Predicting the atopic march: Results from the Canadian Healthy Infant Longitudinal Development Study

Combined metagenomic- and culture-based approaches to investigate bacterial strain-level associations with medication-controlled mild-moderate atopic dermatitis

Background

The skin microbiome is disrupted in atopic dermatitis (AD). Existing research focuses on moderate to severe, unmedicated disease.

Objective

We sought to investigate metagenomic- and culture-based bacterial strain-level differences in mild, medicated AD and the effects these have on human keratinocytes (HKs).

Methods

Skin swabs from anterior forearms were collected from 20 pediatric participants (11 participants with AD sampled at lesional and nonlesional sites and 9 age- and sex-matched controls). Participants had primarily mild to moderate AD and maintained medication use. Samples were processed for microbial metagenomic sequencing and bacterial isolation. Isolates identified as Staphylococcus aureus were tested for enterotoxin production. HK cultures were treated with cell-free conditioned media from representative Staphylococcus species to measure barrier effects.

Results

Metagenomic sequencing identified significant differences in microbiome composition between AD and control groups. Differences were seen at the species and strain levels for Staphylococci, with S aureus found only in participants with AD and differences in Staphylococcus epidermidis strains between control and AD swabs. These strains showed differences in toxin gene presence, which was confirmed in vitro for S aureus enterotoxins. The strain from the participant with the most severe AD produced enterotoxin B levels more than 100-fold higher than the other strains (P < .001). Strains also displayed differential effects on HK metabolism and barrier function.

Conclusions

Strain-level differences in toxin genes from Staphylococcus strains may explain varying effects on HK, with S aureus and non-aureus strains negatively affecting viability and barrier function. These differences are likely important in AD pathogenesis.

Pediatric asthma comorbidities: Global impact and unmet needs

Real-world data on the range and impact of comorbid health conditions that affect pediatric asthma are scant, especially from developing countries. Lack of data hinders effective diagnosis, treatment, and overall management of these complex cases. We, hereby, describe the common pediatric asthma comorbid conditions in terms of evidence for association, potential mechanisms of impact on asthma control, and treatment benefit. Obesity, upper airway allergies, dysfunctional breathing, multiple sensitizations, depressive disorders, food allergy, and gastro-esophageal reflux are common associations with difficult-to-treat asthma. On the other hand, asthma symptoms and/or management may negatively impact the well-being of children through drug adverse effects, worsening of anaphylaxis symptoms, and disturbing mental health. Awareness of these ailments may be crucial for designing the optimum care for each asthmatic child individually and may ultimately improve the quality of life of patients and their families. A multidisciplinary team of physicians is required to identify and manage such comorbidities aiming to mitigate the over-use of asthma pharmacotherapy. Asthma research should target relevant real-world difficulties encountered at clinical practice and focus on interventions that would mitigate the impact of such comorbidities. Finally, policymakers and global healthcare organizations are urged to recognize pediatric asthma control as a healthcare priority and allocate resources for research and clinical interventions. In other words, global asthma control needs support by compassionate scientific partnership.

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

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

Potential of Curcumin in the Management of Skin Diseases

Curcumin is a polyphenolic molecule derived from the rhizoma of Curcuma longa L. This compound has been used for centuries due to its anti-inflammatory, antioxidant, and antimicrobial properties. These make it ideal for preventing and treating skin inflammation, premature skin ageing, psoriasis, and acne. Additionally, it exhibits antiviral, antimutagenic, and antifungal effects. Curcumin provides protection against skin damage caused by prolonged exposure to UVB radiation. It reduces wound healing times and improves collagen deposition. Moreover, it increases fibroblast and vascular density in wounds. This review summarizes the available information on the therapeutic effect of curcumin in treating skin diseases. The results suggest that curcumin may be an inexpensive, well-tolerated, and effective agent for treating skin diseases. However, larger clinical trials are needed to confirm these observations due to limitations in its in vivo use, such as low bioavailability after oral administration and metabolism.

Incident Asthma, Asthma Exacerbations, and Asthma-Related Hospitalizations in Patients With Atopic Dermatitis

BACKGROUND

Atopic dermatitis (AD) is thought to induce asthma via the "atopic march," but the effects of AD on incident asthma and asthma severity have not been fully characterized.

OBJECTIVE

To determine risk of asthma, asthma exacerbations, and asthma-related hospitalizations among patients fwith AD.

METHODS

A cohort study was conducted using electronic health records data from UK general practices from 1994 to 2015. Children (<18 years old) and adults (≥18 years) with AD were matched on age, practice, and index date to patients without AD. AD severity was categorized using treatments and dermatologist referrals. Outcomes were incident asthma among all patients and asthma exacerbation or hospitalization among patients with asthma.

RESULTS

On comparing 409,341 children with AD (93.2% mild, 5.5% moderate, 1.3% severe) with 1,809,029 unaffected children, those with AD were found to be associated with a 2-fold greater risk of asthma compared with those without AD (hazard ratio, 1.96; 95% CI, 1.93-1.98). On comparing 625,083 adults with AD (65.7% mild, 31.4% moderate, and 2.9% severe) with 2,678,888 unaffected adults, AD was found to be associated with a 38% higher risk of asthma (hazard ratio, 1.38; 95% CI, 1.36-1.40). Asthmatic patients with AD also had a 21% to 63% greater risk of asthma exacerbations and a 20% to 64% greater risk of asthma-related hospitalizations compared with asthmatic patients without AD. Risk of asthma, asthma exacerbation, or asthma-related hospitalization increased with AD severity in a dose-dependent manner in both the pediatric and adult cohorts.

CONCLUSIONS

AD, especially in children and when more severe, is associated with greater risk of asthma as well as greater risk of asthma exacerbations and hospitalizations among asthmatic patients.

Modification of Food Allergy on the Associations between Early Life Exposure to Size-Specific Particulate Matter and Childhood Allergic Rhinitis

Previous studies have reported the association between particulate matter (PM) and childhood allergic rhinitis (AR). However, it is unclear whether food allergy (FA) modifies the PM-AR association. We aimed at evaluating the effect of the modification of FA on PM-AR association in preschool children. We adopted a cross-sectional study and conducted a questionnaire survey among preschool children aged 3-6 years in 7 cities in China from June 2019 to June 2020 to collect information on AR and FA. We used a combination of multilevel logistic regression and restricted cubic spline functions to quantitatively assess whether FA modifies the associations between size-specific PM exposure (1 × 1 km) and the risk of AR. The adjusted odds ratios (ORs) for AR among the children with FA as per a 10 μg/m3 increase in early life PM1, PM2.5, and PM10 were significantly higher than the corresponding ORs among the children without FA [e.g., OR: 1.58, 95% CI: (1.32, 1.90) vs 1.29, 95% CI: (1.18, 1.41), per 10 μg/m3 increase in PM1]. The interactions between FA and size-specific PM exposure and their effects on AR were statistically significant (all p-int < 0.001). FA, as an important part of the allergic disease progression, may modify the PM-AR association in preschool children.

Global, regional, and national incidence of six major immune-mediated inflammatory diseases: findings from the global burden of disease study 2019

Background

The causes for immune-mediated inflammatory diseases (IMIDs) are diverse and the incidence trends of IMIDs from specific causes are rarely studied. The study aims to investigate the pattern and trend of IMIDs from 1990 to 2019.

Methods

We collected detailed information on six major causes of IMIDs, including asthma, inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, psoriasis, and atopic dermatitis, between 1990 and 2019, derived from the Global Burden of Disease study in 2019. The average annual percent change (AAPC) in number of incidents and age standardized incidence rate (ASR) on IMIDs, by sex, age, region, and causes, were calculated to quantify the temporal trends.

Findings

In 2019, rheumatoid arthritis, atopic dermatitis, asthma, multiple sclerosis, psoriasis, inflammatory bowel disease accounted 1.59%, 36.17%, 54.71%, 0.09%, 6.84%, 0.60% of overall new IMIDs cases, respectively. The ASR of IMIDs showed substantial regional and global variation with the highest in High SDI region, High-income North America, and United States of America. Throughout human lifespan, the age distribution of incident cases from six IMIDs was quite different. Globally, incident cases of IMIDs increased with an AAPC of 0.68 and the ASR decreased with an AAPC of -0.34 from 1990 to 2019. The incident cases increased across six IMIDs, the ASR of rheumatoid arthritis increased (0.21, 95% CI 0.18, 0.25), while the ASR of asthma (AAPC = -0.41), inflammatory bowel disease (AAPC = -0.72), multiple sclerosis (AAPC = -0.26), psoriasis (AAPC = -0.77), and atopic dermatitis (AAPC = -0.15) decreased. The ASR of overall and six individual IMID increased with SDI at regional and global level. Countries with higher ASR in 1990 experienced a more rapid decrease in ASR.

Interpretation

The incidence patterns of IMIDs varied considerably across the world. Innovative prevention and integrative management strategy are urgently needed to mitigate the increasing ASR of rheumatoid arthritis and upsurging new cases of other five IMIDs, respectively.

Funding

The Global Burden of Disease Study is funded by the Bill and Melinda Gates Foundation. The project funded by Scientific Research Fund of Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital (2022QN38).

An update on recent developments and highlights in food allergy

While both the incidence and general awareness of food allergies is increasing, the variety and clinical availability of therapeutics remain limited. Therefore, investigations into the potential factors contributing to the development of food allergy (FA) and the mechanisms of natural tolerance or induced desensitization are required. In addition, a detailed understanding of the pathophysiology of food allergies is needed to generate compelling, enduring, and safe treatment options. New findings regarding the contribution of barrier function, the effect of emollient interventions, mechanisms of allergen recognition, and the contributions of specific immune cell subsets through rodent models and human clinical studies provide novel insights. With the first approved treatment for peanut allergy, the clinical management of FA is evolving toward less intensive, alternative approaches involving fixed doses, lower maintenance dose targets, coadministration of biologicals, adjuvants, and tolerance-inducing formulations. The ultimate goal is to improve immunotherapy and develop precision-based medicine via risk phenotyping allowing optimal treatment for each food-allergic patient.

Infant food allergy phenotypes and association with lung function deficits and asthma at age 6 years: a population-based, prospective cohort study in Australia

BACKGROUND

Food allergy is considered a precursor to asthma in the context of the atopic march, but the relationship between infant food allergy phenotypes and lung function and asthma in childhood is unclear. We aimed to examine the association between food sensitisation and challenge-confirmed food allergy in infancy, as well as persistent and resolved food allergy up to age 6 years, and the risk of lung function deficits and asthma at age 6 years.

METHODS

The longitudinal, population-based HealthNuts cohort study in Melbourne, VIC, Australia, recruited 5276 infants children aged 1 year who attended council-run immunisation sessions between Sept 28, 2007, and Aug 5, 2011. At age 1 year, all children completed skin prick testing to four food allergens (egg, peanut, sesame, and either shrimp or cow's milk) and an oral food challenge (egg, peanut, and sesame) at the Royal Children's Hospital in Melbourne. Parents completed questionnaires about their infant's allergy history, demographic characteristics, and environmental exposures. At age 6 years, children were invited for a health assessment that included skin prick testing for ten foods (milk, egg, peanut, wheat, sesame, soy, shrimp, cashew, almond, and hazelnut) and eight aeroallergens (alternaria, cladasporum, house dust mite, cat hair, dog hair, bermuda grass, rye grass, and birch mix), oral food challenges, and lung function testing by spirometry. Questionnaires completed by parents (different to those completed at age 1 year) captured the child's allergy and respiratory history and demographics. We investigated associations between food allergy phenotypes (food-sensitised tolerance or food allergy; and ever, transient, persistent, or late-onset food allergy), lung function spirometry measures (forced expiratory volume in 1 sec [FEV1] and forced vital capacity [FVC] z-scores, FEV1/FVC ratio, forced expiratory flow at 25% and 75% of the pulmonary volume [FEF25-75%], and bronchodilator responsiveness), and asthma using regression methods. Only children with complete data on the exposure, outcome, and confounders were included in models. Infants without food sensitisation or food allergy at age 1 year and 6 years served as the reference group.

FINDINGS

Of 5276 participants, 3233 completed the health assessment at age 6 years and were included in this analysis. Food allergy, but not food-sensitised tolerance, at age 1 year was associated with reduced FEV1 and FVC (aβ -0·19 [95% CI -0·32 to -0·06] and -0·17 [-0·31 to -0·04], respectively) at age 6 years. Transient egg allergy was associated with reduced FEV1 and FVC compared with never having egg allergy (-0·18 [95% CI -0·33 to -0·03] and -0·15 [-0·31 to 0·00], respectively), whereas persistent egg allergy was not (FEV1 -0·09 [-0·48 to 0·31]; FVC -0·20 [-0·62 to 0·21]). Transient peanut allergy was associated with reduced FEV1 and FVC (FEV1 aβ -0·37 [-0·79 to 0·04] and FVC aβ -0·55 [-0·98 to -0·12]), in addition to persistent peanut allergy (FEV1 aβ -0·30 [-0·54 to -0·06] and FVC aβ-0·30 [-0·55 to -0·05]), and late-onset peanut allergy (FEV1 aβ -0·62 [-1·06 to -0·18] and FVC aβ-0·49 [-0·96 to -0·03]). Estimates suggested that food-sensitised tolerance and food allergy were associated with reduced FEF25-75%, although some estimates were imprecise. Food allergy phenotypes were not associated with an FEV1/FVC ratio. Late-onset peanut allergy was the only allergy phenotype that was possibly associated with increased risk of bronchodilator responsiveness (2·95 [95% CI 0·77 to 11·38]). 430 (13·7%) of 3135 children were diagnosed with asthma before age 6 years (95% CI 12·5-15·0). Both food-sensitised tolerance and food allergy at age 1 year were associated with increased asthma risk at age 6 years (adjusted odds ratio 1·97 [95% CI 1·23 to 3·15] and 3·69 [2·81 to 4·85], respectively). Persistent and late-onset peanut allergy were associated with higher asthma risk (3·87 [2·39 to 6·26] and 5·06 [2·15 to 11·90], respectively).

INTERPRETATION

Food allergy in infancy, whether it resolves or not, is associated with lung function deficits and asthma at age 6 years. Follow-up studies of interventions to prevent food allergy present an opportunity to examine whether preventing these food allergies improves respiratory health.

FUNDING

National Health & Medical Research Council of Australia, Ilhan Food Allergy Foundation, AnaphylaxiStop, the Charles and Sylvia Viertel Medical Research Foundation, the Victorian Government's Operational Infrastructure Support Program.

The SunBEAm birth cohort: Protocol design

Background

Food allergy (FA) and atopic dermatitis (AD) are common conditions that often present in the first year of life. Identification of underlying mechanisms and environmental determinants of FA and AD is essential to develop and implement effective prevention and treatment strategies. Objectives: We sought to describe the design of the Systems Biology of Early Atopy (SunBEAm) birth cohort.

Methods

Funded by the National Institute of Allergy and Infectious Diseases (NIAID) and administered through the Consortium for Food Allergy Research (CoFAR), SunBEAm is a US population-based, multicenter birth cohort that enrolls pregnant mothers, fathers, and their newborns and follows them to 3 years. Questionnaire and biosampling strategies were developed to apply a systems biology approach to identify environmental, immunologic, and multiomic determinants of AD, FA, and other allergic outcomes.

Results

Enrollment is currently underway. On the basis of an estimated FA prevalence of 6%, the enrollment goal is 2500 infants. AD is defined on the basis of questionnaire and assessment, and FA is defined by an algorithm combining history and testing. Although any FA will be recorded, we focus on the diagnosis of egg, milk, and peanut at 5 months, adding wheat, soy, cashew, hazelnut, walnut, codfish, shrimp, and sesame starting at 12 months. Sampling includes blood, hair, stool, dust, water, tape strips, skin swabs, nasal secretions, nasal swabs, saliva, urine, functional aspects of the skin, and maternal breast milk and vaginal swabs.

Conclusions

The SunBEAm birth cohort will provide a rich repository of data and specimens to interrogate mechanisms and determinants of early allergic outcomes, with an emphasis on FA, AD, and systems biology.

Genomic, Epigenomic, Transcriptomic, Proteomic and Metabolomic Approaches in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a high prevalence in the developed countries. It is associated with atopic and non-atopic diseases, and its close correlation with atopic comorbidities has been genetically demonstrated. One of the main roles of genetic studies is to comprehend the defects of the cutaneous barrier due to filaggrin deficit and epidermal spongiosis. Recently, epigenetic studies started to analyze the influence of the environmental factors on gene expression. The epigenome is considered to be a superior second code that controls the genome, which includes alterations of the chromatin. The epigenetic changes do not alter the genetic code, however, changes in the chromatin structure could activate or inhibit the transcription process of certain genes and consequently, the translation process of the new mRNA into a polypeptide chain. In-depth analysis of the transcriptomic, metabolomic and proteomic studies allow to unravel detailed mechanisms that cause AD. The extracellular space and lipid metabolism are associated with AD that is independent of the filaggrin expression. On the other hand, around 45 proteins are considered as the principal components in the atopic skin. Moreover, genetic studies based on the disrupted cutaneous barrier can lead to the development of new treatments targeting the cutaneous barrier or cutaneous inflammation. Unfortunately, at present, there are no target therapies that focus on the epigenetic process of AD. However, in the future, miR-143 could be an important objective for new therapies, as it targets the miR-335:SOX axis, thereby restoring the miR-335 expression, and repairing the cutaneous barrier defects.

Analysis of Multimorbidity of Moderate to Severe Allergic Rhinitis in Children: A Real-World Study

INTRODUCTION

Allergic rhinitis (AR) in children is associated with various comorbidities, posing challenges for treatment and management. There have been few investigations of these multimorbidities in Chinese children with AR. Here, we investigated the prevalence of multimorbidities in children with moderate to severe AR and analyzed the influencing factors using real-world data.

METHODS

In total, 600 children who visited the outpatient clinic of our hospital and were diagnosed with moderate-severe AR were prospectively enrolled. All children underwent allergen detection and electronic nasopharyngoscopy. Parents or guardians completed a questionnaire that included age, sex, mode of delivery, feeding pattern, and familial history of allergy. The multimorbidities investigated included atopic dermatitis (AD), asthma, allergic conjunctivitis (AC), chronic rhinosinusitis (CRS), adenoid hypertrophy (AH), tonsil hypertrophy (TH), recurrent epistaxis, and recurrent respiratory tract infections (RRTIs).

RESULTS

The AR multimorbidities reported in children were as follows: recurrent epistaxis (46.5%), AC (46.3%), AD (40.7%), asthma (22.5%), RRIs (21.3%), CRS (20.5%), AH (19.7%), and TH (12.5%). In univariate logistic regression analysis, age (<6 years), birth mode, familial history of allergy, and single dust mite allergy were associated with AR multimorbidity (p < 0.05). Multivariate logistic regression revealed that a familial history of allergy was an independent risk factor for AC (odds ratio [OR] = 1.539, 95% confidence interval [CI]: 1.104-2.145) and AH (OR = 1.506, 95% CI: 1.000-2.267) (p < 0.05). Age (<6 years) was independently associated with the risk of AD (OR = 1.405, 95% CI: 1.003-1.969) and RRTIs (OR = 1.869, 95% CI: 1.250-2.793) (p < 0.05), cesarean section with AR and CRS risk (OR = 1.678, 95% CI: 1.100-2.561), and single dust mite allergy with asthma (OR = 1.590, 95% CI: 1.040-2.432) and CRS (OR = 1.600, 95% CI: 1.018-2.515) risk (p < 0.05). Further, non-dust mite allergy was independently associated with AR and CRS (OR = 2.056, 95% CI: 1.084-3.899).

CONCLUSION

AR was found to be accompanied by different comorbidities, including both allergic and non-allergic comorbidities, complicating disease treatment. These findings demonstrated that age (<6 years), familial history of allergy, types of allergens, and cesarean section were risk factors for different multimorbidities associated with AR.

Might biologics serve to interrupt the atopic march?

The atopic march was described more than 20 years ago on the basis of initial observations, and it is now seen in prospective studies. The concept has evolved and is now considered to be the progression of atopic dermatitis to other atopic conditions, including asthma, allergic rhinitis, food allergy, and eosinophilic esophagitis in a nonlinear fashion. The progression can include some or all of the aforementioned atopic conditions. The pathogenesis is part of the classic type 2 inflammatory process involving IL-4, IL-5, and IL-13 preceded by induction of the alarmins (thymic stromal lymphopoietin, IL-33, and IL-25), leading to production of IgE in a genetically predisposed individual. The development of new biologics that interact with T2 pathway represent possible ways to prevent or modify the atopic march.

Allergic March in Children: The Significance of Precision Allergy Molecular Diagnosis (PAMD@) in Predicting Atopy Development and Planning Allergen-Specific Immunotherapy

The allergic march is a progression of naturally occurring symptoms whose nature changes with age. The classic allergic march typically begins in infancy and manifests in the form of atopic dermatitis and food allergy. As immune tolerance develops over time, these conditions may resolve by the age of 3-5 years; however, they may evolve into allergic rhinitis and bronchial asthma. Traditional diagnostic assessments, such as skin prick testing or serum allergen-specific immunoglobulin E (sIgE) level testing, are conducted to introduce effective treatment. Recent years saw the emergence of precision allergy molecular diagnosis (PAMD@), which assesses sIgE against allergenic molecules. This new technology helps more accurately evaluate the patient's allergy profile, which helps create more precise dietary specifications and personalize allergen-specific immunotherapy. This review presents possible predictions regarding the allergic march and the means of controlling it based on PAMD@ results.

Natural Green Spaces, Sensitization to Allergens, and the Role of Gut Microbiota during Infancy

The environment plays an instrumental role in the developmental origins of health and disease. Protective features of the environment in the development of asthma and atopy have been insufficiently studied. We used data from the CHILD (Canadian Healthy Infant Longitudinal Development) Cohort Study to examine relationships between living near natural green spaces in early infancy in Edmonton, AB, Canada and the development of atopic sensitization at 1 year and 3 years of age in a cohort of 699 infants, and whether these associations were mediated by infant gut microbiota (measured using 16s V4 amplicon sequencing) at 4 months. The Urban Planning Land Vegetation Index (uPLVI) map of the City of Edmonton was used to assess infants' exposure to natural spaces based on their home postal codes, and atopic sensitization was assessed using skin prink testing (SPTs) for common food and inhalant allergens. Our findings suggest there is a protective effect of natural green space proximity on the development of multiple inhalant atopic sensitizations at 3 years (odds ratio = 0.28 [95% CI 0.09, 0.90]). This relationship was mediated by changes to Actinobacteria diversity in infant fecal samples taken at 4 months. We also found a positive association between nature proximity and sensitization to at least one food or inhaled allergen; this association was not mediated by gut microbiota. Together, these findings underscore the importance of promoting natural urban greenspace preservation to improve child health by reducing atopic disease susceptibility. IMPORTANCE Our findings highlight the importance of preserving natural green space in urban settings to prevent sensitization to environmental allergens and promote early-life gut microbiota pathways to this health benefit. These findings support a mediating role of gut microbiome compositions in health and disease susceptibility. This study used unique, accurate, and comprehensive methodology to classify natural space exposure via a high-resolution topographical map of foliage subtypes within the City of Edmonton limits. These methods are improvements from other methods previously used to classify natural space exposure, such as the normalized density vegetation index from satellite imagery, which is not able to distinguish anthropogenic from green space. The use of these methods and the associations found between natural green space exposure and atopic sensitization outcomes support their use in future studies. Our findings also provide many avenues for future research including longer term follow up of this cohort and investigation of a causal role of reduced Actinobacteria diversity on atopic sensitization development.

Reflectance Confocal Microscopy in Monitoring Atopic Dermatitis Treated with Topical Calcineurin Inhibitors

Atopic dermatitis is a chronic inflammatory skin disease associated with multiple allergies in the atopic march. It has a complex pathogenesis, related to genetic, immune, and environmental factors. Its incidence and prevalence are increasing in the last decades, especially in developed countries. It affects the quality of life due to the recurrent lesions and the associated pruritus. Thus, it is very important to use non-invasive techniques to manage and follow-up the patients with such a heterogenous disease that can have a high impact on some of them. The reflectance confocal microscope is a modern device for in vivo visualization of the epidermis and the upper dermis which could replace in some cases the cutaneous biopsy. We report a case of a patient with atopic dermatitis investigated with the confocal reflectance microscope at the beginning of the topical treatment with calcineurin inhibitors and three weeks after, with favorable evolution. Reflectance confocal microscopy allows the assessment of the dynamic changes in the skin during treatment. Moreover, it can be useful for highlighting discrete changes even in the subclinical stages of the inflammatory process. Future developments, which will lead to the definition and validation of reflectance confocal microscopy criteria for the diagnosis and staging of atopic dermatitis, could help to improve the treatment and prevention strategies of the disease.

Biomarkers associated with the development of comorbidities in patients with atopic dermatitis: A systematic review

Biomarkers associated with the development of comorbidities in atopic dermatitis (AD) patients have been reported, but have not yet been systematically reviewed. Seven electronic databases were searched, from database inception to September 2021. English language randomized controlled trials, prospective and retrospective cohort, and case-control studies that investigated the association between a biomarker and the development of comorbidities in AD patients were included. Two authors independently screened the records for eligibility, one extracted all data, and critically appraised the quality of studies and risk of bias. Fifty six articles met the inclusion criteria, evaluating 146 candidate biomarkers. The most frequently reported biomarkers were filaggrin mutations and allergen specific-IgE. Promising biomarkers include specific-IgE and/or skin prick tests predicting the development of asthma, and genetic polymorphisms predicting the occurrence of eczema herpeticum. The identified studies and biomarkers were highly heterogeneous, and associated with predominately moderate-to-high risk of bias across multiple domains. Overall, findings were inconsistent. High-quality studies assessing biomarkers associated with the development of comorbidities in people with AD are lacking. Harmonized datasets and independent validation studies are urgently needed.

Succinate and mitochondrial DNA trigger atopic march from atopic dermatitis to intestinal inflammation

BACKGROUND

Atopic march has long been recognized as the progression from atopic dermatitis (AD) to food allergy and asthma during infancy and childhood. However, effective blocking is hampered by the lack of specific biomarkers.

OBJECTIVES

We aimed to investigate the pathologic progression of atopic march trajectories from skin to gut.

METHODS

We built an atopic march mouse model by mechanical skin injury and percutaneous sensitization to peanut allergen. Anaphylaxis from the skin to the small intestine was then investigated by ELISA, RNA sequencing, quantitative real-time PCR, histopathologic analysis, and flow cytometry. The findings from the mice results were also verified by the serum samples of allergic pediatric patients.

RESULTS

After modeling, inflammation in the skin and small intestine manifested as a mixed type of T_H2 and T_H17. Further analysis identified elevated succinate in the circulation and expanded tuft cells with upregulated IL-25 in the small intestine, resulting in increased intestinal type 2 innate lymphoid cells and an enhanced type 2 inflammatory response. In addition, free mitochondrial DNA (mtDNA) released after tissue damage was also involved in inflammation march from injured skin to small intestine through the STING pathway. Analysis of clinical samples verified that serum concentrations of succinate and mtDNA were higher in AD allergic children than non-AD allergic children.

CONCLUSIONS

Succinate and mtDNA play key roles in skin-to-gut cross talk during the atopic march from AD to food allergy, and can be considered as biomarkers for risk assessment or targets for atopic march prevention strategies.

Endotoxin concentration and persistent eczema in early childhood

Although endotoxin concentration in the environment is negatively associated with atopic dermatitis (AD) onset in early childhood, the association between endotoxin concentration in the environment and eczema resolution in children with preexisting eczema is unclear. The aim of this study was to evaluate the association between endotoxin concentration in house dust and eczema persistence in young children. The authors used data from children participating in JECS (Japan Environment and Children's Study). In children who had AD or AD-like lesions at the age of 1 year, the authors investigated the association between the prevalence of eczema at the age of 3 years and endotoxin concentration (categorized by quartiles) in the dust on children's mattresses at the ages of 1.5 and 3 years. This study included 605 children. Eczema was significantly less prevalent among children whose mattresses were in the second and third quartiles of endotoxin concentration when they were 18 months old than among children whose mattresses were in the first quartile (adjusted odds ratio, 0.57 [95% confidence interval, 0.35-0.93] and adjusted odds ratio, 0.49 [95% confidence interval, 0.29-0.83], respectively). Moreover, of the children with eczema at age 3 years, those whose mattresses had endotoxin concentrations in the first quartile had significantly worse sleep disturbance caused by itchy rash (>1 time per week) than did those whose mattresses were in the third and fourth quartiles (20.0% vs 3.3% and 3.7%, both p values < 0.01). The findings indicate that low endotoxin exposure is associated with a higher prevalence of persistent eczema during early childhood.

Phenotype of Atopic Dermatitis With Food Allergy Predicts Development of Childhood Asthma via Gut Wnt Signaling

PURPOSE

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by a wide spectrum of clinical phenotype. However, specific description of phenotypes of AD depending on the comorbidities in early childhood is lacking. This study aimed to investigate whether the AD phenotype in early childhood is related to childhood asthma and to elucidate the mechanisms involved.

METHODS

Data on the first 3 years of life were collected prospectively from 1,699 children in the COhort for Childhood Origin of Asthma and allergic diseases (COCOA). We applied an unsupervised latent class analysis to the following five factors: food sensitization, inhalant sensitization, food allergy (FA), AD, and recurrent wheezing. The risks of developing FA, AD, allergic rhinitis (AR), and asthma in children aged 5-7 years were evaluated. Colonocyte transcriptome and ingenuity pathway analysis were performed.

RESULTS

Four phenotypes were identified; no allergic diseases (78.4%), AD without sensitization (16.4%), FA with AD (2.9%), and AD with sensitization (7.8%). The FA with AD had the highest risk for FA, AR, and asthma and the highest cord blood immunoglobulin E (IgE) levels. In AD without sensitization and with sensitization, scoring of AD (SCORAD) in early childhood was higher than in FA with AD. Canonical pathway analysis with the colonocyte transcriptome revealed that the key pathway in FA with AD was 'Wnt/β-catenin Signaling.' The relative abundance of Wnt6 mRNA was positively correlated with food-specific IgE levels at 1 and 3 years.

CONCLUSIONS

When FA is present in various phenotypes of AD at early life, regardless of severity of eczema, it may be associated with gut Wnt signaling and later development of asthma.

Effect of early atopic sensitization in children aged 0-2 years on the development of asthma symptoms at 9-11 years of age

BACKGROUND

Personal genetic predisposition and early life environmental factors are important for the development of childhood asthma. We aimed to search whether egg, milk and mite sensitizations at 0-2 years old are risk factors for asthma symptoms at 9-11 years old.

METHODS

A total of 210 wheezer children who had specific immunoglobulin (Ig) E in 2010-2012 were included in the study (followed by pediatric allergy). Patients were divided into non-atopic (group 1, n = 157) and atopic patients [groups 2-7, n = 53 (5 patients were in both group 4 and group 5)] based on sensitizations. Using the International Study of Asthma and Allergy in Childhood questionnaire, current wheeze (CW, 2nd question), exercise wheezing (EW, 7th question), and dry cough (DC, 8th question) were surveyed. Also, parental allergies, eczema at 0-2 years, current eosinophil percentage and total IgE were recorded.

RESULTS

Eczema was observed as an important risk factor [CW: odds ratio (OR) = 2.83, 95% confidence interval (CI) = 1.54-5.23, P ≤ 0.001; EW: OR = 2.71, 95% CI = 1.33-5.54, P = 0.006; DC: OR = 3.03, 95% CI = 1.47-6.25, P = 0.003], whereas having no atopic sensitization at 0-2-year-old (group 1) was found as a significant protective factor for asthma at 9-11 years old (CW: OR = 0.32, 95% CI = 0.15-0.70, P = 0.004; EW: OR = 0.21, 95% CI 0.10-0.44, P ≤ 0.001; DC: OR = 0.25, 95% CI = 0.10-0.59, P = 0.002).

CONCLUSION

Early personal eczema is a significant risk factor for the development of asthma symptoms at 9-11 years old, whereas not having an allergic sensitization at 0-2 years old (group 1) is an important protective factor.

The human milk proteome and allergy of mother and child: Exploring associations with protein abundances and protein network connectivity

Background

The human milk proteome comprises a vast number of proteins with immunomodulatory functions, but it is not clear how this relates to allergy of the mother or allergy development in the breastfed infant. This study aimed to explore the relation between the human milk proteome and allergy of both mother and child.

Methods

Proteins were analyzed in milk samples from a subset of 300 mother-child dyads from the Canadian CHILD Cohort Study, selected based on maternal and child allergy phenotypes. For this selection, the definition of "allergy" included food allergy, eczema, allergic rhinitis, and asthma. Proteins were analyzed with non-targeted shotgun proteomics using filter-aided sample preparation (FASP) and nanoLC-Orbitrap-MS/MS. Protein abundances, based on label-free quantification, were compared using multiple statistical approaches, including univariate, multivariate, and network analyses.

Results

Using univariate analysis, we observed a trend that milk for infants who develop an allergy by 3 years of age contains higher abundances of immunoglobulin chains, irrespective of the allergy status of the mother. This observation suggests a difference in the milk's immunological potential, which might be related to the development of the infant's immune system. Furthermore, network analysis showed overall increased connectivity of proteins in the milk of allergic mothers and milk for infants who ultimately develop an allergy. This difference in connectivity was especially noted for proteins involved in the protein translation machinery and may be due to the physiological status of the mother, which is reflected in the interconnectedness of proteins in her milk. In addition, it was shown that network analysis complements the other methods for data analysis by revealing complex associations between the milk proteome and mother-child allergy status.

Conclusion

Together, these findings give new insights into how the human milk proteome, through differences in the abundance of individual proteins and protein-protein associations, relates to the allergy status of mother and child. In addition, these results inspire new research directions into the complex interplay of the mother-milk-infant triad and allergy.

Vitamin D Supplementation and Allergic Diseases during Childhood: A Systematic Review and Meta-Analysis

We performed a systematic review and meta-analysis to investigate the effects of vitamin D (VitD) supplementation on children with allergic diseases. MEDLINE, Embase, Web of Science, the Cochrane library, and three Chinese databases were searched up to 15 August 2022. Randomized controlled trials (RCTs) comparing a VitD supplementation versus a placebo for children with allergic diseases were included. Thirty-two RCTs with 2347 participants were included. VitD supplementation did not reduce the risk of asthma exacerbations in children compared with placebo overall (risk ratio (RR) = 0.84, 95% confidence interval (CI): 0.65 to 1.08, p = 0.18), but reduced the risk of asthma exacerbation in children with baseline serum 25(OH)D of <10 ng/mL compared with placebo (RR = 0.48, 95% CI: 0.28 to 0.83, p = 0.009). VitD supplementation significantly reduced Scoring Atopic Dermatitis or the Eczema Area and Severity Index scores in children with atopic dermatitis compared with placebo (standard mean difference = −0.5, 95% CI: −0.87 to −0.12, p = 0.009). VitD supplementation also reduced the symptom-medication score in children with allergic rhinitis compared with placebo (mean (standard deviation): 43.7 (3.3) vs. 57.8 (4.4), p = 0.001). In conclusion, VitD supplementation did not reduce asthma exacerbation risk in children overall but may reduce asthma exacerbation risk in children with serum 25(OH)D concentration < 10 ng/mL. VitD supplementation reduces the severity of atopic dermatitis and symptoms of allergic rhinitis in children.

Atopic Dermatitis With Coexisting Food Allergy in Early Life Is Associated With Childhood Asthma

PURPOSE

Atopic dermatitis (AD) and food allergy (FA) are associated with respiratory comorbidities, in the concept of 'atopic march.' However, children with AD and a coexisting FA have various disease courses, and the mechanism of atopic march remains unclear. In this study, we investigated whether the phenotype of AD with coexisting FA in early life affected asthma or allergic rhinitis (AR) in school children.

METHODS

A total of 1,579 children from the Panel Study on Korean Children (PSKC) cohort were followed-up in 2013. The participants diagnosed with AD in this cohort were classified by the age of AD onset and persistence as well as FA history. We compared the presence of comorbidities-asthma and rhinitis-among different AD phenotypes.

RESULTS

Asthma and AR with current symptoms within 12 months at age 6-8 years were associated with early-onset persistent AD phenotype, regardless of coexisting FA. AD with FA conferred a higher risk of recent wheezing at 8 years of age than AD without FA (adjusted odds ratio, 8.09; 95% confidence interval, 2.54-25.76). Children with early-onset persistent AD with FA manifested a distinctive trajectory with a higher prevalence of wheezing and AR at age 5-8 years than those without AD.

CONCLUSIONS

AD with FA in early life is strongly associated with asthma and AR in school children, and the early-onset persistent AD with FA had a strong additive effect on the risk of asthma at school age. Classifying AD phenotypes regarding FA in early life will help predict and prevent asthma and AR in school children.

Context-dependent function of TSLP and IL-1β in skin allergic sensitization and atopic march

Atopic diseases, including atopic dermatitis (AD) and asthma, affect a large proportion of the population, with increasing prevalence worldwide. AD often precedes the development of asthma, known as the atopic march. Allergen sensitization developed through the barrier-defective skin of AD has been recognized to be a critical step leading to asthma, in which thymic stromal lymphopoietin (TSLP) was previously shown to be critical. In this study, using a laser-assistant microporation system to disrupt targeted skin layers for generating micropores at a precise anatomic depth of mouse skin, we model allergen exposure superficially or deeply in the skin, leading to epicutaneous sensitization or dermacutaneous sensitization that is associated with a different cytokine microenvironment. Our work shows a differential requirement for TSLP in these two contexts, and identifies an important function for IL-1β, which is independent of TSLP, in promoting allergen sensitization and subsequent allergic asthma.

Allergic sensitisation in the skin can lead to allergic dermatitis and further to airway asthma in a process of atopic march. Here the authors examine the difference between superficial or deep skin sensitisation, characterise the immune cells generated and show differential TSLP and IL-1β involvement.

Risk factors for food sensitization in children with atopic dermatitis: a single-center cross-sectional study

OBJECTIVES

To study the risk factors for food sensitization and the influence of food sensitization on quality of life and clinical signs in children with atopic dermatitis (AD).

METHODS

A retrospective analysis was performed on the medical data of 241 children with AD, including demographic features, age of onset, severity of AD, quality of life, physical examination results, skin prick test (SPT) results, serum total IgE levels, and eosinophil count. According to the results of SPT, the children were divided into a food sensitization group (n=127) and a non-food sensitization group (n=114). The multivariate logistic regression analysis was used to identify the risk factors for food sensitization in children with AD.

RESULTS

The prevalence rate of food sensitization was 52.7% (127/241) in the children with AD. The multivariate logistic regression analysis showed that birth in autumn or winter, age of onset of AD<12 months, severe AD, and total IgE>150 IU/mL were risk factors for food sensitization (P<0.05). Compared with the non-food sensitization group, the food sensitization group had a significantly poorer quality of life (P=0.008) and significantly higher prevalence rates of non-specific hand/foot dermatitis and palmar hyperlinearity (P<0.05). Compared with the single food sensitization group, the multiple food sensitization group had more severe AD and a significantly higher proportion of children with exclusive breastfeeding or total IgE>150 IU/mL (P<0.05).

CONCLUSIONS

The AD children born in autumn or winter, or those with early onset (<12 months), severe AD or total IgE>150 IU/mL have a higher risk of food sensitization. The AD children with food sensitization have a poorer quality of life and are more likely to develop non-specific hand/foot dermatitis and palmar hyperlinearity.

Pathways of atopic disease and neurodevelopmental impairment: assessing the evidence for infant antibiotics

INTRODUCTION

Epidemiologic studies are starting to report associations between antibiotic use in early life and neurodevelopmental disorders. Through mechanisms within the gut microbiota-brain axis, indeed, it is plausible that infant antibiotic treatment plays a role in the development of atopic disease and neurodevelopmental disorders.

AREAS COVERED

This narrative review summarizes and interprets published evidence on infant antibiotic use in future outcomes of atopic disease, and neurodevelopmental delay and disorders, including attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). To this end, we critically assess study bias from 2 main confounding factors, maternal/infant infection and infant feeding status. We also discuss common mechanisms that link atopy and neurodevelopment, and propose hypotheses related to immune activation and the gut microbiome.

EXPERT OPINION

Atopic disease and neurodevelopmental disorders share many risk factors and biological pathways. Infant antibiotic use has been linked to both disorders and is likely a marker for prenatal or infant infection. The mediating role of breastfeeding can also not be discounted. The exploration of causal pathways along the gut-brain axis leading towards neurodevelopmental impairment is evolving and of future interest.

Pollen Food Allergy Syndrome in Allergic March

The association between pollen food allergy syndrome (PFAS) and allergic march remains unclear. In this prospective cohort study of the general population in Tokyo (T-Child Study), we found that sensitization to Cry j 1 and Fel d 1 at ages 5 and 9 years was associated with an increased risk of PFAS at 13 years old (at 5 years, Cry j 1: adjusted odds ratio aOR, 2.74; 95% confidence interval CI, 1.53–4.91; Fel d 1: aOR, 2.61; 95% CI, 1.31–5.19; at 9 years, Cry j 1: adjusted odds ratio aOR, 4.28; 95% confidence interval CI, 1.98–9.25; Fel d 1: aOR, 2.40; 95% CI, 1.33–4.32). In particular, sensitization to Bet v 1 at ages 5 and 9 years was associated with a strong risk of PFAS at the age of 13 years (at 5 years: aOR, 10.6; 95% CI, 2.64–42.5; at 9 years: aOR, 9.1; 95% CI, 4.71–17.6). PFAS risk by age 13 years was increased by any allergic symptom at 5 or 9 years, a combination of wheezing, eczema, and rhinitis, and Bet v 1 sensitization. Our findings suggest that PFAS may be associated with allergic march.

Prevalence of eczema between cesarean-born and vaginal-born infants within 1 year of age: a systematic review and meta-analysis

This study aims to quantify the difference in prevalence of eczema between cesarean-born and vaginal-born infants within 1 year of age through a systematic review and meta-analysis. Six electronic databases were searched from inception to August 31, 2021. Studies were included if they reported the prevalence of eczema in infants within 1 year of age with specified mode of delivery. The quality of included studies was assessed using the Joanna Briggs Instrument Critical Appraisal Checklist. Pooled prevalence and odds ratio (OR) were estimated by meta-analyses of included studies. Meta-regression was conducted to explore factors affecting heterogeneity of the prevalence of eczema. Nine studies were included with 3,758 cesarean-born infants and 9,631 vaginal-born infants. The prevalence of eczema in cesarean-born infants [27.8%; 95% confidence interval (CI): 17.7-39.2] was higher than in vaginal-born infants (20.1%; 95% CI: 13.9-28.1), with a pooled OR of 1.31 (95% CI: 1.04-1.65). Subgroup analyses showed that the prevalence of eczema in cesarean-born infants varied according to country, study design, and method of ascertainment. Additionally, the pooled prevalence of eczema in vaginal-born infants differed by age at which eczema was identified. Meta-regression analysis showed that study design and eczema ascertainment method were significant sources of heterogeneity.

CONCLUSION

About 28% of cesarean-born infants within 1 year of age developed eczema, significantly higher than the 20% rate or occurrence seen in vaginal-born infants.

PROTOCOL REGISTRATION

CRD 42,020,152,437.

WHAT IS KNOWN

• Eczema, a complex inflammatory cutaneous disorder characterized by immune mediated inflammation and epidermal barrier dysfunction, is one of the most common allergic disorders in infants. • Eczema may increase the risk of immune-mediated inflammatory disease such as food allergy, asthma, and allergic rhinitis, leading to psychological and social burdens on affected individuals and their families. • Mode of delivery may be associated with the risk of developing eczema, although further studies are needed to clarify such differences.

WHAT IS NEW

• This is the first systematic review designed to estimate the prevalence of eczema in cesarean- and vaginal-born infants within 1 year of age. • Cesarean delivery may increase the risk of developing eczema in infants within the first year of life.

From Skin Barrier Dysfunction to Systemic Impact of Atopic Dermatitis: Implications for a Precision Approach in Dermocosmetics and Medicine

: Atopic dermatitis (AD) affects up to 20% of children and is considered the starting point of the atopic march with the development of food allergy, asthma, and allergic rhinitis. The heterogeneous phenotype reflects distinct and/or overlapping pathogenetic mechanisms with varying degrees of epidermal barrier disruption, activation of different T cell subsets and dysbiosis of the skin microbiome. Here, we review current evidence suggesting a systemic impact of the cutaneous inflammation in AD together with a higher risk of asthma and other comorbidities, especially in severe and persistent AD. Thus, early therapy of AD to restore the impaired skin barrier, modified microbiome, and target type 2 inflammation, depending on the (endo)phenotype, in a tailored approach is crucial. We discuss what we can learn from the comorbidities and the implications for preventive and therapeutic interventions from precision dermocosmetics to precision medicine. The stratification of AD patients into biomarker-based endotypes for a precision medicine approach offers opportunities for better long-term control of AD with the potential to reduce the systemic impact of a chronic skin inflammation and even prevent or modify the course, not only of AD, but possibly also the comorbidities, depending on the patient’s age and disease stage.

Moderate-to-severe lower respiratory tract infection in early life is associated with increased risk of polysensitization and atopic dermatitis: Findings from the CHILD Study

Background

Respiratory infections in infancy are associated with the development of allergic asthma and atopy. Delineating whether symptomatic infections are a marker of atopic predisposition or contribute to atopic development is important for preventive strategies. We hypothesized that early, severe lower respiratory tract infections (LRTIs) may be a risk factor for the development of atopic disease.

Objective

Our aim was to determine whether clinically defined, moderate-to-severe LRTIs in infancy are associated with the development of atopic dermatitis and allergic sensitization at preschool age.

Methods

LRTI timing and severity in the first 18 months of life was defined by using the Canadian Healthy Infant Longitudinal Development study questionnaires. Polysensitization and atopic dermatitis were determined by standardized skin prick testing and structured clinical assessments. Longitudinal associations between LRTI severity and clinical outcomes at ages 3 years and 5 years were determined by adjusted repeated measures generalized estimation equations.

Results

Moderate-to-severe LRTIs were associated with increased odds of polysensitization (odds ratio = 1.91 [95% CI = 1.16-3.15]; P = .014) and atopic dermatitis (odds ratio = 2.19 [95% CI 1.41-3.39]; P < .001) as compared with the odds in children with no history of LRTI in the first 18 months of life. The association between moderate-to-severe LRTI and polysensitization or atopic dermatitis remained robust after adjusting for sex; study site; breast-feeding duration; and mother, father, or both-parent atopy or asthma.

Conclusions

These results highlight severe infant LRTI as an important risk factor for allergic and atopic disease (ie, polysensitization and atopic dermatitis), and they suggest that this risk is independent of maternal in utero environment, both-parent history of asthma, and both-parent genetic predisposition.

Impaired skin barrier and allergic sensitization in early infancy

BACKGROUND

Factors predicting allergic sensitization in the first 6 months of life are poorly understood. We aimed to determine whether eczema, dry skin, and high transepidermal water loss (TEWL) at 3 months were associated with allergic sensitization at 6 months of age and, secondarily, to establish whether these characteristics predicted sensitization from 3 to 6 months of age.

METHODS

At 3 months of age, 1,994 infants from the population-based PreventADALL birth cohort in Norway and Sweden were assessed for eczema and dry skin on the cheeks and/or extensors; impaired skin barrier function, defined as TEWL in the upper quartile (>9.4 g/m² /h), and allergen-specific IgE levels <0.1 kU_A /L, available in 830. At 6 months, we assessed allergic sensitization to any food (egg, cow's milk, peanut, wheat, soy) or inhalant (birch, timothy grass, dog, and cat) allergen by a skin prick test wheal diameter ≥2 mm larger than negative control.

RESULTS

Any sensitization was found in 198 of the 1,994 infants (9.9%), the majority to food allergens (n = 177, 8.9%). Eczema, dry skin, and high TEWL at 3 months increased the risk of sensitization at 6 months; adjusted odds ratios 4.20 (95% CI 2.93-6.04), 2.09 (95% CI 1.51-2.90) and 3.67 (95% CI 2.58-5.22), respectively. Eczema predicted sensitization with 55.6% sensitivity and 68.1% specificity; dry skin with 65.3% sensitivity and 57.3% specificity; and high TEWL with 61.7% sensitivity and 78.1% specificity.

CONCLUSION

Eczema, dry skin, and high TEWL at 3 months predicted allergic sensitization at 6 months of age.

Granzyme B in Epithelial Barrier Dysfunction and Related Skin Diseases

The predominant function of the skin is to serve as a barrier - to protect against external insults and to prevent water loss. Junctional and structural proteins in the stratum corneum, the outermost layer of the epidermis, are critical to the integrity of the epidermal barrier as it balances ongoing outward migration, differentiation, and desquamation of keratinocytes in the epidermis. As such, epidermal barrier function is highly susceptible to upsurges of proteolytic activity in the stratum corneum and epidermis. Granzyme B is a serine protease scarce in healthy tissues but present at high levels in tissues encumbered by chronic inflammation. Discovered in the 1980s, Granzyme B is currently recognized for its intracellular roles in immune cell-mediated targeted apoptosis as well as extracellular roles in inflammation, chronic injuries, tissue remodeling, and processing of cytokines, matrix proteins, and autoantigens. Increasing evidence has emerged in recent years supporting a role for Granzyme B in promoting barrier dysfunction in the epidermis by direct cleavage of barrier proteins and eliciting immunoreactivity. Likewise, Granzyme B contributes to impaired epithelial function of the airways, retina, gut and vessels. In the present review, the role of Granzyme B in cutaneous epithelial dysfunction is discussed in the context of specific conditions with an overview of underlying mechanisms as well as utility of current experimental and therapeutic inhibitors.

Association of heat shock protein 8 with atopic march in a murine experimental model

Background

Atopic march (AM), a unique characteristic of allergic diseases, refers to the sequential progression of atopic dermatitis (AD) in infants to allergic asthma and allergic rhinitis in children and young adults, respectively. Although there are several studies on AM, the establishment of an AM murine model to expand our understanding of the underlying mechanism and to identify the potential biomarkers is yet to be achieved. In this study, an improved murine model was established by applying a method to minimize skin irritation in inducing AD, and it was used to perform integrated analyses to discover candidate biomarkers.

Methods

To induce atopic dermatitis, 2,4-dinitrochlorobenzene (DNCB) was applied to the ear skin once a week, and this was continued for 5 weeks. From the second application of DNCB, Dermatophagoides pteronyssinus (Dp) extract was applied topically 2 days after each DNCB application; this was continued for 4 weeks. Dp sensitization and intranasal challenges were then performed for 4 weeks to develop conditions mimicking AM.

Results

Exacerbated airway inflammation and allergic responses observed in the AM-induced group suggested successful AM development in our model. Two-dimensional gel electrophoresis (2-DE) and mass spectrometry analysis identified 753 candidate proteins from 124 2-DE spots differentially expressed among the experimental groups. Functional analyses, such as Gene Ontology (GO) annotation and protein-protein interaction (PPI) analysis were conducted to investigate the relationship among the candidate proteins. Seventy-two GO terms were significant between the two groups; heat shock protein 8 (Hspa8) was found to be included in six of the top 10 GO terms. Hspa8 scored high on the PPI parameters as well.

Conclusion

We established an improved murine model for AM and proposed Hspa8 as a candidate biomarker for AM.

New Directions in Understanding Atopic March Starting from Atopic Dermatitis

Recent evidence showed that the postulated linear progression of the atopic march, from atopic dermatitis to food and respiratory allergies, does not capture the heterogeneity of allergic phenotypes, which are influenced by complex interactions between environmental, genetic, and psychosocial factors. Indeed, multiple atopic trajectories are possible in addition to the classic atopic march. Nevertheless, atopic dermatitis is often the first manifestation of an atopic march. Improved understanding of atopic dermatitis pathogenesis is warranted as this could represent a turning point in the prevention of atopic march. In this review, we outline the recent findings on the pathogenetic mechanisms leading to atopic dermatitis that could be targeted by intervention strategies for the prevention of atopic march.

The role of genetics in food allergy

INTRODUCTION

As the prevalence of food allergies (FA) increases worldwide, our understanding of its pathophysiology and risk factors is markedly expanding. In the past decades, an increasing number of genes have been linked to FA. Identification of such genes may help in predicting the genetic risk for FA development, age of onset, clinical manifestation, causative allergen(s), and possibly the optimal treatment strategies. Furthermore, identification of these genetic factors can help to understand the complex interactions between genes and the environment in predisposition to FA.

AREAS COVERED

We outline the recent important progress in determining genetic variants and disease-associated genes in IgE-mediated FA. We focused on the monogenic inborn errors of immunity (IEI) where FA is one of the clinical manifestations, emphasizing the genes and gene variants which were linked to FA with some of the most robust evidence.

EXPERT OPINION

Genetics play a significant role, either directly or along with environmental factors, in the development of FA. Since FA is a multifactorial disease, it is expected that multiple genes and genetic loci contribute to the risk for its development. Identification of the involved genes should contribute to the area of FA regarding pathogenesis, prediction, recognition, prognosis, prevention, and possibly therapeutic interventions.

Clinical Characteristics of Atopic Dermatitis in Korean School-Aged Children and Adolescents According to Onset Age and Severity

BACKGROUND

Atopic dermatitis (AD) is a heterogeneous disease with different age of onset, disease course, clinical symptoms, severity, and risk of comorbidity. The characteristics of children with AD also vary by age or country. However, little is known about the clinical characteristics of AD in Korean school-aged children and adolescents. Furthermore, there are few studies on phenotypic differences according to onset age. This study aimed to explore the clinical characteristics and phenotypes according to onset age and severity of AD in children and adolescents in Korea.

METHODS

AD patients aged 6-18 years who presented to 18 hospitals nationwide were surveyed. The patients were examined for disease severity by pediatric allergy specialists, and data on history of other allergic diseases, familial allergy history, onset age, trigger factors, lesion sites, treatment history and quality of life were collected. The results of the patient's allergy test were also analyzed. The patients were classified into infancy-onset (< 2 years of age), preschool-onset (2-5 years of age), and childhood-onset (≥ 6 years of age) groups. Study population was analyzed for clinical features according to onset-age groups and severity groups.

RESULTS

A total of 258 patients with a mean age of 10.62 ± 3.18 years were included in the study. Infancy-onset group accounted for about 60% of all patients and presented significantly more other allergic diseases, such as allergic rhinitis and asthma (P = 0.002 and P = 0.001, respectively). Food allergy symptoms and diagnoses were highly relevant to both earlier onset and more severe group. Inhalant allergen sensitization was significantly associated with both infancy-onset group and severe group (P = 0.012 and P = 0.024, respectively). A family history of food allergies was significantly associated with infancy-onset group (P = 0.036). Severe group was significantly associated with a family history of AD, especially a paternal history of AD (P = 0.048 and P = 0.004, respectively). Facial (periorbital, ear, and cheek) lesions, periauricular fissures, hand/foot eczema, and xerosis were associated with infancy-onset group. The earlier the onset of AD, the poorer the quality of life (P = 0.038). Systemic immunosuppressants were used in only 9.6% of the patients in the severe group.

CONCLUSION

This study analyzed the clinical features of AD in Korean children and adolescents through a multicenter nationwide study and demonstrated the phenotypic differences according to onset age and severity. Considering the findings that the early-onset group is more severe and accompanied by more systemic allergic diseases, early management should be emphasized in young children and infants.

Early-life cytomegalovirus infection is associated with gut microbiota perturbations and increased risk of atopy

BACKGROUND

The "old friends" hypothesis posits that reduced exposure to previously ubiquitous microorganisms is one factor involved in the increased rates of allergic diseases. Cytomegalovirus (CMV) may be one of the "old friends" hypothesized to help prevent allergic diseases. We sought to elucidate whether early-life CMV infection is associated with childhood atopy via perturbations of the gut microbiota.

METHODS

Participants were recruited from a population-based birth cohort (CHILD study) and followed prospectively until age 5 years in four Canadian cities. A total of 928 participants provided stool microbiome data, urine for CMV testing, skin prick tests, and questionnaire-based detailed environmental exposures. Cytomegalovirus infection was assessed in the first year of life while the main outcome was defined by persistent sensitization to any allergen at ages 1, 3, and 5 years.

RESULTS

Early CMV infection was associated with increased beta and decreased alpha diversity of the gut microbiota. Both changes in diversity measures and early CMV infection were associated with persistent allergic sensitization at age 5 years (aOR = 2.08; 95% CI: 1, 4.33). Mediation analysis demonstrated that perturbation of gut microbial composition explains 30% of the association.

CONCLUSIONS

Early-life CMV infection is associated with an alteration in the intestinal microbiota, which mediates the effect of the infection on childhood atopy. This work indicates that preventing CMV infection would not put children at increased risk of developing atopy. Rather, a CMV vaccine, in addition to preventing CMV-associated morbidity and mortality, might reduce the risk of childhood allergic diseases.

Sex-specific associations among infant food and atopic sensitizations and infant neurodevelopment

INTRODUCTION

Food sensitization is a first and strong indicator of immune deviation in the progression to other allergic conditions. Sensitization to food or other allergens and related inflammation during critical windows of infant development may adversely affect neurodevelopmental milestones. However, additional research is needed to test this association further.

METHODS

Associations between atopic (any food or aeroallergen) or food sensitization (specific to egg, soybean, peanut, and milk) at age 1 year and neurodevelopment up to 2 years of age were evaluated in the national CHILD Cohort Study, with a secondary aim examining whether these associations were sex-specific. Food and atopic sensitization were assessed by skin prick tests (SPT) in 1-year-old infants, with neurodevelopment assessed using the cognitive, language, motor, and social-emotional subscales of the Bayley Scales of Infant Development (BSID-III) administered at 1 and 2 years of age.

RESULTS

Atopic sensitization was present among 16.4% of infants, while 13.4% had food sensitizations. Only socioemotional scores reached statistical significance among the four BSID-III domains. Both atopic and food sensitization at 1 year of age was associated with lower social-emotional scores, independent of the infant's ethnicity. These findings were sex-specific and only observed among boys, among whom social-emotional scores were lowered by 5 points if atopic sensitization was present (-5.22 [95% CI: -9.96, -0.47], p = 0.03) or if food sensitization was present (-4.85 [95% CI: -9.82,0.11], p = 0.06). Similar results were observed using the standard SPT cut-off of ≥3 mm - for atopic sensitization (-5.17 [95% CI: -11.14, -0.80], p = 0.09) and for food sensitization (-4.61 [95% CI: -10.96, 1.74], p = 0.15).

CONCLUSION

In our study of term infants, we found an inverse, cross-sectional association between atopic and food sensitization status and social-emotional development scores in male children but not female children.

The link between atopic dermatitis and asthma- immunological imbalance and beyond

Atopic diseases are multifactorial chronic disturbances which may evolve one into another and have overlapping pathogenetic mechanisms. Atopic dermatitis is in most cases the first step towards the development of the atopic march and represents a major socio-economic burden in the industrialized countries. The treatment of atopic diseases is often long-lasting and in some cases with lower effectiveness than expected.

In order to prevent the development of the atopic march, the links between the atopic diseases have to be understood. The aim of this review is to present some major points outlining the link between atopic dermatitis and asthma, through a research in the medical literature from recent years.

Stratifying patient populations according to the clinical phenotype of their disease and according to specific measurable values (biomarkers) can help to establish the main etiopathogenetic mechanisms of the disease in these populations. This will add predictive value for the evolution of the disease, and will allow the use and research of more targeted therapy in order to stop this evolution and comorbidities.

Longitudinal atopic dermatitis endotypes: An atopic march paradigm that includes Black children

BACKGROUND

The atopic march has been studied mostly in White populations, biasing our current paradigms.

OBJECTIVE

We sought to define the atopic march in Black and White children and explore mechanisms for racial differences.

METHODS

Utilizing the Mechanisms of Progression of Atopic Dermatitis to Asthma in Children (MPAACH) cohort (n = 601), we assessed longitudinal sensitization, food allergy (FA), allergic rhinitis, risk of asthma development (through the Pediatric Asthma Risk Score), Scoring for Atopic Dermatitis (SCORAD), transepidermal water loss, skin filaggrin (FLG) expression, exposures, and genetic heritability to define AD progression endotypes in Black and White children.

RESULTS

White MPAACH children were more likely to be sensitized to aero and food allergens (P = .0001) and over 3 times more likely to develop FA and/or allergic rhinitis (AR) without asthma risk (P < .0001). In contrast, Black children were over 6 times more likely to proceed to high asthma risk without FA, sensitization, or AR (P < .0001). White children had higher lesional and nonlesional transepidermal water loss (both P < .001) as well as decreased nonlesional keratinocyte FLG expression (P = .02). Black children had increased genetic heritability for asthma risk and higher rates of exposures to secondhand smoke and traffic-related air pollution.

CONCLUSIONS

Black and White children with AD have distinct allergic trajectories defined by different longitudinal endotypes. Black children exhibit higher asthma risk despite a more intact skin barrier and less sensitization, FA, and AR. White children have less asthma risk, despite a more dysfunctional skin barrier, and more FA, AR, and sensitization. The observed racial differences are likely due in part to increased genetic heritability for asthma risk and harmful environmental exposures in Black children. Collectively, our findings provide a new paradigm for an atopic march that is inclusive of Black children.

Atopic Manifestations in Children Born Preterm: A Long-Term Observational Study

(1) Background: Preterm birth exposes the infant to the known risk factors for atopic diseases. We aimed to study the neonatal risk factors and to describe the clinical manifestations of atopy, including the march of symptoms, in a cohort of preschool children born preterm. (2) Methods: We enrolled neonates with gestational age < 32 weeks or birth weight < 1500 g. We classified patients in cases and controls according to the presence of at least one atopic manifestation. (3) Results: We observed 72 cases and 93 controls. Multivariate models showed that the administration of more than one cycle of antibiotics (B 0.902, p = 0.026) and gestational diabetes (B 1.207, p = 0.035) influence the risk of atopy in babies born preterm. In addition, risk of atopic dermatitis was influenced by gestational age < 29 weeks (B -1.710, p = 0.025) and gestational diabetes (B 1.275, p = 0.027). The risk of wheeze was associated with familiarity for asthma (B 1.392, p = 0.022) and the administration of more than one cycle of antibiotics (B 0.969, p = 0.025). We observed a significant reduction in the rate of atopic manifestation after 2 years of life (33.9% vs. 23.8%, p < 0.05). (4) Conclusions: Modifiable (gestational diabetes, antibiotics use) and unmodifiable (familiarity for asthma) conditions influence the risk of atopy in babies born preterm. Extreme prematurity reduces the risk of atopic dermatitis. Preterm babies showed a peculiar atopic march.

Atopy: A Collection of Comorbid Conditions

The concept of atopy was initially developed in the first quarter of the 20th century on the basis of clinical observations without any knowledge of pathogenic mechanisms. Atopy involves a collection of comorbidities that share pathogenic features, and atopic comorbidities affect outcomes of concomitant conditions rather than existing synchronously. The clinical importance of understanding the relationship of these conditions is necessary because the treatment of one condition influences the others, and the development of one leads to or precedes the development of another. Environmental influences and multigenetic predispositions result in complex relationships among the atopic conditions sharing a type 2 pathogenesis. The specialty of Allergy and Immunology is devoted to managing the comorbidities of atopy, and better understanding of their connections can improve patient care.

A comparison of case definitions for infant atopic dermatitis in a multicenter prospective cohort study

This study identified two infant AD case definitions that were strongly associated with known AD risk factors. These case definitions can be used to study novel AD risk factors in large cohort studies, potentially providing new insights into the epidemiology of infant AD.

One march, many paths: Insights into allergic march trajectories

OBJECTIVE

The classical allergic march model posits that atopy begins in infancy with atopic dermatitis and progresses to asthma and allergic rhinitis in a subset of individuals. The growing prevalence and severity of allergic diseases have prompted renewed interest in refining this model. This review outlines epidemiologic evidence for the existence of allergic march trajectories (distinct paths of atopy development in individuals); reviews the roles that genetics, environment, and disease endotypes play in determining trajectory outcomes; and discusses the clinical utility of the trajectory model.

DATA SOURCES

PubMed search of English-language articles and reviews without date limits pertaining to the epidemiology, genetics, and immunologic mechanisms of allergic march trajectories and disease endotypes.

STUDY SELECTIONS

Studies and reviews were selected based on their high quality and direct relevance to the review topic.

RESULTS

Recent work in the field has revealed that immunoglobulin E-mediated food allergy and eosinophilic esophagitis are components of the allergic march. Furthermore, the field is acknowledging that variability exists in the number and sequence of allergic manifestations that individuals develop. These allergic march pathways, or trajectories, are influenced by genetic, environmental, and psychosocial factors that are incompletely understood.

CONCLUSION

Continued elucidation of the landscape and origins of allergic march trajectories will inform efforts to personalize allergic disease prevention, diagnosis, and treatment.

Phenotypes of atopic dermatitis and the risk for subsequent asthma: a systematic review and meta-analysis

BACKGROUND

Various atopic dermatitis (AD) phenotypes showed an enormously heterogenic risk for subsequent asthma development.

OBJECTIVE

We aimed to investigate the association between AD phenotypes and the risk for progression to asthma.

METHODS

We searched PubMed, Embase, and Web of Science databases for relevant publications. Pooled relative risks (RR) with 95% confidence intervals (CI) were calculated using the CMA-3.0 software. This study has been registered with PROSPERO (CRD42019129273).

RESULTS

We analyzed 39 publications with 458,810 participants. The RR for asthma in AD was 2.16 (95% CI, 1.88-2.48). The risk in persistent AD (RR, 3.36; 95% CI, 2.83-3.99) was higher than in transient AD (RR, 1.52; 95% CI, 1.34-1.73), and in severe AD (RR, 2.40; 95% CI, 1.96-2.94) was higher than mild (RR, 1.82; 95% CI, 1.03-3.23) or moderate (RR, 1.51; 95% CI, 1.30-1.75) AD. The risk for asthma in early-onset AD was slightly higher than in late-onset AD and in boys higher than girls.

LIMITATIONS

The AD and asthma definitions differed across the included studies.

CONCLUSION

Patients with persistent or severe AD were at a higher risk for developing asthma. These findings further elucidate the atopic march and identify target populations for asthma prevention.