Sensitization to peanut, egg or pets is associated with skin barrier dysfunction in children with atopic dermatitis

Skin Barrier in Normal and Allergic Horses: What Do We Know?

Information on skin barrier in horses is limited. A study on the epidermal ultrastructure of normal and allergic horses documented disorganized amorphous intercellular lipids in the stratum corneum of allergic samples. These findings are similar to atopic canine and human skin. Currently, there is no published study comparing skin barrier function parameters between normal and allergic horses; thus, the functional implications of the ultrastructural changes are unknown. In normal horses, body location, gender, breed, and ambient conditions affect skin barrier parameters, such as Transepidermal Water Loss. Skin microbiome studies on normal horses have highlighted the importance of season and environmental conditions, since horses housed together share similar microbiomes. Skin dysbiosis and predominance of staphylococcus have been described in horses with pastern dermatitis. Transcriptomic studies of the epidermis of normal and allergic horses have found that lesional allergic skin has substantial transcriptomic differences when compared with healthy skin, namely downregulation of genes of tight junctions, keratins, and upregulation of serine proteases and IL-13. Keratinocytes harvested from horses with insect bite hypersensitivity show upregulation of IL-31 gene expression under stimulation. While more research is clearly needed, preliminary results seem to support skin barrier differences between normal and allergic horses.

Progressive accumulation of hyperinflammatory NKG2Dlow NK cells in early childhood severe atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that often precedes the development of food allergy, asthma, and allergic rhinitis. The prevailing paradigm holds that a reduced frequency and function of natural killer (NK) cell contributes to AD pathogenesis, yet the underlying mechanisms and contributions of NK cells to allergic comorbidities remain ill-defined. Here, analysis of circulating NK cells in a longitudinal early life cohort of children with AD revealed a progressive accumulation of NK cells with low expression of the activating receptor NKG2D, which was linked to more severe AD and sensitivity to allergens. This was most notable in children co-sensitized to food and aeroallergens, a risk factor for development of asthma. Individual-level longitudinal analysis in a subset of children revealed coincident reduction of NKG2D on NK cells with acquired or persistent sensitization, and this was associated with impaired skin barrier function assessed by transepidermal water loss. Low expression of NKG2D on NK cells was paradoxically associated with depressed cytolytic function but exaggerated release of the proinflammatory cytokine tumor necrosis factor-α. These observations provide important insights into a potential mechanism underlying the development of allergic comorbidity in early life in children with AD, which involves altered NK cell functional responses, and define an endotype of severe AD.

Dog Allergy in Children: A Single-Centered Study

INTRODUCTION

Dogs are among the most commonly allergenic pets for children. Data on risk factors for the development of dog allergy are scarce. This study aimed to evaluate the characteristics of children with dog allergy and identify predictors of symptom development with dog exposure.

METHODS

The study included children with dog allergen sensitization demonstrated by skin prick test (SPT) between September 1, 2019, and December 1, 2022. Demographic, clinical, and laboratory data were collected from the patients' records and interviews with parents.

RESULTS

Dog allergen sensitization was detected by SPT in 548 (5.5%) of 9,907 patients. Of these, 507 patients had complete data and were included in the analysis. The patients' median age was 11 (IQR: 8-15) years, 55.8% were male, 97.6% exhibited polysensitization (pollen 75.1%, cat 69.6%), 83.6% had allergic rhinitis, and 46.2% had asthma. Acute dog exposure caused symptoms in 164 patients (32.3%), most commonly sneezing (n = 97) and nasal symptoms (n = 80). Predictors of acute symptoms in dog-sensitized children were male sex (OR: 0.584 [CI: 0.38-0.87]), dog exposure before 1 year of age (OR: 2.35 [CI: 1.18-4.66]), close contact with a dog owner (OR: 2.93 [CI: 1.78-4.8]), and cat allergy (OR: 2.75 [CI: 1.82-4.1]).

CONCLUSION

Approximately one-third of children with dog sensitization developed symptoms after exposure to the dog. Male sex, direct dog exposure before the age of one, close contact with a dog owner, and cat allergy were identified as predictors of dog allergy.

Constant vigilance! Managing threats to the skin barrier

OBJECTIVE

Skin barrier defects are one of the primary causes of atopic dermatitis (AD). The basis of skin barrier defects in AD is due to a deficiency in various barrier proteins including filaggrin, involucrin, claudins, and lipids such as ceramide, fatty acids, and cholesterol. This review updates a more detailed lipid dysregulation in the skin barrier of AD based on recent lipidomic analysis. The clinical implications, treatments, prevention, and predictive capability of skin barrier defects are also reviewed.

DATA SOURCES

Published literature obtained through PubMed searches.

STUDY SELECTIONS

Studies relevant to the mechanisms, clinical implications, treatments, prevention, and predictors of AD development.

RESULTS

Skin barrier defects contribute to transepidermal water loss, infections, IgE sensitizations, and cutaneous inflammation in AD. Preventive treatments include daily hydration and application of moisturizers. Because skin barrier defects precede the development of AD, they provide an opportunity for prediction and intervention.

CONCLUSION

Skin barrier defects play an important role in the comorbidities of AD including infectious complications, disease flare, and allergic diathesis. Current research focuses on prevention and prediction of AD development.

Electrical impedance spectroscopy detects skin barrier dysfunction in childhood atopic dermatitis

BACKGROUND

Skin barrier dysfunction is associated with the development of atopic dermatitis (AD), however methods to assess skin barrier function are limited. We investigated the use of electrical impedance spectroscopy (EIS) to detect skin barrier dysfunction in children with AD of the CARE (Childhood AlleRgy, nutrition, and Environment) cohort.

METHODS

EIS measurements taken at multiple time points from 4 months to 3-year-old children, who developed AD (n = 66) and those who did not (n = 49) were investigated. Using only the EIS measurement and the AD status, we developed a machine learning algorithm that produces a score (EIS/AD score) which reflects the probability that a given measurement is from a child with active AD. We investigated the diagnostic ability of this score and its association with clinical characteristics and age.

RESULTS

Based on the EIS/AD score, the EIS algorithm was able to clearly discriminate between healthy skin and clinically unaffected skin of children with active AD (area under the curve 0.92, 95% CI 0.85-0.99). It was also able to detect a difference between healthy skin and AD skin when the child did not have active AD. There was no clear association between the EIS/AD score and the severity of AD or sensitisation to the tested allergens. The performance of the algorithm was not affected by age.

CONCLUSIONS

This study shows that EIS can detect skin barrier dysfunction and differentiate skin of children with AD from healthy skin and suggests that EIS may have the ability to predict future AD development.

Prediction of Food Sensitization in Children with Atopic Dermatitis Based on Disease Severity and Epidermal Layer Impairment

INTRODUCTION

Atopic dermatitis (AD) is characterized by an impaired epidermal barrier, which could be associated with sensitization to food allergens (FAs) and/or inhaled allergens and contribute to the severity of AD. However, no clinical guidance has been established for evaluations of food sensitization (FS) in AD patients. This study investigated how AD severity and epidermal barrier impairment are associated with FS and factors that can predict FS in children with AD.

METHODS

This cross-sectional study included 100 children (12-60 months) diagnosed with AD. AD severity was determined using the Scoring Atopic Dermatitis (SCORAD) index. FS was evaluated by measuring serum-specific IgE antibodies against 31 FAs using an immunoblotting method. Epidermal barrier impairment was assessed by measuring transepidermal water loss (TEWL) and stratum corneum hydration (SCH) levels.

RESULTS

90% of participants were sensitized to at least one tested FA, with cow's milk, egg white, beef, almond, egg yolk, and peanut being the most common. Children with moderate-severe AD had lower SCH levels than those with mild AD. Children with AD who were sensitized to >10 FAs had significantly higher TEWL and lower SCH levels, compared with those sensitized to 1-4 FAs and 5-10 FAs. The SCORAD score and SCH level in lesional skin provided moderately predictive value for sensitization to FAs in children with AD.

CONCLUSION

FS is common in children with AD and closely associate with AD severity as well as epidermal barrier impairment. Evaluations of FS should be considered for children with moderate to severe AD and/or low SCH levels.

Safety of Oral Food Challenge for Individuals with Low Egg White and Ovomucoid-Specific IgE Antibodies

INTRODUCTION

During an oral food challenge (OFC), there is a risk of adverse reactions, including anaphylaxis. Therefore, the physician should carefully conduct the OFC. This study aimed to evaluate the OFC results in individuals with low levels of egg white (EW)- and ovomucoid (OVM)-specific immunoglobulin E (sIgE) and the safety of a hen's egg (HE) OFC in these individuals.

METHODS

A total of 2,058 individuals with low EW- or OVM-sIgE underwent HE-OFC at two institutions in Kumamoto prefecture, located in the western area of Japan, between January 1, 2017, and December 31, 2021, within 1 year of recorded sIgE measurements. The ImmunoCAP systems were used to measure sIgEs. The HE-OFC test was performed according to the 2017 Food Allergy Guidelines in an open and unblinded method.

RESULTS

Five hundred and one individuals (24.3%) had low EW-sIgE levels (class 2 or lower), and 926 (45.0%) had low OVM-sIgE levels (class 2 or lower). Individuals with low EW-sIgE had lower total IgE and OVM-sIgE than did those with high EW-sIgE (greater than class 2). Those with low OVM-sIgE had lower total IgE and EW-sIgE than did those with high OVM-sIgE (greater than class 2). Among the individuals with low EW-sIgE, 86.4% (433/501 cases) passed the OFC without symptoms. Among the individuals with low OVF-sIgE, 82.6% (765/926 cases) passed the OFC without symptoms.

CONCLUSION

More than 80% of individuals with suspected IgE-dependent HE allergy and low levels of EW- or OVM-specific IgE were able to consume at least a small amount of HE. As the OFC results are independent of the loading dose in cases with low EW- or OVM-sIgE, a medium-dose HE-OFC may be performed safely in individuals with no history of anaphylaxis.

Progressive accumulation of hyperinflammatory NKG2D low NK cells in early childhood severe atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that often precedes the development of food allergy, asthma, and allergic rhinitis. The prevailing paradigm holds that a reduced frequency and function of natural killer (NK) cell contributes to AD pathogenesis, yet the underlying mechanisms and contributions of NK cells to allergic co-morbidities remain ill-defined. Herein, analysis of circulating NK cells in a longitudinal early life cohort of children with AD revealed a progressive accumulation of NK cells with low expression of the activating receptor NKG2D, which was linked to more severe AD and sensitivity to allergens. This was most notable in children co-sensitized to food and aero allergens, a risk factor for development of asthma. Individual-level longitudinal analysis in a subset of children revealed co-incident reduction of NKG2D on NK cells with acquired or persistent sensitization, and this was associated with impaired skin barrier function assessed by transepidermal water loss. Low expression of NKG2D on NK cells was paradoxically associated with depressed cytolytic function but exaggerated release of the proinflammatory cytokine TNF-α. These observations provide important insights into a potential mechanism underlying the development of allergic co-morbidity in early life in children with AD which involves altered NK-cell functional responses, and define an endotype of severe AD.

The Primary Prevention of Atopy: Does Early Exposure to Cats and Dogs Prevent the Development of Allergy and Asthma in Children? A Comprehensive Analysis of the Literature

The current literature shows mixed results relating to the significance of environmental exposure, such as owning a pet, and the development of atopy in children. Our review aimed to collect the most recent evidence on the association between early-life cat and dog ownership and the development of allergy and asthma. A comprehensive literature review was performed using PubMed and Scopus. The search included the main keywords of our PICO: (((early exposure) AND (children) AND (allergy)) OR (asthma)) AND (dog) OR (cat). Randomized controlled trials (RCTs), case-control studies, clinical trials, meta-analyses, and systematic reviews of children within the last five years (2018-2023) were searched and included. During the search process, 52 articles from PubMed and 43 from Scopus were found. A total of 17 articles were deemed to be suitable and included. Fairly consistent results regarding early exposure to pets, in particular dogs, and the prevention of food allergies have been described. Furthermore, there seems to be a protective effect against allergy and asthma in relation to the number of pets owned. The likelihood of a child developing allergy and asthma seems to be influenced by various factors, including the child's genetic background and early exposure to different environmental factors, including allergens that may interact with the gut microbiota and immune system.

Practical Approach to Hypersensitivity to Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) in Children

BACKGROUND

We aimed to assess the real-life prevalence, patient profile, and clinical presentation of drug hypersensitivity to NSAIDs in children after an incidence of an adverse event during treatment, verified by a drug challenge test.

METHODS

We included 56 children, aged 4-18 years, referred to our allergy clinic due to the incidence of adverse reaction during treatment. Skin prick tests and a drug provocation test were performed in all patients. Diagnostics for persistent urticaria were performed.

RESULTS

In 56 patients suspected of drug allergy, we proved NSAID hypersensitivity in 17 patients (30.1%). In 84.9% (n = 47) of patients, the clinical manifestations of hypersensitivity revealed angioedema and urticaria. The most common culprit drug among NSAIDs in children was ibuprofen. Thirty-one (55.4%) reactions were immediate, and 25 (44.6%) were delayed or late. Previous history of allergy was a risk factor for NSAID hypersensitivity (p = 0.001). Vitamin D deficiency in the blood serum was a risk factor for NASID hypersensitivity (OR = 5.76 (95% Cl: 1.42-23.41)).

CONCLUSIONS

Hypersensitivity to NSAIDs is a difficult diagnostic problem in pediatric allergy. The most common manifestation of hypersensitivity to ibuprofen in children is acute urticaria and angioedema. Two important problems in the differential diagnosis are cofactors such as vitamin D levels and viral infections, which require further research.

Epicutaneous Sensitization and Food Allergy: Preventive Strategies Targeting Skin Barrier Repair-Facts and Challenges

Food allergy represents a growing public health and socio-economic problem with an increasing prevalence over the last two decades. Despite its substantial impact on the quality of life, current treatment options for food allergy are limited to strict allergen avoidance and emergency management, creating an urgent need for effective preventive strategies. Advances in the understanding of the food allergy pathogenesis allow to develop more precise approaches targeting specific pathophysiological pathways. Recently, the skin has become an important target for food allergy prevention strategies, as it has been hypothesized that allergen exposure through the impaired skin barrier might induce an immune response resulting in subsequent development of food allergy. This review aims to discuss current evidence supporting this complex interplay between the skin barrier dysfunction and food allergy by highlighting the crucial role of epicutaneous sensitization in the causality pathway leading to food allergen sensitization and progression to clinical food allergy. We also summarize recently studied prophylactic and therapeutic interventions targeting the skin barrier repair as an emerging food allergy prevention strategy and discuss current evidence controversies and future challenges. Further studies are needed before these promising strategies can be routinely implemented as prevention advice for the general population.

Elevated serum total IgE is associated with eczema exacerbation in children hospitalized for atopic dermatitis

BACKGROUND/OBJECTIVES

Atopic dermatitis (AD) can be a debilitating skin condition, often leading to hospitalization due to severe AD exacerbations or infectious complications. As both AD exacerbations and infectious complications can present similarly, it can be difficult to distinguish the two conditions. Thus, we aimed to evaluate if there is any difference in serum IgE levels in children with AD who were hospitalized for AD exacerbation and for AD-associated infectious complications.

METHODS

A retrospective chart review was performed on hospitalized children with AD exacerbations and AD-associated infectious complications over a 17-year span. Data including length of stay, primary diagnosis, systemic antibiotics, laboratory, and bacterial culture results were collected. Serum total immunoglobulin E (IgE) levels were adjusted by age. Age, length of stay, total IgE levels, and age-adjusted IgE levels were compared using t-test. Logistic regression was used for age-adjusted IgE levels.

RESULTS

The mean serum total IgE level in subjects with AD exacerbation was 9603 ± 15,873 kU/L, which was significantly higher than that of subjects with infectious complications at 3167 ± 5486 kU/L (p = .029). Logistic regression revealed that subjects with an age-adjusted IgE of >4 had more than 3-fold odds of having AD exacerbation than infectious complications.

CONCLUSIONS

Our results suggest that total IgE levels are higher in children who were hospitalized for AD exacerbation than those with AD-associated infectious complications.

Food allergy, mechanisms, diagnosis and treatment: Innovation through a multi-targeted approach

The incidence of food allergy (FA) has continued to rise over the last several decades, posing significant burdens on health and quality of life. Significant strides into the advancement of FA diagnosis, prevention, and treatment have been made in recent years. In an effort to lower reliance on resource-intensive food challenges, the field has continued work toward the development of highly sensitive and specific assays capable of high-throughput analysis to assist in the diagnosis FA. In looking toward early infancy as a critical period in the development of allergy or acquisition of tolerance, evidence has increasingly suggested that early intervention via the early introduction of food allergens and maintenance of skin barrier function may decrease the risk of FA. As such, large-scale investigations are underway evaluating infant feeding and the impact of emollient and steroid use in infants with dry skin for the prevention of allergy. On the other end of the spectrum, the past few years have been witness to an explosive increase in clinical trials of novel and innovative therapeutic strategies aimed at the treatment of FA in those whom the disease has already manifested. A milestone in the field, 2020 marked the approval of the first drug, oral peanut allergen, for the indication of peanut allergy. With a foundation of promising data supporting the safety and efficacy of single- and multi-allergen oral immunotherapy, current efforts have turned toward the use of probiotics, biologic agents, and modified allergens to optimize and improve upon existing paradigms. Through these advancements, the field hopes to gain footing in the ongoing battle against FA.

Vitamin D, skin filaggrin, allergic sensitization, and race

BACKGROUND

In addition to its involvement in both the innate and adaptive immune systems, vitamin D has been found to affect keratinocyte function and proliferation, suggesting a possible role for vitamin D in cutaneous allergic sensitization.

OBJECTIVE

To explore the role of circulating vitamin D levels in allergic sensitization.

METHODS

Serum 25-hydroxyvitamin D (25(OH)D) levels were measured in a subset of children (N = 323) enrolled in the Mechanisms of Progression of Atopic Dermatitis to Asthma in Children cohort, a prospective early life cohort of children with atopic dermatitis. Allergic sensitization was determined using skin prick testing, and FLG expression in the keratinocytes was measured by quantitative polymerase chain reaction. Multiple Poisson regression was used to evaluate interaction effects between serum 25(OH)D levels and FLG expression with sensitization load as the outcome.

RESULTS

Black participants had significantly lower mean levels of serum 25(OH)D compared with non-Black participants (29.3 vs 32.9 ng/mL; P < .001). FLG expression and sensitization load were negatively correlated in non-Black participants with 25(OH)D levels less than 27.2 ng/mL (Rho = -0.45; P = .02). No association between FLG expression and sensitization load was found in Black participants or participants with 25(OH)D levels greater than or equal to 27.2 ng/mL. Multiple Poisson regression models confirmed that 25(OH)D levels interact with FLG expression to affect sensitization load in non-Black participants.

CONCLUSION

Despite lower vitamin D levels in Black participants, sensitization load was associated with nonlesional skin FLG expression in non-Black, but not Black, children with low vitamin D levels. Thus, a complex interplay of factors determines the impact of vitamin D on allergic sensitization.

Skin barrier defects in atopic dermatitis: From old idea to new opportunity

Atopic dermatitis (AD) is the most common chronic skin inflammatory disease, with a profound impact on patients’ quality of life. AD varies considerably in clinical course, age of onset and degree to which it is accompanied by allergic and non-allergic comorbidities. Skin barrier impairment in both lesional and nonlesional skin is now recognized as a critical and often early feature of AD. This may be explained by a number of abnormalities identified within both the stratum corneum and stratum granulosum layers of the epidermis. The goal of this review is to provide an overview of key barrier defects in AD, starting with a historical perspective. We will also highlight some of the commonly used methods to characterize and quantify skin barrier function. There is ample opportunity for further investigative work which we call out throughout this review. These include: quantifying the relative impact of individual epidermal abnormalities and putting this in a more holistic view with physiological measures of barrier function, as well as determining whether these barrier-specific endotypes predict clinical phenotypes (e.g. age of onset, natural history, comorbidities, response to therapies, etc). Mechanistic studies with new (and in development) AD therapies that specifically target immune pathways, Staphylococcus aureus abundance and/or skin barrier will help us understand the dynamic crosstalk between these compartments and their relative importance in AD.