Effects of feeding probiotics during weaning on infections and antibody responses to diphtheria, tetanus and Hib vaccines

Fish consumption benefits and PFAS risks: Epidemiology and public health recommendations

Finfish and shellfish intake (collectively referred to as fish) has been associated with health benefits, although fish often have chemical contaminants that are separately associated with health risks. The presence of chemical contaminants, however, does not inherently pose a health risk and optimizing the benefits is desirable for individual and population health. Reference doses (RfDs) and other comparison values that estimate contaminant or pollutant safety thresholds typically do not account for the benefits of the foods that carry them (e.g., fish, eggs, fruit, vegetables). Rather, these numbers are typically applied uniformly for various media such as food, soil, and water. This paper summarizes principal epidemiology studies on per- and polyfluoroalkyl substances (PFAS)-associated noncancer health indicators used by the United States Environmental Protection Agency (EPA) to develop RfDs for PFAS and compares these with the same health outcomes associated with seafood intake. Moreover, it frames these findings in relation to varying human PFAS exposures, fish intake amount, and fish type when the information is available. Further, it presents brief overviews of both general population temporal PFAS exposure trends and PFAS fish contaminant data in the United States. Finally, it discusses approaches that risk assessors and policy makers can consider in developing their fish consumption recommendations in relation to PFAS. In brief, epidemiology studies show that the benefits of fish intake generally counter the risks of PFAS exposure based on four noncancer health endpoints that EPA identified as having the greatest strength of evidence for PFAS health effects.

Nourishing the Infant Gut Microbiome to Support Immune Health: Protocol of SUN (Seeding Through Feeding) Randomized Controlled Trial

BACKGROUND

The introduction of complementary foods during the first year of life influences the diversity of the gut microbiome. How this diversity affects immune development and health is unclear.

OBJECTIVE

This study evaluates the effect of consuming kūmara or kūmara with added banana powder (resistant starch) compared to a reference control at 4 months post randomization on the prevalence of respiratory tract infections and the development of the gut microbiome.

METHODS

This study is a double-blind, randomized controlled trial of mothers and their 6-month-old infants (up to n=300) who have not yet started solids. Infants are randomized into one of 3 groups: control arm (C), standard kūmara intervention (K), and a kūmara intervention with added banana powder product (K+) to be consumed daily for 4 months until the infant is approximately 10 months old. Infants are matched for sex using stratified randomization. Data are collected at baseline (prior to commencing solid food) and at 2 and 4 months after commencing solid food (at around 8 and 10 months of age). Data and samples collected at each timepoint include weight and length, intervention adherence (months 2 and 4), illness and medication history, dietary intake (months 2 and 4), sleep (diary and actigraphy), maternal dietary intake, breast milk, feces (baseline and 4 months), and blood samples (baseline and 4 months).

RESULTS

The trial was approved by the Health and Disability Ethics Committee of the Ministry of Health, New Zealand (reference 20/NTA/9). Recruitment and data collection did not commence until January 2022 due to the COVID-19 pandemic. Data collection and analyses are expected to conclude in January 2024 and early 2025, respectively. Results are to be published in 2024 and 2025.

CONCLUSIONS

The results of this study will help us understand how the introduction of a specific prebiotic complementary food affects the microbiota and relative abundances of the microbial species, the modulation of immune development, and infant health. It will contribute to the expanding body of research that aims to deepen our understanding of the connections between nutrition, gut microbiota, and early-life postnatal health.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12620000026921; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378654.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/56772.

Dietary intervention with functional foods modulating gut microbiota for improving the efficacy of COVID-19 vaccines

Dysbiosis of the gut microbiota with aging contributes to a reduction in important cross-feeding bacterial reactions in the gut and immunosenescence, which could contribute to a decrease in vaccine efficacy. Fever, cough, and fatigue are the main signs of coronavirus disease 2019 (COVID-19); however, some patients with COVID-19 present with gastrointestinal symptoms. COVID-19 vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the best measures to reduce SARS-CoV-2 infection rates and the severity of COVID-19. The immunogenicity of COVID-19 vaccines is influenced by the composition of the gut microbiota, and the immune response to COVID-19 vaccines decreases with age. In this review, we discuss gut microbiota dysbiosis and immunosenescence in the older adults, the role of gut microbiota in improving the efficacy of COVID-19 vaccines, and dietary interventions to improve the efficacy of COVID-19 vaccines in the older adults.

Harnessing Innate Immunity to Treat Mycobacterium tuberculosis Infections: Heat-Killed Caulobacter crescentus as a Novel Biotherapeutic

Tuberculosis, caused by Mycobacterium tuberculosis (Mtb), is a serious and devastating infectious disease worldwide. Approximately a quarter of the world population harbors latent Mtb infection without pathological consequences. Exposure of immunocompetent healthy individuals with Mtb does not result in active disease in more than 90% individuals, suggesting a defining role of host immunity to prevent and/or clear early infection. However, innate immune stimulation strategies have been relatively underexplored for the treatment of tuberculosis. In this study, we used cell culture and mouse models to examine the role of a heat-killed form of a non-pathogenic microbe, Caulobacter crescentus (HKCC), in inducing innate immunity and limiting Mtb infection. We also examined the added benefits of a distinct chemo-immunotherapeutic strategy that incorporates concurrent treatments with low doses of a first-line drug isoniazid and HKCC. This therapeutic approach resulted in highly significant reductions in disseminated Mtb in the lungs, liver, and spleen of mice compared to either agent alone. Our studies demonstrate the potential of a novel innate immunotherapeutic strategy with or without antimycobacterial drugs in controlling Mtb infection in mice and open new avenues for the treatment of tuberculosis in humans.

The Gut Microbiome of Children during the COVID-19 Pandemic

The gut microbiome has been shown to play a critical role in maintaining a healthy state. Dysbiosis of the gut microbiome is involved in modulating disease severity and potentially contributes to long-term outcomes in adults with COVID-19. Due to children having a significantly lower risk of severe illness and limited sample availability, much less is known about the role of the gut microbiome in children with COVID-19. It is well recognized that the developing gut microbiome of children differs from that of adults, but it is unclear if this difference contributes to the different clinical presentations and complications. In this review, we discuss the current knowledge of the gut microbiome in children with COVID-19, with gut microbiome dysbiosis being found in pediatric COVID-19 but specific taxa change often differing from those described in adults. Additionally, we discuss possible mechanisms of how the gut microbiome may mediate the presentation and complications of COVID-19 in children and the potential role for microbial therapeutics.

The effect of probiotics on immunogenicity of spermatozoa in couples suffering from recurrent spontaneous abortion

Background

Impaired spermatozoa immunogenicity can result in pregnancy complications such as recurrent spontaneous abortion (RSA). Given that spermatozoa contact with microbiota, it is possible that inappropriate microbiota composition in the reproductive tract could result in the alteration of spermatozoa antigenicity. Probiotics, as a representative of microbiota, may therefore have a beneficial effect on this altered immunogenicity. The objective of this study was to determine the effect of probiotics on spermatozoa immunogenicity.

Methods

Twenty-five fertile couples and twenty-five RSA couples were included in this study. Spermatozoa were purified and treated with probiotics. Untreated and probiotic treated spermatozoa were evaluated for human leukocyte antigen (HLA) class I & II expression by flow cytometry. Untreated and probiotic treated spermatozoa were also cocultured with the wife’s peripheral blood mononuclear cells (PBMC) for 12 days. Then, the supernatant was assessed for IgG and APCA by enzyme-linked immunosorbent assay (ELISA) and complement-dependent cytotoxicity (CDC) assay respectively.

Results

Probiotic treatment of spermatozoa leads to an increase of HLA class I & II expression in both the fertile and RSA groups. The probiotic treatment resulted in a decrease in both IgG and APCA in the fertile group, but an increase in both IgG and APCA in the RSA group.

Conclusions

The results of this study suggest that a supplementary probiotic treatment may be useful in couples suffering from RSA with an immunologic cause, because it improves disturbed HLA expression on spermatozoa and improves disturbed APCA and IgG production in the presence of spermatozoa.

Effect of Probiotics on the Performance and Intestinal Health of Broiler Chickens Infected with Eimeria tenella

Coccidiosis is an important parasitic disease of poultry with great economic importance. Due to drug resistance issues, the study was conducted to investigate how probiotics (Lactobacillus plantarum or L. plantarum) affected oocysts per gram of feces (OPG), fecal scores, feed conversion ratio (FCR), immunomodulatory effect in terms of the cell-mediated and humoral immune response. Serum chemistry (ALT, AST, LDH, and creatinine) was measured in different treated chicken groups. mRNA expression levels of antioxidant enzymes (SOD 1 and CAT), peptide transporter 1 (PepT 1), and tight junction proteins (ZO and CLDN 1) were also examined in chicken groups infected with Eimeria tenella (E. tenella). Chickens supplemented with L. plantarum 1 × 10⁸ CFU (colony-forming unit) showed an improved cell-mediated and humoral immune response, compared with the control group (p < 0.05). Probiotics also enhanced the performance of antioxidant enzymes, PepT 1, and tight junction proteins, and improved serum chemistry (AST, ALT, and LDH), compared with control-infected, non-medicated chickens. However, no significant difference (p > 0.05) was observed in CLDN 1 expression level and creatinine in all treated chicken groups. These findings demonstrated that probiotics supplementation in the feed can protect the birds against E. tenella infection.

Metabolic Phenotype and Microbiome of Infants Fed Formula Containing Lactobacillus paracasei Strain F-19

Early childhood nutrition drives the development of the gut microbiota. In contrast to breastfeeding, feeding infant formula has been shown to impact both the gut microbiota and the serum metabolome toward a more unfavorable state. It is thought that probiotics may alter the gut microbiota and hence create a more favorable metabolic outcome. To investigate the impact of supplementation with Lactobacillus paracasei spp. paracasei strain F-19 on the intestinal microbiota and the serum metabolome, infants were fed a formula containing L. paracasei F19 (F19) and compared to a cohort of infants fed the same standard formula without the probiotic (SF) and a breast-fed reference group (BF). The microbiome, as well as serum metabolome, were compared amongst groups. Consumption of L. paracasei F19 resulted in lower community diversity of the gut microbiome relative to the SF group that made it more similar to the BF group at the end of the intervention (4 months). It also significantly increased lactobacilli and tended to increase bifidobacteria, also making it more similar to the BF group. The dominant genus in the microbiome of all infants was Bifidobacterium throughout the intervention, which was maintained at 12 months. Although the serum metabolome of the F19 group was more similar to the group receiving the SF than the BF group, increases in serum TCA cycle intermediates and decreases in several amino acids in the metabolome of the F19 group were observed, which resulted in a metabolome that trended toward the BF group. Overall, L. paracasei F19 supplementation did not override the impact of formula-feeding but did impact the microbiome and the serum metabolome in a way that may mitigate some unfavorable metabolic impacts of formula-feeding.

Probiotics as Adjuvants in Vaccine Strategy: Is There More Room for Improvement?

BACKGROUND

It has been recognized that microbiota plays a key role in shaping immune system maturation and activity. Since probiotic administration influences the microbiota composition and acts as a biological response modifier, the efficacy of an adjuvant for boosting vaccine-specific immunity is investigated.

METHODS

A review of the literature was performed, starting from the mechanisms to laboratory and clinical evidence.

RESULTS

The mechanisms, and in vitro and animal models provide biological plausibility for microbiota use. Probiotics have been investigated as adjuvants in farm conditions and as models to understand their potential in human vaccinations with promising results. In human studies, although probiotics were effective in ameliorating seroconversion to vaccines for influenza, rotavirus and other micro-organisms, the results for clinical use are still controversial, especially in particular settings, such as during the last trimester of pregnancy.

CONCLUSION

Although this topic remains controversial, the use of probiotics as adjuvant factors in vaccination represents a strategic key for different applications. The available data are deeply influenced by heterogeneity among studies in terms of strains, timing and duration of administration, and patients. Although these do not allow us to draw definitive conclusions, probiotics as adjuvants in vaccination should be considered in future studies, especially in the elderly and in children, where vaccine effectiveness and duration of immunization really matter.

Serum cytokine patterns are modulated in infants fed formula with probiotics or milk fat globule membranes: A randomized controlled trial

Background

Proteins and lipids of milk fat globule membrane (MFGM) and probiotics are immunomodulatory. We hypothesized that Lactobacillus paracasei ssp. paracasei strain F19 (F19) would augment vaccine antibody and T helper 1 type immune responses whereas MFGM would produce an immune response closer to that of breastfed (BF) infants.

Objective

To compare the effects of supplementing formula with F19 or bovine MFGM on serum cytokine and vaccine responses of formula-fed (FF) and BF infants.

Design

FF infants were randomized to formula with F19 (n = 195) or MFGM (n = 192), or standard formula (SF) (n = 194) from age 21±7 days until 4 months. A BF group served as reference (n = 208). We analyzed seven cytokines (n = 398) in serum at age 4 months using magnetic bead-based multiplex technology. Using ELISA, we analyzed anti-diphtheria IgG (n = 258) and anti-poliovirus IgG (n = 309) concentrations in serum before and after the second and third immunization, respectively.

Results

Compared with SF, the F19 group had greater IL-2 and lower IFN-γ concentrations (p<0.05, average effect size 0.14 and 0.39). Compared with BF, the F19 group had greater IL-2, IL-4 and IL-17A concentrations (p<0.05, average effect size 0.42, 0.34 and 0.26, respectively). The MFGM group had lower IL-2 and IL-17A concentrations compared with SF (p<0.05, average effect size 0.34 and 0.31). Cytokine concentrations were comparable among the MFGM and BF groups. Vaccine responses were comparable among the formula groups.

Conclusions

Contrary to previous studies F19 increased IL-2 and lowered IFN-γ production, suggesting that the response to probiotics differs across populations. The cytokine profile of the MFGM group approached that of BF infants, and may be associated with the previous finding that infectious outcomes for the MFGM group in this cohort were closer to those of BF infants, as opposed to the SF group. These immunomodulatory effects support future clinical evaluation of infant formula with F19 or MFGM.

Vaccine Interactions With the Infant Microbiome: Do They Define Health and Disease?

Over the past decade, there has been a growing awareness of the vital role of the microbiome in the function of the immune system. Recently, several studies have demonstrated a relationship between the composition of the microbiome and the vaccine-specific immune response. As a result of these findings, the administration of probiotics has been proposed as a means of boosting vaccine-specific immunity. Early results have so far been highly inconsistent, with little evidence of sustained benefit. To date, a precise determination of the aspects of the microbiome that impact immunity is still lacking, and the mechanisms of action are also unknown. Further investigations into these questions are necessary to effectively manipulate the microbiome for the purpose of boosting immunity and enhancing vaccine-specific responses in infants. In this review, we summarize recent studies aimed at altering the neonatal gut microbiome to enhance vaccine responses and highlight gaps in knowledge and understanding. We also discuss research strategies aimed at filling these gaps and developing potential therapeutic interventions.

Effects of non-pharmacological interventions as vaccine adjuvants in humans: a systematic review and network meta-analysis

INTRODUCTION

Psychological and behavioural may enhance vaccine effectiveness. We conducted a systematic review and network meta-analysis (NMA) to examine the effects of non-pharmacological adjuvants on vaccine effectiveness, as measured by antibody responses to vaccination.

AREAS COVERED

Electronic databases (EMBASE, Medline, PsychINFO, CINAHL) were searched from inception to 6th February 2018. This yielded 100 eligible papers, reporting 106 trials: 79 interventions associated with diet and/or nutrition; 12 physical activity interventions and 9 psychological interventions.Over half (58/106) of trials reported evidence of an enhanced antibody response to vaccination across one or more outcomes. The NMA considered the comparative effects between all intervention types, control and placebo for antibody titres (48 studies), seroconversion (25 studies) and seroprotection (23 studies) separately. The NMA provided weak evidence in support of nutritional formulae and probiotics in increasing antibody titres.

EXPERT OPINION

This review offers a comprehensive summary of the literature on non-pharmacological interventions as vaccine adjuvants. The evidence is characterised by considerable heterogeneity but provides early evidence in support of nutritional formulae and probiotic interventions. Psychological and exercise-based interventions were characterised by limited and unreliable evidence. Large, well-designed studies including consistent core outcomes and measures of intervention adherence and fidelity are required.

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.

Immune modulatory capacity of probiotic lactic acid bacteria and applications in vaccine development

Vaccination is one of the most important prevention tools providing protection against infectious diseases especially in children below the age of five. According to estimates, more than 5 million lives are saved annually by the implementation of six standard vaccines, including diphtheria, hepatitis B, Haemophilus influenza type b, polio, tetanus and yellow fever. Despite these efforts, we are faced with challenges in developing countries where increasing population and increasing disease burden and difficulties in vaccine coverage and delivery cause significant morbidity and mortality. Additionally, the high cost of these vaccines is also one of the causes for inappropriate and inadequate vaccinations in these regions. Thus, developing cost-effective vaccine strategies that could provide a stronger immune response with reduced vaccination schedules and maximum coverage is of critical importance. In last decade, different approaches have been investigated; among which live bacterial vaccines have been the focus of attention. In this regard, probiotic lactic acid bacteria have been extensively studied as safe and effective vaccine candidates. These microorganisms represent the largest group of probiotic bacteria in the intestine and are generally recognised as safe (GRAS) bacteria. They have also attracted attention due to their immunomodulatory actions and their effective role as novel vaccine adjuvants. A significant property of these bacteria is their ability to mimic natural infections, while intrinsically possessing mucosal adjuvant properties. Additionally, as live bacterial vaccines are administered orally or nasally, they have higher acceptance and better safety, but also avoid the risk of contamination due to needles and syringes. In this review, we emphasise the role of probiotic Lactobacillus strains as putative oral vaccine carriers and novel vaccine adjuvants.

How the gut microbiome regulates host immune responses to viral vaccines

The co-evolution of the microbiota and immune system has forged a mutually beneficial relationship. This relationship allows the host to maintain the balance between active immunity to pathogens and vaccines and tolerance to self-antigens and food antigens. In children living in low-income and middle-income countries, undernourishment and repetitive gastrointestinal infections are associated with the failure of oral vaccines. Intestinal dysbiosis associated with these environmental influences, as well as some host-related factors, compromises immune responses and negatively impacts vaccine efficacy. To understand how immune responses to viral vaccines can be optimally modulated, mechanistic studies of the relationship between the microbiome, host genetics, viral infections and the development and function of the immune system are needed. We discuss the potential role of the microbiome in modulating vaccine responses in the context of a growing understanding of the relationship between the gastrointestinal microbiota, host related factors (including histo-blood group antigens) and resident immune cell populations.

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.

Factors That Influence the Immune Response to Vaccination

There is substantial variation between individuals in the immune response to vaccination. In this review, we provide an overview of the plethora of studies that have investigated factors that influence humoral and cellular vaccine responses in humans. These include intrinsic host factors (such as age, sex, genetics, and comorbidities), perinatal factors (such as gestational age, birth weight, feeding method, and maternal factors), and extrinsic factors (such as preexisting immunity, microbiota, infections, and antibiotics). Further, environmental factors (such as geographic location, season, family size, and toxins), behavioral factors (such as smoking, alcohol consumption, exercise, and sleep), and nutritional factors (such as body mass index, micronutrients, and enteropathy) also influence how individuals respond to vaccines. Moreover, vaccine factors (such as vaccine type, product, adjuvant, and dose) and administration factors (schedule, site, route, time of vaccination, and coadministered vaccines and other drugs) are also important. An understanding of all these factors and their impacts in the design of vaccine studies and decisions on vaccination schedules offers ways to improve vaccine immunogenicity and efficacy.

Feeding Infants Formula With Probiotics or Milk Fat Globule Membrane: A Double-Blind, Randomized Controlled Trial

Purpose: To evaluate effects on growth and infection rates of supplementing infant formula with the probiotic Lactobacillus paracasei ssp. paracasei strain F19 (F19) or bovine milk fat globule membrane (MFGM). Methods: In a double-blind, randomized controlled trial, 600 infants were randomized to a formula supplemented with F19 or MFGM, or to standard formula (SF). A breastfed group was recruited as reference (n = 200).The intervention lasted from age 21 ± 7 days until 4 months, and infants were followed until age one year. Results: Both experimental formulas were well tolerated and resulted in high compliance. The few reported adverse events were not likely related to formula, with the highest rates in the SF group, significantly higher than for the F19-supplemented infants (p = 0.046). Weight or length gain did not differ during or after the intervention among the formula-fed groups, with satisfactory growth. During the intervention, overall, the experimental formula groups did not have more episodes of diarrhea, fever, or days with fever than the breastfed infants. However, compared to the breastfed infants, the SF group had more fever episodes (p = 0.021) and days with fever (p = 0.036), but not diarrhea. Compared with the breastfed group, the F19-supplemented infants but not the other two formula groups had more visits/unscheduled hospitalizations (p = 0.015) and borderline more episodes of upper respiratory tract infections (p = 0.048). Conclusions: Both the MFGM- and F19-supplemented formulas were safe and well-tolerated, leading to few adverse effects, similar to the breastfed group and unlike the SF group. During the intervention, the MFGM-supplemented infants did not differ from the breastfed infants in any primary outcome.

Temporal and long-term gut microbiota variation in allergic disease: A prospective study from infancy to school age

BACKGROUND

Compositional changes in the early-life gut microbiota have been implicated in IgE-associated allergic diseases, but there is lack of longitudinal studies. We examined gut microbiota development from infancy to school age in relation to onset of IgE-associated allergic diseases. At 8 years of age, we also examined the relationship between gut microbiota and T-cell regulation, estimated as responses to polyclonal T-cell activation.

METHODS

Stool samples were collected from 93 children at 4, 6, 13 months, and 8 years of age. The gut microbiota was profiled using 16S rRNA gene sequencing. Peripheral blood was drawn from all children, and mononuclear cells were polyclonally activated. Levels of IL-10 and FOXP3 mRNA copies were determined using real-time quantitative reverse transcriptase-PCR.

RESULTS

At 8 years of age, 21 children were diagnosed with IgE-associated allergic disease and 90% displayed allergic comorbidity. Seventy-two children were nonallergic and nonsensitized. Statistical tests with multiple testing corrections demonstrated temporal underrepresentation of Ruminococcus and consistent underrepresentation of Bacteroides, Prevotella, and Coprococcus in allergic compared to nonallergic children from infancy to school age. The gut microbiota of the allergic 8-year-olds was enriched in Bifidobacterium and depleted of Lactobacillus, Enterococcus, and Lachnospira. In allergic 8-year-olds, Faecalibacterium correlated with IL-10 mRNA levels (r_s  = 0.49_, P_adj  = 0.02) with the same trend for FOXP3 (r_s  = 0.39_, P_adj  = 0.08).

CONCLUSIONS

We identified both temporal and long-term variation in the differential abundance of specific bacterial genera in children developing IgE-associated allergic disease. Improved dietary interventions aiming at expanding immune-modulatory taxa could be studied for prevention of allergic disease.

Probiotics and the immunological response to infant vaccinations; a double-blind randomized controlled trial

OBJECTIVES

To examine the effect of a combination of probiotics on the antibody response to pneumococcal and pertussis vaccination in healthy Danish children, aged 8-14 months, at the time of starting day care. Moreover, the cytokine response to lipopolysaccharide of whole blood was assessed.

METHODS

A total of 290 children were randomly allocated to receive a combination of Bifidobacterium animalis ssp. lactis and Lactobacillus rhamnosus GG daily for a 6-month intervention period, and blood samples were drawn at the start and end of the study. Specific antibody response towards Streptococcus pneumoniae serotypes and Bordetella pertussis toxin, as well as endotoxin-induced interleukin-6 (IL-6) and interferon-γ (IFN-γ) production in blood were analysed by Luminex and ELISA.

RESULTS

There was no significant difference between the average individual changes from baseline to end of study in antibody concentrations for S. pneumoniae for both the probiotics (340.4% ± 11.2%) and the placebo group (382.9% ± 10.4%) (p 0.525), nor for B. pertussis toxin in the two groups (probiotics 190.1% ± 12.6% versus placebo 238.8% ± 1.1%, p 0.340). The average individual change in IL-6 concentration was significantly lower in the probiotics versus the placebo group (2.9% ± 10.3% versus 33.7% ± 9.0%, p 0.024), whereas there was no difference in IFN-γ concentration (0.0% ± 0.2% versus -0.2% ± 0.1%, p 0.279).

CONCLUSIONS

The probiotic intervention did not affect the antibody response against S. pneumoniae and B. pertussis toxin in healthy Danish children.

Pre-protective effects of dietary chitosan supplementation against oxidative stress induced by diquat in weaned piglets

The protective effects of chitosan (CS) supplementations on oxidative stress induced by diquat in weaned piglets were investigated. A total of 36 crossbreed piglets with an average live body weight (BW) of 8.80 ± 0.53 kg were weaned at 28 ± 2 days and randomly divided into six dietary treatments (n = 6): control (basal diet), negative control (10 mg diquat/kg BW injected to piglets fed with basal diet), and basal diet treatments containing either 250, 500, 1000, or 2000 mg/kg of CS administered to piglets injected with 10 mg diquat/kg BW. The experiment conducted for 21 days which consisted of pre-starter period (14 days) and starter period (7 days). BW, feed intake, and fecal consistency were monitored. Blood samples were collected to determine antioxidative and immune parameters. CS supplementation improved the growth performance and decreased fecal score of piglets from days 1 to 14. Diquat also induced oxidative stress and inflammatory responses by decreasing the activities of antioxidant and regulating cytokines. But dietary CS alleviated these negative effects induced by diquat that showed decreasing serum concentrations of pro-inflammatory cytokines but increasing activities of antioxidant enzymes and anti-inflammatory cytokines. Results indicated that CS attenuated the oxidative stress of piglets caused by diquat injection.

Pre- and probiotics for allergy prevention: time to revisit recommendations?

Reduced intensity and diversity of microbial exposure is considered a major factor driving abnormal postnatal immune maturation and increasing allergy prevalence, particularly in more affluent regions. Quantitatively, the largest important source of early immune-microbial interaction, the gut microbiota, is of particular interest in this context, with variations in composition and diversity in the first months of life associated with subsequent allergy development. Attempting to restore the health consequences of the 'dysbiotic drift' in modern society, interventions modulating gut microbiota for allergy prevention have been evaluated in several randomized placebo-controlled trials. In this review, we provide an overview of these trials and discuss recommendations from international expert bodies regarding prebiotic, probiotic and synbiotic interventions. Recent guidelines from the World Allergy Organization recommend the use of probiotics for the primary prevention of eczema in pregnant and breastfeeding mothers of infants at high risk for developing allergy and in high-risk infants. It is however stressed that these recommendations are conditional, based on very low-quality evidence and great heterogeneity between studies, which also impedes specific and practical advice to consumers on the most effective regimens. We discuss how the choice of probiotic strains, timing and duration of administration can critically influence the outcome due to different effects on immune modulation and gut microbiota composition. Furthermore, we propose strategies to potentially improve allergy-preventive effects and enable future evidence-based implementation.

Adjuvant Probiotics and the Intestinal Microbiome: Enhancing Vaccines and Immunotherapy Outcomes

Immune defence against pathogenic agents comprises the basic premise for the administration of vaccines. Vaccinations have hence prevented millions of infectious illnesses, hospitalizations and mortality. Acquired immunity comprises antibody and cell mediated responses and is characterized by its specificity and memory. Along a similar congruent yet diverse mode of disease prevention, the human host has negotiated from in utero and at birth with the intestinal commensal bacterial cohort to maintain local homeostasis in order to achieve immunological tolerance in the new born. The advent of the Human Microbiome Project has redefined an appreciation of the interactions between the host and bacteria in the intestines from one of a collection of toxic waste to one of a symbiotic existence. Probiotics comprise bacterial genera thought to provide a health benefit to the host. The intestinal microbiota has profound effects on local and extra-intestinal end organ physiology. As such, we further posit that the adjuvant administration of dedicated probiotic formulations can encourage the intestinal commensal cohort to beneficially participate in the intestinal microbiome-intestinal epithelia-innate-cell mediated immunity axes and cell mediated cellular immunity with vaccines aimed at preventing infectious diseases whilst conserving immunological tolerance. The strength of evidence for the positive effect of probiotic administration on acquired immune responses has come from various studies with viral and bacterial vaccines. We posit that the introduction early of probiotics may provide significant beneficial immune outcomes in neonates prior to commencing a vaccination schedule or in elderly adults prior to the administration of vaccinations against influenza viruses.

Bugging allergy; role of pre-, pro- and synbiotics in allergy prevention

Large-scale biodiversity loss and complex changes in social behaviors are altering human microbial ecology. This is increasingly implicated in the global rise in inflammatory diseases, most notably the "allergy epidemic" in very early life. Colonization of human ecological niches, particularly the gastrointestinal tract, is critical for normal local and systemic immune development and regulation. Disturbances in composition, diversity and timing of microbial colonization have been associated with increased allergy risk, indicating the importance of strategies to restore a dysbiotic gut microbiota in the primary prevention of allergic diseases, including the administration of probiotics, prebiotics and synbiotics. Here, we summarize and discuss findings of randomized clinical trials that have examined the effects of these microbiome-related strategies on short and long-term allergy preventative effects - including new guidelines from the World Allergy Organization which now recommend probiotics and prebiotics for allergy prevention under certain conditions. The relatively low quality evidence, limited comparative studies and large heterogeneity between studies, have collectively hampered recommendations on specific probiotic strains, specific timing and specific conditions for the most effective preventive management. At the same time the risk of using available products is low. While further research is needed before specific practice guidelines on supplement probiotics and prebiotics, it is equally important that the underlying dietary and lifestyle factors of dysbiosis are addressed at both the individual and societal levels.

Can probiotics enhance vaccine-specific immunity in children and adults?

The growing use of probiotics by the general public has heightened the interest in understanding the role of probiotics in promoting health and preventing disease. General practitioners and specialists often receive inquiries from their patients regarding probiotic products and their use to ward off systemic infection or intestinal maladies. Enhanced immune function is among the touted health benefits conferred by probiotics but has not yet been fully established. Results from recent clinical trials in adults suggest a potential role for probiotics in enhancing vaccine-specific immunity. Although almost all vaccinations are given during infancy and childhood, the numbers of and results from studies using probiotics in pediatric subjects are limited. This review evaluates recent clinical trials of probiotics used to enhance vaccine-specific immune responses in adults and infants. We highlight meaningful results and the implications of these findings for designing translational and clinical studies that will evaluate the potential clinical role for probiotics. We conclude that the touted health claims of probiotics for use in children to augment immunity warrant further investigation. In order to achieve this goal, a consensus should be reached on common study designs that apply similar treatment timelines, compare well-characterised probiotic strains and monitor effective responses against different classes of vaccines.

Probiotics, antibiotics and the immune responses to vaccines

Orally delivered vaccines have been shown to perform poorly in developing countries. There are marked differences in the structure and the luminal environment of the gut in developing countries resulting in changes in immune and barrier function. Recent studies using newly developed technology and analytic methods have made it increasingly clear that the intestinal microbiota activate a multitude of pathways that control innate and adaptive immunity in the gut. Several hypotheses have been proposed for the underperformance of oral vaccines in developing countries, and modulation of the intestinal microbiota is now being tested in human clinical trials. Supplementation with specific strains of probiotics has been shown to have modulatory effects on intestinal and systemic immune responses in animal models and forms the basis for human studies with vaccines. However, most studies published so far that have evaluated the immune response to vaccines in children and adults have been small and results have varied by age, antigen, type of antibody response and probiotic strain. Use of anthelminthic drugs in children has been shown to possibly increase immunogenicity following oral cholera vaccination, lending further support to the rationale for modulation of the immune response to oral vaccination through the intestinal microbiome.

Microbiota manipulation for weight change

Manipulation of the intestinal microbiota has been linked to weight changes and obesity. To explore the influence of specific agents that alter the intestinal flora on weight in different patient groups we conducted a meta-analysis of randomized controlled trials (RCTs) reporting on the effects of probiotics, prebiotics, synbiotics, and antibiotics on weight. We searched the Pubmed and Cochrane Library databases for trials on adults, children, and infants evaluating the effects of these substances on weight. Our primary outcome was weight change from baseline. Standardized mean differences (SMDs) with 95% confidence intervals were calculated. We identified and included 13 adult, 17 children, and 23 infant RCTs. Effects were opposite among adults and children, showing weight loss among adults (SMD -0.54 [-0.83, -0.25)) and minor weight gains among children (SMD 0.20 [0.04, 0.36]) and infants (SMD 0.30 [-0.01, 0.62]) taking mainly Lactobacillus probiotic supplements. Heterogeneity was substantial in the adult and infant analyses and could not be explained by intervention or patient characteristics. Azithromycin administration in children with pulmonary disease was associated with weight gain (SMD 0.39 [0.24, 0.54]), without heterogeneity. A high risk of selective reporting and attrition bias was detected across the studies, making it difficult to draw firm conclusions. Overall, our meta-analysis suggests that there may be a role for probiotics in promoting weight loss in adults and weight gain in children, however additional studies are needed. Though we cannot recommend antibiotic administration for weight manipulation, its use provides advantageous weight gain in children with cystic fibrosis and bronchiectasis.

Immune system stimulation by probiotic microorganisms

Probiotic organisms are claimed to offer several functional properties including stimulation of immune system. This review is presented to provide detailed informations about how probiotics stimulate our immune system. Lactobacillus rhamnosus GG, Lactobacillus casei Shirota, Bifidobacterium animalis Bb-12, Lactobacillus johnsonii La1, Bifidobacterium lactis DR10, and Saccharomyces cerevisiae boulardii are the most investigated probiotic cultures for their immunomodulation properties. Probiotics can enhance nonspecific cellular immune response characterized by activation of macrophages, natural killer (NK) cells, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in strain-specific and dose-dependent manner. Mixture and type (gram-positive and gram-negative) of probiotic organisms may induce different cytokine responses. Supplementation of probiotic organisms in infancy could help prevent immune-mediated diseases in childhood, whereas their intervention in pregnancy could affect fetal immune parameters, such as cord blood interferon (IFN)-γ levels, transforming growth factor (TGF)-β1 levels, and breast milk immunoglobulin (Ig)A. Probiotics that can be delivered via fermented milk or yogurt could improve the gut mucosal immune system by increasing the number of IgA(+) cells and cytokine-producing cells in the effector site of the intestine.

Adjuvant effects of L. acidophilus LW1 on immune responses to the foot-and-mouth disease virus DNA vaccine in mice

The adjuvant effects of Lactobacillus acidophilus on DNA vaccination are not fully understood. It has been hypothesized that swine-derived Lactobacillus acidophilus SW1 (LASW1) could function as an immune adjuvant to enhance antigen-specific immune responses after foot-and-mouth disease (FMD) DNA vaccination in mice. To evaluate the effect of oral LASW1 on the immune response to a DNA vaccine (pRC/CMV-vp1) harboring FMD VP1 gene, anti-FMDV antibody and its isotypes, T-cell proliferation, and cytokine detection were investigated. The results showed that LASW1 was able to enhance FMDV-specific antibody levels and FMDV-neutralizing antibodies. After a booster vaccine, the anti-FMDV antibody titers and FMDV-neutralizing antibodies levels induced by pRC/CMV-vp1 were higher in mice treated with LSAW1 than in the group immunized with pRC/CMV-vp1 alone (the control). Using T-cell proliferation, the stimulation index of the LASW1 group was significantly higher in response to ConA and 146S antigen (P<0.05) than in the control group. Importantly, higher concentrations of IFN-γ and IFN-γ-producing cells were also observed in splenocytes isolated from the experimental LASW1 mice, indicating that INF-γ secretion is important to the immune response to LASW1. The results indicate that LASW1 is a promising immune adjuvant in DNA vaccination against FMD when administrated orally.

Probiotics during weaning: a follow-up study on effects on body composition and metabolic markers at school age

PURPOSE

An aberrant gut microbiome has been suggested to contribute to the worldwide epidemic of obesity. In animal models, the probiotic Lactobacillus paracasei ssp. paracasei F19 (LF19) induced upregulation of genes involved in energy homoeostasis, reduced body fat and altered the serum (S) lipoprotein profile. In our previous report, feeding LF19 to infants during weaning impacted the global plasma metabolome. LF19 lowered palmitoleic acid, a monounsaturated fatty acid associated with hypertriglyceridemia and increased visceral adiposity. Therefore, we assessed if feeding LF19 from 4 to 13 months of age would have long-term effects on body composition, growth and metabolic markers.

METHODS

Of 179 children included in our baseline study, 120 entered the follow-up at 8-9 years of age, n = 58 in the probiotic and n = 62 in the placebo group. Body composition was measured using dual energy X-ray absorptiometry. Anthropometrics of the child and accompanying parent(s) were assessed. S-lipids, insulin, glucose and transaminases were determined after overnight fasting.

RESULTS

LF19 did not affect body mass index z-score, sagittal abdominal diameter, fat-free mass, fat mass index, truncal fat %, android or gynoid fat % and had no long-term impact on any of the assessed metabolic markers (p > 0.05).

CONCLUSION

Feeding LF19 during infancy did not modulate body composition, growth or any of the assessed metabolic markers at school age. The steady increase in probiotic products targeting infants and children calls for long-term follow-up of initiated probiotic intervention studies.

Probiotic and synbiotic safety in infants under two years of age

In this study, we systematically evaluated safety aspects in clinical trials with probiotics and synbiotics in young infants (0-2 years of age). This study is an update of earlier reports and covers the recent literature from 2008-2013. The safety evaluation is performed along the Common Terminology Clinical Adverse Events (CTCAE) version 4.0 scale, hereby also providing guidance for future studies. Safety aspects are represented and related to number of participants per probiotic strain/culture, study duration, dosage, clinical condition and selected afflictions. The results show a deficiency in the precise reporting and classification of adverse events in most studies. Analysis of 57 clinical trials with probiotics and synbiotics in combination with eight follow-up studies indicate that probiotic administration to infants between 0 and 24 months is safe with regard to the evaluated strains in infants with a particular health status or susceptibility. Most adverse events and serious adverse events were considered unrelated to the study product, and there were no major safety concerns. Almost all studies concluded that none of the adverse effects were related to the study product; the study products are generally well tolerated. Finally, inconsistent, imprecise and potentially incomplete reporting as well as the variation in probiotic strains, dosages, administration regimes, study populations and reported outcomes, greatly limit the generalizability of conclusions and argue convincingly for obligatory and standardised behaviour on adverse events (CTCAE) reporting in ‘food’ studies.

Probiotic supplementation during pregnancy or infancy for the prevention of asthma and wheeze: systematic review and meta-analysis

OBJECTIVE

To evaluate the association of probiotic supplementation during pregnancy or infancy with childhood asthma and wheeze.

DESIGN

Systematic review and meta-analysis of randomised controlled trials.

DATA SOURCES

Medline, Embase, and Central (Cochrane Library) databases from inception to August 2013, plus the World Health Organization's international clinical trials registry platform and relevant conference proceedings for the preceding five years. Included trials and relevant reviews were forward searched in Web of Science.

REVIEW METHODS

Two reviewers independently identified randomised controlled trials evaluating probiotics administered to mothers during pregnancy or to infants during the first year of life. The primary outcome was doctor diagnosed asthma; secondary outcomes included wheeze and lower respiratory tract infection.

RESULTS

We identified 20 eligible trials including 4866 children. Trials were heterogeneous in the type and duration of probiotic supplementation, and duration of follow-up. Only five trials conducted follow-up beyond participants' age of 6 years (median 24 months), and none were powered to detect asthma as the primary outcome. The overall rate of doctor diagnosed asthma was 10.7%; overall rates of incident wheeze and lower respiratory tract infection were 33.3% and 13.9%, respectively. Among 3257 infants enrolled in nine trials contributing asthma data, the risk ratio of doctor diagnosed asthma in participants randomised to receive probiotics was 0.99 (95% confidence interval 0.81 to 1.21, I(2)=0%). The risk ratio of incident wheeze was 0.97 (0.87 to 1.09, I(2)=0%, 9 trials, 1949 infants). Among 1364 infants enrolled in six trials, the risk ratio of lower respiratory tract infection after probiotic supplementation was 1.26 (0.99 to 1.61, I(2)=0%). We adjudicated most trials to be of high (ten trials) or unclear (nine trials) risk of bias, mainly due to attrition.

CONCLUSIONS

We found no evidence to support a protective association between perinatal use of probiotics and doctor diagnosed asthma or childhood wheeze. Randomised controlled trials to date have not yielded sufficient evidence to recommend probiotics for the primary prevention of these disorders. Extended follow-up of existing trials, along with further clinical and basic research, are needed to accurately define the role of probiotics in the prevention of childhood asthma.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42013004385).

Microbiome, sex hormones, and immune responses in the reproductive tract: challenges for vaccine development against sexually transmitted infections

The female and male reproductive tracts are complex eco-systems where immune cells, hormones, and microorganisms interact. The characteristics of the reproductive tract mucosa are distinct from other mucosal sites. Reproductive tract mucosal immune responses are compartmentalized, unique, and affected by resident bacterial communities and sex hormones. The female and male genital microbiomes are complex environments that fluctuate in response to external and host-associated stimuli. The female vaginal microbiota play an important role in preventing colonization by pathogenic organisms. Sex hormones and their duration of exposure affect the composition and stability of the microbiome as well as systemic and mucosal immune responses. In addition to the characteristics of the pathogen they are targeting, successful vaccines against sexually transmitted pathogens must take into account the differences between the systemic and mucosal immune responses, the compartmentalization of the mucosal immune responses, the unique characteristics of the reproductive tract mucosa, the role of the mucosal bacterial communities, the impact of sex hormones, and the interactions among all of these factors.

Modulation of vaccine response by concomitant probiotic administration

Evidence suggests that probiotic bacteria modulate both innate and adaptive immunity in the host, and in some situations can result in reduced severity of common illnesses, such as acute rotavirus infection and respiratory infections. Responses to vaccination are increasingly being used to provide high quality information on the immunomodulatory effects of dietary components in humans. The present review focuses on the effect of probiotic administration upon vaccination response. The majority of studies investigating the impact of probiotics on responses to vaccination have been conducted in healthy adults, and at best they show modest effects of probiotics on serum or salivary IgA titres. Studies in infants and in elderly subjects are very limited, and it is too early to draw any firm conclusions regarding the potential for probiotics to act as adjuvants in vaccination. Although some studies are comparable in terms of duration of the intervention, age and characteristics of the subjects, most differ in terms of the probiotic selected. Further well designed, randomized, placebo-controlled studies are needed to understand fully the immunomodulatory properties of probiotics, whether the effects exerted are strain-dependent and age-dependent and their clinical relevance in enhancing immune protection following vaccination.

Probiotics in primary prevention of allergic disease--follow-up at 8-9 years of age

BACKGROUND

Long-term effects of probiotics in primary prevention of allergic disease need further evaluation. We previously reported a reduced cumulative incidence of infant eczema by feeding Lactobacillus paracasei ssp paracasei F19 (LF19) during weaning. Therefore, we assessed effects of LF19 on the prevalence of allergic disease at school age.

METHODS

In a double-blind placebo-controlled trial infants were randomized to daily intake of cereals with (n = 89) or without LF19 10(8) CFU (n = 90) from 4-13 months of age. At age 8-9, we evaluated the prevalence of allergic disease (eczema, allergic rhinitis, asthma, and food allergy) by clinical examination and validated questionnaires. IgE sensitization was assessed by skin prick test (inhalant allergens) and specific IgE levels (food allergens). Lung function was evaluated by a spirometry reversibility test. Fractional exhaled nitric oxide (FENO ) was measured.

RESULTS

Of 171 children that completed the intervention, 121 were assessed at age 8-9. In the probiotic group, 15/59 (25%) were diagnosed with any allergic disease vs 22/62 (35%) in the placebo group [OR (95% CI) 0.62 (0.28-1.36)]. Corresponding numbers for IgE-associated allergic disease were 9/53 (17%) vs 12/59 (20%) [0.80 (0.31-2.09)]. Median (25th-75th percentile) FENO was 9 (8-12) in the probiotic vs 8 (7-12) ppb in the placebo group (P > 0.05). There was no effect of LF19 on lung function measures (P > 0.05).

CONCLUSIONS

There was no long-term effect of LF19 on any diagnosed allergic disease, airway inflammation or IgE sensitization. This suggests delayed eczema onset but to fully examine long-term benefits a larger study population had been needed.

Early intervention with probiotic Lactobacillus paracasei F19 has no long-term effect on caries experience

The aim of the study was to evaluate possible long-term effects of a cereal diet supplemented with Lactobacillus paracasei F19 (LF19) during weaning on caries experience, mutans streptococci (MS) and lactobacilli (LBC) in a group of 9-year-old children. A secondary aim was to evaluate if the intervention resulted in the permanent integration of LF19 as part of the oral microbiota. The study followed up on a double-blind placebo-controlled randomised trial. Among 179 infants that were randomised to a daily diet that included cereals with or without LF19 from 4 to 13 months of age, 56 from the probiotic group and 62 from the placebo group participated in the follow-up at 9 years. Data were collected by oral clinical examination and questionnaires. MS and LBC levels were assessed with conventional cultivation; LF19 was detected by using randomly amplified polymerase chain reactions (RAPD-PCR). At the follow-up, neither decayed, missing and filled surfaces for primary teeth (dmfs) nor decayed, missing and filled surfaces for permanent teeth (DMFS) differed significantly between the probiotic and placebo groups (p > 0.05). MS and LBC levels were similar in both groups (p > 0.05). RAPD-PCR showed no evidence of oral colonisation with LF19 in the study group. It is concluded that an early intervention with LF19 did not affect the frequency of dental caries, MS or LBC. LF19 did not establish itself as a permanent facet of the oral microbiota in any of the subjects included in this study.

Dietary supplementation with Lactobacillus fermentum I5007 improves the anti-oxidative activity of weanling piglets challenged with diquat

AIMS

To determine the effects of Lactobacillus fermentum I5007 on the redox state of piglets oxidatively stressed with diquat.

METHODS AND RESULTS

Twenty-four, 28-day-old barrows were used in a 2 × 2 factorial design experiment with the main effects being Lact. fermentum supplementation and diquat challenge. Half of the pigs (n = 12) were orally administered with 20 ml of a solution containing 10(8 ) CFU ml(-1) of Lact. fermentum each morning of the 21-day trial, while the remainder received saline. On day 8, these two groups were further subdivided so that half of the pigs in each group (n = 6) were intraperitoneally injected with 10 mg kg(-1) BW diquat, while the remainder received saline. The diquat-injected pigs had significantly poorer performance and increased levels of plasma cortisol, adrenaline, carbonyl and malondialdehyde. Lactobacillus fermentum supplementation significantly increased superoxide dismutase and glutathione and increased the ability to inhibit superoxide anion production in liver and muscle.

CONCLUSIONS

Lactobacillus fermentum improved the anti-oxidative defence system and alleviated damage caused by diquat.

SIGNIFICANCE AND IMPACT OF THE STUDY

Lactobacillus fermentum has the potential to alleviate oxidative stress and improve weaning pig performance.

Probiotics and colostrum/milk differentially affect neonatal humoral immune responses to oral rotavirus vaccine

Breast milk (colostrum [col]/milk) components and gut commensals play important roles in neonatal immune maturation, establishment of gut homeostasis and immune responses to enteric pathogens and oral vaccines. We investigated the impact of colonization by probiotics, Lactobacillus rhamnosus GG (LGG) and Bifidobacterium lactis Bb12 (Bb12) with/without col/milk (mimicking breast/formula fed infants) on B lymphocyte responses to an attenuated (Att) human rotavirus (HRV) Wa strain vaccine in a neonatal gnotobiotic pig model. Col/milk did not affect probiotic colonization in AttHRV vaccinated pigs. However, unvaccinated pigs fed col/milk shed higher numbers of probiotic bacteria in feces than non-col/milk fed colonized controls. In AttHRV vaccinated pigs, col/milk feeding with probiotic treatment resulted in higher mean serum IgA HRV antibody titers and intestinal IgA antibody secreting cell (ASC) numbers compared to col/milk fed, non-colonized vaccinated pigs. In vaccinated pigs without col/milk, probiotic colonization did not affect IgA HRV antibody titers, but serum IgG HRV antibody titers and gut IgG ASC numbers were lower, suggesting that certain probiotics differentially impact HRV vaccine responses. Our findings suggest that col/milk components (soluble mediators) affect initial probiotic colonization, and together, they modulate neonatal antibody responses to oral AttHRV vaccine in complex ways.

Impact of probiotic feeding during weaning on the serum lipid profile and plasma metabolome in infants

The gut microbiome interacts with the host in the metabolic response to diet, and early microbial aberrancies may be linked to the development of obesity and metabolic disorders later in life. Probiotics have been proposed to affect metabolic programming and blood lipid levels, although studies are lacking in infants. Here, we report on the lipid profile and global metabolic response following daily feeding of probiotics during weaning. A total of 179 healthy, term infants were randomised to daily intake of cereals with (n89) or without (n90) the addition ofLactobacillus paracaseissp.paracaseiF19 (LF19) 108colony-forming units per serving from 4 to 13 months of age. Weight, length and skinfold thickness were monitored. Venous blood was drawn at 5·5 and 13 months of age for analysis of the serum lipid profile. In a subsample, randomly selected from each group, GC-time-of-flight/MS was used to metabolically characterise plasma samples from thirty-seven infants. A combination of multi- and univariate analysis was applied to reveal differences related to LF19 treatment based on 228 putative metabolites, of which ninety-nine were identified or classified. We observed no effects of probiotic feeding on anthropometrics or the serum lipid profile. However, we detected significantly lower levels of palmitoleic acid (16 : 1) (P< 0·05) and significantly higher levels of putrescine (P< 0·01) in LF19-treated infants. Palmitoleic acid is a major MUFA strongly linked to visceral obesity, while putrescine is a polyamine with importance for gut integrity. Whether the observed differences will have long-term health consequences are being followed.

Diverse microbial exposure - consequences for vaccine development

Numerous epidemiological studies suggest that there is an inverse relationship between "immunologically mediated diseases of affluence", such as allergy, diabetes and inflammatory bowel disease on one hand and few infections encountered in early childhood, on the other hand. Careful analysis of the epidemiological, clinical and animal studies taken together, however, suggests that the protection is mediated by broad exposure to a wealth of commensal, non-pathogenic microorganisms early in life, rather than by infections. Microbial exposure has little relationship with "hygiene" in the usual meaning of the word and the term "hygiene hypothesis" is therefore misleading. A better term would be "microbial deprivation hypothesis". The suggestion that childhood infections would protect against allergic disease led to unfortunate speculations that vaccinations would increase the risk for allergies and diabetes. Numerous epidemiological studies have therefore been conducted, searching for a possible relationship between various childhood vaccinations on one hand and allergy on the other hand. It is reasonable from these studies to conclude that vaccinations against infectious agents neither significantly increase, nor reduce the likelihood of immunologically mediated diseases. It is established that the postnatal maturation of immune regulation is largely driven by exposure to microbes. Germ free animals manifest excessive immune responses when immunised and they do not develop normal immune regulatory function. The gut is by far the largest source of microbial exposure, as the human gut microbiome contains up to 1014 bacteria, i.e. ten times the number of cells in the human body. Several studies in recent years have shown differences in the composition of the gut microbiota between allergic and non-allergic individuals and between infants living in countries with a low and a high prevalence of immune mediated diseases. The administration of probiotic bacteria to pregnant mothers and postnatal to their infants has immune modulatory effects. So far, however, probiotic bacteria do not seem to significantly enhance immune responses to vaccines. The potential to improve vaccine responses by modifying the gut microbiota in infants and the possibility to employ probiotic bacteria as adjuvants and/or delivery vehicles, is currently explored in several laboratories. Although to date few clinical results have been reported, experimental studies have shown some encouraging results.