Filaggrin mutations associated with skin and allergic diseases

Pyrrolidone carboxylic acid levels or caspase-14 expression in the corneocytes of lesional skin correlates with clinical severity, skin barrier function and lesional inflammation in atopic dermatitis

BACKGROUND

Dry skin in atopic dermatitis (AD) mainly results from barrier impairment due to deficiency of ceramide and natural moisturizing factors including pyrrolidone carboxylic acid (PCA) in stratum corneum (SC). Caspase-14 cleaves filaggrin monomers to free amino acids and their derivatives such as PCA, contributing natural moisturizing factors. Cytokines in the corneocytes represent cutaneous inflammation severity of AD patients.

OBJECT

To analyze the correlations of PCA, caspase-14 and cytokines in corneocytes with clinical severity, barrier function and skin inflammation, those were quantitated.

METHODS

A total of 73 persons were enrolled: 21 patients with mild AD, 21 with moderate-to-severe AD, 13 with X-linked ichthyosis (XLI) as a negative control for filaggrin gene (FLG) mutation, and 18 healthy controls. Skin barrier functions such as basal transepidermal water loss (TEWL), stratum corneum (SC) hydration and skin surface pH were measured. To collect corneocytes, stripping with D-squame discs was done on lesional and non-lesional skin. And then PCA was isolated from D-squame discs and quantitated by LC-MS/MS. Cytokine assays were performed.

RESULTS

The quantity of PCA and caspase-14 was decreased in inflammatory lesions compared to non-lesion in AD patients. And the amounts of PCA and caspase-14 in the lesion of AD patients correlated with clinical severity as determined by eczema area and severity index score and the skin barrier functions. Also, the expressions of TNF-α and IL-13 inversely correlated with PCA quantity.

CONCLUSION

The quantity of PCA or caspase-14 in the corneocytes of the lesional skin of AD patients reflects the clinical severity, skin barrier function and the degree of lesional inflammation.

Association of filaggrin variants with asthma and rhinitis: is eczema or allergic sensitization status an effect modifier?

BACKGROUND

Associations of variants of the filaggrin gene, i.e. FLG with asthma and rhinitis have been shown to be modulated by eczema status. However, it is unknown whether allergic sensitization status modifies this association. The aim of this study was to determine whether FLG variants need eczema and/or allergic sensitization as a necessary component to execute adverse effects on coexisting and subsequent asthma and rhinitis.

METHODS

In the Isle of Wight birth cohort, repeated measurements of asthma, rhinitis, eczema and allergic sensitization (documented by skin-prick tests) were taken in 1,456 children at the ages of 1, 2, 4, 10 and 18 years. Filaggrin haploinsufficiency was defined as having at least the minor allele of R501X, 2282del4 or S3247X variants. log-binomial regression models were used to test associations and statistical interactions.

RESULTS

FLG variants increased the risk of asthma [risk ratio (RR) 1.39, 95% confidence interval (CI) 1.06-1.80] and rhinitis (RR 1.37, 95% CI 1.16-1.63). In the delayed-effects models, 'FLG variants plus allergic sensitization' and 'FLG variants plus eczema' increased the risk of subsequent asthma by 4.93-fold (95% CI 3.61-6.71) and 3.33-fold (95% CI 2.45-4.51), respectively, during the first 18 years of life. In contrast, neither eczema nor allergic sensitization in combination with FLG variants increased the risk of later rhinitis.

CONCLUSIONS

Allergic sensitization and eczema modulated the association between FLG variants and asthma but not rhinitis. Our results imply that the mechanisms and pathways through which FLG variants predispose to an increased risk of asthma and rhinitis may be different.

Regulation of the dynamic chromatin architecture of the epidermal differentiation complex is mediated by a c-Jun/AP-1-modulated enhancer

The epidermal differentiation complex (EDC) locus comprises a syntenic and linear cluster of genes whose concomitant expression is a hallmark feature of differentiation in the developing skin epidermis. Many of the EDC proteins are cross-linked together to form the cornified envelope, an essential and discrete unit of the mammalian skin barrier. The mechanism underlying coordinate transcriptional activation of the EDC is unknown. Within the human EDC, we identified an epidermal-specific regulatory enhancer, 923, which responded to the developmental and spatiotemporal cues at the onset of epidermal differentiation in the mouse embryo. Comparative chromosomal conformation capture assays in proliferating and differentiated primary mouse keratinocytes revealed multiple physiologically sensitive chromatin interactions between the 923 enhancer and EDC gene promoters, thus depicting the dynamic chromatin topology of the EDC. We elucidate a mechanistic link between c-Jun/AP-1 and 923, whereby AP-1- and 923-mediated EDC chromatin remodeling are required for functional EDC gene activation. Thus, we identify a critical enhancer/transcription factor axis governing the dynamic regulation of the EDC chromatin architecture and gene expression and provide a framework for future studies toward understanding gene regulation in cutaneous diseases.

ΔNp63 controls a TLR3-mediated mechanism that abundantly provides thymic stromal lymphopoietin in atopic dermatitis

In the skin lesions of atopic dermatitis (AD), keratinocytes release large quantities of thymic stromal lymphopoietin (TSLP), causing unfavorable inflammation along with skin damage. Nevertheless, how TSLP influences keratinocytes themselves is still unknown. In this study, we showed that ΔNp63, a p53-homologue, predominantly expressed in keratinocytes regulated the receptor complex of TSLP, which determines susceptibility to self-derived TSLP. Expression of TSLP receptors in skin tissues and keratinocytes was assessed by immunohistochemistry and quantitative RT-PCR, and in vitro studies were also performed to examine the functional relevance of ΔNp63 in the expression of TSLP receptors and the constituting autocrine and/or paracrine pathway of TSLP under the condition of stimuli to innate receptors sensing cell damage. The results showed that normal keratinocytes in the upper epidermis preferentially expressed TSLP receptors and conversely lacked ΔNp63, which has an inhibitory effect on the expression of TSLP receptors. Interestingly, the epidermis of AD lesions was found to abundantly contain keratinocytes with low or undetectable levels of ΔNp63 (ΔNp63(lo/-)). Moreover, in the absence of ΔNp63, keratinocytes readily presented TSLP and other cytokines by stimuli through Toll-like receptor 3 (TLR3). Together with the evidence that extrinsic TSLP itself augments TSLP production by keratinocytes without ΔNp63, the results indicate that ΔNp63(lo/-) keratinocytes generate TSLP through a putative autocrine and/or paracrine pathway upon TLR3 stimulation within AD lesions, since moieties of damaged cells and pathogens stimulate TLR3.

Dysregulation of the Wnt pathway in adult eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease characterized pathologically by eosinophil infiltration. In addition to loss of barrier integrity, a dominant T Helper 2-associated immune response and strong allergic connection, the esophagus tissue undergoes dramatic changes, with frequent presence of mucosal rings, strictures, linear furrows, and trachealization. Although the inflammatory mechanisms behind this disease are being increasingly well understood, the structural features remain unexplained. We examined the expression of key members of the Wnt-signaling pathway in biopsies from patients with EoE. This pathway has been shown to be critically important in regulating cellular homeostasis, growth, and differentiation and to be dysregulated in several disease conditions. Biopsies from adult EoE patients were collected by endoscopy and mRNA extracted. After cDNA synthesis, the relative gene expression from key upstream (secreted frizzled-related protein 1) and downstream (c-myc and Cyclin D1) molecules in the Wnt pathway, as well as several Wnt pathway members (Wnt1, Axin1, low-density lipoprotein receptor-related protein 6, glycogen synthase kinase 3 beta, and β-catenin), were determined. Biopsies from patients with EoE displayed significantly higher expression of secreted frizzed-related protein 1 than controls, as well as reductions in Cyclin D1 and c-myc. In contrast, there were no differences in the Wnt pathway molecules. The levels of expression of Cyclin D1 and c-myc, as well as β-catenin, in EoE patients showed strong correlations with the frequency of esophageal eosinophils. Our findings suggest that although there are no changes in the overall levels of key Wnt pathway genes in adult EoE, there is evidence for dysregulation of upstream and downstream regulators of Wnt signaling. Importantly, the associations with eosinophilia suggest that these may participate in the pathogenesis of this disease and be markers of disease severity.

Mechanisms of abnormal lamellar body secretion and the dysfunctional skin barrier in patients with atopic dermatitis

I review how diverse inherited and acquired abnormalities in epidermal structural and enzymatic proteins converge to produce defective permeability barrier function and antimicrobial defense in patients with atopic dermatitis (AD). Although best known are mutations in filaggrin (FLG), mutations in other member of the fused S-100 family of proteins (ie, hornerin [hrn] and filaggrin 2 [flg-2]); the cornified envelope precursor (ie, SPRR3); mattrin, which is encoded by TMEM79 and regulates the assembly of lamellar bodies; SPINK5, which encodes the serine protease inhibitor lymphoepithelial Kazal-type trypsin inhibitor type 1; and the fatty acid transporter fatty acid transport protein 4 have all been linked to AD. Yet these abnormalities often only predispose to AD; additional acquired stressors that further compromise barrier function, such as psychological stress, low ambient humidity, or high-pH surfactants, often are required to trigger disease. T(H)2 cytokines can also compromise barrier function by downregulating expression of multiple epidermal structural proteins, lipid synthetic enzymes, and antimicrobial peptides. All of these inherited and acquired abnormalities converge on the lamellar body secretory system, producing abnormalities in lipid composition, secretion, and/or extracellular lamellar membrane organization, as well as antimicrobial defense. Finally, I briefly review therapeutic options that address this new pathogenic paradigm.

Topically applied ZnO nanoparticles suppress allergen induced skin inflammation but induce vigorous IgE production in the atopic dermatitis mouse model

BACKGROUND

Metal oxide nanoparticles such as ZnO are used in sunscreens as they improve their optical properties against the UV-light that causes dermal damage and skin cancer. However, the hazardous properties of the particles used as UV-filters in the sunscreens and applied to the skin have remained uncharacterized.

METHODS

Here we investigated whether different sized ZnO particles would be able to penetrate injured skin and injured allergic skin in the mouse atopic dermatitis model after repeated topical application of ZnO particles. Nano-sized ZnO (nZnO) and bulk-sized ZnO (bZnO) were applied to mechanically damaged mouse skin with or without allergen/superantigen sensitization. Allergen/superantigen sensitization evokes local inflammation and allergy in the skin and is used as a disease model of atopic dermatitis (AD).

RESULTS

Our results demonstrate that only nZnO is able to reach into the deep layers of the allergic skin whereas bZnO stays in the upper layers of both damaged and allergic skin. In addition, both types of particles diminish the local skin inflammation induced in the mouse model of AD; however, nZnO has a higher potential to suppress the local effects. In addition, especially nZnO induces systemic production of IgE antibodies, evidence of allergy promoting adjuvant properties for topically applied nZnO.

CONCLUSIONS

These results provide new hazard characterization data about the metal oxide nanoparticles commonly used in cosmetic products and provide new insights into the dermal exposure and hazard assessment of these materials in injured skin.

2014 update on atopic dermatitis in children

PURPOSE OF REVIEW

The prevalence of pediatric atopic dermatitis (AD) has increased throughout the world, now ranging from 10 to 20% in developed countries. Pediatric patients with AD make up a substantial proportion of patients seen by general pediatricians, allergists, dermatologists, and other specialists. As such, there is a need to optimize understanding and management of AD.

RECENT FINDINGS

The traditional atopic comorbidities of AD have now expanded to include associations with nonatopic conditions such as attention deficit hyperactivity disorder. Furthermore, with insights from basic, translational, and clinical research, experts have a more comprehensive knowledge of the genetic, immunological, and environmental factors influencing the development of AD. With this new perception, innovative approaches to the management of AD have developed with an emphasis on preventive rather than reactive care. The role of biological agents in the treatment of this common, yet chronic, disease of the skin has not been clearly elucidated.

SUMMARY

There have been several recent breakthroughs in the diagnosis, pathophysiology, and management of AD. Despite these advances, much work is still needed in order to ensure optimal care for AD sufferers.

The diagnosis and graded therapy of atopic dermatitis

BACKGROUND

Atopic dermatitis is the most common skin disease in children, with a prevalence of 10% to 15%, and is common in adults as well. Close coordination between primary care physicians and specialists is essential for the adequate treatment of chronically and severely affected patients.

METHOD

This article is a review of pertinent publications that were retrieved by a selective search in Pubmed, with additional consideration of the guidelines of the Association of Medical Scientific Societies in Germany (AWMF) and the European Dermatology Forum.

RESULTS

Trigger factors such as skin irritants, allergens, microbial pathogens, and psychological factors can affect the condition of the skin differently in individual patients and should be individually assessed. The use of skin moisturising creams or emollients along with avoidance of specific and unspecific irritants is of great importance, as these patients have an impaired cutaneous barrier. Topical anti-inflammatory treatment with glucocorticoids or calcineurin inhibitors is a central part of the management of atopic dermatitis; in exceptional cases, severely affected patients are treated with systemic anti-inflammatory drugs. Interdisciplinary patient education has been found to be an effective tool in the complex management of this disease. Chronically and severely affected patients present special challenges for diagnosis and treatment.

CONCLUSION

Recent advances in the understanding of the molecular basis of cutaneous barrier disorders and of congenital and acquired immune disorders have led to new approaches to the treatment of atopic dermatitis.

Knock-down of filaggrin does not affect lipid organization and composition in stratum corneum of reconstructed human skin equivalents

Human skin mainly functions as an effective barrier against unwanted environmental influences. The barrier function strongly relies on the outermost layer of the skin, the stratum corneum (SC), which is composed of corneocytes embedded in an extracellular lipid matrix. The importance of a proper barrier function is shown in various skin disorders such as atopic dermatitis (AD), a complex human skin disorder strongly associated with filaggrin (FLG) null mutations, but their role in barrier function is yet unclear. To study the role of FLG in SC barrier properties in terms of SC lipid organization and lipid composition, we generated an N/TERT-based 3D-skin equivalent (NSE) after knock-down of FLG with shRNA. In these NSEs, we examined epidermal morphogenesis by evaluating the expression of differentiation markers keratin 10, FLG, loricrin and the proliferation marker ki67. Furthermore, the SC was extensively analysed for lipid organization, lipid composition and SC permeability. Our results demonstrate that FLG knock-down (FLG-KD) did not affect epidermal morphogenesis, SC lipid organization, lipid composition and SC permeability for a lipophilic compound in NSEs. Therefore, our findings indicate that FLG-KD alone does not necessarily affect the functionality of a proper barrier function.

Local burn injury impairs epithelial permeability and antimicrobial peptide barrier function in distal unburned skin

OBJECTIVES

Our objective was to characterize the mechanisms by which local burn injury compromises epithelial barrier function in burn margin, containing the elements necessary for healing of the burn site, and in distal unburned skin, which serves as potential donor tissue.

DESIGN

Experimental mouse scald burn injury.

SETTING

University Research Laboratory.

SUBJECTS

C57/Bl6 Male mice, 8-12 weeks old.

INTERVENTIONS

To confirm that dehydration was not contributing to our observed barrier defects, in some experiments mice received 1 mL of saline fluid immediately after burn, while a subgroup received an additional 0.5 mL at 4 hours and 1 mL at 24 hours following burn. We then assessed skin pH and transepidermal water loss every 12 hours on the burn wounds for 72 hours postburn.

MEASUREMENTS AND MAIN RESULTS

Burn margin exhibited increased epidermal barrier permeability indicated by higher pH, greater transepidermal water loss, and reduced lipid synthesis enzyme expression and structural protein production up to 96 hours postburn. By contrast, antimicrobial peptide production and protease activity were elevated in burn margin. Skin extracts from burn margin did not exhibit changes in the ability to inhibit bacterial growth. However, distal unburned skin from burned mice also demonstrated an impaired response to barrier disruption, indicated by elevated transepidermal water loss and reduced lipid synthesis enzyme and structural protein expression up to 96 hours postburn. Furthermore, skin extracts from distal unburned skin exhibited greater protease activity and a reduced capacity to inhibit bacterial growth of several skin pathogens. Finally, we established that antimicrobial peptide levels were also altered in the lung and bladder, which are common sites of secondary infection in burn-injured patients.

CONCLUSIONS

These findings reveal several undefined deficiencies in epithelial barrier function at the burn margin, potential donor skin sites, and organs susceptible to secondary infection. These functional and biochemical data provide novel insights into the mechanisms for graft failure and secondary infection after burn injury.

Hypoxia-inducible factors regulate filaggrin expression and epidermal barrier function

A functional epidermal skin barrier requires the formation of a cornified envelope from terminally differentiating keratinocytes. During this process, multiple genetic and environmental signals coordinately regulate protein expression and tissue differentiation. Here we describe a critical role for hypoxia-inducible factors (HIFs) in the regulation of filaggrin expression and skin barrier formation. Similar to other mammalian tissues, fetal epidermis in mice is normally O₂-deprived. Simultaneous deletion of Hif1a and Hif2a in murine epidermis revealed defects in keratinocyte terminal differentiation and epidermal barrier formation. Mice lacking Hif1a and Hif2a in the epidermis exhibited dry flaky skin, impaired permeability barrier, and enhanced sensitivity to cutaneous allergens. These defects were correlated with stratum granulosum attenuation and reduced filaggrin expression. Hypoxic treatment of primary keratinocytes induced filaggrin (Flg) gene expression in a HIF1α- and HIF2α-dependent manner, suggesting that one mechanism by which Hif1a and Hif2a loss causes epidermal barrier defects in mice lies in Flg dysregulation. Therefore, low O₂ tension is an essential component of the epidermal environment that contributes to skin development and function.

Paradoxical benefits of psychological stress in inflammatory dermatoses models are glucocorticoid mediated

Acute psychological stress (PS) mobilizes metabolic responses that are of immediate benefit to the host, but the current medical paradigm holds that PS exacerbates systemic and cutaneous inflammatory disorders. Although the adverse consequences of PS are usually attributed to neuroimmune mechanisms, PS also stimulates an increase in endogenous glucocorticoids (GCs) that compromises permeability barrier homeostasis, stratum corneum cohesion, wound healing, and epidermal innate immunity in normal skin. Yet, if such PS-induced increases in GC were uniformly harmful, natural selection should have eliminated this component of the stress response. Hence, we hypothesized here instead that stress-induced elevations in endogenous GC could benefit, rather than aggravate, cutaneous function and reduce inflammation in three immunologically diverse mouse models of inflammatory diseases. Indeed, superimposed exogenous (motion-restricted) stress reduced, rather than aggravated inflammation and improved epidermal function in all three models, even normalizing serum IgE levels in the atopic dermatitis model. Elevations in endogenous GC accounted for these apparent benefits, because coadministration of mifepristone prevented stress-induced disease amelioration. Thus, exogenous stress can benefit rather than aggravate cutaneous inflammatory dermatoses through the anti-inflammatory activity of increased endogenous GC.

Filaggrin gene mutations in African Americans with both ichthyosis vulgaris and atopic dermatitis

Atopic dermatitis (AD) and ichthyosis vulgaris (IV) are two common disorders of epidermal homeostasis resulting in dry skin. The profilaggrin gene, located on chromosome 1q22, encodes a keratin filament aggregating protein (filaggrin) that is essential to forming the epidermal barrier and maintaining hydration. Null mutations in filaggrin have been found to underlie IV and are common in patients with AD, but the minority of African Americans with AD or IV show these mutations in filaggrin. We have selectively studied African Americans with both AD and IV to maximize the possibility of finding filaggrin null mutations in this population. DNA was collected using buccal swabs from 18 African American children with both AD and IV and 17 African American controls without either of these diseases. Purified genomic DNA was amplified using polymerase chain reaction from three regions of the filaggrin gene, exon 3, including R501X, 2282del4, E2554X, R2447X, 1249insG, R826X, 2767insT, and E2422X. Of the African American children with both AD and IV, 22.2% were heterozygous for filaggrin null mutations. Out of the control group, one carried a null mutation and was later discovered to have a history of asthma. Null mutations found in this population included R501X (n = 1), 2282del4 (n = 2), and R826X (n = 2, including the control patient). Our data demonstrate a prevalence of filaggrin mutations in the African American population that exceeds previously published data, although the overall prevalence is still lower than in other populations. It is likely that factors other than known FLG mutations are involved in African American patients.

Filaggrin-stratified transcriptomic analysis of pediatric skin identifies mechanistic pathways in patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD; eczema) is characterized by a widespread abnormality in cutaneous barrier function and propensity to inflammation. Filaggrin is a multifunctional protein and plays a key role in skin barrier formation. Loss-of-function mutations in the gene encoding filaggrin (FLG) are a highly significant risk factor for atopic disease, but the molecular mechanisms leading to dermatitis remain unclear.

OBJECTIVE

We sought to interrogate tissue-specific variations in the expressed genome in the skin of children with AD and to investigate underlying pathomechanisms in atopic skin.

METHODS

We applied single-molecule direct RNA sequencing to analyze the whole transcriptome using minimal tissue samples. Uninvolved skin biopsy specimens from 26 pediatric patients with AD were compared with site-matched samples from 10 nonatopic teenage control subjects. Cases and control subjects were screened for FLG genotype to stratify the data set.

RESULTS

Two thousand four hundred thirty differentially expressed genes (false discovery rate, P < .05) were identified, of which 211 were significantly upregulated and 490 downregulated by greater than 2-fold. Gene ontology terms for "extracellular space" and "defense response" were enriched, whereas "lipid metabolic processes" were downregulated. The subset of FLG wild-type cases showed dysregulation of genes involved with lipid metabolism, whereas filaggrin haploinsufficiency affected global gene expression and was characterized by a type 1 interferon-mediated stress response.

CONCLUSION

These analyses demonstrate the importance of extracellular space and lipid metabolism in atopic skin pathology independent of FLG genotype, whereas an aberrant defense response is seen in subjects with FLG mutations. Genotype stratification of the large data set has facilitated functional interpretation and might guide future therapy development.

Associations of filaggrin gene loss-of-function variants and human papillomavirus-related cancer and pre-cancer in Danish adults

Purpose

Filaggrin proteins are expressed in the skin, oral cavity, oesophagus, and cervical mucose. Loss-of-function mutations in the filaggrin gene (FLG) reduce filaggrin expression and cause an impaired skin barrier function. We hypothesized that FLG mutation carriers would be more susceptible to human papillomavirus (HPV) infection and thus a higher risk of HPV-related cancer and pre-cancer. We investigated the association of the FLG genotype with incidence of HPV-related cancer of cervix, vagina, vulva, penis, anus and head and neck, and pre-cancer of the cervix.

Methods

We included 13,376 persons from four population-based studies conducted in the same background population in Copenhagen, Denmark. Participants were genotyped for the most common FLG mutations in Europeans. Information on cancer was obtained from The Danish Cancer Registry until 11 July 2011.

Results

There were 489 cases of prevalent and 97 cases of incident HPV-related cancer and pre-cancer (median follow-up 11.5 years). There was a statistically significant association between FLG genotype and incident HPV-related cancer and pre-cancer with a hazard ratio, HR = 2.1 (95% confidence intervals, CI: 1.2, 3.7) for FLG mutation carriers vs. wild types.

Conclusions

FLG loss-of-function mutations were associated with higher incidence of HPV-related cancers and pre-cancers that are potentially screening and vaccine preventable.

Epicutaneously applied Der p 2 induces a strong TH 2-biased antibody response in C57BL/6 mice, independent of functional TLR4

Background

The major house dust mite allergen Der p 2 is a structural and functional homologue of MD-2 within the TLR4–CD14–MD-2 complex. An asthma mouse model in TLR4-deficient mice recently suggested that the allergic immune response against Der p 2 is solely dependent on TLR4 signaling. We investigated whether similar mechanisms are important for Der p 2 sensitization via the skin.

Methods

In an epicutaneous sensitization model, the response to recombinant Der p 2 in combination with or without lipopolysaccharide (LPS) was compared between C57BL/6 WT and TLR4-deficient mice. We further analyzed possible adjuvant function of exogenous cysteine proteases.

Results

Sensitization with rDer p 2 induced similar levels of allergen-specific IgG1 and IgE antibodies in both mouse strains. LPS increased the systemic (antibody levels, cytokine release by restimulated splenocytes) and local (infiltration of immune cells into the skin) Th2 immune responses, which against our expectations were stronger in the absence of functional TLR4 expression. Barrier disruption by papain, a protease with structural homology to Der p 1, did not enhance the sensitization capacity of rDer p 2. However, the presence of LPS increased the stability of rDer p 2 against the protease.

Conclusion

Our data suggest that rDer p 2 alone can cause a strong T_H2-biased response via the skin being enhanced in the presence of LPS. This response is not reliant on functional TLR4, but vice versa TLR4 expression rather protects against epicutaneous sensitization to house dust mite allergen Der p 2.

Filaggrin gene mutation c.3321delA is associated with various clinical features of atopic dermatitis in the Chinese Han population

Background

We confirmed that the filaggrin gene mutation c.3321delA is associated with atopic dermatitis in our previous genome wide association study of the Chinese Han population. c.3321delA is the most common filaggrin gene mutation in Chinese atopic dermatitis patients but is not present in European populations.

Objective

To investigate the genetic model for the c.3321delA mutation and to determine the correlation between c.3321delA and atopic dermatitis clinical phenotypes in the Chinese Han population.

Method

The filaggrin gene mutation c.3321delA was sequenced in 1,080 atopic dermatitis patients and 908 controls from the Chinese population. The χ² test, ANOVA,nonparametric tests and logistic regression were used to investigate the relationship between the c.3321delA genotype and atopic dermatitis clinical phenotypes in the Chinese Han population.

Results

Analyses of the genetic model revealed that the additive model best described the c.3321delA mutation (P = 3.09E-11, OR = 3.43, 95%CI = 2.38–4.96). Stratified analyses showed that the c.3321delA allele frequency distribution is significantly associated with concomitant skin xerosis (P = 1.68E-03, OR = 2.13,95%CI = 1.32–3.46), palmar hyperlinearity (P = 3.64E-17, OR = 4.0,95%CI = 2.86–5.70), white dermatographism (P = 4.25E-03, OR = 1.82,95%CI = 1.22–2.71), food intolerance (P = 1.51E-03, OR = 1.76,95%CI = 1.23–2.50) and disease severity ( P = 9.67E-05).

Conclusion

Our study indicates that the filaggrin gene mutation c.3321delA is associated with clinical phenotypes of atopic dermatitis in the Chinese Han population, which might help us gain a better understanding on the pathogenesis of atopic dermatitis.

[Personalised medicine for the diagnosis and treatment of allergic diseases]

Immunoglobulin E (IgE) mediated allergic diseases are characterised by heterogeneous clinical phenotypes and a large variety of different sensitisation patterns. Apart from genetic predisposition several environmental factors play a role in sensitisation and elicitation of symptoms. Since the majority of clinically relevant allergens are now available as purified recombinant allergens component-resolved in vitro diagnosis allows the sensitization profile of allergic patients to be determined at the molecular level. Such data may allow physicians to draw conclusions on the severity and persistence of a given allergic disease and to predict the outcome of allergen-specific immunotherapy (SIT) However, the potential of this approach needs to be demonstrated in controlled clinical trials. Moreover, in the context of atopic dermatitis, allergic rhinitis, allergic bronchial asthma as well as the atopic march several screening-biomarkers, diagnostic and prognostic biomarkers, biomarkers of severity and predictive biomarkers are presented and discussed in this article. Traditionally a relevant proportion of allergen-specific immunotherapies is performed in a personalised manner using named patient products manufactured on the basis of an individual prescription. Such named patient products are often mixtures containing several allergen extracts from different sources. However, there is no proven evidence for the safety and efficacy of this approach. In Germany the Therapy Allergen Ordinance ("Therapieallergene-Verordnung", TAV) regulates that in the future allergen products for SIT of insect venom allergies, allergies to pollen of early flowering trees and grass pollen and house dust mite allergies cannot be marketed as named patient products, but always require a marketing authorisation. Thus personalised SIT with named patient products is restricted to the treatment of less prevalent allergies, for which the generation of state-of-the-art clinical data is more difficult. Several recombinant allergens are currently evaluated in phase III clinical trials. In contrast to allergen extracts recombinant allergens offer the possibility to treat patients with a precisely adjusted mixture of the disease-eliciting allergen molecules. However, the implementation of this personalised approach to SIT within the given regulatory framework represents a challenge to regulators.

Skin barrier defects in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin condition with complex etiology that is dependent upon interactions between the host and the environment. Acute skin lesions exhibit the features of a Th2-driven inflammatory disorder, and many patients are highly atopic. The skin barrier plays key roles in immune surveillance and homeostasis, and in preventing penetration of microbial products and allergens. Defects that compromise the structural integrity or else the immune function of the skin barrier play a pivotal role in the pathogenesis of AD. This article provides an overview of the array of molecular building blocks that are essential to maintaining healthy skin. The basis for structural defects in the skin is discussed in relation to AD, with an emphasis on filaggrin and its genetic underpinnings. Aspects of innate immunity, including the role of antimicrobial peptides and proteases, are also discussed.

Evidence That Loss-of-Function Filaggrin Gene Mutations Evolved in Northern Europeans to Favor Intracutaneous Vitamin D3 Production

Skin pigmentation lightened progressively to a variable extent, as modern humans emigrated out of Africa, but extreme lightening occurred only in northern Europeans. Yet, loss of pigmentation alone cannot suffice to sustain cutaneous vitamin D3 (VD3) formation at the high latitudes of northern Europe. We hypothesized that loss-of-function mutations in the epidermal structural protein, filaggrin (FLG), could have evolved to sustain adequate VD3 status. Loss of FLG results in reduced generation of trans-urocanic acid, the principal endogenous ultraviolet-B (UV-B) filter in lightly-pigmented individuals. Accordingly, we identified a higher prevalence of FLG mutations in northern European populations when compared to more southern European, Asian and African populations that correlates significantly with differences in circulating 25-OH-VD3 levels in these same populations. By allowing additional UV-B penetration and intracutaneous VD3 formation, the latitude-dependent gradient in FLG mutations, likely together with other concurrent mutations in VD3 metabolic pathways, provide a non-pigment-based mechanism that sustains higher levels of circulating VD3 in northern Europeans. At the time that FLG mutations evolved, xerosis due to FLG deficiency was a lesser price to pay for enhanced VD3 production. Yet, the increase in FLG mutations has inadvertently contributed to an epidemic of atopic diseases that has emerged in recent decades.

Thymic stromal lymphopoietin variation, filaggrin loss of function, and the persistence of atopic dermatitis

IMPORTANCE

Atopic dermatitis (AD) is a common chronic illness of childhood.

OBJECTIVE

To evaluate the association between thymic stromal lymphopoietin (TSLP) variation and the persistence of skin symptoms of AD.

DESIGN, SETTING, AND PARTICIPANTS

A prospective cohort study was conducted in the general community. Participants included 796 children enrolled in the Pediatric Eczema Elective Registry. EXPOSURE Evaluation of TSLP variation.

MAIN OUTCOMES AND MEASURES

Self-reported outcome of whether a child's skin had no symptoms of AD and required no medications for 6 months at 6-month intervals.

RESULTS

We evaluated 14 variants of TSLP. The variant rs1898671 was significantly associated with the outcome in white children (P = .01). As measured by overlapping CIs, similar odds ratios (ORs) were noted among whites (OR, 1.72; 95% CI, 1.11-2.66) and African Americans (1.33; 0.52-3.45). Further within the subcohort of individuals with a filaggrin protein (FLG) loss-of-function mutation, those with TSLP variation were more likely to have less-persistent disease (OR, 4.92; 95% CI, 2.04-11.86).

CONCLUSIONS AND RELEVANCE

The TSLP variation is associated with less persistent AD. Therefore, TSLP may be a potential therapeutic target for the treatment of AD, especially in individuals with diminished barrier function due to FLG mutations. This is an attractive hypothesis that can be tested in clinical trials.

Atopic dermatitis phenotypes in childhood

Background

Atopic dermatitis (AD) is a chronic inflammatory skin disease and can be the first step of the atopic march.

Objective

In this retrospective study, we analysed the immunological and clinical patterns of AD in a group of children affected by the disease since their first years of life, in order to evaluate if and how these patterns can change over time, and to identify biomarkers that can possibly correlate with the clinical phenotype.

Methods

We enrolled Caucasian children with diagnosis of AD performed by a specialist on the basis of Hanifin and Rajka’s criteria and with a first clinical and laboratory evaluation before 5 years of age. Patients were divided in 2 groups: IgE-associated AD (with or without allergic respiratory diseases) and non-IgE-associated AD.

Results

Among 184 patients enrolled in this study, at the beginning 30/184 were classified as having non-IgE-associated AD, but during follow-up, at the median age of 36 months, 15 patients became allergic. All 15 patients who switched from the non-IgE to the IgE-associated form had a significantly earlier onset of AD than those who did not switch. Dust mite sensitization seem to be the best biomarker (OR 2.86) to predict the appearance of allergic respiratory diseases.

Conclusion

IgE-associated AD is more frequent in childhood than non-IgE-associated AD. These two phenotypes are different in the age of onset and in the remission patterns. In the first years of life, it is important to distinguish the different phenotypes in order to evaluate possible allergic related conditions.

Sensitization to food and inhalant allergens in relation to age and wheeze among children with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is common in children; however, persistence of AD with or without asthma is less common. Longitudinal studies remain limited in their ability to characterize how IgE antibody responses evolve in AD, and their relationship with asthma.

OBJECTIVE

To use a cross-sectional study design of children with active AD to analyse age-related differences in IgE antibodies and relation to wheeze.

METHODS

IgE antibodies to food and inhalant allergens were measured in children with active AD (5 months to 15 years of age, n = 66), with and without history of wheeze.

RESULTS

Whereas IgE antibodies to foods persisted at a similar prevalence and titre throughout childhood, IgE antibodies to all aeroallergens rose sharply into adolescence. From birth, the chance of sensitization for any aeroallergen increased for each 12-month increment in age (OR ≥ 1.21, P < 0.01), with the largest effect observed for dust mite (OR = 1.56, P < 0.001). A steeper age-related rise in IgE antibody titre to dust mite, but no other allergen was associated with more severe disease. Despite this, sensitization to cat was more strongly associated with wheeze (OR = 4.5, P < 0.01), and linked to Fel d 1 and Fel d 4, but not Fel d 2. Comparison of cat allergic children with AD to those without, revealed higher IgE levels to Fel d 2 and Fel d 4 (P < 0.05), but not Fel d 1.

CONCLUSIONS AND CLINICAL RELEVANCE

Differences in sensitization to cat and dust mite among young children with AD may aid in identifying those at increased risk for disease progression and development of asthma. Early sensitization to cat and risk for wheeze among children with AD may be linked to an increased risk for sensitization to a broader spectrum of allergen components from early life. Collectively, our findings argue for early intervention strategies designed to mitigate skin inflammation in children with AD.

Dual role of interleukin-23 in epicutaneously-sensitized asthma in mice

BACKGROUND

Interleukin (IL)-23/Th17 axis plays an important role in the pathophysiology of asthma and eczema, however, there are some conflicting data about the effects of this system on allergic airway inflammation. In the present study, we aim to dissect the spatiotemporal differences in the roles of IL-23 in an epicutaneously-sensitized asthma model of mice.

METHODS

C57BL/6 mice were sensitized to ovalbumin (OVA) by patch application on the skin, followed by airway exposure to aerosolized OVA. During sensitization and/or challenge phase, either a specific neutralizing antibody (Ab) against IL-23 or control IgG was injected intraperitoneally. On days 1 and 8 after the final OVA exposure, airway inflammation and responsiveness to methacholine, immunoglobulin levels in serum, and cytokine release from splenocytes were evaluated. Skin Il23a mRNA levels were evaluated with quantitative RT-PCR.

RESULTS

Patch application time-dependently increased the expression of Il23a mRNA expression in the skin. Treatment with the anti-IL-23 Ab during sensitization phase alone significantly reduced the number of eosinophils in bronchoalveolar lavage fluids and peribronchial spaces after allergen challenge compared with treatment with control IgG. Anti-IL-23 Ab also reduced serum levels of OVA-specific IgG1. In contrast, treatment with the anti-IL-23 Ab during the challenge phase alone rather exacerbated airway hyperresponsiveness to methacholine with little effects on airway eosinophilia or serum IgG1 levels.

CONCLUSIONS

IL-23 expressed in the skin during the sensitization phase plays an essential role in the development of allergic phenotypes, whereas IL-23 in the airways during the challenge phase suppresses airway hyperresponsiveness.

Atopic dermatitis in children

A 7-year-old girl presented with atopic dermatitis (AD) that did not respond to standard therapy. She was avoiding dairy, egg, and wheat in her diet because of a history of skin flares. Her weight gain was poor, and laboratory test results showed low iron and zinc levels. Over the previous 6 months, she had been prescribed numerous courses of antibiotics, but, despite this, she continued to have secondary skin infections as well as deep circumscribed erosions on her shins. She was awake much of the night because of scratching and displayed repetitive and habitual behavior. She also had troublesome allergic rhinoconjunctivitis with positive allergy testing results to house dust mite. Methicillin-resistant Staphylococcus aureus was isolated from her skin, which was successfully treated with appropriate antibiotics and flares controlled with topical antiseptics and better personal and caregiver hygiene. Although milk, egg, and wheat specific IgE were raised, these foods were successfully reintroduced back into her diet with improvement of her nutritional status and no flare of her AD. In view of her habitual behavior and family history of obsessive compulsive disorder, she underwent cognitive behavioral therapy, and her general well-being, sleep, and ulcers over her shins improved. Despite high house dust mite-specific IgE, house dust mite sublingual immunotherapy led to no additional improvement in her AD although it did improve her rhinitis. Although there may be no "quick fixes" in patients with AD, the clinician should be aware of antimicrobial, allergen, and educational and/or behavioral interventions, which may greatly improve eczema severity and the patient's well-being.

Atopic dermatitis-associated protein interaction network lead to new insights in chronic sulfur mustard skin lesion mechanisms

Chronic sulfur mustard skin lesions (CSMSLs) are the most common complications of sulfur mustard exposure; however, its mechanism is not completely understood.According to clinical signs, there are similarities between CSMSL and atopic dermatitis (AD). In this study, proteomic results of AD were reviewed and the AD-associated protein-protein interaction network (PIN) was analyzed. According to centrality measurements, 16 proteins were designated as pivotal elements in AD mechanisms. Interestingly, most of these proteins had been reported in some sulfur mustard-related studies in late and acute phases separately. Based on the gene enrichment analysis, aging, cell response to stress, cancer, Toll- and NOD-like receptor and apoptosis signaling pathways have the greatest impact on the disease. By the analysis of directed protein interaction networks, it is concluded that TNF, IL-6, AKT1, NOS3 and CDKN1A are the most important proteins. It is possible that these proteins play role in the shared complications of AD and CSMSL including xerosis and itching.

Atopic dermatitis: natural history, diagnosis, and treatment

Atopic dermatitis is an inflammatory skin disease with early onset and with a lifetime prevalence of approximately 20%. The aetiology of atopic dermatitis is unknown, but the recent discovery of filaggrin mutations holds promise that the progression of atopic dermatitis to asthma in later childhood may be halted. Atopic dermatitis is not always easily manageable and every physician should be familiar with the fundamental aspects of treatment. This paper gives an overview of the natural history, clinical features, and treatment of atopic dermatitis.

Associations of filaggrin gene loss-of-function variants with urinary phthalate metabolites and testicular function in young Danish Men

BACKGROUND

Filaggrin is an epidermal protein that is crucial for skin barrier function. Up to 10% of Europeans and 5% of Asians carry at least one null allele in the filaggrin gene (FLG). Reduced expression of filaggrin in carriers of the null allele is associated with facilitated transfer of allergens across the epidermis. We hypothesized that these individuals may have increased transdermal uptake of endocrine disruptors, including phthalates.

OBJECTIVES

We investigated urinary excretion of phthalate metabolites and testicular function in young men with and without FLG loss-of-function variants in a cross-sectional study of 861 young men from the general Danish population.

METHODS

All men were genotyped for FLG R501X, 2282del4, and R2447X loss-of-function variants. We measured urinary concentrations of 14 phthalate metabolites and serum levels of reproductive hormones. We also evaluated semen quality.

RESULTS

Sixty-five men (7.5%) carried at least one FLG-null allele. FLG-null carriers had significantly higher urinary concentrations of several phthalate metabolites, including a 33% higher concentration of MnBP (mono-n-butyl phthalate; 95% CI: 16, 51%). FLG-null variants were not significantly associated with reproductive hormones or semen quality parameters.

CONCLUSION

This study provides evidence that carriers of FLG loss-of-function alleles may have higher internal exposure to phthalates, possibly due to increased transepidermal absorption. FLG loss-of-function variants may indicate susceptible populations for which special attention to transepidermal absorption of chemicals and medication may be warranted.

The role of filaggrin in the skin barrier and disease development

Filaggrin is a structural protein that is fundamental in the development and maintenance of the skin barrier. The function of filaggrin and its involvement in various cutaneous and extracutaneous disorders has been the subject of considerable research in recent years. Mutations in FLG, the gene that encodes filaggrin, have been shown to cause ichthyosis vulgaris, increase the risk of atopic dermatitis and other atopic diseases, and exacerbate certain conditions. The present article reviews the current knowledge on the role of filaggrin in the skin barrier, FLG mutations, and the consequences of filaggrin deficiency.

Loss-of-function mutations in the gene encoding filaggrin underlie a Japanese family with food-dependent exercise-induced anaphylaxis

BACKGROUND

Food-dependent exercise-induced anaphylaxis (FDEIA) is a serious food allergy in which anaphylaxis develops when exercise is performed within several hours after food intake. The precise mechanism underlying allergic sensitization in FDEIA has been an important issue but remains poorly understood.

OBJECTIVES

We aimed to elucidate the pathomechanism including the route of allergen sensitization involved in FDEIA.

METHODS

A Japanese family with wheat-dependent exercise-induced anaphylaxis (WDEIA), a specific form of FDEIA, were clinically examined. Mutation analysis of the gene encoding filaggrin (FLG) was also performed.

RESULTS

Two of the family members were confirmed as WDEIA on the basis of their medical history and positive provocation test results. Notably, the two affected individuals in the family had concomitant ichthyosis vulgaris. Mutation analysis of FLG revealed that they carry one or more loss-of-function mutations that have not been described in the Japanese population.

CONCLUSION

These results indicate that FLG mutations might be involved in the pathogenesis of WDEIA in the present case.

Epidermal Differentiation in Barrier Maintenance and Wound Healing

Significance: The epidermal barrier prevents water loss and serves as the body's first line of defense against toxins, chemicals, and infectious microbes. Disruption of the barrier, either through congenital disorders of barrier formation or through wounds, puts the individual at risk for dehydration, hypersensitivity, infection, and prolonged inflammation. Epidermal barrier disorders affect millions of patients in the United States, causing loss of productivity and diminished quality of life for patients and their families, and represent a burden to the health-care system and society. Recent Advances: The genetic basis of many congenital barrier disorders has been identified in recent years, and great advances have been made in the molecular mechanisms of the formation and homeostasis of epidermal barrier, as well as acute and chronic wound healing. Progress in stem cell (SC) biology, particularly in induced pluripotent stem cells (iPSCs) and allogeneic mesenchymal stem cells (MSCs), has opened new doors for cell-based therapy of chronic wounds. Critical Issues: Understanding of the molecular mechanisms of barrier homeostasis in health and disease, as well as contributions of iPSCs and allogeneic MSCs to wound healing, will lead to the identification of novel targets for developing therapeutics for congenital barrier and wound healing disorders. Future Directions: Future studies should focus on better understanding of molecular mechanisms leading to disrupted homeostasis of epidermal barrier to identify potential therapeutic targets to combat its associated diseases.

Survival of an infant with homozygous surfactant protein C (SFTPC) mutation

Lung diseases caused by surfactant protein C (SFTPC) mutations are inherited as autosomal traits with variable penetrance and severity or as sporadic disease caused by a de novo mutation on one allele. Here, we report the case of a child surviving with a homozygous surfactant protein C mutation after aggressive clinical management unlike his six siblings who died in infancy. This presentation raises the suspicion of an autosomal recessive inheritance that is discussed in this report.

Emergence of multiresistant methicillin-resistant Staphylococcus aureus in two patients with atopic dermatitis requiring linezolid treatment

We report two patients with atopic dermatitis who developed methicillin-resistant Staphylococcus aureus (MRSA) skin infections resistant to clindamycin and trimethoprim-sulfamethoxazole requiring repeated linezolid treatment. For one patient and family members who received an aggressive regimen of staphylococcal decolonization, including intranasal mupirocin, dilute bleach baths, and bleach cleansing of household items and surfaces, subsequent culture results demonstrated methicillin-susceptible S. aureus colonization and infection. These findings underscore the challenges presented by multiresistant MRSA infections in children with atopic dermatitis.

Filaggrin-2 variation is associated with more persistent atopic dermatitis in African American subjects

BACKGROUND

Atopic dermatitis (AD) is a common skin disease characterized by recurrent episodes of itching. Genetic variation associated with the persistence of AD has not been described for African American subjects.

OBJECTIVE

We sought to evaluate genetic variation of filaggrin-2 (FLG2) in African American subjects with AD.

METHODS

We evaluated a multiyear prospective cohort study of African American children with AD with respect to FLG2 variation based on whole-exome sequencing, followed by a targeted analysis. We ultimately evaluated the association of rs12568784 and rs16833974 with respect to the persistence of AD symptoms over time.

RESULTS

Whole-exome analysis was conducted on 60 subjects, revealing a premature stop codon in exon 3 at S2377X (rs12568784) and X2392S (rs150529054) and a large exon 3 deletion mutation, Q2053del224. On the basis of a priori criteria, we then studied rs12568784, rs16833974 (H1249R), and Q2053del224. We noted that patients with S2377X (odds ratio [OR], 0.44; 95% CI, 0.25-0.46) and H1249R (OR, 0.23; 05% CI, 0.12-0.46) were significantly less likely to be free of symptoms of AD, and Q2053del224 (OR, 0.54; 95% CI, 0.16-1.80) trended toward this outcome. S2377X and H1249R were in high linkage disequilibrium (D' = 0.95).

CONCLUSIONS

In an African American cohort with AD, FLG2 mutations were associated with more persistent AD. This is the first finding of genetic variation of a skin barrier protein in subjects of African ancestry with AD.

Staphylococcal and streptococcal superantigen exotoxins

SUMMARY This review begins with a discussion of the large family of Staphylococcus aureus and beta-hemolytic streptococcal pyrogenic toxin T lymphocyte superantigens from structural and immunobiological perspectives. With this as background, the review then discusses the major known and possible human disease associations with superantigens, including associations with toxic shock syndromes, atopic dermatitis, pneumonia, infective endocarditis, and autoimmune sequelae to streptococcal illnesses. Finally, the review addresses current and possible novel strategies to prevent superantigen production and passive and active immunization strategies.

Multiscale mathematical modeling and simulation of cellular dynamical process

Epidermal homeostasis is maintained by dynamic interactions among molecules and cells at different spatiotemporal scales. Mathematical modeling and simulation is expected to provide clear understanding and precise description of multiscaleness in tissue homeostasis under systems perspective. We introduce a stochastic process-based description of multiscale dynamics. Agent-based modeling as a framework of multiscale modeling to achieve consistent integration of definitive subsystems is proposed. A newly developed algorithm that particularly aims to perform stochastic simulations of cellular dynamical process is introduced. Finally we review applications of multiscale modeling and quantitative study to important aspects of epidermal and epithelial homeostasis.

New insights into the epidemiology of childhood atopic dermatitis

There is a growing desire to explain the worldwide rise in the prevalence of atopic dermatitis (AD). Trend data on the burden of AD suggest that the picture in the developing world may soon resemble that of wealthier nations, where AD affects over 20% of children. This, combined with significant variations in prevalence within countries, emphasizes the importance of environmental factors. Many hypotheses have been explored, from the modulation of immune priming by hygiene, gut microbiota diversity, and exposure to endotoxins through farm animals to the effects of pollution, climate, and diet. The discovery of the filaggrin skin barrier gene and its importance in AD development and severity has brought the focus on gene-environment interactions and the identification of environmental factors that impact on skin barrier function. This article reviews our current understanding of the epidemiology of AD, with an emphasis on the findings reported in the international literature over the last 5 years.

Protein biomarkers in vernix with potential to predict the development of atopic eczema in early childhood

Background

Atopic eczema (AE) is a chronic inflammatory skin disease, which has increased in prevalence. Evidence points toward lifestyle as a major risk factor. AE is often the first symptom early in life later followed by food allergy, asthma, and allergic rhinitis. Thus, there is a great need to find early, preferentially noninvasive, biomarkers to identify individuals that are predisposed to AE with the goal to prevent disease development.

Objective

To investigate whether the protein abundances in vernix can predict later development of AE.

Methods

Vernix collected at birth from 34 newborns within the Assessment of Lifestyle and Allergic Disease During INfancy (ALADDIN) birth cohort was included in the study. At 2 years of age, 18 children had developed AE. Vernix proteins were identified and quantified with liquid chromatography coupled to tandem mass spectrometry.

Results

We identified and quantified 203 proteins in all vernix samples. An orthogonal projections to latent structures-discriminant analysis (OPLS-DA) model was found with R² = 0.85, Q² = 0.39, and discrimination power between the AE and healthy group of 73.5%. Polyubiquitin-C and calmodulin-like protein 5 showed strong negative correlation to the AE group, with a correlation coefficient of 0.73 and 0.68, respectively, and a P-value of 8.2 E-7 and 1.8 E-5, respectively. For these two proteins, the OPLS-DA model showed a prediction accuracy of 91.2%.

Conclusion

The protein abundances in vernix, and particularly that of polyubiquitin-C and calmodulin-like protein 5, are promising candidates as biomarkers for the identification of newborns predisposed to develop AE.

New insights in the pathogenesis of atopic dermatitis

Atopic dermatitis (AD) is characterized by skin barrier defects and increased interleukin (IL)-4/IL-13 expression. Recent evidence also suggests the involvement of innate immunity including Toll-like receptors, IL-33, IL-25, and innate lymphoid cells in the pathogenesis of AD. This article reviews these innate immune components and how they may become an integral part of prognostic factors and therapeutic targets in the treatment of AD.