Pathogenic factors involved in the development of irritable bowel syndrome: focus on a microbial role

Efficacy and safety of Chinese medicine JCM-16021 for diarrhea-predominant irritable bowel syndrome: study protocol for a multi-center, randomized, double-blind, placebo controlled clinical trial

BACKGROUND

Irritable bowel syndrome (IBS) is a common gastrointestinal functional disease. Adults with IBS may experience abdominal pain, change of bowel habits, and abnormal stool form without organic disease. IBS can seriously affect their work productivity and quality of life, especially diarrhea-predominant irritable bowel syndrome (IBS-D). The Chinese medicine JCM-16021 has been shown to be potentially effective in improving the symptoms of IBS-D based on a small scale clinical trial. Hence, a large scale clinical study is designed to further evaluate the efficacy and safety of the Chinese medicine JCM-16021 for IBS-D with traditional Chinese medicine (TCM) pattern of Liver Stagnation and Spleen Deficiency (LSSD).

METHODS

This study is a multi-center, randomized, double-blind, placebo-controlled clinical trial. 392 eligible participants will be enrolled with 2-week run-in, 8-week treatment and 8-week follow-up. After run-in period, participants will be randomized to receive either the Chinese medicine JCM-16021 or placebo for 8 weeks, and will have post-treatment follow up for another 8 weeks. The primary outcome is the improvement rate on the global assessment of improvement (GAI) at week 10. The secondary outcomes consist of changes of IBS-D symptoms, TCM pattern improvement, IBS-Quality of Life (IBS-QoL), IBS-Symptom Severity Score (IBS-SSS), safety, etc. RESULTS: A standard protocol has been developed for the study. The protocol will provided a detailed procedure to conduct a clinical trial and verify if the Chinese medicine JCM-16021 would significantly improve the overall symptoms of IBS-D with LSSD pattern of TCM by relieving abdominal pain, reducing stool frequency, improving the stool consistency and improving quality of life. The consolidated evidence from the study can shed light on the treatment of IBS-D with Chinese medicine.

CONCLUSION

The protocol will provide details for investigators about the study following SPIRIT Statement. High-quality evidence on the efficacy and safety of Chinese medicine JCM-16021 for IBS-D will be provided through strict compliance with the protocol.

TRIAL REGISTRATION

ClinicalTrial.gov identifier: NCT03457324. Registered 8 February 2018, https://clinicaltrials.gov/ct2/show/NCT03457324?term=NCT03457324&draw=2&rank=1.

Research on Correlation Between Psychological Factors, Mast Cells, and PAR-2 Signal Pathway in Irritable Bowel syndrome

PURPOSE

The study aimed to explore the level of psychological stress factors, mast cell (MC), and neuropeptide in the occurrence of irritable bowel syndrome (IBS) and the correlation among them, and to identify representative and effective indicators for the pathogenesis and clinical medication development of IBS.

SUBJECTS AND METHODS

Twenty-eight patients (20-64 years old) with diarrhea-predominant IBS (IBS-D) were included in the IBS-D group and 8 healthy subjects (35-63 years old) were enrolled in the control group. All subjects accepted the colonoscopic biopsies, self-rating depression scale (SDS) and self-rating anxiety scale (SAS) assessment. MC degranulation, neuropeptide S (NPS), neuropeptide Y (NPY), NPY receptor 2 (NPY2R) and Protease-activated receptor 2 (PAR-2) in colon tissues were performed by Strept Avidin-Biot complex (SABC) immunohistochemistry. Enzyme-linked immunosorbent assay (ELISA) detection was used to test the expression of NPS and NPY in peripheral blood plasma and colon tissues. Western blot was applied to examine the level of NPY2R and PAR-2.

RESULTS

The level of anxiety and depression of patients with IBS-D was more serious than that in the control. The expression of NPS, NPY and NPY2R was down-regulated in the IBS-D. The total MC and tryptase-positive MC increased significantly in the colon tissue of IBS-D and the expression level of PAR-2 was significantly up-regulated.

CONCLUSION

There has been a close connection among those indicators that the activated MC may up-regulate the function of PAR-2, resulting in the change of neuropeptide (NPS and NPY), successively leading to clinical symptoms and psychological negative changes in the IBS.

Gastrointestinal Microbiome - What We Need to Know in Clinical Practice

Human gut microbiota plays an important role in individual health. When the balance between host and gut microbiota is disrupted, changes in microbiota composition and function occur, which is referred as dysbiosis. Environmental factors as diet, proton pump inhibitors, and antibiotics can lead to a permanent dysbiotic disruption. Clarification of these imbalances was made possible by recent advances in genome sequencing methods that supported acknowledgment of the interplay between microbiome and intestinal and extraintestinal disorders. This review focuses on the microbiota impact in inflammatory bowel disease, gastric cancer, colorectal cancer, nonalcoholic fatty liver disease (NAFLD), irritable bowel syndrome (IBS), and Clostridium difficile infection (CDI). Furthermore, novel therapies are summarized. Fecal microbiota transplant (FMT) is a successful and established therapy in recurrent CDI, and its application in other dysbiosis-related diseases is attracting enormous interest. Pre- and probiotics target microbial rebalance and have positive effects mainly in NAFLD, ulcerative colitis, IBS, and CDI patients. Promising anticarcinogenic effects have also been demonstrated in animal models. The literature increasingly describes microbial changes in many dysbiotic disorders and shows what needs to be treated. However, probiotics and FMT application in clinical practice suffers from a shortage of randomized controlled trials with standardized therapy regimens to support their recommendation.

A randomized placebo-controlled clinical trial of a multi-strain probiotic formulation (Bio-Kult®) in the management of diarrhea-predominant irritable bowel syndrome

Background

Accumulating evidence supports the view that an imbalance of gut bacteria contributes to IBS, and that increasing the mass of beneficial species may reduce the numbers of pathogenic bacteria and help alleviate symptoms.

Methods

In this double-blind trial 400 adult patients with moderate-to-severe symptomatic diarrhea-predominant IBS (IBS-D) were randomized to treatment with the multi-strain probiotic Bio-Kult® (14 different bacterial strains) or placebo for 16 weeks. The change in severity and frequency of abdominal pain was the primary outcome measure.

Results

Probiotic treatment significantly improved the severity of abdominal pain in patients with IBS-D. A 69% reduction for probiotic versus 47% for placebo (p < 0.001) equates to a 145 point reduction on the IBS-severity scoring system (IBS-SSS). The proportion of patients who rated their symptoms as moderate-to-severe was reduced from 100% at baseline to 14% for the multi-strain probiotic at follow-up (month 5) versus 48% for placebo (p < 0.001). Also, the number of bowel motions per day from month 2 onwards was significantly reduced in the probiotic group compared with the placebo group (p < 0.05). In addition to relieving symptoms, the probiotic markedly improved all dimensions of quality of life in the 34-item IBS-Quality of Life (IBS-QoL) questionnaire. No serious adverse events were reported.

Conclusions

The multi-strain probiotic was associated with significant improvement in symptoms in patients with IBS-D and was well-tolerated. These results suggest that probiotics confer a benefit in IBS-D patients which deserves further investigation.

Trial registration

[Clinicaltrials.gov NCT03251625; retrospectively registered on August 9, 2017].

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-018-0788-9) contains supplementary material, which is available to authorized users.

Therapeutic Effects of Low-dose Bismuth Subcitrate on Symptoms and Health-related Quality of Life in Adult Patients with Irritable Bowel Syndrome: A Clinical Trial

OBJECTIVE

Irritable bowel syndrome (IBS) is a chronic functional disorder of the gastrointestinal tract that causes abdominal pain or discomfort and alters bowel with no organic abnormalities. Treatment options for IBS have increased in number in the past decade, and clinicians should not be limited to use only conventional treatments to cure it. This article is a placebo-controlled clinical trial to assess the therapeutic effects of low-dose bismuth subcitrate on symptoms and the health-related quality of life in adult patients with IBS.

METHODS

This clinical trial was done during July 2015 to January 2016 in Isfahan, Iran. For each of three subtypes (IBS-constipation dominant, IBS-diarrhea dominant [IBS-D], and IBS-mixed), we included patients with IBS aged 18-70 years, diagnosed according to the Rome III criteria. In this study, 129 eligible patients were enrolled, of which 119 continued on the protocol to the end of study. They were allocated in placebo group (Group A) and intervention group (Group B). The medication for Group B was mebeverine and bismuth subcitrate and for Group A was mebeverine and placebo of bismuth subcitrate. Initially, the patients of both groups completed IBS-related questionnaires (IBS-quality of life, IBS-severity scoring system), then given drugs for a 4-week period (1st on-drug period). Then, both groups were given only mebeverine hydrochloride 200 mg capsule for another 4 weeks (off-drug period). At last, Group A and Group B were given medication (2nd on-drug period), the same as 1st on-drug period.

FINDINGS

With respect to quality of life, the trend of IBS-QOL score changed significantly during the study period in both the intervention and placebo groups; however, no significant differences were observed between the two groups (P < 0.005). In subgroups analysis, quality of life significantly improved in IBS-D during the study from the first measurement to the end of study (P = 0.004). The trends of changes in the severity of pain during the study between the intervention and control group were significantly different (P = 0.018).

CONCLUSION

According to our study, IBS-D patients' symptoms improved significantly with bismuth therapy. We found that adding low-dose bismuth to mebeverine in nonresponsive IBS patients in conventional treatment could be helpful.

Gut dysbiosis and irritable bowel syndrome: The potential role of probiotics

OBJECTIVE

To discuss the role of gut dysbiosis in the development of irritable bowel syndrome (IBS) and the impact of probiotics as a potential therapeutic measure.

METHODS

PubMed was used to search for all of the studies published over the last 15 years using the key words: "irritable bowel syndrome" and "gut dysbiosis" or "probiotic". More than 800 articles were found, but only those published in English or providing evidence-based data were included in the evaluation.

RESULTS

IBS is a common disease for which no resolutive therapy is presently available. In recent years, strong evidence of a possible relationship between modifications of the gut microbiota composition and development of IBS has been collected. Moreover, the evidence showed that attempts to treat acute infectious and post-antibiotic gastroenteritis with some probiotics were significantly effective in a great number of patients, leading many experts to suggest the use of probiotics to address all of the clinical problems associated with IBS.

CONCLUSION

The available data are promising, but presently, a precise definition of which probiotic or which mixture of probiotics is effective cannot be made. Moreover, the dose and duration of treatment has not been established. Finally, we do not know whether probiotic treatment should be different according to the type of IBS. Further studies are needed before probiotics can be considered a reliable treatment for IBS.

Dietary Triggers in Irritable Bowel Syndrome: Is There a Role for Gluten?

A tight link exists between dietary factors and irritable bowel syndrome (IBS), one of the most common functional syndromes, characterized by abdominal pain/discomfort, bloating and alternating bowel habits. Amongst the variety of foods potentially evoking "food sensitivity", gluten and other wheat proteins including amylase trypsin inhibitors represent the culprits that recently have drawn the attention of the scientific community. Therefore, a newly emerging condition termed non-celiac gluten sensitivity (NCGS) or nonceliac wheat sensitivity (NCWS) is now well established in the clinical practice. Notably, patients with NCGS/NCWS have symptoms that mimic those present in IBS. The mechanisms by which gluten or other wheat proteins trigger symptoms are poorly understood and the lack of specific biomarkers hampers diagnosis of this condition. The present review aimed at providing an update to physicians and scientists regarding the following main topics: the experimental and clinical evidence on the role of gluten/wheat in IBS; how to diagnose patients with functional symptoms attributable to gluten/wheat sensitivity; the importance of double-blind placebo controlled cross-over trials as confirmatory assays of gluten/wheat sensitivity; and finally, dietary measures for gluten/wheat sensitive patients. The analysis of current evidence proposes that gluten/wheat sensitivity can indeed represent a subset of the broad spectrum of patients with a clinical presentation of IBS.

Microbial influences on hormesis, oncogenesis, and therapy: A review of the literature

Utilization of environmental stimuli for growth is the main factor contributing to the evolution of prokaryotes and eukaryotes, independently and mutualistically. Epigenetics describes an organism's ability to vary expression of certain genes based on their environmental stimuli. The diverse degree of dose-dependent responses based on their variances in expressed genetic profiles makes it difficult to ascertain whether hormesis or oncogenesis has or is occurring. In the medical field this is shown where survival curves used in determining radiotherapeutic doses have substantial uncertainties, some as large as 50% (Barendsen, 1990). Many in-vitro radiobiological studies have been limited by not taking into consideration the innate presence of microbes in biological systems, which have either grown symbiotically or pathogenically. Present in-vitro studies neglect to take into consideration the varied responses that commensal and opportunistic pathogens will have when exposed to the same stimuli and how such responses could act as stimuli for their macro/microenvironment. As a result many theories such as radiation carcinogenesis explain microscopic events but fail to describe macroscopic events (Cohen, 1995). As such, this review shows how microorganisms have the ability to perturb risks of cancer and enhance hormesis after irradiation. It will also look at bacterial significance in the microenvironment of the tumor before and during treatment. In addition, bacterial systemic communication after irradiation and the host's immune responses to infection could explain many of the phenomena associated with bystander effects. Therefore, the present literature review considers the paradigms of hormesis and oncogenesis in order to find a rationale that ties them all together. This relationship was thus characterized to be the microbiome.

Profile of rifaximin and its potential in the treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by recurrent abdominal pain and abnormal bowel patterns. Alteration in gut flora, visceral hypersensitivity, and abnormal bowel motility are among numerous factors in the complex pathophysiology of IBS. Antibiotics have been used adjunctively to treat IBS for many years but are associated with various systemic side effects. Rifaximin is a nonabsorbable, broad-spectrum antimicrobial that inhibits bacterial RNA synthesis by binding the β-subunit of microbial RNA polymerase. It targets the gastrointestinal tract and works by reducing the quantity of gas-producing bacteria and altering the predominant species of bacteria present. In vivo animal studies suggest additional beneficial mechanisms of rifaximin, including reducing mucosal inflammation and visceral hypersensitivity. Clinical studies have demonstrated that rifaximin improves symptoms associated with IBS, such as bloating, flatulence, stool consistency, and abdominal pain, and has a side-effect profile similar to placebo. Although additional investigation into optimal dosing, treatment duration, and potential resistance is required, rifaximin presents as a safe and beneficial addition to the current management options for IBS.

Faecalibacterium prausnitzii prevents physiological damages in a chronic low-grade inflammation murine model

BACKGROUND

The human gut houses one of the most complex and abundant ecosystems composed of up to 10(13)-10(14) microorganisms. The importance of this intestinal microbiota is highlighted when a disruption of the intestinal ecosystem equilibrium appears (a phenomenon called dysbiosis) leading to an illness status, such as inflammatory bowel diseases (IBD). Indeed, the reduction of the commensal bacterium Faecalibacterium prausnitzii (one of the most prevalent intestinal bacterial species in healthy adults) has been correlated with several diseases, including IBD, and most importantly, it has been shown that this bacterium has anti-inflammatory and protective effects in pre-clinical models of colitis. Some dysbiosis disorders are characterized by functional and physiological alterations. Here, we report the beneficial effects of F. prausnitzii in the physiological changes induced by a chronic low-grade inflammation in a murine model. Chronic low-grade inflammation and gut dysfunction were induced in mice by two episodes of dinitro-benzene sulfonic acid (DNBS) instillations. Markers of inflammation, gut permeability, colonic serotonin and cytokine levels were studied. The effects of F. prausnitzii strain A2-165 and its culture supernatant (SN) were then investigated.

RESULTS

No significant differences were observed in classical inflammation markers confirming that inflammation was subclinical. However, gut permeability, colonic serotonin levels and the colonic levels of the cytokines IL-6, INF-γ, IL-4 and IL-22 were higher in DNBS-treated than in untreated mice. Importantly, mice treated with either F. prausnitzii or its SN exhibited significant decreases in intestinal permeability, tissue cytokines and serotonin levels.

CONCLUSIONS

Our results show that F. prausnitzii and its SN had beneficial effects on intestinal epithelial barrier impairment in a chronic low-grade inflammation model. These observations confirm the potential of this bacterium as a novel probiotic treatment in the management of gut dysfunction and low-grade inflammation.

Review article: evidence for the role of gut microbiota in irritable bowel syndrome and its potential influence on therapeutic targets

BACKGROUND

Irritable bowel syndrome (IBS) is a prevalent gastrointestinal disease with a substantial social and economic burden. Treatment options remain limited and research on the aetiology and pathophysiology of this multifactorial disease is ongoing.

AIM

To discuss the potential role of gut microbiota in the pathophysiology of IBS and to identify possible interactions with pathophysiologic targets in IBS.

METHODS

Articles were identified via a PubMed database search ['irritable bowel syndrome' AND (anti-bacterial OR antibiotic OR flora OR microbiota OR microflora OR probiotic)]. English-language articles were screened for relevance. Full review of publications for the relevant studies was conducted, including additional publications that were identified from individual article reference lists.

RESULTS

The role of gut microbiota in IBS is supported by varying lines of evidence from animal and human studies. For example, post-infectious IBS in humans is well documented. In addition, certain probiotics and nonsystemic antibiotics appear to be efficacious in the treatment of IBS. Mechanisms involved in improving IBS symptoms likely go beyond mere changes in the composition of the gut microbiota, and accumulating animal data support the interplay of microbiota with other IBS targets, such as the gut-brain axis, visceral hypersensitivity, mucosal inflammation and motility.

CONCLUSION

The role of the gut microbiota is still being elucidated; however, it appears to be one of several important factors that contributes to the aetiology and pathophysiology of the irritable bowel syndrome.

Gut microbiota and gastrointestinal health: current concepts and future directions

BACKGROUND

The microbial community of the human gut - the enteric microbiota - plays a critical role in functions that sustain health and is a positive asset in host defenses. In recent years, our understanding of this so-called human 'super organism' has advanced, following characterization of fecal metagenomes which identified three core bacterial enterotypes, and based on basic and clinical research into the impact and consequences of microbiota biodiversity and change on gastrointestinal disorders and diseases.

PURPOSE

This article considers current knowledge and future perspectives on the make-up and function of human gut microbiota, with a particular focus on altered microbiota and gastrointestinal disorders, nutritional influences on the gut microbiota, and the consequences for gastrointestinal health, as well as improved understanding of gut-microbiota-brain communication.

Relationship among food intolerance, severity of symptoms and the number of mast cells in the ileocecal junction in patients with diarrhea-predominant irritable bowel syndrome

AIM: To analyze the relationship among food intolerance, severity of symptoms and the number of mucosal mast cells (MCs) in the ileocecal junction (ICJ) in patients with diarrhea-predominant irritable bowel syndrome (D-IBS), and to explore the influence of food intolerance on the pathogenesis of D-IBS.

METHODS: Twenty-two patients with D-IBS fulfilling the Rome III criteria and 21 asymptomatic healthy controls underwent colonoscopy in which two adjacent biopsy samples were taken from the ICJ. Mucosal MCs were detected by toluidine blue staining. The Food Intolerance Questionnaire was used to evaluate the perceived food intolerance status of D-IBS patients and controls. The Functional Bowel Disorder Severity Index (FBDSI) and IBS Symptom Severity Scale (IBS-SSS) were used to evaluate the severity of symptoms in D-IBS patients. The relationship among the scores of FBDSI and IBS-SSS, the number of MCs and the scores of food intolerance in D-IBS patients was analyzed.

RESULTS: The number of mucosal MCs in the ICJ was significantly higher in patients with D-IBS than in controls (4.68 ± 0.55/HP vs 1.33 ± 0.54/HP, P < 0.001). Compared to controls, perceived FI was more frequent in patients with D-IBS (P < 0.05). The scores of FBDSI and IBS-SSS were positively correlated with that of food intolerance in D-IBS patients (FBDSI: r = 0.992, P < 0.001; IBS-SSS: r = 0.970, P < 0.001), and with the number of mucosal MCs in the ICJ (FBDSI: r = 0.957, P < 0.001; IBS-SSS: r = 0.985, P < 0.001). The scores of food intolerance in D-IBS patients were positively correlated with the number of mucosal MCs in the ICJ (r = 0.964, P < 0.001). The number of mucosal MCs in the ICJ were significantly higher in healthy subjects with self-reported food intolerance than in those without food intolerance (P < 0.05).

CONCLUSION: The symptoms of D-IBS are positively correlated with increased number of enteric mucosal MCs which might be caused by food antigen. Food intolerance is more frequent in D-IBS patients than in controls. D-IBS symptoms may be caused or exacerbated by food intolerance.