involved in affective processing.

Understanding the Gut Microbiota in Inflammatory and Functional Gastrointestinal Diseases

OBJECTIVE

During the last decade, experimental and observational studies have shown that patients with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) may have an altered intestinal microbial composition compared with healthy individuals. However, no uniform microbial signature has as yet been detected for either IBD or IBS. This review summarizes the current knowledge of microbial dysbiosis and its potential relationship to the pathophysiology in IBD and IBS.

METHODS

A selective review was conducted to summarize the current knowledge of gut microbiota in the pathophysiology of IBD and IBS.

RESULTS

Experimental and observational studies provide good evidence for intestinal microbial dysbiosis in subgroups of IBD and IBS. Still, no uniform disease pattern has been detected. This is most likely due to the heterogeneous nature of IBD and IBS, in combination with the effects of intrinsic and extrinsic factors. Such intrinsic factors include genetics, the gastrointestinal environment, and the host immune system, whereas extrinsic factors include early life diet, breastfeeding, and method of infant delivery.

CONCLUSIONS

Recent and ongoing work to define microbial dysbiosis in IBD and IBS shows promise, but future well-designed studies with well-characterized study individuals are needed. It is likely that the microbial dysbiosis in IBD and IBS is dependent on the natural disease course of IBD and symptom pattern in IBS. Therefore, assessment of the entire microbiota along the gastrointestinal tract, in relationship to confounding factors, symptom fluctuations, and other pathophysiological factors, is needed for further understanding of the etiology of these common diseases.

Effects of Cognitive Behavior Therapy on Heart Rate Variability in Young Females with Constipation-predominant Irritable Bowel Syndrome: A Parallel-group Trial

Background/Aims

The relation between heart rate variability (HRV) as non-invasive biomarkers of autonomic function and cognitive behavior therapy (CBT) as non-pharmacological treatments has rarely been examined in patients with constipation-predominant irritable bowel syndrome (IBS-C). The purpose of this study is to evaluate the efficacy of an 8-week CBT intervention on HRV and IBS symptoms, and the correlation of changes in HRV with changes in IBS symptoms among young female nursing students with IBS-C.

Methods

This study consisted of an exploratory subgroup analysis of 43 participants with IBS-C who had been randomly assigned to receive either 8 weeks of CBT (n = 23) or general medical information (control, n = 20). At baseline and 8, 16, and 24 weeks, participants completed a questionnaire assessing their gastrointestinal (GI) symptoms, anxiety, depression, and stress, and their HRV was measured via electrocardiography.

Results

At the 8-week follow-up, the high-frequency (HF) power was significantly higher, and the low-frequency (LF)/HF ratio was lower in the CBT group than in the control group (P < 0.001 for both), and the severity of GI symptoms (P = 0.003), anxiety (P < 0.001), depression (P < 0.001), and stress (P < 0.001) was significantly lower in the CBT group than in the control group. Changes in the HF power were significantly and inversely associated with changes in GI symptoms, anxiety, depression, and stress at 16 and 24 weeks (P < 0.05 for all; range of r from -0.37 to -0.68). Changes in the LF/HF ratio were also significantly and positively associated with changes in GI symptoms, anxiety, depression, and stress at 16 and 24 weeks (P < 0.05 for all; range of r from 0.38 to 0.60).

Conclusions

CBT was effective in managing symptoms in young IBS-C patients and the improvement of symptoms was sustained at 24 weeks following the completion of CBT. Furthermore, indirect measurement of autonomic function using HRV may be a useful objective parameter for assessing response to CBT in young IBS-C patients.

A Systematic Review of the Effects of Polyols on Gastrointestinal Health and Irritable Bowel Syndrome

Polyols are sugar alcohols found in certain fruits, vegetables, and sugar-free sweeteners. They make up a component of the diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which is gaining popularity in the treatment of patients with irritable bowel syndrome (IBS). We conducted a systematic review to evaluate the effects of polyols on the gastrointestinal tract in healthy men and women and in patients with IBS. Utilizing PubMed, Ovid, and Embase databases, we conducted a search on individual polyols and each of these terms: fermentation, absorption, motility, permeability, and gastrointestinal symptoms. Standard protocols for a systematic review were followed. We found a total of 1823 eligible articles, 79 of which were included in the review. Overall, available work has shown that polyol malabsorption generally occurs in a dose-dependent fashion in healthy individuals, and malabsorption increases when polyols are ingested in combination. However, studies in patients with IBS have shown conflicting results pertaining to polyol malabsorption. Polyol ingestion can lead to intestinal dysmotility in patients with IBS. Regarding the microbiome, moderate doses of polyols have been shown to shift the microbiome toward an increase in bifidobacteria in healthy individuals and may therefore be beneficial as prebiotics. However, data are limited regarding polyols and the microbiome in patients with IBS. Polyols can induce dose-dependent symptoms of flatulence, abdominal discomfort, and laxative effects when consumed by both healthy volunteers and patients with IBS. Further research is needed to better understand the effects of specific polyols on gastrointestinal function, sensation, and the microbiome in health and gastrointestinal disorders such as IBS.

Disturbed Interhemispheric Functional Connectivity Rather than Structural Connectivity in Irritable Bowel Syndrome

Neuroimaging studies have demonstrated that irritable bowel syndrome (IBS)-a relapsing functional bowel disorder-presents with disrupted brain connections. However, little is known about the alterations of interhemispheric functional connectivity and underlying structural connectivity in IBS. This study combined resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI) to investigate changes in interhemispheric coordination in IBS patients. Resting-state functional and structural magnetic resonance images were acquired from 65 IBS patients and 67 healthy controls (HCs; matched for age, sex and educational level). Interhemispheric voxel-mirrored homotopic connectivity (VMHC) was calculated and compared between groups. Homotopic regions showing abnormal VMHC in patients were targeted as regions of interest (ROIs) for analysis of DTI tractography. The fractional anisotropy (FA), fiber number and fiber length were compared between groups. Statistical analysis was also performed by including anxiety and depression as covariates to evaluate their effect. A Pearson correlation analysis between abnormal interhemispheric connectivity and clinical indices of IBS patients was performed. Compared to HCs, IBS patients had higher interhemispheric functional connectivity between bilateral thalami, cuneus, posterior cingulate cortices (PCC), lingual gyri and inferior occipital/cerebellum lobes, as well as lower interhemispheric functional connectivity between bilateral ventral anterior cingulate cortices (vACC) and inferior parietal lobules (IPL). The inclusion of anxiety and depression as covariates abolished VMHC difference in vACC. Microstructural features of white matter tracts connecting functionally abnormal regions did not reveal any differences between the groups. VMHC values in vACC negatively correlated with the quality of life (QOL) scores of patients. In conclusion, this study provides preliminary evidence of the disrupted functional coordination rather than anatomic coordination between interhemispheric regions within the cortex-thalamus circuit in IBS patients, which could partly account for the enhanced visceral information processing and impaired endogenous pain or emotion inhibition associated with IBS.

Diagnosis and treatment of diarrhea-predominant irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders worldwide. The economic impact of IBS on the health care system is substantial, as is the personal impact on patients. Patients with diarrhea-predominant IBS (IBS-D) comprise a substantial proportion of the overall IBS population. Primary care providers are often the first point of contact for patients with IBS-D and can accurately diagnose IBS after a careful history and examination without extensive diagnostic tests. Several pharmacologic treatments (eg, loperamide, alosetron, and antidepressants) and non-pharmacologic treatments (eg, dietary modification and probiotics) are available for IBS-D, but restrictions on use (eg, alosetron) or the lack of controlled trial data showing reductions in both global and individual IBS-D symptoms (eg, bloating, pain and stool frequency) emphasize the need for alternative treatment options. Two newer medications (eluxadoline and rifaximin) were approved in May 2015 for the treatment of IBS-D, and represent new treatment options for this common gastrointestinal condition.

Diagnosis and treatment of diarrhea-predominant irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders worldwide. The economic impact of IBS on the health care system is substantial, as is the personal impact on patients. Patients with diarrhea-predominant IBS (IBS-D) comprise a substantial proportion of the overall IBS population. Primary care providers are often the first point of contact for patients with IBS-D and can accurately diagnose IBS after a careful history and examination without extensive diagnostic tests. Several pharmacologic treatments (eg, loperamide, alosetron, and antidepressants) and non-pharmacologic treatments (eg, dietary modification and probiotics) are available for IBS-D, but restrictions on use (eg, alosetron) or the lack of controlled trial data showing reductions in both global and individual IBS-D symptoms (eg, bloating, pain and stool frequency) emphasize the need for alternative treatment options. Two newer medications (eluxadoline and rifaximin) were approved in May 2015 for the treatment of IBS-D, and represent new treatment options for this common gastrointestinal condition.

Inhibitory effects of SKI3246, the rhizome extract of Atractylodes japonica, on visceral hypersensitivity in experimental irritable bowel syndrome rat models

We evaluated the effect of SKI3246, the 50% ethanol extract of the rhizome of Atractylodes japonica, on visceral hypersensitivity, which is a major characteristic feature of IBS. We used various rat models of visceral hypersensitivity to assess the visceral pain responses to colorectal distension (CRD) in comparison with conventional IBS treatments. Oral administration of SKI3246 dose-dependently and significantly attenuated the abdominal withdrawal reflex (AWR) score in a model of acetic acid-induced visceral hypersensitivity. We also found that it reduced the number of abdominal contractions in response to CRD in a model of 2,4,6-trinitrobenzenesulfonic acid-induced visceral hypersensitivity, which was comparable to ramosetron or alosetron. Furthermore, treatment with SKI3246 also increased the pain threshold and abolished the elevated AWR scores to CRD in a rat model of neonatal maternal separation. We presumed that the modulation of the NK2 receptor is involved in the inhibitory activity of SKI3246 on the basis that it significantly inhibited the contraction of the distal colonic muscle induced by neurokinin A, the NK2 receptor agonist. The present results indicate that SKI3246 has the potential to be an effective therapeutic agent for IBS, especially insofar as it can relieve visceral hypersensitivity.

Cytokine imbalance in irritable bowel syndrome: a systematic review and meta-analysis

BACKGROUND

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder of unknown etiology; although infection and inflammation have recently been considered as important etiologic agents. A recent meta-analysis showed correlations between cytokine [interleukin-10 (IL-10) and tumor necrosis factor (TNF)] gene polymorphisms and IBS; however, it is still unknown whether patients with IBS have different cytokine profiles compared to healthy population.

METHODS

To determine the relationships between serum/plasma levels or mucosal expression of IL-10/TNF-α and IBS, we conducted a systematic review and meta-analysis based on case-control studies retrieved from PubMed and EMBASE search through August 2013. Standardized mean difference (SMD) was generated by using the inverse variance method. Heterogeneity was assessed based on I(2) values.

KEY RESULTS

Serum/plasma levels of TNF-α tended to be higher in IBS vs controls (p = 0.09); this reached significance in IBS subtypes vs controls and in female patients with IBS. However, serum/plasma levels of IL-10 were not significantly different in IBS patients vs controls. Further analysis of serum/plasma IL-10 levels in IBS subtypes did not show any difference; however, analysis based on gender showed a significantly lower serum/plasma IL-10 levels in male patients with IBS vs male controls (p = 0.02). Colonic IL-10 mRNA had a significantly lower expression in IBS vs control (p = 0.001).

CONCLUSIONS & INFERENCES

There is an imbalance of proinflammatory TNF-α, and anti-inflammatory IL-10, cytokines in IBS. Stratifying IBS patients based on cytokine profile may represent an opportunity for personalized treatment of this condition.

The relationship between irritable bowel syndrome and psychiatric disorders: from molecular changes to clinical manifestations

Irritable bowel syndrome (IBS) is a functional syndrome characterized by chronic abdominal pain accompanied by altered bowel habits. Although generally considered a functional disorder, there is now substantial evidence that IBS is associated with a poor quality of life and significant negative impact on work and social domains. Neuroimaging studies documented changes in the prefrontal cortex, ventro-lateral and posterior parietal cortex and thalami, and implicate alteration of brain circuits involved in attention, emotion and pain modulation. Emerging data reveals the interaction between psychiatric disorders including generalized anxiety disorder, panic disorder, major depressive disorder, bipolar disorder, and schizophrenia and IBS, which suggests that this association should not be ignored when developing strategies for screening and treatment. Psychological, social and genetic factors appear to be important in the development of IBS symptomatology through several mechanisms: alteration of HPA axis modulation, enhanced perception of visceral stimuli or psychological vulnerability. Elucidating the molecular mechanisms of IBS with or without psychiatric comorbidities is crucial for elucidating the pathophysiology and for the identification of new therapeutical targets in IBS.

Chronic functional bowel syndrome enhances gut-brain axis dysfunction, neuroinflammation, cognitive impairment, and vulnerability to dementia

The irritable bowel syndrome (IBS) is a common chronic functional gastrointestinal disorder world wide that lasts for decades. The human gut harbors a diverse population of microbial organisms which is symbiotic and important for well being. However, studies on conventional, germ-free, and obese animals have shown that alteration in normal commensal gut microbiota and an increase in pathogenic microbiota-termed "dysbiosis", impact gut function, homeostasis, and health. Diarrhea, constipation, visceral hypersensitivity, and abdominal pain arise in IBS from the gut-induced dysfunctional metabolic, immune, and neuro-immune communication. Dysbiosis in IBS is associated with gut inflammation. Gut-related inflammation is pivotal in promoting endotoxemia, systemic inflammation, and neuroinflammation. A significant proportion of IBS patients chronically consume alcohol, non-steroidal anti-inflammatories, and fatty diet; they may also suffer from co-morbid respiratory, neuromuscular, psychological, sleep, and neurological disorders. The above pathophysiological substrate is underpinned by dysbiosis, and dysfunctional bidirectional "Gut-Brain Axis" pathways. Pathogenic gut microbiota-related systemic inflammation (due to increased lipopolysaccharide and pro-inflammatory cytokines, and barrier dysfunction), may trigger neuroinflammation enhancing dysfunctional brain regions including hippocampus and cerebellum. These as well as dysfunctional vago-vagal gut-brain axis may promote cognitive impairment. Indeed, inflammation is characteristic of a broad spectrum of neurodegenerative diseases that manifest demntia. It is argued that an awareness of pathophysiological impact of IBS and implementation of appropriate therapeutic measures may prevent cognitive impairment and minimize vulnerability to dementia.

Emerging receptor target in the pharmacotherapy of irritable bowel syndrome with constipation

Preclinical experiments in rodent models have recently provided new information on the mechanisms underlying pain sensation in chronic visceral hypersensitivity, as well as insights into the mechanism of action of new drugs targeting abdominal pain in irritable bowel syndrome (IBS). This article describes the evidence base supporting the role of guanylate cyclase C (GC-C) activation in the modulation of gastrointestinal transit and, in particular, in visceral hypersensitivity. We propose that GC-C activation represents an important emerging target for pharmacotherapy in IBS with constipation (IBS-C), particularly given the recent regulatory approval of the GC-C agonist linaclotide as a treatment for IBS-C. More specifically, we address the following questions: "How is pain transmitted from the colon?"; "How is abdominal pain increased in IBS-C?"; "How can we reduce IBS-related abdominal pain - what drugs have been developed?"; "Does linaclotide reduce abdominal pain in animals and humans?"; and "How does linaclotide reduce abdominal pain?".

Management of irritable bowel syndrome with constipation: a flexible approach to treating a complex condition with multiple symptoms

Irritable bowel syndrome is a heterogeneous disease with a complex underlying pathophysiology and multiple symptoms - that is, clinical manifestation patterns. As such, management of irritable bowel syndrome requires a flexible approach tailored to the individual patient. This article reviews rational, evidence-based management strategy and treatment options for this variable condition.

A randomised controlled trial of a probiotic 'functional food' in the management of irritable bowel syndrome

Background

Irritable Bowel Syndrome (IBS) is a common condition characterised by pain, distension and altered bowel habit. Evidence suggests functional foods containing probiotics improve gastrointestinal transit, however, data are limited by short follow-up periods and evaluation in selected populations.

Methods

A multi-centre, randomized, double blind, controlled trial to evaluate the effect of a probiotic vs non-probiotic dairy product on symptoms in IBS with a constipation element (IBS – Constipation or IBS – Mixed profile). Set in 13 general practices within central England. Individuals meeting the ROME III criteria for IBS, aged 18–65 completed a pre-study diary. Eligible individuals were randomized to consume dairy ‘yoghurt’ products which either did or did not contain active probiotics twice daily and to complete a daily diary. Primary outcome was subjective global assessment of symptom relief at week 4. Other outcomes comprised, IBS symptom scores, pain, bloating and flatulence levels, stool frequency, stool consistency, ease of bowel movement and quality of life.

Results

179 were randomized (91 active, 88 placebo). 76 (43 active, 33 placebo) completed the study. No significant between group differences existed at 4 weeks (57% active vs 53% placebo, reported adequate relief (p = 0.71)). By week 8, 46% active vs 68% placebo reported adequate relief (p = 0.03). This was sustained at week 12.

Conclusions

Significant improvements were reported for most outcomes in all trial participants but improvement did not differ by group. This trial does not provide evidence for effectiveness of a probiotic in IBS, in variance with a body of published literature and review conclusions. Differential drop out may however cloud interpretation of data.

UK Trial registration:ISRCTN78863629

The gut microbiota and irritable bowel syndrome: friend or foe?

Progress in the understanding of the pathophysiology of irritable bowel syndrome (IBS), once thought to be a purely psychosomatic disease, has advanced considerably and low-grade inflammation and changes in the gut microbiota now feature as potentially important. The human gut harbours a huge microbial ecosystem, which is equipped to perform a variety of functions such as digestion of food, metabolism of drugs, detoxification of toxic compounds, production of essential vitamins, prevention of attachment of pathogenic bacteria to the gut wall, and maintenance of homeostasis in the gastrointestinal tract. A subset of patients with IBS may have a quantitative increase in bacteria in the small bowel (small intestinal bacterial overgrowth). Qualitative changes in gut microbiota have also been associated with IBS. Targeting the gut microbiota using probiotics and antibiotics has emerged as a potentially effective approach to the treatment of this, hitherto enigmatic, functional bowel disorder. The gut microbiota in health, quantitative and qualitative microbiota changes, and therapeutic manipulations targeting the microbiota in patients with IBS are reviewed in this paper.

High frequency of chronic bacterial and non-inflammatory prostatitis in infertile patients with prostatitis syndrome plus irritable bowel syndrome

BACKGROUND

Although prostatitis syndrome (PS) and irritable bowel syndrome (IBS) are common disorders, information on the prevalence of IBS in infertile patients with PS is relatively scanty. Therefore, this study was undertaken to estimate the frequency of PS and IBS and to evaluate the prevalence of the various diagnostic categories of prostatitis.

METHODOLOGY/PRINCIPAL FINDINGS

This study enrolled 152 patients with PS, diagnosed by the NIH-Chronic Prostatitis Symptom Index (NIH-CPSI) in an andrological setting, and 204 patients with IBS, diagnosed according to the Rome III diagnostic criteria in a gastroenterological setting. The patients with PS were asked to fulfill the Rome III questionnaire for IBS, whereas patients with IBS were asked to complete the NIH-CPSI. The simultaneous presence of PS and IBS was observed in 30.2% and 31.8% of the patients screened by andrologists and gastroenterologists, respectively. Altogether, 111 patients had PS plus IBS (31.2%). They had a total NIH-CPSI and pain subscale scores significantly higher than patients with PS alone. Gastrointestinal symptoms in patients with PS plus IBS were similar to those reported by patients with IBS alone and significantly greater in patients with PS alone. Patients with PS plus IBS had a significantly higher frequency of chronic bacterial prostatitis (category II) and lower of non-inflammatory prostatitis (category IIIB), compared to patients with PS alone. The frequency of inflammatory prostatitis (category IIIA) resulted similar.

CONCLUSIONS/SIGNIFICANCE

Prostatitis syndromes and IBS are frequently associated in patients with PS- or IBS-related symptoms. These patients have an increased prevalence of chronic bacterial and non-inflammatory prostatitis.

Functional changes induced by psychological stress are not enough to cause intestinal inflammation in Sprague-Dawley rats

BACKGROUND

It is well known that stress contributes to the perpetuation of several gastrointestinal diseases. However, its role as a trigger of the inflammatory process in absence of other putative contributing factors remains controversial. Our aim was to elucidate whether stress per se can induce a primary gut inflammation in non-predisposed rats.

METHODS

Male Sprague-Dawley rats were divided in sham and stress groups. Chronic stress was induced by subjecting animals 1 h day(-1) to wrap restraint or water avoidance stress alternatively for five consecutive days, as a model of ongoing life stress.

KEY RESULTS

Chronic stress induced a significant decrease in body weight gain without changes in food intake and an increase in frequency of defecation. Electromiografic (EMG) study showed that the duration of the migrating motor cycles (MMCs), but not its frequency, was shortened in stressed animals compared with non-stress conditions. Moreover, stressful stimulus caused mucosal mast cell hyperplasia and a decrease of iNOS mRNA expression. Bacterial translocation observed in stressed animals was not related to changes in epithelial barrier function and was not enough to induce intestinal inflammation.

CONCLUSIONS & INFERENCES

Decreased MMC duration, mast cell hyperplasia and decreased mRNA iNOS expression, but not altered epithelial barrier function, could be factors implicated in bacterial translocation-induced by chronic stress. However, these changes are not sufficient to induce intestinal inflammation in stress non-susceptible strain of rats.

Gastrointestinal-specific anxiety: an important factor for severity of GI symptoms and quality of life in IBS

BACKGROUND

Gastrointestinal (GI)-specific anxiety (GSA) has been proposed to influence symptom severity and quality of life (QOL) in patients with irritable bowel syndrome (IBS). The Visceral Sensitivity Index (VSI) is a recently developed, reliable and valid measure of GSA. Our aim was to evaluate the association between GSA, GI symptom severity, and QOL in IBS patients.

METHODS

Sixty healthy subjects and 306 patients fulfilling the Rome II criteria for IBS were studied. Demographic and disease-related factors were assessed. Patients completed VSI and GI Symptom Rating Scale (GSRS) and questionnaires to determine psychological symptom severity (Hospital Anxiety and Depression Scale), QOL (Short form 36), and presence of functional GI disorders (Rome II Modular Questionnaire).

KEY RESULTS

Compared with healthy subjects, patients with IBS had more severe GSA (34.7 +/- 16.9 vs. 2.2 +/- 4.4 [mean +/- standard deviation]; P < 0.0001). In the IBS group, more severe GSA was seen in patients with more severe GI symptoms (P < 0.0001), general anxiety (P < 0.0001) and depression (P < 0.0001), and with lower socioeconomic status (P < 0.05). In a regression analysis, GSA was the strongest predictor for GI symptom severity (GSRS total score), followed by number of Rome II diagnoses, presence of meal-related IBS symptoms, and gender (R(2) = 0.34). Gastrointestinal-specific anxiety was also, together with general anxiety, depression, socioeconomic status, and gender, found to be independently associated with mental QOL (R(2) = 0.62).

CONCLUSIONS & INFERENCES

Gastrointestinal-specific anxiety seems to be an important factor for GI symptom severity and QOL in patients with IBS.

Depression, anxiety and anger in subtypes of irritable bowel syndrome patients

The present study aimed to elucidate the differences in depression, anxiety, anger, and quality of life in a sample of non-psychiatric IBS patients, starting from the hypothesis that IBS subtypes may have different symptomatic expressions of negative emotions with different outcomes on quality of life measures. Forty-two constipation-predominant IBS (C-IBS) subjects and 44 diarrhea-predominant IBS (D-IBS) subjects, after an examination by a gastroenterologist and a total colonoscopy, underwent a clinical interview and psychometric examination for the assessment of depression, anxiety, anger and quality of life. IBS subtypes showed different symptomatic profiles in depression, anxiety and anger, with C-IBS patients more psychologically distressed than D-IBS subjects. Affective and emotional symptoms should be considered as specific and integral to the syndrome, and recognizing the differences between IBS subtypes may have relevant implications for treatment options and clinical outcome.

Current insights in to the pathophysiology of Irritable Bowel Syndrome

Irritable Bowel Syndrome (IBS) represents a functional disorder of gastrointestinal tract without the presence of an anatomic defect, in which abdominal pain is relieved with defecation and is associated with altered bowel habits.

IBS includes a wide range of symptoms while its pathophysiology is very complicated. Recent studies indicate that the most important mechanisms include visceral sensitivity, abnormal gut motility and autonomous nervous system dysfunction. The interactions between these three mechanisms make bowel's function susceptible to many exogenous and endogenous factors like gastrointestinal flora, feeding and psychosocial factors. Recent data indicate that according to the above mechanisms, the influence of genetic factors and polymorphisms of human DNA in the development of IBS is equally important.

Alosetron for severe diarrhea-predominant irritable bowel syndrome: safety and efficacy in perspective

Irritable bowel syndrome affects 5-10% of North Americans, with an estimated one-third having a diarrhea-predominant form. Alosetron hydrochloride (Lotronex) is a serotonin receptor type 3 antagonist approved in early 2000 for use in women with diarrhea-predominant irritable bowel syndrome (IBS-D). Initial use was widespread, but infrequent serious adverse events of ischemic colitis and severe constipation-related complications prompted alosetron's voluntary withdrawal from the US market in November 2000. Unprecedented public request prompted its reintroduction in 2002 under a Risk Management Plan, including a more restricted indication and a Prescribing Program for Lotronex. Despite these measures, the use of alosetron has been very limited since its reintroduction. Possible deterrents to its use include concerns over safety and the possible medical-legal implications raised by the Risk Management Plan. It is also possible that changes in the natural history and/or diagnosis of IBS-D have reduced the target population. Given the unique regulatory history of alosetron, these issues continue to engender controversy. This article profiles these concerns and reviews the pharmacology, clinical efficacy and safety, and post-marketing experience with alosetron. Myths and misconceptions related to alosetron use, or lack thereof, are addressed to provide the reader with the evidence needed to make informed treatment decisions for their female patients with severe IBS-D.

Altering the gastrointestinal flora in patients with functional bowel disorders: a way ahead?

Functional gastrointestinal disorders are very common in the Western world, but unfortunately the underlying mechanisms behind these disorders are incompletely understood. Treatment options are limited and the economic consequences for society are profound. Recent data suggest an involvement of bacteria in the pathogenesis of functional gastrointestinal disorders. Probiotics are promising new treatment alternatives, which will be reviewed in this supplement.

Influence of naloxone on rectal sensorimotor function in health

Abnormal rectal motor physiology and visceral hypersensitivity are implicated in the pathogenesis of irritable bowel syndrome. Endogenous opioids are involved in both the regulation of gut motility and the processing of sensory information. Our aim was to study the effect of suppression of endogenous opioid function by naloxone on rectal sensorimotor function in health. Eighteen healthy subjects participated in a rectal barostat study. Sensorimotor function was evaluated during two consecutive stepwise distensions separated by 30 min of basal tone recording, and with perception scoring on a 0-6 graded scale. Naloxone was administered, after 15 min of basal tone measurements, as an intravenous bolus (0.4 mg), followed by continuous infusion (20 microg kg(-1) h(-1)) in a placebo-controlled, single-blinded and randomized fashion. Naloxone did not alter rectal sensitivity. Comparison of visual analogue scale scores between naloxone and saline did not reveal altered intensities of pain or discomfort. Compared to the baseline distension, a significant adaptive increase in compliance occurred during the second distension after saline (7.8 +/- 0.7 vs 11.0 +/- 0.6 mL mmHg(-1), P = 0.0016). This dynamic change in rectal compliance did not occur after naloxone administration (8.8 +/- 0.7 vs 10.1 +/- 0.8 mL mmHg(-1), ns). Low intensity tonic distension induced a rectal adaptive relaxation, which was absent after naloxone. Naloxone does not alter rectal sensitivity but abolishes rectal adaptation in response to repeated balloon distention. These observations suggest that the endogenous opioid system is involved in control of rectal tone rather than rectal sensitivity.

Efficient diagnosis of suspected functional bowel disorders

Functional bowel disorders (FBDs) are common disorders that are characterized by various combinations of abdominal pain and/or discomfort, bloating and changes in bowel habits. At present, diagnosing FBDs often incurs considerable health-care costs, partly because unnecessary investigations are performed. Patients are currently diagnosed as having an FBD on the basis of a combination of typical symptoms, normal physical examination and the absence of alarm features indicative of an organic gastrointestinal disease. Basic laboratory investigations, such as a complete blood count, measurement of the erythrocyte sedimentation rate and serological tests for celiac disease, are useful in the initial evaluation. No further investigations are needed for most patients who have typical symptoms and no alarm symptoms. The most important alarm symptoms include signs of gastrointestinal bleeding, symptom onset above 50 years of age, a family history of colorectal cancer, documented weight loss and nocturnal symptoms. The presence of alarm symptoms obviously does not exclude an FBD, but further investigation is needed before confirmation of the diagnosis. For patients with predominant and severe diarrhea, a more thorough diagnostic work-up should normally be considered, including colonoscopy with colonic biopsies and a test for bile-acid malabsorption.

[Alterations of intestinal epithelial barrier and flora in the irritable bowel syndrome]

The irritable bowel syndrome (IBS) is a common bowel disorder that markedly impairs quality of life of patients. The causes of IBS symptoms are not well known. Motility and sensibility disorders, a genetic susceptibility, stress, previous GI infections and food intolerance have been involved in the pathogenesis of IBS. Recent investigations suggest that alterations of the intestinal epithelial barrier integrity, in particular increased permeability, could modify the cross-talk between bacterial microflora and the host, thus leading to persitent "low-grade" inflammation and alterated GI motility and sensitivity.

[Neurological and psychiatric aspects of some gastrointestinal diseases]

The gastrointestinal tract is controlled by the independent enteric nervous system. It is also closely connected to the central nervous system, and bi-directional communication exists between them. The communication involves neural pathways as well as immune and endocrine mechanisms. The brain-gut axis plays a prominent role in the modulation of gut functions. Signals from different sources (e.g. sound, sight, smell, somatic and visceral sensations, pain) reach the brain. These inputs are modified by memory, cognition and affective mechanisms and integrated within the neural circuits of the central nervous system, spinal cord, autonomic and enteral nervous systems. These inputs can have physiologic effects, such as changes in motility, secretion, immune function, and blood flow to the gastrointestinal tract. One of the most important neurotransmitters is serotonin that plays a key role in the pathogenesis of the most common chronic functional gastrointestinal disorder: the irritable bowel syndrome. It is a biopsychosocial disease, resulting from the dysregulation of the brain-gut axis. Endogenous pain facilitation rather than inhibition, pathologic gradation of visceral perception and reduced threshold for pain are all evident in these patients. Abuse history is common in their anamnesis. Exaggerated conscientiousness, perfectionism, oversensitivity, feeling of deficiency in effectiveness, and higher demand for social parity, neuroticism and alexithymia have been detected among their constant personality features. Females are also characterized by gender role conflict and low assertiveness. Antidepressants and psychotherapy have important roles in their treatment. Also patients with inflammatory bowel disease are characterized by neuroticism and alexithymia and altered mother-child attachment is often described in their anamnesis. Autonomic neuropathy is a frequent and early neurological complication. Reflux disease and obstructive sleep apnea mutually generate each other and their severities significantly correlate. In the celiac disease the most common neurological manifestations are ataxia, peripheral neuropathy and myopathy. Up to 85% of patients with histologically proven coeliac disease have no gastrointestinal symptoms; consequently, measurement of antigliadin antibody titre is therefore vital in all cases of idiopathic ataxia. Complete resolution of neurological symptoms is the result of gluten-free diet.

Gastric myoelectrical and motor abnormalities in children and adolescents with functional recurrent abdominal pain

BACKGROUND AND AIMS

Recurrent abdominal pain is common among children and adolescents. The majority of the affected patients have no apparent cause for their symptoms. This study evaluated gastric myoelectrical activity and motility abnormalities in children and adolescents with functional recurrent abdominal pain.

METHODS

Forty-two children with functional recurrent abdominal pain [19 (45.2%) males, mean 8 years, SD 3 years, 19 functional abdominal pain, 9 irritable bowel syndrome, 9 functional dyspepsia, 1 abdominal migraine, 1 aerophagia and 3 non-specific abdominal pain according to Rome III criteria] and 20 healthy children [10 (50%) males, mean 9 years, SD 2.7 years] from the same geographical area underwent electrogastrography (EGG), and ultrasonographic assessment of gastric emptying rate and antral motility.

RESULTS

Average gastric emptying rate, amplitude of antral contractions and antral motility index were lower in patients (46.5%, 74.3% and 6.5 respectively) compared to controls (66.17%, 89% and 8.3 respectively) (P < 0.001). Gastric emptying rate had a negative correlation with scores obtained for severity of symptoms (r = -0.63, P < 0.0001). Postprandial dominant frequency instability co-efficient (post-DFIC) was higher in patients than in controls (27.83% vs 18.3%, P = 0.0087), and correlated with the symptom score (r = 0.26, P = 0.045).

CONCLUSIONS

Gastric emptying and antral motility were significantly impaired in patients, indicating a possible role for gastric motility disturbances in the pathogenesis of childhood functional recurrent abdominal pain. Further studies, including therapeutic trials, are needed to confirm this association and for recommendation of prokinetic drugs in its management.

Altered rectal perception in irritable bowel syndrome is associated with symptom severity

BACKGROUND & AIMS

Diverging results exist regarding the connection between altered visceral perception and gastrointestinal (GI) symptoms, as well as the effects of psychological status on visceral sensitivity. We sought to investigate different aspects of rectal perception in irritable bowel syndrome (IBS) and the association with GI and psychological symptoms.

METHODS

We included 109 patients with IBS meeting Rome II criteria (77 women; age range, 20-71 years) and 29 healthy controls (21 women; age range, 20-68 years). They underwent rectal balloon distentions determining sensory thresholds for discomfort and pain, the perceived intensity of unpleasantness, and the viscerosomatic referral area. The fifth percentile (thresholds) and 95th percentile (unpleasantness and referral area) in controls were used to define altered perception. Questionnaires were used to assess severity of IBS-related GI symptoms and psychological symptoms.

RESULTS

When combining the 3 aspects of perception, 67 patients (61%) had altered rectal perception. These patients, compared with normosensitive patients, more frequently reported moderate or severe pain (73% vs 44%; P < .01), bloating (73% vs 36%; P < .0001), diarrhea (47% vs 21%; P < .01), satiety (39% vs 13%; P < .01), and clinically significant anxiety (31% vs 12%; P < .05). In a multivariate analysis, only pain and bloating remained associated with altered rectal perception.

CONCLUSIONS

Altered rectal perception is common in IBS and seems to be one important pathophysiologic factor associated with GI symptom severity in general and pain and bloating in particular. It is not just a reflection of the psychological state of the patient.

Inhibition of Phosphodiesterase Type 4 Decreases Stress-Induced Defecation in Rats and Mice

BACKGROUND/AIMS

Phosphodiesterase type 4 (PDE4) has been previously shown to regulate colonic contractile activity in vitro. In this study, the effects of PDE4 inhibition were assessed in a model of stress-induced defecation previously demonstrated to be due to increased colonic transit/evacuation.

METHODS

Rats were individually placed in a mild restraint cage and placed into a 12 degrees C environment (cold-restraint stress) for 60 min. Mice received restraint (only) stress at room temperature for 30 min. Loperamide (positive control compound) or two different PDE4 inhibitors (rolipram and roflumilast) were administered orally at several doses to the rodents 1 h before stress began. Vehicle alone was administered for comparison. The number of fecal pellets expelled during stress (fecal pellet output), total fecal pellet wet weight and total fecal water content were measured.

RESULTS

Loperamide produced a dose-related decrease (ID(50)s in mg/kg) in fecal pellet output (rat = 7.4, mouse = 0.7) and significantly decreased fecal wet weight (72.9%) and decreased fecal percent water content (9.4%). The two PDE4 inhibitors produced a similar dose-related inhibition of fecal pellet output. Rolipram exhibited ID(50)s in rat and mouse of 14.1 and 27.1, respectively. Rolipram significantly decreased fecal wet weight (58.8%) but increased fecal percent water content (15.0%). For roflumilast, ID(50)s were 24.2 mg/kg and 12.4 in the rat and mouse, respectively. Although roflumilast also significantly (p < 0.05) decreased fecal wet weight (47.2%), it did not significantly increase fecal percent water content.

CONCLUSIONS

These data indicate that PDE4 inhibition is effective in reducing rodent stress-induced defecation, provides the first functional data on a potential role for PDE4 activity in the colonic evacuation response to stress, and indicates the potential utility of PDE4 inhibitors in functional bowel disease such as irritable bowel syndrome requires further evaluation.

New insights into the pathogenesis and pathophysiology of irritable bowel syndrome

The pathogenesis and pathophysiology of irritable bowel syndrome is complex and still incompletely known. Potential pathogenetic factors include genes, infectious events, psychological symptoms and other loosely defined environmental factors. Both alterations at the central and peripheral level are thought to contribute to the symptoms of irritable bowel syndrome, including psychosocial factors, abnormal gastrointestinal motility and secretion, and visceral hypersensitivity. Today irritable bowel syndrome is viewed upon as a disorder of dysregulation of the so-called brain-gut axis, involving abnormal function in the enteric, autonomic and/or central nervous systems, with peripheral abnormalities probably dominating in some patients and disturbed central processing of signals from the periphery in others. Lines of evidence also suggest that inflammation within the gastrointestinal tract may be of great importance in at least subgroups of irritable bowel syndrome patients. To conclude, a complex picture of the pathogenesis and pathophysiology of irritable bowel syndrome is emerging, with interactions between several different alterations resulting in the divergent symptom pattern in these patients.

Spinal cord stimulation modulates intraspinal colorectal visceroreceptive transmission in rats

Previous studies have shown that spinal cord stimulation (SCS) of upper lumbar segments decreases visceromotor responses to mechanical stimuli in a sensitized rat colon and reduces symptoms of irritable bowel syndrome in patients. SCS applied to the upper cervical spinal dorsal column reduces pain of chronic refractory angina. Further, chemical stimulation of C1-C2 propriospinal neurons in rats modulates the responses of lumbosacral spinal neurons to colorectal distension. The present study was designed to compare the effects of upper cervical and lumbar SCS on activity of lumbosacral neurons receiving noxious colorectal input. Extracellular potentials of L6-S2 spinal neurons were recorded in pentobarbital anesthetized, paralyzed and ventilated male rats. SCS (50 Hz, 0.2 ms) at low intensity (90% of motor threshold) was applied to the dorsal column of upper cervical (C1-C2) or upper lumbar (L2-L3) ipsilateral spinal segments. Colorectal distension (CRD, 20 mmHg, 40 mmHg, 60 mmHg, 20s) was produced by air inflation of a latex balloon. Results showed that SCS applied to L2-L3 and C1-C2 segments significantly reduced the excitatory responses to noxious CRD from 417.6+/-68.0 to 296.3+/-53.6 imp (P<0.05, n=24) and from 336.2+/-64.5 to 225.0+/-73.3 imp (P<0.05, n=18), respectively. Effects of L2-L3 and C1-C2 SCS lasted 10.2+/-1.9 and 8.0+/-0.9 min after offset of CRD. Effects of SCS were observed on spinal neurons with either high or low-threshold excitatory responses to CRD. However, L2-L3 or C1-C2 SCS did not significantly affect inhibitory neuronal responses to CRD. C1-C2 SCS-induced effects were abolished by cutting the C7-C8 dorsal column but not by spinal transection at cervicomedullary junction. These data demonstrated that upper cervical or lumbar SCS modulated responses of lumbosacral spinal neurons to noxious mechanical stimulation of the colon, thereby, proved two loci for a potential therapeutic effect of SCS in patients with irritable bowel syndrome and other colonic disorders.