Subtypes of atopic dermatitis: From phenotype to endotype.

Atopic dermatitis (AD) is a heterogenous disorder and can be classified into different types. Stratification of subtypes may enable personalized medicine approaches. AD can be categorized into the IgE-high, extrinsic subtype and the IgE-normal, intrinsic subtype. While extrinsic AD is the major subtype possessing skin barrier impairment (high incidence of filaggrin mutations), intrinsic AD occupies about 20% of AD with female dominance and preserved barrier. Extrinsic AD exhibits protein allergy and food allergy, but intrinsic AD shows metal allergy possibly in association with suprabasin deficiency. In particular, accumulated knowledge of food allergy has more clearly characterized extrinsic AD. European American (EA) and Asian AD subtypes have been also proposed. Asian patients with AD are characterized by a unique blended immune dysregulation and barrier feature phenotype between EA patients with AD and those with psoriasis. In another ethnic study, filaggrin loss-of-function mutations are not prevalent in African American patients with AD, and Th1/Th17 attenuation and Th2/Th22 skewing were seen in these patients. Recent endotype classification provides new insights for AD and other allergic disorders. Endotype is defined as the molecular mechanisms underlying the visible features/phenotype. Endotype repertoire harbors activation of type 2 cytokines, type 1 cytokines, and IL-17/IL-22, impairment of epidermal barrier, and abnormalities of intercellular lipids. Classification of endotype has been attempted with serum markers. These lines of evidence indicate a need for personalized or precision medicine appropriate for each subtype of AD.

Unraveling heterogeneity in pediatric atopic dermatitis: Identification of serum biomarker based patient clusters.

BACKGROUND: Increasing evidence shows that pediatric atopic dermatitis (AD) differs from adult AD on a biologic level. Broad biomarker profiling across a wide range of ages of pediatric patients with AD is lacking. OBJECTIVE: Our aim was to identify serum biomarker profiles in children with AD aged 0 to 17 years and compare these profiles with those previously found in adults with AD. METHODS: Luminex multiplex immunoassays were used to measure 145 biomarkers in serum from 240 children with AD (aged 0-17 years). Principal components analysis followed by unsupervised k-means clustering were performed to identify patient clusters. Patients were stratified into age groups (0-4 years, 5-11 years, and 12-17 years) to assess association between age and cluster membership. RESULTS: Children aged 0 to 4 years had the highest levels of TH1 cell-skewing markers and lowest levels of TH17 cell-related markers. TH2 cell-related markers did not differ significantly between age groups. Similar to the pattern in adults, cluster analysis identified 4 distinct pediatric patient clusters (TH2 cell/retinol-dominant, skin-homing-dominant, TH1 cell/TH2 cell/TH17 cell/IL-1-dominant, and TH1 cell/IL-1/eosinophil-inferior clusters). Only the TH1 cell/TH2 cell/TH17 cell/IL-1-dominant cluster resembled 1 of the previously identified adult clusters. Although no association with age or age of onset seemed to be found, disease severity was significantly associated with the skin-homing-dominant cluster. CONCLUSION: Four distinct patient clusters based on serum biomarker profiles could be identified in a large cohort of pediatric patients with AD, of which 1 was similar to previously identified adult clusters. The identification of endotypes driven by distinct underlying immunopathologic pathways might be useful to define pediatric patients with AD who are at risk of persistent disease and may necessitate different targeted treatment approaches.

From Emollients to Biologicals: Targeting Atopic Dermatitis.

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease and significantly impacts patients' lives, particularly in its severe forms. AD clinical presentation varies over the course of the disease, throughout different age groups, and across ethnicities. AD is characterized by a spectrum of clinical phenotypes as well as endotypes. Starting from the current description of AD pathogenesis, this review explores the rationale of approved AD therapies from emollients to biologicals and introduces novel promising drugs.

Atopic dermatitis or eczema? Consequences of ambiguity in disease name for biomedical literature mining.

BACKGROUND: Biomedical research increasingly relies on computational approaches to extract relevant information from large corpora of publications. OBJECTIVE: To investigate the consequence of the ambiguity between the use of terms "Eczema" and "Atopic Dermatitis" (AD) from the Information Retrieval perspective, and its impact on meta-analyses, systematic reviews and text mining. METHODS: Articles were retrieved by querying the PubMed using terms 'eczema' (D003876) and "dermatitis, atopic" (D004485). We used machine learning to investigate the differences between the contexts in which each term is used. We used a decision tree approach and trained model to predict if an article would be indexed with eczema or AD tags. We used text-mining tools to extract biological entities associated with eczema and AD, and investigated the discrepancy regarding the retrieval of key findings according to the terminology used. RESULTS: Atopic dermatitis query yielded more articles related to veterinary science, biochemistry, cellular and molecular biology; the eczema query linked to public health, infectious disease and respiratory system. Medical Subject Headings terms associated with "AD" or "Eczema" differed, with an agreement between the top 40 lists of 52%. The presence of terms related to cellular mechanisms, especially allergies and inflammation, characterized AD literature. The metabolites mentioned more frequently than expected in articles with AD tag differed from those indexed with eczema. Fewer enriched genes were retrieved when using eczema compared to AD query. CONCLUSIONS AND CLINICAL RELEVANCE: There is a considerable discrepancy when using text mining to extract bio-entities related to eczema or AD. Our results suggest that any systematic approach (particularly when looking for metabolites or genes related to the condition) should be performed using both terms jointly. We propose to use decision tree learning as a tool to spot and characterize ambiguity, and provide the source code for disambiguation at https://github.com/cfrainay/ResearchCodeBase.

Feline allergic diseases: introduction and proposed nomenclature.

BACKGROUND: Feline allergic diseases present as challenging problems for clinicians, not least because of the number of reaction patterns of the feline skin, none of which are specific for allergy. Furthermore, there is some controversy over the nomenclature that should be used in their description. OBJECTIVES: To review the literature, assess the status of knowledge of the topic and the extent to which these diseases could be categorized as atopic in nature, and make recommendations concerning nomenclature. METHODS: Atopic diseases in humans and cats were researched. A comparison then was made of the essential features in the two species. RESULTS: There were sufficient similarities between human atopic diseases and the manifestations of feline diseases of presumed allergic aetiology to justify the use of "atopic" to describe some of the feline conditions affecting the skin, respiratory and gastrointestinal tract. However, none of the allergic skin diseases showed features consistent with atopic dermatitis as described in man and the dog. CONCLUSIONS AND CLINICAL IMPORTANCE: The term "Feline Atopic Syndrome" (FAS) is proposed to encompass allergic diseases of the skin, gastrointestinal tract and respiratory tract, and "Feline atopic skin syndrome" (FASS) proposed to describe allergic skin disease associated with environmental allergies. We are not aware of any adverse food reactions in cats that are attributable to causes other than immunological reactions against the food itself. We therefore propose an aetiological definition of "Food Allergy" (FA) to describe such cases.

Confirmation of multiple endotypes in atopic dermatitis based on serum biomarkers.

BACKGROUND: Atopic dermatitis (AD) is a highly heterogeneous disease, both clinically and biologically, whereas patients are still being treated according to a "one-size-fits-all" approach. Stratification of patients into biomarker-based endotypes is important for future development of personalized therapies. OBJECTIVE: Our aim was to confirm previously defined serum biomarker-based patient clusters in a new cohort of patients with AD. METHODS: A panel of 143 biomarkers was measured by using Luminex technology in serum samples from 146 patients with severe AD (median Eczema Area and Severity Index = 28.3; interquartile range = 25.2-35.3). Principal components analysis followed by unsupervised k-means cluster analysis of the biomarker data was used to identify patient clusters. A prediction model was built on the basis of a previous cohort to predict the 1 of the 4 previously identified clusters to which the patients of our new cohort would belong. RESULTS: Cluster analysis identified 4 serum biomarker-based clusters, 3 of which (clusters B, C, and D) were comparable to the previously identified clusters. Cluster A (33.6%) could be distinguished from the other clusters as being a "skin-homing chemokines/IL-1R1-dominant" cluster, whereas cluster B (18.5%) was a "TH1/TH2/TH17-dominant" cluster, cluster C (18.5%) was a "TH2/TH22/PARC-dominant" cluster, and cluster D (29.5%) was a "TH2/eosinophil-inferior" cluster. Additionally, by using a prediction model based on our previous cohort we accurately assigned the new cohort to the 4 previously identified clusters by including only 10 selected serum biomarkers. CONCLUSION: We confirmed that AD is heterogeneous at the immunopathologic level and identified 4 distinct biomarker-based clusters, 3 of which were comparable with previously identified clusters. Cluster membership could be predicted with a model including 10 serum biomarkers.

A caregiver-reported global severity assessment in pediatric atopic eczema: the Comano score.

Atopic eczema (AE) is the most common inflammatory skin disease in infancy and its prevalence is rising worldwide. It has a wide social impact on the affected children and their families' lives. AE can have a chronic and heterogeneous course, with periods of remission and relapse of the clinical manifestations. For this reason, its severity assessment through standardized outcome measures becomes a fundamental guide for health professionals, who can manage AE following evidence-based medicine principles in their everyday clinical practice or in clinical trials.Several scoring systems have been recognized to assess the clinical manifestations of AE, both from the physician's and the patient's point of view. Despite the scoring systems standardized for adults, there are very few published options about the expression of a patient/caregiver-centered global severity assessment specifically for pediatric AE. For this reason, the aim of our study was to evaluate a new, quick, user-friendly and feasible caregiver-reported global severity assessment for pediatric AE. Based on a 0-10 numerical rating scale in pediatric AE, we named this scoring system the Comano score.We carried out a cross-sectional observational study enrolling a total of 867 patients aged from 1 to 16 years (males 49.5%, mean patient's age 5.9 years, standard deviation ±3.6 years) with a previous doctor-confirmed diagnosis of AE, who underwent balneotherapy at Comano Thermal Center (Comano, Trentino, Italy). A strong correlation between Comano score and SCORing Atopic Dermatitis (SCORAD) was observed (r = 0.74, p < 0.0001).According to our results, the Comano score may be a promising new tool for the expression of a caregiver-reported global severity assessment in pediatric AE. However, further data are needed to confirm our preliminary findings before health professionals can use this scoring system in their everyday clinical practice to manage pediatric AE. Still, as a patient-focused measure, the Comano score may facilitate delivering person-centered care so as to define a measure for a clinical impact that can be meaningful to the subject, which is gaining importance in modern medicine.

Atopic dermatitis in young adult Italian males: persistent and adult-onset varieties did not clinically differ, as for allergological variables.

BACKGROUND: The prevalence of adult atopic dermatitis (AD) in general population range from 2.6% to 8% according to objective diagnosis in selected groups of people. The adult-onset AD is the clinical form arising de novo in adulthood. The aim of this study was to detect retrospectively the prevalence of AD in Italian general population, examining a sample of young Italian males affected by AD, which was representative of people of same sex and age, and to point out the clinical and allergological differences between the persistent and adult-onset form. METHODS: 198,730 potential male conscripts were visited in Italian Navy and Air Force Recruitment's Centers in Taranto to evaluate their fitness to recruitment. All the young men who showed eczema were referred to Italian Navy Hospital. The diagnosis of AD was stated according to Hanifin and Rajka's criteria. All the patients were patch and prick tested. RESULTS: One hundred twenty-four cases of AD were diagnosed, with a prevalence of 6.2 cases for 10,000 subjects (95% CI: 5.2-7.4). The subjects with the persistent form were 68 (75.6%; 95% CI: 66.7-84.4) vs. 26 patients with the adult-onset form (21.0%; 95% CI: 13.8-28.1). No statistical difference in clinical and allergological variables was showed between the persistent and adult-onset AD. CONCLUSIONS: The prevalence of adult AD in a large sample of young males - representative of the general population of same age and sex - is appreciably lower than the rates previously reported. No clinical feature or allergological variable discriminate between persistent vs. adult-onset varieties.

Development and validation of a graphic 2D investigator's global assessment instrument for grading the overall severity of atopic dermatitis in dogs.

BACKGROUND: Clinical trials enrolling dogs with atopic dermatitis (AD) use validated instruments that aggregate the extent and severity of selected skin lesions; none of these provides a global assessment of the severity of all lesions. OBJECTIVES: To validate an Investigator Global Assessment (IGA) instrument to globally evaluate the severity of skin lesions in dogs with AD. ANIMALS: Forty dogs with AD. METHODS AND MATERIALS: A 2D graphic IGA (2D-IGA) instrument was created to subjectively score, with a single dot, the overall extent and severity of all canine AD lesions. This tool was tested for its validity (content, construct and criterion), reliability (inter- and intraobserver) and sensitivity to change. RESULTS: The content of the 2D-IGA was first validated by a supportive vote by the International Committee of Allergic Diseases of Animals (ICADA) membership. Its construct was verified by positive correlations between the 2D-IGA scores and those of the Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) and the Canine Atopic Dermatitis Lesion Index (CADLI) (Spearman's rank-order correlation, P < 0.0001). The positive correlation (P < 0.0001) between an Owner Global Assessment of Disease Severity (OGADS) and the 2D-IGA indirectly satisfied its criterion. Scores graded by the same investigator hours apart and those between investigators were positively correlated (P < 0.0001), thereby validating this scale's intra- and interobserver reliabilities. Finally, the changes in 2D-IGA values during treatment were correlated positively with scores of an Owner Global Assessment of Treatment Efficacy (OGATE; P < 0.0001), thus showing its sensitivity to change. CONCLUSIONS AND CLINICAL IMPORTANCE: This novel 2D-IGA is a simple static graphic instrument that could be useful for clinical trials testing the efficacy of interventions for canine AD.

Clinical Phenotypes of Severe Cutaneous Drug Hypersensitivity Reactions.

Drug hypersensitivity reactions are clinically heterogenous ranging from mild to severe. Most drug hypersensitivity reactions are accompanied by cutaneous manifestations. Fever, mucous membrane involvement, large blisters, facial oedema, pustulosis and visceral involvement are clinical features that lead to suspicion of severe adverse drug reactions. Severe cutaneous adverse drug reactions (SCARs) include Stevens-Johnson syndrome, toxic epidermal necrolysis, drug rash eosinophilia and systemic symptoms, acute generalized exanthematous pustulosis. Serum sickness like reactions, drug induced vasculitis and generalized bullous fixed drug eruptions are less severe clinical entities. SCARs are uncommon but associated with significant morbidity and mortality. Physician should be aware of specific red flags and danger signs to immediately identify these reactions. Immediate drug withdrawal is mandatory. Early diagnosis and appropriate treatment significantly affect the prognosis of the disease. The purpose of our review is to discuss clinical phenotypes of severe cutaneous drug hypersensitivity reactions.

Atopic dermatitis endotypes and implications for targeted therapeutics.

Recent research advancements indicate that atopic dermatitis (AD) is a complex disease characterized by different subtypes/phenotypes based on age, disease chronicity, ethnicity, filaggrin and IgE status, and underlying molecular mechanisms/endotypes. This heterogeneity advocates against the traditional "one-size-fits-all" therapeutic approaches still used to manage AD. Precision medicine approaches, striving for targeted, tailored, endotype-driven disease prevention and treatment, rely on detailed definitions of the disease's variability across different phenotypes. Studies have shown that AD harbors different endotypes across different age groups and ethnicities and according to IgE levels and filaggrin mutation status. These include European American versus Asian patients, children versus adults, intrinsic versus extrinsic (IgE status) disease, and patients with and without filaggrin mutations. Therapies targeting different cytokine axes and other mechanisms involved in disease pathogenesis, which are currently being tested for patients with AD across the disease spectrum, will expand our ability to dissect the relative contribution of each of these pathways to disease perpetuation.

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.

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.

Association of oxidative stress and dynamic thiol-disulphide homeostasis with atopic dermatitis severity and chronicity in children: a prospective study.

BACKGROUND: Oxidative stress (OS) has an important effect on the pathogenesis of atopic dermatitis (AD). Thiols are antioxidants that regulate intracellular redox metabolism and protect keratinocytes against OS damage in the stratum corneum. AIM: To investigate dynamic thiol-disulphide homeostasis (dTDH) as a novel OS parameter in children with AD, and its relationship with disease severity and chronicity. METHODS: Severity of AD was determined by using the instruments SCORing Atopic Dermatitis (SCORAD) and Eczema Area And Severity Index (EASI) upon enrolment in the study (SCORAD1 and EASI1 ) and after 1 year (SCORAD2 and EASI2 ). Native thiol, total thiol and disulphide levels were measured as novel OS parameters, and the ratios of disulphide/native thiol, disulphide/total thiol and native/total thiol were calculated as dTDH. RESULTS: In the AD group, the serum disulphide level and the ratios of disulphide/native thiol and disulphide/total thiol were significantly lower than in healthy controls (P = 0.01, P < 0.01 and P < 0.01, respectively). There was no significant association between OS parameters and disease severity (P > 0.05). SCORAD2 and EASI2 were positively correlated with disulphide/native thiol ratio (r = 0.29, P < 0.03 and r = 0.35, P < 0.01, respectively), whereas they were negatively correlated with the native/total thiol ratio (r = -0.30, P = 0.02 for both). CONCLUSIONS: Both OS and impaired dTDH were found to be related to childhood AD. None of the OS parameters was associated with AD severity. dTDH is a possible diagnostic tool to predict AD chronicity.

Classification and possible bacterial infection in outpatients with eczema and dermatitis in China: A cross-sectional and multicenter study.

Little is known about the classification and bacterial infection in outpatients with eczema and dermatitis in China.To investigate the prevalence of eczema and dermatitis in outpatients of dermatology clinics in China, examine classification and proportion of common types of dermatitis and the possible bacterial infection, and analyze the possible related factors.Outpatients with eczema or dermatitis from 39 tertiary hospitals of 15 provinces in mainland China from July 1 to September 30, 2014, were enrolled in this cross-sectional and multicenter study. Among 9393 enrolled outpatients, 636 patients (6.7%) were excluded because of incomplete information.The leading subtypes of dermatitis were unclassified eczema (35.5%), atopic dermatitis (13.4%), irritant dermatitis (9.2%), and widespread eczema (8.7%). Total bacterial infection rate was 52.3%, with widespread eczema, stasis dermatitis, and atopic dermatitis being the leading three (65.7%, 61.8%, and 61.4%, respectively). Clinically very likely bacterial infection has a significant positive correlation with disease duration, history of allergic disease, history of flexion dermatitis, and severe itching.Atopic dermatitis has become a common subtype of dermatitis in China. Secondary bacterial infection is common in all patients with dermatitis, and more attentions should be paid on this issue in other type of dermatitis apart from atopic dermatitis.

Typical and atypical clinical appearance of atopic dermatitis.

Atopic dermatitis is a complex, systemic inflammatory disorder associated with a variety of clinical features. The original criteria of Hanifin and Rajka include major criteria and a list of about two dozen minor criteria however, even the minor criteria do not include some features of atopic dermatitis noted less commonly but still seen with some frequency. This contribution first reviews the common clinical appearance of atopic dermatitis in infancy, childhood, and adulthood, as well as the less typical appearances, including lichenoid atopic dermatitis; juvenile plantar dermatosis; nummular-type atopic dermatitis; follicular atopic dermatitis; alopecia of atopic dermatitis; eczema coxsackium; and psoriasiform, perineal, and lip licker's dermatitis. The clinician will be able to recognize and treat rarer forms of atopic dermatitis and incorporate this into their daily practice.

Atopic dermatitis characteristics and medication-use patterns in school-age children with AD and asthma symptoms.

BACKGROUND: Atopic dermatitis (AD) and asthma often coexist. Both diseases can have a major impact on the lives of children with AD and their caregivers. AIM: To investigate the association of patient characteristics, comorbidities and impact of AD on children who have both asthma and AD. METHODS: Children with AD (n = 140) were selected from a larger cohort of children with a reported use of asthma medication. The Children's Dermatology Life Quality Index (CDLQI) was used to assess Quality of Life (QoL), and the Self-Assessed Eczema Area and Severity Index (SA-EASI) was used to measure AD severity. Characteristics assessed included: age, sex, and the number and type of atopic comorbidities. Medication use for AD was defined using the total number of AD prescriptions, the number of different topical AD prescriptions and the highest potency topical corticosteroid (TCS) used. Determinants of AD severity and QoL were evaluated using Spearman rank tests. RESULTS: The following factors were most strongly associated with a lower QoL: characteristics of AD lesions (Spearman Rs = 0.61-0.69, P < 0.01), a higher SA-EASI score (Rs = 0.54, P < 0.01) and a larger number of different topical AD prescriptions (Rs = 0.38, P < 0.01). The following factors were correlated with more severe AD: age (Rs = -0.36, P < 0.01), larger number of different TCS preparations used (Rs = 0.27, P < 0.05) and larger number of TCS prescriptions (Rs = 0.25, P < 0.05). CONCLUSION: In children with asthma and AD, the number of TCS preparations used is associated with lower QoL and increased AD severity.