Use of a fermented dairy probiotic drink containing Lactobacillus casei (DN-114 001) to decrease the rate of illness in kids: the DRINK study. A patient-oriented, double-blind, cluster-randomized, placebo-controlled, clinical trial

Effects of Bifidobacterium animalis subsp. lactis BB-12 and yogurt on mice during oral antibiotic administration

Probiotics have the potential to prevent disruptions to normal gastrointestinal function caused by oral antibiotic use. In this study, we examined the capacity of Bifidobacterium animalis subspecies lactis BB-12 (BB-12) and yogurt, separately and combined, to mitigate the effects of the antibiotic amoxicillin-clavulanate (AMC) on the gut microbiota and metabolomes of C57BL/6 J mice. Male and female mice were administered either BB-12, yogurt, BB-12 in yogurt, or saline for 10 days concurrent with the inclusion of AMC in the drinking water. Male mice exposed to AMC exhibited significant reductions (p<0.05) in body weight over the course of the study compared to sham (no AMC) controls whereas no such effects were observed for female mice. AMC administration resulted in rapid alterations to the intestinal microbiota in both sexes irrespective of BB-12 or yogurt treatment, including significant (p<0.05) losses in bacterial cell numbers and changes in microbial alpha-diversity and beta-diversity in the feces and cecal contents. The effects of AMC on the gut microbiota were observed within one day of administration and the bacterial contents continued to change over time, showing a succession marked by rapid reductions in Muribaculaceae and Lachnospiraceae and temporal increases in proportions of Acholeplasmataceae (day 1) and Streptococcaceae and Leuconostocaceae (day 5). By day 10 of AMC intake, high proportions of Gammaproteobacteria assigned as Erwiniaceae or Enterobacteriaceae (average of 63 %), were contained in the stools and were similarly enriched in the cecum. The cecal contents of mice given AMC harbored significantly reduced concentrations of (branched) short-chain fatty acids (SCFA), aspartate, and other compounds, whereas numerous metabolites, including formate, lactate, and several amino acids and amino acid derivatives were significantly enriched. Despite the extensive impact of AMC, starting at day 7 of the study, the body weights of male mice given yogurt or BB-12 (in saline) with AMC were similar to the healthy controls. BB-12 (in saline) and yogurt intake was associated with increased Streptococcaceae and both yogurt and BB-12 resulted in lower proportions of Erwiniaceae in the fecal and cecal contents. The cecal contents of mice fed BB-12 in yogurt contained levels of formate, glycine, and glutamine that were equivalent to the sham controls. These findings highlight the potential of BB-12 and yogurt to mitigate antibiotic-induced gut dysbiosis.

The Influence of Probiotic Lactobacilli on COVID-19 and the Microbiota

This comprehensive review explores the potential of using lactobacilli as a probiotic in the management of COVID-19. Our findings suggest that lactobacilli show promise in reducing the risk of death, gastrointestinal and overall symptoms, and respiratory failure, as well as in lowering cytokines and inflammatory markers associated with the disease. The molecular mechanisms by which lactobacilli protect against COVID-19 and other viral infections may be related to the reduction in inflammation, modulation of the immune response, and direct interaction with viruses to produce antiviral substances. However, the selected studies demonstrate the presence of mixed findings for various clinical, biochemical, hematological, and immunological parameters, which may be attributed to methodological differences among studies. We highlight the importance of clearly describing randomization processes to minimize bias and caution against small sample sizes and inappropriate statistical tests that could lead to errors. This review offers valuable insights into the therapeutic potential of lactobacilli in the context of COVID-19 and identifies avenues for further research and applications. These findings hold promise for the development of novel approaches to managing COVID-19 and warrant further investigation into the potential benefits of lactobacilli in combating the disease.

Recent advances in antimicrobial peptide-based therapy

Antimicrobial peptides (AMPs) are a group of polypeptide chains that have the property to target and kill a myriad of microbial organisms including viruses, bacteria, protists, etc. The first discovered AMP was named gramicidin, an extract of aerobic soil bacteria. Further studies discovered that these peptides are present not only in prokaryotes but in eukaryotes as well. They play a vital role in human innate immunity and wound repair. Consequently, they have maintained a high level of intrigue among scientists in the field of immunology, especially so with the rise of antibiotic-resistant pathogens decreasing the reliability of antibiotics in healthcare. While AMPs have promising potential to substitute for common antibiotics, their use as effective replacements is barred by certain limitations. First, they have the potential to be cytotoxic to human cells. Second, they are unstable in the blood due to action by various proteolytic agents and ions that cause their degradation. This review provides an overview of the mechanism of AMPs, their limitations, and developments in recent years that provide techniques to overcome those limitations. We also discuss the advantages and drawbacks of AMPs as a replacement for antibiotics as compared to other alternatives such as synthetically modified bacteriophages, traditional medicine, and probiotics.

The effect of bovine dairy products and their components on the incidence and natural history of infection: a systematic literature review

BACKGROUND

Dairy products and their components may impact immune function, although the current evidence base has some research gaps. As part of a larger systematic literature review of dairy products/components (including probiotics, dairy proteins, and dairy fats) and immune function, we identified the available epidemiologic research on the impact of dairy products/components on incidence and natural history of infectious diseases.

METHODS

PubMed and Embase databases were systematically searched through May 2022 to identify eligible studies using pre-defined Population, Intervention, Comparator, Outcomes, and Study design criteria. Herein, we focused on describing the impacts of dairy product/component on infectious disease outcomes, including the effect on leukocyte and cytokine response in humans. Risk of bias assessment was performed using the Academy of Nutrition and Dietetics Quality Criteria Checklist. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed.

RESULTS

Among 9,832 studies identified from the larger literature search, 133 relevant publications from 128 studies reported on dairy product/component and infectious disease outcomes. Few studies are available on the impact of non-fermented milk and traditional yogurt on infectious disease. Evidence was identified to suggest milk and yogurt drinks fermented with Lactobacillus strains reduce the risk and burden of common infectious diseases (CIDs), although the findings are mixed and difficult to reconcile due to heterogenous study populations, bacterial strains, and study methods. Few studies are available on the impact of dairy products/components on the natural history of infection, with the available findings indicating probiotics may both improve gastrointestinal symptoms among HIV-infected persons and help eradicate and alleviate the symptoms of Heliobacter (H.) pylori. The available evidence also suggests lactoferrin may reduce the virological burden of COVID-19 and hepatitis C virus. No consistent changes in leukocytes or cytokine production were observed for any type of dairy product or their components, but probiotics appeared to enhance natural killer cell levels/activity and the phagocytic process.

CONCLUSIONS

Dairy products, particularly those with added probiotics, may represent an easily accessible nutritional intervention to prevent and improve the course of infectious diseases. This review highlights the need for additional research in this potentially impactful area.

PROSPERO REGISTRATION

CRD42022333780.

The impact of probiotics and vitamin C on the prevention of upper respiratory tract symptoms in two preschool children cohorts

BACKGROUND/OBJECTIVES

The efficacy of Lab4 probiotic and vitamin C combination on the prevention of upper respiratory tract infections (URTIs) was investigated in two studies with children. Our objective was to pool dataset of 57 preschool children from the PROCHILD study (ISRCTN28722693) and the dataset of 50 preschool matched cohort from the PROCHILD-2 study (ISRCTN26587549) to evaluate the impact of probiotic/vitamin C combination on the prevention of upper respiratory tract symptoms and provide a more robust assessment of effect using detailed individual level data.

SUBJECTS/METHODS

The children were supplemented daily for 6 months with either the multistrain probiotic (1.25×1010 cfu/tablet consisting of two strains of Lactobacillus acidophilus CUL21 and CUL60, Bifidobacterium bifidum CUL20 and Bifidobacterium animalis subsp. lactis CUL34) plus 50 mg vitamin C or a placebo.

RESULTS

In the pooled analysis of the individual participant data (per protocol population), significant reductions were observed for the incidence (-25%; 95% confidence interval [CI], 0.66, 0.85; P < 0.0001) and duration (-14.9 days; 95% CI, -24.8, -5.1; P = 0.0030) of typical URTI symptoms in the active group compared with the placebo. The incidence rates of absenteeism from preschool (IR ratio, 0.75; 95% CI, 0.66, 0.86; P < 0.0001), paediatric visits (IR ratio, 0.56; 95% CI, 0.47; 0.68; P < 0.0001) and antibiotic usage (IR ratio, 0.53; 95% CI, 0.39, 0.71; P < 0.0001) were also significantly reduced.

CONCLUSION

The pooled analysis findings of comparable preschool cohorts from two studies indicate that the supplementation with probiotic and vitamin C combination is beneficial in the prevention and management of URTI symptoms.

Lactobacilli in COVID-19: A Systematic Review Based on Next-Generation Sequencing Studies

The global pandemic was caused by the SARS-CoV-2 virus, known as COVID-19, which primarily affects the respiratory and intestinal systems and impacts the microbial communities of patients. This systematic review involved a comprehensive search across the major literature databases to explore the relationship between lactobacilli and COVID-19. Our emphasis was on investigations employing NGS technologies to explore this connection. Our analysis of nine selected studies revealed that lactobacilli have a reduced abundance in the disease and an association with disease severity. The protective mechanisms of lactobacilli in COVID-19 and other viral infections are likely to be multifaceted, involving complex interactions between the microbiota, the host immune system, and the virus itself. Moreover, upon closely examining the NGS methodologies and associated statistical analyses in each research study, we have noted concerns regarding the approach used to delineate the varying abundance of lactobacilli, which involves potential biases and the exclusion of pertinent data elements. These findings provide new insight into the relationship between COVID-19 and lactobacilli, highlighting the potential for microbiota modulation in COVID-19 treatment.

Overview of anti-viral effects of probiotics via immune cells in pre-, mid- and post-SARS-CoV2 era

The COVID-19 outbreak has caused significant global changes and increased public awareness of SARS-CoV-2. Substantial progress in developing vaccines, enhancing sanitation practices, and implementing various measures to combat the virus, including the utilization of probiotics has been made. This comprehensive review examined the medical impact of clinically proven probiotics on infectious diseases, considering three crucial time periods: before (pre-), during (mid-), and after (post-) COVID-19 pandemic era. This review also showed a perspective on the use of probiotics to stimulate the innate immune system and prevent infectious diseases. In pre-COVID-19 era, several probiotic strains were found to be clinically effective in addressing gastrointestinal infectious diseases, the common cold and flu. However, the mechanism by which probiotics exerted their antiviral effects remained relatively unclear during that period. Nevertheless, probiotics, Lactococcus lactis strain Plasma (LC-Plasma), and others have gained attention for their unique ability to modulate the immune system and demonstrate antiviral properties. While some probiotics have shown promise in alleviating gastrointestinal symptoms linked to COVID-19, their direct effectiveness in treating or preventing COVID-19 progression has not yet been conclusively established. As we transition into the post-COVID-19 era, the relationship between COVID-19 and plasmacytoid dendritic cells (pDCs), a vital component of the innate immune system, has been gradually elucidated. These findings are now being applied in developing novel vaccines and treatments involving interferons and in immune activation research using probiotics as adjuvants, comparable to CpG-DNA through TLR9. The role of the local innate immune system, including pDCs, as the first line of defense against viral infections has gained increasing interest. Moving forward, insight of the immune system and the crosstalk between probiotics and the innate immune system is expected to highlight the role of probiotics in adjunctive immunoregulatory therapy. In combination with drug treatments, probiotics may play a more substantial role in enhancing immune responses. The immunoregulatory approach using probiotics such as LC-Plasma, which can induce anti-infectious factors such as interferons, holds promise as a viable therapeutic and prophylactic option against viral infectious diseases due to their good safety profile and protective efficacy.

Joint evaluation of placebo and treatment effects in cluster randomized trials by causal inference models

The term placebo effect refers to the psychobiological effect of a patient's knowledge or belief of being treated. A placebo effect is patient-driven, which makes it fundamentally different from the usual treatment effect resulting from external actions. In modern clinical research, the presence of a placebo effect is often treated as a nuisance issue, something to be "adjusted away" in estimating a treatment effect of primary interest. However, from a patient-centered perspective, we believe that a possible placebo produces substantial improvements in patient-centered outcomes. Understanding placebo effects is therefore an important part of patient-centered outcomes research. The available methods for estimating placebo effects are designed for individually randomized trials and are not directly applicable to cluster randomized trials (CRTs). There are several challenges in estimating placebo effects in CRTs. A major challenge is the possible presence of interference within clusters, in the sense that a subject's outcome may depend on the beliefs subjects in the same cluster about treatment assignment (mentality) and therefore possible correlation in outcome and mentality among subjects exists in the same cluster. In this article, we extend the previously developed causal inference framework to also encompass CRTs, using the G-Computation and inverse probability weighting (IPW) approaches. We also develop methodologies and further extend the G-Computation and IPW approaches to handle missingness for jointly evaluating placebo effect and treatment-specific effect, specifically in the context of CRTs. The proposed methods are demonstrated in simulation studies and a cluster randomized trial on effect of fermented dairy drink.

Associations of dietary patterns with common infections and antibiotic use among Finnish preschoolers

Background

Preschoolers suffer frequently from infections. Although nutrition plays a key role in immune function, very little is known about the impact of overall diet on preschoolers' infections.

Objective

To assess the associations between dietary patterns, common infections and antibiotic use among Finnish preschoolers.

Design

The study included 721 3-6-year-old preschoolers participating in the cross-sectional DAGIS survey. Parents retrospectively reported the number of common colds, gastroenteritis episodes and antibiotic courses their children had acquired during the past year. Food consumption outside preschool hours was recorded using a food frequency questionnaire. Dietary patterns were derived from the consumption frequencies using principal component analysis. Associations between the thirds of the dietary pattern scores and the outcomes were analysed using logistic and negative binomial regression models.

Results

Prevalence of common colds was lower in moderate and high adherence to the sweets-and-treats pattern than in low adherence (prevalence ratio [PR]: 0.89, 95% confidence interval [CI]: 0.80-1.00, and PR: 0.88, 95% CI: 0.79-0.99, respectively) and higher in high adherence to the health-conscious pattern than in low adherence (PR: 1.13, 95% CI: 1.01-1.27) after adjusting for age, sex, number of children living in the same household, frequency of preschool attendance, family's highest education and probiotic use. The risk of ≥1 gastroenteritis episode and the prevalence of antibiotic courses were lower in moderate adherence to the sweets-and-treats pattern than in low adherence (odds ratio [OR]: 0.63, 95% CI: 0.44-0.92 and PR: 0.77, 95% CI: 0.59-1.00, respectively).

Conclusions

The results were unexpected. Parents who were most health-conscious of their children's diet might also have been more aware of their children's illness.

Intermodulation of gut-lung axis microbiome and the implications of biotics to combat COVID-19

The novel coronavirus disease pandemic caused by the COVID-19 virus has infected millions of people around the world with a surge in transmission and mortality rates. Although it is a respiratory viral infection that affects airway epithelial cells, a diverse set of complications, including cytokine storm, gastrointestinal disorders, neurological distress, and hyperactive immune responses have been reported. However, growing evidence indicates that the bidirectional crosstalk of the gut-lung axis can decipher the complexity of the disease. Though not much research has been focused on the gut-lung axis microbiome, there is a translocation of COVID-19 infection from the lung to the gut through the lymphatic system resulting in disruption of gut permeability and its integrity. It is believed that detailed elucidation of the gut-lung axis crosstalk and the role of microbiota can unravel the most significant insights on the discovery of diagnosis using microbiome-based-therapeutics for COVID-19. This review calls attention to relate the influence of dysbiosis caused by COVID-19 and the involvement of the gut-lung axis. It presents first of its kind details that concentrate on the momentousness of biotics in disease progression and restoration. Communicated by Ramaswamy H. Sarma.

Development of a live biotherapeutic throat spray with lactobacilli targeting respiratory viral infections

Respiratory viruses such as influenza viruses, respiratory syncytial virus (RSV), and coronaviruses initiate infection at the mucosal surfaces of the upper respiratory tract (URT), where the resident respiratory microbiome has an important gatekeeper function. In contrast to gut-targeting administration of beneficial bacteria against respiratory viral disease, topical URT administration of probiotics is currently underexplored, especially for the prevention and/or treatment of viral infections. Here, we report the formulation of a throat spray with live lactobacilli exhibiting several in vitro mechanisms of action against respiratory viral infections, including induction of interferon regulatory pathways and direct inhibition of respiratory viruses. Rational selection of Lactobacillaceae strains was based on previously documented beneficial properties, up-scaling and industrial production characteristics, clinical safety parameters, and potential antiviral and immunostimulatory efficacy in the URT demonstrated in this study. Using a three-step selection strategy, three strains were selected and further tested in vitro antiviral assays and in formulations: Lacticaseibacillus casei AMBR2 as a promising endogenous candidate URT probiotic with previously reported barrier-enhancing and anti-pathogenic properties and the two well-studied model strains Lacticaseibacillus rhamnosus GG and Lactiplantibacillus plantarum WCFS1 that display immunomodulatory capacities. The three strains and their combination significantly reduced the cytopathogenic effects of RSV, influenza A/H1N1 and B viruses, and HCoV-229E coronavirus in co-culture models with bacteria, virus, and host cells. Subsequently, these strains were formulated in a throat spray and human monocytes were employed to confirm the formulation process did not reduce the interferon regulatory pathway-inducing capacity. Administration of the throat spray in healthy volunteers revealed that the lactobacilli were capable of temporary colonization of the throat in a metabolically active form. Thus, the developed spray with live lactobacilli will be further explored in the clinic as a potential broad-acting live biotherapeutic strategy against respiratory viral diseases.

Auxotrophic Lactobacillus Expressing Porcine Rotavirus VP4 Constructed Using CRISPR-Cas9D10A System Induces Effective Immunity in Mice

Porcine rotavirus (PoRV) mainly causes acute diarrhea in piglets under eight weeks of age and has potentially high morbidity and mortality rates. As vaccine carriers for oral immunization, lactic acid bacteria (LAB) are an ideal strategy for blocking PoRV infections. However, the difficulty in knocking out specific genes, inserting foreign genes, and the residues of antibiotic selection markers are major challenges for the oral vaccination of LAB. In this study, the target gene, alanine racemase (alr), in the genome of Lactobacillus casei strain W56 (L. casei W56) was knocked out to construct an auxotrophic L. casei strain (L. casei Δalr W56) using the CRISPR-Cas9D10A gene editing system. A recombinant strain (pPG-alr-VP4/Δalr W56) was constructed using an electrotransformed complementary plasmid. Expression of the alr-VP4 fusion protein from pPG-alr-VP4/Δalr W56 was detected using Western blotting. Mice orally immunized with pPG-alr-VP4/Δalr W56 exhibited high levels of serum IgG and mucosal secretory immunoglobulin A (SIgA), which exhibited neutralizing effects against PoRV. Cytokines levels in serum detected using ELISA, indicated that the recombinant strain induced an immune response dominated by Th2 cells. Our data suggest that pPG-alr-VP4/Δalr W56, an antibiotic-resistance-free LAB, provides a safer vaccine strategy against PoRV infection.

Dairy-Based Probiotic-Fermented Functional Foods: An Update on Their Health-Promoting Properties

Numerous studies have shown a link between the consumption of fermented dairy foods and improved health outcomes. Since the early 2000s, especially probiotic-based fermented functional foods, have had a revival in popularity, mostly as a consequence of claims made about their health benefits. Among them, fermented dairy foods have been associated with obesity prevention and in other conditions such as chronic diarrhea, hypersensitivity, irritable bowel syndrome, Helicobacter pylori infection, lactose intolerance, and gastroenteritis which all are intimately linked with an unhealthy way of life. A malfunctioning inflammatory response may affect the intestinal epithelial barrier’s ability to function by interfering with the normal metabolic processes. In this regard, several studies have shown that fermented dairy probiotics products improve human health by stimulating the growth of good bacteria in the gut at the same time increasing the production of metabolic byproducts. The fermented functional food matrix around probiotic bacteria plays an important role in the survival of these strains by buffering and protecting them from intestinal conditions such as low pH, bile acids, and other harsh conditions. On average, cultured dairy products included higher concentrations of lactic acid bacteria, with some products having as much as 109/mL or g. The focus of this review is on fermented dairy foods and associated probiotic products and their mechanisms of action, including their impact on microbiota and regulation of the immune system. First, we discussed whey and whey-based fermented products, as well as the organisms associated with them. Followed by the role of probiotics, fermented-product-mediated modulation of dendritic cells, natural killer cells, neutrophils, cytokines, immunoglobulins, and reinforcement of gut barrier functions through tight junction. In turn, providing the ample evidence that supports their benefits for gastrointestinal health and related disorders.

Probiotics for preventing acute upper respiratory tract infections

BACKGROUND

Probiotics are live micro-organisms that may give a beneficial physiological effect when administered in adequate amounts. Some trials show that probiotic strains can prevent respiratory infections. Even though our previously published review showed the benefits of probiotics for acute upper respiratory tract infections (URTIs), several new studies have been published. This is an update of a review first published in 2011 and updated in 2015.

OBJECTIVES

To assess the effectiveness and safety of probiotics (any specified strain or dose), compared with placebo or no treatment, in the prevention of acute URTIs in people of all ages, at risk of acute URTIs.

SEARCH METHODS

We searched CENTRAL (2022, Issue 6), MEDLINE (1950 to May week 2, 2022), Embase (1974 to 10 May 2022), Web of Science (1900 to 10 May 2022), the Chinese Biomedical Literature Database, which includes the China Biological Medicine Database (from 1978 to 10 May 2022), the Chinese Medicine Popular Science Literature Database (from 2000 to 10 May 2022), and the Master's Degree Dissertation of Beijing Union Medical College Database (from 1981 to 10 May 2022). We searched the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov for completed and ongoing trials on 10 May 2022.

SELECTION CRITERIA

We included individual randomised controlled trials (RCTs) and cluster-RCTs comparing probiotics with placebo or no treatment to prevent acute URTIs. The participants were children, adults, or the elderly in the community, care facilities, schools, or hospitals. Our main outcomes were the number of participants diagnosed with URTIs (at least one event and at least three events), the incidence rate (number of cases/person year) of acute URTIs, and the mean duration of an episode of URTIs. Our secondary outcomes were the number of participants who were absent from childcare centre, school, or work due to acute URTIs; the number of participants who used prescribed antibiotics for acute URTIs; and the number of participants who experienced at least one adverse event from probiotics. We excluded studies if they did not specify acute respiratory infections as 'upper'; studies with more than 50% of participants vaccinated against influenza or other acute URTIs within the last 12 months; and studies with significantly different proportions of vaccinated participants between the probiotics arm and the placebo or no treatment arm.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of trials and extracted data using standard Cochrane methodological procedures. We analysed both intention-to-treat and per-protocol data and used a random-effects model. We expressed results as risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, both with 95% confidence intervals (CIs). We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 23 individual RCTs and one cluster-RCT. As one of the individual RCTs did not report outcomes in a usable way, we could only meta-analyse data from 23 trials, involving a total of 6950 participants including children (aged from one month to 11 years old), adults (mean age 37.3), and older people (mean age 84.6 years). One trial reported 22.5% flu-vaccine participants within the last 12 months, and 25.4% flu-vaccine participants during the intervention. Probiotics were more likely to be given with milk-based food in children; administered in powder form in adults; and given with milk-based food or in capsules in the elderly. Most of the studies used one or two strains (e.g. Lactobacillus plantarum HEAL9, Lactobacillus paracasei (8700:2 or N1115)) and 109 or 1011 colony-forming units (CFU)/day of probiotics for more than three months. We found that probiotics may reduce the number of participants diagnosed with URTIs (at least one event) (RR 0.76, 95% CI 0.67 to 0.87; P < 0.001; 16 studies, 4798 participants; low-certainty evidence); likely reduce the number of participants diagnosed with URTIs (at least three events) (RR 0.59, 95% CI 0.38 to 0.91; P = 0.02; 4 studies, 763 participants; moderate-certainty evidence); may reduce the incidence rate (number of cases/person year) of URTIs (rate ratio 0.82, 95% CI 0.73 to 0.92, P = 0.001; 12 studies, 4364 participants; low-certainty evidence); may reduce the mean duration of an episode of acute URTIs (MD -1.22 days, 95% CI -2.12 to -0.33; P = 0.007; 6 studies, 2406 participants; low-certainty evidence); likely reduce the number of participants who used prescribed antibiotics for acute URTIs (RR 0.58, 95% CI 0.42 to 0.81; P = 0.001; 6 studies, 1548 participants; moderate-certainty evidence); and may not increase the number of participants who experienced at least one adverse event (RR 1.02, 95% CI 0.90 to 1.15; P = 0.79; 8 studies, 2456 participants; low-certainty evidence). Evidence showing a decrease in the number of people absent from childcare centre, school, or work due to acute URTIs with probiotics is very uncertain (RR 0.14, 95% CI 0.03 to 0.59; 1 study, 80 participants; very low-certainty evidence). Adverse events from probiotics were minor, and most commonly gastrointestinal symptoms, such as vomiting, flatulence, diarrhoea, and bowel pain.  AUTHORS' CONCLUSIONS: Overall, we found that probiotics were better than placebo or no treatment in preventing acute URTIs.

Health effects of yogurt consumption during paediatric age: a narrative review

Yogurt is a fermented milk product characterised by a peculiar nutritional composition with live and viable cultures of bacteria. Few studies have analysed the benefits of yogurt consumption on health outcomes during paediatric age. Recent epidemiological studies evaluating the nutritional impact of yogurt have demonstrated its significant contribution to nutrients intakes among children. Thus, consuming yogurt is a strategy to achieve recommended nutrient intake and healthier dietary choices, with potential impact on obesity and cardiometabolic outcome in children. Yogurt's effects on paediatric infectious diseases, gastrointestinal diseases and atopic-related disorders are ascribed to the specific probiotic strain administered. Interestingly, the benefits of yogurt consumption are most likely due to effects mediated through the gut microbiota and the enhancement of innate and adaptive immune responses. Therefore, supplementing standard yogurt cultures with probiotic strains could be useful to promote health at different paediatric ages, although more evidence is needed regarding the strain-related effects and their interplay within the paediatric immune system.

Fermented Foods and Their Role in Respiratory Health: A Mini-Review

Fermented foods (FFs) hold global attention because of their huge advantages. Their health benefits, palatability, preserved, tasteful, and aromatic properties impart potential importance in the comprehensive evaluation of FFs. The bioactive components, such as minerals, vitamins, fatty acids, amino acids, and other phytochemicals synthesized during fermentation, provide consumers with several health benefits. Fermentation of food is an ancient process that has met with many remarkable changes owing to the development of scientific technologies over the years. Initially, fermentation relied on back-slapping. Nowadays, starter cultures strains are specifically chosen for the type of fermentation process. Modern biotechnological methods are being implemented in the fermentation process to achieve the desired product in high quality. Respiratory and gastrointestinal tract infections are the most severe health issues affecting human beings of all age groups, especially children and older adults, during this COVID-19 pandemic period. Studies suggest that the consumption of probiotic Lactobacillus strains containing fermented foods protects the subjects from common infectious diseases (CIDs, which is classified as upper respiratory tract infections, lower respiratory tract infections and gastrointestinal infections) by improving the host’s immune system. Further studies are obligatory to develop probiotic-based functional FFs that are effective against CIDs. Presently, we are urged to find alternative, safe, and cost-effective prevention measures against CIDs. The current manuscript briefs the production of FFs, functional properties of FFs, and their beneficial effects against respiratory tract infections. It summarizes the outcomes of clinical trials using human subjects on the effects of supplementation of FFs.

Functional foods as a formulation ingredients in beverages: technological advancements and constraints

As a consequence of expanded science and technical research, the market perception of consumers has shifted from standard traditional to valuable foods, which are furthermore nutritional as well as healthier in today's world. This food concept, precisely referred to as functional, focuses on including probiotics, which enhance immune system activity, cognitive response, and overall health. This review primarily focuses on functional foods as functional additives in beverages and other food items that can regulate the human immune system and avert any possibility of contracting the infection. Many safety concerns must be resolved during their administration. Functional foods must have an adequate amount of specific probiotic strain(s) during their use and storage, as good viability is needed for optimum functionality of the probiotic. Thus, when developing novel functional food-based formulations, choosing a strain with strong technological properties is crucial. The present review focused on probiotics as an active ingredient in different beverage formulations and the exerting mechanism of action and fate of probiotics in the human body. Moreover, a comprehensive overview of the regulative and safety issues of probiotics-based foods and beverages formulations.

Evaluation of the Function of Probiotics, Emphasizing the Role of their Binding to the Intestinal Epithelium in the Stability and their Effects on the Immune System

Due to the importance of using cost-effective methods for therapeutic purposes, the function of probiotics as safe microorganisms and the study of their relevant functional mechanisms have recently been in the spotlight. Finding the mechanisms of attachment and stability and their beneficial effects on the immune system can be useful in identifying and increasing the therapeutic effects of probiotics. In this review, the functional mechanisms of probiotics were comprehensively investigated. Relevant articles were searched in scientific sources, documents, and databases, including PubMed, NCBI, Bactibace, OptiBac, and Bagel4. The most important functional mechanisms of probiotics and their effects on strengthening the epithelial barrier, competitive inhibition of pathogenic microorganisms, production of antimicrobials, binding and interaction with the host, and regulatory effects on the immune system were discussed.

In this regard, the attachment of probiotics to the epithelium is very important because the prerequisite for their proper functioning is to establish a proper connection to the epithelium. Therefore, more attention should be paid to the binding effect of probiotics, including sortase A, a significant factor involved in the expression of sortase-dependent proteins (SDP), on their surface as mediators of intestinal epithelial cell binding. In general, by investigating the functional mechanisms of probiotics, it was concluded that the mechanism by which probiotics regulate the immune system and adhesion capacity can directly and indirectly have preventive and therapeutic effects on a wide range of diseases. However, further study of these mechanisms requires extensive research on various aspects.

The influence of probiotics on gastrointestinal tract infections among children attending childcare: A systematic review and meta-analysis

Current literature related to the impact of probiotics on the incidence of gastrointestinal tract infections (GITIs) has shown mixed results and no systematic review available with pooled analysis exists. Thus, the aim of this systematic review was to provide contemporary evidence regarding the overall and strain-specific influence of probiotics in preventing GITIs among infants and children attending childcare centres. The review shortlisted 18 RCTs after screening through the initial search results of 779 articles. However, only 15 trials were deemed eligible, addressing at least one outcome in the pooled analysis. It is concluded that the supplementation of probiotics (overall effect) may reduce the risk of GITI episode by 26%, with Lacticaseibacillus paracasei, Limosilactobacillus reuteri and Lacticaseibacillus rhamnosus GG being specifically potent probiotic strains in reducing GITI episode, duration of infection and absence from childcare respectively. There is insufficient evidence to determine the effect of Bifidobacterium animalis subsp. lactis BB-12 based on the findings of the trials included in this review.

Theoretical benefits of yogurt-derived bioactive peptides and probiotics in COVID-19 patients - A narrative review and hypotheses

The world is currently facing a frightening coronavirus disease-2019 (COVID-19) epidemic. Severity of COVID-19 presentation is highly variable among infected individuals with increasingly recognized risk factors. Although observational studies suggested lower COVID-19 severity in populations consuming fermented foods, no controlled study investigated the role of diet. Yogurt, a fermented dairy product, exhibits interesting properties related to the presence of bioactive peptides and probiotics that may play a beneficial role in COVID-19 presentation and outcome. Peptides contained in yogurt are responsible for angiotensin-converting enzyme-inhibitory, bradykinin potentiating, antiviral, anti-inflammatory, antithrombotic, and antioxidant effects. The types and activity of these peptides vary widely depending on their amino acid sequence, on the probiotics used in yogurt production and on intestinal digestion. Additionally, probiotics used in yogurt exhibit direct angiotensin-converting enzyme-inhibitory, antiviral and immune boosting activities. Since COVID-19 pathogenesis involves angiotensin II accumulation and bradykinin deficiency, yogurt bioactive peptides appear as potentially beneficial. Therefore, epidemiological investigations and randomized controlled clinical trials to evaluate the exact role of yogurt consumption on COVID-19 manifestations and outcome should be encouraged.

Effect of probiotic fermented dairy products on incidence of respiratory tract infections: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Previous studies have suggested that the consumption of probiotic fermented dairy products (PFDP) may have a protective effect on respiratory tract infections (RTIs). However, the results of studies are inconclusive. We aimed to systematically investigate the effect of PFDP on RTIs by performing a meta-analysis of randomized controlled trials (RCTs).

METHODS

PubMed and Scopus databases were systematically searched up to October 2020 to identify eligible RCTs. Meta-analysis outcomes were risk of incidence of upper (URTIs ) and lower (LRTIs ) respiratory tract infections. A random-effects model was used to pool the relative risks (RR) and corresponding 95 % confidence intervals (CI) for outcomes following conception of PFDP.

RESULTS

A total of 22 RCTs, with a total sample size of 10,190 participants, were included in this meta-analysis. Compared with placebo, consumption of PFDP had a significant protective effect against RTIs in the overall analysis (RR = 0.81, 95 %CI: 0.74 to 0.89) and in children (RR = 0.82, 95 %CI: 0.73 to 0.93), adults (RR = 0.81, 95 %CI: 0.66 to 1.00), and elderly population (RR = 0.78, 95 %CI: 0.61 to 0.98). The significant decreased risk of RTIs was also observed for URTIs (RR = 0.83, 95 %CI: 0.73 to 0.93), while, this effect was marginal for LRTIs (RR = 0.78, 95 %CI: 0.60 to 1.01, P = 0.06). The disease-specific analysis showed that PFDP have a protective effect on pneumonia (RR = 0.76, 95 %CI: 0.61 to 0.95) and common cold (RR = 0.68, 95 %CI: 0.49 to 0.96).

CONCLUSIONS

Consumption of PFDP is a potential dietary approach for the prevention of RTIs.

Probiotics for the Prevention of Acute Respiratory-Tract Infections in Older People: Systematic Review

The aim of this systematic review was to present the indirect influence of probiotics on the incidence and duration of acute upper respiratory-tract infections in older people, by regulating the immune system. Eight randomized, placebo-controlled clinical trials met the inclusion criteria, considering the threshold of older people being 60 years and over. Single strain probiotics were used in all studies, including three probiotic strains used in fermented foods: Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1, Lacticaseibacillus paracasei subsp. paracasei CNCM I-1518 and Lacticaseibacillusparacasei Shirota, and three probiotic strains used as food supplements: Loigolactobacillus coryniformis K8 CECT5711, Bacillus subtilis CU1 and Lacticaseibacillus rhamnosus GG. Current evidence showed that certain probiotic strains were better than a placebo in lowering the incidence or number of older people experiencing acute upper respiratory tract infections; however, not all probiotic strains were efficient, and not all studies reported statistically significant outcomes. More high quality large-scale properly controlled clinical studies focusing on older people are warranted.

The effect of probiotics on respiratory tract infection with special emphasis on COVID-19: Systemic review 2010-20

To evaluate the effects of probiotics on respiratory tract infection (RTI) a systematic review of randomized controlled trials (RCTs) from January 2010 to January 2020 was conducted. The PubMed, Google Scholar, Embase, Scopus, Clinicaltrials.gov, and International Clinical Trials Registry Platform databases were systematically searched for the following keywords: respiratory tract infection, probiotics, viral infection, COVID-19, and clinical trial. A total of 27 clinical trials conducted on 9433 patients with RTI plus 10 ongoing clinical studies of probiotics intervention in Coronavirus disease 2019 (COVID-19) were reviewed. The review looked at the potency of probiotics for the hindrance and/or treatment of RTI diseases, this may also apply to COVID-19. The review found that probiotics could significantly increase the plasma levels of cytokines, the effect of influenza vaccine and quality of life, as well as reducing the titer of viruses and the incidence and duration of respiratory infections. These antiviral and immune-modulating activities and their ability to stimulate interferon production recommend the use of probiotics as an adjunctive therapy to prevent COVID-19. Based on this extensive review of RCTs we suggest that probiotics are a rational complementary treatment for RTI diseases and a viable option to support faster recovery.

Ex vivo peripheral blood mononuclear cell response to R848 in children after supplementation with the probiotic Lactobacillus acidophilus NCFM/Bifidobacterium lactis Bi-07

Several studies have demonstrated a decrease in upper respiratory infection (URI) frequency and severity in subjects taking probiotic supplements. We hypothesised beneficial effects of probiotics on viral URI in children are due to modulation of inflammatory innate immune responses. We tested this hypothesis, providing children with a probiotic combination of Lactobacillus acidophilus/Bidfidobacterium animalis ssp. lactis Bi-07 (NCFM/Bi-07) and measuring levels of cytokines in response to stimulation of peripheral blood mononuclear cells (PBMCs) to toll-like receptor (TLR) 7/8 agonist resiquimod (R848). In this open label study, 21 (2 dropouts) children received probiotic containing 5×10⁹ cfu each of NCFM/(Bi-07) daily for 30 days. Whole blood was taken from each subject at study entry and 30 days for culture of PBMCs. PBMCs stimulated with resiquimod (R848) or unstimulated were incubated and a panel of immune markers was measured. There was a significant decrease in the net (stimulated-null) level of myeloid progenitor inhibitory factor 1 (MPIF-1) (mean decrease 0.1 ng/ml, 95% confidence interval 0.01-0.24, P=0.032) following probiotic supplementation. The change in immune marker levels after supplementation, when analysed together with respect to expected inflammatory/anti-inflammatory effects, was increased for interleukin (IL)-10 and decreased for MPIF-1, IL-8, interferon gamma induced protein 10, macrophage inflammatory protein 3 alpha (MIP-3α) and E-selectin (P=0.01). Adverse events were mild. In conclusion, supplementation with this probiotic combination was safe and resulted in significant modulation of PBMC limited immune response to TLR7/8 agonist R848 and in levels of MPIF-1 and MIP-3α. The anti-inflammatory effect may be one mechanism by which probiotics modulate the immune system however further study is needed.

Effects of a Fermented Dairy Drink Containing Lacticaseibacillus paracasei subsp. paracasei CNCM I-1518 (Lactobacillus casei CNCM I-1518) and the Standard Yogurt Cultures on the Incidence, Duration, and Severity of Common Infectious Diseases: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

There is considerable interest in the role of probiotics in immune function. The objective of this systematic review and meta-analysis was to assess the effects of the consumption of a fermented dairy drink containing Lacticaseibacillus paracasei subsp. paracasei CNCM I-1518 (the previous taxonomic nomenclature was Lactobacillus casei CNCM I-1518, prior to the nomenclature change in April 2020) and the standard yogurt cultures (hereinafter referred to collectively as “FDD”) on common infectious diseases (CIDs) in generally healthy children and adults. Nine literature databases were searched, and nine randomized controlled trials from eight publications were eligible for inclusion. Combined effect sizes were determined for three metrics of CID incidence, two metrics of CID duration, and one metric of CID severity. Compared to the control, the consumption of the FDD resulted in (1) a significant reduction in the odds of experiencing ≥1 CID (odds ratio (OR) (with a 95% confidence interval (CI)): 0.81 (0.66, 0.98); p = 0.029); (2) a significant reduction in mean CIDs per subject (−0.09 (−0.15, −0.04); p = 0.001); and (3) a trend towards reduced risk in cumulative CIDs (relative risk (RR): 0.91 (0.82, 1.01); p = 0.082). The consumption of the FDD had no significant effect on CID duration or severity. Based on the studies conducted thus far, these results suggest that the FDD may reduce CID incidence in the general population.

Does probiotic consumption reduce antibiotic utilization for common acute infections? A systematic review and meta-analysis

BACKGROUND

Overall reduction of antibiotic use is a widely adopted public health goal. Given evidence that consuming probiotics reduce the incidence, duration and/or severity of certain types of common acute infections, we hypothesized that probiotics are associated with reduced antibiotic use. This systematic review of randomized controlled trials (RCTs) assessed the impact of probiotic supplementation (any strain, dose or duration), compared to placebo, on antibiotic utilization for common, acute infections in otherwise healthy people of all ages.

METHODS

We searched 13 electronic databases including MEDLINE, Embase and CENTRAL from inception to 17th January 2017. Backward and forward citation searches were also conducted. Two reviewers independently selected studies for inclusion and extracted study data. We assessed risk of bias for individual studies using criteria adapted from the Centre for Reviews and Dissemination, and the quality of evidence for each outcome was assessed using the GRADE system. Studies that evaluated similar outcomes were pooled statistically in meta-analyses using a random-effects model.

RESULTS

We screened 1533 citations, and of these, 17 RCTs met our predefined inclusion criteria. All 17 were conducted in infants and/or children with a primary aim of preventing acute respiratory tract infections, acute lower digestive tract infections or acute otitis media. Included studies used 13 probiotic formulations, all comprising single or combination Lactobacillus and Bifidobacterium delivered in a range of food or supplement products. Mean duration of probiotic supplementation ranged from 4 days to 9 months. Trial quality was variable. Meta-analysis demonstrated that infants and children who received probiotics to prevent acute illnesses had a lower risk of being prescribed antibiotics, relative to those who received placebo (Pooled Relative Risk = 0.71, 95% CI: 0.54-0.94). When restricted to five studies with a low risk of bias, the pooled relative risk was 0.46 (95% CI: 0.23-0.97). Significant statistical heterogeneity was present in effect size estimates, which appeared to be due to one trial which could partly be considered as an outlier.

CONCLUSIONS

Probiotics, provided to reduce the risk for common acute infections, may be associated with reduced antibiotic use in infants and children. Additional well-designed studies are needed to substantiate these findings in children and explore similar findings in other population groups.

The potential application of probiotics and prebiotics for the prevention and treatment of COVID-19

COVID-19 is a pandemic disease caused by the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This new viral infection was first identified in China in December 2019, and it has subsequently spread globally. The lack of a vaccine or curative treatment for COVID-19 necessitates a focus on other strategies to prevent and treat the infection. Probiotics consist of single or mixed cultures of live microorganisms that can beneficially affect the host by maintaining the intestinal or lung microbiota that play a major role in human health. At present, good scientific evidence exists to support the ability of probiotics to boost human immunity, thereby preventing colonization by pathogens and reducing the incidence and severity of infections. Herein, we present clinical studies of the use of probiotic supplementation to prevent or treat respiratory tract infections. These data lead to promising benefits of probiotics in reducing the risk of COVID-19. Further studies should be conducted to assess the ability of probiotics to combat COVID-19.

Safety and functional enrichment of gut microbiome in healthy subjects consuming a multi-strain fermented milk product: a randomised controlled trial

Many clinical studies have evaluated the effect of probiotics, but only a few have assessed their dose effects on gut microbiota and host. We conducted a randomized, double-blind, controlled intervention clinical trial to assess the safety (primary endpoint) of and gut microbiota response (secondary endpoint) to the daily ingestion for 4 weeks of two doses (1 or 3 bottles/day) of a fermented milk product (Test) in 96 healthy adults. The Test product is a multi-strain fermented milk product, combining yogurt strains and probiotic candidate strains Lactobacillus paracasei subsp. paracasei CNCM I-1518 and CNCM I-3689 and Lactobacillus rhamnosus CNCM I-3690. We assessed the safety of the Test product on the following parameters: adverse events, vital signs, hematological and metabolic profile, hepatic, kidney or thyroid function, inflammatory markers, bowel habits and digestive symptoms. We explored the longitudinal gut microbiota response to product consumption and dose, by 16S rRNA gene sequencing and functional contribution by shotgun metagenomics. Safety results did not show any significant difference between the Test and Control products whatever the parameters assessed, at the two doses ingested daily over a 4-week-period. Probiotic candidate strains were detected only during consumption period, and at a significantly higher level for the three strains in subjects who consumed 3 products bottles/day. The global structure of the gut microbiota as assessed by alpha and beta-diversity, was not altered by consumption of the product for four weeks. A zero-inflated beta regression model with random effects (ZIBR) identified a few bacterial genera with differential responses to test product consumption dose compared to control. Shotgun metagenomics analysis revealed a functional contribution to the gut microbiome of probiotic candidates.

Probiotics: A Dietary Factor to Modulate the Gut Microbiome, Host Immune System, and Gut-Brain Interaction

Various benefits of probiotics to the host have been shown in numerous human clinical trials. These organisms have been proposed to act by improving the balance of the gut microbiota and enhancing the production of short-chain fatty acids, as well as by interacting with host cells in the gastrointestinal tract, including immune cells, nerve cells, and endocrine cells. Although the stimulation of host cells by probiotics and subsequent signaling have been explained by in vitro experiments and animal studies, there has been some skepticism as to whether probiotics can actually interact with host cells in the human gastrointestinal tract, where miscellaneous indigenous bacteria coexist. Most recently, it has been shown that the ileal microbiota in humans after consumption of a fermented milk is occupied by probiotics for several hours, indicating that there is adequate opportunity for the ingested strain to stimulate the host cells continuously over a period of time. As the dynamics of ingested probiotics in the human gastrointestinal tract become clearer, further progress in this research area is expected to elucidate their behavior within the tract, as well as the mechanism of their physiological effects on the host.

Postbiotics for Preventing and Treating Common Infectious Diseases in Children: A Systematic Review

Postbiotics have recently been tentatively defined as bioactive compounds produced during a fermentation process (including microbial cells, cell constituents and metabolites) that supports health and/or wellbeing. Postbiotics are currently available in some infant formulas and fermented foods. We systematically reviewed evidence on postbiotics for preventing and treating common infectious diseases among children younger than 5 years. The PubMed, Embase, SpringerLink, and ScienceDirect databases were searched up to March 2019 for randomized controlled trials (RCTs) comparing postbiotics with placebo or no intervention. Seven RCTs involving 1740 children met the inclusion criteria. For therapeutic trials, supplementation with heat-killed Lactobacillus acidophilus LB reduced the duration of diarrhea (4 RCTs, n = 224, mean difference, MD, -20.31 h, 95% CI -27.06 to -13.57). For preventive trials, the pooled results from two RCTs (n = 537) showed that heat-inactivated L. paracasei CBA L74 versus placebo reduced the risk of diarrhea (relative risk, RR, 0.51, 95% CI 0.37-0.71), pharyngitis (RR 0.31, 95% CI 0.12-0.83) and laryngitis (RR 0.44, 95% CI 0.29-0.67). There is limited evidence to recommend the use of specific postbiotics for treating pediatric diarrhea and preventing common infectious diseases among children. Further studies are necessary to determine the effects of different postbiotics.

Intestinal Microbiota-Associated Metabolites: Crucial Factors in the Effectiveness of Herbal Medicines and Diet Therapies

Although the efficacy of herbal medicines (HMs) and traditional Chinese medicines (TCMs) in human diseases has long been recognized, their development has been hindered in part by a lack of a comprehensive understanding of their mechanisms of action. Indeed, most of the compounds extracted from HMs can be metabolized into specific molecules by host microbiota and affect pharmacokinetics and toxicity. Moreover, HMs modulate the constitution of host intestinal microbiota to maintain a healthy gut ecology. Dietary interventions also show great efficacy in treating some refractory diseases, and the commensal microbiota potentially has significant implications for the high inter-individual differences observed in such responses. Herein, we mainly discuss the contribution of the intestinal microbiota to high inter-individual differences in response to HMs and TCMs, and especially the already known metabolites of the HMs produced by the intestinal microbiota. The contribution of commensal microbiota to the inter-individual differences in response to dietary therapy is also briefly discussed. This review highlights the significance of intestinal microbiota-associated metabolites to the efficiency of HMs and dietary interventions. Our review may help further identify the mechanisms leading to the inter-individual differences in the effectiveness of HM and dietary intervention from the perspective of their interactions with the intestinal microbiota.

The role of yogurt in food-based dietary guidelines

In the modern food technology era, one of the aims of food safety and quality is to eliminate or reduce the number of microorganisms in food. This may now be changing. In particular, the importance of live microorganisms as beneficial food constituents is now being recognized. Microorganisms present in food that contribute to the human diet include not only viable bacteria but also metabolites and bioactive components. Yogurt is one of the most biologically active foods consumed by humans. It is an excellent source of proteins, vitamins, and minerals. Additionally, the nutritional value is especially high relative to cost. Potential nutritional benefits are also associated with the ingestion of the bacteria that are ordinarily present at the time of consumption. Thus, yogurt serves as a major source of live bacteria in the human diet, as well as a delivery vehicle for added probiotic bacteria. Yogurt may provide a simple and affordable solution for enhancing the nutritional value of the diet, including the intake of live bacteria and their metabolites. A further benefit may be obtained when yogurt is used as a carrier for specific probiotic bacteria and/or prebiotic compounds. These factors suggest that yogurt could have a more visible role in food-based dietary guidelines.

Probiotics and Paraprobiotics in Viral Infection: Clinical Application and Effects on the Innate and Acquired Immune Systems

Recently, the risk of viral infection has dramatically increased owing to changes in human ecology such as global warming and an increased geographical movement of people and goods. However, the efficacy of vaccines and remedies for infectious diseases is limited by the high mutation rates of viruses, especially, RNA viruses. Here, we comprehensively review the effectiveness of several probiotics and paraprobiotics (sterilized probiotics) for the prevention or treatment of virally-induced infectious diseases. We discuss the unique roles of these agents in modulating the cross-talk between commensal bacteria and the mucosal immune system. In addition, we provide an overview of the unique mechanism by which viruses are eliminated through the stimulation of type 1 interferon production by probiotics and paraprobiotics via the activation of dendritic cells. Although further detailed research is necessary in the future, probiotics and/or paraprobiotics are expected to be among the rational adjunctive options for the treatment of various viral diseases.

Anti-inflammatory activities of Maillard reaction products from whey protein isolate fermented by Lactobacillus gasseri 4M13 in lipopolysaccharide-stimulated RAW264.7 cells

Maillard reaction products formed from whey protein isolate (WPI) and sugar have been shown to have an anti-inflammatory effect in vitro. Here, we incubated WPI and galactose (GWA) in an aqueous solution at 65°C for 24 h to produce a glycated conjugate, which was then fermented using Lactobacillus gasseri 4M13 to obtain the fermented product (F-GWA). We demonstrated that F-GWA had an anti-inflammatory effect on lipopolysaccharide (LPS)-stimulated RAW264.7 cells. It reduced both LPS-stimulated nitric oxide production and LPS-stimulated increases in the gene expression levels of tumor necrosis factor-α and cyclooxygenase-2 in a dose-dependent manner. Furthermore, F-GWA inhibited the LPS-induced phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase, members of the mitogen-activated protein kinase family. The glycation process was evaluated by measuring fluorescence intensity and the furosine concentration during the Maillard reaction to form GWA. The protein modifications of WPI were analyzed using MALDI-TOF tandem mass spectrometry. We found that the combination of the Maillard reaction and L. gasseri 4M13 fermentation increased the prebiotic properties of GWA as well as organic acid production, compared with the nonreacted WPI and galactose.

Probiotics for preventing acute otitis media in children

BACKGROUND

Acute otitis media (AOM), or acute middle ear infection, is one of the most frequently occurring childhood diseases, and the most common reason given for prescribing antibiotics in this age group. Guidelines often recommend antibiotics as first-line treatment for severe AOM. However, antibiotics also lead to antibiotic resistance, so preventing episodes of AOM is an urgent priority.

OBJECTIVES

To assess the effects of probiotics to prevent the occurrence and reduce the severity of acute otitis media in children.

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, and three other databases (October 2018), two trial registers (October 2018), and conducted a backwards and forwards citation analysis (August 2018). We did not apply any language, publication date, or publication status restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of children (aged up to 18 years), comparing probiotics with placebo, usual care, or no probiotic.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility of trials for inclusion and risk of bias of the included trials, and extracted data using pre-piloted data extraction forms. We analysed dichotomous data as either risk ratio (RR) or odds ratios (OR) and continuous data as mean differences (MD).

MAIN RESULTS

We included 17 RCTs involving 3488 children, of which 16 RCTs were included in the meta-analyses. Of the 16 RCTs that reported the mean age of children, mean age overall was 2.4 years; in 4 RCTs the mean age of children participating in the trial was less than 1 year old; in 2 RCTs the mean age was between 1 and 2 years old; and in 10 RCTs the mean age was older than 2 years. Probiotic strains evaluated by the trials varied, with 11 of the included RCTs evaluating Lactobacillus-containing probiotics, and six RCTs evaluating Streptococcus-containing probiotics.The proportion of children (i.e. the number of children in each group) experiencing one or more episodes of AOM during the treatment was lower for those taking probiotics (RR 0.77, 95% confidence interval (CI) 0.63 to 0.93; 16 trials; 2961 participants; number needed to treat for an additional beneficial outcome (NNTB) = 10; moderate-certainty evidence).Post hoc subgroup analysis found that among children not prone to otitis media, a lower proportion of children receiving probiotics experienced AOM (RR 0.64, 95% CI 0.49 to 0.84; 11 trials; 2227 participants; NNTB = 9; moderate-certainty evidence). However, among children who were otitis prone, there was no difference between probiotic and comparator groups (RR 0.97, 95% CI 0.85 to 1.11; 5 trials; 734 participants; high-certainty evidence). The test for subgroup differences was significant (P = 0.007).None of the included trials reported on the severity of AOM.The proportion of children experiencing adverse events did not differ between the probiotic and comparator groups (OR 1.54, 95% CI 0.60 to 3.94; 4 trials; 395 participants; low-certainty evidence).Probiotics decreased the proportion of children taking antibiotics for any infection (RR 0.66, 95% CI 0.51 to 0.86; 8 trials; 1768 participants; NNTB = 8; moderate-certainty evidence). Test for subgroup differences (use of antibiotic specifically for AOM, use of antibiotic for infections other than AOM) was not significant.There was no difference in the mean number of school days lost (MD -0.95, 95% CI -2.47 to 0.57; 5 trials; 1280 participants; moderate-certainty evidence). There was no difference between groups in the level of compliance in taking the intervention (RR 1.02, 95% CI 0.99 to 1.05; 5 trials; 990 participants).Probiotics decreased the proportion of children having other infections (RR 0.75, 95% CI 0.65 to 0.87; 11 trials; 3610 participants; NNTB = 12; moderate-certainty evidence). Test for subgroup differences (acute respiratory infections, gastrointestinal infections) was not significant.Probiotic strains trialled and their dose, frequency, and duration of administration varied considerably across studies, which likely contributed to the substantial levels of heterogeneity. Sensitivity testing of funnel plots did not reveal publication bias.

AUTHORS' CONCLUSIONS

Probiotics may prevent AOM in children not prone to AOM, but the inconsistency of the subgroup analyses suggests caution in interpreting these results. Probiotics decreased the proportion of children taking antibiotics for any infection. The proportion of children experiencing adverse events did not differ between the probiotic and comparator groups. The optimal strain, duration, frequency, and timing of probiotic administration still needs to be established.

Probiotics in the next-generation sequencing era

Technological developments, including massively parallel DNA sequencing, gnotobiotics, metabolomics, RNA sequencing and culturomics, have markedly propelled the field of microbiome research in recent years. These methodologies can be harnessed to improve our in-depth mechanistic understanding of basic concepts related to consumption of probiotics, including their rules of engagement with the indigenous microbiome and impacts on the human host. We have recently demonstrated that even during probiotic supplementation, resident gut bacteria in a subset of individuals resist the mucosal presence of probiotic strains, limiting their modulatory effect on the microbiome and on the host gut transcriptional landscape. Resistance is partly alleviated by antibiotics treatment, which enables probiotics to interact with the host at the gut mucosal interface, although rather than promoting reconstitution of the indigenous microbiome and of the host transcriptional profile, they inhibit these components from returning to their naïve pre-antibiotic configurations. In this commentary, we discuss our findings in the context of previous and recent works, and suggest that incorporating the state-of-the-art methods currently utilized in microbiome research into the field of probiotics may lead to improved understanding of their mechanisms of activity, as well as their efficacy and long-term safety.

Probiotics for respiratory tract infections in children attending day care centers-a systematic review

Probiotics have been suggested to have a preventive effect on respiratory tract infections (RTIs), but limited evidence exist on strain-specific effects. The main aim of this systematic review and meta-analysis was to evaluate strain-specific probiotic effects on RTIs in children attending day care. We included 15 RCTs with 5121 children in day care settings (aged 3 months to 7 years), but due to high diversity in reported outcomes, different number of RCTs were available for evaluated outcomes. Twelve RCTs (n = 4527) reported results which could be compared in at least one outcome of the meta-analysis. Compared to placebo, Lactobacillus rhamnosus GG (LGG) significantly reduced duration of RTIs (three RCTs, n = 1295, mean difference - 0.78 days, 95% confidence interval (CI) - 1.46; - 0.09), whereas no effect was found on other evaluated outcomes. Based on the results from two studies (n = 343), Bifidobacterium animalis subsp. lactis BB-12 showed no effect on duration of RTIs or on absence from day care. Meta-analyses on other strains or their combination were not possible due to limited data and different outcome measures.Conclusion: LGG is modestly effective in decreasing the duration of RTIs. More RCTs investigating specific probiotic strains or their combinations in prevention of RTIs are needed. What is known: • Previously published systematic reviews have suggested that probiotics may have a preventive effect on respiratory infections, but limited data exist on strain specific effects. What is new: • This systematic review showed that use of Lactobacillus rhamnosus GG modestly reduces the duration of respiratory tract infections.

Guidance on the use of probiotics in clinical practice in children with selected clinical conditions and in specific vulnerable groups

AIM

The use of probiotics has been covered by many guidelines, position papers and evidence-based recommendations, but few have referred to specific patient groups or clinical indications. This review summarises recommendations and scientifically credited guidelines on the use of probiotics for children with selected clinical conditions and provides practice points.

METHODS

An expert panel was convened by the European Paediatric Association in June 2017 to define the relevant clinical questions for using probiotics in paediatric health care and review and summarise the guidelines, recommendations, position papers and high-quality evidence.

RESULTS

The panel found that specific probiotic strains were effective in preventing antibiotic-associated and nosocomial diarrhoea, treating acute gastroenteritis and treating infantile colic in breastfed infants. However, special caution is indicated for premature infants, immunocompromised and critically ill patients and those with central venous catheters, cardiac valvular disease and short-gut syndrome. This review discusses the safety of using probiotics in selected groups of paediatric patients and the quality of the available products providing practice points based on proved findings.

CONCLUSION

Efficacy of probiotics is strain specific. Their benefits are currently scientifically proven for their use in selected clinical conditions in children and not recommended for certain patient groups.

Critical appraisal of RCTs by 3rd year undergraduates after short courses in EBM compared to expert appraisal

Introduction: An essential aim of courses in evidence-based medicine (EBM) is to improve the skills for reading and interpreting medical literature adequately. Regarding the conceptual framework, it is important to consider different educational levels. Aim: Our primary aim was to investigate the applicability of different instruments for the assessment of methodological study quality by 3rd grade students after short courses in EBM. Our secondary outcomes were agreement with expert assessments and student's knowledge and competences. Methods: We conducted four short courses in EBM of 90 minutes each for health care management and medical students focused on critical appraisal of the literature. At the end, the students assessed five publications about randomized controlled trials (RCTs) using five different instruments; the results were compared to expert assessments. Results: In total, 167 students participated in our EBM courses. Students' assessments showed a non-systematic over- and underestimation of risk of bias compared to expert assessments with no clear direction. Agreement with expert assessments ranged between 66% to over 80%. Across RCTs, evidence was found that the choice of instrument had an impact on agreement rates between expert and student assessments (p=0.0158). Three RCTs showed an influence of the instrument on the agreement rate (p<0.05 each). Discussion: Our results contrast sharply with those of many other comparable evaluations. Reasons may be a lack of students' motivation due to the compulsory courses, and the comparison to a reference standard in addition to self-ratings causing objectivity. Conclusion: Undergraduates should become familiar with the principles of EBM, including research methods, and the reading of scientific papers as soon as possible. For a deeper understanding, clinical experience seems to be an indispensable precondition. Based on our results, we would recommend an integration of lectures about EBM and critical appraisal at least twice during studies and with greater intensity shortly before graduation.

Immune-Mediated Mechanisms of Action of Probiotics and Synbiotics in Treating Pediatric Intestinal Diseases

The pediatric population is continually at risk of developing infectious and inflammatory diseases. The treatment for infections, particularly gastrointestinal conditions, focuses on oral or intravenous rehydration, nutritional support and, in certain case, antibiotics. Over the past decade, the probiotics and synbiotics administration for the prevention and treatment of different acute and chronic infectious diseases has dramatically increased. Probiotic microorganisms are primarily used as treatments because they can stimulate changes in the intestinal microbial ecosystem and improve the immunological status of the host. The beneficial impact of probiotics is mediated by different mechanisms. These mechanisms include the probiotics' capacity to increase the intestinal barrier function, to prevent bacterial transferation and to modulate inflammation through immune receptor cascade signaling, as well as their ability to regulate the expression of selected host intestinal genes. Nevertheless, with respect to pediatric intestinal diseases, information pertaining to these key mechanisms of action is scarce, particularly for immune-mediated mechanisms of action. In the present work, we review the biochemical and molecular mechanisms of action of probiotics and synbiotics that affect the immune system.

Direct effects of fermented cow's milk product with Lactobacillus paracasei CBA L74 on human enterocytes

Cow's milk fermented with Lactobacillus paracasei CBA L74 (FM-CBAL74) exerts a preventive effect against infectious diseases in children. We evaluated if this effect is at least in part related to a direct modulation of non-immune and immune defence mechanisms in human enterocytes. Human enterocytes (Caco-2) were stimulated for 48 h with FM-CBAL74 at different concentrations. Cell growth was assessed by colorimetric assay; cell differentiation (assessed by lactase expression), tight junction proteins (zonula occludens1 and occludin), mucin 2, and toll-like receptor (TRL) pathways were analysed by real-time PCR; innate immunity peptide synthesis, beta-defensin-2 (HBD-2) and cathelicidin (LL-37) were evaluated by ELISA. Mucus layer thickness was analysed by histochemistry. FMCBA L74 stimulated cell growth and differentiation, tight junction proteins and mucin 2 expression, and mucus layer thickness in a dose-dependent fashion. A significant stimulation of HBD-2 and LL-37 synthesis, associated with a modulation of TLR pathway, was also observed. FM-CBAL74 regulates non-immune and immune defence mechanisms through a direct interaction with the enterocytes. These effects could be involved in the preventive action against infectious diseases demonstrated by this fermented product in children.

Lactobacillus paracasei feeding improves immune control of influenza infection in mice

Respiratory tract infections such as flu cause severe morbidity and mortality and are among the leading causes of death in children and adults worldwide. Commensal microbiota is critical for orchestrating tissue homeostasis and immunity in the intestine. Probiotics represent an interesting source of immune modulators and several clinical studies have addressed the potential beneficial effects of probiotics against respiratory infections. Therefore, we have investigated the mechanisms of protection conferred by L. paracasei CNCM I-1518 strain in a mouse model of influenza infection. Notably, local myeloid cells accumulation is generated in the lungs after seven days feeding with L. paracasei prior to viral infection. L. paracasei-fed mice showed reduced susceptibility to the influenza infection, associated with less accumulation of inflammatory cells in the lungs, faster viral clearance and general health improvement. Interestingly, Allobaculum was significantly increased in L. paracasei-fed mice 7 days after influenza infection, even if the gut microbiota composition was not altered overall. L. paracasei-purified peptidoglycan partially recapitulated the protective phenotype observed with the entire bacteria. Collectively, our results demonstrate that oral consumption of L. paracasei CNCM I-1518 modulates lung immunity was associated with an improved control of influenza infection. These results further extend the beneficial role for certain lactobacilli to alleviate the burden of respiratory tract infections.

Specific Signatures of the Gut Microbiota and Increased Levels of Butyrate in Children Treated with Fermented Cow's Milk Containing Heat-Killed Lactobacillus paracasei CBA L74

We recently demonstrated that cow's milk fermented with the probiotic Lactobacillus paracasei CBA L74 (FM-CBAL74) reduces the incidence of respiratory and gastrointestinal tract infections in young children attending school. This effect apparently derives from a complex regulation of non-immune and immune protective mechanisms. We investigated whether FM-CBAL74 could regulate gut microbiota composition and butyrate production. We randomly selected 20 healthy children (12 to 48 months) from the previous randomized controlled trial, before (t0) and after 3 months (t3) of dietary treatment with FM-CBAL74 (FM) or placebo (PL). Fecal microbiota was profiled using 16S rRNA gene amplicon sequencing, and the fecal butyrate concentration was also measured. Microbial alpha and beta diversities were not significantly different between groups prior to treatment. FM-CBAL74 but not PL treatment increased the relative abundance of Lactobacillus Individual Blautia, Roseburia, and Faecalibacterium oligotypes were associated with FM-CBAL74 treatment and demonstrated correlative associations with immune biomarkers. Accordingly, PICRUSt analysis predicted an increase in the proportion of genes involved in butyrate production pathways, consistent with an increase in fecal butyrate observed only in the FM group. Dietary supplementation with FM-CBAL74 induces specific signatures in gut microbiota composition and stimulates butyrate production. These effects are associated with changes in innate and acquired immunity.IMPORTANCE The use of a fermented milk product containing the heat-killed probiotic strain Lactobacillus paracasei CBAL74 induces changes in the gut microbiota, promoting the development of butyrate producers. These changes in the gut microbiota composition correlate with increased levels of innate and acquired immunity biomarkers.