Atopy patch test reactions to Malassezia allergens differentiate subgroups of atopic dermatitis patients

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Treatment of atopic dermatitis using topical antifungal drugs: A meta-analysis

Several studies have focused on treating atopic dermatitis (AD) using topical antifungal drugs. However, their findings are inconsistent. This meta-analysis of randomized controlled trials (RCTs) aimed to evaluate the safety and efficacy of topical antifungal drugs for the treatment of AD. We searched prominent databases such as EMBASE, PubMed, Cochrane Library, China Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wanfang Database to retrieve all RCTs on the use of topical antifungal drugs for the treatment of AD. The two authors independently performed screening, extraction, and quality evaluation of data based on inclusion and exclusion criteria. In addition, quantitative synthesis and qualitative description of the results were performed using Review Manager 5.3. Nine studies with a total of 785 subjects were included in the meta-analysis. Based on intervention measures, data were divided into three groups: topical antifungal drugs versus placebo, topical antifungal drugs versus topical glucocorticoids, and topical antifungal drugs plus topical glucocorticoids versus topical glucocorticoids. Risk-of-bias assessments revealed that the random distribution methods and allocation concealment were not ideal; further, some studies had incomplete data and reported selective results. Quantitative analysis revealed that in terms of effective rate, topical antifungal drugs are superior to topical glucocorticoids (p = 0.003), and topical antifungal drugs plus topical glucocorticoids are superior to topical glucocorticoids (p = 0.001). However, no significant differences in adverse reactions were observed between the three groups (p > 0.05). The safety and efficacy of topical antifungal drugs for treating AD cannot be accurately evaluated with existing data. Therefore, additional high-quality and large-sample prospective RCTs are required for further validation to determine the appropriateness of topical antifungal drug use for the treatment of AD in clinical settings.

The Role of the Cutaneous Mycobiome in Atopic Dermatitis

Atopic dermatitis is a chronic inflammatory skin disorder characterized by eczematous lesions, itch, and a significant deterioration in the quality of life. Recently, microbiome dysbiosis has been implicated in the pathogenesis of atopic dermatitis. Changes in the fungal microbiome (also termed mycobiome) appear to be an important factor influencing the clinical picture of this entity. This review summarizes the available insights into the role of the cutaneous mycobiome in atopic dermatitis and the new research possibilities in this field. The prevalence and characteristics of key fungal species, the most important pathogenesis pathways, as well as classic and emerging therapies of fungal dysbiosis and infections complicating atopic dermatitis, are presented.

Single Nucleotide Polymorphism of Dectin-1 Gene Associates with Atopic Dermatitis in Children

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease with complex and multifactorial pathophysiology, involving elements of barrier dysfunction, alterations in cell-mediated immune responses, IgE sensitization, and environmental factors. This encourages the search for predictors of disease development among both genetic markers and environment. AIM: The aim of the study was to examine if genetic factors of Malassezia recognition, or Malassezia colonization may be related to IgE sensitization or to severity of AD. METHODS: The study included 106 patients with eczema and 103 healthy children. Specific IgE against Malassezia mix (m227) was analyzed in 51 patients using immunochemiluminescent method on the ImmunoCAP 100 (Thermo Fisher Scientific Inc., Phadia, Sweden). Genotyping for rs7309123 in Dectin-1 was performed using Real-time PCR. The level of colonization by Malassezia in the scale samples was determined by a real-time PCR assay. RESULTS: Increased IgE to Malassezia spp. was observed in 29,4% of children with eczema. Higher Malassezia spp. – specific IgE titer positively correlated with severity of AD, age of onset, head–neck type of AD, and a higher total IgE. GG genotype rs7309123 Dectin-1 is significantly more often found in the patients than in the control group, but no correlation with IgE sensitization to Malassezia was found. Malassezia restricta and M. globosa were predominant in patients and controls, with some predominance of M. globosa over M. restricta among patients. CONCLUSION: Sensitization to Malassezia, genetic markers in Dectin-1, and Malassezia colonization of the skin can be tools for studying the gene-environment interactions in the pathogenesis of AD.

Characterization of Distinct Microbiota Associated with Scalp Dermatitis in Patients with Atopic Dermatitis

Recent studies have focused on the role of skin microbiota in the pathogenesis of atopic dermatitis (AD). Among the various clinical phenotypes of AD, scalp dermatitis is a commonly observed clinical feature of AD. However, little is known about the pathogenesis of scalp dermatitis in AD. Hence, the aim of this study was to identify the distinct microbiota associated with scalp dermatitis in patients with AD. Using scalp swab samples from 10 patients with AD and 10 healthy controls, this study characterized the scalp microbiota in patients with AD via V3–V4 regions of the 16S rRNA gene sequencing for bacterial identification, and ITS2 gene sequencing for fungal identification. Among bacterial genera, Staphylococcus was the most abundant in AD than in healthy controls, whereas Cutibacterium was the most abundant species in the healthy controls. The most predominant scalp fungal microbiota was Malassezia both in AD and healthy controls, while a higher diversity of non-Malassezia fungi was observed in AD than in healthy controls. The study findings indicate the dysbiosis of scalp microbiota in AD and highlight the potential biomarker role of specific microbiota in AD on the scalp dermatitis.

Malassezia species dysbiosis in natural and allergen-induced atopic dermatitis in dogs

Malassezia dermatitis and otitis are recurrent features of canine atopic dermatitis, increasing the cost of care, and contributing to a reduced quality of life for the pet. The exact pathogenesis of secondary yeast infections in allergic dogs remains unclear, but some have proposed an overgrowth of M. pachydermatis to be one of the flare factors. The distribution of Malassezia populations on healthy and allergic canine skin has not been previously investigated using culture-independent methods. Skin swabs were collected from healthy, naturally affected allergic, and experimentally sensitized atopic dogs. From the extracted DNA, fungal next-generations sequencing (NGS) targeting the ITS region with phylogenetic analysis of sequences for species level classification, and Malassezia species-specific quantitative real-time polymerase chain reaction (qPCR) were performed. M. globosa was significantly more abundant on healthy canine skin by both methods (NGS P < .0001, qPCR P < .0001). M. restricta was significantly more abundant on healthy skin by NGS (P = .0023), and M. pachydermatis was significantly more abundant on naturally-affected allergic skin by NGS (P < .0001) and on allergen-induced atopic skin lesions by qPCR (P = .0015). Shifts in Malassezia populations were not observed in correlation with the development of allergen-induced skin lesions. Differences in the lipid dependency of predominant Malassezia commensals between groups suggests a role of the skin lipid content in driving community composition and raises questions of whether targeting skin lipids with therapeutics could promote healthy Malassezia populations on canine skin.

Skin Commensal Fungus Malassezia and Its Lipases

Malassezia is the most abundant genus in the fungal microflora found on human skin, and it is associated with various skin diseases. Among the 18 different species of Malassezia that have been identified to date, M. restricta and M. globosa are the most predominant fungal species found on human skin. Several studies have suggested a possible link between Malassezia and skin disorders. However, our knowledge on the physiology and pathogenesis of Malassezia in human body is still limited. Malassezia is unable to synthesize fatty acids; hence, it uptakes external fatty acids as a nutrient source for survival, a characteristic compensated by the secretion of lipases and degradation of sebum to produce and uptake external fatty acids. Although it has been reported that the activity of secreted lipases may contribute to pathogenesis of Malassezia, majority of the data were indirect evidences; therefore, enzymes' role in the pathogenesis of Malassezia infections is still largely unknown. This review focuses on the recent advances on Malassezia in the context of an emerging interest for lipases and summarizes the existing knowledge on Malassezia, diseases associated with the fungus, and the role of the reported lipases in its physiology and pathogenesis.

Atopic Dermatitis and Sensitisation to Molecular Components of Alternaria, Cladosporium, Penicillium, Aspergillus, and Malassezia-Results of Allergy Explorer ALEX 2

Progress in laboratory diagnostics of IgE-mediated allergies is being made through the use of component-resolved diagnosis. The aim of our study is to analyze the sensitization profile to allergen reagents in patients suffering from atopic dermatitis with the use of the ALEX 2–Allergy Explorer and especially to show the sensitization to molecular components of molds and yeast. The complete dermatological and allergological examination including the examination of the sensitization to allergen reagents with Allergy Explorer ALEX 2 testing was performed. The relation between the sensitization to molecular components of molds and yeast and the severity of atopic dermatitis, and the occurrence of bronchial asthma and allergic rhinitis was evaluated. Altogether, 100 atopic dermatitis patients were examined—48 men and 52 women, with an average age of 40.9 years. The sensitization to Mala s 6, Mala s 11, Sac c, Asp f 6, Cla h and Cla h 8 correlates to the severity of atopic dermatitis. The sensitization to Sac c, Alt a 6, Cla h, Cla h 8 was observed significantly more frequently in patients suffering from bronchial asthma to Mala s 6 in patients suffering from allergic rhinitis. In patients with severe form of atopic dermatitis (AD), a very high level of specific IgE was recorded to Mala s 11 (in 36%) and to Asp f 6 (in 12%).

Cutaneous Malassezia: Commensal, Pathogen, or Protector?

The skin microbial community is a multifunctional ecosystem aiding prevention of infections from transient pathogens, maintenance of host immune homeostasis, and skin health. A better understanding of the complex milieu of microbe-microbe and host-microbe interactions will be required to define the ecosystem's optimal function and enable rational design of microbiome targeted interventions. Malassezia, a fungal genus currently comprising 18 species and numerous functionally distinct strains, are lipid-dependent basidiomycetous yeasts and integral components of the skin microbiome. The high proportion of Malassezia in the skin microbiome makes understanding their role in healthy and diseased skin crucial to development of functional skin health knowledge and understanding of normal, healthy skin homeostasis. Over the last decade, new tools for Malassezia culture, detection, and genetic manipulation have revealed not only the ubiquity of Malassezia on skin but new pathogenic roles in seborrheic dermatitis, psoriasis, Crohn's disease, and pancreatic ductal carcinoma. Application of these tools continues to peel back the layers of Malassezia/skin interactions, including clear examples of pathogenicity, commensalism, and potential protective or beneficial activities creating mutualism. Our increased understanding of host- and microbe-specific interactions should lead to identification of key factors that maintain skin in a state of healthy mutualism or, in turn, initiate pathogenic changes. These approaches are leading toward development of new therapeutic targets and treatment options. This review discusses recent developments that have expanded our understanding of Malassezia's role in the skin microbiome, with a focus on its multiple roles in health and disease as commensal, pathogen, and protector.

Atopic Dermatitis: Identification and Management of Complicating Factors

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease, associated with impaired skin barrier function and an atopic background. Various complicating factors, such as irritants, aeroallergens, food, microbial organisms, contact allergens, sweat, and scratching can induce the development of AD symptoms. Irritants, including soap/shampoo and clothes, can cause itching and eczematous lesions. In addition, young children with AD tend to become sensitized to eggs, milk, or peanuts, while older children and adults more often become sensitized to environmental allergens, such as house dust mites (HDM), animal dander, or pollen. Serum-specific IgE levels and skin prick test reactions to food tend to show high negative predictive values and low specificity and positive predictive values for diagnosing food allergy. On the other hand, AD adult patients tend to have severe skin symptoms and exhibit high HDM-specific IgE levels. Microbial organisms, e.g., Staphylococcus aureus and Malassezia furfur, might contribute to the pathogenetic mechanisms of AD. While sweat plays a major role in maintaining skin homeostasis, it can become an aggravating factor in patients with AD. Furthermore, scratching often exacerbates eczematous lesions. Several patient-specific complicating factors are seen in most cases. The identification and management of complicating factors are important for controlling AD.

Malassezia-Associated Skin Diseases, the Use of Diagnostics and Treatment

Yeasts of the genus, Malassezia, formerly known as Pityrosporum, are lipophilic yeasts, which are a part of the normal skin flora (microbiome). Malassezia colonize the human skin after birth and must therefore, as commensals, be normally tolerated by the human immune system. The Malassezia yeasts also have a pathogenic potential where they can, under appropriate conditions, invade the stratum corneum and interact with the host immune system, both directly but also through chemical mediators. The species distribution on the skin and the pathogenetic potential of the yeast varies between different Malassezia related diseases such as head and neck dermatitis, seborrheic dermatitis, pityriasis versicolor, and Malassezia folliculitis. The diagnostic methods used to confirm the presence of Malassezia yeasts include direct microcopy, culture based methods (often a combination of morphological features of the isolate combined with biochemical test), molecular based methods such as Polymerase Chain Reaction techniques, and Matrix Assisted Laser Desorption/Ionization—Time Of Flight mass spectrometry and the chemical imprint method Raman spectroscopy. Skin diseases caused by Malassezia are usually treated with antifungal therapy and if there are associated inflammatory skin mechanisms this is often supplemented by anti-inflammatory therapy. The aim of this paper is to provide an overview of Malassezia related skin disease, diagnostic methods and treatment options.

The role of bacterial skin infections in atopic dermatitis: expert statement and review from the International Eczema Council Skin Infection Group

Patients with atopic dermatitis (AD) have an increased risk of bacterial skin infections, which cause significant morbidity and, if untreated, may become systemic. Staphylococcus aureus colonizes the skin of most patients with AD and is the most common organism to cause infections. Overt bacterial infection is easily recognized by the appearance of weeping lesions, honey‐coloured crusts and pustules. However, the wide variability in clinical presentation of bacterial infection in AD and the inherent features of AD – cutaneous erythema and warmth, oozing associated with oedema, and regional lymphadenopathy – overlap with those of infection, making clinical diagnosis challenging. Furthermore, some features may be masked because of anatomical site‐ and skin‐type‐specific features, and the high frequency of S. aureus colonization in AD makes positive skin swab culture of suspected infection unreliable as a diagnostic tool. The host mechanisms and microbial virulence factors that underlie S. aureus colonization and infection in AD are incompletely understood. The aim of this article is to present the latest evidence from animal and human studies, including recent microbiome research, to define the clinical features of bacterial infections in AD, and to summarize our current understanding of the host and bacterial factors that influence microbial colonization and virulence.

European task force on atopic dermatitis position paper: treatment of parental atopic dermatitis during preconception, pregnancy and lactation period

Atopic dermatitis (AD) is a common inflammatory skin disease that affects both children and adults, including a large number of adults of reproductive age. Several guidelines for the treatment of AD exist, yet specific recommendations for the treatment of pregnant or lactating women and for adults planning to have a child are often lacking. This position paper from the European Task force on Atopic Dermatitis (ETFAD) is based on up-to-date scientific literature on treating pregnant and lactating women as wells as adults with AD planning to have a child. It is based on the expert opinions of members of the ETFAD and on existing safety data on the proposed treatments, many of which are derived from patients with other inflammatory diseases or from transplantation medicine. For treating future parents, as well as pregnant and lactating women with AD, the use of topical treatments including moisturizers, topical corticosteroids, tacrolimus, antiseptics such as chlorhexidine, octenidine, potassium permanganate and sodium hypochlorite (bleach) is deemed to be safe. Ultraviolet (UV) therapy may also be used. Systemic treatment should be prescribed only after careful consideration. According to the opinion of the ETFAD, treatment should be restricted to systemic corticosteroids and cyclosporine A, and, in selected cases, azathioprine.

Phenotypes of atopic dermatitis identified by cluster analysis in early childhood

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

The Role of Fungi in Atopic Dermatitis

There is little doubt that Malassezia spp plays a role in atopic dermatitis because it may interact with the local skin immune responses and barrier function, and sensitization against this skin-colonizing yeast can correlate with disease activity. Also, antifungal therapy shows beneficial effects in some patients. However, the pathogenetic mechanism and mutual interaction between Malassezia spp and atopic dermatitis still remain partly unclear and need further investigation.

Host Responses to Malassezia spp. in the Mammalian Skin

The skin of mammalian organisms is home for a myriad of microbes. Many of these commensals are thought to have beneficial effects on the host by critically contributing to immune homeostasis. Consequently, dysbiosis can have detrimental effects for the host that may manifest with inflammatory diseases at the barrier tissue. Besides bacteria, fungi make an important contribution to the microbiota and among these, the yeast Malassezia widely dominates in most areas of the skin in healthy individuals. There is accumulating evidence that Malassezia spp. are involved in a variety of skin disorders in humans ranging from non- or mildly inflammatory conditions such as dandruff and pityriasis versicolor to more severe inflammatory skin diseases like seborrheic eczema and atopic dermatitis. In addition, Malassezia is strongly linked to the development of dermatitis and otitis externa in dogs. However, the association of Malassezia spp. with such diseases remains poorly characterized. Until now, studies on the fungus–host interaction remain sparse and they are mostly limited to experiments with isolated host cells in vitro. They suggest a multifaceted crosstalk of Malassezia spp. with the skin by direct activation of the host via conserved pattern recognition receptors and indirectly via the release of fungus-derived metabolites that can modulate the function of hematopoietic and/or non-hematopoietic cells in the barrier tissue. In this review, we discuss our current understanding of the host response to Malassezia spp. in the mammalian skin.

Malassezia Yeast and Cytokine Gene Polymorphism in Atopic Dermatitis

INTRODUCTION

Atopic Dermatitis (AD) is a recurrent chronic condition associated with microorganism and their interaction with the susceptible host. Malassezia yeast is a known commensal which is thought to provoke the recurrent episodes of symptoms in atopic dermatitis patients. Malassezia immunomodulatory properties along with defective skin barrier in such host, results in disease manifestation. Here, we studied Single Nucleotide Polymorphism (SNP) in IL10 and IFN γ genes of the host and its relation with susceptibility to Malassezia infection.

AIM

To isolate Malassezia yeast from AD patients and compare the genetic susceptibility of the host by correlating the cytokine gene polymorphism with the control subjects.

MATERIALS AND METHODS

Study was conducted from January 2012 to January 2013. It was a prospective observational study done in Department of Microbiology and Department of Dermatology and Venereology in University College of Medical Sciences and GTB Hospital, Delhi. Sample size comprised of 38 cases each of AD. Skin scrapings were used for fungal culture on Sabouraud Dextrose Agar (SDA) and Modified Dixon Agar (MDA) and isolated were identified as per conventional phenotypic methods. Genomic DNA was extracted from blood samples collected from all study subjects. Cytokine genotyping was carried out by Amplification Refractory Mutations System- Polymerase Chain Reaction (ARMS-PCR) with sequence specific primers. Three SNPs (IL10-1082A/G; IL10-819/592C/T; IFN-γ+874A/T) in two cytokine genes were assessed in all the patients and healthy controls.

STATISTICAL ANALYSIS

Chi-Square Test or Fisher's-Exact Test and Bonferroni's correction.

RESULTS

In AD group, Malassezia yeasts were cultured in 24 out of 38 samples and thus the identification rate was 63.1 percent as compared to healthy group, 52.6 percent (20/38). Significant difference in allele, or genotype distribution were observed in IL10-819/592C/T and IFN-γ+874A/T gene polymorphism in AD group.

CONCLUSION

Higher isolation rate in cases as compared to control group highlights the implication of Malassezia in AD. Association between specific cytokine gene polymorphism and clinical outcome was found to be significant in study group. The result of cytokine gene polymorphism in the present study demonstrated susceptibility of host to Malassezia infection.

Malassezia species and their associated skin diseases

Malassezia spp. are lipophilic fungi that occur on all skin surfaces of humans and animals as commensal and pathogenic organisms. In the 2000s, several new species were added to the Malassezia genus by Japanese researchers. The genus Malassezia now includes 14 species of basidiomycetous yeast. Culture-independent molecular analysis clearly demonstrated that the DNA of Malassezia spp. was predominantly detected in core body and arm sites, suggesting that they are the dominant fungal flora of the human body. Malassezia spp. have been implicated in skin diseases including pityriasis versicolor (PV), Malassezia folliculitis (MF), seborrheic dermatitis (SD) and atopic dermatitis (AD). While Malassezia spp. are directly responsible for the infectious diseases, PV and MF, they act as an exacerbating factor in AD and SD. The fatty acids generated by Malassezia lipase can induce inflammation of the skin, resulting in development of SD. Patch and serum immunoglobulin E tests revealed that AD patients were hypersensitive to Malassezia. However, these findings only partially elucidated the mechanism by which Malassezia spp. induce inflammation in the skin; understanding of the pathogenetic role of Malassezia spp. in SD or AD remains incomplete. In this article, the latest findings of Malassezia research are reviewed with special attention to skin diseases.

Environmental risk factors and their role in the management of atopic dermatitis

INTRODUCTION

The etiology of atopic dermatitis (AD) is multifactorial with interaction between genetics, immune and environmental factors. Areas covered: We review the role of prenatal exposures, irritants and pruritogens, pathogens, climate factors, including temperature, humidity, ultraviolet radiation, outdoor and indoor air pollutants, tobacco smoke exposure, water hardness, urban vs. rural living, diet, breastfeeding, probiotics and prebiotics on AD. Expert commentary: The increased global prevalence of AD cannot be attributed to genetics alone, suggesting that evolving environmental exposures may trigger and/or flare disease in predisposed individuals. There is a complex interplay between different environmental factors, including individual use of personal care products and exposure to climate, pollution, food and other exogenous factors. Understanding these complex risk factors is crucial to developing targeted interventions to prevent the disease in millions. Moreover, patients require counseling on optimal regimens for minimization of exposure to irritants and pruritogens and other harmful exposures.

Immediate Wheal Reactivity to Autologous Sweat in Atopic Dermatitis Is Associated with Clinical Severity, Serum Total and Specific IgE and Sweat Tryptase Activity

BACKGROUND

Sweating can worsen atopic dermatitis (AD). The purpose of this work was to study the associations between reactivity to autologous sweat and the clinical severity of AD as well as investigate the possible wheal-inducing factors of sweat.

METHODS

Intracutaneous skin tests with autologous sweat were performed on 50 AD patients and 24 control subjects. In skin biopsies, tryptase and PAR-2 were enzyme and immunohistochemically stained. The associations between skin test reactivity and sweat histamine concentration, tryptase or chymase activity levels, tryptase or PAR-2 expression and AD clinical severity or IgE levels were investigated.

RESULTS

The wheal reactions in the intracutaneous tests with autologous sweat were positive, weakly positive and negative in 38, 34 and 28% of the AD patients, respectively, and in 4, 46 and 50% of the healthy controls, respectively (p = 0.008). In AD, the wheal reaction was associated significantly with clinical severity, serum total and specific IgE levels and sweat tryptase activity, but not with sweat histamine and chymase. In nonlesional AD skin, the percentage of PAR-2+ mast cells (MCs) or the number of tryptase+ MCs did not differ significantly between the intracutaneous test reactivity groups.

CONCLUSION

Reactivity to autologous sweat correlates with the clinical severity of AD, and tryptase may be one of the factors involved in the sweat-induced wheal.

IgE Sensitization Profiles Differ between Adult Patients with Severe and Moderate Atopic Dermatitis

Background

Atopic dermatitis (AD) is a complex chronic inflammatory disease where allergens can act as specific triggering factors.

Aim

To characterize the specificities of IgE-reactivity in patients with AD to a broad panel of exogenous allergens including microbial and human antigens.

Methodology

Adult patients with AD were grouped according to the SCORAD index, into severe (n = 53) and moderate AD (n = 126). As controls 43 patients were included with seborrhoeic eczema and 97 individuals without history of allergy or skin diseases. Specific IgE reactivity was assessed in plasma using Phadiatop^®, ImmunoCap^™, micro-arrayed allergens, dot-blotted recombinant Malassezia sympodialis allergens, and immune-blotted microbial and human proteins.

Results

IgE reactivity was detected in 92% of patients with severe and 83% of patients with moderate AD. Sensitization to cat allergens occurred most frequently, followed by sensitization to birch pollen, grass pollen, and to the skin commensal yeast M. sympodialis. Patients with severe AD showed a significantly higher frequency of IgE reactivity to allergens like cat (rFel d 1) and house dust mite (rDer p 4 and 10), to Staphylococcus aureus, M. sympodialis, and to human antigens. In contrast, there were no significant differences in the frequencies of IgE reactivity to the grass pollen allergens rPhl p 1, 2, 5b, and 6 between the two AD groups. Furthermore the IgE reactivity profile of patients with severe AD was more spread towards several different allergen molecules as compared to patients with moderate AD.

Conclusion

We have revealed a hitherto unknown difference regarding the molecular sensitization profile in patients with severe and moderate AD. Molecular profiling towards allergen components may provide a basis for future investigations aiming to explore the environmental, genetic and epigenetic factors which could be responsible for the different appearance and severity of disease phenotypes in AD.

EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

The Role of Malassezia spp. in Atopic Dermatitis

Malassezia spp. is a genus of lipophilic yeasts and comprises the most common fungi on healthy human skin. Despite its role as a commensal on healthy human skin, Malassezia spp. is attributed a pathogenic role in atopic dermatitis. The mechanisms by which Malassezia spp. may contribute to the pathogenesis of atopic dermatitis are not fully understood. Here, we review the latest findings on the pathogenetic role of Malassezia spp. in atopic dermatitis (AD). For example, Malassezia spp. produces a variety of immunogenic proteins that elicit the production of specific IgE antibodies and may induce the release of pro-inflammatory cytokines. In addition, Malassezia spp. induces auto-reactive T cells that cross-react between fungal proteins and their human counterparts. These mechanisms contribute to skin inflammation in atopic dermatitis and therefore influence the course of this disorder. Finally, we discuss the possible benefit of an anti-Malassezia spp. treatment in patients with atopic dermatitis.

IgE-mediated sensitization to malassezia in atopic dermatitis: more common in male patients and in head and neck type

BACKGROUND

Atopic dermatitis (AD) is a common chronic inflammatory skin disease. Malassezia, the predominant skin microbiota fungus, is considered to exacerbate AD, especially in a subset of patients with head and neck type AD (HNAD). In the present study, the relationship between AD and sensitization to Malassezia antigens was investigated.

METHODS

We assessed 173 patients with AD. The severity of eczema was determined with Eczema Area and Severity Index (EASI); the type of AD, namely, head and neck type, was reported as well. The total serum IgE and specific IgE to Malassezia were determined and correlated with clinical picture of AD, sex, age, and the EASI.

RESULTS

Total IgE was elevated in 77.7% of patients. Specific IgE to Malassezia was positive (≥0.35 kU/L) in 49.1% of patients. Men were significantly more often sensitized to Malassezia antigen (58% of men vs 42% of women; P value, 0.04). Concurrently, 58% of patients with HNAD versus 42% non-HNAD patients had higher levels of specific IgE to Malassezia, this difference being nearly significant (P value, 0.06). Patients with atopy were also more frequently sensitized to Malassezia. No significant relationship between EASI and the level of total IgE or specific IgE to Malassezia was observed.

CONCLUSIONS

In our population, IgE-mediated sensitization was found in up to 49% of all patients with AD, most common in men and in head and neck type.

Recombinant allergen-based provocation testing

Over the last 25 years, recombinant allergens from all important allergen sources have been cloned and are now available as recombinant proteins. These molecules can be produced in practically unlimited amounts without biological or batch-to-batch variability. It has been shown in provocation tests that recombinant allergens have similar clinical effects as their natural counterparts. With the help of these tools it is possible to reveal the precise reactivity profiles of patients and to uncover and differentiate cross-reactivity from genuine sensitization to an allergen source. Although it has been shown some time ago that it would be possible to replace crude allergen extracts with recombinant allergens for skin prick testing, and even though the use of allergen components can improve routine diagnosis, these tools are still not available for clinical routine applications. The use of provocation tests is a crucial step in the development of new, hypoallergenic vaccines for therapy of allergic disease. Here we describe important provocation methods (skin prick test, intradermal test, atopy patch test, nasal provocation, colonoscopic provocation test) and give an overview of the clinical provocation studies which have been performed with recombinant allergens so far.

Patch testing for noncontact dermatitis: the atopy patch test for food and inhalants

The atopy patch test (APT) is defined as a patch test procedure to assess delayed type hypersensitivity reactions against those protein allergens known to elicit IgE-mediated type I reactions in atopic patients. This patch test procedure uses intact protein allergens instead of haptens in an optimized test setting and with a special reading key. It may be clinically useful especially for atopic dermatitis, as the currently available test procedures either target the wrong reaction type (type I and not type IV) or use the wrong allergens (haptens and not protein allergen). A positive APT reaction correlates with a positive lymphocyte transformation test and allergen-specific Th2 cells in the peripheral blood. As even small changes in the test procedure influence the sensitivity, specificity, and reproducibility of the APT, the European Task Force on Atopic Dermatitis (ETFAD) has developed a standardized APT technique: Intact protein allergens, purified in petrolatum, are applied in 12-mm-diameter Finn chambers mounted on Scanpor tape for 48 h to non-irritated, non-abraded, or tape-stripped skin of the upper back for 48 h; the evaluation of the test reaction is done after 48 and 72 h using the ETFAD reading key, assessing erythema as well as number and distribution pattern of the papules. The APT may reveal type IV sensitization in patients who are negative for the respective type I tests. Limited availability of the expensive test substances and limited reimbursement is among the factors restricting the routine use of the APT.

Anti-Malassezia-Specific IgE Antibodies Production in Japanese Patients with Head and Neck Atopic Dermatitis: Relationship between the Level of Specific IgE Antibody and the Colonization Frequency of Cutaneous Malassezia Species and Clinical Severity

Atopic dermatitis of the head and neck (HNAD) is recognized as a separate condition. Malassezia, the predominant skin microbiota fungus, is considered to exacerbate atopic dermatitis (AD), especially HNAD. In the present study, we investigated the relationships between the levels of specific IgE antibodies, colonization frequency of eight predominant Malassezia species, and clinical severity in 61 patients with HNAD (26 mild, 24 moderate, and 11 severe cases). As clinical severity increased, the levels of specific IgE antibodies against eight Malassezia species also increased. Species diversity of the Malassezia microbiota in scale samples from patients was analyzed by nested PCR using species-specific primers. The clinical severity of HNAD was correlated with the total level of specific IgE antibodies against Malassezia species and the number of Malassezia species detected.

The infectious aspects of atopic dermatitis

Atopic dermatitis is characterized by Staphylococcus aureus colonization and recurrent skin infections. In addition to an increased risk of invasive infections by herpes simplex or vaccinia viruses, there is ample evidence that microbial pathogens, particularly S aureus and fungi, contribute to the cutaneous inflammation of atopic dermatitis. The authors describe recent developments in the pathogenesis of atopic dermatitis in relation to the role of microbial pathogens. Understanding how microbial pathogens interact or evade the cutaneous immunity of atopic dermatitis may be crucial in preventing infections or cutaneous inflammation in this disease.

Mold and human health: separating the wheat from the chaff

The term "mold" is utilized to define the ubiquitous fungal species commonly found in household dust and observed as visible multicellular filaments. Several well-defined human diseases are known to be caused or exacerbated by mold or by exposure to their byproducts. Among these, a solid connection has been established with infections, allergic bronchopulmonary aspergillosis, allergic fungal rhinosinusitis, hypersensitivity pneumonitis, and asthma. In the past decades, other less-defined and generally false conditions have also been ascribed to mold. We will herein review and critically discuss the available evidence on the influence of mold on human health.

Identification of the major allergen of Malassezia globosa relevant for atopic dermatitis

BACKGROUND

Malasseziaglobosa constitutes a part of the normal flora of human skin, but may induce IgE production in atopic dermatitis (AD). However, information on M.globosa allergens is scant.

OBJECTIVE

To identify the major M. globosa allergens by using proteomic analysis.

METHODS

Immunoglobulin E (IgE) immunoblotting and cross-inhibition tests for M. globosa allergens were performed using sera from AD patients and control subjects. These allergens were identified and characterized using the proteomics approach involving a combination of two-dimensional (2D) electrophoresis, mass spectrometry, and bioinformatics tools. We cloned the cDNA of this allergen using sequences obtained by 5'- and 3'-rapid amplification of cDNA ends polymerase chain reaction.

RESULTS

The sera of the AD patients had IgE-reactive 40-45-kDa protein components. By 2D immunoblotting, we detected a 42-kDa protein spot with an isoelectric point (pI) of 4.8; the protein was highly reactive to IgE and was designated MGp42. Full-length MGp42 cDNA contained a 1908-bp open reading frame encoding 635 amino acid residues (calculated molecular mass, 69.7kDa; pI, 6.02). The N-terminal MGp42 sequence started from the 250th residue (Asp-250) of the deduced amino acid sequence and consisted of 386 amino acid residues; these results are consistent with those of 2D immunoblotting. MGp42 showed sequence similarity to members of the heat shock protein 70 (hsp70) family. Immunoblot inhibition tests revealed no IgE cross-reactivity between MGp42 and human HSP70.

CONCLUSIONS

MGp42 may be a cleavage product of intact HSP70. This novel M. globosa allergen could be useful for the diagnosis of AD.

Cross-reactivity among fungal allergens: a clinically relevant phenomenon?

Atopic patients suffering from allergic asthma, allergic rhinitis, or atopic eczema often have detectable levels of serum IgE antibodies to fungi. Although the association between fungal sensitisation and different forms of allergic diseases, including allergic asthma and life-threatening allergic bronchopulmonary aspergillosis, is well established, the clinical relevance of cross-reactivity among different fungal species remains largely unknown. Recent progress in molecular cloning of fungal allergens and the availability of more than 40 completely sequenced fungal genomes facilitates characterisation, cloning, and production of highly pure recombinant allergens, identification of homologous and orthologous allergens widespread among the fungal kingdom, in silico prediction, and experimental in vitro and in vivo verification of cross-reactivity between homologous pan-allergens. These studies indicate that cross-reactivity is an important component of fungal sensitisation.

The role of Malassezia in atopic dermatitis affecting the head and neck of adults

Atopic dermatitis is a common chronic skin condition. A subset of patients with head and neck dermatitis may have a reaction to Malassezia flora fueling their disease. Although there are no documented differences in Malassezia species colonization, patients with head and neck atopic dermatitis are more likely to have positive skin prick test results and Malassezia-specific IgE compared with healthy control subjects and patients with atopy without head and neck dermatitis. There is no clear relationship with atopy patch testing. The reaction to Malassezia is likely related to both humoral- and cell-mediated immunity. Clinically, Malassezia allergy may be suspected in patients with atopic dermatitis and: (1) head and neck lesions; (2) exacerbations during adolescence or young adulthood; (3) severe lesions recalcitrant to conventional therapy; and (4) other atopic diseases. There is literature to suggest that these patients will benefit from a 1- to 2-month course of daily itraconazole or ketoconazole followed by long-term weekly treatment.

Sensitization to the Yeast Malassezia Sympodialis Is Specific for Extrinsic and Intrinsic Atopic Eczema

The opportunistic yeast Malassezia sympodialis belongs to the normal cutaneous flora but can also cause IgE-mediated sensitization in patients suffering from atopic eczema (AE). We investigated 706 individuals by ImmunoCAPm70 and skin-prick tests with a crude M. sympodialis extract. In AE patients, we further performed skin prick tests, atopy patch tests, ELISA, and peripheral blood mononuclear cells proliferation assays with recombinant M. sympodialis allergens (rMala s 1 and 5-9). In 52/97 patients with AE-specific IgE against M. sympodialis was detectable. Almost no reactivity to M. sympodialis was seen in patients suffering from other allergic diseases (4/571) and no reactivity at all was seen in healthy controls (0/38). Skin tests showed variable recognition patterns against the different molecular structures with a predominant sensitization to rMala s 1, 5, 6, and 9, confirmed also by specific serum IgE to these allergens. Interestingly, IgE- and T-cell-mediated reactivity against M. sympodialis was also found in patients with the intrinsic form of AE. Thus, sensitization to M. sympodialis is specific for AE patients and occurs in both the extrinsic and intrinsic variant of eczema. Recombinant yeast allergens represent a useful tool to study molecular structures and differential sensitization patterns in the pathogenesis of AE.

Patch test responses to Malassezia pachydermatis in healthy basset hounds and in basset hounds with Malassezia dermatitis

The effects of the patch test application of Malassezia pachydermatis extracts were evaluated in seven healthy basset hounds and in seven basset hounds with Malassezia dermatitis. Antigens (4 and 0.4 mg/ml) and saline controls were applied for 48 h using filter paper discs in Finn chambers. One healthy basset hound and five affected hounds showed positive patch test reactivity to the yeast antigens. Positive patch test reactions were characterized histologically by mild epidermal hyperplasia and mild to moderate perivascular, periadnexal and interstitial infiltrates of neutrophils and CD3+ lymphocytes. Immediate intradermal test reactivity to M. pachydermatis antigens was seen in one healthy and one affected hound, whereas delayed intradermal test reactivity was seen in six healthy hounds and five affected hounds. This study indicates that patch test reactivity to M. pachydermatis antigen may occur in healthy basset hounds, and in contrast to delayed intradermal test reactivity, is more frequent in basset hounds with Malassezia dermatitis.

Recent developments in the immunology and biology ofMalasseziaspecies

Malassezia spp. are members of the normal cutaneous flora, but are also associated with several cutaneous diseases. Recent studies of the interaction of Malassezia spp. with melanocytes, fibroblasts, keratinocytes and dendritic cells have highlighted their potential to modulate the immune response directed against them. In normal skin they may downregulate the inflammatory response, allowing them to live as commensals. In contrast, in atopic/eczema dermatitis syndrome and psoriasis, they may elicit an inflammatory response that contributes to the maintenance of lesions. Future research may define ways to influence this inflammatory cycle and hence to control or prevent exacerbations of these diseases.

Updates from the British Association of Dermatologists 85th annual meeting, 5-8 July 2005, Glasgow, U.K

The conference highlighted the progress made in understanding recent biological, epidemiological and therapeutic advances in dermatology. Here we provide a synopsis of the main research and clinical findings presented at the meeting of the British Association of Dermatologists (BAD) held during 5-8 July 2005, in Glasgow, U.K., drawing attention to the most important advances and summaries. The BAD meeting was held at the Scottish Exhibition and Conference Centre, Glasgow (Fig. 1). The annual dinner was held in the wonderful setting of Stirling Castle, with Dr Robin Graham-Brown as host.

[Atopy patch testing with aeroallergens and food]

The atopy patch test (APT), a patch test employing allergens known to elicit IgE-mediated reactions which is assessed by evaluating eczematous skin lesions after 24 h to 72 h, was developed as a diagnostic tool for characterizing patients with aeroallergen-triggered atopic eczema (AE, atopic dermatitis). Positive APT reactions are associated with allergen-specific T-cell responses. The specificity of APT is higher than the specificity of skin prick tests or RAST. More studies for the standardization of APT methods are necessary, especially with regard to food APT.

Treatment of head and neck dermatitis with ciclopiroxolamine cream--results of a double-blind, placebo-controlled study

In atopic dermatitis, microbial allergens may be pathogenetically significant. Apart from Staphylococcus aureus, these are primarily lipophilic Malassezia yeasts. They are particularly involved in the pathogenesis of head and neck dermatitis (HND), a special form of atopic dermatitis, which is often difficult to treat. Fifty patients (21 men, 29 women) with moderate to severe HND of at least 6 months' duration were included in a prospective double-blind study. All of them showed at least 10% involvement of the head-neck region. The severity of disease was evaluated by Investigator Global Assessment (IGA), Eczema Area and Severity Index (EASI) for the head-neck region and a pruritus score. IgE antibodies to Malassezia sympodialis and/or Malassezia furfur (at least CAP class 1) were a prerequisite for study enrollment. Either 1% ciclopiroxolamine cream (Batrafen; Aventis Pharma, Bad Soden, Germany) or the corresponding base cream were thinly applied to the affected areas twice daily for 28 days. Sixteen patients in the ciclopiroxolamine group and 13 patients in the placebo group completed the study. To assess the change in severity of atopic eczema, IGA differences between the individual measuring points were determined for all patients. There were significant differences in the IGA score change between the ciclopiroxolamine group and the placebo group, from t3 to t4, and over the total period. Similar, but not significant, changes were observed with the EASI score, in terms of affected skin area and itching. The present study is the first to examine the effect of antifungal single-drug therapy with a cream containing ciclopiroxolamine on the course of HND. The study medication was found to be significantly effective. To optimize this effect, suitable patients selected in terms of fungal load, specific IgE, prick test and particularly atopy patch test for Malassezia antigens could receive combined treatment with antimycotic-containing shampoos and/or short-term systemic antimycotic therapy in severe cases.

Malassezia sympodialis differently affects the expression of LL-37 in dendritic cells from atopic eczema patients and healthy individuals

BACKGROUND

Atopic eczema (AE) is a multifactorial disease, which has increased in prevalence. The skin-colonizing yeast Malasezzia sympodialis can induce IgE- and T-cell reactivity in patients with AE. LL-37 is an endogenous peptide antibiotic belonging to the cathelicidin family. The aim of this study was to examine whether exposure to M. sympodialis would affect the expression of LL-37 in dendritic cells.

METHODS

The presence of LL-37 was analyzed in monocyte-derived dendritic cells (MDDCs) generated from healthy individuals and patients with AE by Western blotting and the corresponding cDNA by real-time quantitative RT-PCR. Antibacterial activity was measured with an inhibition zone assay in fractions after reverse phase chromatography.

RESULTS

For the first time we here present data, showing that LL-37 is produced by MDDCs. Notably, the secretion of LL-37 was substantially enhanced in M. sympodialis-exposed MDDCs generated from patients with a high degree of eczema, as measured by SCORAD, compared to healthy controls and patients with a low SCORAD. The relative expression of LL-37 transcript in MDDCs generated from patients was up-regulated after 1 h of exposure to M. sympodialis and declined gradually at the time points analyzed, whereas the transcription was unaffected in the MDDCs of healthy controls.

CONCLUSIONS

Our results suggest that M. sympodialis can trigger the innate immune response differently in patients with AE and healthy individuals. The enhanced LL-37 secretion from the MDDCs in the patients with AE may reflect the severity of their inflammatory response to M. sympodialis.