Meta-analysis of clinical trials of probiotics for prevention and treatment of pediatric atopic dermatitis

The use of prebiotics during the first year of life for atopy prevention and treatment

The incidence of allergic diseases has increased in recent decades. Therefore, the aim of this systematic review was to assess the efficacy of prebiotics for the prevention and treatment of allergic manifestations in children. We sought to conduct a systematic review of the effectiveness of prebiotics in the prevention and treatment of allergic diseases in children. We searched the MEDLINE, EMBASE, Cochrane Library, LILACS, SciELO, IBECS, Web of Science and Clinical Trials databases as well as Google Scholar and the references of the articles identified. Randomised clinical trials, in which one of the treatments was performed with prebiotics and the control group was treated with placebo, were included in the review. The data selection were performed by two reviewers, and the study quality was evaluated according to the Consolidated Standards of Reporting Trials (CONSORT) items, according to the recommendations for improving the quality of reports of randomised clinical trials. The selected studies showed heterogeneity with regard to the participants, albeit with similar outcomes. The treatment group size ranged from 134 to 259 children, and the studies compared prebiotic to placebo treatment in each group. In general, these articles showed a trend toward less allergic reactions in the groups receiving active therapy with prebiotics. Although there was a trend for reduced allergic symptoms following the administration of prebiotics, there was not sufficient evidence to establish that such treatment is effective for the prevention of allergies in children.

Clinical efficacy and mechanism of probiotics in allergic diseases

A complex interplay between genetic and environmental factors partially contributes to the development of allergic diseases by affecting development during prenatal and early life. To explain the dramatic increase in the prevalence of allergic diseases, the hygiene hypothesis proposed that early exposure to infection prevented allergic diseases. The hygiene hypothesis has changed to the microbial hypothesis, in which exposure to microbes is closely linked to the development of the early immune system and allergic diseases. The intestinal flora may contribute to allergic disease through its substantial effect on mucosal immunity. Based on findings that exposure to microbial flora early in life can change the Th1/Th2 balance, thus favoring a Th1 cell response, probiotics may be beneficial in preventing allergic diseases. However, evidence from clinical and basic research to prove the efficacy of probiotics in preventing allergy is lacking. To date, studies have yielded inconsistent findings on the usefulness of probiotics in allergic diseases. It is difficult to demonstrate an exact effect of probiotics on asthma, allergic rhinitis, and food allergy because of study limitations, such as different first supplementation period, duration, different strains, short follow-up period, and host factors. However, many studies have demonstrated a significant clinical improvement in atopic dermatitis with the use of probiotics. An accurate understanding of the development of human immunity, intestinal barrier function, intestinal microbiota, and systemic immunity is required to comprehend the effects of probiotics on allergic diseases.

Probiotic effects in allergic disease

The increasing prevalence of allergic disease has been linked to reduced microbial exposure in early life. Probiotics have recently been advocated for the prevention and treatment of allergic disease. This article summarises recent publications on probiotics in allergic disease, focusing on clinical studies of prevention or treatment of allergic disease. Studies employing the combined administration of pre-natal and post-natal probiotics suggest a role for certain probiotics (alone or with prebiotics) in the prevention of eczema in early childhood, with the pre-natal component of treatment appearing to be important for beneficial effects. On the other hand, current data are insufficient to support the use of probiotics for the treatment of established allergic disease, although recent studies have highlighted new hope in this area. Probiotic bacteria continue to represent the most promising intervention for primary prevention of allergic disease, and well-designed definitive intervention studies should now be a research priority.

Probiotics and food allergy

The exact prevalence of food allergy in the general population is unknown, but almost 12% of pediatric population refers a suspicion of food allergy. IgE mediated reactions to food are actually the best-characterized types of allergy, and they might be particularly harmful especially in children. According to the "hygiene hypothesis" low or no exposure to exogenous antigens in early life may increase the risk of allergic diseases by both delaying the development of the immune tolerance and limiting the Th2/Th1 switch. The critical role of intestinal microbiota in the development of immune tolerance improved recently the interest on probiotics, prebiotics, antioxidants, polyunsaturated fatty acid, folate and vitamins, which seem to have positive effects on the immune functions.Probiotics consist in bacteria or yeast, able to re-colonize and restore microflora symbiosis in intestinal tract. One of the most important characteristics of probiotics is their safety for human health. Thanks to their ability to adhere to intestinal epithelial cells and to modulate and stabilize the composition of gut microflora, probiotics bacteria may play an important role in the regulation of intestinal and systemic immunity. They actually seem capable of restoring the intestinal microbic equilibrium and modulating the activation of immune cells.Several studies have been recently conducted on the role of probiotics in preventing and/or treating allergic disorders, but the results are often quite contradictory, probably because of the heterogeneity of strains, the duration of therapy and the doses administered to patients. Therefore, new studies are needed in order to clarify the functions and the utility of probiotics in food allergies and ion other types of allergic disorders.

Nonpathogenic bacteria alleviating atopic dermatitis inflammation induce IL-10-producing dendritic cells and regulatory Tr1 cells

The beneficial effects of nonpathogenic bacteria are increasingly being recognized. We reported in a placebo-controlled study with atopic dermatitis (AD) patients that cutaneous exposure to lysates of nonpathogenic bacteria alleviates skin inflammation. To now unravel underlying mechanisms, immune consequences of sensing nonpathogenic bacterium Vitreoscilla filiformis lysate (Vf) were characterized analyzing (1) differentiation of dendritic cells (DCs) and, consecutively, (2) effector functions of DCs and T helper (Th) cells in vitro and in a murine model of AD in NC/Nga mice in vivo. Topical treatment with Vf significantly reduced AD-like inflammation in NC/Nga mice. Importantly, cutaneous exposure to Vf in combination with the allergen FITC significantly also reduced subsequent allergen-induced dermatitis indicating active immune modulation. Indeed, innate sensing of Vf predominantly induced IL-10-producing DCs, which was dependent on Toll-like receptor 2 (TLR2) activation. Vf-induced IL-10+ DCs primed naive CD4+ T helper cells to become regulatory IFN-γ(low) IL-10(high) Tr1 (type 1 regulatory T) cells. These IL-10(high) Tr1 cells were also induced by Vf in vivo and strongly suppressed T effector cells and inflammation. In conclusion, we show that innate sensing of nonpathogenic bacteria by TLR2 induces tolerogenic DCs and regulatory Tr1 cells suppressing T effector cells and cutaneous inflammation. These findings indicate a promising therapeutic strategy for inflammatory skin diseases like AD.

Overview of atopic dermatitis

Atopic dermatitis (AD) is a very common chronic disease that reportedly affects 10%-20% of the general population. The prevalence of AD appears to be steadily increasing, at least in developing countries. Two pathogenetic mechanisms have been mentioned. Traditionally immunological aberrations are thought to be a primary event in the initial development of AD ("inside-to-outside hypothesis"). Another hypothesis assumes that there is an intrinsic defect in epidermal barrier. Due to this barrier defect, allergens or irritants can easily penetrate the epidermal barrier, and induce immunologic reaction secondarily ("outside-to-inside hypothesis"). These days the epidermal barrier defect seems to gain more support as a primary event than immunological aberrations in the early changes of AD since the filaggrin mutation was reported in AD patients. Clinically AD initially affects face, and with age, flexural areas are typically involved. AD has many different clinical features. Diagnostic criteria for AD in each country may be a little different, although based on the criteria proposed by Hanifin and Rajka. AD can be controlled effectively with topical and/or systemic treatments and fortunately spontaneously disappears with age. However, in some cases very resistant to conventional therapies, additional treatments such as immunosuppressive agents are needed.

New era of biologic therapeutics in atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is a common inflammatory skin disease regulated by genetic and environmental factors. Both skin barrier defects and aberrant immune responses are believed to drive cutaneous inflammation in AD. Existing therapies rely largely on allergen avoidance, emollients and topical and systemic immune-suppressants, some with significant toxicity and transient efficacy; no specific targeted therapies are in clinical use today. As our specific understanding of the immune and molecular pathways that cause different subsets of AD increases, a variety of experimental agents, particularly biologic agents that target pathogenic molecules bring the promise of safe and effective therapeutics for long-term use.

AREAS COVERED

This paper discusses the molecular pathways characterizing AD, the contributions of barrier and immune abnormalities to its pathogenesis, and development of new treatments that target key molecules in these pathways. In this review, we will discuss a variety of biologic therapies that are in development or in clinical trials for AD, perhaps revolutionizing treatment of this disease.

EXPERT OPINION

Biologic agents in moderate to severe AD offer promise for controlling a disease that currently lacks good and safe therapeutics posing a large unmet need. Unfortunately, existing treatments for AD aim to decrease cutaneous inflammation, but are not specific for the pathways driving this disease. An increasing understanding of the immune mechanisms underlying AD brings the promise of narrow targeted therapies as has occurred for psoriasis, another inflammatory skin disease, for which specific biologic agents have been demonstrated to both control the disease and prevent occurrence of new skin lesions. Although no biologic is yet approved for AD, these are exciting times for active therapeutic development in AD that might lead to revolutionary therapeutics for this disease.

Probiotics in the treatment and prevention of allergy in children

Several fold increase in allergic diseases in developed, high-income countries during recent decades is attributed to environmental changes such as urbanization with improved hygiene. This, together with conquering severe bacterial infections during childhood, has reduced the microbial stimulation of the developing immune system of infants. Studies on the pathogenesis of allergy both in man and experimental animal have shown the importance of commensal bacteria in the gastrointestinal tract in stimulating and directing the immune system. The interest in modulating commensal bacterial flora with probiotics to prevent and treat allergy has multiplied in recent years.

In the present review we report results on randomized, controlled studies in which childhood atopic eczema was treated or which aimed to prevent development of allergy during childhood.

Nine studies with 639 patients have looked at the effect of probiotics in treatment of eczema. While 3 studied showed no effect, other studies suggested a moderate benefit of the use of probiotics on the severity of eczema. Studies suggested that the effect may be seen particularly in patients with food allergy and/or sensitization.

Nine studies have reported on the prevention of allergy on 6 study population with altogether 1989 high risk infants. While the early study reporting the development of allergy at ages 2, 4 and 7 years showed a marked reduction of eczema in 77 treated infants, later studies have failed to show similar success. Two studies showed no effect. In the largest study with more than 900 children at age 2 atopic eczema was reduced by 20%, but at age 5 positive effect was present in only the subgroup of children who had born by cesarean section. None of studies has reported adverse effects of probiotics in infants.

Result in both treatment and prevention studies are quite variable, the major reason being the use of different strains of probiotic bacteria and varying types of intervention. Even if the results are encouraging, we need a stronger effect. This may be reached by finding new strains of probiotics affecting stronger stimulation of immune system, together with longer lasting and varying treatment schedules. However, safety issues have to be observed.

Characterization of candidate anti-allergic probiotic strains in a model of th2-skewed human peripheral blood mononuclear cells

BACKGROUND

Pre-clinical and clinical studies have evaluated the efficacy of probiotics in allergy. However, predictive in vitro systems for rational strain selection are still missing.

METHODS

We developed a novel in vitro screening system for the characterization of probiotics with anti-allergic potential. In this model, human peripheral blood mononuclear cells (PBMC) from healthy donors (n = 68) were skewed towards a Th2 cytokine phenotype by culture with IL-4 and anti-CD40, to resemble cells from allergic donors. Th2-skewed cells were then co-cultured with probiotics; a total of 35 strains were tested. Levels of IFN-γ, IL-10, IL-5 and 7 additional cytokines in culture supernatants were determined by ELISA or multiplex assay. Gene expression was assessed by real-time PCR. For validation, splenocytes from ovalbumin-primed mice and PBMC from grass-allergic donors were restimulated with respective antigen and co-cultured with probiotics, and cytokine profiles were correlated.

RESULTS

Culture with IL-4 and anti-CD40 antibody induced secretion of IL-5 from PBMC, indicative of induction of a Th2 phenotype. Cytokine profiles induced by probiotics were strain specific even though species- and genus-specific clustering was observed for many strains by principal component analysis. This was paralleled by mRNA levels of the corresponding genes such as increased Tbet and reduced GATA-3 gene expression. Cytokine profiles induced by probiotics in PBMC stimulated with IL-4 and anti-CD40 correlated with those obtained from allergen-stimulated murine splenocytes or human PBMC from grass-allergic donors.

CONCLUSIONS

Cytokine profiling of probiotic strains with IL-4-/anti-CD40-stimulated PBMC allowed to determine the effect of probiotics on Th2-skewed cells and thus to classify probiotic strains with anti-allergic potential.

Development of intestinal microbiota in infants and its impact on health

Throughout the human lifetime, the intestinal microbiota performs vital functions, such as barrier function, metabolic reactions, trophic effects, and maturation of the host's innate and adaptive immune responses. Development of the intestinal microbiota in infants is characterized by rapid and large changes in microbial abundance, diversity, and composition. These changes are influenced by medical, cultural, and environmental factors such as mode of delivery, diet, familial environment, diseases, and therapies used. Thus, it is nearly impossible to define a universal standard for intestinal colonization and development of the intestinal microbiota. This review discusses recent data on the early colonization of the gut by microbial species, development of the intestinal microbiota, and its impact on health.

Sources, isolation, characterisation and evaluation of probiotics

According to the FAO and the WHO, probiotics are 'live microorganisms which, when administered in adequate amounts, confer a health benefit on the host'. The strains most frequently used as probiotics include lactic acid bacteria and bifidobacteria, which are isolated from traditional fermented products and the gut, faeces and breast milk of human subjects. The identification of microorganisms is the first step in the selection of potential probiotics. The present techniques, including genetic fingerprinting, gene sequencing, oligonucleotide probes and specific primer selection, discriminate closely related bacteria with varying degrees of success. Additional molecular methods, such as denaturing gradient gel electrophoresis/temperature gradient gel electrophoresis and fluorescence in situ hybridisation, are employed to identify and characterise probiotics. The ability to examine fully sequenced genomes has accelerated the application of genetic approaches to the elucidation of the functional roles of probiotics. One of the best-demonstrated clinical benefits of probiotics is the prevention and treatment of acute and antibiotic-associated diarrhoea;however, there is mounting evidence for a potential role for probiotics in the treatment of allergies and intestinal, liver and metabolic diseases. There are various mechanisms by which probiotics exert their beneficial effects: regulation of intestinal permeability, normalisation of host intestinal microbiota, improvement of gut immune barrier function, and adjustment between pro- and anti-inflammatory cytokines. The number of studies carried out to test the effects of probiotics in vitro and in animals is enormous. However, the most reliable method of assessing the therapeutic benefits of any probiotic strain is the use of randomised, placebo-controlled trials, which are reviewed in this article [corrected].

Immune factors in breast milk and the development of atopic disease

Breast-feeding provides protection against infections and contains numerous factors that modulate and promote the development of the infant immune system. These factors include secretory IgA, antimicrobial proteins like CD14, cytokines, and fatty acids. Studies examining the role of breast-feeding in the development of allergic disease in infants demonstrate potentially protective as well as neutral or nonprotective effects, likely due to the heterogeneity in their study design. In this overview, we explore the potential role of immune factors in the breast milk, as well as selected probiotics, in the development of allergy.

Adaptation of bifidobacteria to the gastrointestinal tract and functional consequences

Members of the genus Bifidobacterium are considered to be important constituents of the microbiota of animals, from insects to mammals. They are gut commensals extensively used by the food industry as probiotic microorganisms, since some strains have been shown to have specific beneficial effects. However, the molecular processes underlying their functional capacities to promote a healthy status in the host, as well as those involved in survival, colonization and persistence of bifidobacteria in the gut, are far from being completely understood. This review summarizes the current knowledge on the mechanisms used by bifidobacteria to cope with gastrointestinal factors and to adapt to them, and discusses the advantages of the adaptive traits acquired by these microorganisms as a consequence of their interactions with the gastrointestinal tract environment, as well as the impact of such adaptations in the functional characteristics of bifidobacteria.

Clinical Use of Probiotics in Pediatric Allergy (CUPPA): A World Allergy Organization Position Paper

BACKGROUND

: Probiotic administration has been proposed for the prevention and treatment of specific allergic manifestations such as eczema, rhinitis, gastrointestinal allergy, food allergy, and asthma. However, published statements and scientific opinions disagree about the clinical usefulness.

OBJECTIVE

: A World Allergy Organization Special Committee on Food Allergy and Nutrition review of the evidence regarding the use of probiotics for the prevention and treatment of allergy.

METHODS

: A qualitative and narrative review of the literature on probiotic treatment of allergic disease was carried out to address the diversity and variable quality of relevant studies. This variability precluded systematization, and an expert panel group discussion method was used to evaluate the literature. In the absence of systematic reviews of treatment, meta-analyses of prevention studies were used to provide data in support of probiotic applications.

RESULTS

: Despite the plethora of literature, probiotic research is still in its infancy. There is a need for basic microbiology research on the resident human microbiota. Mechanistic studies from biology, immunology, and genetics are needed before we can claim to harness the potential of immune modulatory effects of microbiota. Meanwhile, clinicians must take a step back and try to link disease state with alterations of the microbiota through well-controlled long-term studies to identify clinical indications.

CONCLUSIONS

: Probiotics do not have an established role in the prevention or treatment of allergy. No single probiotic supplement or class of supplements has been demonstrated to efficiently influence the course of any allergic manifestation or long-term disease or to be sufficient to do so. Further epidemiologic, immunologic, microbiologic, genetic, and clinical studies are necessary to determine whether probiotic supplements will be useful in preventing allergy. Until then, supplementation with probiotics remains empirical in allergy medicine. In the future, basic research should focus on homoeostatic studies, and clinical research should focus on preventive medicine applications, not only in allergy. Collaborations between allergo-immunologists and microbiologists in basic research and a multidisciplinary approach in clinical research are likely to be the most fruitful.

Probiotic therapy as a novel approach for allergic disease

The prevalence of allergic disease has increased dramatically in Western countries over the past few decades. The hygiene hypothesis, whereby reduced exposure to microbial stimuli in early life programs the immune system toward a Th2-type allergic response, is suggested to be a major mechanism to explain this phenomenon in developed populations. Such microbial exposures are recognized to be critical regulators of intestinal microbiota development. Furthermore, intestinal microbiota has an important role in signaling to the developing mucosal immune system. Intestinal dysbiosis has been shown to precede the onset of clinical allergy, possibly through altered immune regulation. Existing treatments for allergic diseases such as eczema, asthma, and food allergy are limited and so the focus has been to identify alternative treatment or preventive strategies. Over the past 10 years, a number of clinical studies have investigated the potential of probiotic bacteria to ameliorate the pathological features of allergic disease. This novel approach has stemmed from numerous data reporting the pleiotropic effects of probiotics that include immunomodulation, restoration of intestinal dysbiosis as well as maintaining epithelial barrier integrity. In this mini-review, the emerging role of probiotics in the prevention and/or treatment of allergic disease are discussed with a focus on the evidence from animal and human studies.

Probiotic supplement use among young children in Taiwan: a prospective cohort study

OBJECTIVES

The objective of this study is to provide details on probiotic supplement use among young children in Taiwan.

PARTICIPANTS AND METHODS

This study is based on the Taiwan Birth Cohort Study database. We used questionnaires to collect information on probiotic supplement use among young children from birth to 18 months of age, while also considering their demographic characteristics and other covariates. Low-birth-weight infants, preterm infants, those with birth defects, and those with caregivers who returned incomplete questionnaires were excluded. The final valid sample comprised 16,991 cases.

RESULTS

Approximately half the children received probiotic supplements before the age of 18 months. Only 6.3% of the children received probiotic supplements during the two periods of birth to 6 months and 7 to 18 months. Firstborn children, native mothers, mothers with higher educational levels, higher family income, and parents who lead healthy lifestyles were positively related to probiotic supplement use among children. Young children who were breastfed, with eczema, or with gastrointestinal tract problems were significantly positively associated with probiotic supplement use.

CONCLUSION

The findings show that probiotic supplement usage among young children is associated with a more socially advantaged circumstance and certain child health factors, such as eczema, diarrhea, and constipation. Parents might use probiotic supplements for prevention or treatment of child diseases. The findings of this research could serve as a baseline for future studies, and provide insight into probiotic supplement use behavior for health professionals caring for infants and young children.

Probiotics and atopic dermatitis in children

There is increasing interest in the potential beneficial role of probiotic supplementation in the prevention and treatment of atopic diseases in children. Probiotics are defined as ingested live microorganisms that, when administered in an adequate amount, confer a health benefit to the host. They are mainly represented by Lactobacilli and Bifidobacteria. Several epidemiological data demonstrate that intestinal microflora of atopic children is different from the one of healthy children. Many literature data show that probiotics may modulate the intestinal microflora composition and may have immunomodulatory effect. Based on this hypothesis, probiotics are supposed to confer benefits to allergic diseases. Administration of probiotics when a natural population of indigenous intestinal bacteria is still developing could theoretically influence immune development by favoring the balance between Th1 and Th2 inflammatory responses. For this reason, some studies have evaluated the potential impact of probiotics supplementation in the prevention of atopic dermatitis, with contrasting results. Clinical improvement in immunoglobulin (Ig)E-sensitized (atopic) eczema following probiotic supplementation has been reported in some published studies and the therapeutic effects of probiotics on atopic dermatitis seemed to be encouraging. However, as far as the usefulness of probiotics as a prevention strategy is concerned, results are still inconclusive. In fact, the clinical benefits of probiotic therapy depend upon numerous factors, such as the type of bacteria, dosing regimen, delivery method and other underlying host factors, such as age and diet. More studies are still needed to definitively prove the role of probiotics in the treatment of allergic eczema.

Microbial ecology and host-microbiota interactions during early life stages

The role of human microbiota has been redefined during recent years and its physiological role is now much more important than earlier understood. Intestinal microbial colonization is essential for the maturation of immune system and for the developmental regulation of the intestinal physiology. Alterations in this process of colonization have been shown to predispose and increase the risk to disease later in life. The first contact of neonates with microbes is provided by the maternal microbiota. Moreover, mode of delivery, type of infant feeding and other perinatal factors can influence the establishment of the infant microbiota. Taken into consideration all the available information it could be concluded that the exposure to the adequate microbes early in gestation and neonatal period seems to have a relevant role in health. Maternal microbial environment affects maternal and fetal immune physiology and, of relevance, this interaction with microbes at the fetal-maternal interface could be modulated by specific microbes administered to the pregnant mother. Indeed, probiotic interventions aiming to reduce the risk of immune-mediated diseases may appear effective during early life.

Fetal origins of asthma

There is convincing evidence that asthma has its origins in early life. We review the epidemiological and biological evidence for fetal exposures that may have a causal role in asthma development. However, those factors that provoke asthma exacerbations are not necessarily the same as those associated with disease induction. Epidemiological studies have identified many potential exposures linked to asthma but these do not confirm causality and have not been replicated by experiment. Asthma is a heterogeneous disease and there are developmental influences on at least two pathways, airway structure and airway inflammation. The fetus is not immunologically naive and intrauterine exposures can act directly to invoke immunological sensitisation leading postnatally to airway inflammation. Other potential mechanisms include indirect effects on airway and lung growth through fetal nutrition and epigenetic modifications of DNA expression by environmental exposures. Identifying the causal factors will provide the targets for interventions to prevent disease.

In vitro assessment of the immunomodulatory effects of multispecies probiotic formulations for management of allergic diseases

Modulation of the composition of the intestinal microbiota with probiotics could possibly offer a way of prevention or management of allergic diseases. The objective of this study was to determine the immunomodulating effects of various multispecies probiotic combinations in vitro, as preamble to application in vivo. Multispecies probiotic combinations were formulated and tested for their effects on in vitro cytokine production by human mononuclear cells and were compared to products that already have shown beneficial effects in vivo. All 4 tested combinations of probiotics showed a 40-71% decrease of Th2 cytokine production (IL-4, IL-5, and IL-13) and a variable increase of Th1 (IFN-γ) and Treg cytokine (IL-10) production compared to the medium. A specific probiotic mixture that contained Bifidobacterium breve W25, Bifidobacterium lactis ATCC SD 5219, B. lactis ATCC SD 5220, Lactobacillus plantarum W62, Lactobacillus salivarius W57 and Lactococcus lactis W19 was superior in its stimulating effect on IL-10 production (significant better than the other tested combinations; P=0.001). Modulation of in vitro cytokine production profiles can be used to differentiate between selected probiotic formulations for their immunomodulatory properties. In the future it should be demonstrated whether the immunomodulatory capacities from the multispecies probiotic formulation with the desired profile will be effective in vivo (in adolescents, followed by application in children).

Food formats for effective delivery of probiotics

Probiotic bacteria are increasingly incorporated into food products intended to confer health benefits in the human gut and beyond. Little is known about how the food matrix and product formulation impacts probiotic functionality, even though such information is essential to scientific understanding and regulatory substantiation of health benefits. The food format has the potential to affect probiotic survival, physiology, and potentially efficacy, but few comparative studies in humans have been conducted. Human studies should account for the effects of the food base on human health and the bioactive components present in the foods that may augment or diminish interactions of the probiotic with the human host. Some studies show that food ingredients such as prebiotics and milk components can improve probiotic survival during the shelf life of foods, which may enhance probiotic efficacy through increased dose effects. Furthermore, there are indications that synbiotic products are more effective than either probiotics or prebiotics alone. Identification of probiotic adaptations to the food and gut environments holds promise for determining the specific cell components and potential bacterial-food interactions necessary for health benefits and determining how these factors are affected by changes in food formulation and host diet. These studies, combined with controlled human studies, are important future research activities for advancing this field.

Probiotics in the management of children with allergy and other disorders of intestinal inflammation

Soon after birth, the human gastrointestinal tract quickly becomes colonised by a variety of bacterial species. Throughout life the gastrointestinal tract continues to serve as host to a complex society of nonpathological bacteria. Microorganisms, such as probiotics, have the potential to modulate mucosal immune response and reduce gastrointestinal inflammation caused by a variety of infectious and allergic events. The most widely studied genera of probiotics are lactobacilli and bifidobacteria. Lactobacillus rhamnosis strain ATC53103 (LGG) can replenish gut flora during infectious diarrhoeal episodes. This beneficial effect is carried over to traveller's diarrhoea and children experiencing antibiotic-associated diarrhoea. Furthermore, LGG can reduce the risk of respiratory tract infections in children attending daycares and hospitals. With allergic disease on the rise, probiotics have the potential to positively impact atopic dermatitis, asthma, and allergic rhinitis. LGG has been shown to decrease the severity and delay the onset of atopic dermatitis. Additionally, LGG is beneficial in the treatment of allergic colitis and necrotising entercolitis. Some strains of probiotics appear to be useful in the treatment and/or prevention of allergic disease, however, caution must be used when generalising the effectiveness of a specific strain of organism to other organisms and other disease states.

Intestinal microbiota and health in childhood

Western medicine has only recently discovered that the intestinal microbiota is a major determinant of the well-being of the host. Although it would be oversimplifying to limit the benefits of breastfeeding compared to cow milk based infant formula to differences in gastrointestinal flora, the impact of the latter has been demonstrated beyond doubt. As a consequence, gastro intestinal flora manipulation with pre- and probiotics added to infant formula or food (mainly milk based products) and/or with food supplements have become a priority area of high quality research. The composition of intestinal microbiota can be manipulated with “biotics”: antibiotics, prebiotics and probiotics. Commercialised pre- and probiotic products differ in composition and dose. Major threats to the concept of developing a major role for intestinal microbiota manipulation on health are the commercialisation of products claiming health benefits that have not been validated. Legislation of food supplements and medication differs substantially and allows commercialisation of poor quality food supplements, what will result in negative experiences. Medicinal products can only be advertised for which there is scientific proof of benefit that has been demonstrated with “the same product with the same dose in the same indication”. Specificity of prebiotics and probiotics strains and product specificity are of importance, although high quality evidence for this assertion is missing. Dose-efficacy studies are urgently needed. Probiotics are “generally regarded as safe”, but side effects such as septicemia and fungemia have sometimes been reported in high-risk situations.

Intestinal defensin secretion in infancy is associated with the emergence of sensitization and atopic dermatitis

BACKGROUND

Intestinal flora and innate immunity, and their interactions impact adaptive immunity.

OBJECTIVE

To study the association of fecal defensin levels in infancy with synbiotic treatment and with the emergence of atopy.

METHODS

The randomly selected group of 102 infants belonged to a randomized, double-blind placebo-controlled trial where 1223 infants in high risk for allergy received, from birth to 6 months, a mixture of synbiotics, or placebo. Clinical trials registration number for the clinical trial is NCT00298337. In the subgroup, 45 received active treatment and 56 received placebo treatment. Follow-up for the emergence of sensitization and allergic diseases lasted 5 years. At the age of 3 (n = 96) and 6 (n = 87) months, we measured fecal levels of human neutrophil peptide (HNP) 1-3 and of β-defensin 2 (HBD2) using enzyme linked immunosorbent assays and concentrations of lactic acid bacteria on MRS agar. We used multifactorial regression in data analysis.

RESULTS

Fecal levels of HNP1-3 and HBD2 decreased from the age of 3-6 months (P < 0.0001). HBD2 levels decreased less in the synbiotics group compared with placebo (P < 0.02). High fecal HBD2 levels at 6 months were associated with an increased risk for sensitization by the age of 5 years (OR 2.5, 95% confidence interval 1.1-5.8, P < 0.03). High fecal HNP1-3 levels at 6 months were associated with a decreased risk for atopic dermatitis (OR 0.4, 95% CI 0.1-1.0, P < 0.05). Samples with very low or high HBD2 levels at 6 months had low concentrations of lactic acid bacteria (P < 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

Early innate immunity responses in the gut are associated with the emergence of sensitization and atopic dermatitis later in childhood.

The relationship of rhinitis and asthma, sinusitis, food allergy, and eczema

Epidemiologic, genetic, immunologic, and clinical studies show a close relationship between allergic rhinitis and asthma, food allergy, and atopic dermatitis. Rhinitis and sinusitis often coexist and are commonly referred to with the term rhinosinusitis. These conditions are also linked in the so-called atopic march, which is the sequential appearance of atopic manifestations starting with atopic dermatitis and later followed by food allergy, allergic rhinitis, and asthma. Allergic rhinitis and asthma are now increasingly being approached diagnostically and therapeutically as the one-airway concept.

Effect of heat-inactivated kefir-isolated Lactobacillus kefiranofaciens M1 on preventing an allergic airway response in mice

In this study, we assessed the anti-asthmatic effects of heat-inactivated Lactobacillus kefiranofaciens M1 (HI-M1) and its fermented milk using different feeding procedures and at various dosage levels. The possible mechanisms whereby HI-M1 has anti-allergic asthmatic effects were also evaluated. Ovalbumin (OVA)-allergic asthma mice that have been orally administrated the HI-M1 samples showed strong inhibition of production of T helper cell (Th) 2 cytokines, pro-inflammatory cytokines, and Th17 cytokines in splenocytes and bronchoalveolar fluid compared to control mice. An increase in regulatory T cell population in splenocytes in the allergic asthma mice after oral administration of H1-M1 was also observed. In addition, all of the features of the asthmatic phenotype, including specific IgE production, airway inflammation, and development of airway hyperresponsiveness, were depressed in a dose-dependent manner by treatment. These findings support the possibility that oral feeding of H1-M1 may be an effective way of alleviating asthmatic symptoms in humans.

Ovalbumin-specific immunoglobulins A and G levels at age 2 years are associated with the occurrence of atopic disorders

BACKGROUND

Humoral responses to food antigens may reflect the propensity of a child's immune system to develop tolerance to innocuous antigens. Early nutrition as well as probiotics may influence these immunological responses.

OBJECTIVE

To study the association of humoral responses to early food antigens with the administration of prebiotics and probiotics, with the occurrence of allergy, and with the length of exclusive breastfeeding.

METHODS

In a randomized double-blind allergy prevention trial in high-risk children, 1018 mothers took probiotics or placebo from the 36th week of gestation, and their newborn infants received probiotics and prebiotics or placebo during 6 months. At 2 and 5 years, we evaluated the cumulative incidence of allergic diseases (food allergy, eczema, asthma, rhinitis) and sensitization (skin prick test ≥3 mm or serum antigen-specific IgE>0.7 kU/L). In 688 infants at age 2, we measured in sera-specific IgA, IgG, IgG1, and IgG4 antibody levels to cow's milk (CM), α-casein (CAS), β-lactoglobulin (BLG), and ovalbumin (OVA) with ELISA, and specific IgE levels to CM and hen's egg with UniCap.

RESULTS

Probiotic treatment (n=342) compared with placebo (n=346) showed no effect on serum food-specific IgA, IgG, IgG1, or IgG4 concentrations at age 2. Atopic children had higher OVA-IgA (P<0.001), OVA-IgG (P=0.001), OVA-IgG1 (P<0.001), and egg-IgE but lower OVA-IgG4/egg-IgE ratio (P<0.001) than non-atopic children. Longer duration of exclusive breastfeeding (≥4 vs. <4 months) was associated with reduced CM- and CAS-specific serum IgA (P<0.001) and IgG levels (P<0.001; P=0.003).

CONCLUSION AND CLINICAL RELEVANCE

Allergy was associated with more intense IgA and IgG responses to OVA. Breastfeeding depressed humoral responses, whereas prebiotics and probiotics supplementation showed no immunomodulatory effect. The effect of probiotics on allergies is not mediated through food-specific antibody responses. Furthermore, OVA-specific IgA and IgG antibodies may help in assessing the risk for atopy.

Oral administration of Escherichia coli Nissle 1917 prevents allergen-induced dermatitis in mice

BACKGROUND

The prevalence of allergies has been linked to Western life style factors including a decrease of microbial exposure. Probiotics, such as Escherichia coli Nissle 1917 (EcN), have been shown to be beneficial for prevention and treatment of several chronic inflammatory diseases.

OBJECTIVE

The aim of this study was to investigate the impact of oral EcN administration on development and outcome of allergen-induced dermatitis.

METHODS

In sensitized BALB/c mice, skin inflammation was induced by topical allergen application. EcN was administered orally in a preventive manner. Severity of dermatitis was analysed by evaluation of skin score, local cellular and cytokine profile. The systemic immune response was assessed by analysis of immunoglobulins and allergen-dependent cytokine response.

RESULTS

Oral EcN administration improved allergen-induced dermatitis dose-dependently. In parallel, a reduction of epidermal thickness and infiltrating immune cells together with an enhanced number of forkhead box P3 (Foxp3)(+) cells and a trend of increased IFNγ, IL-10 and TGFβ expression was detected in eczematous skin. In allergen-stimulated splenocytes reduced IL-4 and IFNγ along with an elevated IL-10 production and a tendency to an increased TGFβ secretion were observed.

CONCLUSIONS

Our findings indicate that EcN alters the local allergen-induced immune response by increase of Foxp3(+) cells and by favouring an immunoregulatory cytokine pattern. Thus, oral administration of EcN might be an effective strategy in prevention and potentially therapy of allergic inflammatory skin diseases.

Strategies of mucosal immunotherapy for allergic diseases

Incidences of allergic disease have recently increased worldwide. Allergen-specific immunotherapy (SIT) has long been a controversial treatment for allergic diseases. Although beneficial effects on clinically relevant outcomes have been demonstrated in clinical trials by subcutaneous immunotherapy (SCIT), there remains a risk of severe and sometimes fatal anaphylaxis. Mucosal immunotherapy is one advantageous choice because of its non-injection routes of administration and lower side-effect profile. This study reviews recent progress in mucosal immunotherapy for allergic diseases. Administration routes, antigen quality and quantity, and adjuvants used are major considerations in this field. Also, direct uses of unique probiotics, or specific cytokines, have been discussed. Furthermore, some researchers have reported new therapeutic ideas that combine two or more strategies. The most important strategy for development of mucosal therapies for allergic diseases is the improvement of antigen formulation, which includes continuous searching for efficient adjuvants, collecting more information about dominant T-cell epitopes of allergens, and having the proper combination of each. In clinics, when compared to other mucosal routes, sublingual immunotherapy (SLIT) is a preferred choice for therapeutic administration, although local and systemic side effects have been reported. Additionally, not every allergen has the same beneficial effect. Further studies are needed to determine the benefits of mucosal immunotherapy for different allergic diseases after comparison of the different administration routes in children and adults. Data collected from large, well-designed, double-blind, placebo-controlled, and randomized trials, with post-treatment follow-up, can provide robust substantiation of current evidence.

Maternal signals for progeny prevention against allergy and asthma

Allergy and asthma are chronic inflammatory diseases which result from complex gene-environment interactions. Recent evidence indicates the importance of prenatal and postnatal developmental processes in terms of maturation of balanced immune responses. According to the current view, gene-environment interactions during a restricted time frame are responsible for programming of the immune system in favor of allergic immune mechanisms later in life. The interaction between genes and environment is complex and only partially understood; however, heritable epigenetic modifications including chemical additions in and alternative packaging of the DNA have been shown to play a crucial role in this context. Novel data indicate that epigenetic mechanisms contribute to the development of T-helper cell function. Environmental factors, including diesel exhaust particles (DEP), vitamins and tobacco smoke, operate through such mechanisms. Furthermore, the role of environmental microbes provides another and maybe even more important group of exogenous exposures which operates in this critical time frame.

The role of microbes in developmental immunologic programming

The role of microorganisms in the gastrointestinal tract has undergone significant modification in the past few decades with new observations from clinical, epidemiologic, and basic science research. We now know that the perception of these gut microbes as pathogens or even as commensals is somewhat outdated. It is becoming increasingly clear that the gut microbiome plays an important role in a host of activities including digestion, protection from potentially pathogenic organisms, and the regulation and development of the host immune system. The complex interactions between microbes and host combined with recent clinical observations and epidemiologic trends may point to the convergence of two well-supported (though imperfect) hypotheses: the "hygiene hypothesis" and the "fetal programming hypothesis." We are beginning to understand that exposure to microbes before conception, during gestation, and in the neonatal period have profound effects on the developing immune system. Recent observations from a variety of fields help support the expansion of the "fetal programming hypothesis" to a host-microbe corollary that microbe-host interactions at critical windows influence the future immune phenotype, the maintenance of immune health, and the development of immune-mediated disease.

Can food allergy be prevented? The current evidence

Food allergy is a recognized public health concern, for which preventative strategies are required. Although an intervention that adequately protects against the development of food allergy has still to be identified, limited benefits have been shown for the prevention of related allergic conditions such as eczema, and to a lesser extent asthma and rhinitis; these benefits are usually limited to at-risk populations. Prevention strategies need to be tested using randomized controlled study designs that account for the numerous methodological challenges, safety concerns, and necessary ethical limitations.

Oral therapeutic administration of a probiotic mixture suppresses established Th2 responses and systemic anaphylaxis in a murine model of food allergy

BACKGROUND

No effective treatment is available for food allergy and its primary management still consists of avoiding relevant allergens. Probiotics are claimed to beneficially affect the immune system. We sought to investigate the therapeutic potential of VSL#3 probiotic mixture on specific immune responses and anaphylactic reaction induced in mice by the major food allergen shrimp tropomyosin (ST).

METHODS

The cytokine production by spleen cell from ST-sensitized mice upon allergen re-stimulation in the presence of VSL#3 was analysed. Next, the effects of oral administration of VSL#3 on allergen-induced anaphylaxis and Th2 response in the murine model of food allergy to ST was investigated by evaluating symptom score and histamine content in the faeces after allergen challenge, antibody response in serum and faeces, and cytokine and transcription factor expression in the jejunum.

RESULTS

The in vitro studies on mouse spleen cells indicates that the VSL#3 preparation has the capacity to shift a polarized Th2 response to a Th1/T regulatory-type profile. Oral therapeutic administration of VSL#3 to ST-sensitized mice significantly reduces symptom score and histamine release in the faeces following allergen challenge, as well as specific IgE response. In the jejunum, IL-4, IL-5 and IL-13 tissue content was significantly reduced, whereas FOXP3 and IL-27 mRNA expression, IL-10, TGF-β and IFN-γ tissue content were up-regulated.

CONCLUSIONS

Oral therapeutic treatment with the probiotic mixture VSL#3 is effective in redirecting allergen-specific Th2-polarized immune responses towards Th1-T regulatory responses and in the protection against anaphylactic reactions induced by the allergen in a murine model of food allergy.

Integrative care of the mother-infant dyad

There are many options for natural and preventative therapies during pregnancy and childbirth, which may aid in minimizing the use of pharmaceuticals and invasive procedures. Patients may seek these out, and it is important for physicians to have some basic knowledge to guide their choices. Of all therapies, the most important are nutrition for optimizing health and the provision of continuous support during labor.

Fetal epigenetic mechanisms and innate immunity in asthma

Allergy and asthma are chronic inflammatory diseases that result from complex gene-environment interactions. Recent evidence points to the importance of prenatal and postnatal developmental processes in the maturation of balanced immune responses. Novel data indicate that epigenetic mechanisms contribute to the development of T-helper-cell function. Environmental factors, including diesel exhaust particles, vitamins, and tobacco smoke, operate through such mechanisms. Furthermore, the role of environmental microbes provides another-and maybe an even more important-group of exogenous exposures that operate in this critical time frame. A better understanding of fetal immuno-maturation conditions will provide the basis for the development of novel allergo-protective clinical strategies.

Probiotics and prebiotics: clinical effects in allergic disease

PURPOSE OF REVIEW

This paper summarizes recent publications on probiotics and prebiotics in allergic disease. It focuses on clinical studies of prevention or treatment of allergic disease.

RECENT FINDINGS

Studies suggest a role for certain probiotics (alone or with prebiotics) in the prevention of atopic eczema. Treatment during the prenatal period appears to be important for beneficial effects. The use of probiotics for the treatment of established allergic disease is less promising, despite some positive results. A Cochrane systematic review concluded that, when the results for the different probiotic strains used in clinical trials are pooled, probiotics are not effective for the treatment of eczema. There are fewer studies of prebiotics for the treatment or prevention of allergic disease, but data suggest that prebiotic-supplemented formulas may be effective for preventing eczema in infants at high risk of developing allergic disease when breast-feeding is not possible.

SUMMARY

Allergic diseases continue to increase in prevalence worldwide, and primary prevention of allergic disease has proved an elusive goal. Probiotic bacteria represent the most promising intervention for primary prevention that has been studied to date, and definitive intervention studies should now be a research priority.