Genetic epidemiology of irritable bowel syndrome

The Role of Diet in the Management of Irritable Bowel Syndrome: A Comprehensive Review

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder that has a significant impact on the general population. The suboptimal medical treatments available for IBS contribute to its large economic burden. The pathophysiology of IBS is complex, and treatments often focus on managing specific symptoms. Many individuals with IBS associate their symptoms with specific food intake, leading to increased scientific research on the role of diet in managing IBS. Dietary management has become a crucial aspect of IBS treatment, with initial recommendations focusing on adopting a healthy eating pattern and lifestyle. This comprehensive review aims to synthesise the current literature on the impact of diet on IBS, exploring various dietary approaches to managing IBS, including the low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet, gluten-free diet, Mediterranean diet, and tritordeum-based diet. It presents evidence from both experimental and observational studies and summarises the underlying dietary triggers in IBS, including gut microbiota dysbiosis, visceral hypersensitivity, and immune activation. In addition, it explores the efficacy and limitations of the key diet and lifestyle recommendations provided by dietary guidelines and scientific literature, highlighting the importance of individualised dietary strategies tailored to the unique needs of different types of IBS patients. By elucidating the complex interplay between diet and IBS pathophysiology, this review provides valuable insights into optimising dietary management approaches for improving symptom control and enhancing the quality of life for individuals with IBS.

Evaluation of the Impact of Some Single-Nucleotide Gene Polymorphisms on the Development of Adenomatous Polyps of the Colon in Patients with Irritable Bowel Syndrome

BACKGROUND

The number of cases of irritable bowel syndrome is growing worldwide, in which adenomatous polyps can develop as a result of microinflammation of the colonic epithelium. Our study was aimed at the identification of the possible effect of single-nucleotide polymorphisms on the risk of the development of irritable bowel syndrome-related colonic adenomatous polyps.

MATERIALS AND METHODS

The study involved 187 irritable bowel syndrome patients. The single-nucleotide polymorphisms were investigated by the polymerase chain reaction method and DNA was extracted with the phenol-chloroform: interleukin-1β gene-31C/T (rs1143627), -511C/T (rs16944); interleukin-6 gene-174G/C (rs1800795); interleukin-10 gene-592C/A (rs1800872), -819T/C (rs1800871), -1082A/G (rs1800896); Toll-like receptor-2 gene Arg753Gln (rs5743708); Toll-like receptor-4 gene Thr399ile (rs4986791), Asp299Gly (rs4986790); and metalloproteinase-9 gene-8202A/G (rs11697325). The study of polymorphic loci was checked for compliance with the Hardy- Weinberg equilibrium using Fisher's exact test along with the analyses of the frequency of alleles and the genotypes.

RESULTS

The association of diseases with G allele Toll-like receptor-2 gene Arg753Gln (rs5743708) was revealed in irritable bowel syndrome patients with adenomatous polyps of the colon (P < .0006) and AG single-nucleotide polymorphisms s of Toll-like receptor-2 gene (χ2 = 12.78, P < .002); A allele had a protective effect. The AG genotype metalloproteinase-9 gene-8202A/G (rs11697325) polymorphism in irritable bowel syndrome patients with adenomatous polyps of the colon had a protective effect (P < .05). AA genotype interleukin-10 gene-1082A/G (rs1800896) polymorphism in the irritable bowel syndrome patient (χ2 = 33.97, 4.0E-8) can be considered as the risk for adenomatous polyps of the colon in irritable bowel syndrome.

CONCLUSION

G allele Toll-like receptor-2 gene Arg753Gln (rs5743708) and AA genotype interleukin-10 gene-1082A/G (rs1800896) polymorphisms can be the marker of the emergence of adenomatous polyps of the colon concomitant with irritable bowel syndrome.

Investigating Key Targets of Dajianzhong Decoction for Treating Crohn’s Disease Using Weighted Gene Co-Expression Network

Background: Crohn’s disease (CD) is an inflammatory bowel disease, cases of which have substantially increased in recent years. The classical formula Dajianzhong decoction (DD, Japanese: Daikenchuto) is often used to treat CD, but few studies have evaluated related therapeutic mechanisms. In this study, we investigated the potential targets and mechanisms of DD used for treating CD at the molecular level through the weighted gene co-expression network. Methods: The main chemical components of the three DD herbs (Zanthoxylum bungeanum Maxim., Zingiber officinale (Willd.) Rosc., and Ginseng Radix et Rhizoma) were searched for using the HERB database. The targets for each component were identified using the SwissTargetPrediction and HERB databases, whereas the disease targets for CD were retrieved from the GeneCards and DisGeNET databases. The functional enrichment analysis was performed on the common targets of DD and CD. High-throughput sequencing data for CD patients were retrieved from the Gene Expression Omnibus database, and WGCNA was performed to identify the key targets. The association between the key targets and DD ingredients was verified using molecular docking. Results: By analyzing the interaction targets between DD and CD, 196 overlapping genes were identified. The enrichment results indicated that the PI3K-AKT, TNF, MAPK, and IL-17 signaling pathways influenced the mechanism of action of DD in counteracting CD. Combined with WGCNA, four differentially expressed genes (SLC6A4, NOS2, SHBG, and ABCB1) and their corresponding 24 compounds were closely related to the occurrence of CD. Conclusions: By integrating gene co-expression network analysis, this study preliminarily reveals the internal molecular mechanism of DD in treating CD from a systematic perspective, validated by molecular docking. However, these findings require further validation.

Identification of putative transcriptomic biomarkers in irritable bowel syndrome (IBS): Differential gene expression and regulation of TPH1 and SERT by vitamin D

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders and affects approximately 4% of the global population. The diagnosis of IBS can be made based on symptoms using the validated Rome criteria and ruling out commonly occurring organic diseases. Although biomarkers exist for "IBS mimickers" such as celiac disease and inflammatory bowel disease (IBD), no such test exists for IBS. DNA microarrays of colonic tissue have been used to identify disease-associated variants in other gastrointestinal (GI) disorders. In this study, our objective was to identify biomarkers and unique gene expression patterns that may define the pathological state of IBS. Mucosal tissue samples were collected from the sigmoid colon of 29 participants (11 IBS and 18 healthy controls). DNA microarray analysis was used to assess gene expression profiling. Extraction and purification of RNA were then performed and used to synthesize cDNA. Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) was employed to identify differentially expressed genes in patients diagnosed with IBS compared to healthy, non-IBS patient-derived cDNA. Additional testing probed vitamin D-mediated regulation of select genes associated with serotonergic metabolism. DNA microarray analyses led to the identification of 858 differentially expressed genes that may characterize the IBS pathological state. After screening a series of genes using a combination of gene ontological analysis and RT-qPCR, this spectrum of potential IBS biomarkers was narrowed to 23 genes, some of which are regulated by vitamin D. Seven putative IBS biomarkers, including genes involved in serotonin metabolism, were identified. This work further supports the hypothesis that IBS pathophysiology is evident within the human transcriptome and that vitamin D modulates differential expression of genes in IBS patients. This suggests that IBS pathophysiology may also involve vitamin D deficiency and/or an irregularity in serotonin metabolism.

Relationship Between the Onset of Ménière's Disease and Sympathetic Hyperactivity

Objective

The pathogenesis of Ménière's disease is still largely unknown; however, it is known to be strongly associated with stress. Excessive stress can cause hyperactivity of the sympathetic autonomic nervous system. With the aim of understanding changes in sympathetic hyperactivity before and after Ménière's disease, we compared autonomic nervous function in patients in a stable phase of Ménière's disease and that in healthy adults. We also gathered data over about 10 years on autonomic nervous function immediately before a Ménière's attack.

Study Design

Prospective study.

Patients

Autonomic nervous function was analyzed in 129 patients in a stable phase of Ménière's disease 31 healthy adult volunteers. In nine patients, autonomic nervous function was also measured immediately before and after treatment of a vertigo attack.

Main Outcome Measure

Power spectrum analysis of heart rate variability (HRV) of EEG/ECG and an infrared electronic pupillometer were used. Sympathetic and parasympathetic nervous function was measured.

Results

There were no statistically significant differences in autonomic nervous function determined by HRV and electronic pupillometry between patients in a stable phase of Ménière's disease and healthy adults. Sympathetic function as measured by electronic pupillometry parameters VD and T5 showed no difference between the affected and unaffected sides in the baseline data measured in the stable phase (VD: affected side is 31.02 ± 6.16 mm/sec, unaffected side is 29.25 ± 5.73 mm/sec; T5: affected side is 3.37 ± 0.43 msec, unaffected side is 3.25 ± 0.39 msec). In contrast, all nine patients whose HRV data had been obtained just before an attack showed marked suppression of the parasympathetic nervous system and activation of the sympathetic nervous system. Electronic pupillometry also revealed an overactivation of the sympathetic nervous system on the affected side, just before the attacks. Analysis of sequential changes after the onset of an attack revealed that overactivation on the affected side was reduced after treatment, and no difference between affected and unaffected sides was observed 3 days after treatment.

Conclusion

Detailed analysis of autonomic nervous function showed that immediately before an attack of Ménière's disease, the sympathetic nervous system on the affected side was strongly overactivated.

Gut Microbiota-Derived Metabolites in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is the most common functional bowel disorder worldwide and is associated with visceral hypersensitivity, gut motility, immunomodulation, gut microbiota alterations, and dysfunction of the brain-gut axis; however, its pathophysiology remains poorly understood. Gut microbiota and its metabolites are proposed as possible etiological factors of IBS. The aim of our study was to investigate specific types of microbiota-derived metabolites, especially bile acids, short-chain fatty acids, vitamins, amino acids, serotonin and hypoxanthine, which are all implicated in the pathogenesis of IBS. Metabolites-focused research has identified multiple microbial targets relevant to IBS patients, important roles of microbiota-derived metabolites in the development of IBS symptoms have been established. Thus, we provide an overview of gut microbiota and their metabolites on the different subtypes of IBS (constipation-predominant IBS-C, diarrhea-predominant IBS-D) and present controversial views regarding the role of microbiota in IBS.

Familial and Genetic Influences on the Common Pediatric Primary Pain Disorders: A Twin Family Study

The primary pain disorders of childhood are highly prevalent but have infrequently been studied collectively. Genetic influences have been suggested to be causally implicated. Surveys were sent to 3909 Australian twin families, assessing the lifetime prevalence of growing pains, migraine, headache, recurrent abdominal pain, low back pain, and persistent pain (not otherwise specified) in pediatric twins and their immediate family members. Comparisons between monozygous (MZ) and dizygous (DZ) twin pair correlations, concordances and odds ratios were performed to assess the contribution of additive genetic influences. Random-effects logistic regression modelling was used to evaluate relationships between twin individuals and their co-twins, mothers, fathers and oldest siblings with the subject conditions. Twin analyses of responses from 1016 families revealed significant influence of additive genetic effects on the presence of growing pains, migraine, and recurrent abdominal pain. The analyses for headache, low back pain, and persistent pain overall did not conclusively demonstrate that genetic influences were implicated more than shared environmental factors. Regression analyses demonstrated varying levels of significance in relationships between family members and twin individuals for the tested conditions, with strongest support for genetic influences in growing pains and migraine. These data, together with previously published association analyses, suggest common causal influences including genes.

Food-specific serum IgG and symptom reduction with a personalized, unrestricted-calorie diet of six weeks in Irritable Bowel Syndrome (IBS)

Background

Irritable Bowel Syndrome (IBS) is a widespread disease with variable symptoms that have an important impact on the quality of life. Despite the prevalence of IBS, its etiology and pathophysiology are still to be fully understood, but immune response is known to be involved. In this study, we investigated the variation of two specific cytokines, B-cell activating factor (BAFF) and platelet-activating factor (PAF), the levels of food-specific IgG and the symptom severity, using Irritable Bowel Syndrome—Symptom Severity Score (IBS-SSS), following a personalized and unrestricted-calorie diet.

Methods

We enrolled 30 subjects with diagnosis of IBS, according to Rome-IV criteria, whose inflammatory markers were measured at baseline and after 6 weeks of dietary intervention. The subjects were monitored in a general practice outpatient setting and nutritional advice was offered remotely via two telephone sessions with a nutritionist.

Results

BAFF and PAF values did not differ between baseline and end of study, both in compliant (C) and non-compliant (NC) subjects. IgG levels significantly decreased only in compliant subjects: 37.32 (23.24–93.67) IU/mL; 27.9 (7.56–93.96) IU/mL (p = 0.02) and in non-compliant went from 51.83 (13.17–113.1) IU/mL to 44.06 (4.96–255.4) IU/mL (p = 0.97, ns). IBS-SSS significantly decreased in both compliant subjects, from 245 (110–480) to 110 (0–140) (p < 0.0001), and non compliant subjects, from 250 (155–370) to 100 (7–220) (p < 0.0001). Comparing IBS-SSS between week 3 and week 6, only compliant subjects had a significant reduction, from 155 (50–355) to 110 (0–140) (p = 0.005), versus non-compliant, from 115 (35–315) to 100 (7–220) (p = 0.33, ns).

Conclusion

These findings support the rapid efficacy and suitability of a personalized dietetic intervention with outside consultation in IBS.

Trial registration: ClinicalTrials.gov ID NCT04348760 Registered April 15, 2020 (retrospectively registered) https://clinicaltrials.gov/show/NCT04348760

The trace aminergic system: a gender-sensitive therapeutic target for IBS?

Due to a lack of specific or sensitive biomarkers, drug discovery advances have been limited for individuals suffering from irritable bowel syndrome (IBS). While current therapies provide symptomatic relief, inflammation itself is relatively neglected, despite the presence of chronic immune activation and innate immune system dysfunction. Moreover, considering the microgenderome concept, gender is a significant aetiological risk factor. We believe that we have pinpointed a "missing link" that connects gender, dysbiosis, diet, and inflammation in the context of IBS, which may be manipulated as therapeutic target. The trace aminergic system is conveniently positioned at the interface of the gut microbiome, dietary nutrients and by-products, and mucosal immunity. Almost all leukocyte populations express trace amine associated receptors and significant amounts of trace amines originate from both food and the gut microbiota. Additionally, although IBS-specific data are sparse, existing data supports an interpretation in favour of a gender dependence in trace aminergic signalling. As such, trace aminergic signalling may be altered by fluctuations of especially female reproductive hormones. Utilizing a multidisciplinary approach, this review discusses potential mechanisms of actions, which include hyperreactivity of the immune system and aberrant serotonin signalling, and links outcomes to the symptomology clinically prevalent in IBS. Taken together, it is feasible that the additional level of regulation by the trace aminergic system in IBS has been overlooked, until now. As such, we suggest that components of the trace aminergic system be considered targets for future therapeutic action, with the specific focus of reducing oxidative stress and inflammation.

Prospects for the use of biomarkers in the diagnosis of irritable bowel syndrome

Irritable bowel syndrome is a chronic functional disorder of the intestine, manifested by altered intestinal habits and recurrent abdominal pain in combination with two or more criteria: association with defecation, association with a change in the frequency of defecation, association with a change in the appearance of the stool. To date, IBS remains a diagnosis of exclusion that needs to be differentiated from a wide range of organic diseases. In recent years, a large number of publications have appeared on the research of etiopathogenesis, diagnosis and treatment of IBS. This literary review highlights the problems of searching for biomarkers of IBS as a way to solve the problem of diagnosis of this pathology and understanding the causes of its occurrence.

Ethnic differences in genetic polymorphism associated with irritable bowel syndrome

Genetic polymorphism is associated with irritable bowel syndrome (IBS) in terms of susceptibility and clinical manifestations. Previous studies have shown that genetic polymorphism might play a key role in the onset and progression of IBS by modulating components of its pathogenesis such as the gut-brain axis, gastrointestinal motility, inflammatory activity, and immune status. Although underlying pathophysiological mechanisms have not been fully clarified, the potential ethnic differences that are present in worldwide genetic studies of IBS deserve attention. This review surveyed numerous studies focusing on IBS-associated single nucleotide polymorphisms, and investigated the ethnic disparities revealed by them. The results demonstrate the need for more attention on ethnic factors in IBS-related genetic studies. Taking ethnic backgrounds into accounts and placing emphasis on disparities potentially ascribed to ethnicity could help lay a solid and generalized foundation for transcultural, multi-ethnic, or secondary analyses in IBS, for example, a meta-analysis. Broader genetic studies considering ethnic factors are greatly needed to obtain a better understanding of the pathophysiological mechanisms of IBS and to improve the prevention, intervention, and treatment of this disease.

Gut Microbial Metabolites and Biochemical Pathways Involved in Irritable Bowel Syndrome: Effects of Diet and Nutrition on the Microbiome

The food we consume and its interactions with the host and their gut microbiota affect normal gut function and health. Functional gut disorders (FGDs), including irritable bowel syndrome (IBS), can result from negative effects of these interactions, leading to a reduced quality of life. Certain foods exacerbate or reduce the severity and prevalence of FGD symptoms. IBS can be used as a model of perturbation from normal gut function with which to study the impact of foods and diets on the severity and symptoms of FGDs and understand how critical processes and biochemical mechanisms contribute to this impact. Analyzing the complex interactions between food, host, and microbial metabolites gives insights into the pathways and processes occurring in the gut which contribute to FGDs. The following review is a critical discussion of the literature regarding metabolic pathways and dietary interventions relevant to FGDs. Many metabolites, for example bile acids, SCFAs, vitamins, amino acids, and neurotransmitters, can be altered by dietary intake, and could be valuable for identifying perturbations in metabolic pathways that distinguish a "normal, healthy" gut from a "dysfunctional, unhealthy" gut. Dietary interventions for reducing symptoms of FGDs are becoming more prevalent, but studies investigating the underlying mechanisms linked to host, microbiome, and metabolite interactions are less common. Therefore, we aim to evaluate the recent literature to assist with further progression of research in this field.

The Evolving Role of Gut Microbiota in the Management of Irritable Bowel Syndrome: An Overview of the Current Knowledge

The intestinal microbiota is one of the most rapidly evolving areas in biology and medicine. Extensive research in the last decade has escalated our understanding of the role of the microbiota in the pathogenesis of several intestinal and extra-intestinal disorders. Marked by high prevalence, substantial morbidity, and enormous costs, irritable bowel syndrome (IBS) is an important chronic gastrointestinal disorder that is widely encountered by gastroenterologists. Despite advances in our understanding of its pathophysiology, curative interventions have yet to be discovered, and therapeutic approaches remain symptom-driven. Recently, accumulating evidence has enlightened the possible impact of an imbalanced gut microbiome in the pathogenesis of IBS. In fact, several studies have documented altered microbiota in patients, while others have shown that IBS severity was associated with a distinct microbiota signature. These findings may pave the way for the use of microbiota manipulation strategies as an attractive option for IBS management, and may have an essential role in efforts to reduce the societal and economic effects of this ever-growing disorder. In this review, we have outlined the results of the latest research on the association between microbiota and IBS and their implications for the clinical management of affected patients.

Induction of brain-derived neurotrophic factor in enteric glial cells stimulated by interleukin-1β via a c-Jun N-terminal kinase pathway

Brain-derived neurotrophic factor exhibits neurotropic and neuroprotective functions and is increased in the colonic mucosa of patients with irritable bowel syndrome in correlation with the severity and frequency of abdominal pain. However, there are no reports of brain-derived neurotrophic factor expression in enteric glial cells. We evaluated the mRNA and protein expressions of brain-derived neurotrophic factor in enteric glial cells and culture medium and levels of mitogen-activated protein kinase after stimulation with interleukin-1β. Brain-derived neurotrophic factor mRNA expression was increased by interleukin-1β (3.125-75 ng/ml) and time-dependently increased 3-fold (24 h) and 4-fold (48 h) by interleukin-1β (50 ng/ml). Pro- and mature brain-derived neurotrophic factor proteins were both significantly increased at 48 h by interleukin-1β. However, the mature form was predominant in the cultured medium. Interleukin-1β increased phosphorylated-p38 mitogen-activated protein kinase expressions 2-fold higher at 5 and 15 min, and also phosphorylated-c-Jun N-terminal kinase expression 5-fold at 5 min and 10-fold at 15 min. Prior treatment with phosphorylated-c-Jun N-terminal kinase inhibitors decreased interleukin-1β-induced brain-derived neurotrophic factor by 50%. Thus, brain-derived neurotrophic factor expression was induced by interleukin-1β in enteric glial cells via a phosphorylated-c-Jun N-terminal kinase pathway, which might affect the enteric nervous system during stress.

Gut Microbial Dysbiosis in the Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Case-Control Studies

BACKGROUND

Irritable bowel syndrome (IBS) is the most common functional digestive condition in the industrialized world. The gut microbiota plays a key role in disease pathogenesis.

OBJECTIVE

A systematic review and meta-analysis on case-control studies was conducted to determine whether there is gut microbial dysbiosis in participants with IBS in comparison with healthy controls and, if so, whether the dysbiosis pattern differs among IBS subtypes and geographic regions.

METHODS

This review was conducted and reported according to the MOOSE (Meta-Analysis of Observational Studies in Epidemiology) 2000 and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2009 guidelines. Research articles published up to May 9, 2018 were identified through MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (Cochrane Library), ClinicalTrials.gov, EMBASE, and Web of Science. Study quality was assessed using the Newcastle-Ottawa Scale. Case-control studies of participants with IBS who had undergone quantitative gut microbial stool analysis were included. The primary exposure measure of interest is log₁₀ bacterial counts per gram of stool. Meta-analyses were performed to estimate the mean difference (MD) in gut microbiota between participants with IBS and healthy controls using the random-effects model with inverse variance in Revman 5.3 and R 3.5.1. Publication bias was assessed with funnel plots and Egger's test. Between-study heterogeneity was analyzed using Higgins I² statistic with 95% CIs.

RESULTS

There were 6,333 unique articles identified; 52 qualified for full-text screening. Of these, 23 studies were included for analysis (n=1,340 participants from North America, Europe, and Asia). Overall, the studies were moderate in quality. Comparing participants with IBS to healthy controls, lower fecal Lactobacillus (MD= -0.57 log₁₀ colony-forming unit [CFU]/g; P<0.01) and Bifidobacterium (MD= -1.04 log₁₀CFU/g; P<0.01), higher Escherichia coli (MD=0.60 log₁₀CFU/g; P<0.01), and marginally higher Enterobacter (MD=0.74 log₁₀CFU/g; P=0.05). No difference was found between participants with IBS and healthy controls in fecal Bacteroides and Enterococcus (P=0.18 and 0.68, respectively). Publication bias was not observed except in Bifidobacterium (P=0.015). Subgroup analyses on participants with diarrhea-predominant and constipation-predominant IBS showed consistent results with the primary results. A subgroup analysis of Chinese studies was consistent with the primary results, except for fecal Bacteroides, which was increased in participants with IBS vs healthy controls (MD=0.29; 95% CI 0.13 to 0.46; P<0.01). Although substantial heterogeneity was detected (I²>75%) in most comparisons, the direction of the effect estimates is relatively consistent across studies.

CONCLUSIONS

IBS is characterized by gut microbial dysbiosis. Prospective, large-scale studies are needed to delineate how gut microbial profiles can be used to guide targeted therapies in this challenging patient population.

Methane and Constipation-predominant Irritable Bowel Syndrome: Entwining Pillars of Emerging Neurogastroenterology

Functional gut disorders have long known to cause depravity in quality of life. Among the group of these heterogeneous disorders, irritable bowel syndrome (IBS) has been known to affect a large chunk of our population. IBS is not as simple as it sounds. Caused by a multitude of factors, the heterogeneity of this disorder has laid the foundation for research and the new principles of neurogastroenterology. Dysbiosis and methane production are one of the forthcoming factors that are currently under investigation. Down the road of exclusive enteric anaerobic fermentation of polysaccharides, methane is produced. It was considered to be an inert gas in the past, with little to no role in gut activity but now it is established that it has an impressive role in the etiology of constipation-predominant IBS (C-IBS). Acting as a neurotransmitter, it is known to affect ileal and colonic transit time, which has currently been shown in animal studies. Many laxatives, ionophore antibiotics, drugs like rifamixin and neomycin have been targeted against this very principle. Lately, lovastatin has emerged as a potential pharmacologic therapy to devoid the gut of methane without disrupting the gut niche in itself and has shown promise in relieving the symptoms of C-IBS. The goal of this article is to compile and assemble the literature available on IBS and the neuromodulation of methane to teach physicians and research scientists about the current age of gastroenterology and the growing need to emphasize the role of methane in the symptomatology of functional gut disorders like C-IBS.

Irritable bowel syndrome and colonic diverticular disease: overlapping symptoms and overlapping therapeutic approaches

PURPOSE OF REVIEW

Irritable bowel syndrome (IBS) is a common symptomatic disorder in the Western world and colonic diverticula are also prevalent; however, relationships between IBS-type symptoms and diverticula have been a source of much debate. Our goal was to reassess these relationships in the light of new data.

RECENT FINDINGS

On removing from consideration clinical scenarios which are directly related to diverticula (i.e., diverticulitis, diverticular hemorrhage, and complications of diverticulitis, such as stricture and fistula), relationships between IBS and diverticula can be seen to revolve around a number of questions. First, are IBS and symptomatic uncomplicated diverticular disease (SUDD) the same condition? Or, in other words is SUDD no more than IBS in an individual who just happens to have diverticula? Although coincident IBS and diverticula inevitably do occur there is some evidence to indicate that SUDD may be somewhat distinctive with SUDD being characterized by more frequent and severe pain. Second, and analogous to interactions between IBS and inflammatory bowel disease or celiac disease, can an episode of acute diverticulitis lead to the de novo development of IBS? There is now epidemiological and pathophysiological evidence to support this occurrence.

SUMMARY

Although relationships between uncomplicated diverticular disease and IBS have been reexamined their status remains unclear. As yet, however, none of the newer concepts related to this relationship have led to new therapeutic approaches in IBS or diverticular disease.

Adipose Tissue-Derived Biomarkers of Intestinal Barrier Functions for the Characterization of Diarrhoea-Predominant IBS

Background

Alterations of the small-intestinal permeability (s-IP) might play an essential role in a subgroup of diarrhoea-predominant IBS (D-IBS) patients.

Goals

(a) To analyse in D-IBS patients the symptom profile in relation to the altered (+) or not (−) s-IP using the Gastrointestinal Symptom Rating Scale (GSRS). (b) To assess the circulating levels of the adipokines IL-6, IL-8, TNF-α, leptin, and adiponectin, along with LPS, TLR-4, neurotensin, and brain-derived neurotrophic factor (BDNF). The frequency distribution of SNPs at the loci for the investigated molecules and leptin receptor was evaluated.

Study

The study included 34 D-IBS patients and 17 healthy controls (HC). s-IP permeability was assayed by high-performance liquid chromatography determination in the urine of the lactulose to mannitol ratio. Concentrations of IL-6, IL-8, TNF-α, LPS, TLR-4, leptin, adiponectin, neurotensin, and BDNF were assayed by ELISA. Screening of genetic variants was done employing the restriction fragment length polymorphism-polymerase chain reaction method.

Results

D-IBS(−) patients had a significantly higher GSRS cluster pain and diarrhoea profile than D-IBS(+) ones. Significant correlations were found between the symptoms clusters and immune activation and inflammation markers. The levels of adipo(cyto)kines in D-IBS(+) patients were higher than those of controls, and IL-6 levels correlated with those of LPS. Leptin and BDNF were significantly higher, and neurotensin levels were significantly lower in D-IBS(+) than in controls. No differences were found in the frequency distribution of genotypes among the study groups.

Conclusions

Results from this study could be of some help in the characterization of the D-IBS and highlight the contribution of an altered intestinal barrier in the pathogenesis of this syndrome. Besides, a role could be ascribed to molecules secreted by the visceral adipose tissue that can impact on barrier functions.

The Role of Diet in the Treatment of Irritable Bowel Syndrome: A Systematic Review

Irritable bowel syndrome (IBS) is a multifaceted illness involving maladaptive shifts in the gut microbiota that affect the enteric nervous and immune systems, mucosal barrier function, the balance of neurotransmitters and hormones, and emotional well-being. There is abundant evidence indicating that certain foods elicit symptoms in IBS. Numerous elimination-type diets have been shown to alleviate symptoms. However, among these, the most controversial is a group of foods called fructo, oligo-, di-, and monosaccharides and polyols (FODMAPs). This paper reviews the role of diet and systematically analyze the literature for the role of FODMAPs in IBS.

Pain self-management plus nurse-led support in young adults with irritable bowel syndrome: Study protocol for a pilot randomized control trial

Irritable bowel syndrome (IBS) is a functional gut disorder that typically manifests in early adult years. IBS patients report that pain is the most distressing symptom with the greatest impact on quality of life. Pain-sensitivity genes and the gut microbiome may influence severity of symptoms as well as response to self-management (SM) interventions. Based on current understanding of the science of SM, pain neurophysiology, and the gut-brain axis, our team developed a pain SM intervention to be added to evidence-based self-management instruction to increase the individual's SM knowledge and skills (self-efficacy, self-regulation, and goal-setting). The purpose of this randomized controlled longitudinal pilot study is to examine the feasibility, acceptability, and preliminary effectiveness of the IBS-pain SM intervention on IBS-pain SM behaviors and related health outcomes. A sample of 80 young adults (age 18-29 years old) will be recruited and randomly assigned to the experimental or control group. Both groups will receive 10 electronic video modules focused on IBS-pain SM knowledge and skills. The experimental group also will receive nurse-led one-on-one phone consultations to facilitate monitoring and problem-solving. All participants will be followed over 12 weeks. Primary outcomes will be measured at baseline, 6 weeks, and 12 weeks, including IBS-pain SM behaviors, quality of life, and well-being. The influence of pain-sensitivity genes and the gut microbiome on IBS-pain SM behaviors and health outcomes also will be assessed.

The TPH1 rs211105 gene polymorphism affects abdominal symptoms and quality of life of diarrhea-predominant irritable bowel syndrome

The gastrointestinal symptoms of irritable bowel syndrome are strongly related to impaired quality of life (QOL), especially in diarrhea-predominant. The gene polymorphisms associated with serotonin, or 5-hydroxytryptamine, alter gastrointestinal symptoms and mental status. We aimed to evaluate the effects of gene polymorphisms on gastrointestinal symptoms, psychological conditions, and QOL, and compare these between patients with diarrhea-predominant irritable bowel syndrome (n = 62) and healthy controls (n = 64). The gene polymorphisms of 5-HTTLPR, 5-HTTVNTR, TPH1 rs453773, and TPH1 rs211105 were evaluated. Gastrointestinal symptoms, depressive state, and QOL were assessed using the Gastrointestinal Symptom Rating Scale, Self-rating Depression Scale, and Short-Form-36. Gene polymorphisms did not significantly differ in frequency between the two groups. The scores for diarrhea, abdominal pain, and indigestion significantly correlated with the physical component summary score. Only the group of patients with diarrhea-predominant irritable bowel syndrome showed a significant correlation between the TPH1 rs211105 T/T genotype and lower scores for role physical and mental health, and higher scores for indigestion and diarrhea. 5-HTTLPR l/s was associated with lower score of role emotional in the diarrhea-predominant irritable bowel syndrome and higher scores in the controls. The gene polymorphisms of 5-hydroxytryptamine signaling effected gastrointestinal symptoms and QOL, especially of the patients with diarrhea-predominant irritable bowel syndrome.

Epidemiological and clinical perspectives on irritable bowel syndrome in India, Bangladesh and Malaysia: A review

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder, common in clinic and in the community. It has a significant impact on both society and patients' quality of life. The epidemiology, clinical presentation, and management of IBS may vary in different geographical regions due to differences in diet, gastrointestinal infection, socio-cultural and psycho-social factors, religious and illness beliefs, symptom perception and reporting. Although previous reviews and consensus reports on IBS in Asia have been published, Asia is quite diverse socio-demographically. In this context, India, Bangladesh and Malaysia share some similarities, including: (1) large proportion of the population living in rural areas; (2) rapid development and associated lifestyle changes in urban areas; and (3) dietary, cultural and religious practices. The present review explores the clinical and epidemiological data on IBS from these three major nations in South and South-East Asia. In-depth review of the literature revealed important differences between IBS in the East, as revealed by studies from these three countries, and the West; these include a predominantly rural profile, differences in bowel habit and symptom profile, raising concern with regards to diagnostic criteria and subtyping of IBS, higher dietary fiber consumption, frequent lactose malabsorption, parasitosis, and possible overlap between post-infectious IBS and tropical sprue. Moreover, the current perception on difference in prevalence of the disorder in these countries, as compared to the West, might be related to variation in survey methods.

Colonic Transit Time and Gut Peptides in Adult Patients with Slow and Normal Colonic Transit Constipation

PURPOSE

To investigate whether pathophysiological differences exist among healthy controls (HC) and patients with slow and normal transit constipation (STC and NTC), we evaluated (1) gastrointestinal (GI) symptoms using validated questionnaires; (2) circulating concentrations of neurotensin, motilin, corticotrophin-releasing factor (CRF), and somatostatin; and (3) possible differences in frequency distribution of the neurotensin rs1800832 A/G and Neurotensin Receptor 1 rs6090453 C/G SNPs.

METHODS

Fifty-one patients with severe functional constipation and 20 HC completed the study. Symptoms were evaluated by GSRS and Constipaq scoring system. Plasma concentrations of GI peptides were evaluated by ELISA on fasting and six sequential blood samples after a standard meal. Genotyping was performed by PCR and endonuclease digestion.

RESULTS

Symptom profiles largely overlapped between NTC and STC patients. As for peptide profiles, neurotensin showed lower concentrations at 60 and 90 min in STC versus HC, and motilin showed throughout the curve 85% and 82% lower levels in STC than HC and NTC, respectively. Finally, neurotensin polymorphism resulted in being associated with the peptide levels.

CONCLUSIONS

Symptom profile is not a reliable tool to discriminate STC, whilst the GI peptide profiles might help in identifying it.

Serotonin-Related Gene Variants in Patients with Irritable Bowel Syndrome and Depressive or Anxiety Disorders

AIM

To assess the association of six polymorphisms in serotonin-related genes with depressive or anxiety disorders in patients with irritable bowel syndrome (IBS).

METHODS

The lifetime prevalence of depressive and anxiety disorders was assessed in 95 IBS patients (85% women) using the Munich version of the Composite International Diagnostic Interview (CIDI). IBS was diagnosed according to the Rome III criteria. SCL6A4 HTTLPR polymorphism (rs4795541) was determined using PCR-based method. Single-nucleotide polymorphisms in HTR1A (rs6295), HTR2A (rs6313 and rs6311), HTR2C (rs6318), and TPH1 (rs1800532) were detected by minisequencing method.

RESULTS

IBS patients with depressive disorders were characterized by higher frequency of 5-HTTLPR L allele in comparison to IBS patients with anxiety disorders. The lower frequency of 1438 A allele in HTR2A was found in IBS patients with depressive disorders in comparison to IBS patients without mental disorders. The lower G allele frequency in HTR2C rs6318 polymorphism among IBS patients with anxiety disorders was also observed.

CONCLUSIONS

Our results provide further evidence for the involvement of SLC6A4 rs4795541 and HTR2A rs6311 polymorphisms in the pathophysiology of depressive disorders in IBS patients. The new findings indicate that HTR2C rs6318 polymorphism may be associated with the susceptibility to anxiety disorders in IBS patients.

COMT Val158Met Polymorphism and Symptom Improvement Following a Cognitively Focused Intervention for Irritable Bowel Syndrome

BACKGROUND

Our nurse-delivered comprehensive self-management (CSM) program, a cognitive behavioral therapy intervention, is effective in reducing gastrointestinal and psychological distress symptoms in patients with irritable bowel syndrome (IBS). Findings from non-IBS studies indicate that the catechol-O-methyltransferase (COMT) Val158Met polymorphism may moderate the efficacy of cognitive behavioral therapy. It is unknown whether this COMT polymorphism is associated with symptom improvements in patients with IBS.

OBJECTIVE

We tested whether this COMT Val158Met polymorphism influences the efficacy of our 2-month CSM intervention.

METHODS

We analyzed data from two published randomized controlled trials of CSM. The combined European American sample included 149 women and 23 men with IBS (CSM, n = 111; usual care [UC], n = 61). The primary outcomes were daily reports of abdominal pain, depression, anxiety, and feeling stressed measured 3 and 6 months after randomization. Secondary outcomes were additional daily symptoms, retrospective psychological distress, IBS quality of life, and cognitive beliefs about IBS. The interaction between COMT Val158Met polymorphism and treatment group (CSM vs. UC) in a generalized estimating equation model tested the main objective.

RESULTS

At 3 months, participants with at least one Val allele benefited more from CSM than did those with the Met/Met genotype (p = .01 for anxiety and feeling stressed, and p < .16 for abdominal pain and depression). The moderating effect of genotype was weaker at 6 months.

DISCUSSION

Persons with at least one Val allele may benefit more from CSM than those homozygous for the Met allele. Future studies with larger and more racially diverse samples are needed to confirm these findings.

RCT REGISTRATION

Parent studies were registered at ClinicalTrials.gov (NCT00167635 and NCT00907790).

Expression of long non-coding RNAs in autoimmunity and linkage to enhancer function and autoimmune disease risk genetic variants

Genome-wide association studies have identified numerous genetic variants conferring autoimmune disease risk. Most of these genetic variants lie outside protein-coding genes hampering mechanistic explorations. Numerous mRNAs are also differentially expressed in autoimmune disease but their regulation is also unclear. The majority of the human genome is transcribed yet its biologic significance is incompletely understood. We performed whole genome RNA-sequencing [RNA-seq] to categorize expression of mRNAs, known and novel long non-coding RNAs [lncRNAs] in leukocytes from subjects with autoimmune disease and identified annotated and novel lncRNAs differentially expressed across multiple disorders. We found that loci transcribing novel lncRNAs were not randomly distributed across the genome but co-localized with leukocyte transcriptional enhancers, especially super-enhancers, and near genetic variants associated with autoimmune disease risk. We propose that alterations in enhancer function, including lncRNA expression, produced by genetics and environment, change cellular phenotypes contributing to disease risk and pathogenesis and represent attractive therapeutic targets.

Irritable bowel syndrome is concentrated in people with higher educations in Iran: an inequality analysis

OBJECTIVES

Like any other health-related disorder, irritable bowel syndrome (IBS) has a differential distribution with respect to socioeconomic factors. This study aimed to estimate and decompose educational inequalities in the prevalence of IBS.

METHODS

Sampling was performed using a multi-stage random cluster sampling approach. The data of 1,850 residents of Kish Island aged 15 years or older were included, and the determinants of IBS were identified using a generalized estimating equation regression model. The concentration index of educational inequality in cases of IBS was estimated and decomposed as the specific inequality index.

RESULTS

The prevalence of IBS in this study was 21.57% (95% confidence interval [CI], 19.69 to 23.44%). The concentration index of IBS was 0.20 (95% CI, 0.14 to 0.26). A multivariable regression model revealed that age, sex, level of education, marital status, anxiety, and poor general health were significant determinants of IBS. In the decomposition analysis, level of education (89.91%), age (−11.99%), and marital status (9.11%) were the three main contributors to IBS inequality. Anxiety and poor general health were the next two contributors to IBS inequality, and were responsible for more than 12% of the total observed inequality.

CONCLUSIONS

The main contributors of IBS inequality were education level, age, and marital status. Given the high percentage of anxious individuals among highly educated, young, single, and divorced people, we can conclude that all contributors to IBS inequality may be partially influenced by psychological factors. Therefore, programs that promote the development of mental health to alleviate the abovementioned inequality in this population are highly warranted.

Randomised clinical trial: exploratory phase 2 study of ONO-2952 in diarrhoea-predominant irritable bowel syndrome

BACKGROUND

ONO-2952 is a novel and selective inhibitor of translocator protein 18 kDa that reduces stress-induced defecation and visceral hyperalgesia in rat models.

AIM

To evaluate the efficacy and safety of ONO-2952 in females with irritable bowel syndrome with diarrhoea in an exploratory proof-of-concept study.

METHODS

A randomised, double-blind, placebo-controlled study was conducted at 49 US centres. Two hundred subjects with irritable bowel syndrome with diarrhoea (Rome III criteria) were randomised to ONO-2952 20 mg, or 60 mg, or placebo. Subjects recorded irritable bowel syndrome symptoms daily during a 2-week baseline period, the 4-week treatment period and for 4 weeks post-treatment. The co-primary endpoints were change from baseline to week 4 in abdominal pain, stool consistency and stool frequency.

RESULTS

Improvements in irritable bowel syndrome symptoms were seen with ONO-2952 over placebo in per-protocol analyses for all three co-primary endpoints, but these did not reach statistical significance at the 5% level. The largest improvement was seen with ONO-2952 60 mg. ONO-2952 was well tolerated with a safety profile similar to that of placebo. Most adverse events were mild or moderate in severity and not treatment related.

CONCLUSION

ONO-2952 showed evidence of clinical efficacy in reducing irritable bowel syndrome-related symptoms in female subjects with irritable bowel syndrome with diarrhoea, and further evaluation is, therefore, warranted to assess its potential as a treatment for irritable bowel syndrome with diarrhoea (NCT01844180).

The overlap of upper functional gastrointestinal disorders with irritable bowel syndrome in Chinese outpatients: A multicenter study

BACKGROUND AND AIM

Irritable bowel syndrome (IBS) is a common functional bowel disease, and the overlap with upper functional gastrointestinal disorders (FGIDs) is popular. However, the coexistent upper GI symptom profiles, upper FGID spectra, and related risk factors among IBS subjects remain unclear in mainland of China.

METHODS

Consecutive patients from the outpatient gastroenterology clinics of three tertiary hospitals in China were enrolled in this multicenter study. All upper GI symptoms occurring at least once a week in the last 3 months were recorded. Diagnostic criteria of functional esophageal, gastroduodenal disorders and IBS were based on Rome III criteria. Risk factors were assessed using a multivariate logistic regression model.

RESULTS

Of the 8906 consecutive patients, 751 patients met Rome III criteria for IBS and 735 IBS patients participated in the interview. Postprandial fullness (30.6%), belching (27.1%), and regurgitation (21.8%) were the three most prevalent upper GI symptoms in IBS. Functional dyspepsia (FD, 36.7%), belching disorders (27.1%), and functional heartburn (16.3%) were the three most frequent upper FGID in IBS patients. Female sex, divorced or widowed versus married status, defecation straining, reduced bowel movement, mixed IBS, abdominal distention, mild abdominal pain, moderate discomfort were positively associated with IBS-FD overlap. Female sex, drinking, moderate discomfort, and mild to moderate distension were independent risk factors for IBS-belching disorder overlap.

CONCLUSIONS

The study provides detailed overlap spectra of upper FGID with IBS. Mixed IBS is an important risk factor for IBS-FD overlap, which deserved more concern.

Factors influencing health related quality of life in army cadres with irritable bowel syndrome in Chongqing

AIM

To assess the depressive state and health related quality of life (HRQOL) in army cadres with irritable bowel syndrome (IBS) in Chongqing, and to identify the factors influencing health related quality of life.

METHODS

The Self-rating Depression Scale (SDS) was used to assess the degree of depression in Army cadres with IBS in Chongqing, and the SF-36 scale was used to assess the HRQOL. One-way analysis of variance and stepwise regression analysis were used to identify the factors influencing HRQOL.

RESULTS

Analysis of SDS scores showed that there were 125 persons with depressive symptoms (60.1%), including mild depression in 69 (33.1%) patients, moderate depression in 39 (18.7%), and severe depression 17 (8.1%). Stepwise regression analysis showed that SDS score, spicy diet, age, sex, treatment, education, administrative level, physical exercise, smoking and alcohol consumption significantly influenced the HRQOL scores of patients with IBS. Treatment, SDS score, physical exercise, age and spicy diet were main influencing factors with unstandardized partial coefficients of 19.34, -17.22, 15.74, -12.24 and -10.65, respectively.

CONCLUSION

Most of army cadres with IBS in Chongqing suffered from depressive symptoms, and their HRQOL scores were not satisfactory. More attention must be paid to elderly persons, those with higher education, leaders and women. Quitting spicy food, quitting smoking and drinking, pharmaceutical treatment, psychological counseling and physical exercise can improve patients' HRQOL.

GENETIC TRIGGERS AND NEUROHUMORAL MESSENGERS OF POSTOPERATIVE INTESTINAL PARESIS, ITS VALUE IN PREDICTION, PREVENTION AND TREATMENT

The aim of research: to study the causes and mechanisms of postoperative intestinal paresis on the base of assessment of genetic determinism of neurohormonal processes which regulate the contractile ability of the intestines, to determine their role for the choice of treatment tactics. The study presents data about connection between variants of SERT gene, which regulates the reuptake of serotonin, and its concentration in blood plasma and the probability of occurrence of postoperative intestinal paresis. This made it possible not only to predict the occurrence of postoperative disorders of motor-evacuation function of the intestines, but also to improve the algorithms of prevention and pathogenetic based treatment.