Probiotics in functional intestinal disorders and IBS: proof of action and dissecting the multiple mechanisms

Themes, communities and influencers of online probiotics chatter: A retrospective analysis from 2009-2017

We build on recent examinations questioning the quality of online information about probiotic products by studying the themes of content, detecting virtual communities and identifying key influencers in social media using data science techniques. We conducted topic modelling (n = 36,715 tweets) and longitudinal social network analysis (n = 17,834 tweets) of probiotic chatter on Twitter from 2009-17. We used Latent Dirichlet Allocation (LDA) to build the topic models and network analysis tool Gephi for building yearly graphs. We identified the top 10 topics of probiotics-related communication on Twitter and a constant rise in communication activity. However the number of communities grew consistently to peak in 2014 before dipping and levelling off by 2017. While several probiotics industry actors appeared and disappeared during this period, the influence of one specific actor rose from a hub initially to an authority in the latter years. With multi-brand advertising and probiotics promotions mostly occupying the Twitter chatter, scientists, journalists, or policymakers exerted minimal influence in these communities. Consistent with previous research, we find that probiotics-related content on social media veers towards promotions and benefits. Probiotic industry actors maintain consistent presence on Twitter while transitioning from hubs to authorities over time; scientific entities assume an authoritative role without much engagement. The involvement of scientific, journalistic or regulatory stakeholders will help create a balanced informational environment surrounding probiotic products.

Effects of Akkermansia muciniphila and Faecalibacterium prausnitzii on serotonin transporter expression in intestinal epithelial cells

PURPOSE

The highest level of peripheral serotonin in the body can be found in the gastrointestinal (GI) tract as its reservoir. There is complete interaction between human gastrointestinal microbiota and serotonin system. Serotonin in the GI is transferred by serotonin transporters (SERTs), which play a crucial role in the bioavailability of serotonin in the GI. SERT impairment is associated with the pathology of GI disorders. It is known that intestinal microbiota can regulate the SERT function. Therefore, it may be useful to regulate of SERT expression by modulation of microbiota and improvement of intestinal motility and GI sensation. In this study, we aimed to evaluate the effects of two next-generation probiotics, including Akkermansia muciniphila and Faecalibacterium prausnitzii, and their supernatants on SERT gene expression in human epithelial colorectal adenocarcinoma cells (Caco-2).

METHODS

The Caco-2 cells were treated with multiplicity of infection (MOI) ratio of 100 of A. muciniphila and F. prausnitzii, as well as their supernatants. After 24 h, SERT gene expression was examined by quantitative real-time polymerase chain reaction (qRT-PCR) assay.

RESULTS

A. muciniphila up-regulated the SERT mRNA level by 3.01 folds, compared to the control group. F. prausnitzii, similar to A. muciniphila, increased the expression of SERT gene in Caco-2 cells by 3.43 folds (P < 0.001). Moreover, the supernatants of A. muciniphila and F. prausnitzii significantly up-regulated the expression of SERT gene in the cell line by 2.4 and 5.7 folds, respectively, compared to the control group (P < 0.001).

CONCLUSIONS

The present results showed that A. muciniphila and F. prausnitzii, as well as their supernatants, increased the expression of SERT gene in Caco-2 cells. Therefore, they might be helpful in the microbiota-modulating treatment of inflammatory bowel diseases.

Effects of vasoactive drugs on hepatic and intestinal circulation and intestinal barrier in patients with septic shock

In this study, 60 patients with septic shock were selected over the course of 1 year, and the effects of dopamine and norepinephrine combined with dobutamine on hepatic and intestinal circulation and intestinal barrier in patients with septic shock were studied by comparison between the control group and the experimental group. All patients received mechanical ventilation to maintain breathing at 14 to 20 times/min. The experimental group was treated with vascular active drugs after adequate rehydration, and the control group only received adequate rehydration. There were extremely significant differences (p<0.01) in the total effective rate of each group. There were significant differences in the hemodynamic indexes in each group (p<0.05). There was a significant difference in total 24-hour bile output (p<0.01). There were significant differences in liver function and blood lipid values in patients (p<0.01). There were significant differences in the repair of epithelial injury at 0 hour, 48 hours and 96 hours (p<0.01). There were significant differences in the transmembrane resistance of monolayer cells (p<0.01). The expression differences of three proteins ZO-1, occludin and β-actin were also significant, among which the three proteins in the control group were weak, while those in groups A and B were strong. The expression of tight junction protein in monolayer cells was weakly positive in expression and strong in other proteins. In conclusion, vasoactive drugs had significant effects on hepatic and intestinal circulation and intestinal barrier in patients with septic shock.

Systematic review and meta-analysis: the effects of fermented milk with Bifidobacterium lactis CNCM I-2494 and lactic acid bacteria on gastrointestinal discomfort in the general adult population

BACKGROUND

It has been suggested that probiotics may improve gastrointestinal discomfort. Not all probiotics exhibit the same effects and consequently meta-analyses on probiotics should be confined to well-defined strains or strain combinations. The aim of this study was to evaluate the effectiveness of a probiotic fermented milk (PFM) that includes Bifidobacterium lactis (B. lactis) CNCM I-2494 and lactic acid bacteria on gastrointestinal discomfort in the general adult population.

METHODS

Double-blind randomized controlled trials in the general adult population comparing PFM with a control dairy product for at least 4 weeks were searched from multiple literature databases (up to February 2015). Meta-analyses using random-effects models, with individual participant data were undertaken to calculate an odds ratio (OR) or standard mean difference (SMD), with a 95% confidence interval (CI).

RESULTS

The search strategy identified 12,439 documents. Overall, three trials with a total of 598 adults (female = 96.5%) met the inclusion criteria. Consumption of the PFM product was associated with a significant improvement in overall gastrointestinal discomfort compared with the control product (OR = 1.48; 95% CI 1.07-2.05), with a number needed to treat (NNT) of 10.24 (95% CI 5.64-55.93). PFM was also superior to the control in reducing digestive symptoms, as measured using a composite score (SMD = -0.21; 95% CI -0.37 to -0.05). Sensitivity analyses produced similar results, and the heterogeneity between studies was minimal.

CONCLUSIONS

This meta-analysis shows that the consumption of PFM with B. lactis CNCM I-2494 and lactic acid bacteria is associated with a modest but consistent and significant improvement of outcomes related to gastrointestinal discomfort in healthy adults.

A future perspective on neurodegenerative diseases: nasopharyngeal and gut microbiota

Neurodegenerative diseases are considered a serious life-threatening issue regardless of age. Resulting nerve damage progressively affects important activities, such as movement, coordination, balance, breathing, speech and the functioning of vital organs. Reports on the subject have concluded that neurodegenerative disease can be caused by mutations of susceptible genes, alcohol consumption, toxins, chemicals and other unknown environmental factors. Although several diagnostic techniques can be used to determine aetiologies, the process is difficult and often fails. Research shows that nasopharyngeal and gut microbiota play important roles in brain to spinal cord coordination. However, no conclusive epidemiologic evidence is available on the roles played by respiratory and gut microbiota in the development of neurodegenerative diseases. Thus, understanding the connection between respiratory and gut microbiota and the nervous system could provide information on causal links. The present review describes future perspectives on the role played by nasopharyngeal and gut microbiota in the development of neurodegenerative diseases.

Lactobacillus rhamnosus GG supernatant upregulates serotonin transporter expression in intestinal epithelial cells and mice intestinal tissues

BACKGROUND

The role that probiotics play in relieving irritable bowel syndrome (IBS) has been demonstrated; however, the mechanism by which IBS is affected remains unclear. In this study, serotonin transporter (SERT) mRNA and serotonin transporter protein (SERT-P) levels in HT-29, Caco-2 cells, and mice intestinal tissues were examined after treatment with Lactobacillus rhamnosus GG supernatant (LGG-s).

METHODS

HT-29 and Caco-2 cells were treated with different concentrations of LGG-s for 12 and 24 h and C57BL/6 mice received supplements of different concentrations for 4 weeks. SERT mRNA and SERT-P levels were detected by real-time PCR and Western blotting.

KEY RESULTS

SERT mRNA and SERT-P levels in HT-29 and Caco-2 cells were higher than those in the control 24 h after treatment. Undiluted LGG-s upregulated SERT mRNA levels by 9.4-fold in the first week, which dropped in the second week. The double-diluted LGG-s upregulated SERT mRNA by 2.07-fold in the first week; levels dropped to 1.75-fold within the second week and under base expression levels by the third week, while they again climbed to 1.56-fold in the fourth week. The triple-diluted LGG-s could not upregulate SERT mRNA expression until the end of the fourth week. The SERT-P levels in the double-diluted LGG-s group were higher than that in the control but fluctuated with time. SERT-P levels in the triple-diluted LGG-s were higher than that in the control in the last 2 weeks and increased with time.

CONCLUSIONS & INFERENCES

LGG-s can upregulate SERT mRNA and SERT-P levels in intestinal epithelial cells and mice intestinal tissues.

A randomized, double-blind, controlled study and pooled analysis of two identical trials of fermented milk containing probiotic Bifidobacterium lactis CNCM I-2494 in healthy women reporting minor digestive symptoms

BACKGROUND

The probiotic fermented milk (PFM) containing Bifidobacterium lactis CNCM I-2494 improved gastrointestinal (GI) well-being and digestive symptoms in a previous trial involving women reporting minor digestive symptoms. Our objective is to confirm these findings in a second study and in a pooled analysis of both studies.

METHODS

In this double-blind, controlled, parallel design study, subjects without diagnosed GI disorders consumed PFM or control dairy product daily for 4 weeks. Endpoints comprised weekly assessment of GI well-being (primary endpoint), rate of responders and digestive symptoms. Data were analyzed on full analysis set population (n = 324) and on the pooled data of randomized subjects of this study with those of the first study (n = 538).

KEY RESULTS

In this second study, no significant difference was observed in the percentage of women reporting an improvement in GI well-being [OR = 1.20 (95% CI 0.87, 1.66)] and rate of responders [OR = 1.38 (95% CI 0.89, 2.14)]. Composite score of digestive symptoms was significantly (P < 0.05) reduced in PFM when compared to the control group [LSmean = -0.42 (95% CI -0.81, -0.03)]. In the pooled analysis, significant differences were observed in favor of PFM group for all endpoints: percentage of women with improved GI well-being [OR = 1.36 (95% CI 1.07, 1.73)], rate of responders [OR = 1.53 (95% CI 1.09, 2.16)] and composite score of digestive symptoms [LSmean = -0.48 (95% CI -0.80, -0.16)].

CONCLUSIONS & INFERENCES

This second study did not confirm improvement on the primary endpoint. However, a pooled analysis of the two trials showed improvement in GI well-being and digestive symptoms in women reporting minor digestive symptoms.

IBS-associated phylogenetic unbalances of the intestinal microbiota are not reverted by probiotic supplementation

IBS is a prevalent functional gastrointestinal disorder, in which the microbiota has been demonstrated to play a role. An increasing number of studies have suggested how probiotics may alleviate IBS symptoms and several mechanisms of action have been proposed.   In the present study we characterized the intestinal microbiota of 19 subjects suffering from diagnosed IBS using a fully validated High Taxonomic Fingerprint Microbiota Array (HTF-Microbi.Array). We demonstrated that the IBS microbiota is different from that of healthy individuals due to an unbalance in a number of commensal species, with an increase in relative abundance of lactobacilli, B. cereus and B. clausii, bifidobacteria, Clostridium cluster IX and E. rectale, and a decrease in abundance of Bacteroides/Prevotella group and Veillonella genus. Additionally, we demonstrated that some bacterial groups of the human intestinal microbiota, recently defined as pathobionts, are increased in concentration in the IBS microbiota. Furthermore, we aimed at investigating if the daily administration of a novel probiotic yogurt containing B. animalis subsp lactis Bb12 and K. marxianus B0399, recently demonstrated to have beneficial effects in the management of IBS symptoms, could impact on the biostructure of IBS microbiota, modulating its composition to counteract putative dysbiosis found in IBS subjects. Notably, we demonstrated that the beneficial effects associated to the probiotic preparation are not related to significant modifications in the composition of the human intestinal microbiota.

Microbiota, innate immune system, and gastrointestinal muscle: ongoing studies

AIM

To test the activities of culture-extracted or commercially available toll-like receptors (TLRs) ligands to establish their direct impact on target gastrointestinal motor cells.

METHODS

Short-term and long-term effects of Shigella flexneri M90T and Escherichia coli K-2 strains-extracted lipopolysaccharides (LPS), commercially highly purified LPS (E. coli O111:B4 and EH100), and Pam2CSK4 and Pam3CSK4, which bind TLR2/6 and TLR1/2 heterodimers, respectively, have been assessed on pure primary cultures of colonic human smooth muscle cells (HSMC).

RESULTS

Pathogenic Shigella-LPS and nonpathogenic E. coli K-2-LPS induced a time-dependent decrease of resting cell length and acetylcholine-induced contraction, with both alterations occurring rapidly and being more pronounced in response to the former. However, their effects differed, prolonging HSMC exposure with Shigella-LPS effects maintained throughout the 4 hours of observation compared with E. coli K-2-LPS, which disappeared after 60 minutes of incubation. Similar differences in magnitude and time dependency of myogenic effects were observed between pure TLR4 and TLR2/1 or TLR2/6 ligands. The specific activation of TLR4 with LPS from pathogen or nonpathogen E. coli, O111:B4 and EH100, respectively, induced smooth muscle alterations that progressively increased, prolonging incubation, whereas TLR2 ligands induced short-term alterations, of a lesser magnitude, which decreased over time. The real-time polymerase chain reaction analysis showed that HSMC express mRNA for TLR1, 2, 4, and 6, substantiating a direct effect of TLR ligands on human colonic smooth muscle.

CONCLUSIONS

This study highlights that bacterial products can directly affect gastrointestinal motility and that TLRs subtypes may differ in their cellular activity.

Probiotics and irritable bowel syndrome

Background

Irritable bowel syndrome (IBS) is a major cause of abdominal discomfort and gut dysfunction worldwide. It is a poorly understood functional gastrointestinal disorder for which no effective medication is available. It is a benign condition, but its social and economic burden is significant. The symptoms consist of abdominal pain, bloating, flatulence, and irregular bowel movements. Alterations in the intestinal microbiota and mucosal inflammation may contribute to the development of IBS and probiotics could thus relieve the symptoms. This review gives an overview on the existing data on the effects of probiotics on the gastrointestinal symptoms of IBS.

Methods

A PUBMED search was made to review the relevant literature, and additional studies were obtained from the references of the selected articles.

Results

Clinical trials suggest that certain probiotics or combinations of bacteria have beneficial effects on the IBS symptoms. However the heterogeneity of studies, e.g. suboptimal study design, inadequate number of subjects, different doses and vehicles, inadequate length, make it difficult to compare the differences between probiotics and the effect may be strain-specific.

Conclusions

Though evidence is very promising, no general recommendations on the use of probiotics in IBS can be given yet. Further clinical trials and data on the mechanisms of action are needed. Probiotics are considered safe and if future scientific data is able to substantiate their efficacy in IBS, they certainly could be a treatment option in relieving the symptoms in IBS.

Review article: probiotics for the treatment of irritable bowel syndrome--focus on lactic acid bacteria

BACKGROUND

Irritable bowel syndrome (IBS) is a poorly understood, yet highly prevalent functional gastrointestinal disorder (FGID). The withdrawal, due to adverse events, of a number of pharmacological agents that were approved for the treatment of IBS has left a therapeutic vacuum for patients suffering from the disorder.

AIM

To review, summarise and critically evaluate current knowledge of lactic acid bacteria (LAB) used to treat IBS.

METHODS

We assessed a comprehensive range of relevant literature from Pubmed, Medline and online sources based on our definition of LAB which included both typical and atypical species, covering Lactobacilli, Bifidobacteria, Enterococci, Streptococci and Bacilli.

RESULTS

Of the 42 trials evaluated examining the efficacy of LAB in IBS, 34 reported beneficial effects in at least one of the endpoints or symptoms examined, albeit with tremendous variation in both the magnitude of effect and the choice of outcome under consideration. However, numerous concerns have been expressed over deficits of trial design and execution relating to strain selection, optimum dosage, mode of action, safety and long-term tolerability in a disorder that can persist throughout the lifetime of affected individuals.

CONCLUSIONS

Progress in the field will require an improved understanding of how the microbiota impacts on health and disease, adequately powered long-term multicentre trials and the embracing of bench to bedside approaches. Recent incremental advances suggest these areas are being addressed and that the future holds much promise for the use of lactic acid bacteria in the treatment of irritable bowel syndrome.

Diagnosis, comorbidities, and management of irritable bowel syndrome in patients in a large health maintenance organization

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) imposes significant clinical and economic burdens. We aimed to characterize practice patterns for patients with IBS in a large health maintenance organization, analyzing point of diagnosis, testing, comorbidities, and treatment.

METHODS

Members of Kaiser Permanente Northern California who were diagnosed with IBS were matched to controls by age, sex, and period of enrollment. We compared rates of testing, comorbidities, and interventions.

RESULTS

From 1995-2005, IBS was diagnosed in 141,295 patients (mean age, 46 years; standard deviation, 17 years; 74% female). Internists made 68% of diagnoses, gastroenterologists 13%, and others 19%. Lower endoscopy did not usually precede IBS diagnosis. Patients with IBS were more likely than controls to have blood, stool, endoscopic, and radiologic tests and to undergo abdominal or pelvic operations (odds ratios, 1.5-10.7; all P < .0001). Only 2.7% were tested for celiac disease, and only 1.8% were eventually diagnosed with inflammatory bowel disease. Chronic pain syndromes, anxiety, and depression were more common among IBS patients than among controls (odds ratios, 2.7-4.6; all P < .0001). Many patients with IBS were treated with anxiolytics (61%) and antidepressants (55%). Endoscopic and radiologic testing was most strongly associated with having IBS diagnosed by a gastroenterologist. Psychotropic medication use was most strongly associated with female sex.

CONCLUSIONS

In a large, managed care cohort, most diagnoses of IBS were made by generalists, often without endoscopic evaluation. Patients with IBS had consistently higher rates of testing, chronic pain syndromes, psychiatric comorbidity, and operations than controls. Most patients with IBS were treated with psychiatric medications.

Brain-gut-microbe communication in health and disease

Bidirectional signalling between the gastrointestinal tract and the brain is regulated at neural, hormonal, and immunological levels. This construct is known as the brain–gut axis and is vital for maintaining homeostasis. Bacterial colonization of the intestine plays a major role in the post-natal development and maturation of the immune and endocrine systems. These processes are key factors underpinning central nervous system (CNS) signaling. Recent research advances have seen a tremendous improvement in our understanding of the scale, diversity, and importance of the gut microbiome. This has been reflected in the form of a revised nomenclature to the more inclusive brain–gut–enteric microbiota axis and a sustained research effort to establish how communication along this axis contributes to both normal and pathological conditions. In this review, we will briefly discuss the critical components of this axis and the methodological challenges that have been presented in attempts to define what constitutes a normal microbiota and chart its temporal development. Emphasis is placed on the new research narrative that confirms the critical influence of the microbiota on mood and behavior. Mechanistic insights are provided with examples of both neural and humoral routes through which these effects can be mediated. The evidence supporting a role for the enteric flora in brain–gut axis disorders is explored with the spotlight on the clinical relevance for irritable bowel syndrome, a stress-related functional gastrointestinal disorder. We also critically evaluate the therapeutic opportunities arising from this research and consider in particular whether targeting the microbiome might represent a valid strategy for the management of CNS disorders and ponder the pitfalls inherent in such an approach. Despite the considerable challenges that lie ahead, this is an exciting area of research and one that is destined to remain the center of focus for some time to come.

Randomised clinical trial: Bifidobacterium bifidum MIMBb75 significantly alleviates irritable bowel syndrome and improves quality of life--a double-blind, placebo-controlled study

BACKGROUND

Recent research suggests that an imbalance of the intestinal microbiota and a dysfunctional intestinal barrier might trigger irritable bowel syndrome (IBS). As probiotics have been reported to restore the intestinal microbiota and the gut barrier, the therapeutic potential of probiotics within IBS became of strong interest.

AIM

To assess the efficacy of Bifidobacterium bifidum MIMBb75 in IBS.

METHODS

A total of 122 patients were randomised to receive either placebo (N=62) or MIMBb75 (N=60) once a day for 4 weeks. The severity of IBS symptoms was recorded daily on a 7-point Likert scale.

RESULTS

MIMBb75 significantly reduced the global assessment of IBS symptoms by -0.88 points (95% CI: -1.07; -0.69) when compared with only -0.16 (95% CI: -0.32; 0.00) points in the placebo group (P<0.0001). MIMBb75 also significantly improved the IBS symptoms pain/discomfort, distension/bloating, urgency and digestive disorder. The evaluation of the SF12 sum scores showed a significant gain in quality of life within the bifidobacteria group. Furthermore, adequate relief was reported by 47% of the patients in the bifidobacteria and only by 11% of the patients in the placebo group (P<0.0001). Overall responder rates were 57% in the bifidobacteria group but only 21% in the placebo group (P=0.0001). MIMBb75 was well tolerated and adverse events were not different from placebo.

CONCLUSIONS

Bifidobacterium bifidum MIMBb75 effectively alleviates global IBS and improves IBS symptoms simultaneously with an improvement of quality of life. Considering the high efficacy of MIMBb75 in IBS along with the good side-effect profile, MIMBb75 is a promising candidate for IBS therapy.