The effect of a multi-strain probiotic on the resistance toward Escherichia coli challenge in a randomized, placebo-controlled, double-blind intervention study

Phenotypic flexibility in nutrition research to quantify human variability: building the bridge to personalised nutrition

Phenotypic flexibility is a methodology that accurately assesses health in terms of mechanistic understanding of the interrelationship of multiple metabolic and physiological processes. This starts from the perspective that a healthy person is better able to cope with changes in environmental stressors that affect homeostasis compared to people with a compromised health state. The term 'phenotypic flexibility' expresses the cumulative ability of overarching physiological processes to return to homeostatic levels after short-term perturbations. The concept of phenotypic flexibility to define biomarkers for nutrition-related health was introduced in 2009 in the area of health optimisation and prevention and delay of non-communicable disease. The core approach consists of the combination of imposing a challenge test to the body followed by time-resolved analysis of multiple biomarkers. This new approach may better facilitate nutritional health research in intervention studies since it may show effects on early derailed physiological markers and the biomarker response can be extended by perturbing the system, thereby making them more sensitive in detecting health effects from food and nutrition. At the same time, interindividual variation can also be extended and compressed by challenge tests, facilitating the bridge to personalised nutrition. This review will overview where the science is in this research arena and what the phenotypic flexibility potential is for the nutrition field.

Orally Ingested Probiotic, Prebiotic, and Synbiotic Interventions as Countermeasures for Gastrointestinal Tract Infections in Nonelderly Adults: A Systematic Review and Meta-Analysis

Meta-analyses have not examined the prophylactic use of orally ingested probiotics, prebiotics, and synbiotics for preventing gastrointestinal tract infections (GTIs) of various etiologies in adult populations, despite evidence that these gut microbiota-targeted interventions can be effective in treating certain GTIs. This systematic review and meta-analysis aimed to estimate the effects of prophylactic use of orally ingested probiotics, prebiotics, and synbiotics on GTI incidence, duration, and severity in nonelderly, nonhospitalized adults. CENTRAL, PubMed, Scopus, and Web of Science were searched through January 2022. English-language, peer-reviewed publications of randomized, placebo-controlled studies testing an orally ingested probiotic, prebiotic, or synbiotic intervention of any dose for ≥1 wk in adults who were not hospitalized, immunosuppressed, or taking antibiotics were included. Results were analyzed using random-effects meta-analyses of intention-to-treat (ITT) and complete case (CC) cohorts. Heterogeneity was explored by subgroup meta-analysis and meta-regression. The risk of bias was assessed using the Cochrane risk-of-bias 2 tool. Seventeen publications reporting 20 studies of probiotics (n = 16), prebiotics (n = 3), and synbiotics (n = 1) were identified (n > 6994 subjects). In CC and ITT analyses, risk of experiencing ≥1 GTI was reduced with probiotics (CC analysis-risk ratio: 0.86; 95% CI: 0.73, 1.01) and prebiotics (risk ratio: 0.80; 95% CI: 0.66, 0.98). No effects on GTI duration or severity were observed. Sources of heterogeneity included the study population and number of probiotic strains administered but were often unexplained, and a high risk of bias was observed for most studies. The specific effects of individual probiotic strains and prebiotic types could not be assessed owing to a lack of confirmatory studies. Findings indicated that both orally ingested probiotics and prebiotics, relative to placebo, demonstrated modest benefit for reducing GTI risk in nonelderly adults. However, results should be interpreted cautiously owing to the low number of studies, high risk of bias, and unexplained heterogeneity that may include probiotic strain-specific or prebiotic-specific effects. This review was registered at PROSPERO as CRD42020200670.

Study protocol for cholera vaccination as a model to measure the inflammatory response in the gut: A case of modulation with a Lactobacillus plantarum K8 lysate

It is crucial for human health that the immune system of the gastrointestinal tract works effectively. Dietary modulation is one of the factors that regulate the immune response in the gut. This study aims to develop a safe human challenge model to study gastrointestinal inflammation and immune function. This study focuses on evaluating gut stimulation induced by the oral cholera vaccine in healthy people. In addition, this paper describes the study design for assessing the efficacy and safety of a probiotic lysate, identifying whether functional ingredients in food can modulate inflammatory response induced by oral cholera vaccine. Forty-six males aged 20 to 50 with healthy bowel habits will be randomly allocated to the placebo or intervention group. Participants will consume 1 capsule of probiotic lysate or placebo twice daily for 6 weeks, take oral cholera vaccines on visit 2 (day 15) and visit 5 (day 29). The level of fecal calprotectin, a marker of gut inflammation, will be the primary outcome. The changes of cholera toxin-specific antibody levels and local/systemic inflammatory responses will be evaluated in blood. The purpose of this study is to evaluate gut stimulation of the oral cholera vaccine and investigate the effect of a probiotic lysate on improving the mild inflammatory response induced by the vaccine or supporting the immune response in healthy subjects. Trial registration: * This trial is registered in the International Clinical Trials Registry Platform of WHO (ICTRP, registration number: KCT0002589).

A Double-Blind, Randomized Intervention Study on the Effect of a Whey Protein Concentrate on E. coli-Induced Diarrhea in a Human Infection Model

Infectious diseases are a major cause of morbidity and mortality worldwide. Nutritional interventions may enhance resistance to infectious diseases or help to reduce clinical symptoms. Here, we investigated whether a whey protein concentrate (WPC) could decrease diarrheagenic Escherichia coli-induced changes in reported stool frequency and gastrointestinal complaints in a double-blind, parallel 4-week intervention study. Subjects were randomly assigned to a whey hydrolysate placebo group, a low-dose WPC group or a high-dose WPC group. After 2 weeks of consumption, subjects (n = 121) were orally infected with a high dose of live but attenuated diarrheagenic E. coli (strain E1392/75-2A; 1E10 colony-forming units). Subjects recorded information on stool consistency and the frequency and severity of symptoms in an online diary. The primary outcome parameters were a change in stool frequency (stools per day) and a change in Gastrointestinal Symptom Rating Scale (GSRS) diarrhea score between the first and second days after infection. Neither dose of the whey protein concentrate in the dietary treatment affected the E. coli-induced increase in stool frequency or GSRS diarrhea score compared to placebo treatment. The composition of the microbiota shifted between the start of the study and after two weeks of consumption of the products, but no differences between the intervention groups were observed, possibly due to dietary guidelines that subjects had to adhere to during the study. In conclusion, consumption of the whey protein concentrate by healthy adults did not reduce diarrhea scores in an E. coli infection model compared to a whey hydrolysate placebo control.

Multi-targeted properties of the probiotic saccharomyces cerevisiae CNCM I-3856 against enterotoxigenic escherichia coli (ETEC) H10407 pathogenesis across human gut models

Enterotoxigenic Escherichia coli (ETEC) is one of the most common causes of acute traveler's diarrhea. Adhesins and enterotoxins constitute the major ETEC virulence traits. With the dramatic increase in antibiotic resistance, probiotics are considered a wholesome alternative to prevent or treat ETEC infections. Here, we examined the antimicrobial properties of the probiotic Saccharomyces cerevisiae CNCM I-3856 against ETEC H10407 pathogenesis upon co-administration in the TNO gastrointestinal Model (TIM-1), simulating the physicochemical and enzymatic conditions of the human upper digestive tract and preventive treatment in the Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME), integrating microbial populations of the ileum and ascending colon. Interindividual variability was assessed by separate M-SHIME experiments with microbiota from six human individuals. The probiotic did not affect ETEC survival along the digestive tract. However, ETEC pathogenicity was significantly reduced: enterotoxin encoding virulence genes were repressed, especially in the TIM-1 system, and a lower enterotoxin production was noted. M-SHIME experiments revealed that 18-days probiotic treatment stimulate the growth of Bifidobacterium and Lactobacillus in different gut regions (mucosal and luminal, ileum and ascending colon) while a stronger metabolic activity was noted in terms of short-chain fatty acids (acetate, propionate, and butyrate) and ethanol production. Moreover, the probiotic pre-treated microbiota displayed a higher robustness in composition following ETEC challenge compared to the control condition. We thus demonstrated the multi-inhibitory properties of the probiotic S. cerevisiae CNCM I-3856 against ETEC in the overall simulated human digestive tract, regardless of the inherent variability across individuals in the M-SHIME.

The Controlled Human Infection Model for Enterotoxigenic Escherichia coli

The controlled human infection model (CHIM) for enterotoxigenic Escherichia coli (ETEC) has been instrumental in defining ETEC as a causative agent of acute watery diarrhea, providing insights into disease pathogenesis and resistance to illness, and enabling preliminary efficacy evaluations for numerous products including vaccines, immunoprophylactics, and drugs. Over a dozen strains have been evaluated to date, with a spectrum of clinical signs and symptoms that appear to replicate the clinical illness seen with naturally occurring ETEC. Recent advancements in the ETEC CHIM have enhanced the characterization of clinical, immunological, and microbiological outcomes. It is anticipated that omics-based technologies applied to ETEC CHIMs will continue to broaden our understanding of host-pathogen interactions and facilitate the development of primary and secondary prevention strategies.

Characterization of the pathophysiological determinants of diarrheagenic Escherichia coli infection using a challenge model in healthy adults

An experimental human challenge model with an attenuated diarrheagenic Escherichia coli (E. coli) strain has been used in food intervention studies aimed to increase resistance to E. coli infection. This study was designed to refine and expand this challenge model. In a double-blind study, healthy male subjects were orally challenged with 1E10 or 5E10 colony-forming units (CFU) of E. coli strain E1392/75-2A. Three weeks later, subjects were rechallenged with 1E10 CFU of E. coli. Before and after both challenges, clinical symptoms and infection- and immune-related biomarkers were analyzed. Subset analysis was performed on clinically high- and low-responders. Regardless of inoculation dose, the first challenge induced clinical symptoms for 2-3 days. In blood, neutrophils, CRP, CXCL10, and CFA/II-specific IgG were induced, and in feces calprotectin and CFA/II-specific IgA. Despite clinical differences between high- and low-responders, infection and immune biomarkers did not differ. The first inoculation induced protection at the second challenge, with a minor clinical response, and no change in biomarkers. The refined study design resulted in a larger dynamic range of symptoms, and identification of biomarkers induced by a challenge with the attenuated E. coli strain E1392/75-2A, which is of value for future intervention studies. Addition of a second inoculation allows to study the protective response induced by a primary infection.Clinicaltrials.gov registration: NCT02541695 (04/09/2015).

Spatial and temporal modulation of enterotoxigenic E. coli H10407 pathogenesis and interplay with microbiota in human gut models

BACKGROUND

Enterotoxigenic Escherichia coli (ETEC) substantially contributes to the burden of diarrheal illnesses in developing countries. With the use of complementary in vitro models of the human digestive environment, TNO gastrointestinal model (TIM-1), and Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME), we provided the first detailed report on the spatial-temporal modulation of ETEC H10407 survival, virulence, and its interplay with gut microbiota. These systems integrate the main physicochemical parameters of the human upper digestion (TIM-1) and simulate the ileum vs ascending colon microbial communities and luminal vs mucosal microenvironments, captured from six fecal donors (M-SHIME).

RESULTS

A loss of ETEC viability was noticed upon gastric digestion, while a growth renewal was found at the end of jejunal and ileal digestion. The remarkable ETEC mucosal attachment helped to maintain luminal concentrations above 6 log₁₀ mL^-1 in the ileum and ascending colon up to 5 days post-infection. Seven ETEC virulence genes were monitored. Most of them were switched on in the stomach and switched off in the TIM-1 ileal effluents and in a late post-infectious stage in the M-SHIME ascending colon. No heat-labile enterotoxin production was measured in the stomach in contrast to the ileum and ascending colon. Using 16S rRNA gene-based amplicon sequencing, ETEC infection modulated the microbial community structure of the ileum mucus and ascending colon lumen.

CONCLUSIONS

This study provides a better understanding of the interplay between ETEC and gastrointestinal cues and may serve to complete knowledge on ETEC pathogenesis and inspire novel prophylactic strategies for diarrheal diseases.

Disease managing capacities and mechanisms of host effects of lactic acid bacteria

Consumption of lactic acid bacteria (LAB) has been suggested to confer health-promoting effects on the host. However, effects of LABs have been reported to be species- and strain-specific and the mechanisms involved are subjects of discussion. Here, the possible mechanisms by which LABs induce antipathogenic, gut barrier enhancing and immune modulating effects in consumers are reviewed. Specific strains for which it has been proven that health is improved by these mechanisms are discussed. However, most strains probably act via several or combinations of mechanisms depending on which effector molecules they express. Current insight is that these effector molecules are either present on the cell wall of LAB or are excreted. These molecules are reviewed as well as the ligand binding receptors in the host. Also postbiotics are discussed. Finally, we provide an overview of the efficacy of LABs in combating infections caused by Helicobacter pylori, Salmonella, Escherichia coli, Streptococcus pneumoniae, and influenza virus, in controlling gut inflammatory diseases, in managing allergic disorders, and in alleviating cancer.

Classical methods and perspectives for manipulating the human gut microbial ecosystem

A healthy Human Gut Microbial Ecosystem (HGME) is a necessary condition for maintaining the orderly function of the whole body. Major alterations in the normal gut microbial composition, activity and functionality (dysbiosis) by an environmental or host-related disruptive event, can compromise metabolic, inflammatory, and neurological processes, causing disorders such as obesity, inflammatory bowel disease, colorectal cancer, and depressive episodes. The restore or the maintaining of the homeostatic balance of Gut Microbiota (GM) populations (eubiosis) is possible through diet, the use of probiotics, prebiotics, antibiotics, and even Fecal Microbiota Transplantation (FMT). Although these "classic methods" represent an effective and accepted way to modulate GM, the complexity of HGME requires new approaches to control it in a more appropriate way. Among the most promising emergent strategies for modulating GM are the use of engineered nanomaterials (metallic nanoparticles (NP), polymeric-NP, quantum dots, micelles, dendrimers, and liposomes); phagotherapy (i.e., phages linked with the CRISPR/Cas9 system), and the use of antimicrobial peptides, non-antibiotic drugs, vaccines, and immunoglobulins. Here we review the current state of development, implications, advantages, disadvantages, and perspectives of the different approaches for manipulating HGME.

Are probiotics and prebiotics effective in the prevention of travellers' diarrhea: A systematic review and meta-analysis

BACKGROUND

Travellers' diarrhea (TD) impacts annually over 20 million tourists, business travellers and military troops on a worldwide basis. Reliance on antibiotic prophylaxis and educational programs has not lead to a significant reduction in TD rates. Previous reviews of probiotics for TD have not accounted for the strain-specificity of probiotic efficacy nor have investigated prebiotics for the prevention of TD.

METHODS

Standard literature databases were searched from 1977 to June 2018 unrestricted by language. Inclusion criteria included: Probiotic, probiotic or symbiotic interventions, randomized, controlled clinical trials (RCTs) and ≥2 RCTs with the same probiotic strain or mixture.

RESULTS

Of 158 screened articles, 12 RCT were included in the systematic review and 6 RCTs (with nine treatment different arms) were included in the meta-analysis. Saccharomyces boulardii CNCM I-745 showed a significant reduction in TD incidence (RR = 0.79, 95% C.I. 0.72-0.87, p < 0.001), while L. rhamnosus GG showed a trend (p = 0.08) and L. acidophilus showed no significant (p = 0.16) reduction of TD.

CONCLUSIONS

The number of trials using probiotics or prebiotics for the prevention of TD continues to be limited in number. Only one of three probiotics showed significant efficacy for the prevention of TD. More research is needed for other probiotics strains and prebiotics to determine if they could also prevent TD.

Probiotics as a tool for disease mitigation in wildlife: insights from food production and medicine

The use of beneficial microbes to improve host attributes, referred to as probiotic therapy, has been increasingly applied to industries, including aquaculture, agriculture, and human medicine, and is emerging in the field of wildlife medicine. However, there is a general lack of shared knowledge regarding successful practices as well as ecological processes that underlie host-microbe interactions. Presently, probiotics are being developed specifically for preventing and treating particular infectious diseases as an alternative to antibiotic treatments and chemotherapy. We review research on probiotics developed for mitigation of infectious disease in the aforementioned industries to gain insight into how probiotics may be effective in reducing wildlife disease risk. We examine the trends of successful in vivo probiotic applications for disease systems and identify common objectives to reduce intestinal pathogens and sexually transmitted and respiratory diseases, inhibit skin pathogens, and serve as environmental prophylaxis to reduce pathogen loads in the environment. We conclude by highlighting the frontier of wildlife probiotics research and identifying knowledge gaps where research is needed.

Probiotics (Lactobacillus gasseri KS-13, Bifidobacterium bifidum G9-1, and Bifidobacterium longum MM-2) improve rhinoconjunctivitis-specific quality of life in individuals with seasonal allergies: a double-blind, placebo-controlled, randomized trial

Background: Rhinoconjunctivitis-specific quality of life is often reduced during seasonal allergies. The Mini Rhinoconjunctivitis Quality of Life Questionnaire (MRQLQ) is a validated tool used to measure quality of life in people experiencing allergies (0 = not troubled to 6 = extremely troubled). Probiotics may improve quality of life during allergy season by increasing the percentage of regulatory T cells (Tregs) and inducing tolerance.Objective: The objective of this study was to determine whether consuming Lactobacillus gasseri KS-13, Bifidobacterium bifidum G9-1, and B. longum MM-2 compared with placebo would result in beneficial effects on MRQLQ scores throughout allergy season in individuals who typically experience seasonal allergies. Secondary outcomes included changes in immune markers as part of a potential mechanism for changes in MRQLQ scores.Design: In this double-blind, placebo-controlled, parallel, randomized clinical trial, 173 participants (mean ± SEM: age 27 ± 1 y) who self-identified as having seasonal allergies received either a probiotic (2 capsules/d, 1.5 billion colony-forming units/capsule) or placebo during spring allergy season for 8 wk. MRQLQ scores were collected weekly throughout the study. Fasting blood samples were taken from a subgroup (placebo, n = 37; probiotic, n = 35) at baseline and week 6 (predicted peak of pollen) to determine serum immunoglobulin (Ig) E concentrations and Treg percentages.Results: The probiotic group reported an improvement in the MRQLQ global score from baseline to pollen peak (-0.68 ± 0.13) when compared with the placebo group (-0.19 ± 0.14; P = 0.0092). Both serum total IgE and the percentage of Tregs increased from baseline to week 6, but changes were not different between groups.Conclusions: This combination probiotic improved rhinoconjunctivitis-specific quality of life during allergy season for healthy individuals with self-reported seasonal allergies; however, the associated mechanism is still unclear. This trial was registered at clinicaltrials.gov as NCT02349711.

Can probiotics modulate human disease by impacting intestinal barrier function?

Intestinal barrier integrity is a prerequisite for homeostasis of mucosal function, which is balanced to maximise absorptive capacity, while maintaining efficient defensive reactions against chemical and microbial challenges. Evidence is mounting that disruption of epithelial barrier integrity is one of the major aetiological factors associated with several gastrointestinal diseases, including infection by pathogens, obesity and diabetes, necrotising enterocolitis, irritable bowel syndrome and inflammatory bowel disease. The notion that specific probiotic bacterial strains can affect barrier integrity fuelled research in which in vitro cell lines, animal models and clinical trials are used to assess whether probiotics can revert the diseased state back to homeostasis and health. This review catalogues and categorises the lines of evidence available in literature for the role of probiotics in epithelial integrity and, consequently, their beneficial effect for the reduction of gastrointestinal disease symptoms.

Foodborne enterotoxigenic Escherichia coli: from gut pathogenesis to new preventive strategies involving probiotics

Enterotoxigenic Escherichia coli (ETEC) are a major cause of traveler's diarrhea and infant mortality in developing countries. Given the rise of antibiotic resistance worldwide, there is an urgent need for the development of new preventive strategies. Among them, a promising approach is the use of probiotics. Although many studies, mostly performed under piglet digestive conditions, have shown the beneficial effects of probiotics on ETEC by interfering with their survival, virulence or adhesion to mucosa, underlying mechanisms remain unclear. This review describes ETEC pathogenesis, its modulation by human gastrointestinal cues as well as novel preventive strategies with a particular emphasis on probiotics. The potential of in vitro models simulating human digestion in elucidating probiotic mode of action will be discussed.

Dietary Milk-Fat-Globule Membrane Affects Resistance to Diarrheagenic Escherichia coli in Healthy Adults in a Randomized, Placebo-Controlled, Double-Blind Study

BACKGROUND

The milk-fat-globule membrane (MFGM) contains phospholipids and membrane glycoproteins that have been shown to affect pathogen colonization and gut barrier integrity.

OBJECTIVE

In the present study, we determined whether commercial heat-treated MFGM can increase resistance to diarrheagenic Escherichia coli.

METHODS

A randomized, placebo-controlled, double-blind, 4-wk parallel-intervention study was conducted in healthy adults. Participants were randomly assigned to a milk protein concentrate rich in MFGM [10 g Lacprodan PL-20 (Arla Foods Ingredients Group P/S), twice daily; n = 30; MFGM group) or a control [10 g Miprodan 30 (sodium caseinate), twice daily; n = 28]. After 2 wk, participants were orally challenged with live, attenuated diarrheagenic E. coli (10(10) colony-forming units). Primary outcomes were infection-induced diarrhea and fecal diarrheagenic E. coli excretion. Secondary outcomes were gastrointestinal symptoms [Gastrointestinal Symptom Rating Scale (GSRS)], stool frequency, and stool consistency (Bristol Stool Scale).

RESULTS

Diarrheagenic E. coli resulted in increased fecal output, lower relative fecal dry weight, increased fecal E. coli numbers, and an increase in stool frequency and gastrointestinal complaints at day 1 after challenge. MFGM significantly decreased the E. coli-induced changes in reported stool frequency (1.1 ± 0.1 stools/d in the MFGM group; 1.6 ± 0.2 stools/d in the control group; P = 0.04) and gastrointestinal complaints at day 2 (1.1 ± 0.5 and 2.5 ± 0.6 GSRS scores in the MFGM and control groups, respectively; P = 0.05). MFGM did not affect fecal wet weight and E. coli excretion at day 2 after challenge.

CONCLUSIONS

The attenuated diarrheagenic E. coli strain transiently induced mild symptoms of a food-borne infection, with complete recovery of reported clinical symptoms within 2 d. The present diarrheagenic E. coli challenge trial conducted in healthy adults indicates that a milk concentrate rich in natural, bioactive phospho- and sphingolipids from the MFGM may improve in vivo resistance to diarrheagenic E. coli. This trial was registered at clinicaltrials.gov as NCT01800396.