The genetics of atopic dermatitis: recent findings and future options

Protective effects of extracts from Acer truncatum leaves on SLS-induced HaCaT cells

Introduction:A. truncatum Bunge (Sapindaceae or formerly Aceraceae) is a tall deciduous tree native to China. Traditionally, the leaves of A. truncatum are decocted and used by Chinese Mongolians, Koreans, and Tibetans to treat skin itching, dry cracks, and other skin ailments, which indicates A. truncatum leaves may have a potential inhibitory effect on various skin inflammations.

Methods: To examine the protective effect against skin inflammations of A. truncatum leaf extract (ATLE), an in vitro dermatitis model was established using sodium dodecyl sulfate (SLS)-induced HaCaT cells. The anti-inflammatory effect of ATLE was evaluated by analyzing cell viability, apoptosis, reactive oxygen species (ROS), interleukin 6 (IL-6), and prostaglandin E2 (PGE2) levels.

Results: Orthogonal experiments showed that the pretreatment with ATLE can reduce the IL-6 levels, PGE2 levels, and apoptosis increased in SLS-stimulated HaCaT cells, which indicates that ATLE has positive efficacy for dermatitis. Furthermore, three flavonoid compounds kaempferol-3-O-α-L-rhamnoside, quercetin-3-O-α-L-rhamnopyranoside, kaempferol-3,7-di-O-α-L-rhamnoside, and 1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose (PGG) were isolated and identified. Among them, kaempferol-3,7-di-O-α-L-rhamnoside was isolated from this plant for the first time. These compounds have been proven to have an anti-inflammatory effect. They may contribute to the efficacy of A. truncatumin treating skin inflammation.

Discussion: The results revealed that ATLE has the potential to be used as an additive in various skin care products to prevent skin inflammations and may be incorporated in formulations for topical application as a therapeutic approach against dermatitis.

Targeting therapeutic approaches and highlighting the potential role of nanotechnology in atopic dermatitis

Atopic dermatitis is a chronic as well as widespread skin disease which has significant influence on the life attributes of affected people and their families. Systemic immunosuppressive drugs can be utilised for effective care of disease, although they are often prescribed for rigorous disruption or disease that is complicated to manage. Therefore, topical applications of corticosteroids are considered the primary pharmacologic therapies for atopic dermatitis, and research recommends that these medications might be helpful in preventing disease flare-ups. However, topical medicine administration to deeper layers of skin is challenging because of the skin anatomic barrier that restricts deeper drug permeation, and also due to barrier function abnormalities in atopic dermatitis skin, which might result in systemic drug absorption, provoking systemic consequences. Hence, effective management of atopic dermatitis needs new, effective, safe and targeted treatments. Therefore, nanotechnology-based topical therapeutics have attracted much interest nowadays because of their tendency to increase drug diffusion and bioavailability along with enormous drug targeting potential to affected cells, and, thereby, reducing the adverse effects of medications. In this review, we mention different symptoms of atopic dermatitis, and provide an overview of the different triggering factors causing atopic dermatitis, with emphasis on its epidemiology, pathophysiology, clinical features and diagnostic, and preventive measures. This review discusses existing therapeutics for treating atopic dermatitis, and the newer approaches as well as the current classical pharmacotherapy of atopic dermatitis against new nanoparticle skin delivery systems. This review has also briefly summarised the recent patents and clinical status of therapeutic modalities for atopic dermatitis.

Barrier Impairment and Type 2 Inflammation in Allergic Diseases: The Pediatric Perspective

Allergic diseases represent a global burden. Although the patho-physiological mechanisms are still poorly understood, epithelial barrier dysfunction and Th2 inflammatory response play a pivotal role. Barrier dysfunction, characterized by a loss of differentiation, reduced junctional integrity, and altered innate defence, underpins the pathogenesis of allergic diseases. Epithelial barrier impairment may be a potential therapeutic target for new treatment strategies Up now, monoclonal antibodies and new molecules targeting specific pathways of the immune response have been developed, and others are under investigation, both for adult and paediatric populations, which are affected by atopic dermatitis (AD), asthma, allergic rhinitis (AR), chronic rhinosinusitis with nasal polyps (CRSwNP), or eosinophilic esophagitis (EoE). In children affected by severe asthma biologics targeting IgE, IL-5 and against IL-4 and IL-13 receptors are already available, and they have also been applied in CRSwNP. In severe AD Dupilumab, a biologic which inhibits both IL-4 and IL-13, the most important cytokines involved in inflammation response, has been approved for treatment of patients over 12 years. While a biological approach has already shown great efficacy on the treatment of severe atopic conditions, early intervention to restore epithelial barrier integrity, and function may prevent the inflammatory response and the development of the atopic march.

Heterogeneity of Childhood Asthma in Korea: Cluster Analysis of the Korean Childhood Asthma Study Cohort

PURPOSE

Asthma is a heterogeneous airway disease occurring in children, and it has various clinical phenotypes. A clear differentiation of the clinical phenotypes can provide better asthma management and prediction of asthma prognosis. Little is currently known about asthma phenotypes in Korean children. This study was designed to identify asthma phenotypes in school-aged Korean children.

METHODS

This study enrolled 674 children with physician-diagnosed asthma from the Korean childhood Asthma Study (KAS) cohort. The physicians verified the relevant histories of asthma and comorbid diseases, as well as airway lability and hyper-responsiveness from the results of pulmonary function tests and bronchial provocation tests. Questionnaires regarding the participants' baseline characteristics, their environment and self-rating of asthma control were collected at the time of enrollment. Laboratory tests were performed to assess allergy and airway inflammation. Children with asthma were classified by hierarchical cluster analysis.

RESULTS

Of the 674 patients enrolled from the KAS cohort, 447 were included in the cluster analysis. Cluster analysis of these 447 children revealed 4 asthma phenotypes: cluster 1 (n = 216, 48.3%) which was characterized by male-dominant atopic asthma; cluster 2 (n = 79, 17.7%) which was characterized by early-onset atopic asthma with atopic dermatitis; cluster 3 (n = 47, 10.5%) which was characterized by puberty-onset, female-dominant atopic asthma with the low lung function; and cluster 4 (n = 105, 23.5%) which was characterized by early-onset, non-atopic dominant asthma.

CONCLUSIONS

The asthma phenotypes among Korean children can be classified into 4 distinct clusters. Long-term follow-up with these phenotypes will be needed to define their prognosis and response to treatment.

Genetic, Clinical, and Environmental Factors Associated With Persistent Atopic Dermatitis in Childhood

Importance

Knowledge about factors associated with persistence of atopic dermatitis (AD) during childhood is sparse.

Objective

To explore heritable, environmental, and clinical factors associated with persistent AD based on 13 years' follow-up of an at-risk birth cohort.

Design, Setting, and Participants

In the Copenhagen Prospective Study on Asthma in Childhood 2000 (COPSAC2000) clinical birth cohort study, 411 children born to mothers with asthma were followed up until the age of 13 years at a clinical research unit in Copenhagen, Denmark, from August 1998 to June 2015. Atopic dermatitis was diagnosed prospectively during close clinical follow-up according to the criteria of Hanifin and Rajka. Data were gathered on parental history, social circumstances, and environmental factors through parent interviews. The cohort was followed up with biannual visits to the clinic until the age of 7 years and were seen again at age 13 years. Data were analyzed from August 2015 to January 2018.

Main Outcomes and Measures

Atopic dermatitis was diagnosed using Hanifin and Rajka major and minor criteria, and severity was determined by Scoring Atopic Dermatitis (SCORAD) index, with possible scores from 0 to 83, with higher scores indicating more severe AD.

Results

Of the 411 children in the cohort, 203 (49.4%) were male and 186 (45.3%) were diagnosed with AD before the age of 13 years; 40 of 166 children (24.1%) had persistent AD at the age of 13 years, and 126 (76.0%) experienced remission. Factors associated with persistent AD to age 13 years included heritability, environmental exposures, asthma and allergic sensitization, clinical presentation at the time of diagnosis, the composition of Hanifin and Rajka diagnostic minor criteria, and AD severity according to SCORAD. A higher AD genetic risk score was associated with an increased the risk for persistent AD (multivariable odds ratio [OR], 1.8; 95% CI, 1.1-2.9; P = .02), together with paternal asthma (multivariable OR, 3.7; 95% CI, 1.2-11.5; P = .02); paternal AD (multivariable OR, 6.2; 95% CI, 1.17-23.2; P = .007), and higher social circumstances (multivariable OR, 1.6; 95% CI, 1.0-2.5; P = .05). Particular clinical presentations at time of diagnosis were also associated with specific minor criteria of Hanifin and Rajka (Dennie-Morgan and anterior neck folds, white dermographism, intolerance to wool, itching when sweating, tendency to skin infection, food intolerance, and food allergy) (OR, 2.6; 95% CI, 1.1-6.2; P = .03) as well as increased severity at diagnosis (OR, 1.1; 95% CI, 1.0-1.1; P = .007).

Conclusions and Relevance

In a birth cohort of children at risk for asthma who received close clinical follow-up to age 13 years, known genetic AD risk variants, paternal asthma and AD, high social circumstances, diagnostic minor criteria, and disease severity at onset were associated with persistent AD at age 13 years. These findings may be applied in clinical practice to evaluate the likely disease course for individual patients.

Periostin in the pathogenesis of skin diseases

Skin is an organ that is susceptible to damage by external injury, chronic inflammation, and autoimmunity. Tissue damage causes alterations in both the configuration and type of cells in lesional skin. This phenomenon, called tissue remodeling, is a universal biological response elicited by programmed cell death, inflammation, immune disorders, and tumorigenic, tumor proliferative, and cytoreductive activity. In this process, changes in the components of the extracellular matrix are required to provide an environment that facilitates tissue remodeling. Among these extracellular matrix components, periostin, a glycoprotein that is predominantly secreted from dermal fibroblasts, has attracted attention. Periostin localizes in the papillary dermis of normal skin, and is aberrantly expressed in the dermis of lesional skin in atopic dermatitis, scar, systemic/limited scleroderma, melanoma, cutaneous T cell lymphoma, and skin damage caused by allergic/autoimmune responses. Periostin induces processes that result in the development of dermal fibrosis, and activate or protract the immune response. The aim of this review was to summarize recent knowledge of the role of periostin in the pathogenesis of dermatoses, and to explore whether periostin is a potential therapeutic target for skin diseases.

Clinical Features of Adult/Adolescent Atopic Dermatitis and Chinese Criteria for Atopic Dermatitis

Background:

Atopic dermatitis (AD) is an inflammatory skin disease characterized by chronic recurrent dermatitis with profound itching. Most patients have personal and/or family history of atopic diseases. Several criteria have been proposed for the diagnosis of AD. Although the clinical features of childhood AD have been widely studied, there has been less large-scale study on adult/adolescent AD. The aim of this study was to investigate the clinical features of adult/adolescent patients with chronic symmetrical eczema/AD and to propose Chinese diagnostic criteria for adult/adolescent AD.

Methods:

A hospital-based study was performed. Forty-two dermatological centers participated in this study. Adult and adolescent patients (12 years and over) with chronic symmetrical eczema or AD were included in this study. Questionnaires were completed by both patients and investigators. The valid questionnaires were analyzed using EpiData 3.1 and SPSS 17.0 software.

Results:

A total of 2662 valid questionnaires were collected (1369 male and 1293 female). Of all 2662 patients, 2062 (77.5%) patients had the disease after 12 years old, while only 600 (22.5%) patients had the disease before 12 years old, suggesting late-onset eczema/AD is common. Two thousand one hundred and thirty-nine (80.4%) patients had the disease for more than 6 months. One thousand one hundred and forty-four (43.0%) patients had a personal and/or family history of atopic diseases. One thousand five hundred and forty-eight (58.2%) patients had an elevated total serum IgE and/or eosinophilia and/or positive allergen-specific IgE. Based on these clinical and laboratory features, we proposed Chinese criteria for adult/adolescent AD. Of all 2662 patients, 60.3% were satisfied with our criteria, while only 48.2% satisfied with Hanifin Rajka criteria and 32.7% satisfied with Williams criteria, suggesting a good sensitivity of our criteria in adult/adolescent AD patients.

Conclusion:

Late-onset of eczema or AD is common. The clinical manifestations of AD are heterogeneous. We have proposed Chinese diagnostic criteria for adolescent and adult AD, which are simple and sensitive for diagnosis of adult/adolescent AD.

Review of Systemic Treatment Options for Adult Atopic Dermatitis

Background:

Atopic dermatitis (AD) is a chronic, pruritic inflammatory skin disease resulting from defects in skin barrier and aberrant immune responses. AD significantly affects the quality of life. Not all patients respond to topical therapies, and often systemic therapy is required to control the disease.

Objective:

To review the treatment options for adult AD patients including those options for patients who do not respond adequately or have contraindications to oral systemic therapy.

Methods:

A working group of clinicians with experience managing AD was convened to review the current literature on treatment options for adult AD patients. This review is based on the best available evidence from a published systematic review and an additional literature search.

Results:

Current treatments for AD are reviewed, including options for adult AD patients who do not respond or have contraindications to current systemic therapies. A new approach with targeted therapies is reviewed based on best available evidence.

Conclusion:

Many AD patients respond satisfactorily to topical or systemic treatments, but for those patients who do not respond or have contraindications, new biologic agents appear to be promising therapies.

Probiotics and Atopic Dermatitis: An Overview

Atopic dermatitis (AD) is a common, recurrent, chronic inflammatory skin disease that is a cause of considerable economic and social burden. Its prevalence varies substantially among different countries with an incidence rate proclaimed to reach up to 20% of children in developed countries and continues to escalate in developing nations. This increased rate of incidence has changed the focus of research on AD toward epidemiology, prevention, and treatment. The effects of probiotics in the prevention and treatment of AD remain elusive. However, evidence from different research groups show that probiotics could have positive effect on AD treatment, if any, that depend on multiple factors, such as specific probiotic strains, time of administration (onset time), duration of exposure, and dosage. However, till date we still lack strong evidence to advocate the use of probiotics in the treatment of AD, and questions remain to be answered considering its clinical use in future. Based on updated information, the processes that facilitate the development of AD and the topic of the administration of probiotics are addressed in this review.

Expression and function of histamine and its receptors in atopic dermatitis

Background

Atopic dermatitis constitutes a most burdensome chronic inflammatory skin disease. Standard treatment is cumbersome and often targets its main symptom, pruritus, only insufficiently.

Findings

Recent advances in our understanding of the role of histamine and its four receptors suggest new approaches which target the histamine receptors alone or as combination therapies to more efficiently combat pruritus and inflammation in atopic dermatitis.

Conclusions

With this review, we provide an overview on histamine and the expression of its four receptors on skin resident and nonresident cells. Furthermore, we summarize recent studies which suggest anti-histamine therapy to efficiently combat pruritus and inflammation in atopic dermatitis and discuss possible approaches to incorporate these findings into more effective treatment strategies for atopic dermatitis in childhood.

Molecular biology of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific genetic and immunological mechanisms. The rapid development of new techniques in molecular biology had ushered in new discoveries on the role of cytokines, chemokines, and immune cells in the pathogenesis of AD. New polymorphisms of AD are continually being reported in different populations. The physical and immunological barrier of normal intact skin is an important part of the innate immune system that protects the host against microbials and allergens that are associated with AD. Defects in the filaggrin gene FLG may play a role in facilitating exposure to allergens and microbial pathogens, which may induce Th2 polarization. Meanwhile, Th22 cells also play roles in skin barrier impairment through IL-22, and AD is often considered to be a Th2/Th22-dominant allergic disease. Mast cells and eosinophils are also involved in the inflammation via Th2 cytokines. Release of pruritogenic substances by mast cells induces scratching that further disrupts the skin barrier. Th1 and Th17 cells are mainly involved in chronic phase of AD. Keratinocytes also produce proinflammatory cytokines such as thymic stromal lymphopoietin (TSLP), which can further affect Th cells balance. The immunological characteristics of AD may differ for various endotypes and phenotypes. Due to the heterogeneity of the disease, and the redundancies of these mechanisms, our knowledge of the pathophysiology of the disease is still incomplete, which is reflected by the absence of a cure for the disease.

Barrier-restoring therapies in atopic dermatitis: current approaches and future perspectives

Atopic dermatitis is a multifactorial, chronic relapsing, inflammatory disease, characterized by xerosis, eczematous lesions, and pruritus. The latter usually leads to an “itch-scratch” cycle that may compromise the epidermal barrier. Skin barrier abnormalities in atopic dermatitis may result from mutations in the gene encoding for filaggrin, which plays an important role in the formation of cornified cytosol. Barrier abnormalities render the skin more permeable to irritants, allergens, and microorganisms. Treatment of atopic dermatitis must be directed to control the itching, suppress the inflammation, and restore the skin barrier. Emollients, both creams and ointments, improve the barrier function of stratum corneum by providing it with water and lipids. Studies on atopic dermatitis and barrier repair treatment show that adequate lipid replacement therapy reduces the inflammation and restores epidermal function. Efforts directed to develop immunomodulators that interfere with cytokine-induced skin barrier dysfunction, provide a promising strategy for treatment of atopic dermatitis. Moreover, an impressive proliferation of more than 80 clinical studies focusing on topical treatments in atopic dermatitis led to growing expectations for better therapies.

Dermal fibroblasts from acute inflamed atopic dermatitis lesions display increased eotaxin/CCL11 responsiveness to interleukin-4 stimulation

BACKGROUND

The presence of eosinophils and/or eosinophil-derived products in the dermis is characteristic for involved skin of patients with atopic dermatitis and contributes to the observed tissue injury. CCL11 is a potent chemoattractant and activator of human eosinophils and interleukin (IL)-4 is a potent inducer of CCL11 expression in dermal fibroblasts.

OBJECTIVES

As increased fibroblast CCL11 expression may explain eosinophilic infiltration of involved skin areas in atopic dermatitis, we asked whether dermal fibroblasts from atopic patients differ from fibroblasts of healthy individuals in their ability to express CCL11.

METHODS

We compared IL-4-induced CCL11 mRNA expression using reverse transcription-polymerase chain reaction from cultured dermal fibroblasts derived from biopsies of chronic lesional and acute lesional atopic skin as well as from skin biopsies derived from normal skin of healthy donors.

RESULTS

Considerable variability in IL-4-induced relative CCL11 mRNA expression was detected in fibroblasts derived from biopsies of different individuals. The lowest median IL-4 concentration inducing half maximal CCL11 mRNA expression (EC(50)) was found in fibroblasts derived from acute inflamed atopic lesions.

CONCLUSIONS

Inducibility of CCL11 in dermal fibroblasts upon stimulation with Th2 cytokines explains the tissue eosinophilia observed in the presence of Th2 cytokines and the localization of eosinophils to the dermis. Decreased EC(50) values of IL-4-induced CCL11 expression in fibroblasts from acute inflamed atopic skin lesions indicates increased IL-4 responsiveness in these lesions and further substantiates the special role for IL-4-induced dermal fibroblast CCL11 expression in acute lesions. Variable CCL11 expression in fibroblasts from different patients with atopic dermatitis indicates heterogeneity of factors determining atopic phenotype in atopic dermatitis.

Glutamine-enriched enteral nutrition in very low birthweight infants and allergic and infectious diseases at 6 years of age

In a previous randomised controlled trial, we found that glutamine-enriched enteral nutrition in 102 very low birthweight (VLBW) infants decreased both the incidence of serious infections in the neonatal period and the risk of atopic dermatitis during the first year of life. We hypothesised that glutamine-enriched enteral nutrition in VLBW infants in the neonatal period influences the risk of allergic and infectious disease at 6 years of age. Eighty-eight of the 102 infants were eligible for the follow-up study (13 died, 1 chromosomal abnormality). Doctor-diagnosed allergic and infectious diseases were assessed by means of validated questionnaires. The association between glutamine-enriched enteral nutrition in the neonatal period and allergic and infectious diseases at 6 years of age was based on univariable and multivariable logistic regression analyses. Seventy-six of the 89 (85%) infants participated, 38 in the original glutamine-supplemented group and 38 in the control group. After adjustment, we found a decreased risk of atopic dermatitis in the glutamine-supplemented group: adjusted odds ratio (aOR) 0.23 [95% CI 0.06, 0.95]. No association between glutamine supplementation and hay fever, recurrent wheeze and asthma was found. A decreased risk of gastrointestinal tract infections was found in the glutamine-supplemented group (aOR) 0.10 [95% CI 0.01, 0.93], but there was no association with upper respiratory, lower respiratory or urinary tract infections. We concluded that glutamine-enriched enteral nutrition in the neonatal period in VLBW infants decreased the risk of atopic dermatitis and gastrointestinal tract infections at 6 years of age.

Glutathione S-transferase M1 (GSTM1) polymorphism is associated with atopic dermatitis susceptibility in a Korean population

Atopic dermatitis (AD) is a chronic pruritic skin condition affecting as much as 15% of children in industrialized countries. While the underlying pathophysiology of AD is not entirely understood, several studies have suggested that AD may mediated by oxidative stress. Glutathione S-transferases (GSTs) are a class of polymorphic enzymes that function to protect against oxidative stress. To identify any possible associations between GSTs polymorphisms and AD susceptibility, the prevalence of two specific polymorphisms -GSTM1 and GSTT1 (homozygous deletion vs. undeleted) - were quantified by multiplex PCR in 145 patients with AD and 267 healthy controls. In individuals with AD, GSTM1/GSTT1 polymorphisms were compared with family history of AD, age of disease onset, disease severity [per SCORing Atopic Dermatitis (SCORAD)], serum IgE level and presence of other allergic diseases. While the GSTM1-null genotype was found to be significantly associated with AD (P = 0.033, OR = 1.579, 95% CI = 1.037-2.403), the correlation between the GSTT1-null genotype and AD did not reach statistical significance (P = 0.577, OR = 1.125, 95% CI = 0.744-1.702). The GSTM1-null genotype was also found to be significantly associated with a childhood onset of AD, the absence of other allergic diseases, and a family history of AD. In combination, these results suggest that GSTM1 is associated with AD susceptibility in Korean subjects.

What's new in atopic eczema?

IMPORTANCE OF THE FIELD

Atopic eczema (AE) is a chronic relapsing inflammatory skin condition and one of the most common, potentially debilitating diseases with increasing incidence.

AREAS COVERED IN THIS REVIEW

The complex etiology of AE with multiple systemic and local immunologic and inflammatory responses and interactions between susceptibility genes and environmental factors leading to defects in skin barrier function and eczematous skin lesions is presented. Knowledge of pathogenesis is important for understanding the more innovative treatment approaches discussed.

WHAT THE READER WILL GAIN

Basic therapy consists of hydrating topical treatment and avoidance of specific and unspecific provocation factors. For acute eczematous skin lesions, anti-inflammatory treatment consists mainly of topical glucocorticoids and topical calcineurin inhibitors (tacrolimus and pimecrolimus). Microbial colonization and superinfection may induce skin exacerbation, which can be treated by either topical or systemic antimicrobial treatment. Systemic anti-inflammatory therapy is limited to severe cases and consists of systemic steroids, cyclosporine A or mycophenolate mofetil. Novel anti-inflammatory concepts that go beyond corticosteroids are in the early phases of development. There are targeted therapeutic approaches, such as cytokine and chemokine modulators and it remains to be investigated how effective they will be and what side effects they may carry.

TAKE HOME MESSAGE

Existing treatment modalities such as barrier repair therapy, topical immunosuppressive agents, antiseptic treatment as well as systemic treatment options are discussed. The review aims to summarize the most recent findings of more innovative treatment approaches such as modulation of cytokines or chemokines, modulation of T-cell responses or anti-IgE therapy.

Does eczema lead to asthma?

The nature of the relationship between eczema, asthma, and allergic rhinitis has been controversial. It has been commonly held that these disorders, while sharing genetic and environmental risk factors, are unrelated disorders that may develop sequentially along an atopic pathway. Conversely, the link between eczema and these later-onset respiratory disorders may be causal. This review examines the relationship between eczema, asthma, and allergic rhinitis in the context of the atopic march, the skin barrier, and recent developments in eczema genetics; and we propose that the relationship is causal. We describe a plausible biological pathway with eczema as the first step in a progressive atopic march that over time leads to asthma and/or allergic rhinitis. Such a pathway has implications for our understanding of these disorders and steps that might be made to prevent the development of asthma in particular. We propose that intervention studies in eczema should be conducted to confirm or refute this causal relationship. Such studies may materially improve the quality of life of eczema patients and will have important public health benefits if the interventions lead to a reduction in the burden of asthma.

Linkage of atopic dermatitis to chromosomes 4q22, 3p24 and 3q21

Atopic dermatitis (AD) is a common, itchy skin disease of complex inheritance characterized by dermal and epidermal inflammation. The heritability is considerable and well documented. To date, four genome scans have examined the AD phenotype, showing replicated linkage at 3p26-22, 3q13-21 and 18q11-21. Our previous AD scan showed evidence of linkage to loci at 3p and 18q, and furthermore at 4p15-14. In order to further investigate the genetic basis of AD, we collected and analysed a new Danish family sample consisting of 130 AD sib pair families (555 individuals including 295 children with AD). AD was diagnosed after clinical examination, AD severity was scored and specific IgE was determined. A linkage scan of chromosome 3, 4 and 18 was performed using 91 microsatellite markers. Linkage analyses were performed of dichotomous phenotypes and semi-quantitative traits including the AD severity score. We analysed the novel AD sample alone and together with the previously examined sample. AD severity showed a maximum Z-score of 3.7 at 4q22.1 suggesting the localization of a novel gene for AD severity. A maximum MOD score of 4.6 was obtained at 3p24 for the AD phenotype, providing the first significant linkage of AD at this locus. A maximum MLS score of 3.3 was obtained at 3q21 for IgE-associated AD, and evidence of linkage was also obtained at 3p22.2-21.31, 3q13, 4q35, and 18q12. The results presented should provide a firm basis for gene-targeting studies of AD and related disorders.

Emerging drugs for atopic dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease, affecting 10-20% of children and 2% of adults worldwide. Preventive treatment of AD consists of daily skin hydration and emollient therapy; but the majority of patients still require symptomatic treatment with topical corticosteroids and/or topical calcineurin inhibitors, both of which may be associated with potential long-term side effects. With increasing evidence supporting the role of skin barrier defects in the pathogenesis of AD, there is also a parallel increase in medications that claim to assist barrier repair. The current review discusses some exciting results with these medications, as well as the challenges that lie ahead of them. While barrier repair treatments offer some promise, there continues to be a need for safer anti-inflammatory medications. Some of these medications under investigation are phosphodiesterase-4 inhibitors, urocanic acid oxidation products and IL-4/IL-13 receptor blockers. The review also discusses anti-staphylococcal treatments including nanocrystalline silver cream, silver and antimicrobial-coated fabrics, and anti-itch treatments including mu-opiod receptor antagonists, chymase inhibitors and cannabinoid receptor agonists. These medications may become an integral part of AD therapy.

The prevalence, characteristics of and risk factors for eczema in Belgian schoolchildren

Childhood eczema is common in infants, but its nature and extent during later childhood remains unclear. In this cross-sectional study we examined the prevalence and characteristics of eczema in an unbiased community population of 2,021 Belgian schoolchildren, aged 3.4 to 14.8 years with skin prick testing and parental questionnaires. Our study identified an eczema prevalence of 23.3% and a considerable allergic comorbidity, mainly in sensitized children. The reported prevalence of eczema in infancy was 18.5% and for current eczema 11.6%. The overall sensitization rate (33.2%) as well as sensitization rates for the individual allergens were significantly higher in children with "eczema ever." Sensitization to Dermatophagoides pteronyssinus (19.6%), mixed grass pollen (15.1%), and cat (9.1%) were most common. Until the age of 6 years, boys with eczema were significantly more sensitized than girls (p = 0.007). Children with both eczema in infancy and current eczema show a tendency to be more sensitized than children with eczema in infancy only or current eczema only, but significance was only noted for a few individual allergens. Analysis of factors associated with eczema revealed a predominantly atopic profile characterized by family or personal history of allergy. Breastfeeding and environmental factors seemed to assume little relevance except for a protective effect of prematurity and having a dog at birth.

New insights into the mechanism and management of allergic diseases: atopic dermatitis

Rapidly increasing knowledge on the complex background of atopic dermatitis (AD) on the genetic, immunological and environmental level in combination with the continuous improvement in our diagnostic options has initiated an ongoing discussion on factors, which primarily promote the disease on one hand and mechanisms which emerge rather secondarily as a consequence of disease-specific modifications, on the other hand. Beside a sustained search for reliable and meaningful diagnostic tools for elicitors of the disease, novel therapeutic approaches are required, as most of the treatments of AD are limited to symptomatic therapies. In contrast, therapeutic approaches selectively regulating aberrant pathophysiological mechanisms in AD itself would be much more effective and promising.

Cellular and molecular mechanisms in atopic dermatitis

Atopic dermatitis (AD) is a pruritic inflammatory skin disease associated with a personal or family history of allergy. The prevalence of AD is on the rise and estimated at approximately 17% in the USA. The fundamental lesion in AD is a defective skin barrier that results in dry itchy skin, and is aggravated by mechanical injury inflicted by scratching. This allows entry of antigens via the skin and creates a milieu that shapes the immune response to these antigens. This review discusses recent advances in our understanding of the abnormal skin barrier in AD, namely abnormalities in epidermal structural proteins, such as filaggrin, mutated in approximately 15% of patients with AD, epidermal lipids, and epidermal proteases and protease inhibitors. The review also dissects, based on information from mouse models of AD, the contributions of the innate and adaptive immune system to the pathogenesis of AD, including the effect of mechanical skin injury on the polarization of skin dendritic cells, mediated by keratinocyte-derived cytokines such as thymic stromal lymphopoietin (TSLP), IL-6, and IL-1, that results in a Th2-dominated immune response with a Th17 component in acute AD skin lesions and the progressive conversion to a Th1-dominated response in chronic AD skin lesions. Finally, we discuss the mechanisms of susceptibility of AD skin lesions to microbial infections and the role of microbial products in exacerbating skin inflammation in AD. Based on this information, we discuss current and future therapy of this common disease.

Atopic dermatitis: a review of recent advances in the field

Atopic dermatitis is increasing in prevalence and currently affects 15–30% of children in urban areas. Immune dysregulation and an impaired epidermal barrier are important factors in the pathogenesis of this disease. Pruritus and a chronic relapsing remitting course are hallmarks of the disorder, and sleep disturbance can occur in both the patient and family. Preventive interventions include exclusive breastfeeding in the first 4 months of life and withholding solid foods for 6 months. The avoidance of irritants and the use of emollients decrease flares. Topical corticosteroids remain the mainstay of therapy, and should be judiciously utilized. Excessive and inappropriate use must be avoided, as well as ‘steroid phobia’. The topical calcineurin inhibitors can be useful adjuncts. Systemic therapies are available for severe disease, but carry risks of adverse effects.

Variation in genes encoding eosinophil granule proteins in atopic dermatitis patients from Germany

Background

Atopic dermatitis (AD) is believed to result from complex interactions between genetic and environmental factors. A main feature of AD as well as other allergic disorders is serum and tissue eosinophilia. Human eosinophils contain high amounts of cationic granule proteins, including eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN), eosinophil peroxidase (EPO) and major basic protein (MBP). Recently, variation in genes encoding eosinophil granule proteins has been suggested to play a role in the pathogenesis of allergic disorders. We therefore genotyped selected single nucleotide polymorphisms within the ECP, EDN, EPO and MBP genes in a cohort of 361 German AD patients and 325 healthy controls.

Results

Genotype and allele frequencies did not differ between patients and controls for all polymorphisms investigated in this study. Haplotype analysis did not reveal any additional information.

Conclusion

We did not find evidence to support an influence of variation in genes encoding eosinophil granule proteins for AD pathogenesis in this German cohort.

No evidence of an association between polymorphisms in the IRAK-M gene and atopic dermatitis in a German cohort

Atopic dermatitis (AD) is a chronic inflammatory skin disease which affects up to 10-15% of the human population in industrialized countries. A complex interaction of genetic and environmental factors is suggested to be involved in the pathogenesis of this disease. Activation of the innate immune system via toll-like receptors (TLRs) might play a role in this respect. Interleukin-1 receptor associated kinase M (IRAK-M) negatively regulates TLR signalling and inflammation. Recently, the IRAK-M gene was identified to confer linkage to asthma on chromosome 12q13-24 in a Sardinian population, and variation within the IRAK-M gene was associated with early-onset persistent asthma in Sardinian and Italian cohorts. In order to evaluate the possible role of polymorphisms in the IRAK-M gene in the pathogenesis of AD, we investigated six single nucleotide polymorphisms (SNPs) in this gene in a German AD case-control study. Unrelated AD patients (n=361) and healthy controls (n=325) were studied genetically using PCR-coupled methods. Analysis of single SNPs and haplotypes did not reveal a significant association between polymorphisms in the IRAK-M gene and AD in this cohort.

Auf1/Hnrnpd-deficient mice develop pruritic inflammatory skin disease

Mice lacking heterogenous nuclear ribonuclear protein D (Hnrnpd), also known as Auf1, a regulator of inflammatory cytokine mRNA stability, develop chronic dermatitis with age that is characterized by pruritus and excoriations. Histological analysis showed marked epidermal acanthosis and spongiosis, neovascularization, and elevated number of inflammatory cells, including T cells, macrophages, neutrophils, mast cells, and eosinophils. Hnrnpd-deficient (Hnrnpd(tm1Rjsc)) mice with dermatitis display elevated serum IgE levels. Lesions in Hnrnpd(tm1Rjsc) mice were associated with a shift towards a Th(2) immune environment. Evaluation of T-cell-mediated skin inflammation by assaying contact hypersensitivity indicated an increased response in Hnrnpd(tm1Rjsc) mice. T cells and macrophages from Hnrnpd(tm1Rjsc) mice demonstrate a number of abnormalities associated with dermatitis, including increased IL2, tumor-necrosis factor-alpha (TNFalpha), and IL1beta production. Finally, many features of spontaneous dermatitis could be recapitulated in experimentally induced lesions by subcutaneous injection of CCL27 and TNF in unaffected Hnrnpd(tm1Rjsc) mice. Collectively, these data highlight the importance of HNRNPD and proper regulation of mRNA stability in the intricate processes of leukocyte recruitment and inflammatory activation within the skin.

Gene Expression Profiling of Lichen Planus Reflects CXCL9+-Mediated Inflammation and Distinguishes this Disease from Atopic Dermatitis and Psoriasis

Here, we present data of a gene expression profiling approach to apply the diagnostic value and pathological significance of this method in different inflammatory skin diseases, using whole skin biopsies. Initially, SAGE was performed to identify frequent tags differentially expressed in various skin diseases. On the basis of these results, a new skin pathology-oriented PIQOR microarray was designed. Lichen planus (LP) was chosen as a model disease to evaluate this system. Controls included healthy skin, atopic dermatitis (AD), and psoriasis (Pso). Gene expression analyses using the topic-defined microarray followed by unclassified clustering was able to discriminate LP from AD and Pso. Genes significantly expressed in LP included type I IFN inducible genes and a specific chemokine expression pattern. The CXCR3 ligand, CXCL9, was the most significant marker for LP. In situ hybridization and immunohistochemistry confirmed the results and revealed that keratinocytes are type I IFN producers in LP skin lesions. Our results show that gene expression profiling using a skin-specific microarray is a reliable method to identify patients with LP in the chosen context and reflect recent models concerning the pathogenesis of this disease. Gene expression profiling might complement the diagnostic spectrum in dermatology and may provide new pathogenetic insights.

Development of atopic dermatitis in mice transgenic for human apolipoprotein C1

Mice with transgenic expression of human apolipoprotein C1 (APOC1) in liver and skin have strongly increased serum levels of cholesterol, triglycerides, and free fatty acids, indicative of a disturbed lipid metabolism. Importantly, these mice display a disturbed skin barrier function, evident from increased transepidermal water loss, and spontaneously develop symptoms of dermatitis including scaling, lichenification, excoriations, and pruritus. Histological analysis shows increased epidermal thickening and spongiosis in conjunction with elevated numbers of inflammatory cells (eosinophils, neutrophils, mast cells, macrophages, and CD4+ T cells) in the dermis. In addition, affected mice have increased serum levels of IgE and show abundant IgE(+) mast cells in the dermis. Partial inhibition of disease could be achieved by restoration of the skin barrier function with topical application of a lipophilic ointment. Furthermore, the development of atopic dermatitis in these mice was suppressed by corticosteroid treatment. These findings in APOC1(+/+) mice underscore the role of skin barrier integrity in the pathogenesis of atopic dermatitis.

Polymorphisms in NACHT-LRR (NLR) genes in atopic dermatitis

Atopic dermatitis (AD) is a chronic skin disease affecting up to 15% of children in industrialized countries. AD belongs to the group of atopic disorders characterized by excessive immune reactions to ubiquitous antigens. Complex interactions between genetic and environmental factors have been suggested for atopic disorders. Dysregulation of the innate immune system appears crucial for the pathogenesis of AD. The NACHT-LRRs (NLRs) represent a group of innate immune receptors with special relevance for inflammatory processes. In order to investigate the role of variation in NLR genes for AD, we genotyped 23 single nucleotide polymorphisms (SNPs) in seven selected NLR genes (CARD4, CARD15, CARD12, NALP1, NALP3, NALP12, MHC2TA) in 392 AD patients and 297 controls by restriction enzyme digestion or TaqMan assays. Single-SNP analysis demonstrated significant associations of the CARD15_R702W variation and the NALP12_In9 T-allele with AD (P = 0.008 and P = 0.03, resp.; insignificant after Bonferroni correction). In the CARD4 gene, a rare haplotype was more frequent in AD patients than in controls. Interactions between all pairs of SNPs in the seven genes were analysed by logistic regression. Significant interactions comprised SNPs in the CARD4 gene (CARD4_In1 and CARD4_Ex6, P = 6.56 x 10(-7); CARD4_Prom und CARD4_Ex6, P = 2.45 x 10(-4)) and promoter polymorphisms in the CARD12 and NALP1 genes (P = 4.31 x 10(-4)). In conclusion, variation in individual genes from the NLR family as well as interactions within this group of innate immune receptor genes could play a role in AD pathogenesis. Investigations in other populations and functional studies are warranted to clarify contributions of NLR variation for this frequent skin disease.