Atopic dermatitis phenotype with early onset and high serum IL-13 is linked to the new development of bronchial hyperresponsiveness in school children

Developmental trajectories of atopic dermatitis with multiomics approaches in the infant gut: COCOA birth cohort

BACKGROUND

An understanding of the phenotypes and endotypes of atopic dermatitis (AD) is essential for developing precision therapies. Recent studies have demonstrated evidence for the gut-skin axis in AD.

OBJECTIVE

We sought to determine the natural course and clinical characteristics of AD phenotypes and investigate their mechanisms on the basis of multiomics analyses.

METHODS

Latent class trajectory analysis was used to classify AD phenotypes in 2247 children who were followed until age 9 years from the COhort for Childhood Origin of Asthma and allergic diseases birth cohort study. Multiomics analyses (microbiome, metabolites, and gut epithelial cell transcriptome) using stool samples collected at age 6 months were performed to elucidate the underlying mechanisms of AD phenotypes.

RESULTS

Five AD phenotypes were classified as follows: never/infrequent, early-onset transient, intermediate transient, late-onset, and early-onset persistent. Early-onset persistent and late-onset phenotypes showed increased risks of food allergy and wheezing treatment ever, with bronchial hyperresponsiveness evident only in the early-onset persistent phenotype. Multiomics analyses revealed a significantly lower relative abundance of Ruminococcus gnavus and a decreased gut acetate level in the early-onset persistent phenotype, with potential associations to ACSS2, Janus kinase-signal transducer and activator of transcription signaling, and systemic TH2 inflammation. The early-onset transient phenotype was associated with adenosine monophosphate-activated protein kinase (AMPK) and/or chemokine signaling regulation, whereas the late-onset phenotype was linked with IL-17 and barrier dysfunction.

CONCLUSIONS

Multiomics profiling in early life may offer insights into different mechanisms underlying AD phenotypes in children.

Predictive Factors for Long-Term High Responders to Upadacitinib Treatment in Patients with Atopic Dermatitis

Background: Upadacitinib, a Janus kinase 1 inhibitor, is an effective medicine for moderate-to-severe atopic dermatitis (AD). Identifying long-term responders to upadacitinib is crucial for optimal treatment strategies in real-world clinical practice. To identify predictive factors for long-term high responders to upadacitinib 15 mg or 30 mg, defined as achievers of investigator's global assessment (IGA) 0/1 with ≥2-point improvement from baseline IGA at week 48. Methods: A retrospective study was conducted from August 2021 to September 2023 on 63 AD patients treated with upadacitinib 15 mg and 31 patients with 30 mg. Patients of each group were categorized into long-term high responders (achievers of IGA 0/1 at week 48) and low responders (non-achievers). We compared baseline values of clinical indexes and laboratory parameters between long-term responders and nonresponders. Results: In 15 mg group, long-term high responders showed lower rate of bronchial asthma (BA), lower values of baseline eczema area and severity index (EASI) of head and neck, IgE, and systemic inflammatory response index (SIRI) compared with low responders. In 30 mg group, long-term high responders showed lower baseline levels of IgE compared with low responders. Conclusion: Patients with lower baseline EASI of head and neck, IgE, or SIRI or without BA and those with lower baseline IgE may have a higher potential to become long-term high responders to upadacitinib 15 mg and 30 mg treatment, respectively.

The role of the skin in the atopic march

Atopic diseases, including atopic dermatitis (AD), food allergy (FA), asthma, and allergic rhinitis (AR) are closely related to inflammatory diseases involving different body sites (i.e. the skin, airway, and digestive tract) with characteristic features including specific IgE to allergens (so-called "atopy") and Th2 cell-mediated inflammation. It has been recognized that AD often precedes the development of other atopic diseases. The progression from AD during infancy to FA or asthma/AR in later childhood is referred to as the "atopic march" (AM). Clinical, genetic, and experimental studies have provided evidence that allergen sensitization occurring through AD skin could be the origin of the AM. Here, we provide an updated review focusing on the role of the skin in the AM, from genetic mutations and environmental factors associated with epidermal barrier dysfunction in AD and the AM to immunological mechanisms for skin sensitization, particularly recent progress on the function of key cytokines produced by epidermal keratinocytes or by immune cells infiltrating the skin during AD. We also highlight the importance of developing strategies that target AD skin to prevent and attenuate the AM.

Biomarkers for phenotype-endotype relationship in atopic dermatitis: a critical review

Atopic dermatitis (AD) is the most common form of chronic skin inflammation with diverse clinical variants. Historically, various AD phenotypes have been grouped together without considering their heterogeneity. This approach has resulted in a lack of phenotype- and endotype-adapted therapeutic strategies. Comprehensive insights into AD pathogenesis have enabled precise medicinal approach for AD. These efforts aimed to redefine the endophenotype of AD and develop various biomarkers for diverse purposes. Among these endeavours, efforts are underway to elucidate the mechanisms (and related biomarkers) that lead to the emergence and progression of atopic diseases originating from AD (e.g., atopic march). This review focuses on diverse AD phenotypes and calls for a definition of endophenotypes. While awaiting scientific validation, these biomarkers ensure predicting disease onset and trajectory and tailoring therapeutic strategies for the future.

Unraveling the gut-skin axis in atopic dermatitis: exploiting insights for therapeutic strategies

Gut microbiota exert functions of high importance in the intestine. Furthermore, there is increasing evidence for its role in immune regulation and maintenance of homeostasis in many physiological processes taking place in distant tissues. In particular, in this review, we explore the impact of metabolites produced by the gut microbiota on the development of atopic dermatitis (AD). Probiotics and prebiotics balance the microbiota and promote the generation of bacterial metabolites, such as short-chain fatty acids and tryptophan derivates, which promote the regulation of the exacerbated AD immune response through regulatory T cells and IL-10 and TGF-β cytokines. Metabolites also have a direct action on keratinocytes once they reach the bloodstream. Besides, probiotics decrease the levels of metabolites associated with AD onset, such as phenols. Understanding all these crosstalk processes between the gut and the skin reveals a number of possibilities, mainly through the manipulation of the gut microbiome, which may represent therapeutic strategies that can contribute to the standard treatments of AD patients to improve their quality of life.

Serum thymic stromal lymphopoietin (TSLP) levels in atopic dermatitis patients: a systematic review and meta-analysis

Thymic stromal lymphopoietin (TSLP) is critical in developing allergic responses, including atopic dermatitis (AD). We systematically reviewed the literature to complete a meta-analysis to quantitatively summarize the levels of serum TSLP in AD. The study was prospectively registered in the PROSPERO database (ID = CRD42021242628). The PUBMED, SCOPUS, and Cochrane Library databases were reviewed, and original articles investigating serum TSLP in AD patients were included. Differences in TSLP levels of AD patients and controls were summarized by standardized mean differences (SMD) using a random effects model. Study quality was assessed by applying the Newcastle‒Ottawa Scale. Fourteen studies, which included 1,032 AD patients and 416 controls, were included. Meta-analysis showed that TSLP levels were significantly higher in the AD group than in the control group (SMD = 2.21, 95% CI 1.37-3.06, p < 0.001). Stratification by geographical region, age, disease severity, TSLP determination method, sample size, and study quality revealed significantly elevated TSLP levels in European AD patients (SMD = 3.48, 95% CI 1.75-5.21, p < 0.0001), adult AD patients (SMD = 4.10, 95% CI 2.00-6.21, p < 0.0001), child AD patients (SMD = 0.83, 95% CI 0.08-1.59, p = 0.031), and all severity groups with AD compared with the control group (mild: SMD = 1.15, 95% CI 0.14-2.16, p = 0.025; moderate: SMD = 2.48, 95% CI 0.33-4.62, p = 0.024; and severe: SMD = 8.28, 95% CI 4.82-11.74, p = 2.72e-6). Noticeably, adults showed higher serum TSLP levels than children with AD, and serum TSL levels increased according to AD severity. In conclusion, our meta-analysis demonstrates that circulating TSLP levels are elevated in patients with AD. Future studies are warranted to further elucidate the sources of heterogeneity.

Disease modification in inflammatory skin disorders: opportunities and challenges

Progress in understanding of the mechanisms underlying chronic inflammatory skin disorders, such as atopic dermatitis and psoriasis vulgaris, has led to new treatment options with the primary goal of alleviating symptoms. In addition, this knowledge has the potential to inform on new strategies aimed at inducing deep and therapy-free remission, that is, disease modification, potentially impacting on associated comorbidities. However, to reach this goal, key areas require further exploration, including the definitions of disease modification and disease activity index, further understanding of disease mechanisms and systemic spillover effects, potential windows of opportunity, biomarkers for patient stratification and successful intervention, as well as appropriate study design. This Perspective article assesses the opportunities and challenges in the discovery and development of disease-modifying therapies for chronic inflammatory skin disorders.

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.

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.

Classification of atopic dermatitis phenotypes according to allergic sensitization by cluster analysis

A cluster study to classify atopic dermatitis (AD) phenotypes into subgroups is required to better understand and manage the disease owing to the heterogeneity of its clinical features. This study aimed to identify the phenotypic subgroups of childhood AD according to allergic sensitization. In 258 children with AD, hierarchical cluster analysis based on specific immunoglobulin (Ig) E sensitization revealed four distinct clusters. Cluster A (n = 71) revealed no IgE sensitization, whereas cluster B (n = 28) showed sensitization to egg white only. Cluster B was highly associated with early-onset AD (<3 months) and a family history of atopic diseases. Cluster C (n = 68) and D (n = 91), sensitized to multiple foods and inhalants, respectively, showed a higher prevalence of skin infection within the last 1 year than others. Cluster D was related to late-onset AD (>12 months) and had more atopic comorbidities. In addition, cluster D showed the most severely impaired health-related quality of life and more frequent use of immunosuppressants. Therefore, childhood AD can be classified into 4 clusters based on the allergic sensitization status, and clinical phenotypes and treatment strategy may be different according to clusters.

Atopic dermatitis endotypes: knowledge for personalized medicine

PURPOSE OF REVIEW

Endotypes are clinically relevant phenotypes that can be explained by molecular mechanisms, and are defined to predict the development, progression, prognosis and responses to treatment on the individual level. This review summarizes atopic dermatitis phenotypes, endotypes and their potential application for personalized medicine.

RECENT FINDINGS

Atopic dermatitis can be classified into several phenotypes according to disease courses that likely have common pathophysiology. The genotype is important to define endotypes, but the value of genotype alone remains somewhat limited in most atopic dermatitis patients. Recent studies have demonstrated that atopic dermatitis phenotypes according to ethnicity or age can be classified into endotypes based on the dominant immunologic markers, that is TH1/TH2/TH17/TH22 cells. Newly developed biologic agents targeting specific cytokines show therapeutic potential in a personalized medicine approach.

SUMMARY

Cytokine-based endotypes in different age groups or ethnic groups have contributed to expanding our understanding of atopic dermatitis. Recent biologics or small molecules can be used for more personalized treatment of atopic dermatitis. Further research using integrated multiomic analysis is needed to define a more detailed classification of endotypes and provide endotype-driven targeted therapies for personalized medicine.

Classifying atopic dermatitis: a systematic review of phenotypes and associated characteristics

Atopic dermatitis is a heterogeneous disease, accompanied by a wide variation in disease presentation and the potential to identify many phenotypes that may be relevant for prognosis and treatment. We aimed to systematically review previously reported phenotypes of atopic dermatitis and any characteristics associated with them. Ovid EMBASE, Ovid MEDLINE and Web of Science were searched from inception till the 12th of February 2021 for studies attempting to classify atopic dermatitis. Primary outcomes are atopic dermatitis phenotypes and characteristics associated with them in subsequent analyses. A secondary outcome is the methodological approach used to derive them. In total, 8,511 records were found. By focusing only on certain clinical phenotypes, 186 studies were eligible for inclusion. The majority of studies were hospital-based (59%, 109/186) and cross-sectional (76%, 141/186). The number of included patients ranged from seven to 526,808. Data-driven approaches to identify phenotypes were only used in a minority of studies (7%, 13/186). Ninety-one studies (49%) investigated a phenotype based on disease severity. A phenotype based on disease trajectory, morphology and eczema herpeticum was investigated in 56 (30%), 22 (12%) and 11 (6%) studies, respectively. Thirty-six studies (19%) investigated morphological characteristics in other phenotypes. Investigated associated characteristics differed between studies. In conclusion, we present an overview of phenotype definitions used in literature for severity, trajectory, morphology and eczema herpeticum, including associated characteristics. There is a lack of uniform and consistent use of atopic dermatitis phenotypes across studies.

A new era of atopic eczema research: Advances and highlights

Atopic eczema (AE) is an inflammatory skin disease with involvement of genetic, immunological and environmental factors. One hallmark of AE is a skin barrier disruption on multiple, highly interconnected levels: filaggrin mutations, increased skin pH and a microbiome dysbiosis towards Staphylococcus aureus overgrowth are observed in addition to an abnormal type 2 immune response. Extrinsic factors seem to play a major role in the development of AE. As AE is a first step in the atopic march, its prevention and appropriate treatment are essential. Although standard therapy remains topical treatment, powerful systemic treatment options emerged in the last years. However, thorough endotyping of the individual patients is still required for ideal precision medicine approaches in future. Therefore, novel microbial and immunological biomarkers were described recently for the prediction of disease development and treatment response. This review summarizes the current state of the art in AE research.

CYT387, a Novel JAK2 Inhibitor, Suppresses IL-13-Induced Epidermal Barrier Dysfunction Via miR-143 Targeting IL-13Rα1 and STAT3

Atopic dermatitis (AD) is a chronic inflammatory skin disease influencing not only children but also adults. It is well-known that AD has a complex pathogenesis without effective therapy. Herein, we explored the function and mechanism of CYT387, a novel JAK2 inhibitor, on epidermal barrier damage. HaCaT cells exposed with high-concentration Ca²⁺ (1.8 mM) for 14 days were recruited for the model of keratinocytes (KC). The cell model of skin barrier damage was induced by IL-13, and KC markers such as filaggrin (FLG), loricrin (LOR), and involucrin (IVL) were detected to judge the success of the model. In this study, we found that miR-143 was lowly expressed whereas IL-13Rα1 was highly expressed in blood cells of patients with AD, indicating their negative correlation. Moreover, IL-13 treatment down-regulated miR-143 and up-regulated activated JAK2 and STAT3 phosphorylation, which was reversed by CYT387 administration. The dual-luciferase reporter assay verified that miR-143 could directly bind to 3'-UTR of IL-13Rα1, as well as STAT3. Furthermore, the function of CYT387 in the skin barrier damage induced by IL-13 was abolished by miR-143 inhibitor. Thus, CYT387 might alleviate IL-13-induced epidermal barrier damage via targeting IL-13Rα1 and STAT3 by miR-143 to repress inflammation. These findings revealed that the protective effects and the underlying mechanisms of CYT387 in AD, which provided evidence that miR-143 may be a novel therapeutic target for AD.

TNF-α (rs1800629) polymorphism modifies the effect of sensitization to house dust mite on asthma and bronchial hyperresponsiveness in children

Asthma is a complex disease, with various genetic and environmental factors implicated in its development. Sensitization to the house dust mite (HDM) is closely linked with the development of respiratory allergies, including asthma. However, some children sensitized to HDM do not complain of any symptoms of respiratory allergies, even though HDM is correlated with an increased risk for developing asthma, suggesting the involvement of other factors. Tumor necrosis factor (TNF)-α is associated with the pathophysiologies of asthma in combination with its genetic polymorphism. The aim of the present study was to elucidate the associations between sensitization to HDM, polymorphism of TNF-α rs1800629, and asthma/bronchial hyperresponsiveness (BHR). Our results revealed that sensitization to HDM is associated with asthma diagnosis in lifetime, current asthma, and BHR in Korean children. Furthermore, the genetic polymorphism of TNF-a rs1800629 was found to modify and interact with these associations. This study suggests that prevention strategies for childhood asthma need to be targeted according to genetic susceptibility.

Association of IL13 genetic polymorphisms with atopic dermatitis: Fine mapping and haplotype analysis

BACKGROUND

Although previous studies had reported an important role of interleukin 13 (IL13) and its genetic polymorphisms in atopic dermatitis (AD), many of these previous reports focused on the missense variant rs20541 (Gln144Arg) without fine mapping of the gene region.

OBJECTIVE

To analyze the potential associations of other IL13 variants and their haplotypes with AD and assess total serum immunoglobulin E (IgE) levels.

METHODS

We performed fine mapping of single-nucleotide polymorphisms (SNPs) within the IL13 gene in a pilot study of 495 children with AD and 444 healthy controls. Then, we conducted a replication study of 757 children with AD and 1620 healthy controls to evaluate the association between the rs20541 variant of IL13 and AD.

RESULTS

In the pilot study, the rs20541 and rs1295685 SNPs in the 3'-untranslated region of IL13 had significant associations with AD (P < .001 and .01, respectively). In addition, 2 haplotypes (BL2_ht1 and BL2_ht2), which harbored the significant rs20541 and rs1295685 SNPs, had an association with AD (minimum P = .006). BL2_ht1 and BL2_ht2 had nominal signals associated with the total serum IgE levels (P < .05) but not with the severity of AD (P > .05). In the replication study, rs20541 was associated with the total serum IgE levels but not with the severity of AD.

CONCLUSION

An additional IL13 gene SNP, rs1295685, has a strong linkage disequilibrium with rs20541, and its haplotypes are associated with AD and the total serum IgE levels.

Interleukin-13: Targeting an underestimated cytokine in atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin condition that has traditionally been considered a paradigmatic type 2 immunity (T2)-driven disease. Interleukin (IL)-4 and IL-13 are both pivotal cytokines involved in the generation of allergic diseases. Currently, besides dupilumab, which blocks the binding of both cytokines to their receptors, a number of new pharmacologic entities have been designed to target both T2 cytokines and/or their receptors and/or receptor-associated signal transduction machinery such as Janus kinases. Recently, IL-13 has been suggested to be the key T2 cytokine driving inflammation in the periphery, while IL-4 may merely have a central effect. There is increasing evidence that this concept holds true for the inflammatory reaction underlying AD, where IL-13 is overexpressed locally and has a significant impact on skin biology, including the recruitment of inflammatory cells, the alteration of the skin microbiome, and the decrease in the epidermal barrier function. This review provides an update on the role of IL-13 in AD and discusses the different strategies aimed at interfering with its biologic activity as well as their potential in a precision medicine approach in the management of AD.

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.

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.

Disentangling the heterogeneity of allergic respiratory diseases by latent class analysis reveals novel phenotypes

BACKGROUND

Refined phenotyping of allergic diseases may unravel novel phenotypes. Conjunctivitis as an independent disorder has never been approached.

AIM

To identify distinct classes of allergic respiratory diseases using latent class analysis (LCA) and distinguish each class using classification and regression tree (CART) analysis.

METHODS

Seven hundred and twenty-eight adults from the Portuguese general population study ICAR had a structured medical interview combined with blood collection, skin prick tests, spirometry with bronchodilation, and exhaled nitric oxide. LCA was applied to 19 variables. The CART algorithm selected the most likely variables distinguishing LCA-classes.

RESULTS

A six-class model was obtained. Class 1 (25%): nonallergic participants without bronchial or ocular symptoms. Classes 2 (22%) and 3 (11%): nasal and ocular (low levels) symptoms without nasal impairment, monosensitized (Class 2) or polysensitized (Class 3). Class 4 (13%): polysensitized participants with high levels of nasal and ocular symptoms, and nasal impairment. Classes 5 (16%) and 6 (14%): high level of nasal, bronchial and ocular symptoms with nasal impairment (non-allergic or polysensitized, respectively). Participants in classes 5 and 6 had more bronchial exacerbations and unscheduled medical visits (P < 0.001). Ocular symptoms were significantly higher in classes with nasal impairment, compared to those without impairment (P < 0.001) or no nasal symptom (P < 0.001). CART highlighted ocular symptoms as the most relevant variable in distinguishing LCA-classes.

CONCLUSION

Novel severe phenotypes of participants with co-occurrence of ocular, nasal and bronchial symptoms, and exacerbation-prone were identified. The tree algorithm showed the importance of the ocular symptoms in the expression of allergic diseases phenotypes.

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).

Clinical phenotypes of bronchial hyperresponsiveness in school-aged children

BACKGROUND

Bronchial hyperresponsiveness (BHR), one of the key features of asthma, has a diverse natural course in school-aged children, but studies on BHR phenotypes are lacking.

OBJECTIVE

To classify BHR phenotypes according to onset age and persistence in children and investigate the characteristics and factors associated with each phenotype in a longitudinal study.

METHODS

This study analyzed 1,305 elementary school children from the Children's Health and Environmental Research (CHEER) study, a 4-year, prospective, follow-up study with 2-year intervals starting at a mean age of 7years. Total serum IgE levels and blood eosinophil counts were measured, and allergy workup, including methacholine challenge tests with the International Study of Asthma and Allergies in Childhood questionnaire, was performed at each survey.

RESULTS

The 4 BHR phenotypes were classified as non-BHR (n = 942 [72.2%]), early-onset transient BHR (n = 201 [15.4%]), late-onset BHR (n = 87 [6.7%]), and early-onset persistent BHR (n = 75 [5.7%]). Early-onset persistent BHR is characterized by an increased eosinophil count, total serum IgE level, sensitization rate, decreased lung function, and increased risk of newly diagnosed asthma during follow-up (adjusted odds ratio, 3.89; 95% confidence interval, 1.70-8.88). The 2 early-onset phenotypes were associated with peripheral airway dysfunction. The late-onset BHR phenotype was related to increased risks of allergic rhinitis symptoms at baseline and later sensitization against inhalant allergens.

CONCLUSION

The early-onset persistent BHR phenotype in school-aged children is associated with high atopic burden and increased risk of newly diagnosed asthma, whereas the late-onset BHR phenotype related with later sensitization and allergic rhinitis symptoms. Diverse BHR phenotypes in children have specific characteristics that require targeted follow-ups.

New insights into the phenotypes of atopic dermatitis linked with allergies and asthma in children: An overview

Atopic dermatitis (AD) is a complex disease with multiple causes and complex mechanistic pathways according to age of onset, severity of the illness, ethnic modifiers, response to therapy and triggers. A group of difficult-to-manage patients characterized by early-onset AD and severe lifelong disease associated with allergic asthma and/or food allergy (FA) has been identified. In this study, we focus on these severe phenotypes, analysing their links with other atopic comorbidities, and taking into account the results from recent cohort studies and meta-analyses. The main hypothesis that is currently proposed to explain the onset of allergic diseases is an epithelial barrier defect. Thus, the atopic march could correspond to an epithelial dysfunction, self-sustained by a secondary allergenic sensitization, explaining the transition from AD to allergic asthma. Furthermore, AD severity seems to be a risk factor for associated FA. Results from population-based, birth and patient cohorts show that early-onset and severe AD, male gender, parental history of asthma, and early and multiple sensitizations are risk factors leading to the atopic march and the development of asthma. The importance of environmental factors should be recognized in these high-risk children and prevention programs adapted accordingly. Effective targeted therapies to restore both barrier function and to control inflammation are necessary; early emollient therapy is an important approach to prevent AD in high-risk children. Clinicians should also keep in mind the specific risk of atopic comorbidities in case of filaggrin loss-of-function mutations and the rare phenotypes of orphan syndromes due to heritable mutations in skin barrier components.

Allergy march of Chinese children with infantile allergic symptoms: a prospective multi-center study

BACKGROUND

Allergy march refers to progression of allergic diseases from infantile food allergy to the development of asthma and allergic rhinitis (AR). Evidence come mostly from studies in European countries. This study aimed to investigate allergy march in Chinese children with infantile food protein allergy (FPA) with a special focus on the effect of different formula interventions.

METHODS

From 2008 to 2010, 153 infants diagnosed with FPA were recruited in five tertiary hospitals across China. They were randomly treated with amino-acid-based formula or soy-protein-based formula for a period of 3 months. Long-term follow-up was performed when they reached early school age, using questionnaires, physical examinations, and serum-specific immunoglobulin E.

RESULTS

The overall follow-up rate was 73.20%. In patients who reached their early school years, the prevalence of physician-diagnosed AR and asthma were 43.75% and 23.21%, respectively. Only 40% of the subjects remained positive for food sensitizations upon follow-up. Twenty-six subjects receiving aeroallergen screening tests in infancy all proved negative, but upon follow-up, 65.57% were sensitized to aeroallergens (P=0.005). No significant difference between the effects of amino-acid-based formula and soy-protein-based formula on children's allergy march was observed.

CONCLUSIONS

A high proportion (47.32%) of Chinese infants with early allergic symptoms developed respiratory allergies by their early school years. Most food-sensitized infants outgrew their condition several years later, but then aeroallergen sensitization often occurred. Amino-acid-based formula showed no advantages over soy protein-based formula with respect to arresting the allergy march.

Persistent asthma phenotype related with late-onset, high atopy, and low socioeconomic status in school-aged Korean children

BACKGROUND

Treatment guidelines for asthma have been established based on asthma severity; there are limitations in the identification of underlying pathophysiology and prediction of prognosis in heterogeneous phenotypes of asthma. Although the complex interactions between environmental and genetic factors affect the development and progression of asthma, studies on asthma phenotypes considering environmental factors are limited. This study aimed to identify asthma phenotypes using latent class analysis including environmental factors in school-age children.

METHODS

We included 235 children (6-8 years) with parent-reported, physician-diagnosed asthma from the Children's HEalth and Environmental Research (CHEER) study, which is a 4-year prospective follow-up study with 2-year intervals. At every survey, pulmonary function tests, methacholine challenge tests and blood tests with questionnaire were conducted.

RESULTS

Four asthma phenotypes were identified. Cluster 1 (22% of children) was characterized by high prevalence of atopy and mild symptoms; subjects in cluster 2 (17%) consisted of less atopy and normal lung function, but intermittent troublesome; cluster 3 (29%) experienced late-onset atopic troublesome asthma with decreased lung function in combination with low socioeconomic status; and cluster 4 was associated with early-onset and less-atopic infrequent asthma.

CONCLUSIONS

Late-onset, high atopy, and low socioeconomic status are associated with troublesome persistent asthma phenotype in school-age children. Environmental factors might be implicated in the clinical heterogeneity of asthma. Asthma phenotypes considering diverse factors might be more helpful in the identification of asthma pathogenesis and its prevention.

Anti-inflammatory therapies in atopic dermatitis

The pathogenesis of atopic dermatitis (AD) is multifactorial and complex. Consequently, clinical signs and symptoms vary strongly depending on individually relevant trigger factors and the stage of the disease. So far, treatment of AD was commonly limited to topical treatment or, in more severe cases, to systemic drugs mostly approved for other indications than AD. However, emerging data on new anti-inflammatory agents have been published in the recent years. As these new substances specifically focus on immune responses in AD, these are partially considered as possible 'breakthrough' in the treatment of AD. Therapeutic strategies of the future appear to be 'customized' for inflammation in AD as they target pro-inflammatory, highly relevant cytokines and cytokine receptors, such as IL-4Rα, IL-13, IL-31, and IL-17. Further innovative therapeutic approaches aim to block the function of relevant molecules such as thymic stromal lymphopoietin, chemoattractant-receptor homologous molecule expressed on Th2 lymphocytes (CRTh2), and phosphodiesterase (PDE)-4 inhibitors. Recently, anti-inflammatory effects in AD by antagonizing the histamine (H)-4 receptor have also been detected. Finally, specific immunotherapy is under further investigation as treatment option for AD patients with clinically relevant sensitization.

Targeting the T Helper 2 Inflammatory Axis in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects up to 25% of children and 10% of adults. The skin of patients with moderate to severe AD is characterized by significant barrier disruption and T helper 2 (Th2)-driven inflammation, which are thought to play a significant role in the pathogenesis of AD. Current management of AD is aimed at suppressing the inflammatory response and restoring the barrier function of the skin, reducing exacerbations, and preventing secondary skin infections. Combinations of treatment strategies are used to alleviate the symptoms of the disease; however, resolution is often temporary, and long-term usage of some of the medications for AD can be associated with significant side effects. Antibody therapies previously approved for other inflammatory diseases have been evaluated in patients with AD. Unfortunately, they have often failed to result in significant clinical improvement. Monoclonal antibodies and novel small molecules currently in development may provide more consistent benefit to patients with AD by specifically targeting the immune and molecular pathways important for the pathogenesis of AD. Here we review the state-of-the-art therapeutics targeting the Th2 axis in AD.