Identification of atopic dermatitis subgroups in children from 2 longitudinal birth cohorts

Predicting Skin Barrier Dysfunction and Atopic Dermatitis in Early Infancy

BACKGROUND

Dry skin is associated with increased transepidermal water loss (TEWL), which has been found to precede atopic dermatitis (AD) in childhood.

OBJECTIVE

We aimed to identify parental, prenatal, and perinatal predictive factors of dry skin, high TEWL, and AD at 3 months of age, and to determine if dry skin or high TEWL at 3 months can predict AD at 6 months.

METHODS

From the Preventing Atopic Dermatitis and Allergies in children prospective birth cohort study, we included 1150 mother-child pairs. Dry skin, TEWL, and eczema were assessed at 3- and 6-month investigations. Eczema, used as a proxy for AD, was defined as the presence of eczematous lesions, excluding differential diagnoses to AD. High TEWL was defined as TEWL >90th percentile, equaling 11.3 g/m²/h. Potential predictive factors were recorded from electronic questionnaires at 18- and 34-week pregnancy and obstetric charts.

RESULTS

Significant predictive factors (P < .05) for dry skin at 3 months were delivery >38 gestational weeks and paternal age >37 years; for high TEWL, male sex, birth during winter season, and maternal allergic disease; and for eczema, elective caesarean section, multiparity, and maternal allergic diseases. Dry skin without eczema at 3 months was predictive for eczema at 6 months (adjusted odds ratio: 1.92, 95% confidence interval: 1.21-3.05; P = .005), whereas high TEWL at 3 months was not.

CONCLUSION

In early infancy, distinct parental- and pregnancy-related factors were predictive for dry skin, high TEWL, and AD. Dry skin at 3 months of age was predictive for AD 3 months later.

Proteomic analysis of a filaggrin-deficient skin organoid model shows evidence of increased transcriptional-translational activity, keratinocyte-immune crosstalk and disordered axon guidance

Background:Atopic eczema is an itchy inflammatory disorder characterised by skin barrier dysfunction. Loss-of-function mutations in the gene encoding filaggrin (FLG) are a major risk factor, but the mechanisms by which filaggrin haploinsufficiency leads to atopic inflammation remain incompletely understood. Skin as an organ that can be modelled using primary cellsin vitroprovides the opportunity for selected genetic effects to be investigated in detail.Methods:Primary human keratinocytes and donor-matched primary fibroblasts from healthy individuals were used to create skin organoid models with and without siRNA-mediated knockdown ofFLG. Biological replicate sets of organoids were assessed using histological, functional and biochemical measurements.Results:FLGknockdown leads to subtle changes in histology and ultrastructure including a reduction in thickness of the stratum corneum and smaller, less numerous keratohyalin granules. Immature organoids showed evidence of barrier impairment withFLGknockdown, but the mature organoids showed no difference in transepidermal water loss, water content or dye penetration. There was no difference in epidermal ceramide content. Mass spectrometry proteomic analysis detected >8000 proteins per sample. Gene ontology and pathway analyses identified an increase in transcriptional and translational activity but a reduction in proteins contributing to terminal differentiation, including caspase 14, dermokine, AKT1 and TGF-beta-1. Aspects of innate and adaptive immunity were represented in both the up-regulated and down-regulated protein groups, as was the term ‘axon guidance’.     Conclusions:This work provides further evidence for keratinocyte-specific mechanisms contributing to immune and neurological, as well as structural, aspects of skin barrier dysfunction. Individuals with filaggrin deficiency may derive benefit from future therapies targeting keratinocyte-immune crosstalk and neurogenic pruritus.

Role of timing of exposure to pets and dampness or mould on asthma and sensitization in adolescence

BACKGROUND

Pet and dampness or mould exposure are considered risk factors for asthma and sensitization. It is unclear whether timing of exposure to these factors is differentially associated with asthma risk and sensitization in adolescence.

OBJECTIVE

We investigated the role of timing of pet and dampness or mould exposure in asthma and sensitization in adolescence. Understanding this role is essential to build targeted prevention strategies.

METHODS

We used data from 1871 participants of the Dutch Prevention and Incidence of Asthma and Mite Allergy (PIAMA) cohort. Residential exposure to pets, dampness or mould was assessed by repeated parental questionnaires. We used asthma data from the 17-year questionnaire and sensitization data from the 16-year medical examination. We characterized timing using longitudinal exposure patterns from pregnancy till age 17 using longitudinal latent class growth modelling. We used logistic regression models to analyse associations of exposure patterns with asthma at age 17 and sensitization at age 16.

RESULTS

For none of the time windows, exposure to pets and dampness or mould was associated with asthma at age 17, but a lower sensitization risk at age 16 was suggested, for example the odds ratio (95% confidence interval) for sensitization was 0.63 (0.35-1.11) and 0.69 (0.44-1.08) for early life and persistently high pet exposure, respectively, compared with very low exposure. An inverse association was also suggested for sensitization and moderate early childhood dampness or mould exposure (0.71 [0.42-1.19]).

CONCLUSION AND CLINICAL RELEVANCE

Different timing of pet and dampness or mould exposure was not associated with asthma, but lower risk of sensitization in adolescence was suggested, which could be partly attributable to reversed causation. Current findings are not sufficient to recommend pet avoidance to prevent allergic disease. More prospective studies are needed to obtain insights that can be used in clinical practice.

Most associations of early-life environmental exposures and genetic risk factors poorly differentiate between eczema phenotypes: the Generation R Study

Background

Childhood eczema is variable in onset and persistence.

Objectives

To identify eczema phenotypes during childhood, and their associations with early‐life environmental and genetic factors.

Methods

In this study of 5297 children from a multiethnic population‐based prospective cohort study, phenotypes based on parent‐reported physician‐diagnosed eczema from age 6 months to 10 years were identified using latent class growth analysis. Information on environmental factors was obtained using postal questionnaires. Four filaggrin mutations were genotyped and a risk score was calculated based on 30 genetic variants. Weighted adjusted multinomial models were used for association analyses.

Results

We identified the following five eczema phenotypes: never (76%), early transient (8%), mid‐transient (6%) and late transient (8%) and persistent eczema (2%). Early transient and persistent eczema were most common in first‐born children, those with a parental history of eczema, allergy or asthma and those with persistent wheezing [range of odds ratio (OR): 1.37, 95% confidence interval (CI) 1.07–1.74 and OR 3.38, 95%CI 1.95–5.85]. Early transient eczema was most common in male children only (OR 1·49, 95% CI 1·18–1·89). Children with late transient or persistent eczema were more often of Asian ethnicity (OR 2·04, 95% CI 1·14–3·65 and OR 3·08, 95% CI 1·34–7·10, respectively). Children with early, late transient and persistent eczema more often had a filaggrin mutation or additional risk alleles (range OR: 1.07, 95%CI 1.02–1.12 and OR 2.21, 95%CI 1.39–3.50). Eczema phenotypes were not associated with maternal education, breastfeeding, day care attendance and pet exposure.

Conclusions

Five eczema phenotypes were identified in a multiethnic paediatric population with limited differences in risk profiles, except for sex and ethnicity.

What's already known about this topic?

Two previous studies in longitudinal birth cohorts identified four and six different eczema phenotypes, predominantly in children of European ethnicity.

What does this study add?

Five eczema phenotypes were identified in a multiethnic paediatric population using latent class growth analysis.

Children with early transient and persistent eczema were most often first‐born children and had persistent wheezing, filaggrin mutation or additional risk alleles.

Previously known eczema risk factors had limited differentiating capabilities for eczema phenotypes, except for the association of early transient eczema with male children, and late transient and persistent eczema with Asian ethnicity.

https://doi.org/10.1111/bjd.18575 available online

https://www.bjdonline.com/article/most-associations-of-early-life-environmental-exposures-and-genetic-risk-factors-poorly-differentiate-between-eczema-phenotypes-the-generation-r-study/

Understanding the immune landscape in atopic dermatitis: The era of biologics and emerging therapeutic approaches

Atopic dermatitis (AD) is a chronic, systemic, inflammatory disease that affects the skin and is characterized by persistent itch and marked redness. AD is associated with an increased risk of skin infections and a reduced quality of life. Most AD treatment options to date were not designed to selectively target disease-causing pathways that have been established for this indication. Topical therapies have limited efficacy in moderate-to-severe disease, and systemic agents such as corticosteroids and immunosuppressants present with tolerability issues. Advances in the understanding of AD pathobiology have made possible a new generation of more disease-specific AD therapies. AD is characterized by the inappropriate activation of type 2 T helper (Th2) cells and type 2 innate lymphoid (ILC2) cells, with a predominant increase in type 2 cytokines in the skin, including interleukin (IL)-13 and IL-4. Both cytokines are implicated in tissue inflammation and epidermal barrier dysfunction, and monoclonal antibodies targeting each of these interleukins or their receptors are in clinical development in AD. In March 2017, dupilumab, a human anti-IL-4Rα antibody, became the first biologic to receive approval in the United States for the treatment of moderate-to-severe AD. The anti-IL-13 monoclonal antibodies lebrikizumab and tralokinumab, which bind different IL-13 epitopes with potentially different effects, are currently in advanced-stage trials. Here, we briefly review the underlying pathobiology of AD, the scientific basis for current AD targets, and summarize current clinical studies of these agents, including new research to develop both predictive and response biomarkers to further advance AD therapy in the era of precision medicine.

Different definitions of atopic dermatitis: impact on prevalence estimates and associated risk factors

Background

There is no objective test that can unequivocally confirm the diagnosis of atopic dermatitis (AD), and no uniform clinical definition.

Objectives

To investigate to what extent operational definitions of AD cause fluctuation in the prevalence estimates and the associated risk factors.

Methods

We first reviewed the operational definitions of AD used in the literature. We then tested the impact of the choice of the most common definitions of ‘cases’ and ‘controls’ on AD prevalence estimates and associated risk factors (including filaggrin mutations) among children aged 5 years in two population‐based birth cohorts: the Manchester Asthma and Allergy Study (MAAS) and Asthma in Ashford. Model performance was measured by the percentage of children within an area of clinical indecision (defined as having a posterior probability of AD between 25% and 60%).

Results

We identified 59 different definitions of AD across 45 reviewed studies. Of those, we chose four common ‘case’ definitions and two definitions of ‘controls’. The prevalence estimates using different case definitions ranged between 22% and 33% in MAAS, and between 12% and 22% in Ashford. The area of clinical indecision ranged from 32% to 44% in MAAS and from 9% to 29% in Ashford. Depending on the case definition used, the associations with filaggrin mutations varied, with odds ratios (95% confidence intervals) ranging from 1·8 (1·1–2·9) to 2·2 (1·3–3·7) in MAAS and 1·7 (0·8–3·7) to 2·3 (1·2–4·5) in Ashford. Associations with filaggrin mutations also differed when using the same ‘case’ definition but different definitions of ‘controls’.

Conclusions

Use of different definitions of AD results in substantial differences in prevalence estimates, the performance of prediction models and association with risk factors.

What's already known about this topic?

There is no objective test that can unequivocally confirm the diagnosis of atopic dermatitis (AD) and no uniform clinical definition.

This results in different definitions utilized in AD studies, raising concerns on the generalizability of the results and comparability across different studies.

What does this study add?

This study has shown that different definitions of ‘cases’ and ‘controls’ have major impacts upon prevalence estimates and associations with risk factors, including genetics, in two population‐based birth cohorts.

These findings suggest the importance of developing a consensus on AD definitions of both ‘controls’ and ‘cases’ to minimize biases in studies.

https://www.bjdonline.com/article/different-definitions-of-atopic-dermatitis-impact-on-prevalence-estimates-and-associated-risk-factors/

Linked Comment: https://doi.org/10.1111/bjd.18303.

https://doi.org/10.1111/bjd.18571 available online

Genetics of Atopic Dermatitis: From DNA Sequence to Clinical Relevance

Atopic dermatitis (AD) is a complex disease that is thought to be triggered by environmental factors in genetically susceptible individuals. Twin studies have estimated the heritability of AD to be approximately 75%, with the null (loss-of-function) mutations of the gene encoding filaggrin (FLG) (chromosome 1q21.3) as the strongest known genetic risk factor. The discovery of the filaggrin gene was important in the emerging model for AD pathogenesis, combining skin barrier function with adaptive and innate immunity. Assisted by the recent development of large-scale high-throughput genomics, more than 30 genetic loci have been linked to AD across different populations. Identification of these loci, together with functional studies, has already provided new insights into disease biology and identified novel drug targets. Further, these susceptibility loci are laying the groundwork for phenome-wide association studies to test their multiple phenotype relationships and application of Mendelian randomization to investigate causal relationships. Despite many known genes, a majority of the genetic risk for AD is yet unexplored. Therefore, studies investigating refined phenotype groups, low-frequency and rare genetic variation, gene-gene and/or gene-environment interactions, epigenetic mechanisms and data from multi-omics technologies are warranted. In this review, we describe genetic discoveries for AD, including results from candidate gene studies, studies of AD-like genetic diseases, genome-wide association studies and genetic sequencing studies. We explain how some of these genetic discoveries have unraveled new mechanistic insights into the pathogenesis of AD and exemplify how personal genetic data could be used for preventive strategies and a tailored treatment regimen (i.e., precision medicine).

EMSY expression affects multiple components of the skin barrier with relevance to atopic dermatitis

Background

Atopic dermatitis (AD) is a common, complex, and highly heritable inflammatory skin disease. Genome-wide association studies offer opportunities to identify molecular targets for drug development. A risk locus on chromosome 11q13.5 lies between 2 candidate genes, EMSY and LRRC32 (leucine-rich repeat-containing 32) but the functional mechanisms affecting risk of AD remain unclear.

Objectives

We sought to apply a combination of genomic and molecular analytic techniques to investigate which genes are responsible for genetic risk at this locus and to define mechanisms contributing to atopic skin disease.

Methods

We used interrogation of available genomic and chromosome conformation data in keratinocytes, small interfering RNA (siRNA)–mediated knockdown in skin organotypic culture and functional assessment of barrier parameters, mass spectrometric global proteomic analysis and quantitative lipid analysis, electron microscopy of organotypic skin, and immunohistochemistry of human skin samples.

Results

Genomic data indicate active promoters in the genome-wide association study locus and upstream of EMSY; EMSY, LRRC32, and intergenic variants all appear to be within a single topologically associating domain. siRNA-knockdown of EMSY in organotypic culture leads to enhanced development of barrier function, reflecting increased expression of structural and functional proteins, including filaggrin and filaggrin-2, as well as long-chain ceramides. Conversely, overexpression of EMSY in keratinocytes leads to a reduction in markers of barrier formation. Skin biopsy samples from patients with AD show greater EMSY staining in the nucleus, which is consistent with an increased functional effect of this transcriptional control protein.

Conclusion

Our findings demonstrate an important role for EMSY in transcriptional regulation and skin barrier formation, supporting EMSY inhibition as a therapeutic approach.

Phenotypic analysis of atopic dermatitis in children aged 1-12 months: elaboration of novel diagnostic criteria for infants in China and estimation of prevalence

BACKGROUND

Atopic dermatitis (AD) is the most common skin disorder in infancy. However, the diagnosis and definite significance of infantile AD remains a debated issue.

OBJECTIVE

To analyse the phenotypes of AD in infancy, to establish diagnostic criteria and to estimate the prevalence of this condition in China.

METHODS

This is a multicentric study, in which 12 locations were chosen from different metropolitan areas of China. Following careful and complete history-taking and skin examination, the definite diagnosis of AD was made and the severity based on the SCORAD index was determined by local experienced dermatologists. Based on the detailed phenotyping, the major and representative clinical features of infantile AD were selected to establish the diagnostic criteria and evaluate their diagnostic efficacy.

RESULTS

A total of 5967 infants were included in this study. The overall point prevalence of AD was 30.48%. The infantile AD developed as early as at the second month of life, and its incidence peaked in the third month of life at 40.81%. The proportion of mild, moderate and severe AD was 67.40%, 30.57% and 2.03%, respectively. The most commonly seen manifestations in the infantile AD were facial dermatitis (72.07%), xerosis (42.72%) and scalp dermatitis (27.93%). We established the novel diagnostic criteria of infants, which included: (i) onset after 2 weeks of birth; (ii) pruritus and/or irritability and sleeplessness comparable with lesions; and (iii) all two items above with one of the following items can reach a diagnosis of AD: (i) eczematous lesions distributed on cheeks and/or scalp and/or extensor limbs, and (ii) eczematous lesions on any other parts of body accompanied by xerosis.

CONCLUSIONS

In China, the prevalence of AD in infancy is 30.48% according to clinical diagnosis of dermatologists. The novel Chinese diagnostic criteria for AD in infants show a higher sensitivity and comparable specificity.

Longitudinal atopic dermatitis control and persistence vary with timing of disease onset in children: A cohort study

BACKGROUND

Wide variation exists in the timing of atopic dermatitis (AD) disease onset among children. Distinct trajectories of early-onset, mid-onset, and late-onset AD have been previously described.

OBJECTIVE

To evaluate longitudinal disease control and persistence with respect to age at onset of AD.

METHODS

A cohort study was performed using the Pediatric Eczema Elective Registry, a prospective observational cohort of subjects with childhood-onset AD. AD control and persistence were assessed biannually for up to 10 years.

RESULTS

A total of 8015 subjects with 41,934 person-years of follow-up were included. In longitudinal analyses using generalized linear latent and mixed modeling, older age at onset of AD was associated with better disease control and less-persistent AD. For each additional year of age at onset of AD, the adjusted odds ratios for poorer AD control and for persistent AD were 0.93 (95% confidence interval, 0.91-0.94) and 0.84 (95% confidence interval, 0.80-0.88), respectively. Differences in AD control and persistence among subjects with early-, mid-, and late-onset AD were most pronounced from early adolescence onward.

LIMITATIONS

Misclassification bias may arise from using self-reported data on age at onset. Attrition and missing data in longitudinal studies may introduce bias.

CONCLUSION

Early-, mid-, and late-onset pediatric AD appear to be clinically distinct subtypes of the disease.

Clinical Characteristics and Genetic Variations in Early-Onset Atopic Dermatitis Patients

Background

Hereditary factors contribute to atopic dermatitis (AD) development. We developed the reverse blot hybridization assay (REBA) kit to simultaneously detect variations in skin barrier- and immune response-related genes prevalent in Korean AD patients.

Objective

To identify genetic variations and clinical characteristics that could predict early AD development.

Methods

We compared AD-related genetic variations between early-onset AD subjects and non-AD controls, and clinical characteristics and genetic variations between early- and late-onset AD subjects. We compared 28 early-onset AD subjects and 57 non-AD controls from a birth cohort and 108 early- (age ≤3 years) and 90 late-onset AD subjects and 189 non-AD controls from a university hospital. Genetic variations were detected via REBA.

Results

There were no differences in AD-related genetic variation between early-onset AD subjects and non-AD controls in the birth cohort. When the birth cohort and hospital populations were combined, early-onset AD subjects and non-AD controls showed different frequencies of genetic variations of KLK7, SPINK5 1156, DEFB1, IL5RA, IL12RB1a, and IL12RB1b. No differences in the frequency of genetic variations were observed between early- and late-onset AD subjects. Immunoglobulin E positivity for house dust mites was prevalent in late-onset AD subjects. A family history of atopic diseases was associated with early-onset AD.

Conclusion

No AD-related genetic variations could predict early AD development in Koreans, even though neonates with a family history of atopic diseases are likely to develop AD at ≤3 years of age. Environmental exposure may be more important than genetic variation in determining the onset age of AD.

Personalized medicine-concepts, technologies, and applications in inflammatory skin diseases

The current state, tools, and applications of personalized medicine with special emphasis on inflammatory skin diseases like psoriasis and atopic dermatitis are discussed. Inflammatory pathways are outlined as well as potential targets for monoclonal antibodies and small-molecule inhibitors.

Phenotypes of allergic diseases in children and their application in clinical situations

Allergic diseases, including allergic rhinitis, asthma, and atopic dermatitis, are common heterogeneous diseases that encompass diverse phenotypes and different pathogeneses. Phenotype studies of allergic diseases can facilitate the identification of risk factors and their underlying pathophysiology, resulting in the application of more effective treatment, selection of better treatment responses, and prediction of prognosis for each phenotype. In the early phase of phenotype studies in allergic diseases, artificial classifications were usually performed based on clinical features, such as triggering factors or the presence of atopy, which can result in the biased classification of phenotypes and limit the characterization of heterogeneous allergic diseases. Subsequent phenotype studies have suggested more diverse phenotypes for each allergic disease using relatively unbiased statistical methods, such as cluster analysis or latent class analysis. The classifications of phenotypes in allergic diseases may overlap or be unstable over time due to their complex interactions with genetic and encountered environmental factors during the illness, which may affect the disease course and pathophysiology. In this review, diverse phenotype classifications of allergic diseases, including atopic dermatitis, asthma, and wheezing in children, allergic rhinitis, and atopy, are described. The review also discusses the applications of the results obtained from phenotype studies performed in other countries to Korean children. Consideration of changes in the characteristics of each phenotype over time in an individual’s lifespan is needed in future studies.

Phenotypes of atopic dermatitis identified by cluster analysis in early childhood

Atopic dermatitis is a chronic, relapsing, inflammatory skin disease that usually appears in early childhood and develops into a heterogeneous disease during childhood. The clinical course and treatment for atopic dermatitis can differ according to its phenotype and/or endotype. This study aimed to identify clinical phenotypes of atopic dermatitis in early childhood. Data were obtained from 572 children under 3 years of age with atopic dermatitis. Cluster analysis applied to 11 variables, and we identified four clusters of atopic dermatitis. Children in cluster A (n = 141) had early-onset atopic dermatitis with high blood eosinophil counts, serum total immunoglobulin E and rates of sensitization to food allergens. Children in cluster B (n = 218) had early-onset atopic dermatitis with low blood eosinophil counts, serum total immunoglobulin E and rates of sensitization to both food and inhalant allergens. Children in cluster C (n = 53) had early-onset atopic dermatitis with high C-reactive protein levels and white blood cell counts. Children in cluster D (n = 160) had middle-onset atopic dermatitis with high serum total immunoglobulin E and rates of sensitization to inhalant allergens. Cluster A had the highest Scoring for Atopic Dermatitis and transepidermal water loss values. Age at onset, age at diagnosis, white blood cell count, eosinophil count, C-reactive protein and serum total immunoglobulin E level were the strongest predictors of cluster assignment. Analysis of these six variables alone resulted in correct classification of 95.5% of the subjects. These results support the heterogeneity of atopic dermatitis, even in early childhood.

The atopic march and atopic multimorbidity: Many trajectories, many pathways

The atopic march recognizes the increased occurrence of asthma, allergic rhinitis, or both after atopic dermatitis (AD) onset. Mechanisms for developing atopic comorbidities after AD onset are poorly understood but can involve the impaired cutaneous barrier, which facilitates cutaneous sensitization. The association can also be driven or amplified in susceptible subjects by a systemic T_H2-dominant immune response to cutaneous inflammation. However, these associations might merely involve shared genetic loci and environmental triggers, including microbiome dysregulation, with the temporal sequence reflecting tissue-specific peak time of occurrence of each disease, suggesting more of a clustering of disorders than a march. Prospective longitudinal cohort studies provide an opportunity to explore the relationships between postdermatitis development of atopic disorders and potential predictive phenotypic, genotypic, and environmental factors. Recent investigations implicate disease severity and persistence, age of onset, parental atopic history, filaggrin (FLG) mutations, polysensitization, and the nonrural environment among risk factors for development of multiple atopic comorbidities in young children with AD. Early intervention studies to repair the epidermal barrier or alter exposure to the microbiome or allergens might elucidate the relative roles of barrier defects, genetic locus alterations, and environmental exposures in the risk and sequence of occurrence of T_H2 activation disorders.

Association Between Maternal Pre-Pregnancy Body Mass Index, Gestational Weight Gain, and Offspring Atopic Dermatitis: A Prospective Cohort Study

BACKGROUND

Maternal weight status may contribute to the development of atopic disorders in children.

OBJECTIVE

The objective of this study was to assess associations of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) with risk of atopic dermatitis (AD) in children.

METHODS

Maternal pre-pregnancy BMI and GWG were assessed by questionnaire through the Growing Up Today Study (GUTS), a prospective cohort study of US children. Mothers reported whether GUTS participants had ever been diagnosed with AD by a clinician in either 1997 or 1999, when GUTS participants were between 10 and 17 years old. We used multivariable logistic regression to estimate the association of BMI and GWG with AD in offspring (expressed as odds ratios [ORs] with 95% CIs).

RESULTS

Among 13,269 GUTS participants, 2,058 (16%) had childhood AD. Higher maternal pre-pregnancy BMI was not associated with AD (P trend = .48). In contrast, GWG was associated with increased AD risk (P trend = .005). Compared with children of mothers who gained 25 to 34 lb, children of mothers who gained 35 to 44 lb (OR, 1.11; 95% CI, 0.98-1.26) and 45 lb or more (OR, 1.23; 95% CI, 1.05-1.43) had an increased risk of AD. These associations appeared stronger with pre-pregnancy BMI greater than 25 (GWG, 35-44 lb: OR, 1.20; 95% CI, 0.84-1.69; GWG, ≥45 lb: OR, 1.57; 95% CI, 1.07-2.31), but the statstical interaction between BMI and GWG was not significant.

CONCLUSIONS

In this study, increased GWG was associated with increased risk of AD in offspring. This supports existing evidence that prenatal exposures contribute to the development of atopic disorders.

Human and computational models of atopic dermatitis: A review and perspectives by an expert panel of the International Eczema Council

Atopic dermatitis (AD) is a prevalent disease worldwide and is associated with systemic comorbidities representing a significant burden on patients, their families, and society. Therapeutic options for AD remain limited, in part because of a lack of well-characterized animal models. There has been increasing interest in developing experimental approaches to study the pathogenesis of human AD in vivo, in vitro, and in silico to better define pathophysiologic mechanisms and identify novel therapeutic targets and biomarkers that predict therapeutic response. This review critically appraises a range of models, including genetic mutations relevant to AD, experimental challenge of human skin in vivo, tissue culture models, integration of “omics” data sets, and development of predictive computational models. Although no one individual model recapitulates the complex AD pathophysiology, our review highlights insights gained into key elements of cutaneous biology, molecular pathways, and therapeutic target identification through each approach. Recent developments in computational analysis, including application of machine learning and a systems approach to data integration and predictive modeling, highlight the applicability of these methods to AD subclassification (endotyping), therapy development, and precision medicine. Such predictive modeling will highlight knowledge gaps, further inform refinement of biological models, and support new experimental and systems approaches to AD. (J Allergy Clin Immunol 2019;143:36–45.)

Diagnosing atopic dermatitis in infancy: Questionnaire reports vs criteria-based assessment

BACKGROUND

Persisting atopic dermatitis (AD) is known to be associated with more serious allergic diseases at later ages; however, making an accurate diagnosis during infancy is challenging. We assessed the diagnostic performance of questionnaire-based AD measures with criteria-based in-person clinical assessments at age 1 year and evaluated the ability of these diagnostic methods to predict asthma, allergic rhinitis and food allergies at age 5 years.

METHODS

Data relate to 3014 children participating in the Canadian Healthy Infant Longitudinal Development (CHILD) Study who were directly observed in a clinical assessment by an experienced healthcare professional using the UK Working Party criteria. The majority (2221; 73.7%) of these children also provided multiple other methods of AD ascertainment: a parent reporting a characteristic rash on a questionnaire, a parent reporting the diagnosis provided by an external physician and a combination of these two reports.

RESULTS

Relative to the direct clinical assessment, the area under the Receiver Operating Characteristic curve for a parental report of a characteristic rash, reported physician diagnosis and a combination of both were, respectively, 0.60, 0.69 and 0.70. The strongest predictor of asthma at 5 years was AD determined by criteria-based in-person clinical assessment followed by the combination of parental and physician report.

CONCLUSIONS

These findings suggest that questionnaire data cannot accurately substitute for assessment by experienced healthcare professionals using validated criteria for diagnosis of atopic dermatitis. Combining the parental report with diagnosis by a family physician might sometimes be appropriate (eg to avoid costs of a clinical assessment).

Classifying atopic dermatitis: protocol for a systematic review of subtypes (phenotypes) and associated characteristics

INTRODUCTION

Atopic dermatitis is a complex disease with differing clinical presentations. Many attempts have been made to identify uniform subtypes, or phenotypes, of atopic dermatitis in order to identify different aetiologies, improve diagnosis, estimate more accurate clinical prognoses, inform treatment andmanagement or predict treatment efficacy andeffectiveness. However, no consensus yet exists on exactly what defines these phenotypes or how many there are and whether they are genuine or statistical artefacts. This review aims to identify previously reported phenotypes of atopic dermatitis, the features used to define them and any characteristics or clinical outcomes significantly associated with them.

METHODS AND ANALYSIS

We will search Ovid Embase, Ovid MEDLINE and Web of Science from inception to the latest available date at the time of the search for studies attempting to classify atopic dermatitis in humans using any cross-sectional or longitudinal epidemiological or interventional design. Primary outcomes are atopic dermatitis phenotypes, features used to define them and characteristics associated with them in subsequent analyses. A secondary outcome is the methodological approach used to derive them. Two reviewers will independently screen titles and abstracts for inclusion, extract data and assess study quality. We will present the results of this review descriptively and with frequencies where possible.

ETHICS AND DISSEMINATION

Ethical approval is not required for this study as it is a systematic review. We will report results from this systematic review in a peer-reviewed journal. The main value of this study will be to inform further research.

PROSPERO REGISTRATION NUMBER

CRD42018087500.

Atopic dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease, with a lifetime prevalence of up to 20% and substantial effects on quality of life. AD is characterized by intense itch, recurrent eczematous lesions and a fluctuating course. AD has a strong heritability component and is closely related to and commonly co-occurs with other atopic diseases (such as asthma and allergic rhinitis). Several pathophysiological mechanisms contribute to AD aetiology and clinical manifestations. Impairment of epidermal barrier function, for example, owing to deficiency in the structural protein filaggrin, can promote inflammation and T cell infiltration. The immune response in AD is skewed towards T helper 2 cell-mediated pathways and can in turn favour epidermal barrier disruption. Other contributing factors to AD onset include dysbiosis of the skin microbiota (in particular overgrowth of Staphylococcus aureus), systemic immune responses (including immunoglobulin E (IgE)-mediated sensitization) and neuroinflammation, which is involved in itch. Current treatments for AD include topical moisturizers and anti-inflammatory agents (such as corticosteroids, calcineurin inhibitors and cAMP-specific 3',5'-cyclic phosphodiesterase 4 (PDE4) inhibitors), phototherapy and systemic immunosuppressants. Translational research has fostered the development of targeted small molecules and biologic therapies, especially for moderate-to-severe disease.