Oral application of bacterial lysate in infancy decreases the risk of atopic dermatitis in children with 1 atopic parent in a randomized, placebo-controlled trial

Advances in Bacterial Lysate Immunotherapy for Infectious Diseases and Cancer

Antigenic cell fragments, pathogen-associated molecular patterns, and other immunostimulants in bacterial lysates or extracts may induce local and systemic immune responses in specific and nonspecific paradigms. Based on current knowledge, this review aimed to determine whether bacterial lysate has comparable functions in infectious diseases and cancer treatment. In infectious diseases, including respiratory and urinary tract infections, immune system activation by bacterial lysate can identify and combat pathogens. Commercially available bacterial lysates, including OM-85, Ismigen, Lantigen B, and LW 50020, were effective in children and adults in treating respiratory tract infections, chronic obstructive pulmonary disease, rhinitis, and rhinosinusitis with varying degrees of success. Moreover, OM-89, Uromune, Urovac, Urivac, and ExPEC4V showed therapeutic benefits in controlling urinary tract infections in adults, especially women. Bacterial lysate-based therapeutics are safe, well-tolerated, and have few side effects, making them a good alternative for infectious disease management. Furthermore, a nonspecific immunomodulation by bacterial lysates may stimulate innate immunity, benefiting cancer treatment. "Coley's vaccine" has been used to treat sarcomas, carcinomas, lymphomas, melanomas, and myelomas with varying outcomes. Later, several similar bacterial lysate-based therapeutics have been developed to treat cancers, including bladder cancer, non-small cell lung cancer, and myeloma; among them, BCG for in situ bladder cancer is well-known. Proinflammatory cytokines, including IL-1, IL-6, IL-12, and TNF-α, may activate bacterial antigen-specific adaptive responses that could restore tumor antigen recognition and response by tumor-specific type 1 helper cells and cytotoxic T cells; therefore, bacterial lysates are worth investigating as a vaccination adjuvants or add-on therapies for several cancers.

Extracellular Matrix Remodeling in Atopic Dermatitis Harnesses the Onset of an Asthmatic Phenotype and Is a Potential Contributor to the Atopic March

The development of atopic dermatitis in infancy, and subsequent allergies, such as asthma in later childhood, is known as the atopic march. The mechanism is largely unknown, however the course of disease indicates an inter-epithelial crosstalk, through the onset of inflammation in the skin and progression to other mucosal epithelia. In this study, we investigated if and how skin-lung epithelial crosstalk contributes to the development of the atopic march. First, we emulated inter-epithelial crosstalk through indirect coculture of bioengineered atopic-like skin disease models and three-dimensional bronchial epithelial models triggering an asthma-like phenotype in the latter. A subsequent secretome analysis identified thrombospondin-1, CD44, complement factor C3, fibronectin, and syndecan-4 as potentially relevant skin-derived mediators. Because these mediators are extracellular matrix-related proteins, we then studied the involvement of the extracellular matrix, unveiling distinct proteomic, transcriptomic, and ultrastructural differences in atopic samples. The latter indicated extracellular matrix remodeling triggering the release of the above-mentioned mediators. In vivo mouse data showed that exposure to these mediators dysregulated activated circadian clock genes which are increasingly discussed in the context of atopic diseases and asthma development. Our data point toward the existence of a skin-lung axis that could contribute to the atopic march driven by skin extracellular matrix remodeling.

Probiotics supplementation during pregnancy or infancy on multiple food allergies and gut microbiota: a systematic review and meta-analysis

CONTEXT

Probiotics show promise in preventing and managing food allergies, but the impact of supplementation during pregnancy or infancy on children's allergies and gut microbiota remains unclear.

OBJECTIVE

This study aimed to assess the effects of maternal or infant probiotic supplementation on food allergy risk and explore the role of gut microbiota.

DATA SOURCES

A systematic search of databases (PubMed, Cochrane Library, Embase, and Medline) identified 37 relevant studies until May 20, 2023.

DATA EXTRACTION

Two independent reviewers extracted data, including probiotics intervention details, gut microbiota analysis, and food allergy information.

DATA ANALYSIS

Probiotics supplementation during pregnancy and infancy reduced the risk of total food allergy (relative risk [RR], 0.79; 95% CI, 0.63-0.99), cow-milk allergy (RR, 0.51; 95% CI, 0.29-0.88), and egg allergy (RR, 0.57; 95% CI, 0.39-0.84). Infancy-only supplementation lowered cow-milk allergy risk (RR, 0.69; 95% CI, 0.49-0.96), while pregnancy-only had no discernible effect. Benefits were observed with over 2 probiotic species, and a daily increase of 1.8 × 109 colony-forming units during pregnancy and infancy correlated with a 4% reduction in food allergy risk. Children with food allergies had distinct gut microbiota profiles, evolving with age.

CONCLUSIONS

Probiotics supplementation during pregnancy and infancy reduces food allergy risk and correlates with age-related changes in gut microbial composition in children.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023425988.

From the Friend to the Foe-Enterococcus faecalis Diverse Impact on the Human Immune System

Enterococcus faecalis is a bacterium which accompanies us from the first days of our life. As a commensal it produces vitamins, metabolizes nutrients, and maintains intestinal pH. All of that happens in exchange for a niche to inhabit. It is not surprising then, that the bacterium was and is used as an element of many probiotics and its positive impact on the human immune system and the body in general is hard to ignore. This bacterium has also a dark side though. The plasticity and relative ease with which one acquires virulence traits, and the ability to hide from or even deceive and use the immune system to spread throughout the body make E. faecalis a more and more dangerous opponent. The statistics clearly show its increasing role, especially in the case of nosocomial infections. Here we present the summarization of current knowledge about E. faecalis, especially in the context of its relations with the human immune system.

Evolving Advances in the Cosmetic use of Probiotics and Postbiotics: Health, Regulatory and Marketing Aspects

Ongoing development in cosmetics is increasingly making use of probiotics, which are defined as "live microorganisms with health-enhancing properties mediated through ingestion or topical application to the host". The observation that several bacterial strains augment normal processes of healthy tissue maintenance, particularly for the skin, has opened up new avenues for the use of bacterial strains in cosmetics. A principal feature of such "cosmeceuticals" is an application of increasing insight into the biochemical nature of the skin's normal microbial flora, also called its microbiome. The opportunity of manipulating the skin microbiome to address various skin disorders has revealed novel routes for treatment. The skin microbiome manipulation approaches to address various skin disorders include skin microbiome transplantation, skin bacteriotherapy, and prebiotic stimulation. Research in this field has revealed that medical outcome-targeted manipulation of skin microbiome bacterial strain makeup may significantly increase skin health and appearance. Commercial availability of probiotic skincare products is rapidly expanding worldwide due to satisfactory laboratory results and public perception of probiotics as being intrinsically more wholesome than other bioactive substances, such as synthetics. Major outcomes of probiotic use include a significant reduction in skin wrinkling, acne and other conditions adversely affecting skin appearance and healthy function. Moreover, probiotics may additionally promote normal skin hydration, resulting in a vibrant and lustrous appearance. Nevertheless, significant technical challenges remain for the full optimization of probiotics in cosmetic products. This article summarizes the evolving nature of this field and explores current probiotic research initiatives, along with regulatory aspects and significant challenges in the manufacturing of cosmetics in the context of market expansion for these products.

Impact of local human microbiota on the allergic diseases: Organ-organ interaction

The homogeneous impact of local dysbiosis on the development of allergic diseases in the same organ has been thoroughly studied. However, much less is known about the heterogeneous influence of dysbiosis within one organ on allergic diseases in other organs. A comprehensive analysis of the current scientific literature revealed that most of the relevant publications focus on only three organs: gut, airways, and skin. Moreover, the interactions appear to be mainly unidirectional, that is, dysbiotic conditions of the gut being associated with allergic diseases of the airways and the skin. Similar to homogeneous interactions, early life appears to be not only a crucial period for the formation of the microbiota in one organ but also for the later development of allergic diseases in other organs. In particular, we were able to identify a number of specific bacterial and fungal species/genera in the intestine that were repeatedly associated in the literature with either increased or decreased allergic diseases of the skin, like atopic dermatitis, or the airways, like allergic rhinitis and asthma. The reported studies indicate that in addition to the composition of the microbiome, also the relative abundance of certain microbial species and the overall diversity are associated with allergic diseases of the corresponding organs. As anticipated for human association studies, the underlying mechanisms of the organ-organ crosstalk could not be clearly resolved yet. Thus, further work, in particular experimental animal studies are required to elucidate the mechanisms linking dysbiotic conditions of one organ to allergic diseases in other organs.

Current Use of Probiotics and Prebiotics in Allergy

The microbiome plays an important role in the pathogenesis of allergic diseases. This review updates the reader on studies aimed at influencing allergic diseases through modulation of the gut microflora. A nonsystematic review of the literature was performed, focusing on relevant trials evaluating the effect of probiotics/prebiotics/symbiotics in the prevention and treatment of allergic disease. For each allergic disease, we were able to find not only a substantial number of clinical trials but also systematic reviews. Specific guidelines, based on systematic reviews and meta-analyses, are available for the prevention of allergic disease and for the treatment of food allergy. In each of the areas examined-allergic rhinitis, allergic asthma, atopic dermatitis, food allergy, and gastrointestinal allergies-there are substantial uncertainties in the efficacy of gut microflora modulation in prevention and treatment. At present, practicing clinicians can avail themselves of intestinal flora modulators as an adjunct in the prevention of atopic dermatitis but not of other forms of allergic diseases. Their effects on the treatment of allergic diseases remain controversial.

Perspectives for the Use of Bacterial Lysates for the Treatment of Allergic Rhinitis: A Systematic Review

Bacterial lysates (BLs) are mixtures of bacterial antigens that have been used for many decades to minimize the risk of recurrent respiratory tract infections in both pediatric and adult populations. Research on the use of BLs is also conducted in allergology. Biomedical databases were searched for articles on the use of BLs in the treatment of allergic rhinitis (AR). After rejecting ineligible articles, six remaining reports were reviewed. Based on this review, it can be concluded that adding BL to standard therapy for seasonal or perennial AR reduces the severity of nasal symptoms and the need for antiallergic medications in both children and adults. Concurrently, these formulations have a high safety profile. An analysis of studies shows that the first effects of BLs therapy appear at the earliest 2–6 weeks after the start of treatment and persist at least 3 months after treatment.

Nasal carriage of Staphylococcus aureus in children with grass pollen‐induced allergic rhinitis and the effect of polyvalent mechanical bacterial lysate immunostimulation on carriage status: A randomized controlled trial

Background

Numerous studies indicate that Staphylococcus aureus (S. aureus) colonizing the nasal cavity plays a role in the pathogenesis of allergic rhinitis (AR). This bacterium is able to produce a variety of toxins with superantigenic properties that can exacerbate allergic inflammation.

Objective

The objective of the study was to evaluate the ability of polyvalent mechanical bacterial lysate (PMBL) to eliminate S. aureus nasal carriage in children with grass pollen‐induced AR.

Methods

This randomized, double‐blind, placebo‐controlled study included 80 children aged 5–17 years with seasonal AR (SAR). At the randomization visit and after 12 weeks of the study, a swab was taken from the region of the middle nasal meatus. Standard microbiology culture and identification techniques were used to analyze the swab contents.

Results

Nasal colonization by S. aureus was confirmed in 29 children (42%), with Moraxella catarrhalis in three participants (4.4%). Physiological flora was detected in 37 children. No statistically significant differences were observed between the two measurement points in both the PMBL and placebo groups with respect to the number of patients whose nasal swab cultures showed a growth of S. aureus (p = 1). Both groups also showed no significant changes in the mean number of S. aureus colonies in nasal swab cultures taken at baseline and after 12 weeks of the study (PMBL group p = .41; placebo group p = .16).

Conclusion

Almost every second child with SAR is S. aureus nasal carrier. Sublingual administration of PMBL in children with grass pollen‐induced AR did not affect S. aureus nasal colonization. Therefore, PMBL should not be used for the eradication of S. aureus from the nasal cavity.

Recent advances in the concept of paraprobiotics: Nutraceutical/functional properties for promoting children health

Probiotics consumption has been associated with various health promoting benefits, including disease prevention and even treatment by modulating gut microbiota. Contrary to this, probiotics may also overstimulate the immune system, trigger systemic infections, harmful metabolic activities, and promote gene transfer. In children, the fragile immune system and impaired intestinal barrier may boost the occurrence of adverse effects following probiotics' consumption. To overcome these health challenges, the key focus has been shifted toward non-viable probiotics, also called paraprobiotics. Cell wall polysaccharides, peptidoglycans, surface proteins and teichoic acid present on cell's surface are involved in the interaction of paraprobiotics with the host, ultimately providing health benefits. Among other benefits, paraprobiotics possess the ability to regulate innate and adaptive immunity, exert anti-adhesion, anti-biofilm, anti-hypertensive, anti-inflammatory, antioxidant, anti-proliferative, and antagonistic effects against pathogens, while also enhance clinical impact and general safety when administered in children in comparison to probiotics. Clinical evidence have underlined the paraprobiotics impact in children and young infants against atopic dermatitis, respiratory and gastrointestinal infections, in addition to be useful for immunocompromised individuals. Therefore, this review focuses on probiotics-related issues in children's health and also discusses the Lactobacillus and Bifidobacterium spp. qualities for qualifying as paraprobiotics and their role in promoting the children's health.

Dangerous liaisons: Bacteria, antimicrobial therapies, and allergic diseases

Microbiota composition and associated metabolic activities are essential for the education and development of a healthy immune system. Microbial dysbiosis, caused by risk factors such as diet, birth mode, or early infant antimicrobial therapy, is associated with the inception of allergic diseases. In turn, allergic diseases increase the risk for irrational use of antimicrobial therapy. Microbial therapies, such as probiotics, have been studied in the prevention and treatment of allergic diseases, but evidence remains limited due to studies with high heterogeneity, strain-dependent effectiveness, and variable outcome measures. In this review, we sketch the relation of microbiota with allergic diseases, the overuse and rationale for the use of antimicrobial agents in allergic diseases, and current knowledge concerning the use of bacterial products in allergic diseases. We urgently recommend 1) limiting antibiotic therapy in pregnancy and early childhood as a method contributing to the reduction of the allergy epidemic in children and 2) restricting antibiotic therapy in exacerbations and chronic treatment of allergic diseases, mainly concerning asthma and atopic dermatitis. Future research should be aimed at antibiotic stewardship implementation strategies and biomarker-guided therapy, discerning those patients that might benefit from antibiotic therapy.

Bacterial lysate treatment in allergic disease: A systematic review and meta-analysis

OBJECTIVE

The aim of this review was to assess the efficacy of bacterial lysate treatment in patients with allergic disease.

METHOD

Randomized controlled trials (RCTs) of bacterial lysate therapy for patients with allergic diseases (asthma, atopic dermatitis, and allergic rhinitis) were searched using PubMed, EMBASE, Cochrane, China National Knowledge Infrastructure, Chinese Biomedical literature, and Wanfang databases up to March 2020. Based on the guidelines of the Cochrane collaboration, risk of bias was assessed.

RESULTS

This meta-analysis based on 19 studies comparing bacterial lysate-treated patients with a control group showed a 24% (RR: 1.24, 95% CI [1.19, 1.30]) increase in improvement of allergy symptom control. In addition, the improvement of asthma symptom control was 22% (RR: 1.22, 95% CI [1.14, 1.26]) higher in the bacterial lysate treatment group. Moreover, the levels of immunoglobulin (IgA and IgG), T lymphocyte subtype (CD3+, CD4+, CD4+/CD8+, Th1), and cytokines (IFN-γ, IL-2, and IL-12) were increased in the treated group compared with controls. There was no significant difference in adverse event rate between the two groups.

CONCLUSION

Treatment with bacterial lysate improves symptom control in patients with allergic diseases on the basis of routine therapy. No adverse risk was found in this meta-analysis.

Microbiome Modulation as a Therapeutic Approach in Chronic Skin Diseases

There is a growing quantity of evidence on how skin and gut microbiome composition impacts the course of various dermatological diseases. The strategies involving the modulation of bacterial composition are increasingly in the focus of research attention. The aim of the present review was to analyze the literature available in PubMed (MEDLINE) and EMBASE databases on the topic of microbiome modulation in skin diseases. The effects and possible mechanisms of action of probiotics, prebiotics and synbiotics in dermatological conditions including atopic dermatitis (AD), psoriasis, chronic ulcers, seborrheic dermatitis, burns and acne were analyzed. Due to the very limited number of studies available regarding the topic of microbiome modulation in all skin diseases except for AD, the authors decided to also include case reports and original studies concerning oral administration and topical application of the pro-, pre- and synbiotics in the final analysis. The evaluated studies mostly reported significant health benefits to the patients or show promising results in animal or ex vivo studies. However, due to a limited amount of research and unambiguous results, the topic of microbiome modulation as a therapeutic approach in skin diseases still warrants further investigation.

Comparative effectiveness of probiotic strains on the prevention of pediatric atopic dermatitis: A systematic review and network meta-analysis

BACKGROUND

Atopic dermatitis is the most common chronic skin disease affecting the pediatric population. Probiotics have been proposed to be effective in preventing the development of pediatric atopic dermatitis. Although studies show promise for the use of probiotics, the evidence is still inconclusive due to significant heterogeneity and imprecision.

OBJECTIVE

To determine the comparative effectiveness of the different types of probiotic strains in preventing the development of atopic dermatitis among pediatric patients.

METHODOLOGY

A systematic search of Cochrane Library, MEDLINE, TRIP Database, and Centre for Research and Dissemination was conducted. Manual search of the reference lists and search for unpublished articles were also done. All randomized controlled trials available from inception until April 12, 2020, on the use of probiotics in the prevention of atopic dermatitis among children were included. The comparator groups considered are other probiotic strains and placebo. The primary outcome of interest was the development of atopic dermatitis. Two authors independently searched for articles, screened the articles for inclusion, appraised the articles using the Cochrane risk of bias tool version 2, and extracted the data. In case of disagreement, the two authors discussed the source of disagreement until consensus was reached. If consensus was not reached, an independent third party reviewer was consulted. Frequentist network meta-analysis was conducted using STATA 14 software. The ranking probabilities and surface under the cumulative ranking curve (SUCRA) values were obtained to determine ranking of the different probiotic strains based on efficacy and safety data.

RESULTS

We included 21 original studies represented by 35 records and a total of 5406 children with atopic dermatitis as diagnosed by clinicians or fulfillment of validated diagnostic criteria. All studies were randomized placebo-controlled trials. The top 3 probiotic preparations in terms of efficacy in reducing the risk of atopic dermatitis are Mix8 (Lactobacillus paracasei ST11, Bifidobacterium longum BL999), LP (Lactobacillus paracasei ssp paracasei F19) and Mix3 (Lactobacillus rhamnosus GG, Bifidobacterium animalis ssp lactis Bb-12). Mix8 compared with placebo probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.46, 95% CI 0.25-0.85). Mix3 compared with placebo also probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.50, 95% CI 0.27-0.94). It is uncertain whether LP compared with placebo reduces the risk of atopic dermatitis due to very-low-quality certainty of evidence (RR = 0.49, 95% CI 0.20-1.19). In terms of adverse events, LGG may slightly lead to less adverse events compared with placebo based on low-quality evidence (RR = 0.70, 95% CI 0.32-1.52). Mix4 may slightly lead to more adverse events compared with placebo based on low-quality evidence (RR = 1.06, 95% CI 0.02-51.88). Based on subgroup analysis of studies involving infants, Mix3 compared with placebo probably reduces the risk of atopic dermatitis based on low-quality evidence (RR = 0.46, 95% CI 0.22-0.97). In the subgroup analysis of studies where probiotics were administered to pregnant women and to infants, LRH compared with placebo probably reduces the risk of atopic dermatitis based on moderate-quality evidence (RR = 0.54, 95% CI 0.26-1.11).

CONCLUSION

Certain probiotic preparations demonstrate efficacy in reducing the risk of developing atopic dermatitis when administered to pregnant women, infants, or both.

Precision medicine reaching out to the patients in allergology - a German-Japanese workshop report

An expert workshop in collaboration of the German Society of Allergy and Clinical Immunology (DGAKI) and the Japanese Society of Allergy (JSA) provided a platform for key opinion leaders of both countries aimed to join expertise and to highlight current developments and achievements in allergy research. Key domains of the meeting included the following seven main sections and related subchapters: 1) basic immunology, 2) bronchial asthma, 3) prevention of allergic diseases, 4) food allergy and anaphylaxis, 5) atopic dermatitis, 6) venom allergy, and 7) upper airway diseases. This report provides a summary of panel discussions of all seven domains and highlights unmet needs and project possibilities of enhanced collaborations of scientific projects.

Probiotics as a Possible Strategy for the Prevention and Treatment of Allergies. A Narrative Review

Allergies are an increasing global public health concern, especially for children and people living in urban environments. Allergies impair the quality of life of those who suffer from them, and for this reason, alternatives for the treatment of allergic diseases or reduction in their symptoms are being sought. The main objective of this study was to compile the studies carried out on probiotics as a possible therapy for allergies. The most studied allergies on which probiotics have been shown to have a beneficial effect are rhinitis, asthma, and atopic dermatitis. Most studies have studied the administration of Lactobacillus and Bifidobacterium spp. in children and have shown beneficial effects, such as a reduction in hyperreactivity and inflammation caused by allergens and a decrease in cytokine release, among other beneficial effects. In the case of children, no clear beneficial effects were found in several studies, and the potential risk from the use of some opportunistic bacteria, such as probiotics, seems controversial. In the studies that reported beneficial results, these effects were found to make allergy symptoms less aggressive, thus reducing morbidity in allergy sufferers. The different effects of the same probiotic bacteria on different patients seem to reinforce the idea that the efficacy of probiotics is dependent on the microbial species or strain, its derived metabolites and byproducts, and the gut microbiota eubiosis of the patient. This study is relevant in the context of allergic diseases, as it provides a broader understanding of new alternatives for the treatment of allergies, both in children, who are the main sufferers, and adults, showing that probiotics, in some cases, reduce the symptoms and severity of such diseases.

Impact of Polyvalent Mechanical Bacterial Lysate on lymphocyte number and activity in asthmatic children: a randomized controlled trial

BACKGROUND

Polyvalent Mechanical Bacterial Lysate (PMBL®) contains antigens of bacteria responsible for respiratory infections. PMBL® has been proven to reduce the number of respiratory infections, and in its use, immunological benefits have been seen in allergic patients. PMBL® activates both innate and specific immune responses. The lysate induces dendritic cells, T and B lymphocytes and IgA secretion, as well as the production of antibodies directed against administered bacterial antigens. Moreover, it increases the response against other bacteria and viruses. The immunologic mechanism of lysate's action is not yet clearly determined. The objective of this study was to assess the effect of PMBL® on T cells in children with allergic asthma.

METHODS

This study was a part of the EOLIA study. Herein, 49 children with allergic asthma and house dust mites allergy were included: 21 in PMBL® and 28 in the Placebo group, both, drug and placebo were administered sublingually. The tests were done at baseline and 12 weeks after the last tablet intake. The lymphocytes CD45+, lymphocytes T CD3+, CD3+CD25+, CD3+CD69+, Th CD3+CD4+, CD4+CD25+, CD4+CD25+ high, CD4+CD69+, Treg CD4+CD25+FOXP3, Tc CD3+CD8+, CD8+CD25+, CD8+CD69+, NK-like T CD3+CD16+CD56+ and NK cells CD3-CD16+CD56+ were described.

RESULTS

At baseline, no significant differences between groups relative to blood count cells were observed, except for eosinophils. After 12 weeks, we observed an increase of T lymphocytes count. In addition, CD4+CD25+FOXP3+, CD8+ and CD3-CD16+CD56+ and (insignificantly) Th count increased. However, CD69+ and CD25+ subset of CD3+ significantly decreased.

CONCLUSIONS

The EOLIA study demonstrated that PMBL® administration 10 days per month for 3 months changed the panel of T lymphocytes. Trial registration Clinical Trial Registration: This study was a part of the EOLIA (Efficacy Of mechanical bacterial Lysate In Allergic children), a clinical study NCT02541331. Frederic Durmont, MD Lallemand Pharma International AG. Date of registration 09/08/2013. URL of trial registry record: https://clinicaltrials.gov/ct2/show/study/NCT02541331.

The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics

In 2019, the International Scientific Association for Probiotics and Prebiotics (ISAPP) convened a panel of experts specializing in nutrition, microbial physiology, gastroenterology, paediatrics, food science and microbiology to review the definition and scope of postbiotics. The term 'postbiotics' is increasingly found in the scientific literature and on commercial products, yet is inconsistently used and lacks a clear definition. The purpose of this panel was to consider the scientific, commercial and regulatory parameters encompassing this emerging term, propose a useful definition and thereby establish a foundation for future developments. The panel defined a postbiotic as a "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host". Effective postbiotics must contain inactivated microbial cells or cell components, with or without metabolites, that contribute to observed health benefits. The panel also discussed existing evidence of health-promoting effects of postbiotics, potential mechanisms of action, levels of evidence required to meet the stated definition, safety and implications for stakeholders. The panel determined that a definition of postbiotics is useful so that scientists, clinical triallists, industry, regulators and consumers have common ground for future activity in this area. A generally accepted definition will hopefully lead to regulatory clarity and promote innovation and the development of new postbiotic products.

Mechanisms Underlying the Skin-Gut Cross Talk in the Development of IgE-Mediated Food Allergy

Immune-globulin E (IgE)-mediated food allergy is characterized by a variety of clinical entities within the gastrointestinal tract, skin and lungs, and systemically as anaphylaxis. The default response to food antigens, which is antigen specific immune tolerance, requires exposure to the antigen and is already initiated during pregnancy. After birth, tolerance is mostly acquired in the gut after oral ingestion of dietary proteins, whilst exposure to these same proteins via the skin, especially when it is inflamed and has a disrupted barrier, can lead to allergic sensitization. The crosstalk between the skin and the gut, which is involved in the induction of food allergy, is still incompletely understood. In this review, we will focus on mechanisms underlying allergic sensitization (to food antigens) via the skin, leading to gastrointestinal inflammation, and the development of IgE-mediated food allergy. Better understanding of these processes will eventually help to develop new preventive and therapeutic strategies in children.

Polyvalent Mechanical Bacterial Lysate Administration Improves the Clinical Course of Grass Pollen-Induced Allergic Rhinitis in Children: A Randomized Controlled Trial

BACKGROUND

Recent studies highlight the immunoregulatory potential of bacterial lysates, indicating their potential use in the prevention and treatment of allergic diseases.

OBJECTIVE

To investigate the clinical efficacy of polyvalent mechanical bacterial lysates (PMBLs) in children with grass pollen-induced allergic rhinitis.

METHODS

Seventy children with seasonal allergic rhinitis were enrolled to this study and were randomly assigned to the PMBL and placebo groups. Severity of seasonal allergic rhinitis symptoms was assessed by the total nasal symptom score, total ocular symptom score, and visual analogue scale. During 3 visits, peak nasal inspiratory flow was measured, and nasal smears for the presence of eosinophils and nasal lavage fluids for the presence of allergen-specific IgE against timothy grass pollen allergens were sampled.

RESULTS

A statistically significant decrease in total nasal symptom score (P = .001), total ocular symptom score (P = .04), and visual analogue scale score for nasal and eye symptoms (P < .001 and P < .001, respectively) and an increase in peak nasal inspiratory flow (P = .04) were observed in the PMBL group versus the placebo group. During the grass pollen season, an increase and then a decrease in the number of eosinophils in nasal smears was observed in both groups; however, the number of eosinophils was significantly lower in the PMBL group versus the placebo group. No significant changes in allergen-specific IgE concentrations were observed in the PMBL group, whereas in the placebo group a statistically significant increase in allergen-specific IgE concentration was observed.

CONCLUSIONS

Sublingual administration of PMBLs during the grass pollen season offers significant efficacy in alleviating seasonal allergic rhinitis symptoms in children sensitized to grass pollen allergens. PMBLs probably affect mucosal immunity, weakening the response of T_H2 cells.

A decreased abundance of clostridia characterizes the gut microbiota in eosinophilic esophagitis

Abnormalities in the gut microbiome are associated with suppressed Th2 response (Belizario et al., 2018 Mediators Inflamm. 2018:2037838) and predisposition to atopic disease such as asthma and eczema. We investigated if this applies to eosinophilic esophagitis (EoE). Stool bacterial DNA was extracted and followed by 16S rRNA amplification from 12 patients with eosinophilic esophagitis and 12 controls. Alpha‐ and beta‐diversity were analyzed. Only two patients had asthma or atopy and one patient was on budesonide. No patients were on PPIs. Patients with EoE had lower gut microbiota alpha diversity (species richness, P = 0.09; Shannon index, P = 0.01). The microbial composition was distinct as evidenced by significantly different beta diversity (P = 0.03) when compared to healthy controls. There were also significant differences in relative abundance at multiple taxonomic levels when comparing the two communities; at the phylum level, we observed a marked decrease in Firmicutes and increase in Bacteroidetes and at the order and family level there were significant decreases in Clostridia and Clostridiales in patients with EoE (q ≤ 0.1). We conclude that there are significant differences in microbial community structure, microbial richness, and evenness and a significant decrease in taxa within the Clostridia in patients with EoE. Our data suggest that Clostridia based interventions could be tested as adjuncts to current therapeutic strategies in EoE.

Orally applied bacterial lysate in infants at risk for atopy does not prevent atopic dermatitis, allergic rhinitis, asthma or allergic sensitization at school age: Follow-up of a randomized trial

BACKGROUND

The allergy preventive effects of gut immune modulation by bacterial compounds are still not fully understood.

OBJECTIVE

We sought to evaluate the effect of bacterial lysate applied orally from the second until seventh months of life on the prevalence of allergic diseases at school age.

METHODS

In a randomized, placebo-controlled trial, 606 newborns with at least one allergic parent received orally a bacterial lysate consisting of heat-killed Gram-negative Escherichia coli Symbio and Gram-positive Enterococcus faecalis Symbio or placebo from week 5 until the end of month 7. A total of 402 children were followed until school age (6-11 years) for the assessment of current atopic dermatitis (AD), allergic rhinitis (AR), asthma and sensitization against aeroallergens.

RESULTS

AD was diagnosed in 11.0% (22/200) of children in the active and in 10.4% (21/202) of children in the placebo group. AR was diagnosed in 35% (70/200) of children in the active and in 38.1% (77/202) children in the placebo group. Asthma was diagnosed in 9% (18/199) of children in the active and in 6.6% (13/197) of children in the placebo group. Sensitization occurred in 46.5% (66/142) of participants in the active and 51.7% (76/147) in the placebo group.

CONCLUSION

An oral bacterial lysate of heat-killed Gram-negative Escherichia coli and Gram-positive Enterococcus faecalis applied during the first 7 months of life did not influence the development of AD, asthma and AR at school age.

Postbiotics and paraprobiotics: A review of current evidence and emerging trends

In recent years, new probiotic-related concepts such as postbiotics and paraprobiotics have been coined to indicate that non-viable microorganisms or bacterial-free extracts may provide benefits to the host by offering additional bioactivities to probiotics, including but not limited to anti-inflammatory, immunomodulatory, anti-proliferative and antioxidant activities. Despite in vitro and in vivo studies that support the promising use of postbiotics and paraprobiotics as health promoters, the mechanism of action and the signaling pathway involved have not yet been fully elucidated. Therefore, the aim of this chapter is to provide an overview of novel probiotic-related concepts and the scientific evidence that supports their bioactivities as well as the possible mechanisms underlying their health-promoting effects. Additionally, current trends in food, feed, and pharmaceutical applications are discussed.

Postbiotics and paraprobiotics: From concepts to applications

In recent years, new probiotic-related concepts such as postbiotics and paraprobiotics have been used to describe non-viable microorganisms or bacterial-free extracts that may provide benefits to the host by offering bioactivities additional to probiotics. However, several aspects related to these postbiotics and paraprobiotics bioactivities remain unexplored or are poorly understood. Therefore, the aim of this work is to provide an overview of the general aspects and emerging trends of postbiotics and paraprobiotics, such as conceptualization of terms, production, characterization, bioactivities, health-promoting effects, bioengineering approaches, and applications. In vitro and in vivo studies have demonstrated that some postbiotics and paraprobiotics exhibit bioactivities such as anti-inflammatory, immunomodulatory, anti-proliferative, antioxidant, and antimicrobial. These bioactivities could be involved in health-promoting effects observed in human and clinical trials, but despite the scientific evidence available, the mechanisms of action and the signaling pathways involved have not been fully elucidated. Nevertheless, paraprobiotics and postbiotics possess valuable potential for the development of biotechnological products with functional ingredients for the nutraceutical industry.

Development of the Microbiota and Associations With Birth Mode, Diet, and Atopic Disorders in a Longitudinal Analysis of Stool Samples, Collected From Infancy Through Early Childhood

BACKGROUND & AIMS

Establishment of the gastrointestinal microbiota during infancy affects immune system development and oral tolerance induction. Perturbations in the microbiome during this period can contribute to development of immune-mediated diseases. We monitored microbiota maturation and associations with subsequent development of allergies in infants and children.

METHODS

We collected 1453 stool samples, at 5, 13, 21, and 31 weeks postpartum (infants), and once at school age (6-11 years), from 440 children (49.3% girls, 24.8% born by cesarean delivery; all children except for 6 were breastfed for varying durations; median 40 weeks; interquartile range, 30-53 weeks). Microbiota were analyzed by amplicon sequencing. Children were followed through 3 years of age for development of atopic dermatitis; data on allergic sensitization and asthma were collected when children were school age.

RESULTS

Diversity of fecal microbiota, assessed by Shannon index, did not differ significantly among children from 5 through 13 weeks after birth, but thereafter gradually increased to 21 and 31 weeks. Most bacteria within the Bacteroidetes and Proteobacteria phyla were already present at 5 weeks after birth, whereas many bacteria of the Firmicutes phylum were acquired at later times in infancy. At school age, many new Actinobacteria, Firmicutes, and Bacteroidetes bacterial taxa emerged. The largest increase in microbial diversity occurred after 31 weeks. Vaginal, compared with cesarean delivery, was most strongly associated with an enrichment of Bacteroides species at 5 weeks through 31 weeks. From 13 weeks onward, diet became the most important determinant of microbiota composition; cessation of breastfeeding, rather than solid food introduction, was associated with changes. For example, Bifidobacteria, staphylococci, and streptococci significantly decreased on cessation of breastfeeding, whereas bacteria within the Lachnospiraceae family (Pseudobutyrivibrio, Lachnobacterium, Roseburia, and Blautia) increased. When we adjusted for confounding factors, we found fecal microbiota composition to be associated with development of atopic dermatitis, allergic sensitization, and asthma. Members of the Lachnospiraceae family, as well as the genera Faecalibacterium and Dialister, were associated with a reduced risk of atopy.

CONCLUSIONS

In a longitudinal study of fecal microbiota of children from 5 weeks through 6 to 11 years, we tracked changes in diversity and composition associated with the development of allergies and asthma.

Development of allergic airway inflammation in early life - interaction of early viral infections and allergic sensitization

Airway inflammation is a key feature of upper and lower respiratory allergic diseases, such as allergic rhinitis and asthma. Characteristically, histological alterations such as goblet cell hyperplasia, mucus hypersecretion, loss of epithelial barrier function, airway infiltration and structural changes such as basal membrane thickening and airway smooth muscle hyperplasia. These inflammatory signs are often obvious already early in life and may be accompanied by structural changes (remodeling) occurring in early lifetime. This review focusses on the main mechanisms underlying the development of airway inflammation and remodeling and discusses the question which factors contribute to the persistence of airway inflammation in chronic allergic airway disease.

Probiotics against airway allergy: host factors to consider

The worldwide prevalence of allergic diseases has drastically increased in the past decades. Recent studies underline the importance of microbial exposure for the development of a balanced immune system. Consequently, probiotic bacteria are emerging as a safe and natural strategy for allergy prevention and treatment. However, clinical probiotic intervention studies have so far yielded conflicting results. There is increasing awareness about the importance of host-associated factors that determine whether an individual will respond to a specific probiotic treatment, and it is therefore crucial to promote a knowledge-based instead of an empirical selection of promising probiotic strains and their administration regimen.In this Review, we summarize the insights from animal model studies of allergic disease, which reveal how host-related factors - such as genetic makeup, sex, age and microbiological status - can impact the outcomes of preventive or curative probiotic treatment. We explore why and how these factors can influence the results of probiotic studies and negatively impact the reproducibility in animal experiments. These same factors might profoundly influence the outcomes of human clinical trials, and can potentially explain the conflicting results from probiotic intervention studies. Therefore, we also link these host-related factors to human probiotic study outcomes in the context of airway allergies.

Changing perspectives in atopic dermatitis

Atopic dermatitis (AD) is a multifaceted disease that involves a complex interplay between the skin and the immune system. The course of the disease depends strongly on the genetic background of the patient and on yet poorly-defined environmental factors. Changes in lifestyle could be behind the dramatic rise in the prevalence of AD across continents; including hygienic conditions, food, social habits, skin microbiome or exposure to a number of allergens. Although AD typically develops in childhood and disappears after a few years, in a relatively large number of patients it continues into adulthood. Adult AD can also appear de novo but it is often underdiagnosed and its treatment can be challenging. New, highly effective drugs are being developed to manage moderate and severe forms of the disease in adults. In this review, we highlight the most recent developments in diagnostic tools, current insights into the mechanistic basis of this disease, and therapeutic innovations.

The potential of anti-infectives and immunomodulators as therapies for asthma and asthma exacerbations

Asthma is responsible for approximately 25,000 deaths annually in Europe despite available medicines that maintain asthma control and reduce asthma exacerbations. Better treatments are urgently needed for the control of chronic asthma and reduction in asthma exacerbations, the major cause of asthma mortality. Much research spanning >20 years shows a strong association between microorganisms including pathogens in asthma onset, severity and exacerbation, yet with the exception of antibiotics, few treatments are available that specifically target the offending pathogens. Recent insights into the microbiome suggest that modulating commensal organisms within the gut or lung may also be a possible way to treat/prevent asthma. The European Academy of Allergy & Clinical Immunology Task Force on Anti-infectives in Asthma was initiated to investigate the potential of anti-infectives and immunomodulators in asthma. This review provides a concise summary of the current literature and aimed to identify and address key questions that concern the use of anti-infectives and both microbe- and host-based immunomodulators and their feasibility for use in asthma.

Is there a role for modified probiotics as beneficial microbes: a systematic review of the literature

Our objective was to conduct a systematic review and meta-analysis for the use of modified (heat-killed or sonicated) probiotics for the efficacy and safety to prevent and treat various diseases. Recent clinical research has focused on living strains of probiotics, but use in high-risk patients and potential adverse reactions including bacteremia has focused interest on alternatives to the use of live probiotics. We searched MEDLINE/PubMed, Embase, Cochrane Central Register of Controlled Trials, CINAHL, Alt Health Watch, Web of Science, Scopus, PubMed, from inception to February 14, 2017 for randomised controlled trials involving modified probiotic strains. The primary outcome was efficacy to prevent or treat disease and the secondary outcome was incidence of adverse events. A total of 40 trials were included (n=3,913): 14 trials (15 arms with modified probiotics and 20 control arms) for the prevention of diseases and 26 trials (29 arms with modified probiotics and 32 control arms) for treatment of various diseases. Modified microbes were compared to either placebo (44%), or the same living probiotic strain (39%) or to only standard therapies (17%). Modified microbes were not significantly more or less effective than the living probiotic in 86% of the preventive trials and 69% of the treatment trials. Modified probiotic strains were significantly more effective in 15% of the treatment trials. Incidence rates of adverse events were similar for modified and living probiotics and other control groups, but many trials did not collect adequate safety data. Although several types of modified probiotics showed significant efficacy over living strains of probiotics, firm conclusions could not be reached due to the limited number of trials using the same type of modified microbe (strain, daily dose and duration) for a specific disease indication. Further research may illuminate other strains of modified probiotics that may have potential as clinical biotherapeutics.

Adjuvant treatment with the bacterial lysate (OM-85) improves management of atopic dermatitis: A randomized study

Background

Environmental factors play a major role on atopic dermatitis (AD) which shows a constant rise in prevalence in western countries over the last decades. The Hygiene Hypothesis suggesting an inverse relationship between incidence of infections and the increase in atopic diseases in these countries, is one of the working hypothesis proposed to explain this trend.

Objective

This study tested the efficacy and safety of oral administration of the bacterial lysate OM-85 (Broncho-Vaxom^®, Broncho-Munal^®, Ommunal^®, Paxoral^®, Vaxoral^®), in the treatment of established AD in children.

Methods

Children aged 6 months to 7 years, with confirmed AD diagnosis, were randomized in a double-blind, placebo-controlled trial to receive, in addition to conventional treatment with emollients and topical corticosteroids, 3.5mg of the bacterial extract OM-85 or placebo daily for 9 months. The primary end-point was the difference between groups in the occurrence of new flares (NF) during the study period, evaluated by Hazard Ratio (HR) derived from conditional Cox proportional hazard regression models accounting for repeated events.

Results

Among the 179 randomized children, 170 were analysed, 88 in the OM-85 and 82 in the placebo group. As expected most children in both treatment groups experienced at least 1 NF during the study period (75 (85%) patients in the OM-85 group and 72 (88%) in the placebo group). Patients treated with OM-85 as adjuvant therapy had significantly fewer and delayed NFs (HR of repeated flares = 0.80; 95% confidence interval (CI): 0.67–0.96), also when potential confounding factors, as family history of atopy and corticosteroids use, were taken into account (HR = 0.82; 95% CI: 0.69–0.98). No major side effect was reported, with comparable and good tolerability for OM-85 and placebo.

Conclusions

Results show an adjuvant therapeutic effect of a well standardized bacterial lysate OM-85 on established AD.

Diet Matters: Endotoxin in the Diet Impacts the Level of Allergic Sensitization in Germ-Free Mice

Germ-free animals have been used to define the vital role of commensal bacteria on the maturation of the host immune system. However, the role of bacterial residues in diet in this setting is poorly understood. Here we investigated the effect of bacterial contamination in sterile diet on the level of allergic sensitization in germ-free mice. Sterile grain-based diets ST1 and R03 were tested for the level of bacterial contamination. ST1 contained higher amount of bacterial DNA, approximately ten times more endotoxin, and induced higher, TLR4-dependent, cytokine production in dendritic cells compared to R03. In a germ-free mouse model of sensitization to the major birch pollen allergen Bet v 1, feeding on ST1 for at least two generations was associated with decreased production of allergen-specific IgE and IgG1 antibodies in sera in comparison to R03. Furthermore, reduced levels of allergen-specific and ConA-induced cytokines IL-4, IL-5 and IL-13 accompanied by increased levels of IFN-γ were detected in splenocytes cultures of these mice. Our results show that contamination of experimental diet with bacterial residues, such as endotoxin, significantly affects the development of allergic sensitization in germ-free mice. Therefore, careful selection of sterile food is critical for the outcomes of germ-free or gnotobiotic experimental models of immune-deviated diseases.

Elevated blood eosinophils in early infancy are predictive of atopic dermatitis in children with risk for atopy

BACKGROUND

Accessible markers to predict the development of atopic diseases are highly desirable but yet matter of debate.

OBJECTIVE

We investigated the role of blood eosinophils at 4 weeks and 7 months of life and their association with developing atopic dermatitis (AD) in a birth cohort of children with atopic heredity.

METHODS

Infant blood samples for eosinophil counts were taken from 559 infants at 4 weeks and from 467 infants at 7 month of life with at least one atopic parent. Elevation of blood eosinophils was defined as ≥ 5% of total leukocytes and the asscociation for the occurrence of AD was assessed by entering 2 × 2 tables and the odds ratios were estimated followed by hypothesis testing against the alternate working hypothesis: odds ratio < > 1. Survival analysis was carried out estimating the Kaplan-Meier product limit estimator from the life-time table of AD score and time to AD manifestation stratified by the eosinophil binary score.

RESULTS

Elevated blood eosinophils observed at 4 weeks were significantly associated with the occurrence of AD in the whole cohort at the age of 7 months (p = 0.007), 1 year (p = 0.004), 2 years (p = 0.007) and 3 years (p = 0.006) of life. AD occurred app. 12 weeks earlier in infants with elevated blood eosinophils at 4 weeks of life. Blood eosinophil counts ≥5% at 7 months of life failed to show significance for AD; for eosinophils at 4.5% a significant association at 7 months (p = 0.005), and 1 year of life (p = 0.039), 2 years (p = 0.033) and 3 years (p = 0.034) was observed.

CONCLUSION

Elevated blood eosinophils at age 4 weeks have a predictive value for the onset of atopic dermatitis in infancy and early childhood in children with high risk for atopy. Early eosinophil counts may therefore be helpful for counseling parents to provide infant skincare but furthermore identify individuals for interventional trials aiming at allergy prevention.

Microbes and asthma: Opportunities for intervention

The worldwide incidence and prevalence of asthma continues to increase. Asthma is now understood as an umbrella term for different phenotypes or endotypes, which arise through different pathophysiologic pathways. Understanding the many factors contributing to development of the disease is important for the identification of novel therapeutic targets for the treatment of certain asthma phenotypes. The hygiene hypothesis has been formulated to explain the increasing prevalence of allergic disease, including asthma. This hypothesis postulates that decreased exposure at a young age to certain infectious agents as a result of improved hygiene, increased antibiotic use and vaccination, and changes in lifestyle and dietary habits is associated with changes in the immune system, which predispose subjects to allergy. Many microbes, during their coevolution with human subjects, developed mechanisms to manipulate the human immune system and to increase their chances of survival. Improving models of asthma, as well as choosing adequate end points in clinical trials, will lead to a more complete understanding of the underlying mechanisms, thus providing an opportunity to devise primary and secondary interventions at the same time as identifying new molecular targets for treatment. This article reports the discussion and conclusion of a workshop under the auspices of the Netherlands Lung Foundation to extend our understanding of how modulation of the immune system by bacterial, parasitic, and viral infections might affect the development of asthma and to map out future lines of investigation.

The gut resistome is highly dynamic during the first months of life

AIM

We investigated the longitudinal development of several antibiotic resistance genes (ARGs) of the infant gut resistome during the first months after birth.

MATERIALS & METHODS

Fecal samples from 120 infants collected at the ages of 5, 13 and 31 weeks were analyzed and subjected to qPCR for the detection of several ARGs.

RESULTS

The prevalence of ARGs significantly increased for ermB, tetM and tetQ, while it decreased for aac(6')-aph(2'). Birth mode and breastfeeding significantly affected tetQ prevalence. Correlations to bacterial taxa suggest that fluctuations in some ARGs are (partly) attributed to shifts in bacteroides colonization rates.

CONCLUSION

Acquisition of ARGs in the gut microbiota occurs shortly after birth and resistome composition fluctuates over the course of several months, reflecting changes in microbial community structure.

Turning the inside out: the microbiology of atopic dermatitis

Allergy is on the rise worldwide. The hygiene hypothesis of atopic diseases linked microbes with atopic dermatitis (AD) both as drivers and modulators of skin pathology. The earlier literature favoured an inside-outside model of AD where an immunological abnormality compounded by a gut microbiota dysbiosis is the primary event. Probiotic intervention trials with lactobacilli and bifidobacteria as well as the application of bifidogenic oligosaccharide prebiotics showed indeed promising clinical results, but no consistent gut microbiota dysbiosis could be linked with AD. An alternative hypothesis known as outside-inside model of AD considers a genetic skin barrier effect compounded by a skin microbiota dysbiosis as primary pathogenic event. Cultivation microbiology has demonstrated strong skin colonization with superantigen-encoding Staphylococcus aureus in AD patients; microbiota and molecular microbiome analyses demonstrated that S. aureus abundance fluctuates and parallels clinical symptoms. In a mouse model, δ-toxin of S. aureus induced mast cell degranulation, leading to AD-like symptoms. Mutant mice developing AD symptoms showed increased skin colonization with S. aureus; antibiotic treatment alleviated the symptoms. Clinical trials showed that various treatments reducing S. aureus skin load also reduced AD symptoms, suggesting S. aureus as a potential critical driver of AD and a target for antimicrobial interventions other than antibiotics.

Developing Primary Intervention Strategies to Prevent Allergic Disease

Allergic diseases are a major cause of morbidity in the developed world, now affecting up to 40 % of the population with no evidence that this is abating. If anything, the prevalence of early onset allergic diseases such as eczema and food allergy appears to be still increasing. This is almost certainly due to the changing modern environment and lifestyle factors, acting to promote immune dysfunction through early perturbations in immune maturation, immune tolerance and regulation. This early propensity to inflammation may also have implications for the rising risk of other inflammatory non-communicable diseases (NCDs) later in life. Identifying risk factors and pathways for preventing early onset immune disease like allergy is likely to have benefits for many aspects of human health, particularly as many NCDs share similar risk factors. This review focuses on recent advances in primary intervention strategies for promoting early immune health and preventing allergic disease, highlighting the current evidence-based guidelines where applicable and areas requiring further investigation.

Can atopic dermatitis be prevented?

Atopic dermatitis has become a health problem in our setting due to its rising prevalence, impact on quality of life, associated costs, and role in the progression to other atopic diseases. Furthermore, atopic dermatitis has no definitive cure and therefore preventive measures are important. In this article, we review the latest advances in both primary prevention (reduction of the incidence of atopic dermatitis) and secondary prevention (reduction of associated morbidity and reduction of the atopic march). We analyze the different preventive strategies available, including modification of the immune system through microbial exposure, induction of immune tolerance through antigen exposure, and restoration of skin barrier function to halt the atopic march. Dermatologists need to be familiar with these strategies in order to apply them where necessary and to accurately inform patients and their relatives to prevent misguided or inappropriate actions.

Inflammation-associated microbiota in pediatric eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is an allergic disorder characterized by eosinophil-predominant esophageal inflammation, which can be ameliorated by food antigen restriction. Though recent studies suggest that changes in dietary composition may alter the distal gut microbiome, little is currently known about the impact of a restricted diet upon microbial communities of the oral and esophageal microenvironments in the context of EoE. We hypothesize that the oral and esophageal microbiomes of EoE patients are distinct from non-EoE controls, that these differences correspond to changes in esophageal inflammation, and that targeted therapeutic dietary intervention may influence community structure. Using 16S rRNA gene sequencing, we characterized the bacterial composition of the oral and esophageal microenvironments using oral swabs and esophageal biopsies from 35 non-EoE pediatric controls and compared this cohort to samples from 33 pediatric EoE subjects studied in a longitudinal fashion before and after defined dietary changes.

RESULTS

Firmicutes were more abundant in esophageal samples compared to oral. Proportions of bacterial communities were significantly different comparing all EoE esophageal microbiota to non-EoE controls, with enrichment of Proteobacteria, including Neisseria and Corynebacterium in the EoE cohort, and predominance of the Firmicutes in non-EoE control subjects. We detected a statistically significant difference between actively inflamed EoE biopsies and non-EoE controls. Overall, though targeted dietary intervention did not lead to significant differences in either oral or esophageal microbiota, reintroduction of highly allergenic foods led to enrichment in Ganulicatella and Campylobacter genera in the esophagus.

CONCLUSIONS

In conclusion, the esophageal microbiome in EoE is distinct from that of non-EoE controls, with maximal differences observed during active allergic inflammation.

Bacterial lysates improve the protective antibody response against respiratory viruses through Toll-like receptor 4

Respiratory viruses cause significant morbidity and mortality in infants and young children worldwide. Current strategies to modulate the immune system and prevent or treat respiratory viral infections in this age group have shown limited success. Here, we demonstrate that a lysate derived from Gram-positive and Gram-negative organisms positively modulates protective antibody responses against both respiratory syncytial virus (RSV) and influenza virus in murine models of infection. Interestingly, despite the complex mixture of Toll-like receptor (TLR) agonists present in the bacterial lysate, the modulatory effects were mostly dependent on TLR4 signaling. Our results indicate that the use of simple formulations of TLR-agonists can significantly improve the immune response against critical pediatric respiratory pathogens.

Deciphering the complexities of atopic dermatitis: shifting paradigms in treatment approaches

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease. It often precedes the development of food allergy and asthma. Recent insights into AD reveal abnormalities in terminal differentiation of the epidermal epithelium leading to a defective stratum corneum, which allows enhanced allergen penetration and systemic IgE sensitization. Atopic skin is also predisposed to colonization or infection by pathogenic microbes, most notably Staphylococcus aureus and herpes simplex virus. Causes of this abnormal skin barrier are complex and driven by a combination of genetic, environmental, and immunologic factors. These factors likely account for the heterogeneity of AD onset and the severity and natural history of this skin disease. Recent studies suggest prevention of AD can be achieved through early interventions to protect the skin barrier. Onset of lesional AD requires effective control of local and systemic immune activation for optimal management. Early intervention might improve long-term outcomes for AD and reduce the systemic allergen sensitization that leads to associated allergic diseases in the gastrointestinal and respiratory tract.

Plasmodium berghei infection ameliorates atopic dermatitis-like skin lesions in NC/Nga mice

Background

Atopic diseases are more prevalent in industrialized countries than in developing countries. In addition, significant differences in the prevalence of allergic diseases are observed between rural and urban areas within the same country. This difference in prevalence has been attributed to what is called the ‘hygiene hypothesis’. Although parasitic infections are known to protect against allergic reactions, the mechanism is still unknown. The aim of this study was to investigate whether or not malarial infections can inhibit atopic dermatitis (AD)-like skin lesions in a mouse model of AD.

Methods

We used NC/Nga mice which are a model for AD. The NC/Nga mice were intraperitoneally infected with 1 × 10⁵Plasmoduim berghei (Pb) XAT-infected erythrocytes.

Results

Malarial infections ameliorated AD-like skin lesions in the NC/Nga mice. This improvement was blocked by the administration of anti-asialo GM1 antibodies, which are anti-natural killer (NK) cells. Additionally, adoptive transfer of NK cells markedly improved AD-like skin lesions in conventional NC/Nga mice; these suggest that the novel protective mechanism associated with malaria parasitic infections is at least, in part, dependent on NK cells.

Conclusions

We have experimentally demonstrated for the first time that malarial infections ameliorated AD-like skin lesions in a mouse model of AD. Our study could explain in part the mechanism of the ‘hygiene hypothesis’, which states that parasitic infections can inhibit the development of allergic diseases.