The atopic march: Critical evidence and clinical relevance

Association between hypertensive disorders of pregnancy and the risk of asthma, eczema and allergies in offspring: A systematic review and meta-analysis

OBJECTIVE

Conduct a systematic review and meta-analysis examining the association between hypertensive disorders of pregnancy (HDP) and risk of asthma, eczema, food allergies and allergic rhinitis in the offspring.

DESIGN

A systematic review and random-effects meta-analyses were used to synthesize the published literature. PRISMA guidelines were followed throughout. Two independent reviewers carried out data extraction and quality assessment of included studies. Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess certainty of findings.

DATA SOURCES

A systematic search of PubMed, Embase, Web of Science and CINAHL was performed from inception of databases-21 April 2020, supplemented by hand-searching reference lists of included articles.

ELIGIBILITY CRITERIA

Two reviewers independently reviewed titles, abstracts and full-text articles. English language, cohort, case-control and cross-sectional published studies examining the association between HDP (primary exposure: pre-eclampsia; secondary exposures: all other HDP) and asthma, eczema, food allergies and allergic rhinitis were included.

RESULTS

Of the 2833 studies retrieved, 14 studies met inclusion criteria. Of these, 11 studies reported evidence of association between HDP and atopic disorders. Thirteen studies reported estimates for asthma. Seven of these included adjusted estimates (including 3 645 773 participants) for a pre-eclampsia-asthma relationship resulting in a pooled odds ratio (OR) of 1.14 (95% CI: 1.04, 1.26) (I²  = 62%). However, this OR was reduced to 1.08 (95% CI: (0.78, 1.48) when the large registry-based cohort studies were excluded, and only studies using parent-reported measures to determine a diagnosis of asthma were included. Four studies included adjusted estimates (including 254 998 participants) for other HDP and asthma (pooled OR: 1.02, 95% CI: 0.96, 1.09) (I²  = 0%). Two studies provided adjusted estimates (including 1 699 663 participants) for a pre-eclampsia-eczema relationship (pooled OR: 1.06, 95% CI: 0.98, 1.14) (I²  = 0%). One study including pre-eclampsia-food allergies was identified (OR: 1.28, 95% CI: 1.11, 1.46). Three studies examined a HDP (including pre-eclampsia) and allergic rhinitis relationship, with effect estimates ranging from 1.14 to 2.10. Studies were classified as low or low-moderate risk of bias, while GRADE certainty of findings were low to very low.

CONCLUSIONS

While pre-eclampsia was associated with a possible increased risk of asthma in offspring, there was no evidence for a relationship between other HDP and asthma. There is a lack of published literature examining the association between HDP and eczema, food allergy and allergic rhinitis. Further primary research is warranted to gain a better understanding of the association between HDP and the risk of childhood atopic disease.

SYSTEMATIC REVIEW REGISTRATION

Review protocol in appendix.

Atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease, clinically characterized by recurrent eczematous lesions and intense itching, leading to excoriations and susceptibility to cutaneous infections. Although it is considered a pediatric disorder, mainly starting in infancy, it is also very common in adults. Etiology of AD is complex and multifactorial: interaction between genetic susceptibility and environment, but also cutaneous barrier impairment, change in microbiome composition and innate and adaptive immune dysregulation are the main factors involved in the pathogenesis of the disease. Originally, the disorder was considered mediated by an imbalance towards a T-helper 2 response and excessive IgE production to allergens, but now it is recognized as a lifelong disposition with variable clinical expressivity, where dysfunctions of the epidermal barrier, immune system and microbiome play a central role. AD leads to a substantial psycho-social burden on patients and their relatives and increases the risk of other allergic and non allergic disorders. The real economic impact of AD is difficult to measure due to the broad spectrum of disease severity and the multiple direct and indirect costs, but the overall medical expenses seem to be very high and similar to those of other diseases such as diabetes. Currently, a multiple therapeutic approach is aimed only at improving the skin state, reducing itching and keeping a stable condition. New safety and curative treatments may be developed only after enhancing our understanding on the pathogenesis of AD and the heterogeneity of its clinical manifestations. (www.actabiomedica.it)

Early life microbial exposures and allergy risks: opportunities for prevention

Allergies, including asthma, food allergy and atopic dermatitis, are increasing in prevalence, particularly in westernized countries. Although a detailed mechanistic explanation for this increase is lacking, recent evidence indicates that, in addition to genetic predisposition, lifestyle changes owing to modernization have an important role. Such changes include increased rates of birth by caesarean delivery, increased early use of antibiotics, a westernized diet and the associated development of obesity, and changes in indoor and outdoor lifestyle and activity patterns. Most of these factors directly and indirectly impact the formation of a diverse microbiota, which includes bacterial, viral and fungal components; the microbiota has a leading role in shaping (early) immune responses. This default programme is markedly disturbed under the influence of environmental and lifestyle risk factors. Here, we review the most important allergy risk factors associated with changes in our exposure to the microbial world and the application of this knowledge to allergy prevention strategies.

IgE Autoreactivity in Atopic Dermatitis: Paving the Road for Autoimmune Diseases?

Atopic dermatitis (AD) is a common skin disease affecting 20% of the population beginning usually before one year of age. It is associated with the emergence of allergen-specific IgE, but also with autoreactive IgE, whose function remain elusive. This review discusses current knowledge relevant to the mechanisms, which leads to the secretion of autoreactive IgE and to the potential function of these antibodies in AD. Multiple autoantigens have been described to elicit an IgE-dependent response in this context. This IgE autoimmunity starts in infancy and is associated with disease severity. Furthermore, the overall prevalence of autoreactive IgE to multiple auto-antigens is high in AD patients. IgE-antigen complexes can promote a facilitated antigen presentation, a skewing of the adaptive response toward type 2 immunity, and a chronic skin barrier dysfunction and inflammation in patients or AD models. In AD, skin barrier defects and the atopic immune environment facilitate allergen sensitization and the development of other IgE-mediated allergic diseases in a process called the atopic march. AD is also associated epidemiologically with several autoimmune diseases showing autoreactive IgE secretion. Thus, a potential outcome of IgE autoreactivity in AD could be the development of further autoimmune diseases.

Epicutaneous sensitization in the development of food allergy: What is the evidence and how can this be prevented?

There is increasing evidence regarding the importance of allergic sensitization through the skin. In this review, we provide an overview of the atopic march and immune mechanism underlying the sensitization and effector phase of food allergy. We present experimental models and human data that support the concept of epicutaneous sensitization and how this forms one half of the dual-allergen exposure hypothesis. We discuss specific important elements in the skin (FLG and other skin barrier gene mutations, Langerhans cells, type 2 innate lymphoid cells, IL-33, TSLP) that have important roles in the development of allergic responses as well as the body of evidence on environmental allergen exposure and how this can sensitize an individual. Given the link between skin barrier impairment, atopic dermatitis, food allergy, allergic asthma, and allergic rhinitis, it is logical that restoring the skin barrier and prevention or treating atopic dermatitis would have beneficial effects on prevention of related allergic diseases, particularly food allergy. We present the experimental and human studies that have evaluated this approach and discuss various factors which may influence the success of these approaches, such as the type of emollient chosen for the intervention, the role of managing skin inflammation, and differences between primary and secondary prevention of atopic dermatitis to achieve the desired outcome.

Food allergy and atopic dermatitis

Atopic dermatitis (AD), characterized by intense pruritus, eczematous lesions, and a relapsing disease course, is a chronic inflammatory skin disease that affects both children and adults. AD often begins in infancy and is associated with atopic diseases in the personal or family history.1 Environmental factors may trigger AD by affecting the skin barrier and by triggering inflammation. The elicitation of T-helper type 2 cytokines further impairs the epidermal barrier and leads to the penetration of irritants and allergens into the epidermis and thereby perpetuating inflammation. The presence of AD and its severity has been shown to positively correlate with risk of developing food allergy (FA). Children with AD are estimated to be six times more likely to develop FA compared with their healthy peers. It has been reported that nearly 40% of children with moderate-to-severe AD have immunoglobulin E (IgE) mediated FA compared with only 6% in the general population. Although analysis of experimental data has linked skin inflammation in AD to FA, with food challenges reproducing symptoms and avoidance diets improving AD, elimination diets are not known to cure AD and may have unfavorable consequences, such as loss of tolerance, which leads to immediate-type allergy, including anaphylaxis, nutritional deficiencies, growth failure, and reduction of quality of life for the patient and family. Exacerbation of AD can be inaccurately attributed to foods. Individuals with AD are often sensitized to foods with positive testing results, however, able to tolerate the food. In light of widespread ordering and commercial availability of serum specific IgE for FA, testing for FA is recommended only if, from a detailed clinical history, immediate-type allergic symptoms occur with ingestion of food, or in infants with AD who do not improve with optimal skin care.

Food allergy and asthma

Food allergies (FA) and asthma commonly coexist in patients, with asthma affecting 14% of school-age children and with FA affecting up to 8% of children in the United States. Compared with children without FA, children with FA are two to four times more likely to have asthma. The timings of food sensitization and FA seem to be strong predictors of asthma onset in childhood; results of studies show that food sensitization in the first few years of life is associated with increased odds of developing early wheeze. Having multiple FAs as opposed to a single FA further compounds the risk of asthma. Reciprocally, there is a strong association between the presence of food sensitization and/or FA and poor asthma control, including increased asthma-related healthcare utilization and emergency medication use. Asthma is a risk factor in ~75% of fatal food-related anaphylaxis cases. Therefore, besides FA education and management, patients with FA and with asthma should optimize medical therapy of their asthma and receive asthma education, including identifying possible asthma triggers. Furthermore, allergists should ensure that asthma must be well controlled before conducting oral food challenges. Timely administration of epinephrine is lifesaving and remains the firstline treatment during food-induced anaphylaxis, especially in patients with asthma. Among those biologic therapies that have been highly effective in treating asthma, omalizumab and dupilumab are now also being studied as treatments for FA.

Research Progress in Atopic March

The incidence of allergic diseases continues to rise. Cross-sectional and longitudinal studies have indicated that allergic diseases occur in a time-based order: from atopic dermatitis and food allergy in infancy to gradual development into allergic asthma and allergic rhinitis in childhood. This phenomenon is defined as the "atopic march". Some scholars have suggested that the atopic march does not progress completely in a temporal pattern with genetic and environmental factors. Also, the mechanisms underlying the atopic march are incompletely understood. Nevertheless, the concept of the atopic march provides a new perspective for the mechanistic research, prediction, prevention, and treatment of atopic diseases. Here, we review the epidemiology, related diseases, mechanistic studies, and treatment strategies for the atopic march.

Unsupervised modeling and genome-wide association identify novel features of allergic march trajectories

BACKGROUND

The allergic march refers to the natural history of allergic conditions during infancy and childhood. However, population-level disease incidence patterns do not necessarily reflect the development of allergic disease in individuals. A better understanding of the factors that predispose to different allergic trajectories is needed.

OBJECTIVE

Our aim was to determine the demographic and genetic features that are associated with the major allergic march trajectories.

METHODS

Presence or absence of common allergic conditions (atopic dermatitis [AD], IgE-mediated food allergy [IgE-FA], asthma, and allergic rhinitis [AR]) was ascertained in a pediatric primary care birth cohort of 158,510 subjects. Hierarchic clustering and decision tree modeling were used to associate demographic features with allergic outcomes. Genome-wide association study was used to test for risk loci associated with specific allergic trajectories.

RESULTS

We found an association between self-identified black race and progression from AD to asthma. Conversely, Asian or Pacific Islander race was associated with progression from AD to IgE-mediated food allergy, and white race was associated with progression from AD to AR. Genome-wide association study of trajectory groups identified risk loci associated with progression from AD to asthma (rs60242841) and from AD to AR (rs9565267, rs151041509, and rs78171803). Consistent with our epidemiologic associations, rs60242841 was more common in individuals of African ancestry than in individuals of European ancestry, whereas rs9565267 and rs151041509 were more common in individuals of European ancestry than in individuals of African ancestry.

CONCLUSION

We have identified novel associations between race and progression along distinct allergic trajectories. Ancestral genetic differences may contribute to these associations. These results uncover important health disparities, refine the concept of the allergic march, and represent a step toward developing individualized medical approaches for these conditions.

High Frequency of Concomitant Food Allergy Development and Autoantibody Formation in Children Who Have Undergone Liver Transplantation

BACKGROUND

Allergy and other immune-mediated diseases are more frequently reported in children who have undergone liver transplantation. Furthermore, autoantibodies are also prevalent, suggesting a state of immune dysregulation in these patients. Whether or not these processes occur simultaneously in the same individual has not been studied previously.

METHODS

A cohort of 43 children who had undergone liver transplantation for nonautoimmune liver disease at median age of 1.3 years was investigated for allergy and autoimmune disease. Sensitization to food and inhalant allergens was assessed, and autoantibodies were measured.

RESULTS

The prevalence of food allergy was 26% and that of respiratory allergy was 23%, whereas 33% and 26% of the subjects were sensitized to food and inhalant allergens, respectively. Autoimmune disease (ie, autoimmune hepatitis) occurred in a single individual (2%), whereas autoantibodies were present in 44% of the children. Food allergy and autoantibodies occurred concomitantly in 19% of the children, which was almost twice the frequency expected by chance (11%, P = 0.04). Respiratory allergy and the presence of autoantibodies were unrelated (12% concurrence versus the expected 10%, P = 0.73). In the logistic regression analysis, autoantibody formation was associated with discontinued immunosuppression and food allergy, with odds ratios of 13 (P = 0.01) and 7.1 (P = 0.03), respectively.

CONCLUSIONS

In contrast to respiratory allergy, food allergy and autoantibody formation occurred together in the same children who underwent liver transplantation at a frequency higher than would be expected by chance. This may reflect an underlying immune dysregulation that impairs immune tolerance to both food allergens and autoantigens.

Molar-Incisor Hypomineralisation and Allergic March

Background

Molar-incisor hypomineralisation is a disturbance in dental development that involves first permanent molars as well as permanent incisors with a prevalence that ranges from 2.5% to 40%.

Aim

The objective of this study was to investigate the effect of atopic diseases on the development of molar-incisor hypomineralisation.

Material and methods

The study was based on the review of the medical records of a group of 102 children whose age was between eight and 12 years and 11 months and who had previously been diagnosed with MIH.

Results

An association (χ², p≤0.05) has been found between molar-incisor hypomineralisation in children's mouths and the existence of: atopic dermatitis (OR=2.504; 1.54-4.05 CI 95%), food allergies (OR=2.171; 1.03-4.56 CI 95%), allergic rhinitis (OR=0.17; 0.02-1.27 CI 95%), and asthmatic bronchitis/asthma (OR=1.707; 1.05-2.76 CI 95%). When analyzing the pathologies by location, we found that atopic dermatitis, food allergies, allergic rhinitis and asthma were more frequent in children who had (p≤0.05) #12, #11, #21, #22, #36, #31, #41 and #42 affected.

Conclusions

The association between molar-incisor hypomineralisation and the presence of atopic diseases in the first 36 months of life underlines the convenience of approaching this problem from a multidisciplinary perspective.

Resolving Clinical Phenotypes into Endotypes in Allergy: Molecular and Omics Approaches

Allergic diseases are highly complex with respect to pathogenesis, inflammation, and response to treatment. Current efforts for allergic disease diagnosis have focused on clinical evidence as a binary outcome. Although outcome status based on clinical phenotypes (observable characteristics) is convenient and inexpensive to measure in large studies, it does not adequately provide insight into the complex molecular determinants of allergic disease. Individuals with similar clinical diagnoses do not necessarily have similar disease etiologies, natural histories, or responses to treatment. This heterogeneity contributes to the ineffective response to treatment leading to an annual estimated cost of $350 billion in the USA alone. There has been a recent focus to deconvolute the clinical heterogeneity of allergic diseases into specific endotypes using molecular and omics approaches. Endotypes are a means to classify patients based on the underlying pathophysiological mechanisms involving distinct functions or treatment response. The advent of high-throughput molecular omics, immunophenotyping, and bioinformatics methods including machine learning algorithms is facilitating the development of endotype-based diagnosis. As we move to the next decade, we should truly start treating clinical endotypes not clinical phenotype. This review highlights current efforts taking place to improve allergic disease endotyping via molecular omics profiling, immunophenotyping, and machine learning approaches in the context of precision diagnostics in allergic diseases. Graphical Abstract.

EAACI Allergen Immunotherapy User's Guide

Allergen immunotherapy is a cornerstone in the treatment of allergic children. The clinical efficiency relies on a well-defined immunologic mechanism promoting regulatory T cells and downplaying the immune response induced by allergens. Clinical indications have been well documented for respiratory allergy in the presence of rhinitis and/or allergic asthma, to pollens and dust mites. Patients who have had an anaphylactic reaction to hymenoptera venom are also good candidates for allergen immunotherapy. Administration of allergen is currently mostly either by subcutaneous injections or by sublingual administration. Both methods have been extensively studied and have pros and cons. Specifically in children, the choice of the method of administration according to the patient's profile is important. Although allergen immunotherapy is widely used, there is a need for improvement. More particularly, biomarkers for prediction of the success of the treatments are needed. The strength and efficiency of the immune response may also be boosted by the use of better adjuvants. Finally, novel formulations might be more efficient and might improve the patient's adherence to the treatment. This user's guide reviews current knowledge and aims to provide clinical guidance to healthcare professionals taking care of children undergoing allergen immunotherapy.

Skin emollient and early complementary feeding to prevent infant atopic dermatitis (PreventADALL): a factorial, multicentre, cluster-randomised trial

BACKGROUND

Skin emollients applied during early infancy could prevent atopic dermatitis, and early complementary food introduction might reduce food allergy in high-risk infants. The study aimed to determine if either regular skin emollients applied from 2 weeks of age, or early complementary feeding introduced between 12 and 16 weeks of age, reduced development of atopic dermatitis by age 12 months in the general infant population.

METHODS

This population-based 2×2 factorial, randomised clinical trial was done at Oslo University Hospital and Østfold Hospital Trust, Oslo, Norway; and Karolinska University Hospital, Stockholm, Sweden. Infants of women recruited antenatally at the routine ultrasound pregnancy screening at 18 weeks were cluster-randomised at birth from 2015 to 2017 to the following groups: (1) controls with no specific advice on skin care while advised to follow national guidelines on infant nutrition (no intervention group); (2) skin emollients (bath additives and facial cream; skin intervention group); (3) early complementary feeding of peanut, cow's milk, wheat, and egg (food intervention group); or (4) combined skin and food interventions (combined intervention group). Participants were randomly assigned (1:1:1:1) using computer- generated cluster randomisation based on 92 geographical living area blocks as well as eight 3-month time blocks. Carers were instructed to apply the interventions on at least 4 days per week. Atopic dermatitis by age 12 months was the primary outcome, based on clinical investigations at 3, 6 and 12 months by investigators masked to group allocation. Atopic dermatitis was assessed after completing the 12-month investigations and diagnosed if either of the UK Working Party and Hanifin and Rajka (12 months only) diagnostic criteria were fulfilled. The primary efficacy analyses was done by intention-to-treat analysis on all randomly assigned participants. Food allergy results will be reported once all investigations at age 3 years are completed in 2020. This was a study performed within ORAACLE (the Oslo Research Group of Asthma and Allergy in Childhood; the Lung and Environment). The study is registered at clinicaltrials.gov, NCT02449850.

FINDINGS

2697 women were recruited between Dec 9, 2014, and Oct 31, 2016, from whom 2397 newborn infants were enrolled from April 14, 2015, to April 11, 2017. Atopic dermatitis was observed in 48 (8%) of 596 infants in the no intervention group, 64 (11%) of 575 in the skin intervention group, 58 (9%) of 642 in the food intervention group, and 31 (5%) of 583 in the combined intervention group. Neither skin emollients nor early complementary feeding reduced development of atopic dermatitis, with a risk difference of 3·1% (95% CI -0·3 to 6·5) for skin intervention and 1·0% (-2·1 to 4·1) for food intervention, in favour of control. No safety concerns with the interventions were identified. Reported skin symptoms and signs (including itching, oedema, exanthema, dry skin, and urticaria) were no more frequent in the skin, food, and combined intervention groups than in the no intervention group.

INTERPRETATION

Neither early skin emollients nor early complementary feeding reduced development of atopic dermatitis by age 12 months. Our study does not support the use of these interventions to prevent atopic dermatitis by 12 months of age in infants.

FUNDING

The study was funded by several public and private funding bodies: The Regional Health Board South East, The Norwegian Research Council, Health and Rehabilitation Norway, The Foundation for Healthcare and Allergy Research in Sweden-Vårdalstiftelsen, Swedish Asthma and Allergy Association's Research Foundation, Swedish Research Council-the Initiative for Clinical Therapy Research, The Swedish Heart-Lung Foundation, SFO-V at the Karolinska Institute, Freemason Child House Foundation in Stockholm, Swedish Research Council for Health, Working Life and Welfare-FORTE, Oslo University Hospital, the University of Oslo, and Østfold Hospital Trust.

Daily emollient during infancy for prevention of eczema: the BEEP randomised controlled trial

BACKGROUND

Skin barrier dysfunction precedes eczema development. We tested whether daily use of emollient in the first year could prevent eczema in high-risk children.

METHODS

We did a multicentre, pragmatic, parallel-group, randomised controlled trial in 12 hospitals and four primary care sites across the UK. Families were approached via antenatal or postnatal services for recruitment of term infants (at least 37 weeks' gestation) at high risk of developing eczema (ie, at least one first-degree relative with parent-reported eczema, allergic rhinitis, or asthma, diagnosed by a doctor). Term newborns with a family history of atopic disease were randomly assigned (1:1) to application of emollient daily (either Diprobase cream or DoubleBase gel) for the first year plus standard skin-care advice (emollient group) or standard skin-care advice only (control group). The randomisation schedule was created using computer-generated code (stratified by recruiting centre and number of first-degree relatives with atopic disease) and participants were assigned to groups using an internet-based randomisation system. The primary outcome was eczema at age 2 years (defined by UK working party criteria) with analysis as randomised regardless of adherence to allocation for participants with outcome data collected, and adjusting for stratification variables. This trial is registered with ISRCTN, ISRCTN21528841. Data collection for long-term follow-up is ongoing, but the trial is closed to recruitment.

FINDINGS

1394 newborns were randomly assigned to study groups between Nov 19, 2014, and Nov 18, 2016; 693 were assigned to the emollient group and 701 to the control group. Adherence in the emollient group was 88% (466 of 532) at 3 months, 82% (427 of 519) at 6 months, and 74% (375 of 506) at 12 months in those with complete questionnaire data. At age 2 years, eczema was present in 139 (23%) of 598 infants with outcome data collected in the emollient group and 150 (25%) of 612 infants in the control group (adjusted relative risk 0·95 [95% CI 0·78 to 1·16], p=0·61; adjusted risk difference -1·2% [-5·9 to 3·6]). Other eczema definitions supported the results of the primary analysis. Mean number of skin infections per child in year 1 was 0·23 (SD 0·68) in the emollient group versus 0·15 (0·46) in the control group; adjusted incidence rate ratio 1·55 (95% CI 1·15 to 2·09).

INTERPRETATION

We found no evidence that daily emollient during the first year of life prevents eczema in high-risk children and some evidence to suggest an increased risk of skin infections. Our study shows that families with eczema, asthma, or allergic rhinitis should not use daily emollients to try and prevent eczema in their newborn.

FUNDING

National Institute for Health Research Health Technology Assessment.

Asthma predictive index as a useful diagnostic tool in preschool children: a cross-sectional study in Korea

BACKGROUND

It is challenging to diagnose asthma in preschool children. The asthma predictive index (API) has been used to predict asthma and decide whether to initiate treatment in preschool children.

PURPOSE

This study aimed to investigate the association between questionnaire-based current asthma with API, pulmonary function, airway hyperreactivity (AHR), fractional expiratory nitric oxide (FeNO), and atopic sensitization in preschool children.

METHODS

We performed a population-based cross-sectional study in 916 preschool children aged 4-6 years. We defined current asthma as the presence of both physician-diagnosed asthma and at least one wheezing episode within the previous 12 months using a modified International Study of Asthma and Allergies in Childhood questionnaire. Clinical and laboratory parameters were compared between groups according to the presence of current asthma.

RESULTS

The prevalence of current asthma was 3.9% in the study population. Children with current asthma showed a higher rate of positive bronchodilator response and loose and stringent API scores than children without current asthma. The stringent API was associated with current asthma with 72.2% sensitivity and 82.0% specificity. The diagnostic accuracy of the stringent API for current asthma was 0.771. However, no intergroup differences in spirometry results, methacholine provocation test results, FeNO level, or atopic sensitization rate were observed.

CONCLUSION

The questionnaire-based diagnosis of current asthma is associated with API, but not with spirometry, AHR, FeNO, or atopic sensitization in preschool children.

Eczema phenotypes and risk of allergic and respiratory conditions in school age children

Background

Eczema phenotypes based on eczema onset and persistence might better identify groups prone to allergic and respiratory conditions than a binary definition of eczema. We examined the associations of childhood eczema phenotypes with allergic sensitization, allergy, asthma and lung function at school age.

Methods

This study among 4277 children was embedded in a multi-ethnic population-based prospective cohort study. Five eczema phenotypes (never, early transient, mid-transient, late transient, persistent) based on parental-reported physician-diagnosed eczema from age 6 months until 10 years were identified. At age 10 years, allergic sensitization was measured by skin prick tests, physician-diagnosed allergy and asthma by parent-reported questionnaires, and lung function by spirometry. Adjusted linear, logistic and multinomial regression models were applied.

Results

Compared with never eczema, all eczema phenotypes were associated with increased risks of asthma (odds ratios (OR) range (95% confidence interval): 2.68 (1.58, 4.57) to 11.53 (6.65, 20.01)), food and inhalant allergic sensitization (1.72 (1.25, 2.36) to 12.64 (7.20, 22.18)), and physician-diagnosed inhalant allergy (1.92 (1.34, 2.74) to 11.91 (7.52, 18.86)). Strongest effect estimates were observed of early and persistent eczema with the risk of physician-diagnosed food allergy (OR 6.95 (3.76, 12.84) and 35.05 (18.33, 70.00), respectively) and combined asthma and physician-diagnosed allergy (7.11 (4.33, 11.67) and 29.03 (15.27, 55.22), respectively). Eczema phenotypes were not associated with lung function measures.

Conclusion

Eczema phenotypes were differentially associated with risks of respiratory and allergic conditions in school-aged children. Children with early transient and persistent eczema might benefit from more intense follow-up for early identification and treatment of asthma and allergies.

Measuring Microbiome Effectiveness: A Role for Ingestible Sensors

Across the world there is an increasingly heavy burden of noncommunicable diseases related to obesity, mental health, and atopic disease. In a previous publication, we followed the developing idea that that these conditions arise as our microbiome loses diversity, but there seems to be no generally applicable way to assess the significance of this loss. Our work revisited the findings of the African studies by Denis Burkitt who reported that the frequency of what he called Western diseases were inversely proportional to the average faecal volumes of affected populations. Although he ascribed this to fibre in the diet, it now seems more likely that the drop in faecal volume with the onset of disease is due to the loss of a fully functioning microbiome. We suggested that the microbiome could be considered to be a single mutualistic microbial community interacting with our body by two complementary sets of semiochemicals, i.e., allomones to feed the microbiota by facilitating the efficient transfer of nutrition through the gut and kairomones to calibrate our immune system by an as yet unknown mechanism. The bioactive compounds, dopamine and serotonin, are known to be present in the gut lumen under the influence of intestinal microbiota and we suggest that these are part of this allomone-like system. In light of this possibility, it is of critical importance to develop a method of quantifying the microbiome effectiveness. Ingestible sensors consist of a miniaturized detector and transmitter packed into a capsule that is swallowed and tracked through the intestine. The aim of this article is to explore the possible development of such ingestible detectors for these or other compounds that can act as a surrogate marker for microbiome effectiveness. We consider that the ability to provide real-time quantitative information on the interaction of the microbiome with different nutrients promises to be a valuable new tool to unravel the mystery of these noncommunicable illnesses, i.e., microbiome-function deficiency diseases.

Role of Galectin-9 in Atopic Dermatitis - Is It Mediated Through E Selectin? A Clinical and Immunohistochemical Study

Background

Atopic dermatitis (AD) is a recognized T helper (Th)2, allergic, skin disease. Galectin-9 (gal-9) is a member of galectin family. It alters T-cell balance resulting in Th2 polarization. These Th2 cells yield various cytokines that may influence E selectin expression. Therefore, we hypothesized that gal-9 may have an active role in AD and this role could be mediated through E selectin.

Objective

To assess this hypothesis, immunohistochemical expression of gal-9 and E selectin was investigated in skin lesions, from atopic dermatitis patients, and compared.

Methods

Twenty-two atopic dermatitis patients and ten controls were included in this case-control study. SCORAD score was used to evaluate atopic dermatitis severity. Biopsies from skin lesions of AD patients and matched sites of controls were taken and stained immunohistochemically by gal-9 and E selectin polyclonal antibodies.

Results

Compared to controls, atopic dermatitis patients exhibited a significant increased gal-9 H score, percent of expression, cellular localization (P˂0.001) and intensity (P=0.04) as well as dermal cellular infiltrate (P˂0.001). Also, there were significant elevations in E selectin H score (P=0.002), percent of expression (P=0.001) and cellular localization (P<0.001) as well as dermal inflammatory infiltrates in AD cases than controls. In AD, 20 cases showed co expression of both gal-9 and E selectin in the epidermis with insignificant correlation between their H scores.

Study Limitations

This study only included a small number of studied subjects.

Conclusion

Galectin-9 and E selectin participates independently in atopic dermatitis pathogenesis, that may help in development of new therapeutic agents in atopic dermatitis management program.

Potential of phytochemicals as immune-regulatory compounds in atopic diseases: A review

Atopic diseases (atopic dermatitis, asthma and allergic rhinitis) affects a huge number of people around the world and their incidence rate is on rise. Atopic dermatitis (AD) is more prevalent in paediatric population which sensitizes an individual to develop allergic rhinitis and asthma later in life. The complex pathogenesis of these allergic diseases though involves numerous cellular signalling pathways but redox imbalance has been reported to be critical for induction/perpetuation of inflammatory process under such conditions. The realm of complementary and alternative medicine has gained greater attention because of the reported anti-oxidant/anti-inflammatory properties. Several case studies of treating atopic diseases with homeopathic remedies have provided positive results. Likewise, pre-clinical studies suggest that various natural compounds suppress allergic response via exhibiting their anti-oxidant potential. Despite the reported beneficial effects of phytochemicals in experimental model system, the clinical success has not been documented so far. It appears that poor absorption and bioavailability of natural compounds may be one of the reasons for realizing their full potential. The current paper throws light on impact of phytochemicals in the redox linked cellular and signalling pathways that may be critical in manifestation of atopic diseases. Further, an effort has been made to identify the gaps in the area so that future strategies could be evolved to exploit the medicinal value of various phytochemicals for an improved efficiency.

Epicutaneous sensitization to food allergens in atopic dermatitis: What do we know?

Atopic dermatitis (AD) is a chronic inflammatory skin disease mainly affecting children, which has no definitive curative therapy apart from natural outgrowing. AD is persistent in 30%-40% of children. Epithelial barrier dysfunction in AD is a significant risk factor for the development of epicutaneous food sensitization, food allergy, and other allergic disorders. There is evidence that prophylactic emollient applications from birth may be useful for primary prevention of AD, but biomarkers are needed to guide cost-effective targeted therapy for high-risk individuals. In established early-onset AD, secondary preventive strategies are needed to attenuate progression to other allergic disorders such as food allergy, asthma, and allergic rhinitis (the atopic march). This review aims to describe the mechanisms underpinning the development of epicutaneous sensitization to food allergens and progression to clinical food allergy; summarize current evidence for interventions to halt the progression from AD to food sensitization and clinical food allergy; and highlight unmet needs and directions for future research.

Targeted deletion of the TSLP receptor reveals cellular mechanisms that promote type 2 airway inflammation

Thymic stromal lymphopoietin (TSLP) is a critical upstream cytokine inducing type 2 inflammation in various diseases, including asthma and atopic dermatitis. Accumulating evidence suggests that TSLP can directly stimulate a variety of immune cells, such as dendritic cells (DCs), basophils, T cells, and group 2 innate lymphoid cells (ILC2s). However, which cell types directly respond to TSLP in vivo and how TSLP initiates type 2 inflammation has remained controversial. To define the precise role of TSLP in vivo, for the first time we generated multiple cell lineage-specific TSLP receptor-deficient mice to systematically dissect the cell-intrinsic requirements for TSLP responsiveness in type 2 inflammation in the lung. In papain-induced innate immune-mediated type 2 airway inflammation, TSLP directly stimulated ILC2s, but not basophils, leading to enhanced type 2 inflammation. On the other hand, in OVA-induced adaptive immune-mediated type 2 airway inflammation, TSLP principally acted on DCs and CD4 + T cells during the sensitization phase, but not basophils or ILC2s, and facilitated the development of Th2 cell-mediated airway inflammation. Together, these findings reveal that TSLP activates distinct immune cell cascades in the context of innate and adaptive immune-mediated type 2 inflammation.

The Risk of Developing Constipation After Neonatal Necrotizing Enterocolitis

Background: Neonatal necrotizing enterocolitis (NEC) is a complex and lethal inflammatory bowel necrosis that primarily affects premature infants. Gut dysbiosis has been implicated in the pathogenesis of NEC. We aim to assess the association between NEC and two other diseases in children, including allergic diseases and constipation, considered to be associated with the alterations in gut microbiota composition. Methods: This retrospective population-based cohort study was conducted using the Taiwan Birth Registration Database, Birth Certificate Application, and National Health Insurance Research Database to inter-link the medical claims of neonates and their mothers. A total of 2,650,634 delivery events were retrieved from 2005 to 2015. We identified a NEC cohort and selected a comparison cohort according to propensity score matching (1:1). Cox proportional hazard regression models were used to determine possible associations of predictors and to obtain adjusted hazard ratios (aHRs). Results: A total of 1,145 subjects in the NEC cohort and 1,145 subjects in the matched cohort were analyzed during the observation period. No significant difference was observed in the incidence of allergic diseases between the two groups. NEC patients had a significant 30.7% increased risk of developing constipation (aHR = 1.307; 95% CI 1.089-1.568). The cumulative incidence of constipation was significantly higher in the NEC cohort than in the matched cohort by the end of follow-up (log-rank test P = 0.003). Conclusion: Infants with NEC have a significantly higher incidence rate of developing constipation and FTT but no increased risk of allergic diseases.

The effect of an educational program for pregnant women to prevent allergic diseases in infants: study protocol for a randomized controlled trial

BACKGROUND

Allergic diseases in infants have dramatically increased in developed countries during the past few decades. To date, extensive research has been done on risk factors for allergies in infancy, and preventive measures against them. However, the effect of the primary approach to preventing infantile allergy is still limited. The aim of this trial is to evaluate whether prenatal education interventions, including the latest public research results on allergic diseases, prevent the onset of infant allergies.

METHODS/DESIGN

We designed a randomized controlled, two-arm (standard prenatal education vs our education), parallel-group, assessor-blind trial. A sample of 120 pregnant women will be recruited at Chiba Aiyu-kai Kinen Hospital and allocation is by computer-generated randomization. Pregnant women in the intervention arm participate in the childbirth education program established by the specialist and a pediatric allergy educator. The program was developed based on evidences supporting interventions on primary prevention, which are suggested to be beneficial to infantile allergies in recent studies. The primary objective of the study is to determine whether it is possible to establish effective behaviors for allergy prevention in early infancy in the children of pregnant women who participate in an educational program developed by pediatric allergy specialists. Four months after birth, their behaviors will be compared against those of pregnant women who did not participate in the program.

DISCUSSION

Allergies are common in many individuals worldwide, and can be present from babyhood through the person's lifetime. One of the strong points of this study is that it should provide pregnant women with accumulated information on preventive knowledge against allergy, that can be effective in some cases, and that women can apply a combination of these behaviors before and after pregnancy. The results of our program will be publicized to help change the behaviors of mothers, and, if the program is effective, for preventing allergies in infants, it will be disclosed worldwide as a new preventive strategy for allergy in infants.

TRIAL REGISTRATION

UMIN-CTR, ID: UMIN000034730 Retrospectively registered on 1 December 2018.

Microbial interactions in the atopic march

The human body is populated by a large number of microorganisms and exist in symbiosis with these immensely diverse communities, which are suggested to influence health and disease. The microbiota plays an essential role in the maturation and function of the immune system. The prevalence of atopic diseases has increased drastically over the past decades, and the co-occurrence of multiple allergic diseases and allergic sensitization starting in early life has gained a great deal of attention. Immune responses in different organs affected by allergic diseases (e.g. skin, intestine and lung) may be linked to microbial changes in peripheral tissues. In the current review, we provide an overview of the current understanding of microbial interactions in allergic diseases and their potential role in the atopic march.

Elevated Atopic Comorbidity in Patients with Food Protein-Induced Enterocolitis

BACKGROUND

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy. Its relationship to the major atopic manifestations (atopic dermatitis [AD], IgE-mediated food allergy [IgE-FA], allergic rhinitis [AR], asthma) is not understood.

OBJECTIVE

To determine the clinical characteristics, epidemiologic features, and natural history of FPIES in relation to the major atopic manifestations.

METHODS

We examined our primary care birth cohort of 158,510 pediatric patients, of whom 214 patients met 2017 FPIES diagnostic criteria. We measured the influence of FPIES on developing subsequent atopic disease.

RESULTS

Pediatric FPIES incidence was between 0.17% and 0.42% depending on birth year. As in prior reports, most patients had an acute presentation (78%), and milk, soy, oat, rice, potato, and egg were common triggers. The mean age of diagnosis was 6.8 months. Atopic comorbidity was higher in patients with FPIES compared with healthy children (AD, 20.6% vs 11.7%; IgE-FA, 23.8% vs 4.0%; asthma, 26.6% vs 18.4%; AR, 28.0% vs 16.7%; P < .001 χ²). However, longitudinal analyses indicated that prior FPIES did not influence the rate of atopy development.

CONCLUSIONS

The incidence of FPIES in our cohort was initially low, but is increasing. Food allergen distribution, presentation, and age of onset are similar to prior reports. Patients with FPIES have high rates of atopic comorbidity. However, longitudinal analysis does not support direct causation as the etiology of these associations. Rather it suggests a shared predisposition to both types of allergy, or associative bias effects. This work refines our understanding of the natural history of FPIES by elucidating associations between FPIES and atopy.

Approach to the Assessment and Management of Pediatric Patients with Atopic Dermatitis: A Consensus Document. Section II: Comorbid Disease in Pediatric Atopic Dermatitis

Pediatric atopic dermatitis (AD) is one of the most common skin conditions encountered by health-care providers caring for infants, children, and adolescents. Pediatric patients with AD may present with other allergic and nonallergic comorbidities that require appropriate treatment and referral. They may also experience a trajectory of allergic diseases known as the atopic march, which depends on a complex interaction between genetic and environmental factors and likely involves early epidermal barrier dysfunction. Here we provide a review and clinical recommendations on the assessment and referral of comorbidities in pediatric AD.

Disease trajectories in childhood atopic dermatitis: an update and practitioner's guide

BACKGROUND

Atopic dermatitis (AD) is a heterogeneous disease with a multifactorial aetiology and complex pathophysiology. This heterogeneity translates into different trajectories of disease progression with respect to severity, persistence and risk of development of atopic comorbidities. Determining which possible disease trajectories or comorbidities any individual child might develop is challenging in clinical practice. Tools that help identify paediatric patients at higher risk of disease progression would greatly aid clinicians.

METHODS

We reviewed recent cohort studies to synthesize and simplify the epidemiological data to try to identify shared clinically relevant characteristics that may help physicians estimate the risk of disease progression in paediatric patients with AD.

RESULTS

Despite the variability in data collection and methods of analysis and their limitations, there are common patterns of early-childhood AD that may aid in the estimation of risk for disease progression. Factors associated with risk of AD progression include younger age of onset, family history of atopy, greater AD severity, filaggrin mutations, urban environment and polysensitization and/or allergic multimorbidity. Based on these factors, we provide a practitioner's guide for identifying, counselling and/or referring infants and children with AD at potentially higher risk of developing persistent AD and atopic comorbidities. We also present clinical scenarios to illustrate how these data relate to real-life situations.

CONCLUSIONS

Useful insights are provided for physicians and patients to inform them better about the risk of AD progression and to help guide care pathways for the paediatric population with AD. What's already known about this topic? The complex pathophysiology of atopic dermatitis (AD) translates into a heterogeneous clinical presentation and trajectories of disease progression. Although the consensus is that most paediatric patients with AD will eventually 'outgrow' the disease or follow the longitudinal trajectory known as the 'atopic march', a significant proportion will develop persistent AD and/or other atopic conditions. No known factors conclusively predict the risk of progression or development of comorbidities. What does this study add? Recent analyses of data from large cohorts of paediatric patients with AD have suggested the existence of potentially discrete clusters of patients who present with relatively common AD phenotypes. These studies have shed some light onto the factors associated with risk of progression, which we review in this article. A practitioner's guide with clinical scenarios is provided to help identify patients at high risk of progression to determine whether a patient should be monitored and/or would require specialist referral.

Atopic March: Collegium Internationale Allergologicum Update 2020

In recent decades, the worldwide prevalence of allergic disease has increased considerably. The atopic march is a model aimed at explaining the apparent progression of allergic diseases from atopic dermatitis (AD) to allergic asthma (AA) and to allergic rhinitis (AR). It hypothesizes that allergic disease begins, typically in children, with the development of AD, then AA, and finally progresses to AR. This theory has been widely studied in cross-sectional and long-term longitudinal studies and it has been found that as prevalence of AD declines, prevalence of AA increases. A similar relationship is reported between AA and AR. The legitimacy of the atopic march model is, however, currently debated. Epidemiological evidence and criticism of longitudinal studies point to an overstatement of the atopic march's prevalence and incorrect mechanisms, opening a discussion for alternative models to better explain the pathophysiological and epidemiological processes that promote this progression of allergic diseases. Albeit, risk factors for the development and progression of allergic disease, particularly AD, are critical in identifying disease progression. Investigating the role of age, severity, family history, phenotype, and genetic traits may give a better indication into the progression of allergic diseases. In addition, studies following patients from infancy into adulthood and a general increase in longitudinal studies would help broaden the knowledge of allergic disease progression and the atopic march.

Shared prenatal impacts among childhood asthma, allergic rhinitis and atopic dermatitis: a population-based study

Background

Increasing prevalence of childhood allergic diseases including asthma is a global health concern, and we aimed to investigate prenatal risk factors for childhood asthma and to address the potential shared prenatal impacts among childhood asthma, allergic rhinitis (AR) and atopic dermatitis (AD).

Methods

We used two claim databases, including Taiwan Birth Cohort Study (TBCS) and National Health Insurance Research Database (NHIRD), to identify independent paired mother–child data (mother–child dyads) between 2006 and 2009. The association between prenatal factors and asthma was determined by calculating adjusted odds ratio (aOR) with 95% confidence interval (CI) using conditional logistic regression analysis.

Results

A total of 628,878 mother–child dyads were included, and 43,915 (6.98%) of children developed asthma prior to age 6. We found that male gender (aOR 1.50, 95% CI 1.47–1.53), maternal asthma (aOR 1.80, 95% CI 1.71–1.89), maternal AR (aOR 1.33, 95% CI 1.30–1.37), preterm birth (aOR 1.32, 95% CI 1.27–1.37), low birth weight (aOR 1.14, 95% CI 1.10–1.19) and cesarean section (aOR 1.10, 95% CI 1.08–1.13) were independent predictors for childhood asthma. A high urbanization level and a low number of older siblings were associated with asthma in a dose–response manner. Notably, we identified that the association between maternal asthma and childhood asthma (aOR 1.80, 95% CI 1.71–1.89) was stronger compared with those between maternal asthma and childhood AR (aOR 1.67, 95% CI 1.50–1.87) as well as childhood AD (aOR 1.31, 95% CI 1.22–1.40). Similarly, the association between maternal AR and childhood AR (aOR 1.62, 95% CI 1.53–1.72) was higher than those between maternal AR and childhood asthma (aOR 1.33, 95% CI 1.30–1.37) as well as childhood AD (aOR 1.35, 95% CI 1.31–1.40). Furthermore, the number of maternal allergic diseases was associated with the three childhood allergic diseases in a dose–response manner.

Conclusions

In conclusion, this population-based study provided evidence of prenatal impacts on childhood asthma and demonstrated the shared maternal impacts among childhood asthma, AR, and AD. These findings highlight the shared prenatal impacts among allergic diseases, and studies are warranted to address the pivotal pathway in allergic diseases.

Allergic Comorbidity in Eosinophilic Esophagitis: Mechanistic Relevance and Clinical Implications

Allergic eosinophilic esophagitis (EoE) is a chronic, allergen-mediated inflammatory disease of the esophagus, and the most common cause of prolonged dysphagia in children and young adults in the developed world. While initially undistinguished from gastroesophageal reflux disease-associated esophageal eosinophilia, EoE is now recognized as a clinically distinct entity that shares fundamental inflammatory features of other allergic conditions and is similarly increasing in incidence and prevalence. The clinical and epidemiologic associations between EoE and other allergic manifestations are well established. In addition to exaggerated rates of atopic dermatitis, IgE-mediated food allergy, asthma, and allergic rhinitis in EoE patients, each of these allergic manifestations imparts individual and cumulative risk for subsequent EoE diagnosis. As such, EoE may be a member of the "allergic march"-the natural history of allergic manifestations during childhood. Several determinants likely contribute to the relationship between these conditions, including shared genetic, environmental, and immunologic factors. Herein, we present a comprehensive review of allergic comorbidity in EoE. We discuss areas of the genome associated with both EoE and other allergic diseases, including the well-studied variants encoding thymic stromal lymphopoietin and calpain 14, among other "atopic" regions. We summarize ways that environmental factors (such as microbiome-altering pressures and aeroallergen exposure) may predispose to multiple allergic conditions including EoE. Finally, we touch on some fundamental features of type 2 inflammation, and the resulting implications for the development of multiple allergic manifestations. We conclude with an analysis of the "type 2" biologics, and how mechanistic similarities between EoE and the other allergic manifestations have important implications for screening and treatment of the allergic patient.

[Prognosis of bronchopulmonary dysplasia in preterm infants: a follow-up during infancy]

OBJECTIVE

To investigate the physical development, incidence of common respiratory diseases, and motor development during infancy in preterm infants with bronchopulmonary dysplasia (BPD).

METHODS

A retrospective analysis was performed on the clinical features and infantile outcomes of preterm infants with BPD who were admitted to the neonatal intensive care unit between January 2012 and December 2015. Preterm infants without BPD were used as controls who were admitted to the neonatal intensive care unit during the same period and had similar gestational age and birth weight. Physical development, number of hospital stays, the incidences of pneumonia and wheezing, and motor development during infancy were compared between the two groups.

RESULTS

Compared with the control group, BPD infants had a significantly higher incidence of extrauterine growth retardation at discharge (48% vs 41%; P<0.05); BPD infants were more susceptible to pneumonia, wheezing, eczema and rhinitis; BDP infants also had a significantly higher number of readmissions due to respiratory tract infection (P<0.05). BPD infants had a significantly smaller head circumference than the control group at corrected ages of 3, 6, and 12 months (P<0.05). BPD infants had significantly delayed gross, fine, and overall motor development than the control group at corrected ages of 6 and 9 months (P<0.05).

CONCLUSIONS

Infants with BPD are susceptible to extrauterine growth retardation at discharge. Their head circumference growth is relatively slow. They are susceptible to pneumonia and wheezing during infancy. Moreover, they have delayed motor development when compared with those without BPD at corrected ages of 6 and 9 months.

[Prognosis of bronchopulmonary dysplasia in preterm infants: a follow-up during infancy]

OBJECTIVE

To investigate the physical development, incidence of common respiratory diseases, and motor development during infancy in preterm infants with bronchopulmonary dysplasia (BPD).

METHODS

A retrospective analysis was performed on the clinical features and infantile outcomes of preterm infants with BPD who were admitted to the neonatal intensive care unit between January 2012 and December 2015. Preterm infants without BPD were used as controls who were admitted to the neonatal intensive care unit during the same period and had similar gestational age and birth weight. Physical development, number of hospital stays, the incidences of pneumonia and wheezing, and motor development during infancy were compared between the two groups.

RESULTS

Compared with the control group, BPD infants had a significantly higher incidence of extrauterine growth retardation at discharge (48% vs 41%; P<0.05); BPD infants were more susceptible to pneumonia, wheezing, eczema and rhinitis; BDP infants also had a significantly higher number of readmissions due to respiratory tract infection (P<0.05). BPD infants had a significantly smaller head circumference than the control group at corrected ages of 3, 6, and 12 months (P<0.05). BPD infants had significantly delayed gross, fine, and overall motor development than the control group at corrected ages of 6 and 9 months (P<0.05).

CONCLUSIONS

Infants with BPD are susceptible to extrauterine growth retardation at discharge. Their head circumference growth is relatively slow. They are susceptible to pneumonia and wheezing during infancy. Moreover, they have delayed motor development when compared with those without BPD at corrected ages of 6 and 9 months.

The allergic phenotype during the first 10 years of life in a prospective cohort

Background

Heredity and environmental parameters jointly affect allergy development. Here, we used a Swedish prospective cohort to study the influence of heredity and factors usually associated with allergic disease and the development of allergic manifestations in combination with immunoglobulin E (IgE) sensitization at four different time points until 10 years of age.

Methods

Parents‐to‐be were characterized concerning allergy and their children (n = 281) were divided based on allergic heredity and followed from birth and clinically examined for IgE‐associated allergic symptoms until 10 years of age. The relation between allergy and early‐life parameters was analyzed by logistic regression. Group‐wise comparisons were made by nonparametrical tests.

Results

Early life eczema and/or asthma in combination with IgE sensitization, was a strong indicator of allergy at a later time point. Further, the early occurrence of multiple allergic symptoms among IgE‐sensitized children predisposed for a more complex allergic phenotype at later ages, independently of allergic heredity. At 10 years of age, allergic children had higher fractional exhaled nitrogen oxide (FeNO) levels, regardless of asthma, and FeNO levels were also influenced by heredity. Birth season was strongly associated with allergy development, but only in children with two allergic parents.

Conclusion

Allergic eczema/asthma in early life, being born during the autumn/winter, having multiple allergic symptoms and two allergic parents were all strong predictors for having allergic diseases at 5 and 10 years of age. However, the allergic march seems to be independent of heredity, as IgE‐mediated allergies follow the same trajectories in children with and without allergic heredity.

Filaggrin and atopic march

There is an increasing number of experimental, genetic and clinical evidence of atopic dermatitis expression as a pre-condition for later development of other atopic diseases such as asthma, food allergy and allergic rhinitis. Atopic dermatitis is a heterogeneous, recurrent childhood disease, also present in the adult age. It is increasingly attributed to systemic features and is characterized by immunological and skin barrier integrity and function dysregulation. To maintain the protective function of the skin barrier, in particular the maintenance of pH, hydration and antimicrobial functions, the filaggrin, among others, plays a significant role. Filaggrin is a multifunctional, histidine-rich, insoluble protein. The lack of filaggrin is associated with various cutaneous (e.g. ichthyosis vulgaris, allergic contact dermatitis) and non-cutaneous (e.g. diabetes, inflammatory conditions of the gastrointestinal tract) diseases and may be a result of genetic, immunological factors combined with environmental factors. In this review we summarised (emphasized) recent findings in understanding the role of filaggrin in atopic dermatitis and other diseases, participants in the atopic march.

Allergy screening in a schoolchildren-based population

BACKGROUND

Schoolchildren screening for allergic diseases may improve early identification and management of atopic children. The aim of this study was to perform a schoolchildren screening program for identification of children with allergic diseases.

METHODS

All parents of children attending to 13 primary schools in the city of Rome were requested to fill in a demographic data form and the ChAt questionnaire. Allergological evaluation was performed in the children with suspect of allergy (ChAt score > 2). Ocular examination was performed to identify signs of allergic conjunctivitis. The presence of allergic symptoms was related to demographic and environmental variables.

RESULTS

A total of 2667 children (mean age: 7.1 ± 1 years) were included, and 2489 (93.3%) parents completed the ChAt questionnaire. Results of ChAt questionnaire showed a previous diagnosis of allergic disease in 637 (25.6%) children and the potential presence of an allergic disease (ChAt score > 2) in 35.1%. Multivariate analysis showed that older age, male gender, and having less than two siblings were associated with higher risk of allergic disease. Visual screening showed the presence of clinical signs of allergic conjunctivitis in 2% of children. Allergologic evaluation in 334 children confirmed the diagnosis of allergic disease in 324 (97%) cases. Among them, 97 (29.9%) did not refer to a previous formal diagnosis of allergic condition.

CONCLUSIONS

This study confirmed that schoolchildren screening using ChAt questionnaire could represent a useful tool for early identification of yet undiagnosed atopic children.

Early immunologic changes during the onset of atopic dermatitis

OBJECTIVE

Atopic dermatitis (AD), which is commonly called eczema, is the most common chronic inflammatory skin disease. The pipeline of new targeted treatments is currently expanding, a development that is largely based on our increasing understanding of disease mechanisms. Mechanistic insights have long been based on long-standing adult AD. Recently, studies also investigated early pediatric AD at disease onset, and revealed several differences in barrier and immune properties when compared with long-standing adult AD. This review focuses on immunological changes very early in life that predispose to the development of AD, and summarizes characteristics of the molecular AD phenotype in this age group.

DATA SOURCES

Review of published literature.

STUDY SELECTIONS

Studies investigating human AD at disease onset in newborns, toddlers, and young children, in comparison with adults with long-standing disease.

RESULTS

Already in cord blood, increased Th2 and decreased Th1 levels were found to increase the risk of AD development. Both pediatric and adult AD share Th2/Th22 activation and defects in lipid barrier deposition and tight junction formation, but Th1 activation and epidermal differentiation complex defects are largely absent in pediatric AD.

CONCLUSION

Immune changes predisposing to AD development are present very early in life. During the first months of disease, AD shows various differences in immune and barrier properties from long-standing adult AD, which might necessitate tailored treatment approaches depending on the age of the patient.

Epithelial barrier repair and prevention of allergy

Allergic diseases have in common a dysfunctional epithelial barrier, which allows the penetration of allergens and microbes, leading to the release of type 2 cytokines that drive allergic inflammation. The accessibility of skin, compared with lung or gastrointestinal tissue, has facilitated detailed investigations into mechanisms underlying epithelial barrier dysfunction in atopic dermatitis (AD). This Review describes the formation of the skin barrier and analyzes the link between altered skin barrier formation and the pathogenesis of AD. The keratinocyte differentiation process is under tight regulation. During epidermal differentiation, keratinocytes sequentially switch gene expression programs, resulting in terminal differentiation and the formation of a mature stratum corneum, which is essential for the skin to prevent allergen or microbial invasion. Abnormalities in keratinocyte differentiation in AD skin result in hyperproliferation of the basal layer of epidermis, inhibition of markers of terminal differentiation, and barrier lipid abnormalities, compromising skin barrier and antimicrobial function. There is also compelling evidence for epithelial dysregulation in asthma, food allergy, eosinophilic esophagitis, and allergic rhinosinusitis. This Review examines current epithelial barrier repair strategies as an approach for allergy prevention or intervention.

Gut Microbiome as Target for Innovative Strategies Against Food Allergy

The dramatic increase in food allergy prevalence and severity globally requires effective strategies. Food allergy derives from a defect in immune tolerance mechanisms. Immune tolerance is modulated by gut microbiota function and structure, and microbiome alterations (dysbiosis) have a pivotal role in the development of food allergy. Environmental factors, including a low-fiber/high-fat diet, cesarean delivery, antiseptic agents, lack of breastfeeding, and drugs can induce gut microbiome dysbiosis, and have been associated with food allergy. New experimental tools and technologies have provided information regarding the role of metabolites generated from dietary nutrients and selected probiotic strains that could act on immune tolerance mechanisms. The mechanisms are multiple and still not completely defined. Increasing evidence has provided useful information on optimal bacterial species/strains, dosage, and timing for intervention. The increased knowledge of the crucial role played by nutrients and gut microbiota-derived metabolites is opening the way to a post-biotic approach in the stimulation of immune tolerance through epigenetic regulation. This review focused on the potential role of gut microbiome as the target for innovative strategies against food allergy.

The skin as a target for prevention of the atopic march

OBJECTIVE

Allergic diseases have increased dramatically in the developed world during the past few decades, yet the understanding of risk factors and effective prevention approaches remain limited. In this review, we summarize the evidence supporting the hypothesis that skin-barrier impairment and early-life atopic dermatitis (AD) could play a causal role in the development of sensitization and subsequent food allergies and allergic airways disease (allergic asthma and rhinitis). We further discuss the potential to target the skin barrier as a means to lower the incidence of allergic disease.

DATA SOURCES

Review of published literature.

STUDY SELECTIONS

Narrative.

RESULTS

There is a strong link between AD and sensitization, food allergy, asthma, and allergic rhinitis, particularly AD that is severe and commences in the first 6 months of life. There also is emerging evidence that regular use of prophylactic emollients can significantly decrease the expression of AD, at least while treatment continues. Studies are exploring whether decreased AD expression might modulate the allergic response at a more fundamental level and potentially alter the association between early-life AD and subsequent development of food allergy and allergic airways disease.

CONCLUSION

Although at this point there is only indirect evidence that early-life emollient use might prevent AD and food allergy, early studies are encouraging. The results of high-quality prevention trials that are in progress are eagerly anticipated. If found to be effective, then neonatal emollient use could be a simple public health measure to lower the incidence of AD, food allergies, and allergic airways disease in future generations.

Report from the National Institute of Allergy and Infectious Diseases workshop on "Atopic dermatitis and the atopic march: Mechanisms and interventions"

Atopic dermatitis (AD) affects up to 20% of children worldwide and is an increasing public health problem, particularly in developed countries. Although AD in infants and young children can resolve, there is a well-recognized increased risk of sequential progression from AD to other atopic diseases, including food allergy (FA), allergic rhinitis, allergic asthma, and allergic rhinoconjunctivitis, a process referred to as the atopic march. The mechanisms underlying the development of AD and subsequent progression to other atopic comorbidities, particularly FA, are incompletely understood and the subject of intense investigation. Other major research objectives are the development of effective strategies to prevent AD and FA, as well as therapeutic interventions to inhibit the atopic march. In 2017, the Division of Allergy, Immunology, and Transplantation of the National Institute of Allergy and Infectious Diseases sponsored a workshop to discuss current understanding and important advances in these research areas and to identify gaps in knowledge and future research directions. International and national experts in the field were joined by representatives from several National Institutes of Health institutes. Summaries of workshop presentations, key conclusions, and recommendations are presented herein.