Probiotic Therapy of the Irritable Bowel Syndrome: Why Is the Evidence Still Poor and What Can Be Done About It?

Effects of Probiotics on Neurodegenerative Disease-Related Symptoms and Systemic Inflammation: A Systematic Review

In recent years, probiotics, as a class of biologically active microorganisms, have increasingly attracted attention for their potential in treating neurodegenerative diseases (NDDs). To comprehensively assess the effects of probiotics on clinical symptoms and systemic inflammation regulation in various NDDs, this systematic review conducted a detailed search of the Cochrane Library, Embase, PubMed, and Web of Science databases, ultimately including 22 eligible randomized controlled trials (RCTs), with 4 RCTs for Alzheimer's Disease (AD), 10 RCTs for Parkinson's Disease (PD), 2 RCTs for Multiple Sclerosis (MS), and 2 RCTs for Mild Cognitive Impairment (MCI), and intervention durations ranging from 4 to 16 weeks. The comprehensive analysis indicates that probiotics help improve clinical symptoms related to NDDs, including gastrointestinal function, cognitive function, quality of life, and mental health. Additionally, probiotics generally have a positive effect on reducing systemic inflammation and enhancing antioxidant capacity in patients. In conclusion, existing evidence supports the promising potential of probiotics in treating NDDs. However, further large-scale, high-quality studies are needed to explore specific differences in efficacy among various probiotic strains, dosages, and modes of administration. Moreover, considering that lifestyle and dietary habits may modulate the effects of probiotics, these external factors should also be included in research considerations to gain a more comprehensive understanding of the mechanisms and application strategies of probiotics in NDDs treatment.

Probiotic, prebiotic, synbiotic and fermented food supplementation in psychiatric disorders: A systematic review of clinical trials

The use of probiotics, prebiotics, synbiotics or fermented foods can modulate the gut-brain axis and constitute a potentially therapeutic intervention in psychiatric disorders. This systematic review aims to identify current evidence regarding these interventions in the treatment of patients with DSM/ICD psychiatric diagnoses. Forty-seven articles from 42 studies met the inclusion criteria. Risk of bias was assessed in all included studies. Major depression was the most studied disorder (n = 19 studies). Studies frequently focused on schizophrenia (n = 11) and bipolar disorder (n = 5) and there were limited studies in anorexia nervosa (n = 4), ADHD (n = 3), Tourette (n = 1), insomnia (n = 1), PTSD (n = 1) and generalized anxiety disorder (n = 1). Except in MDD, current evidence does not clarify the role of probiotics and prebiotics in the treatment of mental illness. Several studies point to an improvement in the immune and inflammatory profile (e.g. CRP, IL6), which may be a relevant mechanism of action of the therapeutic response identified in these studies. Future research should consider lifestyle and dietary habits of patients as possible confounders that may influence inter-individual treatment response.

Probiotics Show Promise as a Novel Natural Treatment for Neurological Disorders

Probiotics are beneficial microorganisms shown to improve human health when consumed regularly and in sufficient quantities. Numerous health benefits can be attained by possessing important metabolites with nutritional and medicinal qualities. It has been shown through scientific research that these living microbial consortiums can influence a variety of mental health outcomes, including but not limited to anxiety, depression, cognitive processes, stress responses, and behavioral patterns. Selected strains of bacteria and yeasts control how the central nervous system (CNS) communicates with the gut-brain axis (GBA) through neuronal, humoral, and metabolic pathways to ease mood. Psychobiotics are substances that can affect the digestive system as well as mood and anxiety. There is scant evidence to validate the beneficial effects of psychiatric drugs in treating neurological diseases or disorders. The therapeutic method of research into psychobiotics opens exciting prospects for the future of the field of development. This review compiles the current evidence available in the scientific literature on the use of probiotics to influence neurological disorders.

Effects of Probiotics on Autism Spectrum Disorder in Children: A Systematic Review and Meta-Analysis of Clinical Trials

Many studies have explored the efficacy of probiotics on autism spectrum disorder (ASD) in children, but there is no consensus on the curative effect. This systematic review and meta-analysis aimed to comprehensively investigate whether probiotics could improve behavioral symptoms in children with ASD. A systematic database search was conducted and a total of seven studies were included in the meta-analysis. We found a nonsignificant overall effect size of probiotics on behavioral symptoms in children with ASD (SMD = −0.24, 95% CI: −0.60 to 0.11, p = 0.18). However, a significant overall effect size was found in the subgroup of the probiotic blend (SMD = −0.42, 95% CI: −0.83 to −0.02, p = 0.04). Additionally, these studies provided limited evidence for the efficacy of probiotics due to their small sample sizes, a shorter intervention duration, different probiotics used, different scales used, and poor research quality. Thus, randomized, double-blind, and placebo-controlled studies following strict trial guidelines are needed to precisely demonstrate the therapeutic effects of probiotics on ASD in children.

Can probiotic gargles reduce post-tonsillectomy morbidity in adult patients? A pilot, triple-blind, randomised, controlled trial and feasibility study

OBJECTIVE

This study aimed to determine the efficacy of probiotic gargles compared with placebo gargles on reducing post-tonsillectomy morbidity in adults.

METHOD

This was a triple-blind, randomised, controlled trial and feasibility study. Thirty adults underwent elective tonsillectomy and were randomly assigned to receive either probiotic or placebo gargles for 14 days after surgery. Daily pain scores and requirement of analgesia were measured for 14 days post-operatively. Secondary outcomes assessed probiotic safety and tolerability and the feasibility of the trial.

RESULTS

The probiotic group experienced less pain at rest on day 2. However, the amount of oxycodone (5 mg) tablets used was greater in the probiotic group compared with placebo. There were no statistically significant differences in the frequency of adverse effects between both groups. This trial was feasible.

CONCLUSION

This pilot study suggested that probiotic gargles do not reduce post-tonsillectomy pain or bleeding, highlighting the importance of pilot and feasibility studies in clinical research.

New Insights on the Role of Bioactive Food Derivatives in Neurodegeneration and Neuroprotection

Over the last three decades, neurodegenerative diseases have received increasing attention due to their frequency in the aging population and the social and economic burdens they are posing. In parallel, an era's worth of research in neuroscience has shaped our current appreciation of the complex relationship between nutrition and the central nervous system. Particular branches of nutrition continue to galvanize neuroscientists, in particular the diverse roles that bioactive food derivatives play on health and disease. Bioactive food derivatives are nowadays recognized to directly impact brain homeostasis, specifically with respect to their actions on cellular mechanisms of oxidative stress, neuroinflammation, mitochondrial dysfunction, apoptosis and autophagy. However, ambiguities still exist regarding the significance of the influence of bioactive food derivatives on human health. In turn, gut microbiota dysbiosis is emerging as a novel player in the pathogenesis of neurodegenerative diseases. Currently, several routes of communication exist between the gut and the brain, where molecules are either released in the bloodstream or directly transported to the CNS. As such, bioactive food derivatives can modulate the complex ecosystem of the gut-brain axis, thus, targeting this communication network holds promises as a neuroprotective tool. This review aims at addressing one of the emerging aspects of neuroscience, particularly the interplay between food bioactive derivatives and neurodegeneration. We will specifically address the role that polyphenols and omega-3 fatty acids play in preventing neurodegenerative diseases and how dietary intervention complements available pharmacological approaches.

Lactococcus lactis NCDO2118 exerts visceral antinociceptive properties in rat via GABA production in the gastro-intestinal tract

Gut disorders associated to irritable bowel syndrome (IBS) are combined with anxiety and depression. Evidence suggests that microbially produced neuroactive molecules, like γ-aminobutyric acid (GABA), can modulate the gut-brain axis. Two natural strains of Lactococcus lactis and one mutant were characterized in vitro for their GABA production and tested in vivo in rat by oral gavage for their antinociceptive properties. L. lactis NCDO2118 significantly reduced visceral hypersensitivity induced by stress due to its glutamate decarboxylase (GAD) activity. L. lactis NCDO2727 with similar genes for GABA metabolism but no detectable GAD activity had no in vivo effect, as well as the NCDO2118 ΔgadB mutant. The antinociceptive effect observed for the NCDO2118 strain was mediated by the production of GABA in the gastro-intestinal tract and blocked by GABA_B receptor antagonist. Only minor changes in the faecal microbiota composition were observed after the L. lactis NCDO2118 treatment. These findings reveal the crucial role of the microbial GAD activity of L. lactis NCDO2118 to deliver GABA into the gastro-intestinal tract for exerting antinociceptive properties in vivo and open avenues for this GRAS (Generally Recognized As safe) bacterium in the management of visceral pain and anxious profile of IBS patients.

Effect of Bifidobacterium longum 35624 on disease severity and quality of life in patients with irritable bowel syndrome

BACKGROUND

Bifidobacterium longum 35624 has shown efficacy in improving irritable bowel syndrome (IBS) symptoms compared with placebo in double-blind randomized studies. However, few data are available from real-life clinical practice or from studies that used Rome IV criteria to diagnose IBS.

AIM

To assess the effect of B. longum 35624 on IBS severity and quality of life in a real-life setting.

METHODS

From November 2018 to January 2020, 278 patients with IBS (according to Rome IV criteria) were enrolled in a prospective, open-label, multicenter observational study by private practice gastroenterologists to received one capsule of B. longum 35624 (10⁹ colony-forming units) per day for 30 d. Participation in the study was independently proposed to patients during spontaneous consultations. Disease severity (assessed by the IBS severity scoring system) and patient quality of life (assessed by the IBS quality of life questionnaire) were compared between the inclusion visit (baseline) and the visit at the end of 30 d of treatment. The characteristics of patients were described at baseline. Continuous variables comparisons between inclusion and end-of-treatment visits were performed using the t-test and Kruskal-Wallis test. Categorical variables comparisons were performed using the χ2 test.

RESULTS

A total of 233 patients, with a mean age of 51.4 years and composed of 71.2% women, were included in the study. Of these patients, 48.1% had moderate IBS and 46.4% had severe IBS. After a 30-d treatment period with one B. longum 35624 capsule per day, a significant decrease in IBS severity was observed compared to baseline (mean ± SD, IBS severity scoring system scores: 208 ± 104 vs 303 ± 81, P < 0.001) and 57% of patients moved to lower severity categories or achieved remission. The quality of life of patients was also improved by the treatment (IBS Quality of Life questionnaire score: 68.8 ± 20.9 vs 60.2 ± 20.5; P < 0.001) and 63.8% of patients were satisfied with the treatment.

CONCLUSION

Thirty days of treatment with B. longum 35624 reduces disease severity and improves the quality of life of patients with IBS, particularly those with the most severe forms of IBS.

Effect of Probiotics on Psychiatric Symptoms and Central Nervous System Functions in Human Health and Disease: A Systematic Review and Meta-Analysis

Background: The gut microbiota impacts on central nervous system (CNS) function via the microbiota–gut–brain axis. Thus, therapeutics targeting the gut microbiota such as probiotics have the potential for improving mental health. This meta-analysis synthesizes the evidence regarding the impacts of probiotics on psychological well-being, psychiatric symptoms and CNS functioning. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were applied for executing this review using the databases PubMed, Web of Science and Cochrane Library. The data were summarized at qualitative and quantitative level. Results: Fifty-four randomized placebo-controlled studies were included, of which 30 were eligible for meta-analysis. If investigated, the probiotics mostly exerted effects on CNS function. Most probiotics did not affect mood, stress, anxiety, depression and psychiatric distress when compared to placebo at the qualitative level. At quantitative level, depression and psychiatric distress improved slightly in the probiotic condition (depression: mean difference −0.37 (95% CI: −0.55, −0.20); p ≤ 0.0001; psychiatric distress: mean difference −0.33 (95% CI: −0.53, −0.13); p = 0.001). Conclusions: To date it is unclear to which extent and in which specific areas next generation probiotics selected and developed for their ability to improve psychiatric condition and potentially other CNS functions are promising.

The Evolution of Human Probiotics: Challenges and Prospects

In recent years, the intestinal microbiota has been found to greatly influence a number of biological processes important for human health and longevity. Microbial composition changes easily in response to external factors, such as an unbalanced diet, lack of physical activity, and smoking. Probiotics are a key factor in maintaining the optimal composition of the intestinal microbiota. However, a number of important questions related to probiotics, such as indication for prescription, comparative efficacy of monostrain and multistrain probiotics, methods of delivery, and shelf life, remain unresolved. The aim of this review is to highlight existing issues regarding probiotic production and their prescription. The review presents the most recent findings regarding advantages and efficacy of monostrain and multistrain probiotics, preservation of probiotic strains in capsules and microcapsules, production of probiotics in the form of biofilms for improved efficacy and survival, and results of clinical studies evaluating the benefits of probiotics against different pathologies. We believe that this work will be of interest to physicians and researchers alike and will promote the development of new probiotics and ensuing regimens aimed at the treatment of various diseases.

New Avenues for Parkinson's Disease Therapeutics: Disease-Modifying Strategies Based on the Gut Microbiota

Parkinson's disease (PD) is a multifactorial neurodegenerative disorder that currently affects 1% of the population over the age of 60 years, and for which no disease-modifying treatments exist. Neurodegeneration and neuropathology in different brain areas are manifested as both motor and non-motor symptoms in patients. Recent interest in the gut-brain axis has led to increasing research into the gut microbiota changes in PD patients and their impact on disease pathophysiology. As evidence is piling up on the effects of gut microbiota in disease development and progression, another front of action has opened up in relation to the potential usage of microbiota-based therapeutic strategies in treating gastrointestinal alterations and possibly also motor symptoms in PD. This review provides status on the different strategies that are in the front line (i.e., antibiotics; probiotics; prebiotics; synbiotics; dietary interventions; fecal microbiota transplantation, live biotherapeutic products), and discusses the opportunities and challenges the field of microbiome research in PD is facing.

Effect of a Synbiotic Containing Lactobacillus paracasei and Opuntia humifusa on a Murine Model of Irritable Bowel Syndrome

The administration of a combination of probiotics and prebiotics is expected to be a promising strategy for improving irritable bowel syndrome (IBS) symptoms. This study aimed to investigate the efficacy of a synbiotic containing Lactobacillus paracasei and Opuntia humifusa extract for symptomatic improvement of IBS in a murine model and to evaluate the mechanism underlying the beneficial effects of this synbiotic. A total of 20 male Wistar rats aged 8 weeks with IBS induced by restraint stress were assigned into four groups and administered L. paracasei as a probiotic and O. humifusa extract as a prebiotic for 4 weeks. The primary outcome was stool consistency at week 4. To evaluate the mechanism underlying the beneficial effects of the synbiotic, fecal microbial analysis was conducted, and the serum corticosterone levels, tumor necrosis factor-α (TNF-α) levels in the colon tissue, and expression of tight junction proteins were investigated. All three treatment groups showed significantly lower scores for stool consistency than the control group at week 4 (all p < 0.001). When compared with the control group, the synbiotic groups showed a significantly greater abundance of L. paracasei in fecal microbial analysis, lower serum corticosterone levels, lower TNF-α levels in the colon tissue, and higher expression of tight junction proteins. This novel synbiotic containing L. paracasei and O. humifusa extract can improve the stool consistency in a murine model of IBS. It may be a promising treatment option for IBS, and human studies are warranted.

The efficacy of Bifidobacterium quadruple viable tablet in the treatment of diarrhea predominant irritable bowel syndrome: protocol for a randomized, double-blind, placebo-controlled, multicenter trial

BACKGROUND

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders characterized by recurrent abdominal pain associated with defecation or a change in bowel habits. Leading to significant negative effect on patients' quality of life and huge financial burden to health system, the management of IBS is a great challenge. Probiotics are considered as an effective therapy; however, in a lack of high-quality evidence of efficacy, no strain- and dose-specific probiotics were recommended in clinical guidelines. This study aims to evaluate the efficacy of the Bifidobacterium quadruple viable tablet in the treatment of IBS-D.

METHODS/DESIGN

A multicenter randomized controlled trial will be performed in fourteen hospitals. A total of three hundred patients who fulfill the eligibility criteria will be stratified divided into an experimental group and a control group randomly in a ratio of 1:1. The experimental group is treated with the Bifidobacterium quadruple viable tablet while the control group is treated with placebo. All the patients will receive a 4-week treatment and a 2-week follow-up. The primary outcome is the effectiveness in improving abdominal pain and stool consistency; the secondary outcome includes evaluation of overall symptom relief, frequency of defecation, bloating, urgency of defecation, remedial medication, score of IBS-QOL, and changes of microbiota and metabonomics. Physical examination, vital signs, laboratory tests, adverse events, and concomitant medication will be taken into account for intervention safety assessment during the trial.

DISCUSSION

This multicenter randomized controlled trial may provide high-quality evidence on the efficacy of the Bifidobacterium quadruple viable tablet for IBS-D on both physical and mental dimensions in China. To fill the gap of previous probiotic intervention studies, in addition, this study will also present safety assessment which will be a significant emphasis.

TRIAL REGISTRATION

ChiCTR1800017721 . Registered on 10 August 2018.

Efficacy and Safety of Probiotics, Prebiotics and Synbiotics in the Treatment of Irritable Bowel Syndrome: A systematic review and meta-analysis

Treatments that target alterations in gut microbiota may be beneficial for patients with irritable bowel syndrome (IBS). A systematic review and meta-analysis was conducted of randomised clinical trials (RCTs) evaluating the efficacy and safety of probiotics, prebiotics and synbiotics. Factors considered in the analysis included global IBS symptoms and/or abdominal pain, secondary symptoms and the frequency of adverse events. A total of 33 RCTs involving 4,321 patients were identified. Overall, probiotics significantly improved global IBS symptoms compared to placebos (standardised mean difference = −0.32, 95% confidence interval: −0.48 to −0.15; P <0.001), with significant heterogeneity between studies (I² = 72%; P <0.001). This remained apparent in both single- and multi-strain probiotic interventions as well as synbiotic formulations. However, evidence regarding prebiotics was scarce. There were no significant inter-group differences in terms of the frequency of adverse events. Future RCTs should address methodological limitations, including short follow-up periods and patient adherence.

Microbiota modulation-based therapy for luminal GI disorders: current applications of probiotics and fecal microbiota transplantation

Introduction: Alteration in the intestinal microbiota also termed as intestinal dysbiosis has been demonstrated in numerous gastrointestinal disorders linked to aberrant immune processes, acquisition of pathogenic organisms and often administration of antibiotics. Restoration of microbiota through probiotics and fecal microbiota transplantation (FMT) has gained tremendous popularity among researchers in the prevention and treatment of gastrointestinal diseases.Areas covered: In this review, studies testing the safety and efficacy of probiotics and FMT for the treatment of various infectious and inflammatory luminal gastrointestinal diseases are reviewed. Randomized control studies are given priority while important uncontrolled studies are also highlighted.Expert opinion: Probiotics have demonstrated efficacy in the prevention of antibiotic-associated diarrhea and in the eradication of Helicobacter pylori infection. Their utility in the primary and secondary prevention of Clostridioides difficile infection is debatable. The future of medicine should bring forth a personalized approach to probiotic use. FMT has revolutionized the treatment of recurrent CDI as well as severe and fulminant CDI. At the same time, it has galvanized gut microbiota research in the last decade. While FMT in ulcerative colitis appears promising, further studies on the durability and long-term safety are needed before it can be recommended in clinical practice.

Prebiotics and Probiotics in Digestive Health

As the importance of the gut microbiota in health and disease is increasingly recognized interest in interventions that can modulate the microbiota and its interactions with its host has soared. Apart from diet, prebiotics and probiotics represent the most commonly used substances taken in an effort to sustain a healthy microbiome or restore balance when it is believed bacterial homeostasis has been disturbed in disease. While a considerable volume of basic science attests to the ability of various prebiotic molecules and probiotic strains to beneficially influence host immune responses, metabolic processes and neuro-endocrine pathways, the evidence base from human studies leaves much to be desired. This translational gap owes much to the manner in which this sector is regulated but also speaks to the challenges that confront the investigator who seeks to explore microbiota modulation in either healthy populations or those who suffer from common digestive ailments. For many products marketed as probiotics, some of the most fundamental issues relating to quality control, such as characterization, formulation, viability safety are scarcely addressed.

Making Sense of … the Microbiome in Psychiatry

Microorganisms can be found almost anywhere, including in and on the human body. The collection of microorganisms associated with a certain location is called a microbiota, with its collective genetic material referred to as the microbiome. The largest population of microorganisms on the human body resides in the gastrointestinal tract; thus, it is not surprising that the most investigated human microbiome is the human gut microbiome. On average, the gut hosts microbes from more than 60 genera and contains more cells than the human body. The human gut microbiome has been shown to influence many aspects of host health, including more recently the brain.Several modes of interaction between the gut and the brain have been discovered, including via the synthesis of metabolites and neurotransmitters, activation of the vagus nerve, and activation of the immune system. A growing body of work is implicating the microbiome in a variety of psychological processes and neuropsychiatric disorders. These include mood and anxiety disorders, neurodevelopmental disorders such as autism spectrum disorder and schizophrenia, and even neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Moreover, it is probable that most psychotropic medications have an impact on the microbiome.Here, an overview will be provided for the bidirectional role of the microbiome in brain health, age-associated cognitive decline, and neurological and psychiatric disorders. Furthermore, a primer on the common microbiological and bioinformatics techniques used to interrogate the microbiome will be provided. This review is meant to equip the reader with a primer to this exciting research area that is permeating all areas of biological psychiatry research.

Focus on the use of antidepressants to treat pediatric functional abdominal pain: current perspectives

Chronic abdominal pain is frequently encountered in pediatric practice. A large proportion of cases meet Rome criteria for abdominal pain-functional gastrointestinal disorders (AP-FGIDs). These disorders are costly and, in some cases, lead to impairment of daily functioning and overall quality of life. Pathophysiologic mechanisms include early stressful events, visceral hypersensitivity, dysmotility, changes in intestinal microbiota, and altered central nervous system processing. They are considered disorders of the brain-gut interaction. The diagnosis is made on clinical grounds using symptom-based criteria (Rome criteria). Anxiety and depressive symptoms are more prevalent in patients with AP-FGIDs. Therefore, attention has been directed to the use of neuromodulators as potential interventions for AP-FGIDs. Antidepressants are one type of neuromodulators, and one of the most studied drugs for the management of AP-FGIDs in adult and pediatric population. Data available in pediatric population have significant limitations including nonuniform methodology with different study designs and primary endpoints. Evidence of the efficacy of antidepressants in the management of pediatric AP-FGIDs is not consistent. There is an urgent need for well-designed randomized clinical trials using age-appropriate validated outcome measures. Careful consideration must be given to adverse effects, particularly increased suicidal ideation.

Management of Functional Somatic Syndromes and Bodily Distress

Functional somatic syndromes (FSS), like irritable bowel syndrome or fibromyalgia and other symptoms reflecting bodily distress, are common in practically all areas of medicine worldwide. Diagnostic and therapeutic approaches to these symptoms and syndromes vary substantially across and within medical specialties from biomedicine to psychiatry. Patients may become frustrated with the lack of effective treatment, doctors may experience these disorders as difficult to treat, and this type of health problem forms an important component of the global burden of disease. This review intends to develop a unifying perspective on the understanding and management of FSS and bodily distress. Firstly, we present the clinical problem and review current concepts for classification. Secondly, we propose an integrated etiological model which encompasses a wide range of biopsychosocial vulnerability and triggering factors and considers consecutive aggravating and maintaining factors. Thirdly, we systematically scrutinize the current evidence base in terms of an umbrella review of systematic reviews from 2007 to 2017 and give recommendations for treatment for all levels of care, concentrating on developments over the last 10 years. We conclude that activating, patient-involving, and centrally acting therapies appear to be more effective than passive ones that primarily act on peripheral physiology, and we recommend stepped care approaches that translate a truly biopsychosocial approach into actual management of the patient.

Effect of probiotic Bifidobacterium bifidum G9-1 on the relationship between gut microbiota profile and stress sensitivity in maternally separated rats

Although gut microbiota and early life events are likely involved in the development of irritable bowel syndrome (IBS), it remains unclear how these factors interact in the pathophysiology of IBS. In the present study, using rats subjected to maternal separation (MS) as a model of IBS, we investigated interrelationships among gut microbiota, stress susceptibility and intestinal permeability, and examined the effect of the probiotic Bifidobacterium bifidum G9-1 (BBG9-1) on those interrelationships. When compared with the controls at postnatal day 20, MS rats showed hypercorticosteronemia, enhanced intestinal permeability and changes in gut microbiota structure. All of these changes in MS rats were prevented by treatment with BBG9-1. Although the gut microbiota profile and basal serum corticosterone level did not differ between MS and control rats at postnatal day 56, MS rats showed hypersensitivity to restraint stress in terms of serum corticosterone level and fecal frequency. However, such hypersensitivity was not observed in MS rats treated with BBG9-1. These findings suggest that MS initiates the link between gut microbiota alteration and hypersensitivity to stress and that the triggering of this process can be prevented by the treatment with the probiotic BBG9-1.

Effects of Fengliao-Changweikang in Diarrhea-predominant Irritable Bowel Syndrome Rats and Its Mechanism Involving Colonic Motility

Background/Aims

This study was designed to investigate the effect of Fengliao-Changweikang (FLCWK) in diarrhea-predominant irritable bowel syndrome (IBS-D) rats and explore its underlying mechanisms.

Methods

IBS-D model rats were induced by neonatal maternal separation (NMS) combined with restraint stress (RS). In in vivo experiments, the model rats were randomly divided into 5 groups: NMS + RS, FLCWK (low dose, middle dose, and high dose), and pinaverium bromide. The normal control (no handling) rats were classified as the NH group. The therapeutic effect of FLCWK was evaluated by fecal characteristics, electromyographic response and abdominal withdrawal reflex scores. In in vitro experiments, the model rats were randomly divided into 2 groups: NMS + RS, FLCWK (middle dose), and no handling rats were used as the NH group. The differences in basic tension and ACh-induced tension of isolated colonic longitudinal smooth muscle strips (CLSMs) among the 3 groups were observed. In addition, different inhibitors (nifedipine, TMB-8, L-NAME, methylene blue, and 4-AP) were pretreated to explore the underlying mechanisms.

Results

In in vivo experiments, fecal characteristics, electromyographic response, and abdominal withdrawal reflex scores significantly improved in the FLCWK group, compared with the NMS + RS group. In in vitro experiments, the basic tension and ACh-induced tension of CLSMs in IBS-D rats were significantly inhibited by FLCWK. After pre-treatment with different inhibitors, the ACh-induced tension of CLSMs in each group showed no significant difference.

Conclusions

FLCWK manifested curative effect in IBS-D rats by inhibiting colonic contraction. The underlying mechanisms may be related to regulatory pathway of nitric oxide/cGMP/Ca²⁺ and specific potassium channels.

Effects of Rifaximin on Central Responses to Social Stress-a Pilot Experiment

Probiotics that promote the gut microbiota have been reported to reduce stress responses, and improve memory and mood. Whether and how antibiotics that eliminate or inhibit pathogenic and commensal gut bacteria also affect central nervous system functions in humans is so far unknown. In a double-blinded randomized study, 16 healthy volunteers (27.00 ± 1.60 years; 9 males) received either rifaximin (600 mg/day) (a poorly absorbable antibiotic) or placebo for 7 days. Before and after the drug intervention, brain activities during rest and during a social stressor inducing feelings of exclusion (Cyberball game) were measured using magnetoencephalography. Social exclusion significantly affected (p < 0.001) mood and increased exclusion perception. Magnetoencephalography showed brain regions with higher activations during exclusion as compared to inclusion, in different frequency bands. Seven days of rifaximin increased prefrontal and right cingulate alpha power during resting state. Low beta power showed an interaction of intervention (rifaximin, placebo) × condition (inclusion, exclusion) during the Cyberball game in the bilateral prefrontal and left anterior cingulate cortex. Only in the rifaximin group, a decrease (p = 0.004) in power was seen comparing exclusion to inclusion; the reduced beta-1 power was negatively correlated with a change in the subjective exclusion perception score. Social stress affecting brain functioning in a specific manner is modulated by rifaximin. Contrary to our hypothesis that antibiotics have advert effects on mood, the antibiotic exhibited stress-reducing effects similar to reported effects of probiotics (supported by NeuroGUT, a EU 7th Framework Programme ITN no. 607652; ClinicalTrials.gov identifier number NCT02793193).

Dysbiosis in Functional Bowel Disorders

Functional bowel disorders (FBD) resemble a group of diseases of the gastrointestinal (GI) tract that are without a clear pathogenesis; the best known is probably the "irritable bowel syndrome" (IBS). Only recently we have been able to explore the role of the gut microbiota in FBD due to progress in microbiological analytic techniques. There are different ways to explore the role of the gut microbiota and its dysbiosis in FBD. Comparison of the microbial composition in a group of patients with FBD, for example, with IBS to a group of healthy volunteers is one way. Studies have shown that the microbiota in FBD is different from that of healthy controls, but the recorded differences are not necessarily specific for FBD, they may also occur in other diseases. Another approach to explore the role of the gut microbiota in FBD is to challenge the existing "flora" with novel bacteria (probiotics) or with nutritional substrates that stimulate bacterial growth (prebiotics). More than 60 such trials including several thousand patients have been performed in IBS. These studies have produced mixed outcome: some probiotics appear to be better than others, and some appear to work only for a part of the IBS symptoms and not for all. An extreme form of this approach is the transfer of an entire microbiota from 1 healthy person to another, called fecal microbiota transplantation. This has rarely been tested in FBD but is not without risk in benign disorders.

Current understanding of microbiota- and dietary-therapies for treating inflammatory bowel disease

Inflammatory bowel disease (IBD) is a result of chronic inflammation caused, in some part, by dysbiosis of intestinal microbiota, mainly commensal bacteria. Gut dysbiosis can be caused by multiple factors, including abnormal immune responses which might be related to genetic susceptibility, infection, western dietary habits, and administration of antibiotics. Consequently, the disease itself is characterized as having multiple causes, etiologies, and severities. Recent studies have identified >200 IBD risk loci in the host. It has been postulated that gut microbiota interact with these risk loci resulting in dysbiosis, and this subsequently leads to the development of IBD. Typical gut microbiota in IBD patients are characterized with decrease in species richness and many of the commensal, and beneficial, fecal bacteria such as Firmicutes and Bacteroidetes and an increase or bloom of Proteobacteria. However, at this time, cause and effect relationships have not been rigorously established. While treatments of IBD usually includes medications such as corticosteroids, 5-aminosalicylates, antibiotics, immunomodulators, and anti-TNF agents, restoration of gut dysbiosis seems to be a safer and more sustainable approach. Bacteriotherapies (now called microbiota therapies) and dietary interventions are effective way to modulate gut microbiota. In this review, we summarize factors involved in IBD and studies attempted to treat IBD with probiotics. We also discuss the potential use of microbiota therapies as one promising approach in treating IBD. As therapies based on the modulation of gut microbiota becomes more common, future studies should include individual gut microbiota differences to develop personalized therapy for IBD.

Bifidobacterium longum and Lactobacillus helveticus Synergistically Suppress Stress-related Visceral Hypersensitivity Through Hypothalamic-Pituitary-Adrenal Axis Modulation

Background/Aims

Visceral pain and hypothalamic-pituitary-adrenal axis (HPA) dysregulation is a common characteristic in irritable bowel syndrome (IBS) patients. Previously, we reported that a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) prevents chronic stress-mediated brain function abnormalities by attenuating the HPA axis response. Here, we compared the effect between different probiotic treatments on the perception of visceral pain during colorectal distension (CRD) following a chronic stress and the consequences to the activity of the HPA axis.

Methods

After a 2-week treatment with a combined probiotic formulation, or L. helveticus or B. longum alone in stressed mice, the visceral pain in response to CRD was recorded. The expression of glucocorticoid receptors was determined in the different brain areas involved in the stress response (hypothalamus, hippocampus, and prefrontal cortex). The plasma levels of stress hormones were also measured.

Results

A pretreatment using the combination of probiotic formulation significantly reduces the chronic stress-induced visceral hypersensitivity respectively at 0.06, 0.08, and 0.10 mL CRD volume. However, a single probiotic (B. longum or L. helveticus) administration is less effective in reducing visceral pain in stressed mice. Moreover, the expression of the glucocorticoid receptor mRNA was consistently up-regulated in several brain areas after pretreatment with a combined probiotic, which correlated with the normalization of stress response compared to the inconsistent effects of a single probiotic.

Conclusion

The combination of L. helveticus and B. longum is more effective in regulating glucocorticoid negative feedback on the HPA axis than probiotic alone and subsequently in treating stress-induced visceral pain.

Probiotics reduce repeated water avoidance stress-induced colonic microinflammation in Wistar rats in a sex-specific manner

The colonic response to stress is greater in female rats than in male rats. The aim of this study was to evaluate the effect of probiotics in the repeated water avoidance stress (rWAS)-induced colonic microinflammation model of Wistar rats in a sex-specific manner. The three groups (no-stress, WAS, and WAS with probiotics) were exposed to r-WAS for 1 h daily for 10 days, and Lactobacillus farciminis was administered by oral gavage for 10 days to animals in the probiotics group. The visceromotor response (VMR) to colorectal distension (CRD) was assessed using a barostat and noninvasive manometry before and after WAS exposure. Immunohistochemistry for mast cells and real-time polymerase chain reaction (RT-PCR) for detection of mucosal cytokines were performed using distal colon tissue after the animals were sacrificed. Significant reduction of VMR to CRD (visceral analgesia) was observed at 60 mmHg in the female WAS group (P = 0.045), but not in males. In addition, the female WAS with probiotics group showed a significantly lower colonic mucosal mast cell count in comparison to the female WAS group (P = 0.013), but this phenomenon was not observed in the male group. The colonic mucosal mRNA levels of interferon-γ (IFNR), tumor necrosis factor-α (TNFA), interleukin (IL) 6, and IL17 were higher in the female WAS group than in the male WAS group. The mRNA levels of IFNR, TNFA, and IL6 were significantly decreased in WAS females who received probiotics (all P < 0.050). In conclusion, rWAS is induced in a sex-specific manner. A 10-day-long treatment with L. farciminis is an effective therapy for rWAS-induced colonic microinflammation in female rates, but not in male rats.

Symptom Severity Following Rifaximin and the Probiotic VSL#3 in Patients with Chronic Pelvic Pain Syndrome (Due to Inflammatory Prostatitis) Plus Irritable Bowel Syndrome

This study investigated the effects of long-term treatment with rifaximin and the probiotic VSL#3 on uro-genital and gastrointestinal symptoms in patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) plus diarrhoea-predominant irritable bowel syndrome (D-IBS) compared with patients with D-IBS alone. Eighty-five patients with CP/CPPS (45 with subtype IIIa and 40 with IIIb) plus D-IBS according to the Rome III criteria and an aged-matched control-group of patients with D-IBS alone (n = 75) received rifaximin and VSL#3. The primary endpoints were the response rates of IBS and CP/CPPS symptoms, assessed respectively through Irritable Bowel Syndrome Severity Scoring System (IBS-SSS) and The National Institute of Health Chronic Prostatitis Symptom Index (NIH-CPSI), and performed at the start of therapy (V0) and three months after (V3). In IIIa prostatitis patients, the total NIH-CPSI scores significantly (p < 0.05) decreased from a baseline mean value of 21.2 to 14.5 at V3 , as did all subscales, and in the IIIb the total NIH-CPSI score also significantly decreased (from 17.4 to 15.1). Patients with IBS alone showed no significant differences in NIH-CPSI score. At V3, significantly greater improvement in the IBS-SSS and responder rate were found in IIIa patients. Our results were explained through a better individual response at V3 in IIIa prostatitis of urinary and gastrointestinal symptoms, while mean leukocyte counts on expressed prostate secretion (EPS) after prostate massage significantly lowered only in IIIa cases.

New therapeutic perspectives in irritable bowel syndrome: Targeting low-grade inflammation, immuno-neuroendocrine axis, motility, secretion and beyond

Irritable bowel syndrome (IBS) is a chronic, recurring, and remitting functional disorder of the gastrointestinal tract characterized by abdominal pain, distention, and changes in bowel habits. Although there are several drugs for IBS, effective and approved treatments for one or more of the symptoms for various IBS subtypes are needed. Improved understanding of pathophysiological mechanisms such as the role of impaired bile acid metabolism, neurohormonal regulation, immune dysfunction, the epithelial barrier and the secretory properties of the gut has led to advancements in the treatment of IBS. With regards to therapies for restoring intestinal permeability, multiple studies with prebiotics and probiotics are ongoing, even if to date their efficacy has been limited. In parallel, much progress has been made in targeting low-grade inflammation, especially through the introduction of drugs such as mesalazine and rifaximin, even if a better knowledge of the mechanisms underlying the low-grade inflammation in IBS may allow the design of clinical trials that test the efficacy and safety of such drugs. This literature review aims to summarize the findings related to new and investigational therapeutic agents for IBS, most recently developed in preclinical as well as Phase 1 and Phase 2 clinical studies.

Lactobacillus acidophilus NS1 Reduces Phosphoenolpyruvate Carboxylase Expression by Regulating HNF4α Transcriptional Activity

Probiotics have been known to reduce high-fat diet (HFD)-induced metabolic diseases, such as obesity, insulin resistance, and type 2 diabetes. We recently observed that Lactobacillus acidophilus NS1 (LNS1), distinctly suppresses increase of blood glucose levels and insulin resistance in HFD-fed mice. In the present study, we demonstrated that oral administration of LNS1 with HFD feeding to mice significantly reduces hepatic expression of phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme in gluconeogenesis which is highly increased by HFD feeding. This suppressive effect of LNS1 on hepatic expression of PEPCK was further confirmed in HepG2 cells by treatment of LNS1 conditioned media (LNS1-CM). LNS1-CM strongly and specifically inhibited HNF4α-induced PEPCK promoter activity in HepG2 cells without change of HNF4α mRNA levels. Together, these data demonstrate that LNS1 suppresses PEPCK expression in the liver by regulating HNF4α transcriptional activity, implicating its role as a preventive or therapeutic approach for metabolic diseases.

Food matters: how the microbiome and gut-brain interaction might impact the development and course of anorexia nervosa

Anorexia nervosa (AN) is one of the most common chronic illnesses in female adolescents and exhibits the highest mortality risk of all psychiatric disorders. Evidence for the effectiveness of psychotherapeutic or psychopharmacological interventions is weak. Mounting data indicate that the gut microbiome interacts with the central nervous system and the immune system by neuroendocrine, neurotransmitter, neurotrophic and neuroinflammatory afferent and efferent pathways. There is growing evidence that the gut microbiota influences weight regulation and psychopathology, such as anxiety and depression. This article reviews how the gut-brain interaction may impact the development and course of AN. A "leaky gut", characterized by antigens traversing the intestinal wall, was demonstrated in an animal model of AN, and could underlie the low-grade inflammation and increased risk of autoimmune diseases found in AN. Moreover, starvation has a substantial impact on the gut microbiome, and diets used for re-nutrition based on animal products may support the growth of bacteria capable of triggering inflammation. As there is currently no empirically derived agreement on therapeutic re-nourishment in AN, this review discusses how consideration of gut-brain interactions may be important for treatment regarding the determination of target weight, rapidity of weight gain, refeeding methods and composition of the diet which might all be of importance to improve long-term outcome of one of the most chronic psychiatric disorders of adolescence.

A Review of Research Conducted with Probiotic E. coli Marketed as Symbioflor

This review article summarizes the scientific literature that is currently available about a probiotic E. coli that is known under the name Symbioflor E. coli. The probiotic is marketed for human use and has been subjected to over 20 years of scientific research. As is presented here, the available literature not only contains multiple works to investigate and analyse the probiotic activity of this E. coli, but also describes a variety of other research experiments, dealing with a surprising and interesting range of subjects. By compiling all these works into one review article, more insights into this interesting probiotic E. coli were obtained.

Effect of Probiotics on Central Nervous System Functions in Animals and Humans: A Systematic Review

To systematically review the effects of probiotics on central nervous system function in animals and humans, to summarize effective interventions (species of probiotic, dose, duration), and to analyze the possibility of translating preclinical studies. Literature searches were conducted in Pubmed, Medline, Embase, and the Cochrane Library. Only randomized controlled trials were included. In total, 38 studies were included: 25 in animals and 15 in humans (2 studies were conducted in both). Most studies used Bifidobacterium (eg, B. longum, B. breve, and B. infantis) and Lactobacillus (eg, L. helveticus, and L. rhamnosus), with doses between 10⁹ and 10¹⁰ colony-forming units for 2 weeks in animals and 4 weeks in humans. These probiotics showed efficacy in improving psychiatric disorder-related behaviors including anxiety, depression, autism spectrum disorder (ASD), obsessive-compulsive disorder, and memory abilities, including spatial and non-spatial memory. Because many of the basic science studies showed some efficacy of probiotics on central nervous system function, this background may guide and promote further preclinical and clinical studies. Translating animal studies to human studies has obvious limitations but also suggests possibilities. Here, we provide several suggestions for the translation of animal studies. More experimental designs with both behavioral and neuroimaging measures in healthy volunteers and patients are needed in the future.

British Dietetic Association systematic review and evidence-based practice guidelines for the dietary management of irritable bowel syndrome in adults (2016 update)

BACKGROUND

The first British Dietetic Association (BDA) guidelines for the dietary management of irritable bowel syndrome (IBS) in adults were published in 2012. Subsequently, there has been a wealth of new research. The aim of this work was to systematically review the evidence for the role of diet in the management of IBS and to update the guidelines.

METHODS

Twelve questions relating to diet and IBS were defined based on review of the previous guideline questions, current evidence and clinical practice. Chosen topics were on healthy eating and lifestyle (alcohol, caffeine, spicy food, elimination diets, fat and fluid intakes and dietary habits), milk and dairy, dietary fibre, fermentable carbohydrates, gluten, probiotics and elimination diets/food hypersensitivity. Data sources were CINAHL, Cochrane Register of Controlled Trials, Embase, Medline, Scopus and Web of Science up to October 2015. Studies were assessed independently in duplicate using risk of bias tools specific to each included study based on inclusion and exclusion criteria for each question. National Health and Medical Research Council grading evidence levels were used to develop evidence statements and recommendations, in accordance with Practice-based Evidence in Nutrition Global protocol used by the BDA.

RESULTS

Eighty-six studies were critically appraised to generate 46 evidence statements, 15 clinical recommendations and four research recommendations. The IBS dietary algorithm was simplified to first-line (healthy eating, provided by any healthcare professional) and second-line [low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) to be provided by dietitian] dietary advice.

CONCLUSIONS

These guidelines provide updated comprehensive evidence-based details to achieve the successful dietary management of IBS in adults.

Probiotic lactic acid bacteria - the fledgling cuckoos of the gut?

It is tempting to look at bacteria from our human egocentric point of view and label them as either ‘good’ or ‘bad’. However, a microbial society has its own system of government – ‘microcracy’ – and its own rules of play. Lactic acid bacteria are often referred to as representatives of the good ones, and there is little doubt that those belonging to the normal intestinal flora are beneficial for human health. But we should stop thinking of lactic acid bacteria as always being ‘friendly’ – they may instead behave like fledgling cuckoos.

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disease with a high population prevalence. The disorder can be debilitating in some patients, whereas others may have mild or moderate symptoms. The most important single risk factors are female sex, younger age and preceding gastrointestinal infections. Clinical symptoms of IBS include abdominal pain or discomfort, stool irregularities and bloating, as well as other somatic, visceral and psychiatric comorbidities. Currently, the diagnosis of IBS is based on symptoms and the exclusion of other organic diseases, and therapy includes drug treatment of the predominant symptoms, nutrition and psychotherapy. Although the underlying pathogenesis is far from understood, aetiological factors include increased epithelial hyperpermeability, dysbiosis, inflammation, visceral hypersensitivity, epigenetics and genetics, and altered brain-gut interactions. IBS considerably affects quality of life and imposes a profound burden on patients, physicians and the health-care system. The past decade has seen remarkable progress in our understanding of functional bowel disorders such as IBS that will be summarized in this Primer.