The allergy epidemics: 1870-2010

Nicotinamide and Demographic and Disease transitions: Moderation is Best

Good health and rapid progress depend on an optimal dose of nicotinamide. Too little meat triggers the neurodegenerative condition pellagra and tolerance of symbionts such as tuberculosis (TB), risking dysbioses and impaired resistance to acute infections. Nicotinamide deficiency is an overlooked diagnosis in poor cereal-dependant economies masquerading as 'environmental enteropathy' or physical and cognitive stunting. Too much meat (and supplements) may precipitate immune intolerance and autoimmune and allergic disease, with relative infertility and longevity, via the tryptophan-nicotinamide pathway. This switch favours a dearth of regulatory T (Treg) and an excess of T helper cells. High nicotinamide intake is implicated in cancer and Parkinson's disease. Pro-fertility genes, evolved to counteract high-nicotinamide-induced infertility, may now be risk factors for degenerative disease. Moderation of the dose of nicotinamide could prevent some common diseases and personalised doses at times of stress or, depending on genetic background or age, may treat some other conditions.

Dynamic construction of gut microbiota may influence allergic diseases of infants in Southwest China

BACKGROUND

Gut microbes have been suggested as the possible targets in the management of allergic diseases. However, the way in which these microbes influence allergic diseases remain unclear. Forty-seven full-term newborns were selected from a 1000-infant birth cohort. Among them were 23 allergic infants, whereas 24 infants were healthy without allergic symptoms at 1 year of age. Two hundred and sixty-four fecal samples were collected at 7 time points following their birth. These fecal samples were microbiologically analyzed using 16S rRNA gene sequencing. The dynamic processes involved in gut microbiota diversity and composition in the tested infants were constructed.

RESULTS

Healthy infants demonstrated more statistical differences in longitudinal changes in the alpha diversity of their microbiota at the time points compared with day 0 (meconium) than did allergic infants. Analysis of beta diversity showed that the fecal microbiota of days 0 and 2 comprised different communities in healthy infants, and that there were three separate communities in the fecal microbiota of day 0 of the healthy infants, those of day 2 of the healthy infants, and those of days 0-2 of the allergic infants. The relative abundance of dominant gut microbiota at phylum level varied at different time points in the healthy and diseased groups. Bifidobacterium, Escherichia-Shigella, Streptococcus, Clostridium_sensu_stricto_1, Akkermansia and Erysipelatoclostridium were significantly different between the healthy and diseased groups at a different time points.

CONCLUSION

The dynamic construction processes of gut microbiota during early life might be associated with the occurrence of long-term allergic diseases, with the first month following birth potentially being the most critical.

Monitoring transient cell-to-cell interactions in a multi-layered and multi-functional allergy-on-a-chip system

We have developed a highly integrated lab-on-a-chip containing embedded electrical microsensors, μdegassers and pneumatically-actuated micropumps to monitor allergic hypersensitivity. Rapid antigen-mediated histamine release (e.g. s to min) and resulting muscle contraction (<30 min) is detected by connecting an immune compartment containing sensitized basophile cells to a vascular co-culture model.

Allergy in an Evolutionary Framework

Respiratory allergy including bronchial asthma and food allergy have gained epidemic character in the last decades in industrialized countries. Much has been learned with respect to the pathophysiology of allergic disease and this has facilitated specific therapies. Allergy is a chronic disease, and being so prevalent claims to search for evolutionary causes of the general susceptibility of humans as a species to react to environmental antigens in a Th2 type immune reaction with IgE production. In an evolutionary analysis of Allergy, necessary questions addressed in this review are "Why does IgE exist or why did IgE evolve?" as well as from the point of view of the mismatch hypothesis, "Why is there an Allergy epidemic?" Recent studies on the possible biological and protective role of IgE against parasites, arthropods, venoms or toxins are challenging the widely accepted definition of allergens as generally innocuous antigens. Combining the immunologic danger model and the toxin hypothesis for allergies, the allergic response could have evolved with an adaptive value and allergens could be proxies for other putative noxious agents. The last decades yielded with vast molecular data of allergens. With available bioinformatics tools, we therefore also describe that evolutionary theory could be applied to prevent allergy, estimate cross-reactivity, to design allergen-specific immunotherapy and to assess the risks of novel foods.

Staphylococcus aureus Orchestrates Type 2 Airway Diseases

Staphylococcus aureus persistently colonizes the nostrils of one-third of the population but colonizes the sinus mucosa in up to 90% of patients with nasal polyps, implying a possible role in airway disease. Recent findings give new mechanistic insights into the ability of S. aureus to trigger type 2 inflammatory responses in the upper and lower airways. This novel concept of a S. aureus-driven chronic airway inflammatory disease suggests a new understanding of disease triggers. This article reviews the role of S. aureus in chronic inflammatory airway diseases and discusses possible therapeutic approaches to target S. aureus.

Early onset food protein-induced enterocolitis syndrome in two breastfed newborns masquerading as surgical diseases: case reports and literature review

Background: Food protein-induced enterocolitis syndrome (FPIES) is a non-immunoglobulin E cell-mediated gastrointestinal food allergy that primarily presents in infancy, as early as the first hours of life. FPIES is often misdiagnosed as sepsis, severe gastroenteritis, abdominal surgical emergency or even metabolic, neurologic, or cardiac disorders.Methods: We report two neonatal cases of cow's milk protein (CMP)-induced FPIES masquerading as surgical diseases. Our purpose is to highlight the diagnostic difficulties in FPIES in this age group and to provide further evidence of the important role played by the prenatal environment in the development of allergic diseases.Results: Case 1 is a 2-day-old boy born at 35th + 5 weeks of gestation admitted to our Neonatal Intensive Care Unit (NICU) for bloody diarrhea who started presenting apnea, crying, pallor, jaundice, and abdominal tenderness. Case 2 is a 3-day-old boy born at 38th +5 weeks of gestation admitted to our NICU for repeated bilious vomiting. Both patients were administered infant formula in the first hours of life, thereafter they received only breast milk. In both cases, CMP allergy was finally suspected and an extensively hydrolyzed formula was administered with the resolution of symptoms. A diagnosis of CMP-induced FPIES was made.Conclusions: FPIES is a heterogeneous disorder. Severe forms of FPIES could be mistaken for surgical diseases, such as necrotizing enterocolitis. A trial of food elimination should be considered whenever diagnostic tests are inconclusive. FPIES must be suspected even in breastfed infants.

[Environmental risk factors for asthma developement]

The prevalence of asthma has increased rapidly since the early 1970s, and only changes in exposure to environmental factors; which go together with changes in lifestyle, are likely to explain such a rapid increase. Exposure to allergens is a risk factor for allergic sensitization, and allergic sensitization is a risk factor for allergic asthma. However, apart from indoor mold exposure as a risk factor for childhood asthma, there is insufficient evidence to conclude that the associations between allergen exposure and asthma development are causal. A new challenge for research is to analyze the huge amount of data derived from the metagenomic characterization of the environmental and human microbiome, to understand the role of interactions between viruses, bacteria and allergens in the development of asthma. It is recognized that prenatal and postnatal exposure to air pollution and maternal smoking increase the risk of developing asthma in children. In adults, the data are scarce and the results remain controversial as regards these exposures and asthma incidence. Further research is needed to appraise the effect of exposure to phenols, phthalates and perfluorinated compounds, which are widespread in the environment and may be associated with asthma, especially in children. Frequent use of chemicals for home cleaning especially in the form of sprays - which is a common practice at the population level - is a risk factor for the development of adult asthma. The domestic use of cleaning products might also be a risk factor for asthma in children exposed at home. The chemicals involved in these relationships are still to be identified. Occupational asthma is a major phenotype of adult asthma. A significant part of these asthma cases might relate to occupational exposure to cleaning products. While there is evidence of associations between diet during pregnancy or during childhood and the risk of developing asthma in children, the data in adults are insufficient. Beyond genetic factors, body composition is influenced by dietary choices and physical activity. Further research is needed to clarify the complex interplay between these nutritional factors and asthma development. The new challenge for research is to decipher the role of all the environmental factors to which the individual is exposed since conception ("exposome") in the development of asthma, using a holistic approach.

Advances in Molecular Mechanisms of Wheat Allergenicity in Animal Models: A Comprehensive Review

The prevalence of wheat allergy has reached significant levels in many countries. Therefore, wheat is a major global food safety and public health issue. Animal models serve as critical tools to advance the understanding of the mechanisms of wheat allergenicity to develop preventive and control methods. A comprehensive review on the molecular mechanisms of wheat allergenicity using animal models is unavailable at present. There were two major objectives of this study: To identify the lessons that animal models have taught us regarding the molecular mechanisms of wheat allergenicity and to identify the strengths, challenges, and future prospects of animal models in basic and applied wheat allergy research. Using the PubMed and Google Scholar databases, we retrieved and critically analyzed the relevant articles and excluded celiac disease and non-celiac gluten sensitivity. Our analysis shows that animal models can provide insight into the IgE epitope structure of wheat allergens, effects of detergents and other chemicals on wheat allergenicity, and the role of genetics, microbiome, and food processing in wheat allergy. Although animal models have inherent limitations, they are critical to advance knowledge on the molecular mechanisms of wheat allergenicity. They can also serve as highly useful pre-clinical testing tools to develop safer genetically modified wheat, hypoallergenic wheat products, novel pharmaceuticals, and vaccines.

Environmental exposures during pregnancy: Mechanistic effects on immunity

In human studies, it is well established that exposures during embryonic and fetal development periods can influence immune health. Coupled with genetic predisposition, these exposures can alter lifetime chronic and infectious disease trajectory, and, ultimately, life expectancy. Fortunately, as research advances, mechanisms governing long-term effects of prenatal exposures are coming to light and providing the opportunity for intervention and risk reduction. For instance, human association studies have provided a foundation for the association of prenatal exposure to particulate matter with early immunosuppression and later allergic disease in the offspring. Only recently, the mechanisms mediating this response have been revealed and there is much we have yet to discover. Although cellular immune response is understood for many exposure scenarios, molecular pathways are still unidentified. This review will provide commentary and synthesis of the current literature regarding environmental exposures during pregnancy and mechanisms determining immune outcomes. Shared mechanistic features and current gaps in the state of the science are identified and discussed. To such purpose, we address exposures by their immune effect type: immunosuppression, autoimmunity, inflammation and tissue damage, hypersensitivity, and general immunomodulation.

Delineation of the Individual Effects of Vitamin E Isoforms on Early Life Incident Wheezing

OBJECTIVES

To test the hypothesis that maternal plasma alpha-tocopherol levels are associated with protection from childhood wheeze and that this protection is modified by gamma-tocopherol.

STUDY DESIGN

We conducted a prospective nested study in the Infant Susceptibility to Pulmonary Infections and Asthma Following Respiratory Syncytial Virus Exposure birth cohort of 652 children with postpartum maternal plasma vitamin E isoforms used as a surrogate for pregnancy concentrations. Our outcomes were wheezing and recurrent wheezing over a 2-year period, ascertained using validated questionnaires. We assessed the association of alpha- and gamma-tocopherol with wheezing outcomes using multivariable adjusted logistic regression, and tested for interaction between the isoforms with respect to the risk for wheezing outcomes.

RESULTS

Children with wheezing (n = 547, n = 167; 31%) and recurrent wheezing (n = 545, n = 55; 10.1%) over a 2-year period were born to mothers with significantly lower postpartum maternal plasma concentrations of alpha-tocopherol, P = .016 and P = .007, respectively. In analyses of IQR increases, alpha-tocopherol was associated with decreased risk of wheezing (aOR 0.70 [95% CI 0.53,0.92]) and recurrent wheezing (aOR 0.63 [95% CI 0.42,0.95]). For gamma-tocopherol, the aOR for wheezing was 0.79 (95% CI 0.56-1.10) and the aOR for recurrent wheezing was 0.56 (95% CI 0.33-0.94, with nonmonotonic association). The association of alpha-tocopherol with wheezing was modified by gamma-tocopherol (P interaction = .05).

CONCLUSIONS

Increases in postpartum maternal plasma alpha-tocopherol isoform concentrations were associated with decreased likelihood of wheezing over a 2-year period. Gamma-tocopherol modified this association.

Selective citation in the literature on the hygiene hypothesis: a citation analysis on the association between infections and rhinitis

OBJECTIVE

Our objective was to assess the occurrence and determinants of selective citation in scientific publications on Strachan's original hygiene hypothesis. His hypothesis states that lack of exposure to infections in early childhood increases the risk of rhinitis.

SETTING

Web of Science Core Collection.

PARTICIPANTS

We identified 110 publications in this network, consisting of 5551 potential citations.

PRIMARY AND SECONDARY OUTCOME MEASURES

Whether a citation occurs or not, measured and analysed according to the preregistered protocol.

RESULTS

We found evidence for citation bias in this field: publications supportive of the hypothesis were cited more often than non-supportive publications (OR adjusted for study design [adjOR] 2.2, 95% CI 1.6 to 3.1), and the same was the case for publications with mixed findings (adjOR 3.1, 95% CI 2.2 to 4.5). Other relevant determinants for citation were type of exposure, specificity, journal impact factor, authority and self-citation. Surprisingly, prospective cohort studies were cited less often than other empirical studies.

CONCLUSIONS

There is clear evidence for selective citation in this research field, and particularly for citation bias.

Regulation of Interaction between the Upper and Lower Airways in United Airway Disease

The concept of united airway disease comprises allergic rhinitis (AR) with asthma, and eosinophilic chronic rhinosinusitis (ECRS) with asthma. It embodies a comprehensive approach to the treatment of upper and lower airway inflammation. The treatment of upper airway inflammation reduces asthma symptoms and decreases the dose of inhaled corticosteroids (ICS) necessary to treat asthma. However, little is known about the mechanisms of interaction between upper and lower airway inflammation. Here we review these mechanisms, focusing on neural modulation and introduce a novel therapeutic approach to united airway disease using a fine-particle ICS. Our understanding of the relationship between the upper and lower airways and its contribution to T helper 2 (Th2)-skewed disease, such as AR and/or ECRS with asthma, has led us to this novel therapeutic strategy for a comprehensive approach to the treatment of upper airway inflammation with asthma.

Environmental exposures and mechanisms in allergy and asthma development

Environmental exposures interplay with human host factors to promote the development and progression of allergic diseases. The worldwide prevalence of allergic disease is rising as a result of complex gene-environment interactions that shape the immune system and host response. Research shows an association between the rise of allergic diseases and increasingly modern Westernized lifestyles, which are characterized by increased urbanization, time spent indoors, and antibiotic usage. These environmental changes result in increased exposure to air and traffic pollution, fungi, infectious agents, tobacco smoke, and other early-life and lifelong risk factors for the development and exacerbation of asthma and allergic diseases. It is increasingly recognized that the timing, load, and route of allergen exposure affect allergic disease phenotypes and development. Still, our ability to prevent allergic diseases is hindered by gaps in understanding of the underlying mechanisms and interaction of environmental, viral, and allergen exposures with immune pathways that impact disease development. This Review highlights epidemiologic and mechanistic evidence linking environmental exposures to the development and exacerbation of allergic airway responses.

Differential bronchial epithelial response regulated by ΔNp63: a functional understanding of the epithelial shedding found in asthma

Bronchial epithelial cells serve as a physical barrier at the forefront of the immune system. Barrier disruption and an excessive immune response of the bronchial epithelium contribute to the pathophysiology of asthma, a chronic bronchial inflammatory disease. The purpose of this study was to investigate the functional significance of ΔNp63, a p53-like transcription factor expressed by the basal bronchial epithelium. The immunohistochemical expression profile of ΔNp63 was evaluated in human bronchial tissue derived from asthma patients. The role of ΔNp63 in apoptosis inhibition and production of soluble mediators was investigated in vitro with cultured BEAS-2B bronchial epithelial cells using molecular biological analysis. In healthy bronchial tissue, ΔNp63-positive basal epithelial cells were covered with differentiated ΔNp63-negative cells but in the asthmatic airway, ΔNp63-positive cells were directly exposed to the bronchial lumen due to severe epithelial shedding. ΔNp63 regulated bronchial apoptosis in response to Toll-like receptor 3 stimulation. On the other hand, expression of ΔNp63 was modulated by stimulation with trypsin and SLIGKV, protease-activated receptor 2 ligands. Further phenotypic analysis revealed that ΔNp63 controlled the transcriptional expression and protein release of some epithelium-derived proinflammatory cytokines and endogenous protease inhibitors. We conclude that ΔNp63 modulates the bronchial epithelial response to viral infection. At the same time, ΔNp63 expression is influenced by proteases, which are abundant in house dust mites. Therefore, the ΔNp63 axis would be intimately involved in these two major triggers of asthma exacerbations, viral infection and protease overload.

Current Trends in Tolerance Induction in Cow's Milk Allergy: From Passive to Proactive Strategies

This review addresses the current strategies of inducing tolerance development in infant and childhood cow's milk protein allergy (CMPA). The change in prevention strategies for CMPA has been emphasized based on the lack of evidence to support the efficacy of food allergen avoidance in infancy and the concept of the dual-allergen-exposure hypothesis, which suggests that allergen exposure through the skin leads to sensitization, whereas early oral consumption of allergenic food protein induces oral tolerance. The new approach is based on the likelihood of early introduction of allergenic foods to the infant's diet to reduce the development of food allergies through oral tolerance induction. The latest treatment guidelines recommend the continuation of breast feeding and the elimination of cow's milk and products from the maternal diet in exclusively breast-fed infants with CMPA, the use of an extensively hydrolyzed infant formula (eHF) with proven efficacy in CMPA as the first elimination diet in formula-fed infants with CMPA and the use of amino acid-based formula (AAF) in severe cases, such as anaphylaxis, enteropathy, eosinophilic esophagitis, and food protein-induced enterocolitis syndrome (FPIES), as well as cases of multiple system involvement, multiple food allergies, and intolerance to extensively hydrolyzed formula (eHF). In conclusion, this paper presents the current knowledge on tolerance development in infants and children with CMPA to increase the awareness of the clinicians concerning the new approaches in CMPA treatment Tolerance development is considered a relatively new concept in CMPA, inducing a shift in interventions in CMPA from a passive (avoidance of responsible allergen) toward a proactive (tolerance induction) strategy.

Maternal Allergy Status Has No Impact on Neonatal Immune Responses to Allergen Stimuli

Due to the increasing incidence of allergic diseases, there is a strong need to identify a prognostic marker pointing to increased risk of allergy development allowing introduction of early preventive measures. Cord blood seems to be a good source for searching for such marker. The capacity of cord blood cells to respond to common allergens could point to increased predisposition to later allergy development. In our study, cytokines typical of Th1 (IFN-γ), Th2 (IL-5, IL-13) and Treg (IL-10) immune responses were followed at both the level of gene expression and cytokine secretion in cord blood cells of newborns of healthy mothers (children with relatively low risk of allergy development) and allergic mothers (children with relatively high risk of allergy development) stimulated by allergens (pollen from birch and timothy grass, house dust mite, ovalbumin). We have not observed any difference in the response of cord blood cells of neonates of healthy and allergic mothers to allergen in vitro. Both gene expression and secretion of cytokines in response to allergen stimulation were comparable with the unstimulated controls. It seems that early postnatal events will be more decisive for future allergy development than prenatal sensitization of the foetal immune system with allergen in utero in allergic mothers.

Der p 5 allergen from house dust mite: first epitope mapping of rabbit IgG blocking antibodies

Der p 5 is one of the important house dust mite allergens in Algeria; this allergen is frequently recognized by patients with allergic asthma. However, there is no information on its IgG-binding epitopes. In the present study, rabbits were immunized with recombinant Der p 5 allergen, and serum samples were obtained. Recognition of linear IgG epitopes of Der p 5 was determined using synthesized peptides derived from the allergen sequence. The results showed that serum from immunized rabbits recognized three linear epitopes from Der p 5 (28EDKKHDYQNEFDFLLMERIHEQIK43), (37IHEQIKKGELALFYLQEQ55) and (92LMQRKDLDIFEQYNLEMAKKS112). More interestingly, we observed that the 92L-S112 amino acid sequence is well recognized by both IgE and IgG antibodies. Der p 5 stimulates the synthesis of specific IgG antibodies which recognize common but also novel epitopes compared to IgE antibody binding. Indeed, the potential to induce IgG antibodies can be used to inhibit human IgE binding to allergens which may be part of the mechanism of action of specific immunotherapy.

Dietary intake of fish and ω-3 polyunsaturated fatty acids and physician-diagnosed allergy in Japanese population: The Japan Environment and Children's Study

OBJECTIVE

Emerging evidence from epidemiologic studies and clinical trials indicates that ω-3 polyunsaturated fatty acids (PUFAs) may have a preventive or therapeutic effect on allergy, although the results remain controversial. The aim of this study was to investigate the association between intake of fish and ω-3 PUFAs with risk for lifetime prevalence of physician-diagnosed allergy in a Japanese population.

METHODS

Study participants were 78 621 pregnant women and 42 831 male partners from The Japan Environment and Children's Study. History of physician-diagnosed allergy (asthma, allergic rhinitis/pollinosis, allergic conjunctivitis, or atopic dermatitis) was determined by self-administered questionnaire survey. Dietary intake of fish and ω-3 PUFAs was estimated using a food frequency questionnaire.

RESULTS

Contrary to our hypothesis, an increased risk for allergy was found by multivariable logistic regression in females, especially in allergic rhinitis/pollinosis, allergic conjunctivitis, or atopic dermatitis for fish intake and in allergic rhinitis/pollinosis or allergic conjunctivitis for ω-3 PUFAs. As for male partners, risk for allergic rhinitis/pollinosis or atopic dermatitis was increased for both fish and ω-3 PUFA intake. No statistically significant results were observed for the risk for asthma in either women or men.

CONCLUSION

Fish and ω-3 PUFA intake were associated with increased risk for some allergic diseases. Further research is warranted to confirm these findings in individuals with high fish consumption.

Ascariasis as a model to study the helminth/allergy relationships

Ascariasis is the most frequent soil transmitted helminthiasis and, as well as other helminth infections, is expected to influence the clinical presentation of allergic diseases such as asthma. Indeed, several clinical and experimental works have shown an important impact either increasing or suppressing symptoms, and the same effects have been detected on the underlying immune responses. In this review we analyze the work on this field performed in Colombia, a Latin American tropical country, including aspects such as the molecular genetics of the IgE response to Ascaris; the allergenic activity of Ascaris IgE-binding molecular components and the immunological and clinical influences of ascariasis on asthma. The analysis allows us to conclude that the impact of ascariasis on the inception and evolution of allergic diseases such as asthma deserves more investigation, but advances have been made during the last years. The concurrent parasite-induced immunostimulatory and immunosuppressive effects during this helminthiasis do modify the natural history of asthma and some aspects of the practice of allergology in the tropics. Theoretically it can also influence the epidemiological trends of allergic diseases either by its absence or presence in different regions and countries.

Antigen-specific regulatory T-cell responses against aeroantigens and their role in allergy

The mucosal immune system of the respiratory tract is specialized to continuously monitor the external environment and to protect against invading pathogens, while maintaining tolerance to innocuous inhaled particles. Allergies result from a loss of tolerance against harmless antigens characterized by formation of allergen-specific Th2 cells and IgE. Tolerance is often described as a balance between harmful Th2 cells and various types of protective "regulatory" T cells. However, the identity of the protective T cells in healthy vs. allergic individuals or following successful allergen-specific therapy is controversially discussed. Recent technological progress enabling the identification of antigen-specific effector and regulatory T cells has significantly contributed to our understanding of tolerance. Here we discuss the experimental evidence for the various tolerance mechanisms described. We try to integrate the partially contradictory data into a new model proposing different mechanism of tolerance depending on the quality and quantity of the antigens as well as the way of antigen exposure. Understanding the basis of tolerance is essential for the rational design of novel and more efficient immunotherapies.

Does clinical outcome of birch pollen immunotherapy relate to induction of blocking antibodies preventing IgE from allergen binding? A pilot study monitoring responses during first year of AIT

Background

The clinical benefit of allergen-specific immunotherapy (AIT) involves induction of blocking antibodies. It is not clear if these antibodies function via steric hindrance alone or a combination of levels, avidities, and epitope specificities, and clinical outcome cannot be predicted. We aim to in-depth characterize serum antibody profiles during birch pollen AIT, investigate therapy-induced antibodies for their capacity to block IgE binding to Bet v 1 and correlate data with clinical outcomes.

Methods

Immune responses of five birch pollen allergic patients were monitored during the first year of AIT by nasal provocation tests (NPTs), ImmunoCAP, immunoblots, direct and avidity enzyme-linked immunosorbent assays, mediator release assays, facilitated antigen binding (FAB) assays, and inhibition mediator release assays.

Results

There was no correlation between NPT results and therapy-induced changes in levels (IgE, IgG, IgA, IgM), avidities, or mediator release potency of Bet v 1-specific antibodies. In FAB assays, blocking antibodies initiated upon AIT were shown to prevent formation of Bet v 1-IgE complexes of an indicator serum pool and significantly correlated with clinical readout. Inhibition mediator release assays using patient-specific IgE for passive sensitization revealed therapy-induced blocking capacities with very good correlation to NPT results. Notably, this assay was the only one to detect a non-responder during treatment in this pilot study.

Conclusions

Clinical outcome of AIT depends on induction of blocking antibodies able to prevent the patient’s own IgE from allergen binding. Monitoring of clinical efficacy seems to be best achieved using the inhibition mediator release assay, as development of relevant blocking antibodies can be verified in a patient-tailored manner.

Electronic supplementary material

The online version of this article (10.1186/s13601-018-0226-7) contains supplementary material, which is available to authorized users.

Atopic dermatitis in cats and dogs: a difficult disease for animals and owners

The purpose of this review article is to give an overview of atopic dermatitis in companion animals and of recent developments including knowledge on immunological background, novel treatment options and difficulties in disease management. The prevalence of hypersensitivities seems to be increasing. The pathogenetic mechanisms are not fully understood, yet multiple gene abnormalities and altered immunological processes are involved. In dogs and cats, the diagnosis of atopic dermatitis is based on history, clinical examination and exclusion of other differential diagnoses. Intradermal testing or testing for serum allergen-specific Immunoglobulin E is only used to identify allergens for inclusion in the extract for allergen immunotherapy. Symptomatic therapy includes glucocorticoids, ciclosporin, essential fatty acids and antihistamines. A selective janus kinase 1 inhibitor and a caninized monoclonal interleukin-31 antibody are the newest options for symptomatic treatment, although longterm effects still need to be assessed. The chronic and often severe nature of the disease, the costly diagnostic workup, frequent clinical flares and lifelong treatment are challenging for owners, pets and veterinarians. Patience and excellent communication skills are needed to achieve a good owner compliance and satisfactory clinical outcome for the animal.

Immune suppression of food allergy by maternal IgG in murine models

BACKGROUND

Most of the patients develop food allergy early in life. The factors related to parental immune condition might be one of the conceivable causes.

METHODS

We reported murine models of food allergy and oral OVA tolerance. To investigate the influence of parental immune condition on infant food allergy, female and male mice with food allergy or oral tolerance were mated with each other.

RESULTS

Food allergy was suppressed by decreased IgE production in the offspring of mice with food allergy. On the contrary, anaphylaxis for OVA was induced in the offspring of mice with oral tolerance. The suppression of food allergy being dependent on a maternal factor was revealed in the offspring after cross-mating mice with food allergy and oral tolerance. Because OVA-specific IgG, presumed to be from the allergic mother, was detected in the serum of naïve infants from mothers allergic to food, we assumed that the suppression was dependent on a specific IgG. The serum IgG purified by a G-protein column was administered before OVA sensitization in the food allergy model, and OVA-specific IgE production was found to be diminished in the administered mice. However, OVA-specific monoclonal IgG₁ and IgG_2a administration could not suppress food allergy. Because we detected OVA-IgG immune complex in the serum of mothers allergic to food, it might be a cause of maternal immune suppression.

CONCLUSIONS

We demonstrated that maternal specific IgG conjugated food antigen is an important factor related to the development of food allergy and acquiring tolerance.

Bedroom Allergen Exposure Beyond House Dust Mites

PURPOSE OF REVIEW

The review provides insight into recent findings on bedroom allergen exposures, primarily focusing on pet, pest, and fungal exposures.

RECENT FINDINGS

Large-scale studies and improved exposure assessment technologies, including measurement of airborne allergens and of multiple allergens simultaneously, have extended our understanding of indoor allergen exposures and their impact on allergic disease. Practical, streamlined methods for exposure reduction have shown promise in some settings, and potential protective effects of early-life exposures have been further elucidated through the investigation of specific bacterial taxa. Advances in molecular allergology have yielded novel data on sensitization profiles and cross-reactivity. The role of indoor allergen exposures in allergic disease is complex and remains incompletely understood. Advancing our knowledge of various co-exposures, including the environmental and host microbiome, that interact with allergens in early life will be crucial for the development of efficacious interventions to reduce the substantial economic and social burden of allergic diseases including asthma.

Orally Administered Phlorotannins from Eisenia arborea Suppress Chemical Mediator Release and Cyclooxygenase-2 Signaling to Alleviate Mouse Ear Swelling

Phlorotannin is the collective term for polyphenols derived from brown algae belonging to the genera Ascopyllum, Ecklonia, Eisenia, Fucus and Sargassum etc. Since the incidence of allergies is currently increasing in the world, there is a focus on phlorotannins having anti-allergic and anti-inflammatory effects. In this study, six purified phlorotannins (eckol; 6,6'-bieckol; 6,8'-bieckol; 8,8'-bieckol; phlorofucofuroeckol (PFF)-A and PFF-B) from Eisenia arborea, orally administered to mice, were examined for their suppression effects on ear swelling. In considering the suppression, we also examined whether the phlorotannins suppressed release of chemical mediators (histamine, leukotriene B₄ and prostaglandin E₂), and mRNA expression and/or the activity of cyclooxygenase-2 (COX-2), using RBL-2H3 cells, a cultured mast cell model. Results showed that the phlorotnannins exhibited suppression effects in all experiments, with 6,8'-bieckol, 8,8'-bieckol and PFF-A showing the strongest of these effects. In conclusion, orally administered phlorotannins suppress mouse ear swelling, and this mechanism apparently involves suppression of chemical mediator release and COX-2 mRNA expression or activity. This is the first report of the anti-allergic effects of the orally administered purified phlorotannins in vivo. Phlorotannins show potential for use in functional foods or drugs.

Microbial Insights into Asthmatic Immunopathology. A Forward-Looking Synthesis and Commentary

Asthma is an aberrant inflammatory condition of the airways affecting approximately 1 in 10 children in affluent countries. An increasing body of evidence suggests that microbial exposures during a "critical window" of development in early life play a central role in determining future asthma susceptibility. However, like the disease itself, considerable heterogeneity exists among studies in which researchers have investigated the associations between particular microbial taxa and asthma immunology. As our understanding of asthmatic pathology evolves to enable clearer definition of asthma endotypes, it will be important to consider the impact of various environmental factors on each endotype. Given the strong evidence in support of the hypothesis that early-life microbial exposures predict later disease states such as asthma, consideration of these endotypes when establishing experimental outcomes in epidemiological studies could allow for increased precision when determining exposure-outcome associations and engaging in more focused follow-up mechanistic investigations.

Microbiome and Allergic Diseases

Allergic diseases, such as respiratory, cutaneous, and food allergy, have dramatically increased in prevalence over the last few decades. Recent research points to a central role of the microbiome, which is highly influenced by multiple environmental and dietary factors. It is well established that the microbiome can modulate the immune response, from cellular development to organ and tissue formation exerting its effects through multiple interactions with both the innate and acquired branches of the immune system. It has been described at some extent changes in environment and nutrition produce dysbiosis in the gut but also in the skin, and lung microbiome, inducing qualitative and quantitative changes in composition and metabolic activity. Here, we review the potential role of the skin, respiratory, and gastrointestinal tract (GIT) microbiomes in allergic diseases. In the GIT, the microbiome has been proven to be important in developing either effector or tolerant responses to different antigens by balancing the activities of Th1 and Th2 cells. In the lung, the microbiome may play a role in driving asthma endotype polarization, by adjusting the balance between Th2 and Th17 patterns. Bacterial dysbiosis is associated with chronic inflammatory disorders of the skin, such as atopic dermatitis and psoriasis. Thus, the microbiome can be considered a therapeutical target for treating inflammatory diseases, such as allergy. Despite some limitations, interventions with probiotics, prebiotics, and/or synbiotics seem promising for the development of a preventive therapy by restoring altered microbiome functionality, or as an adjuvant in specific immunotherapy.

Converging findings from linkage between periodontal pathogen with atopic and allergic immune response

This study aims to explore a relationship between exposures of whole-cell Porphyromonas gingivalis in various doses with atopic inflammatory responses at experimental mice. A pretest-posttest controlled group design, with 16 Wistar rats (Rattus novergicus) randomized into four groups. Group 1 was the control group. Group 2 was given low-dose (9 × 10⁷ colony-forming unit) of P. gingivalis. Group 3 was given medium-dose (9 × 10⁹ colony-forming unit) of P. gingivalis. Group 4 was given high-dose (9 × 10¹¹ colony-forming unit) of P. gingivalis. Interleukin-4, Interleukin-5, Interleukin-17F, Interleukin-21, Immunoglobulin-E, Immunoglobulin-G₄, and γ-Interferon were measured by direct-sandwich ELISA just before the treatments began, day-4, and day-11 after treatments. There is a sudden increase of Interleukin-4 in the group 4 (23.79 ± 0.91 pg/ml to 54.17 ± 0.79 pg/ml; p = 0.01) and slight increase of Interleukin-5 in the group 4 (207.60 ± 11.15 pg/ml to 243.40 ± 9.33 pg/ml; p = 0.03). No change was observed for Interleukin-17F in all groups. Serum concentration of Immunoglobulin-E was decreased in group 2 (-10.44 ± 8.13 pg/ml), but increased in group 4 (+1.03 ± 4.57 pg/ml). Taken together, some cytokines are up-regulated and others are down-regulated after exposure to whole-cell P. gingivalis. Moreover, study of host responses during periodontal infection may offer critical key insight that contribute to the development of atopy. CLINICAL IMPLICATIONS: We introduced and explained the potential role of periodontal pathogen Porphyromonas gingivalis in systemic immune responses, along with its virulence factor inside the oral cavity. Our results consider several changes and differences of cytokines and immunoglobulins following whole-cell Porphyromonas gingivalis exposure. However, results of the study need to be interpreted with caution due to its limitations. CAPSULE SUMMARY: Interleukin (IL)-4 and IL-5 had been found increase after exposure to the periodontal pathogens Porphyromonas gingivalis, whereas no or minimal change had been found in the level of IL-17F, Ig-G₄, and IFN-γ. The various cytokines and immunoglobulins shown in this study do not prove a causal relationship, and the precise role of Porphyromonas gingivalis in the regulation of atopic immune response warrants further investigation. Nevertheless, these findings may provide some critical key insight into the host responses following Porphyromonas gingivalis infection.

The impact of modifiable risk factor reduction on childhood asthma development

Childhood asthma is responsible for significant morbidity and health care expenditures in the United States. The incidence of asthma is greatest in early childhood, and the prevalence is projected to continue rising in the absence of prevention and intervention measures. The prevention of asthma will likely require a multifaceted intervention strategy; however, few randomized controlled trials have assessed such approaches. The purpose of this review was to use previous meta-analyses to identify the most impactful risk factors for asthma development and evaluate the effect of risk factor reduction on future childhood asthma prevalence. Common and modifiable risk factors with large effects included acute viral respiratory infections, antibiotic use, birth by cesarean section, nutritional disorders (overweight, obesity), second hand smoke exposure, allergen sensitization, breastfeeding, and sufficient prenatal vitamin D level. Evaluation and estimates of risk factor modification on populations at risk should guide scientists and policymakers toward high impact areas that are apt for additional study and intervention.

Association Between Use of Acid-Suppressive Medications and Antibiotics During Infancy and Allergic Diseases in Early Childhood

IMPORTANCE

Allergic diseases are prevalent in childhood. Early exposure to medications that can alter the microbiome, including acid-suppressive medications and antibiotics, may influence the likelihood of allergy.

OBJECTIVE

To determine whether there is an association between the use of acid-suppressive medications or antibiotics in the first 6 months of infancy and development of allergic diseases in early childhood.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was conducted in 792 130 children who were Department of Defense TRICARE beneficiaries with a birth medical record in the Military Health System database between October 1, 2001, and September 30, 2013, with continued enrollment from within 35 days of birth until at least age 1 year. Children who had an initial birth stay of greater than 7 days or were diagnosed with any of the outcome allergic conditions within the first 6 months of life were excluded from the study. Data analysis was performed from April 15, 2015, to January 4, 2018.

EXPOSURES

Exposures were defined as having any dispensed prescription for a histamine-2 receptor antagonist (H2RA), proton pump inhibitor (PPI), or antibiotic.

MAIN OUTCOMES AND MEASURES

The main outcome was allergic disease, defined as the presence of food allergy, anaphylaxis, asthma, atopic dermatitis, allergic rhinitis, allergic conjunctivitis, urticaria, contact dermatitis, medication allergy, or other allergy.

RESULTS

Of 792 130 children (395 215 [49.9%] girls) included for analysis, 60 209 (7.6%) were prescribed an H2RA, 13 687 (1.7%) were prescribed a PPI, and 131 708 (16.6%) were prescribed an antibiotic during the first 6 months of life. Data for each child were available for a median of 4.6 years. Adjusted hazard ratios (aHRs) in children prescribed H2RAs and PPIs, respectively, were 2.18 (95% CI, 2.04-2.33) and 2.59 (95% CI, 2.25-3.00) for food allergy, 1.70 (95% CI, 1.60-1.80) and 1.84 (95% CI, 1.56-2.17) for medication allergy, 1.51 (95% CI, 1.38-1.66) and 1.45 (95% CI, 1.22-1.73) for anaphylaxis, 1.50 (95% CI, 1.46-1.54) and 1.44 (95% CI, 1.36-1.52) for allergic rhinitis, and 1.25 (95% CI, 1.21-1.29) and 1.41 (95% CI, 1.31-1.52) for asthma. The aHRs after antibiotic prescription in the first 6 months of life were 2.09 (95% CI, 2.05-2.13) for asthma, 1.75 (95% CI, 1.72-1.78) for allergic rhinitis, 1.51 (95% CI, 1.38-1.66) for anaphylaxis, and 1.42 (95% CI, 1.34-1.50) for allergic conjunctivitis.

CONCLUSIONS AND RELEVANCE

This study found associations between the use of acid-suppressive medications and antibiotics during the first 6 months of infancy and subsequent development of allergic disease. Acid-suppressive medications and antibiotics should be used during infancy only in situations of clear clinical benefit.

Expert clinician's perspectives on environmental medicine and toxicant assessment in clinical practice

Background

Most clinicians feel ill-equipped to assess or educate patients about toxicant exposures, and it is unclear how expert environmental medicine clinicians assess these exposures or treat exposure-related conditions. We aimed to explore expert clinicians’ perspectives on their practice of environmental medicine to determine the populations and toxicants that receive the most attention, identify how they deal with toxicant exposures and identify the challenges they face and where they obtain their knowledge.

Methods

A qualitative study involving semi-structured interviews with expert environmental clinicians in Australia and New Zealand was conducted. Interviews were recorded and transcribed, and themes were identified and collated until no new themes emerged.

Results

Five dominant themes emerged from 16 interviews: (1) environmental medicine is a divided profession based on type of practice, patient cohort seen and attitudes towards nutrition and exposure sources; (2) clinical assessment of toxicant exposures is challenging; (3) the environmental exposure history is the most important clinical tool; (4) patients with environmental sensitivities are increasing, have unique phenotypes, are complex to treat and rarely regain full health; and (5) educational and clinical resources on environmental medicine are lacking.

Conclusions

Environmental medicine is divided between integrative clinicians and occupational and environmental physicians based on their practice dynamics. All clinicians face challenges in assessing toxicant loads, and an exposure history is seen as the most useful tool. Standardised exposure assessment tools have the potential to significantly advance the clinical practice of environmental medicine and expand its reach across other clinical disciplines.

Speculation as to why the Frequency of Eosinophilic Esophagitis Is Increasing

PURPOSE OF REVIEW

The frequency of eosinophilic esophagitis (EoE), an immune/antigen-mediated disorder first described in 1993, has been increasing rapidly. The purpose of this review is to consider hypotheses proposed to explain this increase and to speculate on their validity.

RECENT FINDINGS

The hygiene hypothesis attributes the rise of EoE to modern hygienic conditions resulting in fewer childhood infections with microbes that might have protected against allergy development. Microbial dysbiosis, a change in the microbiome's composition and diversity caused by a modern affluent lifestyle, also might contribute to allergic conditions. Environmental factors including modern chemicals contaminating crops, livestock treated with hormones and antibiotics, food additives and processing changes, and pollutants in the air and water conceivably might predispose to EoE. One intriguing hypothesis attributes increasing EoE to increasing use of acid-suppressive medications like proton pump inhibitors, which might prevent peptic digestion of food allergens, increase gastric permeability, and alter the microbiome to favor food allergy development. In a recent pediatric case-control study, use of acid suppressants in infancy was by far the single strongest risk factor identified for later development of EoE. It remains unclear which, if any, of the above factors underlies the rising frequency of EoE. These factors need not be mutually exclusive, and the cause of EoE may well be multifactorial.

Speculation as to why the Frequency of Eosinophilic Esophagitis Is Increasing

PURPOSE OF REVIEW

The frequency of eosinophilic esophagitis (EoE), an immune/antigen-mediated disorder first described in 1993, has been increasing rapidly. The purpose of this review is to consider hypotheses proposed to explain this increase and to speculate on their validity.

RECENT FINDINGS

The hygiene hypothesis attributes the rise of EoE to modern hygienic conditions resulting in fewer childhood infections with microbes that might have protected against allergy development. Microbial dysbiosis, a change in the microbiome's composition and diversity caused by a modern affluent lifestyle, also might contribute to allergic conditions. Environmental factors including modern chemicals contaminating crops, livestock treated with hormones and antibiotics, food additives and processing changes, and pollutants in the air and water conceivably might predispose to EoE. One intriguing hypothesis attributes increasing EoE to increasing use of acid-suppressive medications like proton pump inhibitors, which might prevent peptic digestion of food allergens, increase gastric permeability, and alter the microbiome to favor food allergy development. In a recent pediatric case-control study, use of acid suppressants in infancy was by far the single strongest risk factor identified for later development of EoE. It remains unclear which, if any, of the above factors underlies the rising frequency of EoE. These factors need not be mutually exclusive, and the cause of EoE may well be multifactorial.

Meat allergy and allergens

IgE-mediated hypersensitivity to ingested animal products, including both mammalian and avian sources, is increasingly appreciated as an important form of food allergy. Traditionally described largely in children, it is now clear that allergy to meat (and animal viscera) impacts both children and adults and represents a heterogeneous group of allergic disorders with multiple distinct syndromes. The recognition of entities such as pork-cat syndrome and delayed anaphylaxis to red meat, i.e- the α-Gal syndrome, have shed light on fundamental, and in some cases newly appreciated, features of allergic disease. These include insights into routes of exposure and mechanisms of sensitization, as well as the realization that IgE-mediated reactions can be delayed by several hours. Here we review mammalian and avian meat allergy with an emphasis on the molecular allergens and pathways that contribute to disease, as well as the role of in vitro IgE testing in diagnosis and management.

Nanoemulsion adjuvant-driven redirection of TH2 immunity inhibits allergic reactions in murine models of peanut allergy

BACKGROUND

Immunotherapy for food allergies involves progressive increased exposures to food that result in desensitization to food allergens in some subjects but not tolerance to the food. Therefore new approaches to suppress allergic immunity to food are necessary. Previously, we demonstrated that intranasal immunization with a nanoemulsion (NE) adjuvant induces robust mucosal antibody and T_H17-polarized immunity, as well as systemic T_H1-biased cellular immunity with suppression of pre-existing T_H2-biased immunity.

OBJECTIVE

We hypothesized that immunization with food in conjunction with the nanoemulsion adjuvant could lead to modulation of allergic reactions in food allergy by altering pre-existing allergic immunity and enhancing mucosal immunity.

METHODS

Mice were sensitized to peanut with aluminum hydroxide or cholera toxin. The animals were then administered 3 monthly intranasal immunizations with peanut in the nanoemulsion adjuvant or saline. Mice were then challenged with peanut to examine allergen reactivity.

RESULTS

The NE intranasal immunizations resulted in marked decreases in T_H2 cytokine, IgG₁, and IgE levels, whereas T_H1 and mucosal T_H17 immune responses were increased. After allergen challenge, these mice showed significant reductions in allergic hypersensitivity. Additionally, the NE immunizations significantly increased antigen-specific IL-10 production and regulatory T-cell counts, and the protection induced by NE was dependent in part on IL-10. Control animals immunized with intranasal peanut in saline had no modulation of their allergic response.

CONCLUSIONS

NE adjuvant-mediated induction of mucosal T_H17 and systemic T_H1-biased immunity can suppress T_H2-mediated allergy through multiple mechanisms and protect against anaphylaxis. These results suggest the potential therapeutic utility of this approach in the setting of food allergy.

Distinguishing allergens from non-allergenic homologues using Physical-Chemical Property (PCP) motifs

Quantitative guidelines to distinguish allergenic proteins from related, but non-allergenic ones are urgently needed for regulatory agencies, biotech companies and physicians. In a previous study, we found that allergenic proteins populate a relatively small number of protein families, as characterized by the Pfam database. However, these families also contain non-allergenic proteins, meaning that allergenic determinants must lie within more discrete regions of the sequence. Thus, new methods are needed to discriminate allergenic proteins within those families. Physical-Chemical Properties (PCP)-motifs specific for allergens within a Pfam class were determined for 17 highly populated protein domains. A novel scoring method based on PCP-motifs that characterize known allergenic proteins within these families was developed, and validated for those domains. The motif scores distinguished sequences of allergens from a large selection of 80,000 randomly selected non-allergenic sequences. The motif scores for the birch pollen allergen (Bet v 1) family, which also contains related fruit and nut allergens, correlated better than global sequence similarities with clinically observed cross-reactivities among those allergens. Further, we demonstrated that the average scores of allergen specific motifs for allergenic profilins are significantly different from the scores of non-allergenic profilins. Several of the selective motifs coincide with experimentally determined IgE epitopes of allergenic profilins. The motifs also discriminated allergenic pectate lyases, including Jun a 1 from mountain cedar pollen, from similar proteins in the human microbiome, which can be assumed to be non-allergens. The latter lacked key motifs characteristic of the known allergens, some of which correlate with known IgE binding sites.

Microcrystalline Tyrosine and Aluminum as Adjuvants in Allergen-Specific Immunotherapy Protect from IgE-Mediated Reactivity in Mouse Models and Act Independently of Inflammasome and TLR Signaling

Allergen immunotherapy (AIT) is the only modality that can modify immune responses to allergen exposure, but therapeutic coverage is low. One strategy to improve AIT safety and efficacy is the use of new or improved adjuvants. This study investigates immune responses produced by microcrystalline tyrosine (MCT)–based vaccines as compared with conventional aluminum hydroxide (alum). Wild-type, immune-signaling–deficient, and TCR-transgenic mice were treated with different Ags (e.g., OVA and cat dander Fel d 1), plus MCT or alum as depot adjuvants. Specific Ab responses in serum were measured by ELISA, whereas cytokine secretion was measured both in culture supernatants by ELISA or by flow cytometry of spleen cells. Upon initiation of AIT in allergic mice, body temperature and further clinical signs were used as indicators for anaphylaxis. Overall, MCT and alum induced comparable B and T cell responses, which were independent of TLR signaling. Alum induced stronger IgE and IL-4 secretion than MCT. MCT and alum induced caspase-dependent IL-1β secretion in human monocytes in vitro, but inflammasome activation had no functional effect on inflammatory and Ab responses measured in vivo. In sensitized mice, AIT with MCT-adjuvanted allergens caused fewer anaphylactic reactions compared with alum-adjuvanted allergens. As depot adjuvants, MCT and alum are comparably effective in strength and mechanism of Ag-specific IgG induction and induction of T cell responses. The biocompatible and biodegradable MCT seems therefore a suitable alternative adjuvant to alum-based vaccines and AIT.

Time to abandon the hygiene hypothesis: new perspectives on allergic disease, the human microbiome, infectious disease prevention and the role of targeted hygiene

Aims:

To review the burden of allergic and infectious diseases and the evidence for a link to microbial exposure, the human microbiome and immune system, and to assess whether we could develop lifestyles which reconnect us with exposures which could reduce the risk of allergic disease while also protecting against infectious disease.

Methods:

Using methodology based on the Delphi technique, six experts in infectious and allergic disease were surveyed to allow for elicitation of group judgement and consensus view on issues pertinent to the aim.

Results:

Key themes emerged where evidence shows that interaction with microbes that inhabit the natural environment and human microbiome plays an essential role in immune regulation. Changes in lifestyle and environmental exposure, rapid urbanisation, altered diet and antibiotic use have had profound effects on the human microbiome, leading to failure of immunotolerance and increased risk of allergic disease. Although evidence supports the concept of immune regulation driven by microbe–host interactions, the term ‘hygiene hypothesis’ is a misleading misnomer. There is no good evidence that hygiene, as the public understands, is responsible for the clinically relevant changes to microbial exposures.

Conclusion:

Evidence suggests a combination of strategies, including natural childbirth, breast feeding, increased social exposure through sport, other outdoor activities, less time spent indoors, diet and appropriate antibiotic use, may help restore the microbiome and perhaps reduce risks of allergic disease. Preventive efforts must focus on early life. The term ‘hygiene hypothesis’ must be abandoned. Promotion of a risk assessment approach (targeted hygiene) provides a framework for maximising protection against pathogen exposure while allowing spread of essential microbes between family members. To build on these findings, we must change public, public health and professional perceptions about the microbiome and about hygiene. We need to restore public understanding of hygiene as a means to prevent infectious disease.