Irritable bowel syndrome: a review and update

Neuromodulation and the Gut-Brain Axis: Therapeutic Mechanisms and Implications for Gastrointestinal and Neurological Disorders

The gut-brain axis (GBA) represents a complex, bidirectional communication network that intricately connects the gastrointestinal tract with the central nervous system (CNS). Understanding and intervening in this axis opens a pathway for therapeutic advancements for neurological and gastrointestinal diseases where the GBA has been proposed to play a role in the pathophysiology. In light of this, the current review assesses the effectiveness of neuromodulation techniques in treating neurological and gastrointestinal disorders by modulating the GBA, involving key elements such as gut microbiota, neurotrophic factors, and proinflammatory cytokines. Through a comprehensive literature review encompassing PubMed, Google Scholar, Web of Science, and the Cochrane Library, this research highlights the role played by the GBA in neurological and gastrointestinal diseases, in addition to the impact of neuromodulation on the management of these conditions which include both gastrointestinal (irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and gastroesophageal reflux disease (GERD)) and neurological disorders (Parkinson's disease (PD), Alzheimer's disease (AD), autism spectrum disorder (ASD), and neuropsychiatric disorders). Despite existing challenges, the ability of neuromodulation to adjust disrupted neural pathways, alleviate pain, and mitigate inflammation is significant in improving the quality of life for patients, thereby offering exciting prospects for future advancements in patient care.

Prevalence of Anti- Saccharomyces Cerevisiae Antibodies (ASCA) in Patients With Irritable Bowel Syndrome (IBS). A Case-control Study

BACKGROUND

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction that affects patients' quality. Recent research has shown variations in the mycobiome of individuals with IBS, particularly involving Saccharomyces cerevisiae , and its association with dysbiosis and visceral hypersensitivity. However, the role of Anti-Saccharomyces cerevisiae antibodies (ASCA) in IBS remains unclear, despite their significance as markers of disease severity in inflammatory bowel disease.

OBJECTIVE

This study aimed to investigate the role of ASCA in Mexican IBS patients compared with healthy controls (HCs) and determine whether these antibodies could help differentiate between IBS patients and healthy individuals.

METHODS

Serum samples from 400 IBS patients and 400 HC were analyzed. ASCA IgG levels were measured using enzyme-linked immunosorbent assay (ELISA). The IBS patients were further categorized into subtypes: constipation predominant (IBS-C), diarrhea predominant (IBS-D), and mixed (IBS-M).

RESULTS

Among the participants, 66 IBS patients (16.5%) and 63 HC (15.75%) tested positive for ASCA IgG. No significant difference was observed in ASCA IgG levels between the 2 groups ( P value: 0.8451). The prevalence of ASCA IgG positivity was 14.5% in IBS-C, 17.8% in IBS-D, and 15.9% in IBS-M.

CONCLUSION

Surprisingly, a high prevalence of ASCA IgG was found in the HC group in Mexico. Furthermore, there was no significant difference in ASCA IgG levels between IBS patients and controls. These findings suggest that ASCA is not useful as a discriminatory biomarker for distinguishing IBS patients from healthy individuals and cannot serve as a surrogate marker for visceral hypersensitivity.

Comparing the effectiveness of transdiagnostic treatment with acceptance and commitment therapy on emotional disorders, rumination, and life satisfaction in patients with irritable bowel syndrome: a randomized clinical trial

OBJECTIVE

The present study was conducted to compare the effectiveness of transdiagnostic treatment (UP) with the acceptance and commitment therapy (ACT) on the emotional disorders, rumination, and life satisfaction in the patients with irritable bowel syndrome (IBS).

METHOD

The present study was a randomized clinical trial with a pre-test and post-test design. Between the winter of 2021 and the end of spring 2022, Taleghani Hospital in Tehran received referrals from the statistical population of IBS patients. Of them, 30 individuals (15 in each group) were chosen by convenience sampling and then randomly allocated to groups. UP (It is emotion-based and intervenes in comorbid symptoms), and ACT treatments were provided to the participants online. The participants in the UP and ACT groups received the desired treatments in eight weekly sessions of 45-60 min.

RESULTS

There was no significant difference between UP pre-test and ACT regarding depression, anxiety, rumination, and life satisfaction (P > 0.05). There was no significant difference between UP and ACT post-test in terms of depression, rumination, and life satisfaction (P > 0.05), but due to anxiety, their difference was significant (P < 0.05). Besides, there was a significant difference between pre-test and post-test phases of UP and ACT regarding depression, anxiety, and rumination (P < 0.05). Still, they had no significant difference regarding life satisfaction (P > 0.05).

CONCLUSION

Therefore, it is suggested that specialists use UP and ACT as effective psychological treatments for the emotional symptoms of IBS patients to improve psychological symptoms.

Involvement of the autonomic nervous system in colonic contractions in conscious Suncus murinus

BACKGROUND

Colonic motility is regulated by various factors along the gut-brain axis; however, detailed mechanisms are unknown. This study aimed to examine the involvement of the autonomic nervous system in colonic motility. Suncus murinus (suncus) is a small laboratory mammal suitable for gastrointestinal motility studies.

METHODS

Colonic motility and concomitant feeding and defecation behaviors in vagotomized and reserpine-administered suncus were recorded simultaneously for 24 h. Furthermore, we performed immunohistochemistry on tyrosine hydroxylase (TH) and in situ hybridization on corticotropin-releasing hormone (CRH) in suncus brain. Additionally, we examined c-Fos expression in the brain using immunohistochemistry in conscious suncus with colorectal distension.

KEY RESULTS

In vagotomized suncus, clustered giant migrating contractions (GMCs), consisting of strong contractions occurring in a short time, were observed, and the percentage of GMCs without defecation increased. The frequency of GMCs in the reserpine-administered suncus increased during a light period (ZT0-4, 4-8) and decreased during a dark period (ZT16-20, 20-24) compared to a vehicle group. Additionally, the percentage of GMCs without defecation in the reserpine-administered suncus increased. Suncus TH-immunopositive neurons were found in the locus coeruleus (LC), as shown in rodents. In contrast, CRH mRNA-expressing cells were not observed in a region assumed to be the Barrington's nucleus (Bar). Furthermore, colorectal distension in conscious suncus induced c-Fos expression in LC TH neurons.

CONCLUSIONS & INFERENCES

Our results suggest that the vagus and sympathetic nerves are not required for induction of GMCs in vivo. However, they are likely to exert a modulatory role in control of GMC frequency in Suncus murinus.

Children and Adolescents with Irritable Bowel Syndrome: Treatment and Management

BACKGROUND

Irritable bowel syndrome (IBS) is a disorder that causes stomach pain in children and adolescents. It may also impact one's quality of life. IBS is linked to gastrointestinal issues such as diarrhoea and constipation. Despite the identification of several potential pathophysiological pathways, the aetiology of IBS remained unknown.

OBJECTIVE

The aim of this paper is to discuss the diagnosis, pathogenesis, case studies and treatment of Irritable bowel syndrome in children and adolescents.

METHODS

This systematic review covered relevant papers from the previous ten years that were accessible in Science Direct, Elsevier, NCBI, and Web of Science related to the pathophysiology and function of pharmacological drugs such as antidepressants, antispasmodics, prokinetics, and antibiotics in children with irritable bowel syndrome.

RESULTS

Only a few prospective therapy techniques have been investigated in children, and even fewer of those have been demonstrated to be effective. This article presents case studies including 50-59 children, which demonstrate a favourable acceptable impact that is more effective than a placebo in terms of reducing symptoms and improving the overall quality of life in children who have irritable bowel syndrome. Furthermore, the majority of the pathophysiological explanations and treatment options discussed are based on adult studies. These major issues arose when treating paediatric IBS, and they must be addressed in order to properly treat children with IBS. Trials that focus on many combinations of pharmacological and non-pharmacological therapies seem to be more helpful.

DISCUSSION

In recent years, a number of systematic reviews have been conducted to evaluate the efficacy of medication treatments in children for IBS; however, the dependability of these systematic reviews needs to be further investigated owing to the various experimental designs and levels of evidence used. This article highlights paediatric therapy options, including pharmaceutical medications such as antidepressants, antispasmodics, prokinetics, and antibiotics. The goal is to alleviate IBS symptoms while also enhancing the quality of life for children with this illness.

Exploring the Nutrition Strategies Employed by Ultra-Endurance Athletes to Alleviate Exercise-Induced Gastrointestinal Symptoms-A Systematic Review

(1) Background: Participation in ultra-endurance sports, particularly ultra-running, has increased over the previous three decades. These are accompanied by high energetic demands, which may be further exacerbated by extreme environmental conditions. Preparation is long-term, comprising of sufficient exercise management, supportive dietary habits, and nutritional intakes for optimal adaptations. Gastrointestinal symptoms are often cited as causing underperformance and incompletion of events. Though the majority do not pose serious long-term health risks, they may still arise. It has been suggested that the nutritional interventions employed by such athletes prior to, during, and after exercise have the potential to alter symptom incidence, severity, and duration. A summary of such interventions does not yet exist, making it difficult for relevant personnel to develop recommendations that simultaneously improve athletic performance by attenuating gastrointestinal symptoms. The aim of this research is to systematically review the literature investigating the effects of a nutrition intervention on ultra-endurance athletes exercise-induced gastrointestinal symptom incidence, severity, or duration. (2) Methods: A systematic review of the literature was conducted (PubMed, CINAHL, Web of Science, and Sports Discus) in January 2023 to investigate the effects of various nutrition interventions on ultra-endurance athletes' (regardless of irritable bowel syndrome diagnosis) exercise-induced gastrointestinal symptoms. Variations of key words such as "ultra-endurance", "gastrointestinal", and "nutrition" were searched. The risk of bias in each paper was assessed using the ADA quality criteria checklist. (3) Results: Of the seven eligible studies, one was a single field-based case study, while the majority employed a crossover intervention design. A total of n = 105 participants (n = 50 male; n = 55 female) were included in this review. Practicing a diet low in short-chain, poorly absorbed carbohydrates, known as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), as well as employing repetitive gut challenges of carbohydrates, remain the most promising of strategies for exercise-induced gastrointestinal symptom management. (4) Conclusion: Avoiding high-FODMAP foods and practicing repetitive gut challenges are promising methods to manage gastrointestinal symptoms. However, sample sizes are often small and lack supportive power calculations.

Dietary monosodium glutamate increases visceral hypersensitivity in a mouse model of visceral pain

BACKGROUND

Monosodium glutamate (MSG) has been identified as a trigger of abdominal pain in irritable bowel syndrome (IBS), but the mechanism is unknown. This study examined whether MSG causes visceral hypersensitivity using a water-avoidance stress (WAS) mouse model of visceral pain.

METHODS

Mice were divided into four groups receiving treatment for 6 days: WAS + MSG gavage, WAS + saline gavage, sham-WAS + MSG gavage, and sham-WAS + saline gavage. The acute effects of intraluminal administration of 10 μM MSG on jejunal extrinsic afferent nerve sensitivity to distension (0-60 mmHg) were examined using ex vivo extracellular recordings. MSG was also applied directly to jejunal afferents from untreated mice. Glutamate concentration was measured in serum, and in the serosal compartment of Ussing chambers following apical administration.

KEY RESULTS

Acute intraluminal MSG application increased distension responses of jejunal afferent nerves from mice exposed to WAS + MSG. This effect was mediated by wide dynamic range and high-threshold units at both physiologic and noxious pressures (10-60 mmHg, p < 0.05). No effect of MSG was observed in the other groups, or when applied directly to the jejunal afferent nerves. Serum glutamate was increased in mice exposed to WAS + MSG compared to sham-WAS + saline, and serosal glutamate increased using WAS tissue (p = 0.0433).

CONCLUSIONS AND INFERENCES

These findings demonstrate that repeated exposure to MSG in mice leads to sensitization of jejunal afferent nerves to acute ex vivo exposure to MSG. This may contribute to visceral hypersensitivity reported in response to MSG in patients with IBS.

Apigenin reduces the suppressive effect of exosomes derived from irritable bowel syndrome patients on the autophagy of human colon epithelial cells by promoting ATG14

BACKGROUND

Inflammatory bowel disease (IBS) is a chronic disorder of the gastrointestinal tract. Exosomes have been involved in various pathological processes including IBS. Apigenin has been reported to suppress inflammatory bowel disease (IBS). However, the regulatory roles of exosomes derived from IBS patients (IBS-exos) on human colon epithelial cells are still unclear.

METHODS

Exosomes were collected from IBS patients (IBS-exos) and co-cultured with CACO-2 cells. Apigenin was used to treat IBS-exos-treated CACO-2 cells. By exploring the public data bank, we figured out the regulators control the autophagy of CACO-2 cells.

RESULTS

Administration of apigenin dose-dependently abolished the inhibitory effect of IBS-exo on the autophagy of CACO-2 cells. A mechanistic study showed that miR-148b-3p bound to 3'UTR to suppress ATG14 and decrease autophagy. Moreover, results suggested that ATG14 overexpression promoted the autophagy of CACO-2 cells in the presence of miR-148b-3p mimic.

CONCLUSION

The current study showed that apigenin dose-dependently abolished the inhibitory effect of IBS-exo on CACO-2 cell autophagy by regulating miR-148b-3p/ATG14 signaling.

Significant Differences in Gut Microbiota Between Irritable Bowel Syndrome with Diarrhea and Healthy Controls in Southwest China

BACKGROUND

Irritable bowel syndrome (IBS) is a heterogeneous disease, which is closely related to environmental factors and gut microbiota.

OBJECTIVE

To study gut microbiota in IBS-D of Han nationality in Southwest China and explore its relationship with environmental factors.

METHODS

One hundred and twenty cases of IBS-D and 63 cases of HCs were recruited; baseline data such as age, height, and weight were collected. HAMA, HAMD, IBS-SSS, IBS-QOL, and laboratory tests were performed. Feces were collected for 16S rDNA sequencing. Then, the differences of gut microbiota were analyzed and looked for biomarkers of each. FAPROTAX was used to predict the functional differences of gut microbiota. Spearman analysis was conducted between the phylum level and environmental factor.

RESULTS

There were significant differences in daily life between IBS-D and HCs, especially in the spicy taste. The scores of HAMA and HAMD, urea, and transaminase in IBS-D were significantly higher than those of HCs. The richness of gut microbiota in IBS-D was significantly lower than that of HCs, as well as the beta diversity, but not diversity. The biomarkers of IBS-D were Prevotella, Clostridiales, and Roseburia, and the biomarkers of HCs were Veillonellaceae, Bacteroides coprocola, and Bifidobacteriales. The functions of gut microbiota in IBS-D were significantly different from HCs. Correlation analysis showed that multiple gut microbiota were closely related to HAMA, IBS-SSS, IBS-QOL, inflammatory indexes, and liver enzymes.

CONCLUSION

There are significant differences in richness of gut microbiota, flora structure, and flora function between IBS-D and HCs in Southwest China. These differences may be closely related to environmental factors such as eating habits, living habits, and mental and psychological factors.

CLINICAL TRIAL REGISTRATION

The trial was registered and approved in China Clinical Trial Registry (Registration No. ChiCTR2100045751).

Obesity Contributes to Inflammation in Patients with IBS via Complement Component 3 and C-Reactive Protein

Irritable Bowel Syndrome (IBS) is usually a lifelong state that disturbs the digestive system. IBS has been linked to low-grade inflammation and the release of inflammatory mediators into the bloodstream. This could be associated with the degree of obesity presented by patients with IBS. Reports imply that IBS is more frequent in obese patients than in the overall population, with a prevalence of up to 31%. Here, we evaluated the serum levels of immunological and inflammation molecules and their correlation with Body Mass Index in IBS patients and the healthy control (HC). Seventy-nine serum samples of the IBS patients and thirty-five of the HC group were analyzed to determine the levels of each molecule and compare them with their BMI. Serum levels of C3 and C4 were significantly increased in IBS patients. C3 and C4 levels were higher in IBS-M and IBS-D subtypes compared with the HC group. When patients were grouped by BMI, a positive correlation between serum C3 (r = 0.49, p < 0.0001) and CRP (r = 0.40, p < 0.001) levels was found. Our results show, for the first time, a correlation between immunological molecules and BMI in IBS patients, suggesting that the inflammatory nature of obesity could contribute to the development of the symptoms in IBS through the stimulation and release of proteins as complement components and CRP.

Oral administration of processed Cassia obtusifolia L. seed powder May reduce body weight and cholesterol in overweight patients with schizophrenia: A 36-week randomized, double-blind, controlled trial of high and low doses

ETHNOPHARMACOLOGICAL RELEVANCE

Obesity in patients with schizophrenia is related to antipsychotic drug use, hypertension, diabetes, and dyslipidemia, which are critical risk factors for cardiovascular disease. Cassia seed is a traditional Chinese medicine that can be used to treat various eye disorders. Anthraquinone-containing Cassia seed were used to lower serum levels of fat and cholesterol.

AIM OF STUDY

The effects of Cassia seed powder on body weight and lipids were investigated in overweight or obese patients with schizophrenia.

METHODS

The present study was designed as a double-blind, randomized, controlled trial. Ninety-four patients with schizophrenia who were overweight or obese were assigned to a control group (CG, 47 patients) and treatment group (TG, 47 patients) that received low dose Cassia seed power (0.3 g once daily) and Cassia seed powder (3.0 g once daily), respectively, for 36 weeks. The main outcome was the change in body mass index and waist circumference (WC). The secondary outcome was the change in serum lipids, C-reactive protein, interleukin-6, and glycated hemoglobin.

RESULTS

Seventy-four patients completed the study (n = 36, CG; n = 38, TG). WC was significantly lower at the second (24 weeks, 98.63 ± 9.44 vs 95.80 ± 10.26 cm, p = 0.023), third (36 weeks, 98.35 ± 9.46 vs 95.05 ± 10.07 cm, p = 0.002), and fourth (48 weeks, 98.78 ± 9.48 vs 93.73 ± 10.28 cm, p < 0.001) follow-ups than at baseline in the TG, but only significantly lower than baseline at the fourth follow-up (100.78 ± 13.98 vs 94.03 ± 9.74 cm, p = 0.006); no significant difference in CG was observed at both the second (101.03 ± 13.62 vs 97.35 ± 8,29 cm, p = 0.08) and third (100.55 ± 13.69 vs 96.55 ± 8.29 cm, p = 0.066) follow-up. The difference in serum total cholesterol and low-density lipoprotein levels between the baseline and the third follow-up was greater in the TG than in the CG (149.68 ± 34.85 vs 179.08 ± 75.87 mg/dL, p = 0.033; 84.40 ± 28.06 vs102.08 ± 34.12 mg/dL, p = 0.015, respectively).

CONCLUSION

In patients with schizophrenia who were overweight or obese, oral administration of Cassia seed powder (3.0 g) for 24 weeks and 36 weeks reduced WC, and oral administration of Cassia seed powder for 36 weeks reduced total cholesterol and low-density lipoprotein levels, suggesting that Cassia seed powder aids the management of patients with schizophrenia who are overweight or obese. However, these results are preliminary, and future studies should use larger sample sizes, multiple testing centers, and multiple dosing.

Effects of Yi-Gan-san on the psychiatric behavior of children and adolescents with Tourette's Syndrome: A randomized, double-blind, controlled preliminary study

ETHNOPHARMACOLOGICAL RELEVANCE

Gilles de la Tourette's Syndrome (TS) is a childhood-onset disease with clinical features of motor and phonic tics. Yi-Gan-san (YGS) is a traditional Chinese medicine formula that can reduce aggressiveness and agitation and inhibit dopamine function. This study investigated the effects of YGS on the psychiatric behavior of children and adolescents with TS.

METHODS

A double-blind, randomized, controlled preliminary study was conducted. A total of 38 patients with TS were assigned to the control group (CG, 19 patients) who received the oral administration of YGS placebo (90% starch and 10% YGS; 2.5 g thrice daily) or to a treatment group (TG, 19 patients) who received YGS for 4 weeks. The primary outcome measure was the change in Yale Global Tic Severity Scale (YGTSS) overall and subscale scores.

RESULTS

The intensity score for phonic tics before oral administration of YGS, and after 2 weeks, 3 weeks and 4 weeks was not significantly different between CG and TG groups (2.94 ± 1.14 vs 2.79 ± 1.08, p = .686; 2.29 ± 1.21 vs 1.95 ± 1.08, p = .370; 2.41 ± 1.18 vs 2.05 ± 1.51, p = .435; and 2.29 ± 1.26 vs 1.84 ± 1.42, p = .323, respectively), while the intensity score for phonic tics after 1-week oral administration of YGS in the TG was 1.89 ± 1.10 lower than 3.06 ± 1.39 in the CG (p = .008).

CONCLUSION

Oral administration of YGS for 1 week only reduced the intensity of phonic tics compared with oral administration of YGS placebo, suggesting that YGS can reduce their intensity for a short period, and the compliance of oral administration of YGS for 4 weeks can be accepted in children and adolescents with Tourette's Syndrome. However, because this study was preliminary, the selection of an appropriate placebo and dosage and long-term observations are crucial areas for future studies.

Buspirone in the management of refractory irritable bowel syndrome: A case report

RATIONALE

Irritable bowel syndrome (IBS) is a chronic and debilitating functional disorder of the gastrointestinal tract manifested by abdominal pain and bowel habit dysregulation. The pathophysiology is complex and management targets symptom resolution. Therapeutic interventions range from dietary modification, psychological interventions, exercise, to the use of antispasmodics, antibiotics, and antidepressants. Anecdotal reports have suggested that buspirone may be beneficial in the treatment of functional dyspepsia and IBS and its physiological effect of reducing gastric tone provides a rational for its benefit.

PATIENT CONCERNS

A 28-year-old man with unremarkable past medical and psychiatric history presented with worsening abdominal pain, bloating, and bowel movement dysregulation of over 6-year duration.

DIAGNOSES

Physical examination revealed mild distension and discomfort on deep palpation. Thorough blood investigations, stool analysis and culture, and imaging were unremarkable except for the detection of mucus with stool. The patient was diagnosed with irritable bowel syndrome with mixed habits.

INTERVENTIONS

Dietary adjustment and a range of medications (mebeverine, simethicone, loperamide, rifaximin, sertraline and amitriptyline) yielded unsatisfactory response of were not tolerated. Buspirone was eventually introduced.

OUTCOMES

Buspirone was associated with a significant and sustained improvement in IBS symptoms and quality of life.

LESSONS

This case suggests that buspirone was effective in treating refractory IBS. Further research is needed to assess the role of buspirone in IBS management.

Investigation the Effectiveness of Duloxetine in Quality of Life and Symptoms of Patients with Irritable Bowel Syndrome

Background:

Selective norepinephrine-serotonin receptor inhibitors (SNRIs) such as duloxetine have already shown beneficial effects on symptoms in irritable bowel syndrome (IBS) patients. The purpose of the present investigation was to assess the efficacy of duloxetine in the symptom and quality of life improvement in diarrhea predominant-IBS (IBS-D) patients.

Materials and Methods:

IN a randomized, double-blind and placebo-controlled study, sixty patients diagnosed with IBS-D (ROM-IV criteria), referred to the gastrointestinal clinic of Rasoul-e-Akram Hospital of Iran university of medical sciences, randomly assigned in the treatment groups, group A: patients who received 135 mg mebeverine tablet twice a day combined with 30 mg duloxetine capsule per day and group B, who received the same regimen, except for placebo capsule once per day instead of duloxetine for twelve weeks. The assessment was performed using the IBS severity index, and IBS quality of life questionnaire (IBS-QOF) at baseline, and weeks 4, 8, and 12 after beginning the treatment. Drug adverse effects and compliance to treatment were evaluated every 2 weeks after starting the treatment.

Results:

Sixty patients completed the trial. The duloxetine group showed significantly greater improvement on the IBS symptoms (P < 0.001), and the IBS-QOF (P < 0.001) in comparison to the placebo group at the endpoint.

Conclusions:

This study showed that adding duloxetine to mebeverine is safe with good efficacy on symptoms and QOL improvement in IBS-D patients. Besides, this study showed that 12 weeks' treatment duration is significantly more effective than 4 weeks' treatment, and drug adverse effects are more prominently seen in the first 2 weeks of treatment.

Uncovering the pathophysiology of irritable bowel syndrome by exploring the gut-brain axis: a narrative review

Objective

To improve the pathophysiological understanding of irritable bowel syndrome (IBS) by exploring the gut-brain axis.

Background

Disorders of gut-brain interaction (DGBIs) are gastrointestinal (GI) disorders in which alterations in bowel functions occur. IBS, which is one of the most studied DGBIs, is linked with abdominal distress or pain without obvious structural or biochemical anomalies.

Methods

The etiology of IBS has not been clearly described but is known to be multifactorial, involving GI motility changes, post-infectious reactivity, visceral hypersensitivity, gut-brain interactions, microbiota dysbiosis, small intestinal bacterial overgrowth, food sensitivity, carbohydrate malabsorption, and intestinal inflammation.

Conclusions

One of the main features of IBS is the occurrence of structural and functional disruptions in the gut-brain axis, which alter reflective and perceptual nervous system reactions. Herein, we provide a brief summary of this topic. Furthermore, we discuss animal models, which are important in the study of IBS, especially as it is linked with stressors. These animal models cannot fully represent the human disease but serve as important tools for understanding this complicated disorder. In the future, technologies, such as organ-on-a-chip models and metabolomics, will provide novel information regarding the pathophysiology of IBS, which will play an important role in treatment development. Finally, we take a brief glance at how acupuncture treatments may hold potential for patients with IBS.

Formulation and evaluation of hydroxypropylmethylcellulose-dicyclomine microsponges for colon targeted drug delivery: In vitro and in vivo evaluation

OBJECTIVE

The objective of present study was to design novel colon targeted delivery of dicyclomine Hydrochloride (DCH) microsponges.

METHODS

Microsponges (MS1-MS4) based on different ratios of hydroxypropylmethylcellulose (HPMC) and DCH was prepared by quasi-emulsion solvent diffusion method. Micro-sponges were analyzed by determining percent yield, encapsulation efficiency, drug content, drug-polymer compatibility and thermal stability. Kinetic analysis of thermal stability data was done by Chang method, Friedman method and Broido method. In vitro dissolution study was carried out at pH 1.2, pH 6.8 and pH 7.4 at different time intervals.

RESULTS

Results showed that there was no chemical interaction between DCH and HPMC in all microsponge formulations. Production yield, drug content and encapsulation efficiency were enhanced on increasing the drug-polymer ratio. Thermal stability of all the micro-sponges was greater than that of pure drug. In vitro drug release was decreased on increasing the polymer concentration at different pH levels. The newly prepared micro-sponges based on HPMC were confirmed as a promising means of colon targeted delivery of DCH. An HPLC method was developed and validated for the bioequivalence study of newly designed microsponges. Pharmacokinetics parameters were calculated using linear trapezoidal method after single oral administration of microsponges in white albino rabbits. Pharmacokinetics results indicate an enhancement in the value of t1/2, tmax, Cmax and AUC0-t of DCH in the microsponges as compared to standard DCH showing enhanced bioavailability of drug after microsponges formation.

CONCLUSION

The current study shows a new approach for colon specific delivery of DCH based on microsponges.

(Poly)phenols in Inflammatory Bowel Disease and Irritable Bowel Syndrome: A Review

(Poly)phenols (PPs) may have a therapeutic benefit in gastrointestinal (GI) disorders, such as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD). The aim of this review is to summarise the evidence-base in this regard. Observational evidence does not give a clear indication that PP intake has a preventative role for IBD or IBS, while interventional studies suggest these compounds may confer symptomatic and health-related quality of life improvements in known patients. There are inconsistent results for effects on markers of inflammation, but there are promising reports of endoscopic improvement. Work on the effects of PPs on intestinal permeability and oxidative stress is limited and therefore conclusions cannot be formed. Future work on the use of PPs in IBD and IBS will strengthen the understanding of clinical and mechanistic effects.

A randomized, double-blind, placebo-controlled study to assess efficacy of mirtazapine for the treatment of diarrhea predominant irritable bowel syndrome

Background

Ample evidence indicates the efficacy of serotonin type 3 (5-HT₃) receptor antagonists in the treatment of patients with diarrhea-predominant irritable bowel syndrome (IBS-D). Mirtazapine is an atypical antidepressant with a well-known 5-HT₃ receptor antagonist property. This study, therefore, was undertaken to investigate whether compared to placebo, mirtazapine would be efficacious and safe in the treatment of patients with IBS-D.

Methods

From November 2019 until July 2020, 67 patients meeting Rome IV criteria for IBS-D were randomized in a double-blind fashion into either the mirtazapine treatment group (n = 34) or the placebo treatment group (n = 33). Patients started with mirtazapine 15 mg/day at bedtime for one-week; after which the dose was increased to 30 mg/day for an additional 7-week. Outcomes included changes in the total IBS symptom severity score (IBS-SSS), Hospital anxiety and depression scale score (HADS), and IBS Quality of Life. Additionally, changes in the diary-based symptoms scores including pain, urgency of defecation, bloating, stool frequency, and stool consistency based on the 7-point Bristol Stool Form Scale (BSFS), and a number of days per week with pain, urgency, diarrhea, or bloating, once during the 1-week run-in period, and once during the last week of treatment were recorded.

Results

All analyses were performed on an Intention-to-Treat (ITT) analysis data set. The results showed compared to placebo, mirtazapine is more efficacious in decreasing the severity of IBS symptoms (P-value = 0.002). Further, at the end of the treatment period, all diary-derived symptoms except bloating showed significantly more improvement in the mirtazapine-treated subjects compared to the placebo-treated subjects. While was well-tolerated, mirtazapine also significantly improved the patients’ quality of life (P-value = 0.04) and anxiety symptoms (P-value = 0.005).

Conclusions

Overall, mirtazapine seems to have a potential benefit in the treatment of patients with IBS-D, particularly those with concomitant psychological symptoms. However, further studies are warranted to determine whether these findings are replicated.

Trial registration

Trial registration: Registration number at Iranian Registry of Clinical Trials: IRCT20120215009014N311. Registration date: 2019-10-21.

Prevalence of Irritable Bowel Syndrome and Frequency of Symptoms in the General Population of Pakistan

INTRODUCTION

Irritable bowel syndrome (IBS) is a chronic and debilitating functional gastrointestinal disorder. Risk factors include infective enteritis, female sex, antibiotic exposure, anxiety, and depression. The aim of this study is to find out the prevalence of IBS in healthy population and determine the characteristics of symptoms.

MATERIAL AND METHODS

A cross-section study was conducted in the internal medicine unit of a tertiary care hospital in multiple cities of Pakistan. Eight hundred (800) healthy peoples were selected for study from June 2019 to August 2019. Diagnosis of IBS was made by using Rome III criteria.

RESULTS

The prevalence of irritable bowel syndrome (IBS) in general population in our study was 33.2%. IBS was more common in females compared to males (57.7% vs. 42.2%; p value = 0.009). IBS was more common in age group between 20 and 29 years (45.5%). Among patient diagnosed with IBS in this study, the most common was bloating (74.7%) followed by increased stool frequency (54.4%).

CONCLUSION

IBS is very prevalent in Pakistan, yet there is very little data and awareness related to it. Any change in stool frequency or consistency in young adults, especially women, shall be evaluated for IBS after ruling out other diseases. Early diagnosis and treatment of IBS will assist in improving the patient's quality of life.

Gluten Free Diet for the Management of Non Celiac Diseases: The Two Sides of the Coin

A lifelong adherence to a gluten-free (GF) diet is currently the only treatment for Celiac disease (CD), an autoimmune disorder that arises after gluten ingestion in individuals who are genetically predisposed. The gluten intake exerts toxic effects through several pathways involving gut barrier integrity, intestinal microbiota composition and immune system stimulation. However, despite the great benefit of GF diet for CD patients, its use has been debated. Indeed, individuals who adopt this diet regime may be at risk of nutrient deficiencies. Emerging evidence supports a beneficial effect of a GF diet also for other pathological conditions, including gluten-related disorders (GRD) often associated to CD, such as Non celiac gluten sensitivity (NCGS) and Dermatitis Herpetiforme (DH) as well as Irritable bowel syndrome (IBS) and Diabetes. This suggests a pathogenic role of gluten in these conditions. Despite the growing popularity of GF diet among consumers, to date, there are limited evidences supporting its use for the management of non-celiac diseases. Therefore, in this review, we discuss whether the GF diet could really improve the general quality of life of patients with GRD and non-GRD conditions, keeping in mind its sensorial limitations and nutritional inadequacies. In addition, we discuss the current motivations, leading to the use of a GF diet, despite the inferior quality of GF products respect to those containing gluten.

Multiple Pathway-Mediated Gut-Modulatory Effects of Maerua subcordata (Gilg) DeWolf

BACKGROUND

Gastrointestinal disorders are often poorly managed, especially in developing countries, where there are limited resources and therapeutic options. Despite the rich diversity of medicinal plants that offer effective treatment options with fewer side effects, studies that provide scientific verification are lacking. Maerua subcordata (Gilg) DeWolf is among the plants claimed to have wide traditional medicine, use, including as a remedy against gastrointestinal problems. Therefore, this work aimed to evaluate the gut-modulatory effects of a crude leaf extract of M. subcordata (MSL.Cr), as well as its possible mechanism of action.

METHODS

A castor oil (10 mL/kg)-induced diarrheal mouse model was used to evaluate the antidiarrheal effect of MSL.Cr, and the spasmodic/antispasmodic effect of the extract was assessed using isolated rabbit jejunum with and without addition of standard cholinergic agonists/antagonists to predict the possible mechanism of action.

RESULTS

MSL.Cr exhibited 40% and 80% protection against castor oil-induced diarrhea in mice at doses of 500 and 1,000 mg/kg, respectively. In isolated rabbit jejunum, the extract increased spontaneous contractions at low doses (0.01-0.1 mg/mL), and was sensitive to atropine, whereas it showed complete inhibition at higher doses (0.3-1 mg/mL). It was shown that the relaxant effect was possibly mediated by the involvement of phosphodiesterase-enzyme inhibition and K+-channel activation. The extract potentiated the control concentration-response curve of carbachol, shifting it to the left, similarly to the control drug papaverine. The potassium-channel opening-like activity of MSL.Cr was possibly mediated by the involvement of aspecific K+-channels inhibition, since tetraethylammonium, anunselective antagonist of K+ channels, significantly reversed its inhibitory effect.

CONCLUSION

This study showed that the M. subcordata leaf extract demonstrated gut-modulatory effects, possibly mediated by a combination of muscarinic-receptor stimulation, phosphodiesterase inhibition, and aspecific K+-channel activation.

Improved gastrointestinal health for irritable bowel syndrome with metagenome-guided interventions

Irritable bowel syndrome (IBS) is the most prevalent functional gastrointestinal disorder worldwide, and the most common reason for referral to gastroenterology clinics. However, the pathophysiology is still not fully understood and consequently current management guidelines are very symptom-specific, leading to mixed results. Here we present a study of 88 individuals with IBS who had baseline sequencing of their gut microbiome (stool samples), received targeted interventions that included dietary, supplement, prebiotic/probiotic, and lifestyle recommendations for a 30-day period, and a follow-up sequencing of their gut microbiome. The study's objectives were to demonstrate unique metagenomic signatures across the IBS phenotypes and to validate whether metagenomic-guided interventions could lead to improvement of symptom scores in individuals with IBS. Enrolled subjects also completed a baseline and post-intervention questionnaire that assessed their symptom scores. The average symptom score of an individual with IBS at baseline was 160 and at the endpoint of the study the average symptom score of the cohort was 100.9. The mixed IBS subtype showed the most significant reduction in symptom scores across the different subtypes (average decrease by 102 points, P = 0.005). The metagenomics analysis reveals shifts in the microbiome post-intervention that have been cross-validated with the literature as being associated with improvement of IBS symptoms. Given the complex nature of IBS, further studies with larger sample sizes, more targeted analyses, and a broader population cohort are needed to explore these results further.

Efficacy of Lactobacillus paracasei HA-196 and Bifidobacterium longum R0175 in Alleviating Symptoms of Irritable Bowel Syndrome (IBS): A Randomized, Placebo-Controlled Study

Specific probiotic strains can alleviate the gastrointestinal (GI) symptoms and psychiatric comorbidities of irritable bowel syndrome (IBS). In this randomized, double-blind, placebo-controlled study, the efficacy of Lactobacillus paracasei HA-196 (L. paracasei) and Bifidobacterium longum R0175 (B. longum) in reducing the GI and psychological symptoms of IBS was evaluated in 251 adults with either constipation (IBS-C), diarrhea (IBS-D), or mixed-pattern (IBS-M). Following a 2-week run-in period, participants were randomized to one of three interventions: L. paracasei (n = 84), B. longum (n = 83) or placebo (n = 81). IBS symptoms, stool frequency and consistency and quality of life were assessed by questionnaires. The differences from baseline in the severity of IBS symptoms at 4 and 8 weeks were similar between groups. Participants in this study were classified, after randomization, into subtypes according to Rome III. Within the L. paracasei group, complete spontaneous and spontaneous bowel movement frequency increased in participants with IBS-C (n = 10) after 8 weeks of supplementation (both p < 0.05) and decreased in participants with IBS-D (n = 10, p = 0.013). Both L. paracasei and B. longum supplementation improved the quality of life in emotional well-being and social functioning compared with baseline (all p < 0.05). In conclusion, L. paracasei and B. longum may reduce GI symptom severity and improve the psychological well-being of individuals with certain IBS subtypes.

Treating irritable bowel syndrome through an interdisciplinary approach

Irritable bowel syndrome (IBS) is a functional disorder with a multifactorial etiology and a complex clinical picture. The recent discovery of the dysregulation of the gut-brain axis as an important pathogenetic mechanism for the development of IBS is a kind of breakthrough in the understanding of IBS and prevalent comorbidities. Nevertheless, IBS treatment still causes many problems and often turns out to be ineffective or brings only short-term effects in reducing symptom severity. In reference to the characteristics of IBS, including new findings regarding etiopathogenesis, an interdisciplinary treatment approach is proposed and the roles of medical and psychological interventions are underlined. The literature search was conducted using electronic databases with a focus on the latest publications. The review may be useful for matching the best strategy of IBS management.

All that a physician should know about FODMAPs

A diet low in poorly absorbed, fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is now considered as an effective strategy for symptoms control in patients with irritable bowel syndrome (IBS). The low FODMAP diet is administered in three phases, namely restriction of all dietary FODMAPs followed by rechallenge and then reintroduction of specific FODMAPs according to the tolerance of patients. A dietician should be involved in patients in whom a low FODMAP diet is planned. While restricting high FODMAPs, it is pertinent that patients are advised a well-balanced diet and suitable alternatives with low FODMAP contents in each food groups are prescribed. Strict adherence to a low FODMAP diet has been shown to improve symptoms, stool output, quality of life, and the overall well-being of patients with IBS. For those who do not respond to this dietary approach, a normal diet may be initiated and other treatment strategies (dietary or nondietary) should be considered. Interestingly, the low FODMAP diet has also been tried in other functional disorders, nonceliac gluten sensitivity, and even inflammatory bowel disease. Since the concept of FODMAP is relatively new, there is only limited data on the content of FODMAP in the Indian food items and there is a need to address this question. There is also a need for well-designed and adequately powered studies to explore the efficacy of low FODMAP diet in patients with IBS. In the present review article, we have compiled all the relevant information about FODMAPs with an objective to provide comprehensive information on FODMAPs to a physician.

Evaluation of the effect of 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol in comparison with metronidazole in an in vitro culture of Blastocystis in samples of patients with irritable bowel syndrome

Metronidazole is the most-used pharmaceutical for the treatment of infection by Blastocystis. However, studies have reported resistance of the microorganism towards this pharmaceutical. In Mexico, studies concerning the prevalence of this parasite and its relationship to Irritable Bowel Syndrome have been carried out. To evaluate the in vitro effect of metronidazole and the compound 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol over Blastocystis, as well as the prevalence of Blastocystis in patients with Irritable Bowel Syndrome. A prospective, transversal design study (April 2016-April 2017) of 51 samples of patients with Irritable Bowel Syndrome, obtained from the ISSEMyM Medical Center in Toluca, Mexico. For the identification of Blastocystis was done in three serial stool samples through direct microscopic examination and the Ritchie technique. The in vitro susceptibility test towards metronidazole and the triazolic compound was done through a microculture in concentrations of 1 to 1000 µg/mL, each one in triplicate. A 31.3% prevalence of Blastocystis was observed in the population, with greater prevalence in women (30.2%) than in men (25%). In the susceptibility test, a CL50 of 64 µg/mL was obtained for metronidazole, in comparison to the CL50 of 250 µg/mL for 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol. This molecule in development has an effect for the treatment of infection by Blastocystis in vitro in patients with IBS and therefore, more studies should be performed.

Randomized clinical trial: the effect of probiotic Bacillus coagulans Unique IS2 vs. placebo on the symptoms management of irritable bowel syndrome in adults

The therapeutic effects of B. coagulans Unique IS2 have been well established in children with irritable bowel syndrome (IBS), but its efficacy in adults remain under reported. Thus, in this study the efficacy of B. coagulans Unique IS2 in the management of IBS symptoms in adults was investigated. Patients (n = 153) fulfilling Rome III criteria were provided placebo capsules for a 2 weeks run-in period. Only patients satisfying compliance criteria (n = 136) were randomized (double blind) to receive either B. coagulans Unique IS2 (2 billion CFU) or placebo capsules daily for 8 weeks. Reduction of abdominal discomfort/pain intensity and increase in complete spontaneous bowel movements were analyzed as primary end points. Other clinical symptoms of IBS and serum cytokines were also evaluated. B. coagulans Unique IS2 showed significant improvement in primary and secondary endpoints, as compared to placebo. Haematology of both the arms remained normal. No significant changes in pro- (IL-6, IL-12, TNF-α, INF- γ) and anti-inflammatory cytokine (IL-10) levels were detected at the end of B. coagulans treatment (8 weeks) as compared to placebo. B. coagulans was well tolerated with no severe adverse events to report. Overall, the results demonstrate that B. coagulans Unique IS2 is efficacious in the management of IBS symptoms in adults (18–60 years).

Effects of probiotic supplementation on post-infectious irritable bowel syndrome in rodent model

BACKGROUND

Probiotics have been reported to be the active component used in the treatment of many functional gastrointestinal symptoms and syndromes. Lactobacillus and yeast culture are extensively used in probiotic supplements and traditional treatments for irritable bowel syndrome (IBS). The aim of this study was to investigate the effects of probiotic treatments (Lactobacillus acidophilus LA5, Bifidobacterium animalis subsp. lactis BB12 and Saccharomyces cerevisiae var. boulardii) on the behavioral response, targeted gene expression and pro-inflammatory cytokine levels of Pi (Post infectious)-IBS -induced mice.

METHODS

Pathogen-free male C57L/B6 mice and the Trichinella-infected mice were used to measure the score of abdominal withdrawal reflex (AWR). To compare molecular, biological and biochemical evidences of given probiotics with normal and positive control groups in mice, we conducted quantitative reverse transcription polymerase chain reaction (RT-qPCR), western blotting, and cytokine analysis.

RESULTS

Pi-IBS-induced immune response was confirmed that PAR-2 mRNA level was significantly increased by Trichinella infection (P < 0.05). The reduction of Pi-IBS symptoms through Trichinella infection and the effects of given probiotics were confirmed by a change in the protein levels of cytokines (P < 0.05). In addition, the administration of DW (Daewon) probiotics significantly decreased serum levels of IL-1 and IL-6 (P < 0.05).

CONCLUSIONS

We have demonstrated that the given probiotics decreased pro-inflammatory cytokine levels in both the control and Pi-IBS induced mice. Taken all the results together, the results support that DW probiotics has a potential as a probiotic medication for patient with IBS via regulating TNF-α and IL-6 protein levels and serum IL-1 and IL-6 levels.

The effect of Xiang-Sha-Liu-Jun-Zi tang (XSLJZT) on irritable bowel syndrome: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Irritable bowel syndrome (IBS) is characterized by chronic, recurrent abdominal pain or abdominal discomfort and changes in defecation habits. Xiang-Sha-Liu-Jun-Zi tang (XSLJZT) is a traditional Chinese medical formula that can modulate gastrointestinal disturbance.

PURPOSE

To investigate the therapeutic effect of XSLJZT on IBS.

MATERIALS AND METHODS

This study was designed as a double-blind, randomized, controlled preliminary study. Eighty patients with IBS were assigned to a control group (CG, 40 patients) that received oral administration of an XSLJZT 10% comparator (3.0 g three times daily) for 28 days or to a treatment group (TG, 40 patients) that received XSLJZT. The primary outcome measure was changes in scores on the Gastrointestinal System Rating Scale-IBS. The secondary outcome measures were changes in scores on the irritable bowel syndrome-quality of life (IBS-QOL) and World Health Organization-quality of life-brief.

RESULTS

A total of 63 patients completed the study (n = 31 for the CG; n = 32 for the TG). The TG were discovered to have significantly lower diarrhea scores than the CG at V2 (second assessment) compared with V1 (first assessment, baseline) (mean change ± SD: CG: 0.19 ± 1.33 vs. TG: -0.38 ± 0.91, p = 0.05). The scores for Item 28 on the IBS-quality of life (QOL) scale ("I feel frustrated that I cannot eat when I want because of my bowel problems") were lower in the CG at V3 (third assessment) compared with V1 but slightly higher in the TG (CG: -0.48 ± 0.89 vs. TG: 0.03 ± 0.65, p = 0.01).

CONCLUSION

Oral administration of XSLJZT (3.0 g) for 28 days lowered the mean diarrhea score in patients with IBS, indicating that the patients in the TG had greater diarrhea improvement than those in the CG. The present study used 10% XSLJZT as a comparator, and the different items of the Gastrointestinal System Rating Scale-IBS, IBS-QOL, and World Health Organization Quality of Life-Brief were scored separately. Therefore, the selection of an appropriate comparator or placebo and score assessment are crucial issues for future study.

Update on Pharmacotherapy for Irritable Bowel Syndrome

PURPOSE OF REVIEW

Irritable bowel syndrome (IBS) is a functional GI disorder that affects a large percentage of the population and presents a significant socio-economic burden on the society. In this article, we reviewed the evidence supporting various pharmacological treatment options for IBS.

RECENT FINDINGS

Rifaximin, eluxadoline, and alosetron have demonstrated that they reduce symptom severity improving quality of life in patients with IBS-diarrhea. Ramosetron is a promising agent in development. Peppermint oil has also demonstrated a positive impact on some symptoms of IBS. For IBS with constipation, traditional laxatives have failed to demonstrate significant benefit. However, lubiprostone, linaclotide, and plecanatide have demonstrated improvement of IBS with constipation in large, placebo-controlled trials. Tenapanor, a sodium/hydrogen exchanger 3 inhibitor, appears to be a promising treatment option in the pipeline. There are multiple pharmacologic agents with a variety of mechanisms that have demonstrated efficacy in IBS with diarrhea and constipation. There are no established pharmacologic agents for IBS with a mixed bowel pattern. There is a promising pipeline for additional novel therapies for IBS.

Influence of Dietary Restriction on Irritable Bowel Syndrome

Up to two-thirds of patients with IBS attribute their gastrointestinal symptoms to food. The therapeutic focus of IBS has been to alleviate gastrointestinal symptoms, approached by pharmaceutical and non-pharmaceutical treatments. Although the most traditional approach has involved the use of medications such as bulking agents, anticholinergics, antispasmodics, and antidiarrheals, unfortunately these are only modestly effective and patients are left with a small menu of successful pharmacologic agents. These treatments, however, are not always enough to alleviate symptoms. Alternative approaches have therefore been tried, including dietary manipulation. This article aims to review dietary restrictions as a non-pharmaceutical management approach for IBS, covering literature on various dietary triggers and the impact of dietary manipulation on gastrointestinal symptoms.

Review of the role of abdominal imaging in irritable bowel syndrome

The role of radiologic imaging in the investigation of irritable bowel syndrome (IBS) remains a subject of debate and there is some evidence, from recent studies of utilization of imaging in IBS, which focused on associated costs and radiation exposure, that imaging is being used relatively widely in these patients. This review aims to assess current best evidence to accurately define the role of radiologic imaging in IBS patients. Primary and secondary literature searches were performed. Evidence suggests that the lack of "red flag" or alarm features in IBS patients should reassure the clinician that the diagnosis of IBS is correct and United States and United Kingdom guidelines recommend no radiologic imaging for IBS patients if alarm features are not present. In patients presenting with IBS symptoms and alarm features, radiologic testing may be used to exclude an alternative diagnosis and the imaging modality should be chosen based on the most likely alternative diagnosis.

The possible role of bacteria, viruses, and parasites in initiation and exacerbation of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a prolonged and disabling functional gastrointestinal disorder with the incidence rate of 18% in the world. IBS could seriously affect lifetime of patients and cause high economic burden on the community. The pathophysiology of the IBS is hardly understood, whereas several possible mechanisms, such as visceral hypersensitivity, irregular gut motility, abnormal brain-gut relations, and the role of infectious agents, are implicated in initiation and development of this syndrome. Different studies demonstrated an alteration in B-lymphocytes, mast cells (MC), T-lymphocytes, and cytokine concentrations in intestinal mucosa or systemic circulation that are likely to contribute to the formation of the IBS. Therefore, IBS could be developed in those with genetic predisposition. Infections' role in initiation and exacerbation of IBS has been investigated by quite several clinical studies; moreover, the possible role of some pathogens in development and exacerbation of this disease has been described. It appears that the main obligatory pathogens correspond with the IBS disease, Clostridium difficile, Escherichia coli, Mycobacterium avium subspecies paratuberculosis, Campylobacter concisus, Campylobacter jejuni, Chlamydia trachomatis, Helicobacter pylori, Pseudomonas aeruginosa, Salmonella spp, Shigella spp, and viruses, particularly noroviruses. A number of pathogenic parasites (Blastocystis, Dientamoeba fragilis, and Giardia lamblia) may also be involved in the progression and exacerbation of the disease. Based on the current knowledge, the current study concludes that the most common bacterial, viral, and parasitic pathogens may be involved in the development and progression of IBS.

Irritable bowel syndrome: the clinical approach

Irritable bowel syndrome (IBS) is a chronic and debilitating functional gastrointestinal disorder which presents with abdominal pain associated with alteration of bowel habits. IBS is a common condition affecting 9-23% of the general population, being the 80% female, with considerable impact on quality of life and health care costs. The exact pathogenesis of IBS remains elusive, but is clearly multifactorial and includes environmental and host factors. Management of patients with IBS is challenging since diagnosis and treatment could require several approaches with unsatisfactory results. In any case, the diagnosis of IBS is based on the positive identification of symptoms consistent with this condition and by excluding an underling organic disease. Before choosing therapeutic options, a strong reassuring physician-patient relationship is crucial. The therapeutic approach of IBS may consist of both non-pharmacological therapies and pharmacotherapy and should be based on prevalent symptomatology. Lifestyle modifications such as stress reduction and increased physical activity seem to be useful to improve symptoms and should be encouraged. The same for dietary modifications that represent an important first-line therapeutic option. The pharmacological treatment should take into account the predominant symptom and test one drug at a time with a predefined time point for effectiveness evaluation and dosage adjustment. This clinical review offers an updated overview on epidemiology, pathogenesis, diagnosis and treatment of IBS.

Depressive symptoms in patients with irritable bowel syndrome: a meta-analysis of comparative studies

Depression is common in patients with irritable bowel syndrome (IBS), but the reported prevalence across different studies is inconsistent. This meta-analysis systematically examined the presence and severity of depressive symptoms in patients with IBS. Two investigators independently performed a literature search. The pooled depressive symptom severity was calculated using a random effects model. Subgroup, sensitivity and meta-regression analyses were conducted to examine the moderating factors of the development of depressive symptoms. Twenty four studies (n=2,837) comparing depressive symptoms between IBS patients (n=1,775) and healthy controls (n=1,062) were identified; 14 (58.3%) studies were rated as high quality. Compared to healthy controls, IBS patients had more frequent (OR=9.21, 95%CI: 4.56-18.57, P<0.001; I2=76%) and more severe depressive symptoms (n=1,480, SMD=2.02, 95%CI: 1.56-2.48, P<0.001; I2=94%). Subgroup analyses revealed that patients with all IBS subtypes had more severe depressive symptoms than controls. In addition, versions of the Hamilton Depression Rating Scale (HAM-D) and IBS diagnostic criteria were significantly associated with depressive symptom severity. Meta-regression analyses revealed that female gender, younger age and small sample size were significantly associated with more severe depressive symptoms. In conclusion, meta-analytic data showed that IBS patients had more frequent and severe depressive symptoms than healthy controls. Adequate screening and treatment for depression should be developed and implemented in this patient population.

A Comprehensive Look at Irritable Bowel Syndrome and its Associated Factors Considering the Rome IV Criteria: A Penalized Smoothly Clipped Absolute Deviation Regression Approach in the Pars Cohort Study

BACKGROUND

After the introduction of the Rome IV criteria for the diagnosis of irritable bowel syndrome (IBS), studies on the clinical significance of the new criteria in the settings of a large study has been scarce.

Objective: Herein we used the infrastructures provided by one the largest cohort studies in Iran to evaluate the epidemiological features related to IBS.

METHODS

A total of 9264 participants, were enrolled in the initial registry. Diagnosis of IBS was done using the Rome IV criteria. Individuals with IBS were compared with a control group. Since the study included a large sample size of patients, we used the penalized smoothly clipped absolute deviation (SCAD) regression analysis to construct a model for the evaluation of factors associated with IBS.

RESULTS

Overall, data of 9163 participants entered the final analysis. In total, 1067 (11.6%) individuals were diagnosed with IBS, among which 57 (5.3%) were diarrhea dominant (IBS-D), 380 (35.6%) were constipation dominant (IBS-C), and 630 (59%) did not mention having any of the two (IBS-U). In the regression model, back pain/arthralgia (OR: 1.98, 95% CI: 1.65 - 2.40), insomnia (OR: 1.65, 95% CI: 1.40 - 1.93), depression (OR: 1.64, 95% CI: 1.38 - 1.95), female sex (OR: 1.58, 95% CI: 1.27 - 1.96), anxiety (OR: 1.43, 95% CI: 1.21 - 1.69), and being married (OR: 1.23, 95% CI: 1.03 - 1.48), were associated with higher rates of IBS. We found that IBS prevalence displays a peak at the age of 41 years for both men and women.

CONCLUSION

The present study provides a background for follow-up studies to be conducted in order to evaluate causality between IBS and some major diseases such as liver disease. We also found that opium use, although not statistically significant, in addition to sex, education, back/joint pain, depression, insomnia, anxiety, and marital status might be a contributing factor in IBS.

Gene Expression Profiling and Assessment of Vitamin D and Serotonin Pathway Variations in Patients With Irritable Bowel Syndrome

BACKGROUND/AIMS

Irritable bowel syndrome (IBS) is a multifaceted disorder that afflicts millions of individuals worldwide. IBS is currently diagnosed based on the presence/duration of symptoms and systematic exclusion of other conditions. A more direct manner to identify IBS is needed to reduce healthcare costs and the time required for accurate diagnosis. The overarching objective of this work is to identify gene expression-based biological signatures and biomarkers of IBS.

METHODS

Gene transcripts from 24 tissue biopsy samples were hybridized to microarrays for gene expression profiling. A combination of multiple statistical analyses was utilized to narrow the raw microarray data to the top 200 differentially expressed genes between IBS versus control subjects. In addition, quantitative polymerase chain reaction was employed for validation of the DNA microarray data. Gene ontology/pathway enrichment analysis was performed to investigate gene expression patterns in biochemical pathways. Finally, since vitamin D has been shown to modulate serotonin production in some models, the relationship between serum vitamin D and IBS was investigated via 25-hydroxyvitamin D (25[OH]D) chemiluminescence immunoassay.

RESULTS

A total of 858 genetic features were identified with differential expression levels between IBS and asymptomatic populations. Gene ontology enrichment analysis revealed the serotonergic pathway as most prevalent among the differentially expressed genes. Further analysis via real-time polymerase chain reaction suggested that IBS patient-derived RNA exhibited lower levels of tryptophan hydroxylase-1 expression, the enzyme that catalyzes the rate-limiting step in serotonin biosynthesis. Finally, mean values for 25(OH)D were lower in IBS patients relative to non-IBS controls.

CONCLUSIONS

Values for serum 25(OH)D concentrations exhibited a trend towards lower vitamin D levels within the IBS cohort. In addition, the expression of select IBS genetic biomarkers, including tryptophan hydroxylase 1, was modulated by vitamin D. Strikingly, the direction of gene regulation elicited by vitamin D in colonic cells is "opposite" to the gene expression profile observed in IBS patients, suggesting that vitamin D may help "reverse" the pathological direction of biomarker gene expression in IBS. Thus, our results intimate that IBS pathogenesis and pathophysiology may involve dysregulated serotonin production and/or vitamin D insufficiency.

Modulation of inflammation by toll-like receptor 4/nuclear factor-kappa B in diarrhea-predominant irritable bowel syndrome

In order to investigate the function of toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-κB) signal pathways in the pathogenesis of diarrhea-predominant irritable bowel syndrome (IBS-D), IBS-D animal models were established in wistar rats challenged with acute and chronic stresses (29 days). Wistar rats without stress-challenged were used as controls. IBS-D models were randomly divided into two groups: one was treated with normal saline, another group was treated with TLR4/NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC) (50mg/kg/week) for continuous four times. Our results demonstrate that continuous stresses can induce the characteristic symptoms of IBS-D, including high wet stool rate and intestinal flora imbalance. Further examinations of colon tissues show that the protein expression levels of TLR4 and NF-κB in IBS-D groups are higher than that in control group. The secretory levels of interleukin (IL-8), tumor necrosis factor α (TNFα), and myeloid differentiation factor 88 (MyD88) are significantly increased in IBS-D group. Administration with PDTC effectively downregulates levels of these inflammatory factors. In contrast, interleukin-10 (IL-10) is in an opposite alteration with lower levels in IBS-D groups and the PDTC treatment increases it to the levels as in control group. Moreover, inhibition of the TLR4/NF-κB by PDTC improves the microstructure of intestinal mucosa mainly by increasing the height of villi. Our results suggest that TLR4/NF-κB signal pathway plays an important role in the modulation of inflammatory responses in IBS-D, which might be a therapeutic target for the IBS-D. All of these findings also provide the evidence concerning an inherent linkage between the axis of stress/NF-κB/inflammation and IBS-D.

Impacts of Daily Habits, Health Status, and Health Promoting Behavior on Prevalence of Irritable Bowel Syndrome among Female Adolescents

PURPOSE

This study was to investigate impacts of daily habits, health status and health promoting behavior on prevalence of irritable bowel syndrome (IBS) among female high school students.

METHODS

The survey was conducted from 526 female students in high school. Rome III criteria was used to diagnose IBS. Data of daily habits, health status, and health promoting behavior were collected through self-administered structured questionnaires.

RESULTS

The prevalence of IBS was 25.7%. Compared to the non-IBS, the IBS group scored significantly lower in exercise time, sleeping time, four dimensions of health status (physical, emotional, social, spiritual health) and management of relationship and stress in health promoting behavior. Risk factors influencing IBS were exercise time, physical health and emotional health status.

CONCLUSION

The results of this study suggest that nursing interventions and education programs are important to be developed, while considering exercise, health status and health promoting behaviors for female adolescents in order to manage their IBS.

Novel treatment strategies for smooth muscle disorders: Targeting Kv7 potassium channels

Smooth muscle cells provide crucial contractile functions in visceral, vascular, and lung tissues. The contractile state of smooth muscle is largely determined by their electrical excitability, which is in turn influenced by the activity of potassium channels. The activity of potassium channels sustains smooth muscle cell membrane hyperpolarization, reducing cellular excitability and thereby promoting smooth muscle relaxation. Research over the past decade has indicated an important role for Kv7 (KCNQ) voltage-gated potassium channels in the regulation of the excitability of smooth muscle cells. Expression of multiple Kv7 channel subtypes has been demonstrated in smooth muscle cells from viscera (gastrointestinal, bladder, myometrial), from the systemic and pulmonary vasculature, and from the airways of the lung, from multiple species, including humans. A number of clinically used drugs, some of which were developed to target Kv7 channels in other tissues, have been found to exert robust effects on smooth muscle Kv7 channels. Functional studies have indicated that Kv7 channel activators and inhibitors have the ability to relax and contact smooth muscle preparations, respectively, suggesting a wide range of novel applications for the pharmacological tool set. This review summarizes recent findings regarding the physiological functions of Kv7 channels in smooth muscle, and highlights potential therapeutic applications based on pharmacological targeting of smooth muscle Kv7 channels throughout the body.

MicroRNA-199b expression level and coliform count in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common intestinal disorder. The pathophysiology of IBS may involve an altered intestinal microbiota. Recent studies have shown that alterations in microRNA (miRNA) levels have affected IBS and its subtypes. We aimed to compare both the count of Coliform and serum level of miRNA-199b between patients with IBS and healthy controls and to find the relationship between the Coliform and miRNAs in patients with IBS. Patients with IBS were classified into three subgroups based on their predominant bowel pattern as defined by Rome III criteria. Quantitative culture of Coliform and determination of serum miRNA-199b expression level by quantitative real-time PCR in IBS group versus healthy controls were performed. There was a significant increase in the count of Coliform in patients with IBS and its different subtypes when compared with healthy controls. There was a significant decrease of serum miR-199b expression level in patients with IBS and its different subtypes when compared with healthy controls with the highest level (1.9 ± 0.53 log scale) in healthy controls and lowest one (0.71 ± 0.27 log scale) in IBS with diarrhea (IBS-D) subtype. Moreover, there was a negative correlation between the count of Coliform and the serum miRNA-199b expression level in IBS. This study reported that there was a significant increase in the count of Coliform and a decrease in the serum miRNA-199b expression level. In addition, there was a negative correlation between them in patients with IBS and its different subtypes when compared with healthy controls. © 2016 IUBMB Life, 68(5):335-342, 2016.

Structure-Based Discovery of Novel and Selective 5-Hydroxytryptamine 2B Receptor Antagonists for the Treatment of Irritable Bowel Syndrome

Here we employed structure-based ligand discovery techniques to explore a recently determined crystal structure of the 5-hydroxytryptamine 2B (5-HT2B) receptor. Ten compounds containing a novel chemical scaffold were identified; among them, seven molecules were active in cellular function assays with the most potent one exhibiting an IC50 value of 27.3 nM. We then systematically probed the binding characteristics of this scaffold by designing, synthesizing, and testing a series of structural modifications. The structure-activity relationship studies strongly support our predicted binding model. The binding profiling across a panel of 11 5-HT receptors indicated that these compounds are highly selective for the 5-HT2B receptor. Oral administration of compound 15 (30 mg/kg) produced significant attenuation of visceral hypersensitivity in a rat model of irritable bowel syndrome (IBS). We expect this novel scaffold will serve as the foundation for the development of 5-HT2B antagonists for the treatment of IBS.

Microbes, molecular mimicry and molecules of mood and motivation

The hypothesis proposed is that functional disorders, such as irritable bowel syndrome, chronic fatigue syndrome and anorexia nervosa are caused by auto-antibodies to neuronal proteins induced by molecular mimicry with microbial antigens. The age incidence of these conditions, the marked female excess, increase with economic and technological advance, precipitation by infection, and the paucity of histological changes are all consistent with the hypothesis. It can be tested directly using human sera to search for cross reaction with brain proteins in model systems such as Drosophila melanogaster. The conditions might be amenable to treatment using pooled immunoglobulin. Identification and elimination from the microbial flora of the bacteria that express the cross reacting antigens should be possible.

Emerging drug for diarrhea predominant irritable bowel syndrome

INTRODUCTION

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders with a 9 - 23% prevalence estimated in the general population. Patients can be subdivided into those who tend to have predominant diarrhea (IBS-D) or predominant constipation (IBS-C). Total annual productivity loss related to IBS in US is estimated at $205 million, with a significant impairment of health-related quality of life. A gold standard for the treatment of IBS is not established. Symptoms might improve with the use of few drugs and behavioral therapy, however, data concerning efficacy, safety and tolerability are limited. Therefore, development and validation of new therapies targeting at the molecular level are widely awaited.

AREAS COVERED

We will specifically describe in this review Phase II and Phase III trials, with specific focus on treatment of IBS-D patients. Unfortunately, it is difficult to draw definite conclusions from Phase II and Phase III trials, because of the known high placebo effect.

EXPERT OPINION

Drugs active on opioid receptor subtypes and neurokinin (NK) receptors seem to be the most promising, but substantial progress of information in this field is still needed. The achievement of more insights on the pathogenesis of IBS could surely better drive and target the therapy, but still strong efforts are awaited.

Epidemiological features of irritable bowel syndrome and its subtypes among Iranian adults

BACKGROUND

The epidemiological features of irritable bowel syndrome (IBS) have not been properly investigated in Iran. Also, worldwide there is limited knowledge about the characteristics of IBS subtypes. The aim of the study was to explore the epidemiological features of IBS and its subtypes among Iranian adults.

METHODS

This is a cross-sectional study in Iranian adults living in Isfahan province. Demographic characteristics and common gastrointestinal symptoms were assessed using a self-administered modified Persian version of the Rome III questionnaire.

RESULTS

In 4763 subjects aged 19-70 years the overall prevalence of IBS was 21.5%. IBS was more prevalent in women than men (24.0 vs. 18.3%, P<0.001). In multivariate analysis, being married was associated with 27% increased odds of IBS (95% confidence interval: 1.03-1.57, P<0.05). However, IBS was not associated with age (P=0.71) or educational attainment (P=0.61). Constipation-predominant IBS (IBS-C) was the most prevalent subtype of IBS followed by mixed IBS (IBS-M), diarrhea-predominant IBS (IBS-D), and unsubtyped IBS. Female gender was associated with IBS-C while male gender was associated with IBS-D and IBS-M.

CONCLUSION

IBS is highly prevalent among Iranian adults, affecting particularly women in whom IBS-C is the most prevalent subtype.

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.

Irritable bowel syndrome: Pathogenesis, diagnosis, treatment, and evidence-based medicine

Irritable bowel syndrome (IBS) is a chronic and debilitating functional gastrointestinal disorder that affects 9%-23% of the population across the world. The percentage of patients seeking health care related to IBS approaches 12% in primary care practices and is by far the largest subgroup seen in gastroenterology clinics. It has been well documented that these patients exhibit a poorer quality of life and utilize the health care system to a greater degree than patients without this diagnosis. The pathophysiology of IBS is not clear. Many theories have been put forward, but the exact cause of IBS is still uncertain. According to the updated ROME III criteria, IBS is a clinical diagnosis and presents as one of the three predominant subtypes: (1) IBS with constipation (IBS-C); (2) IBS with diarrhea (IBS-D); and (3) mixed IBS (IBS-M); former ROME definitions refer to IBS-M as alternating IBS (IBS-A). Across the IBS subtypes, the presentation of symptoms may vary among patients and change over time. Patients report the most distressing symptoms to be abdominal pain, straining, myalgias, urgency, bloating and feelings of serious illness. The complexity and diversity of IBS presentation makes treatment difficult. Although there are reviews and guidelines for treating IBS, they focus on the efficacy of medications for IBS symptoms using high-priority endpoints, leaving those of lower priority largely unreported. Therefore, the aim of this review is to provide a comprehensive evidence-based review of the diagnosis, pathogenesis and treatment to guide clinicians diagnosing and treating their patients.

Cytokine and clinical response to Saccharomyces boulardii therapy in diarrhea-dominant irritable bowel syndrome: a randomized trial

INTRODUCTION

This preliminary study aimed to investigate the effects of the probiotic Saccharomyces boulardii on proinflammatory and anti-inflammatory cytokines in patients with diarrhea-dominant irritable bowel syndrome (IBS-D). The other objectives were to document any clinical improvement as judged by symptoms, quality of life, and histology.

PATIENTS AND METHODS

This was a randomized, double blind, placebo-controlled trial in which S. boulardii, 750 mg/day, or placebo was administered for 6 weeks in IBS-D patients, in addition to ispaghula husk standard treatment.

RESULTS

Thirty-seven patients received S. boulardii and 35 patients received the placebo. As compared with placebo, the S. boulardii group showed a significant decrease in blood and tissue levels of proinflammatory cytokines interleukin-8 (IL-8) and tumor necrosis factor-α (P<0.001) and an increase in anti-inflammatory IL-10 levels, as well as an increase in the tissue IL-10/IL-12 ratio (P<0.001). No significant change in the blood and tissue levels of cytokines was found in the placebo group. Bowel-related IBS-D symptoms reported in the patients' daily diary improved in both groups. However, overall improvement in the quality of life was more marked in the S. boulardii group. Although baseline histological findings were mild, an improvement was observed in the probiotic group in the lymphocyte and neutrophil infiltrates (P=0.017 and 0.018), epithelial mitosis (P=0.003), and intraepithelial lymphocytes (P=0.024). No serious adverse events were found in either group.

CONCLUSION

S. boulardii with ispaghula husk was superior to placebo with ispaghula husk in improving the cytokine profile, histology, and quality of life of patients with IBS-D. These preliminary results need to be confirmed in a well-powered trial.