Exposure to severe wartime conditions in early life is associated with an increased risk of irritable bowel syndrome: a population-based cohort study

An Overview of the Influence of Breastfeeding on the Development of Inflammatory Bowel Disease

The first 1000 days of life is a critical period that contributes significantly to the programming of an individual's future health. Among the many changes that occur during this period early in life, there is growing evidence that the establishment of healthy gut microbiota plays an important role in the prevention of both short- and long-term health problems. Numerous publications suggest that the quality of the gut microbiota colonisation depends on several dietary factors, including breastfeeding. In this respect, a relationship between breastfeeding and the risk of inflammatory bowel disease (IBD) has been suggested. IBDs are chronic intestinal diseases, and perinatal factors may be partly responsible for their onset. We review the existence of links between breastfeeding and IBD based on experimental and clinical studies. Overall, despite encouraging experimental data in rodents, the association between breastfeeding and the development of IBD remains controversial in humans, partly due to the considerable heterogeneity between clinical studies. The duration of exclusive breastfeeding is probably decisive for its lasting effect on IBD. Thus, specific improvements in our knowledge could support dietary interventions targeting the gut microbiome, such as the early use of prebiotics, probiotics or postbiotics, in order to prevent the disease.

Elderberry diet improves gut-brain axis dysfunction, neuroinflammation, and cognitive impairment in the rat model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is related to a problem in the gut-brain axis. This experimental research aimed to shed light on the potential therapeutic application of elderberry (EB), which can work on the axis and get better the IBS symptoms. There were three groups (36 Sprague-Dawley rats) in this experiment, including control, IBS, and IBS with EB diet (IBS + EB). Making use of intracolonic instillation of 1 ml of 4% acetic acid for 30 s, IBS was induced. 7 days later, the EB extract (2%) was added to the diets of all animals for 8 weeks. Some histological, behavioral, and stereological techniques were used to detect the effects of EB on the gut and brain tissues. The findings showed that the EB diet improved locomotion and decreased anxiety-like behavior in the rat models of IBS. Moreover, the diet dropped the expression of TNF-α and increased mucosal layer thickness and the number of goblet and mast cells in colon tissue samples. In the hippocampal samples, administration of EB prevented astrogliosis and astrocyte reactivity. Although hippocampal and cortical neurons decreased markedly in the IBS group, EB prevented the drop in the number of neurons. Although lots of research is needed to elucidate the effectiveness of EB in IBS and its exact molecular mechanism, the result of this study showed that EB as an antioxidant and immune-modulatory agent could be a promising research target to prevent the impairment in the gut-brain axis, and could ameliorative classic IBS symptoms.

Role of inflammation in pediatric irritable bowel syndrome

BACKGROUND

IBS affects a large number of children throughout the world and is thought to be the result of disturbed neuroimmune function along with the brain-gut axis. Although the underlying pathophysiologic mechanisms are not clear, the role of low-grade inflammation and mucosal immune activation in IBS symptom generation has become evident also in subsets of pediatric patients. Animal models provided meaningful insight in the causal relationship between abnormal mucosal immune activation and changes in gastrointestinal (GI) sensory-motor function. Likewise, the development of long-standing GI symptoms fulfilling the current criteria for functional GI disorders after infection gastroenteritis and in patients with IBD or celiac disease in remission further supports this hypothesis. Immune activation, its impact on gut sensory-motor function, and potential implications for symptom generation emerged in both children and adults with IBS.

PURPOSE

The aim of this review is to summarize the main evidence on the presence of low-grade inflammation and immune activation in children with IBS, its possible role in symptom generation, and its potential implication for new therapeutic strategies.

Exposure to war and conflict: The individual and inherited epigenetic effects on health, with a focus on post-traumatic stress disorder

War and conflict are global phenomena, identified as stress-inducing triggers for epigenetic modifications. In this state-of-the-science narrative review based on systematic principles, we summarise existing data to explore the outcomes of these exposures especially in veterans and show that they may result in an increased likelihood of developing gastrointestinal, auditory, metabolic and circadian issues, as well as post-traumatic stress disorder (PTSD). We also note that, despite a potential "healthy soldier effect", both veterans and civilians with PTSD exhibit the altered DNA methylation status in hypothalamic-pituitary-adrenal (HPA) axis regulatory genes such as NR3C1. Genes associated with sleep (PAX8; LHX1) are seen to be differentially methylated in veterans. A limited number of studies also revealed hereditary effects of war exposure across groups: decreased cortisol levels and a heightened (sex-linked) mortality risk in offspring. Future large-scale studies further identifying the heritable risks of war, as well as any potential differences between military and civilian populations, would be valuable to inform future healthcare directives.

Understanding the Connection between Gut Homeostasis and Psychological Stress

Long-term exposure to adverse life events that provoke acute or chronic psychological stress (hereinafter "stress") can negatively affect physical health and even increase susceptibility to psychological illnesses, such as anxiety and depression. As a part of the hypothalamic-pituitary-adrenal axis, corticotropin-releasing factor (CRF) released from the hypothalamus is primarily responsible for the stress response. Typically, CRF disrupts the gastrointestinal system and leads to gut microbiota dysbiosis, thereby increasing risk of functional gastrointestinal diseases, such as irritable bowel syndrome. Furthermore, CRF increases oxidative damage to the colon and triggers immune responses involving mast cells, neutrophils, and monocytes. CRF even affects the differentiation of intestinal stem cells (ISCs), causing enterochromaffin cells to secrete excessive amounts of 5-hydroxytryptamine (5-HT). Therefore, stress is often accompanied by damage to the intestinal epithelial barrier function, followed by increased intestinal permeability and bacterial translocation. There are multi-network interactions between the gut microbiota and stress, and gut microbiota may relieve the effects of stress on the body. Dietary intake of probiotics can provide energy for ISCs through glycolysis, thereby alleviating the disruption to homeostasis caused by stress, and it significantly bolsters the intestinal barrier, alleviates intestinal inflammation, and maintains endocrine homeostasis. Gut microbiota also directly affect the synthesis of hormones and neurotransmitters, such as CRF, 5-HT, dopamine, and norepinephrine. Moreover, the Mediterranean diet enhances the stress resistance to some extent by regulating the intestinal flora. This article reviews recent research on how stress damages the gut and microbiota, how the gut microbiota can improve gut health by modulating injury due to stress, and how the diet relieves stress injury by interfering with intestinal microflora. This review gives insight into the potential role of the gut and its microbiota in relieving the effects of stress via the gut-brain axis.

Lessons learned from 25 Years of Research into Long term Consequences of Prenatal Exposure to the Dutch famine 1944-45: The Dutch famine Birth Cohort

This paper describes the findings of a historical cohort study of men and women born around the time of the Dutch famine 1944-45. It provided the first direct evidence in humans of the lasting consequences of prenatal undernutrition. The effects of undernutrition depended on its timing during gestation, and the organs and tissues undergoing periods of rapid development at that time. Early gestation appeared to be particularly critical, with the effects of undernutrition being most apparent, even without reductions in size at birth. Undernutrition during gestation affected the structure and function of organs and tissues, altered behaviour and increased risks of chronic degenerative diseases. This demonstrates the fundamental importance of maternal nutrition during gestation as the building blocks for future health.

Latest Insights on the Pathogenesis of Irritable Bowel Syndrome

The pathogenesis of irritable bowel syndrome is multifactorial and complex. Our understanding of its pathophysiology has evolved, but remains incompletely understood. Symptoms result from a dysregulation of brain-gut interactions. Evidence has identified alterations in central and peripheral (gut) mechanisms in irritable bowel syndrome and the bidirectional communication between the brain and the gut. Pertinent mechanisms include disturbed gut motility, visceral hypersensitivity, altered mucosal and immune function, altered gut microbiota, and altered central nervous system processing. This review addresses factors that increase the risk of irritable bowel syndrome and the central and peripheral mechanisms thought to underlie its symptoms.

Cohort profile: the Dutch famine birth cohort (DFBC)- a prospective birth cohort study in the Netherlands

PURPOSE

The Dutch famine birth cohort study was set up to investigate the effects of acute maternal undernutrition of the 1944-1945 Dutch famine during the specific stages of gestation on later health, with a particular focus on chronic cardiovascular and metabolic diseases, ageing and mental health.

PARTICIPANTS

The Dutch famine birth cohort consists of 2414 singletons born alive and at term in the Wilhelmina Gasthuis in Amsterdam around the time of the Dutch famine (1943-1947) whose birth records have been kept. The cohort has been traced and studied since 1994, when the first data collection started. The cohort has been interviewed and physically examined in several waves of data collection since that time, allowing repeated measures of a wide range of phenotypic information as well as the collection of biological samples (blood, urine, buccal swabs), functional testing (of heart, lungs, kidney, HPA axis) and imaging of the brain (MRI) and vasculature (ultrasound). Additionally, genetic and epigenetic information was collected. Through linkage with registries, mortality and morbidity information of the entire cohort has been obtained.

FINDINGS TO DATE

Prenatal famine exposure had lasting consequences for health in later life. The effects of famine depended on its timing during the gestation and the organs and tissues developing at that time, with most effects after exposure to famine in early gestation. The effects of famine were widespread and affected the structure and function of many organs and tissues, resulted in altered behaviour and increased risks of chronic degenerative diseases and increased mortality. The effects of famine were independent of size at birth, which suggests that programming may occur without altering size at birth.

FUTURE PLANS

As the cohort ages, we will be assessing the effects of prenatal undernutrition on (brain) ageing, cognitive decline and dementia, as well as overall morbidity and mortality.

REGISTRATION

The Dutch famine birth cohort is not linked to a clinical trial.

Mind and gut: Associations between mood and gastrointestinal distress in children exposed to adversity

Gastrointestinal and mental disorders are highly comorbid, and animal models have shown that both can be caused by early adversity (e.g., parental deprivation). Interactions between the brain and bacteria that live within the gastrointestinal system (the microbiome) underlie adversity-gastrointestinal-anxiety interactions, but these links have not been investigated during human development. In this study, we utilized data from a population of 344 youth (3-18 years old) who were raised with their biological parents or were exposed to early adverse caregiving experiences (i.e., institutional or foster care followed by international adoption) to explore adversity-gastrointestinal-anxiety associations. In Study 1, we demonstrated that previous adverse care experiences were associated with increased incidence of gastrointestinal symptoms in youth. Gastrointestinal symptoms were also associated with concurrent and future anxiety (measured across 5 years), and those gastrointestinal symptoms mediated the adversity-anxiety association at Time 1. In a subsample of children who provided both stool samples and functional magnetic resonance imaging of the brain (Study 2, which was a "proof-of-principle"), adversity was associated with changes in diversity (both alpha and beta) of microbial communities, and bacteria levels (adversity-associated and adversity-independent) were correlated with prefrontal cortex activation to emotional faces. Implications of these data for supporting youth mental health are discussed.

Global burden of irritable bowel syndrome: trends, predictions and risk factors

Irritable bowel syndrome (IBS) is one of the most common disorders of gut-brain interaction worldwide, defined according to patterns of gastrointestinal symptoms as described by the Rome diagnostic criteria. However, these criteria, developed with reference to research conducted largely in Western populations, might be limited in their applicability to other countries and cultures. Epidemiological data show a wide variation in the prevalence of IBS globally and more rigorous studies are needed to accurately determine any differences that might exist between countries as well as the potential explanations. The effects of IBS on the individual, in terms of their quality of life, and on health-care delivery and society, in terms of economic costs, are considerable. Although the magnitude of these effects seems to be comparable between nations, their precise nature can vary based on the existence of societal and cultural differences. The pathophysiology of IBS is complex and incompletely understood; genetics, diet and the gut microbiome are all recognized risk factors, but the part they play might be influenced by geography and culture, and hence their relative importance might vary between countries. This Review aims to provide an overview of the burden of IBS in a global context, to discuss future implications for the care of people with IBS worldwide, and to identify key areas for further research.

The role of the gut microbiome in opioid use

Although the gut and brain are separate organs, they communicate with each other via trillions of intestinal bacteria that collectively make up one's gut microbiome. Findings from both humans and animals support a critical role of gut microbes in regulating brain function, mood, and behavior. Gut bacteria influence neural circuits that are notably affected in addiction-related behaviors. These include circuits involved in stress, reward, and motivation, with substance use influencing gut microbial abnormalities, suggesting significant gut-brain interactions in drug addiction. Given the overwhelming rates of opioid overdose deaths driven by abuse and addiction, it is essential to characterize mechanisms mediating the abuse potential of opioids. We discuss in this review the role of gut microbiota in factors that influence opioid addiction, including incentive salience, reward, tolerance, withdrawal, stress, and compromised executive function. We present clinical and preclinical evidence supporting a bidirectional relationship between gut microbiota and opioid-related behaviors by highlighting the effects of opioid use on gut bacteria, and the effects of gut bacteria on behavioral responses to opioids. Further, we discuss possible mechanisms of this gut-brain communication influencing opioid use. By clarifying the relationship between the gut microbiome and opioid-related behaviors, we improve understanding on mechanisms mediating reward-, motivation-, and stress-related behaviors and disorders, which may contribute to the development of effective, targeted therapeutic interventions in opioid dependence and addiction.

The Therapeutic Effect of Exercise on Anxiety and Bowel Oxidative Stress in the Maternal Separation Animal Model

Introduction:

According to evidence, Early-Life Stress (ELS), mood disorders, and medical comorbidities, i.e. Irritable Bowel Syndrome (IBS), are correlated; however, the direct contribution of ELS to IBS manifestations is less understood. The current study aimed at evaluating the effect of voluntary exercise on the mitochondrial dysfunction of the bowel fibroblasts, following the confirmation of anxiety behavior.

Methods:

In this study, Postnatal Day (PND) rats underwent Maternal Separation (MS), as a valid animal model of the brain-gut axis dysfunction, in the days 2–14; three hours daily. On day 21, the study animals were divided into 4 groups, as follows: control, Running Wheel (RW) exercise, MS, and MS+RW groups. The study groups were housed in separate cages (4 rats per cage) until the onset of intervention. On day 60, the elevated plusmaze was used to assess anxiety-like behaviors; the level of oxidative stress biomarkers, i.e. Reactive Oxygen Species (ROS), Glutathione (GSH), as well as Adenosine Triphosphate (ATP) was measured to determine the gut mitochondrial function.

Results:

Findings revealed that ELS affected the gut energy metabolism in the studied rats; the negative effects of MS on anxiety and the gut mitochondrial dysfunction decreased via RW exercise during adolescence.

Conclusion:

Overall, anxiety behaviors and ROS production, leading to increased GSH and ATP levels, improved after RW exercise; this significantly impacts the function of colon secretory mitochondria. According to the positive effects of RW exercise on mitochondrial dysfunction in an ELS animal model, a potential relationship was found between the brain and gut in the study rats.

Animal Models for Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGID), such as functional dyspepsia (FD) and irritable bowel syndrome (IBS) are characterized by chronic abdominal symptoms in the absence of an organic, metabolic or systemic cause that readily explains these complaints. Their pathophysiology is still not fully elucidated and animal models have been of great value to improve the understanding of the complex biological mechanisms. Over the last decades, many animal models have been developed to further unravel FGID pathophysiology and test drug efficacy. In the first part of this review, we focus on stress-related models, starting with the different perinatal stress models, including the stress of the dam, followed by a discussion on neonatal stress such as the maternal separation model. We also describe the most commonly used stress models in adult animals which brought valuable insights on the brain-gut axis in stress-related disorders. In the second part, we focus more on models studying peripheral, i.e., gastrointestinal, mechanisms, either induced by an infection or another inflammatory trigger. In this section, we also introduce more recent models developed around food-related metabolic disorders or food hypersensitivity and allergy. Finally, we introduce models mimicking FGID as a secondary effect of medical interventions and spontaneous models sharing characteristics of GI and anxiety-related disorders. The latter are powerful models for brain-gut axis dysfunction and bring new insights about FGID and their comorbidities such as anxiety and depression.

Neurobehavioral dysfunction in non-alcoholic steatohepatitis is associated with hyperammonemia, gut dysbiosis, and metabolic and functional brain regional deficits

Non-alcoholic steatohepatitis (NASH) is one of the most prevalent diseases worldwide. While it has been suggested to cause nervous impairment, its neurophysiological basis remains unknown. Therefore, the aim of this study is to unravel the effects of NASH, through the interrelationship of liver, gut microbiota, and nervous system, on the brain and human behavior. To this end, 40 Sprague-Dawley rats were divided into a control group that received normal chow and a NASH group that received a high-fat, high-cholesterol diet. Our results show that 14 weeks of the high-fat, high-cholesterol diet induced clinical conditions such as NASH, including steatosis and increased levels of ammonia. Rats in the NASH group also demonstrated evidence of gut dysbiosis and decreased levels of short-chain fatty acids in the gut. This may explain the deficits in cognitive ability observed in the NASH group, including their depressive-like behavior and short-term memory impairment characterized in part by deficits in social recognition and prefrontal cortex-dependent spatial working memory. We also reported the impact of this NASH-like condition on metabolic and functional processes. Brain tissue demonstrated lower levels of metabolic brain activity in the prefrontal cortex, thalamus, hippocampus, amygdala, and mammillary bodies, accompanied by a decrease in dopamine levels in the prefrontal cortex and cerebellum and a decrease in noradrenalin in the striatum. In this article, we emphasize the important role of ammonia and gut-derived bacterial toxins in liver-gut-brain neurodegeneration and discuss the metabolic and functional brain regional deficits and behavioral impairments in NASH.

Irritable bowel syndrome – psychiatric issues

Introduction: Irritable bowel syndrome is a chronic gastrointestinal disease classified as a functional gastrointestinal disorder. It has been diagnosed on the basis of the so-called Rome IV criteria since 2016. The prevalence of IBS in the general population is about 10–20%, with most patients being women. The etiology of the syndrome is multifactorial and is associated with visceral sensory dysfunction, abnormalities of motor and secretory bowel function, a history of infectious diarrhea and abnormalities in gut microbiota, dysregulation of the brain–gut axis (the influence of the hypothalamic-pituitary-adrenal axis and sex hormones), genetic, psychosocial, and environmental factors, and the patient's personality traits. IBS patients may show differences in the structure and function of the brain when compared to healthy control individuals. Treatment of IBS involves the use of non-pharmacological interventions (psychotherapy, education, hypnotherapy, dietary modifications, regular physical activity) and pharmacotherapy (cholinolytic drugs, opioid receptor antagonists, tricyclic antidepressants, serotonin 5-HT3 receptor antagonists and 5-HT4 agonists).

Aim: The aim of the authors of this work is to draw attention to certain psychiatric aspects of the irritable bowel syndrome. It meets the criteria for a somatization disorder. Somatization is an important psychological factor directly related to the severity of IBS. It is estimated that the prevalence of psychiatric disorders among IBS patients ranges from 40% to 90% and is higher than in the general population. Affective disorders and anxiety disorders are the most commonly diagnosed.

Method: The article reviews the research and works available in the Google Scholar and PubMed databases combining the issue of IBS with psychiatric aspects, i.e. common for IBS and psychiatric disorders, etiopathogenesis, the concept of somatization in the context of IBS, and the coexistence of diseases and mental disorders with the irritable bowel syndrome.

Conclusion: Further research is needed to determine the causes of comorbidity of IBS and mental disorders.

Traumatic stress and the autonomic brain-gut connection in development: Polyvagal Theory as an integrative framework for psychosocial and gastrointestinal pathology

A range of psychiatric disorders such as anxiety, depression, and post-traumatic stress disorder frequently co-occur with functional gastrointestinal (GI) disorders. Risk of these pathologies is particularly high in those with a history of trauma, abuse, and chronic stress. These scientific findings and rising awareness within the healthcare profession give rise to a need for an integrative framework to understand the developmental mechanisms that give rise to these observations. In this paper, we introduce a plausible explanatory framework, based on the Polyvagal Theory (Porges, Psychophysiology, 32, 301-318, 1995; Porges, International Journal of Psychophysiology, 42, 123-146, 2001; Porges, Biological Psychology, 74, 116-143, 2007), which describes how evolution impacted the structure and function of the autonomic nervous system (ANS). The Polyvagal Theory provides organizing principles for understanding the development of adaptive diversity in homeostatic, threat-response, and psychosocial functions that contribute to pathology. Using these principles, we outline possible mechanisms that promote and maintain socioemotional and GI dysfunction and review their implications for therapeutic targets.

Pressure management as an occupational stress risk factor in irritable bowel syndrome: A cross-sectional study

Irritable Bowel Syndrome (IBS) is the most prevalent functional gastrointestinal disorder. Psychosocial stress is one of the pathogenic factors involved in the pathogenesis of IBS. The Pressure Management Indicator (PMI) is a validated questionnaire to analyze all aspects of occupational stress-a model involving sources of pressure, the mechanisms of coping, the personality, and the resulting effects of the interaction between these 3 elements. The purpose of this study was to analyze the association between socio-professional stress effects in IBS, and the relationship of IL-6 levels and salivary cortisol with occupational stress.We conducted a prospective cross-sectional study on 76 patients (39 patients with IBS, diagnosed according to the Rome III criteria and 37 healthy controls) who were investigated using a validated self-administered questionnaire: PMI. The biologic markers of chronic stress were analyzed using salivary cortisol and the immune response with serum interleukin 6 (IL-6).The IBS patients corresponded to the following subtypes: diarrhea-predominant: 22, constipation-predominant: 14 and mixed: 3. All the socio-professional pressure effects variables and scales were statistically significant, in an inversely proportional relation with IBS. Lower scores (poor effects) were found in IBS subjects. The adjusted odds ratios of having IBS versus healthy subjects for the socio-professional pressure effects scales were: 0.81 (95% confidence interval (CI) 0.72-0.88), for satisfaction, 0.85 (95% CI 0.78-0.91) for organization, 0.85 (95% CI 0.79-0.91) for mental wellbeing and 0.8 (95% CI 0.71-0.87) for physical wellbeing (P <.001). Also, the serum IL-6 levels were significantly higher in IBS than in controls (p < 0.001). There was no statistical difference between the salivary levels of cortisol between IBS patients and controls (P = .898).The level of occupational stress was higher in IBS patients compared to healthy subjects (socio-professional stress effects were lower in IBS patients) and correlated with IL-6 levels. Salivary cortisol was not associated with occupational pressure management.

Short-chain fatty acids: microbial metabolites that alleviate stress-induced brain-gut axis alterations

KEY POINTS

Chronic (psychosocial) stress changes gut microbiota composition, as well as inducing behavioural and physiological deficits. The microbial metabolites short-chain fatty acids (SCFAs) have been implicated in gastrointestinal functional, (neuro)immune regulation and host metabolism, but their role in stress-induced behavioural and physiological alterations is poorly understood. Administration of SCFAs to mice undergoing psychosocial stress alleviates enduring alterations in anhedonia and heightened stress-responsiveness, as well as stress-induced increases in intestinal permeability. In contrast, chronic stress-induced alterations in body weight gain, faecal SCFAs and the gene expression of the SCFA receptors FFAR2 and FFAR3 remained unaffected by SCFA supplementation. These results present novel insights into mechanisms underpinning the influence of the gut microbiota on brain homeostasis, behaviour and host metabolism, informing the development of microbiota-targeted therapies for stress-related disorders.

ABSTRACT

There is a growing recognition of the involvement of the gastrointestinal microbiota in the regulation of physiology and behaviour. Microbiota-derived metabolites play a central role in the communication between microbes and their host, with short-chain fatty acids (SCFAs) being perhaps the most studied. SCFAs are primarily derived from fermentation of dietary fibres and play a pivotal role in host gut, metabolic and immune function. All these factors have previously been demonstrated to be adversely affected by stress. Therefore, we sought to assess whether SCFA supplementation could counteract the enduring effects of chronic psychosocial stress. C57BL/6J male mice received oral supplementation of a mixture of the three principle SCFAs (acetate, propionate and butyrate). One week later, mice underwent 3 weeks of repeated psychosocial stress, followed by a comprehensive behavioural analysis. Finally, plasma corticosterone, faecal SCFAs and caecal microbiota composition were assessed. SCFA treatment alleviated psychosocial stress-induced alterations in reward-seeking behaviour, and increased responsiveness to an acute stressor and in vivo intestinal permeability. In addition, SCFAs exhibited behavioural test-specific antidepressant and anxiolytic effects, which were not present when mice had also undergone psychosocial stress. Stress-induced increases in body weight gain, faecal SCFAs and the colonic gene expression of the SCFA receptors free fatty acid receptors 2 and 3 remained unaffected by SCFA supplementation. Moreover, there were no collateral effects on caecal microbiota composition. Taken together, these data show that SCFA supplementation alleviates selective and enduring alterations induced by repeated psychosocial stress and these data may inform future research into microbiota-targeted therapies for stress-related disorders.

Allergic Proctocolitis Is a Risk Factor for Functional Gastrointestinal Disorders in Children

OBJECTIVE

To test the hypothesis that allergic proctocolitis, a cause of self-limiting rectal bleeding in infants, can predispose to the development of functional gastrointestinal disorders (FGIDs) later in childhood.

STUDY DESIGN

We studied a cohort of 80 consecutive patients diagnosed with allergic proctocolitis. Their sibling or matched children presenting to the same hospital for minor trauma served as controls. Parents of the patients with allergic proctocolitis and controls participated in a telephone interview every 12 months until the child was at least 4 years old. At that time, they were asked to complete the parental Questionnaire on Pediatric Gastrointestinal Symptoms, Rome III version.

RESULTS

Sixteen of the 160 subjects (10.0%) included in the study met the Rome III criteria for FGIDs. Among the 80 patients with allergic proctocolitis, 12 (15.0%) reported FGIDs, compared with 4 of 80 (5.0%) controls (P = .035). After adjustment for age and sex, the OR for FGIDs in allergic proctocolitis group was 4.39 (95% CI, 1.03-18.68). FGIDs were significantly associated with iron deficiency anemia, duration of hematochezia, and younger age at presentation. In a multivariate analysis, only the duration of hematochezia was significantly associated with the development of FGIDs (OR, 3.14; 95% CI,1.72-5.74).

CONCLUSIONS

We have identified allergic proctocolitis as a new risk factor for the development of FGIDs in children. Our data suggest that not only infection, but also a transient early-life allergic inflammatory trigger may induce persistent digestive symptoms, supporting the existence of "postinflammatory" FGIDs.

[Influence of cow's milk protein allergy on the diagnosis of functional gastrointestinal diseases based on the Rome IV standard in infants and young children]

OBJECTIVE

To study the influence of cow's milk protein allergy (CMPA) on the diagnosis of functional gastrointestinal diseases (FGID) based on the Rome IV standard in infants and young children.

METHODS

A total of 84 children aged 1 month to 3 years who were diagnosed with CMPA were enrolled as the case group, and 84 infants and young children who underwent physical examination and had no CMPA were enrolled as the control group. The pediatricians specializing in gastroenterology asked parents using a questionnaire for the diagnosis of FGID based on the Rome IV standard to assess clinical symptoms and to diagnose FGID.

RESULTS

The case group had a significantly higher incidence rate of a family history of allergies than the control group (P<0.05). In the case group, 38 (45%) met the Rome IV standard for the diagnosis of FGID, while in the control group, 13 (15%) met this standard (P<0.05). According to the Rome IV standard for FGID, the case group had significantly higher diagnostic rates of reflex, functional diarrhea, difficult defecation, and functional constipation than the control group (P<0.05). The children who were diagnosed with FIGD in the control group were given conventional treatment, and those in the case group were asked to avoid the intake of cow's milk protein in addition to the conventional treatment. After 3 months of treatment, the case group had a significantly higher response rate to the treatment than the control group (P<0.05).

CONCLUSIONS

In infants and young children, CMPA has great influence on the diagnosis of FGID based on the Rome IV standard. The possibility of CMPA should be considered during the diagnosis of FGID.

Maternal Separation Induced Visceral Hypersensitivity from Childhood to Adulthood

Background/Aims

Early adverse life events (EALs) are relevant to irritable bowel syndrome in adulthood. Maternal separation (MS), as one of the EALs, has proved to induce visceral hypersensitivity in adult rats. However, the effect of MS on visceral hypersensitvity from the post-weaning period to adulthood remains unknown.

Methods

One hundred and ten neonatal Sprague-Dawley rats were randomly divided into 2 groups: rats in the MS group were exposed to 3 hours daily MS on postnatal day (PND) 2–14; the normal control (NC) group remained undisturbed. Visceral sensitivity was determined by measuring the visceromotor response to colorectal distention on PND21, 35, and 56. Anxiety-like behaviors were measured by the open field test.

Results

Compared with NC rats, MS rats showed significant visceral hypersensitivity from the post-weaning period to adult. The proportion of visceral hypersensitive rats decreased with age from 87.5% to 70.0% in the female MS group and from 90.0% to 66.7% in the male MS group. The relative VMR ratio of MS and NC on PND21 was higher than PND35 and PND56. MS rats showed decreased ability of movement and exploration to the novel environment in the post-weaning period, obesity in the prepubertal period, and more anxiety-like behaviors in adulthood.

Conclusions

MS can significantly affect visceral sensitivity and behaviors of rats in different age stages, especially in the post-weaning period. Visceral hypersensitivity of MS rats is more pronounced in the post-weaning period and slightly restored in adults. Thus, visceral hypersensitivity in the post-weaning period might play a more meaningful pathophysiologic role in the formation of adult irritable bowel syndrome.

Oral treatment with Lactobacillus rhamnosus attenuates behavioural deficits and immune changes in chronic social stress

BACKGROUND

Stress-related disorders involve systemic alterations, including disruption of the intestinal microbial community. Given the putative connections between the microbiota, immunity, neural function, and behaviour, we investigated the potential for microbe-induced gut-to-brain signalling to modulate the impact of stress on host behaviour and immunoregulation.

METHODS

Male C57BL/6 mice treated orally over 28 days with either Lactobacillus rhamnosus (JB-1) ™ or vehicle were subjected to chronic social defeat and assessed for alterations in behaviour and immune cell phenotype. 16S rRNA sequencing and mass spectrometry were employed to analyse the faecal microbial community and metabolite profile.

RESULTS

Treatment with JB-1 decreased stress-induced anxiety-like behaviour and prevented deficits in social interaction with conspecifics. However, JB-1 did not alter development of aggressor avoidance following social defeat. Microbial treatment attenuated stress-related activation of dendritic cells while increasing IL-10+ regulatory T cells. Furthermore, JB-1 modulated the effect of stress on faecal metabolites with neuroactive and immunomodulatory properties. Exposure to social defeat altered faecal microbial community composition and reduced species richness and diversity, none of which was prevented by JB-1. Stress-related microbiota disruptions persisted in vehicle-treated mice for 3 weeks following stressor cessation.

CONCLUSIONS

These data demonstrate that despite the complexity of the gut microbiota, exposure to a single microbial strain can protect against certain stress-induced behaviours and systemic immune alterations without preventing dysbiosis. This work supports microbe-based interventions for stress-related disorders.

Depressive Symptoms and Coping Behaviors among Individuals with Irritable Bowel Syndrome in Japan

Objective Irritable bowel syndrome (IBS) is associated with a high prevalence of psychological disorders. Coping, which is used to manage stressful events, can have adaptive or maladaptive effects on a patient's health status. However, these coping behaviors have not been well studied in individuals with IBS. The association between the use of coping behaviors and the reported levels of depressive symptoms was examined in individuals with IBS. Methods Among 993 volunteers (382 men and 611 women) who participated in the Iwaki Health Promotion Project in 2013, we included 58 subjects who fulfilled the Rome III criteria for IBS in our analysis. Coping behaviors were assessed using the Brief Scale for Coping Profile (BSCP). The Center for Epidemiologic Studies Depression Scale (CES-D) was used to assess the four dimensions of depressive symptoms (depressed affect, somatic symptoms, interpersonal problems, and lack of positive affect) and the prevalence of probable depression using a cut-off score of 16. Results Among the 58 subjects with IBS, 22 (36.1%) exhibited probable depression. After adjustment for confounders, "active solution" was found to be significantly associated with somatic symptoms. Under the same conditions, "avoidance and suppression" was significantly associated with the CES-D total score, depressed affect, somatic symptoms, and (lack of) positive affect. There were no other significant relationships between depressive symptoms and the BSCP sub-scale scores. Conclusion These findings indicate that coping behaviors may influence the experience of depressive symptoms among individuals with IBS. Psychological therapy may reduce depressive symptoms as well as the severity of IBS symptoms. Additional studies are needed to examine the relationships between coping behaviors and depressive symptoms using a longitudinal study design.

Functional urological disorders: a sensitized defence response in the bladder-gut-brain axis

Functional urological and gastrointestinal disorders are interrelated and characterized by a chronic course and considerable treatment resistance. Urological disorders associated with a sizeable functional effect include overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). Poor treatment outcomes might be attributable to untreated underlying psychological and psychiatric disorders, as the co-occurrence of functional urological and gastrointestinal disorders with mood and anxiety disorders is common. The hypothetical bladder-gut-brain axis (BGBA) is a useful framework under which this interaction can be studied, suggesting that functional disorders represent a sensitized response to earlier threats such as childhood adversity or previous traumatic events, resulting in perceived emotional and bodily distress - the symptoms of functional disorders. Psychological and physical stress pathways might contribute to such alarm falsification, and neuroticism could be a risk factor for the co-occurrence of functional disorders and affective conditions. Additionally, physical threat - either from external sources or internal sources such as infection - might contribute to alarm falsification by influencing body-brain crosstalk on homeostasis and, therefore, affecting mood, cognition, and behaviour. Multidisciplinary research and an integrated care approach is, therefore, required to further elucidate and remediate functional urological and gastrointestinal polymorphic phenotypes.

Esophageal acid sensitivity and mucosal integrity in patients with functional heartburn

BACKGROUND

Patients with functional heartburn (FH) experience troublesome heartburn that is not related to gastroesophageal reflux. The etiology of the heartburn sensation in FH patients is unknown. In patients with reflux disease, esophageal hypersensitivity seems associated with impaired mucosal integrity. We aimed to determine esophageal sensitivity and mucosal integrity in FH and non-erosive reflux disease (NERD) patients.

METHODS

In this prospective experimental study, we performed an acid perfusion test and upper endoscopy with biopsies in 12 patients with NERD and nine patients with FH. Mucosal integrity was measured during endoscopy using electrical tissue impedance spectroscopy and biopsy specimens were analyzed in Ussing chambers for transepithelial electrical resistance and transepithelial permeability.

KEY RESULTS

Lag time to heartburn perception was significantly longer in FH patients (median 12 min) than in NERD patients (median 3 min). Once perceived, intensity of heartburn was scored equal with median visual analog scale 6.5 and 7.1 respectively. Esophageal mucosal integrity was also comparable between FH and NERD patients, both in vivo extracellular impedance and ex vivo transepithelial resistance and permeability were similar.

CONCLUSIONS & INFERENCES

Patients with FH did not show acid hypersensitivity as seen in patients with NERD. However, once perceived, intensity of heartburn is similar. Esophageal mucosal integrity is similar between NERD and FH patients, and is therefore unlikely to be the underlying cause of the observed difference in esophageal acid perception.

Irritable bowel syndrome and the perinatal period: lower birth weight increases the risk

BACKGROUND

Early life events have been found to be associated with irritable bowel syndrome (IBS) suggesting a role in development of functional disorders. The study aim was to identify potential perinatal risk factors for adult IBS.

METHODS

Utilizing a population-based nested case-control design, cases who met modified Rome III criteria for IBS and age- and-gender matched controls were identified using responses from prior mailed surveys to a random sample of Olmsted County residents. Medical records of eligible respondents were reviewed for perinatal events of interest. The association of early life events with subsequent case status was assessed using conditional logistic regression.

KEY RESULTS

Of 3 417 respondents, 513 were born in Olmsted County and 108 met criteria for IBS. Due to missing records, 89 pairs were included in the final analyses. Logistic regression revealed only birth weight as a predictor of IBS. Lower birth weight increased the odds for IBS (OR = 1.54 [95% CI = (1.12, 2.08), p = 0.008]). Median birth weight was 3.35 kg (range: 1.96-5.24) and 3.57 kg (range: 2.18-4.59) for cases and controls, respectively. Maternal age, delivery method, and antibiotic exposure were not associated with IBS status but this study was only powered to detect large odds ratios.

CONCLUSIONS AND INFERENCES

Lower birth weight was observed as a risk factor for IBS. It is not clear if in utero developmental delays directly lead to IBS or if low birth weight is a prospective marker for subsequent early life problems leading to IBS.

The Impact of Prenatal Exposure to Dexamethasone on Gastrointestinal Function in Rats

Antenatal treatment with synthetic glucocorticoids is commonly used in pregnant women at risk of preterm delivery to accelerate tissue maturation. Exposure to glucocorticoids during development has been hypothesized to underlie different functional gastrointestinal (GI) and motility disorders. Herein, we investigated the impact of in utero exposure to synthetic glucocorticoids (iuGC) on GI function of adult rats. Wistar male rats, born from pregnant dams treated with dexamethasone (DEX), were studied at different ages. Length, histologic analysis, proliferation and apoptosis assays, GI transit, permeability and serotonin (5-HT) content of GI tract were measured. iuGC treatment decreased small intestine size and decreased gut transit. However, iuGC had no impact on intestinal permeability. iuGC differentially impacts the structure and function of the GI tract, which leads to long-lasting alterations in the small intestine that may predispose subjects prone to disorders of the GI tract.

Childhood constipation as an emerging public health problem

Functional constipation (FC) is a significant health problem in children and contrary to common belief, has serious ramifications on the lives of children and their families. It is defined by the Rome criteria which encourage the use of multiple clinical features for diagnosis. FC in children has a high prevalence (0.7%-29%) worldwide, both in developed and developing countries. Biopsychosocial risk factors such as psychological stress, poor dietary habits, obesity and child maltreatment are commonly identified predisposing factors for FC. FC poses a significant healthcare burden on the already overstretched health budgets of many countries in terms of out-patient care, in-patient care, expenditure for investigations and prescriptions. Complications are common and range from minor psychological disturbances, to lower health-related quality of life. FC in children also has a significant impact on families. Many paediatric clinical trials have poor methodological quality, and drugs proved to be useful in adults, are not effective in relieving symptoms in children. A significant proportion of inadequately treated children have similar symptoms as adults. These factors show that constipation is an increasing public health problem across the world with a significant medical, social and economic impact. This article highlights the potential public health impact of FC and the possibility of overcoming this problem by concentrating on modifiable risk factors rather than expending resources on high cost investigations and therapeutic modalities.

The joint power of sex and stress to modulate brain-gut-microbiota axis and intestinal barrier homeostasis: implications for irritable bowel syndrome

BACKGROUND

Intestinal homeostasis is a dynamic process that takes place at the interface between the lumen and the mucosa of the gastrointestinal tract, where a constant scrutiny for antigens and toxins derived from food and microorganisms is carried out by the vast gut-associated immune system. Intestinal homeostasis is preserved by the ability of the mucus layer and the mucosal barrier to keep the passage of small-sized and antigenic molecules across the epithelium highly selective. When combined and preserved, immune surveillance and barrier's selective permeability, the host capacity of preventing the development of intestinal inflammation is optimized, and viceversa. In addition, the brain-gut-microbiome axis, a multidirectional communication system that integrates distant and local regulatory networks through neural, immunological, metabolic, and hormonal signaling pathways, also regulates intestinal function. Dysfunction of the brain-gut-microbiome axis may induce the loss of gut mucosal homeostasis, leading to uncontrolled permeation of toxins and immunogenic particles, increasing the risk of appearance of intestinal inflammation, mucosal damage, and gut disorders. Irritable bowel syndrome is prevalent stress-sensitive gastrointestinal disorder that shows a female predominance. Interestingly, the role of stress, sex and gonadal hormones in the regulation of intestinal mucosal and the brain-gut-microbiome axis functioning is being increasingly recognized.

PURPOSE

We aim to critically review the evidence linking sex, and stress to intestinal barrier and brain-gut-microbiome axis dysfunction and the implications for irritable bowel syndrome.

Structural & functional consequences of chronic psychosocial stress on the microbiome & host

INTRODUCTION

Given the lasting impact of psychological distress on behavior, along with the role of the microbiome in neurobehavioral development, we sought to examine the relationship between the microbiota and stress-induced behavioral deficits.

METHODS

Male C57BL/6 mice exposed to chronic social defeat were subjected to behavioral analysis and profiling of the intestinal microbiome. Mice were also analyzed for phenotypic and functional immune changes. A computational approach on 16S rRNA marker gene sequences was used to predict functional changes in the metagenome as a consequence of structural shifts in the microbiota.

RESULTS

Chronic social defeat induced behavioral changes that were associated with reduced richness and diversity of the gut microbial community, along with distinct shifts at the level of operational taxonomic units (OTU) across phyla. The degree of deficits in social, but not exploratory behavior was correlated with group differences between the microbial community profile. In silico analysis predicted a shift in the functional profile of the microbiome: defeated mice exhibited reduced functional diversity and a lower prevalence of pathways involved in the synthesis and metabolism of neurotransmitter precursors and short-chain fatty acids. Defeated mice also exhibited sustained alterations in dendritic cell activation, and transiently elevated levels of IL-10+ T regulatory cells that were suppressed over time.

CONCLUSIONS

This study indicates that stress-induced disruptions in neurologic function are associated with altered immunoregulatory responses and complex OTU-level shifts in the microbiota. It is thus suggested that a dysbiotic state, along with specific changes in microbial markers, may predict the onset of adverse neurocognitive deficits commonly observed following exposure to severe stressors. The data also predict novel pathways that might underlie microbiota-mediated effects on brain and behavior, thus presenting targets for investigations into mechanisms and potential therapy.

Role of environmental pollution in irritable bowel syndrome

Irritable bowel syndrome (IBS), with the prevalence of 10%-20 % of the population has become an emerging problem worldwide. IBS is a functional gastrointestinal (GI) disorder characterized by abdominal pain or discomfort and altered bowel habits. The etiology of IBS contains genetic, psychological, and immunological factors, and has not been fully elucidated; of note, recent studies also point at environmental pollution and its role in the development of functional GI diseases. In this review we focus on several environmental factors, such as bacterial contamination, air pollution, radiation and even stress as potential triggers of IBS. We discuss associated disturbances in homeostasis, such as changes in intestinal microbiome and related pathophysiological mechanisms. Based on the effect of environmental factors on the GI tract, we also propose novel targets in IBS treatment.

Early-life stress selectively affects gastrointestinal but not behavioral responses in a genetic model of brain-gut axis dysfunction

BACKGROUND

Early-life stress and a genetic predisposition to display an anxiety- and depressive-like phenotype are associated with behavioral and gastrointestinal (GI) dysfunction. Animals exposed to early-life stress, and those genetically predisposed to display anxiety or depressive behaviors, have proven useful tools in which to study stress-related GI disorders, such as irritable bowel syndrome (IBS). IBS is a heterogeneous disorder, and likely a consequence of both genetic and environmental factors. However, the combined effects of early-life stress and a genetic predisposition to display anxiety- and depression-like behaviors on GI function have not been investigated.

METHODS

We assessed the effect of maternal separation (MS) on behavioral and GI responses in WKY animals relative to a normo-anxious reference strain.

KEY RESULTS

Both non-separated (NS) WKY and WKY-MS animals displayed anxiety-like responses in the open-field test and depressive-like behaviors in the forced swim test relative to Sprague-Dawley rats. However, MS had no further influence on anxiety- and depressive-like behaviors exhibited by this stress-prone rat strain. Similarly, corticosterone levels measured after the OFT were insensitive to MS in WKY animals. However, WKY-MS displayed significantly increased colonic visceral hypersensitivity, fecal output, and altered colonic cholinergic sensitivity.

CONCLUSIONS & INFERENCES

Our data suggest that early-life stress, on the background of a genetic predisposition to display an anxiety- and depressive-like phenotype, selectively influences GI function rather than stress-related behaviors. Thus, our findings highlight the importance of genetic predisposition on the outcome of early-life adversity on GI function.

Prevalence and Predictive Factors of Irritable Bowel Syndrome in a Community-dwelling Population in Japan

OBJECTIVE

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder characterized by chronic, relapsing abdominal pain or discomfort and is associated with disturbed defecation. The pathogenesis of IBS is multifactorial. The aim of this study was to investigate the prevalence of IBS using the Rome III criteria and to assess the effects of mental and lifestyle factors on IBS in a community-dwelling population in Japan.

METHODS

The diagnosis of irritable bowel syndrome was based on the Japanese version of the Rome III Questionnaire. The questionnaire was administered to 993 volunteers who participated in the Iwaki Health Promotion Project 2013. Diet was assessed with a validated brief-type self-administered diet history questionnaire. Dietary patterns based on 52 predefined food groups [energy-adjusted food (g/d)] were extracted using a principal component analysis. The Center for Epidemiologic Studies Depression Scale with a cut-off point of 16 was used to assess the prevalence of depression.

RESULTS

A total of 61 subjects (6.1%) were classified as having IBS. Three dietary patterns were identified: "Healthy", "Western" and "Alcohol and accompanying" dietary patterns. After adjusting for potential confounders, the "Alcohol and accompanying" dietary pattern and depression were related to the risk of IBS.

CONCLUSION

We found that an "Alcohol and accompanying" dietary pattern and depression were related to the risk of IBS in a Japanese community population. However, we could not rule out the possibility of some selection bias. Further studies with longitudinal observations are therefore warranted.

Role of insular cortex in visceral hypersensitivity model in rats subjected to chronic stress

Abnormal processing of visceral sensation at the level of the central nervous system has been proven to be important in the pathophysiologic mechanisms of stress related functional gastrointestinal disorders. However, the specific mechanism is still not clear. The insular cortex (IC) was considered as one important visceral sensory area. Moreover, the IC has been shown to be involved in various neuropsychiatric diseases such as panic disorders and post-traumatic stress disorder. However, whether the IC is important in psychological stress related visceral hypersensitivity has not been studied yet. In our study, through destruction of the bilateral IC, we explored whether the IC played a critical role in the formation of visceral hypersensitivity induced by chronic stress on rats. Chronic partial restraint stress was used to establish viscerally hypersensitive rat model. Bilateral IC lesions were generated by N-methyl-D-day (door) aspartate. After a recovery period of 7 days, 14-day consecutive restraint stress was performed. The visceromotor response to colorectal distension was monitored by recording electromyogram to measure rats׳ visceral sensitivity. We found that bilateral insular cortex lesion could markedly inhibit the formation of visceral hypersensitivity induced by chronic stress. The insular cortex plays a critical role in the pathophysiology of stress-related visceral hypersensitivity.

Anxiety and depression comorbidities in irritable bowel syndrome (IBS): a systematic review and meta-analysis

Irritable bowel syndrome (IBS) has been associated with high prevalence of psychological disorders. However, it remains unclear whether IBS and each of its subtypes (predominant diarrhea IBS-D, constipation IBS-C, mixed IBS-M) are associated with higher anxiety and depressive symptoms levels. This study aimed to determine the associations of IBS and each of its subtypes with anxiety and/or depression. We conducted a systematic review and meta-analysis using five electronic databases (PubMed, PsychINFO, BIOSIS, Science Direct, and Cochrane CENTRAL). We selected case-control studies comparing anxiety and depression levels of patients with IBS to healthy controls, using standardized rating scales. Outcomes were measured as random pooled standardized mean differences (SMD). Ten studies were included in our analysis (885 patients and 1,384 healthy controls). Patients with IBS had significant higher anxiety and depression levels than controls (respectively, SMD = 0.76, 95 % CI 0.47; 0.69, p < 0.01, I2 = 81.7 % and SMD = 0.80, 95 % CI 0.42; 1.19, p < 0.01, I2 = 90.7 %). This significant difference was confirmed for patients with IBS-C and -D subtypes for anxiety, and only in IBS-D patients for depression. However, other IBS subtypes had a statistical trend to be associated with both anxiety and depressive symptomatology, which suggests a lack of power due to the small number of studies included. Patients with IBS had significantly higher levels of anxiety and depression than healthy controls. Anxiety and depression symptomatology should be systematically checked and treated in IBS patients, as psychological factors are important moderators of symptom severity, symptom persistence, decisions to seek treatment, and response to treatment.

Intestinal barrier function and the brain-gut axis

The luminal-mucosal interface of the intestinal tract is the first relevant location where microorganism-derived antigens and all other potentially immunogenic particles face the scrutiny of the powerful mammalian immune system. Upon regular functioning conditions, the intestinal barrier is able to effectively prevent most environmental and external antigens to interact openly with the numerous and versatile elements that compose the mucosal-associated immune system. This evolutionary super system is capable of processing an astonishing amount of antigens and non-immunogenic particles, approximately 100 tons in one individual lifetime, only considering food-derived components. Most important, to develop oral tolerance and proper active immune responses needed to prevent disease and inflammation, this giant immunogenic load has to be managed in a way that physiological inflammatory balance is constantly preserved. Adequate functioning of the intestinal barrier involves local and distant regulatory networks integrating the so-called brain-gut axis. Along this complex axis both brain and gut structures participate in the processing and execution of response signals to external and internal changes coming from the digestive tract, using multidirectional pathways to communicate. Dysfunction of brain-gut axis facilitates malfunctioning of the intestinal barrier, and vice versa, increasing the risk of uncontrolled immunological reactions that may trigger mucosal and brain low-grade inflammation, a putative first step to the initiation of more permanent gut disorders. In this chapter, we describe the structure, function and interactions of intestinal barrier, microbiota and brain-gut axis in both healthy and pathological conditions.

Visceral hypersensitivity and electromechanical dysfunction as therapeutic targets in pediatric functional dyspepsia

Functional gastrointestinal disorders (FGID) are common clinical syndromes diagnosed in the absence of biochemical, structural, or metabolic abnormalities. They account for significant morbidity and health care expenditures and are identifiable across variable age, geography, and culture. Etiology of abdominal pain associated FGIDs, including functional dyspepsia (FD), remains incompletely understood, but growing evidence implicates the importance of visceral hypersensitivity and electromechanical dysfunction. This manuscript explores data supporting the role of visceral hypersensitivity and electromechanical dysfunction in FD, with focus on pediatric data when available, and provides a summary of potential therapeutic targets.

Irritable bowel syndrome and symptom severity: evidence of negative attention bias, diminished vigour, and autonomic dysregulation

OBJECTIVE

To determine if cognitive processing, and subjective and physiological responses to stress and relaxation differed between an irritable bowel syndrome (IBS) group and control group. How these variables relate to the severity of IBS symptoms was also determined.

METHODS

Twenty-one IBS participants and 20 controls provided cognitive (attention and processing), subjective (perceived stress and vigour), and physiological (heart rate, blood pressure, and skin conductance) data during a relaxation and stress phase. Logistic regression analyses determined which variables are related to the IBS group and hierarchical linear regression assessed how the variables are related to the severity of IBS symptoms.

RESULTS

Subjective and cognitive factors (drowsiness at baseline, total vigour, and reduced Stroop colour-naming accuracy for negative words) are significantly related to IBS, χ2 (3, N=41)=23.67, p<.001, accurately categorising 85% of participants. IBS symptom severity was associated with both subjective (drowsiness at baseline and a smaller reduction in tiredness from relaxation to stress) and physiological (smaller increase in systolic blood pressure from baseline to stress phase and lower skin conductance at baseline) variables. This model predicted IBS severity, F (4, 16)=11.20, p<.001, and accounted for 74% of the variability in scores.

CONCLUSIONS

A negative attention bias, which may be related to a negative self-schema, as well as perceived low vigour were important in categorising IBS. Low subjective vigour and reduced physiological reactivity to both relaxation and stress conditions were associated with IBS severity, suggestive of illness-related allostatic load.

Chronic prenatal stress epigenetically modifies spinal cord BDNF expression to induce sex-specific visceral hypersensitivity in offspring

BACKGROUND

Irritable bowel syndrome (IBS) is a heterogeneous disorder with abdominal pain as one of the primary symptoms. The etiology of IBS remains unknown. Epidemiological studies found that a subset of these patients have a history of adverse early-life experiences. We tested the hypothesis that chronic prenatal stress (CPS) epigenetically enhances brain-derived neurotrophic factor (BDNF) in spinal cord to aggravate colon sensitivity to colorectal distension (CRD) differentially in male and female offspring.

METHODS

We used heterotypic intermittent chronic stress (HeICS) protocols in pregnant dams from E11 until delivery.

KEY RESULTS

Chronic prenatal stress induced significant visceral hypersensitivity (VHS) to CRD in male and female offspring. A second exposure to HeICS in adult offspring exacerbated VHS greater in female offspring that persisted longer than in male offspring. Chronic prenatal stress upregulated BDNF expression in the lumbar-sacral dorsal horn that correlated with the exacerbation of VHS in female, but not in male offspring. The upregulation of BDNF was due to a significant increase in RNA Pol II binding, histone H3 acetylation, and significant decrease in histone deacetylase 1 association with the core promoter of BDNF in female offspring. Other chronic prenatal and neonatal stress protocols were less effective than HeICS.

CONCLUSIONS & INFERENCES

The development of VHS, which contributes to the symptom of intermittent abdominal pain, is a two-step process, chronic in utero stress followed by chronic stress in adult-life. This two-step process induces aggravated and persistent colon hypersensitivity in female than in male offspring. Our preclinical model explains several clinical features in IBS patients.

Irritable bowel syndrome in middle-aged and elderly Palestinians: its prevalence and effect of location of residence

OBJECTIVES

The prevalence of irritable bowel syndrome (IBS) around the world is variable, ranging from as little as 1.1 to 45%. Limited studies have been carried out in Arab populations. The aim of this study was to determine the prevalence of IBS and its subtypes in the West Bank, Palestine, and to assess variation by locality of residence.

METHODS

We conducted a population-based, cross-sectional study. Participants were randomly selected from all districts of the West Bank, including cities, villages, and refugee camps, and they were at least 50 years of age. Participants completed the Rome III IBS questionnaire along with demographic data. The primary outcome was the effect of location of residence on the prevalence of IBS. A multivariable logistic regression model was used to assess the difference in IBS prevalence based on locality of residence.

RESULTS

A total of 1,601 people were approached for interview, of which 1,352 agreed to participate (response rate 84%). Most participants (53%; n=637) lived in urban centers. The overall prevalence of IBS was 30% (28-33%). IBS was more common in refugee camps (34%) and in villages (34%) compared with urban centers (27%) (P<0.05). Mixed IBS (IBS-M) was the most common of IBS subtypes (55%, n=244). In a multivariable logistic regression analysis, living in refugee camps (odds ratio (OR) 1.68 (95% confidence interval (CI) 1.14-2.40), P=0.005) and in villages (OR 1.33 (1.02-1.72), P=0.033) was associated with increased odds of having IBS when compared with residents of urban centers. IBS, IBS with constipation, and IBS-M were more common in women than in men (P<0.05).

CONCLUSIONS

The prevalence of IBS among middle-aged and elderly residents of Palestine is high. Residents in refugee camps and rural areas have a higher incidence of IBS than those in urban areas.

Susceptibility to stress-induced visceral sensitivity: a bad legacy for next generations

Despite high prevalence, the precise irritable bowel syndrome (IBS) pathophysiology remains poorly understood likely due to the heterogeneity of IBS populations and the multifactorial etiology of this disorder. Among risk factors, genetic predisposition and early life trauma have been reported. In this context, the debate on genetic or environmental influences in the IBS pathogenesis is still open. The study by van der Wijngaard et al., reporting for the first time that susceptibility to stress-induced visceral hypersensitivity in maternally separated rats can be transferred to the next generation without any further exposure of F2 individuals to maternal separation, supports the importance of environmental influence in the IBS phenotype. Epigenetic mechanisms such as hypermethylation in the promoter region of the glucocorticoid receptor gene mediating the long-term and transgenerational behavioral effects of maternal care on the development have been shown in some but not in all studies. Van der Wijngaard et al. incriminated maternal care in the transmitted susceptibility to stress-induced visceral hypersensitivity, but not changes in glucocorticoid receptor protein expression in the brain. This finding opens a broad field of future directions aimed at evaluating the mechanisms involved in the transmission across generations of the digestive features of IBS, including, for example, on the role of gut microbiota changes in vertical transmission or epigenetic modifications of intestinal mast cells and the junctional region of intestinal epithelial cells in vertical transfer.

Developmental origins of colon smooth muscle dysfunction in IBS-like rats

Epidemiological studies show that subsets of adult and pediatric patients with irritable bowel syndrome (IBS) have prior exposures to psychological or inflammatory stress. We investigated the cellular mechanisms of colonic smooth muscle dysfunction in adult rats subjected to neonatal inflammation. Ten-day-old male rat pups received 2,4,6-trinitrobenzene sulfonic acid to induce colonic inflammation. Colonic circular smooth muscle strips were obtained 6 to 8 wk later. We found that about half of the neonate pups subjected to inflammatory insult showed a significant increase in expression of the pore-forming α1C-subunit of Cav1.2b channels in adult life. These were the same rats in whom Vip mRNA increased in the colon muscularis externae. Additional experiments showed reduced interaction of histone deacetylase (HDAC) 3 with α1C1b promoter that increased the acetylation of histone H3 lysine 9 (H3K9) in the core promoter region. Vasoactive intestinal peptide (VIP) treatment of naïve muscularis externae swiftly recruited CREB-binding protein (CBP) to the α1C1b promoter and dissociated HDAC3 from this region to initiate transcription. The CBP interaction with the α1C1b promoter was transient, but the dissociation of HDAC3 persisted to sustain H3K9 hyperacetylation and increase in transcription. Intraperitoneal treatment of adult naïve rats with butyrate mimicked the effects of neonatal colon inflammation. We concluded that neonatal inflammation upregulates VIP in the colon muscularis externae, which modulates epigenetic events at the α1C1b promoter to activate α1C1b gene transcription. Inflammatory insult in early life may be one of the etiologies of smooth muscle dysfunction in adult life, which contributes to the altered motility function in patients with diarrhea-predominant IBS.

Umbilical hernia repair increases the rate of functional gastrointestinal disorders in children

OBJECTIVES

To hypothesize that hernia repair would not change the incidence of functional gastrointestinal disorders (FGIDs) due to the benign and limited nature of the procedure.

STUDY DESIGN

This cohort study assessed a randomized selection of children aged 4-18 years who underwent hernia repair more than 4 years prior at Ann and Robert H. Lurie Children's Hospital of Chicago. Controls were siblings who had not undergone surgery previously. Parents completed the Questionnaire on Pediatric Gastrointestinal Symptoms-Rome III Version by telephone for subjects and controls. The primary outcome was the presence of FGIDs.

RESULTS

Fifty children with hernia repair and 43 sibling controls were identified. At the time of survey, subjects with hernia repair were average age 12.9 years (range 5-18 years, 60% male) and controls were average age 12.2 years (range 4-18 years, 49% male). Average age at surgical repair was 5.2 years (median 5.2 years, range 0.2-10.4 years) and average time since surgical repair was 7.8 years (range 4.8-13.7 years). FGIDs were diagnosed in 10/50 (20%) cases of hernia repair and 2/43 (5%) controls (P = .033, Fisher 2-tailed test).

CONCLUSIONS

Umbilical hernia repair increases the likelihood of FGIDs in childhood. Additional studies are needed to identify aspects of surgery that may be associated with development of FGIDs.

Stress-induced visceral hypersensitivity in maternally separated rats can be reversed by peripherally restricted histamine-1-receptor antagonists

Background

The histamine-1 receptor (H1R) antagonist ketotifen increased the threshold of discomfort in hypersensitive IBS patients. The use of peripherally restricted and more selective H1R antagonists may further improve treatment possibilities. We examined the use of fexofenadine and ebastine to reverse post-stress visceral hypersensitivity in maternally separated rats.

Methods

The visceromotor response to colonic distension was assessed in adult maternally separated and nonhandled rats pre- and 24 hours post water avoidance. Subsequently rats were treated with vehicle alone or different dosages of fexofenadine (1.8 and 18 mg/kg) or ebastine (0.1 and 1.0 mg/kg) and re-evaluated. Colonic tissue was collected to assess relative RMCP-2 and occludin expression levels by Western blot and histamine-1 receptor by RT-qPCR. β-hexosaminidase release by RBL-2H3 cells was used to establish possible mast cell stabilizing properties of the antagonists.

Key results

Water avoidance only induced enhanced response to distension in maternally separated rats. This response was reversed by 1.8 and 18 mg/kg fexofenadine. Reversal was also obtained by 1.0 but not 0.1 mg/kg ebastine. RMCP-2 expression levels were comparable in these two ebastine treatment groups but occludin was significantly higher in 1.0 mg/kg treated rats. There were no differences in histamine-1 receptor expression between nonhandled and maternally separated rats. Fexofenadine but not ebastine showed mast cell stabilizing quality.

Conclusions

Our results indicate that the peripherally restricted 2^nd generation H1-receptor antagonists fexofenadine and ebastine are capable of reversing post stress visceral hypersensitivity in rat. These data justify future IBS patient trials with these well tolerated compounds.

Which psychological factors exacerbate irritable bowel syndrome? Development of a comprehensive model

OBJECTIVE

There is evidence that psychological factors affect the onset, severity and duration of irritable bowel syndrome (IBS). However, it is not clear which psychological factors are the most important and how they interact. The aims of the current study are to identify the most important psychological factors predicting IBS symptom severity and to investigate how these psychological variables are related to each other.

METHODS

Study participants were 286 IBS patients who completed a battery of psychological questionnaires including neuroticism, abuse history, life events, anxiety, somatization and catastrophizing. IBS severity measured by the IBS Severity Scale was the dependent variable. Path analysis was performed to determine the associations among the psychological variables, and IBS severity.

RESULTS

Although the hypothesized model showed adequate fit, post hoc model modifications were performed to increase prediction. The final model was significant (Chi(2)=2.2; p=0.82; RMSEA<.05) predicting 36% of variance in IBS severity. Catastrophizing (standardized coefficient (β)=0.33; p<.001) and somatization (β=0.20; p<.001) were the only two psychological variables directly associated with IBS severity. Anxiety had an indirect effect on IBS symptoms through catastrophizing (β=0.80; p<.001); as well as somatization (β=0.37; p<.001). Anxiety, in turn, was predicted by neuroticism (β=0.66; p<.001) and stressful life events (β=0.31; p<.001).

CONCLUSION

While cause-and-effect cannot be determined from these cross-sectional data, the outcomes suggest that the most fruitful approach to curb negative effects of psychological factors on IBS is to reduce catastrophizing and somatization.

Early life events predispose the onset of childhood functional gastrointestinal disorders

BACKGROUND

Functional gastrointestinal disorders (FGIDs) are common digestive conditions characterized by chronic or recurrent symptoms in the absence of a clearly recognized gastrointestinal etiology. The biopsychosocial model, the most accepted concept explaining chronic pain conditions, proposes that the interplay of multiple factors such as genetic susceptibility, early life experiences, sociocultural issues, and coping mechanisms affect children at different stages of their lives leading to the development of different pain phenotypes and pain behaviors. Early life events including gastrointestinal inflammation, trauma, and stress may result in maladaptive responses that could lead to the development of chronic pain conditions such as FGIDs.

AIMS

In this review, we discuss novel findings from studies regarding the long-term effect of early life events and their relationship with childhood chronic abdominal pain and FGIDs.

METHODS

A bibliographic search of the PubMed database was conducted for articles published over the last 20 years using the keywords: "Functional gastrointestinal disorders", "chronic abdominal pain", "chronic pain", "gastrointestinal inflammation", and "early life events". Forty-three articles were chosen for review.

RESULTS

Based on the current evidence, events that take place early in life predispose children to the development of chronic abdominal pain and FGIDs. Conditions that have been studied include cow's milk protein hypersensitivity, pyloric stenosis, gastrointestinal infections, and Henoch-Schonlein purpura, among others.

CONCLUSIONS

Early events may play an important role in the complex pathogenesis of functional gastrointestinal conditions. Timely intervention may have a critical impact on the prevention of this group of chronic incapacitating conditions.

Why dyspepsia can occur without organic disease: pathogenesis and management of functional dyspepsia

Functional dyspepsia (FD), one of the most common conditions in medicine, is a gastrointestinal disorder in which the patient suffers from chronic dyspeptic symptoms such as epigastralgia and a heavy feeling in the stomach despite the absence of organic disease. Elucidating the pathogenesis of FD means answering the question, "Why do symptoms occur?" The factors contributing to symptom manifestation in FD probably should be divided into 3 categories: (1) physiological abnormalities that directly induce symptoms, (2) factors that modify those physiological abnormalities, and (3) factors that govern abnormal responses to stress. The symptoms of FD are directly caused by two major physiological abnormalities-abnormal gastric motility and visceral hypersensitivity-occurring in patients who have acquired excessive responsiveness to stress as a result of the environment during early life, genetic abnormalities, residual inflammation after gastrointestinal infections, or other causes, with the process modified by factors including psychophysiological abnormalities, abnormal secretion of gastric acid, Helicobacter pylori infection, diet, and lifestyle. If the basis of this model of FD pathogenesis is excessive responsiveness of gastrointestinal function to stress and external stimuli, psychosomatic approaches to alter stress perception could be important treatment options. However, in the primary care setting, the treatment of FD has focused on local gastric factors, including abnormal gastric acid secretion, abnormal gastric motility, and H. pylori infection. Acid secretion inhibitors and prokinetics have been commonly used, and H. pylori eradication therapy has been carried out, but the effectiveness of drug therapy has been limited.

Mucosal immune cell numbers and visceral sensitivity in patients with irritable bowel syndrome: is there any relationship?

OBJECTIVES

Repeated exposure to stress leads to mast cell degranulation, microscopic inflammation, and subsequent visceral hypersensitivity in animal models. To what extent this pathophysiological pathway has a role in patients with the irritable bowel syndrome (IBS) has not been properly investigated. The objective of this study was to assess the relationship between visceral hypersensitivity, microscopic inflammation, and the stress response in IBS.

METHODS

Microscopic inflammation of the colonic mucosa was evaluated by immunohistochemistry in 66 IBS patients and 20 healthy volunteers (HV). Rectal sensitivity was assessed by a barostat study using an intermittent pressure-controlled distension protocol. Salivary cortisol to a psychological stress was measured to assess the stress response.

RESULTS

Compared with HV, mast cells, T cells, and macrophages were decreased in IBS patients. Similarly, λ-free light chain (FLC)-positive mast cells were decreased but not immunoglobulin E (IgE)- and IgG-positive mast cells. There were no differences between hypersensitive and normosensitive IBS patients. No relation was found between any of the immune cells studied and the thresholds of discomfort, urge, first sensation, or IBS symptoms (e.g., abdominal pain, stool-related complaints, bloating). Finally, stress-related symptoms and the hypothalamic-pituitary-adrenal-axis response to stress were not correlated with the number of mast cells or the presence of visceral hypersensitivity.

CONCLUSIONS

Although the number of mast cells, macrophages, T cells, and λFLC-positive mast cells is decreased in IBS compared with HV, this is not associated with the presence of visceral hypersensitivity or abnormal stress response. Our data question the role of microscopic inflammation as an underlying mechanism of visceral hypersensitivity, but rather suggest dysregulation of the mucosal immune system in IBS.