Nomenclature of allergic diseases and hypersensitivity reactions: Adapted to modern needs: An EAACI position paper.

The exponential growth of precision diagnostic tools, including omic technologies, molecular diagnostics, sophisticated genetic and epigenetic editing, imaging and nano-technologies and patient access to extensive health care, has resulted in vast amounts of unbiased data enabling in-depth disease characterization. New disease endotypes have been identified for various allergic diseases and triggered the gradual transition from a disease description focused on symptoms to identifying biomarkers and intricate pathogenetic and metabolic pathways. Consequently, the current disease taxonomy has to be revised for better categorization. This European Academy of Allergy and Clinical Immunology Position Paper responds to this challenge and provides a modern nomenclature for allergic diseases, which respects the earlier classifications back to the early 20th century. Hypersensitivity reactions originally described by Gell and Coombs have been extended into nine different types comprising antibody- (I-III), cell-mediated (IVa-c), tissue-driven mechanisms (V-VI) and direct response to chemicals (VII). Types I-III are linked to classical and newly described clinical conditions. Type IVa-c are specified and detailed according to the current understanding of T1, T2 and T3 responses. Types V-VI involve epithelial barrier defects and metabolic-induced immune dysregulation, while direct cellular and inflammatory responses to chemicals are covered in type VII. It is notable that several combinations of mixed types may appear in the clinical setting. The clinical relevance of the current approach for allergy practice will be conferred in another article that will follow this year, aiming at showing the relevance in clinical practice where various endotypes can overlap and evolve over the lifetime.

Allergic conjunctivitis: a risk factor for recurrent herpes simplex virus infections in patients with atopic dermatitis

Background: Patients with atopic dermatitis have an increased risk of herpes simplex virus (HSV) infections. Objectives: We carried out a retrospective, cross-sectional study to investigate the association of disease severity, concomitant atopic diseases and filaggrin mutations with the risk of cutaneous HSV infections in 463 patients with atopic dermatitis. Materials & Methods: The correlation between predisposing factors and HSV infections was analysed using chi-square and Mann Whitney U-tests, and the relationship was further studied with binomial logistic regression to ascertain odds ratios. Results: Allergic conjunctivitis (aOR: 1.770; CI: 1.008-3.109; p = 0.047) and patient age (aOR: 1.022; CI: 1.007-1.036; p = 0.004) showed statistically significant associations with recurrent HSV infections and eczema herpeticum. HSV infections were not linked to severity of atopic dermatitis (p = 0.435) or filaggrin mutation status (p = 0.886). Conclusion: The results highlight the importance for attentiveness of HSV infections in atopic dermatitis patients with concomitant allergic conjunctivitis.

Age-dependent Distribution of Atopic Dermatitis in Primary Care: A Nationwide Population-based Study from Finland.

The burden of atopic dermatitis (AD) appears to be increasing in adult and elderly patients. The aim of this study was to analyse the nationwide database of the Finnish Institute for Health and Welfare regarding the number of patients with AD and of general practitioner consultations in Finland during 2018. The database comprised the main diagnoses of all visits to public primary healthcare. There were 2,094,673 primary care patients (males/females 43.19/56.81%) and 20,905 patients with AD (1.00%) and 24,180 consultations due to AD (0.45%). The highest numbers of patients with AD were in the age groups 0-14 years (9,922 patients, 47.46%) and 15-65 years (9,144 patients, 43.74%). A substantial proportion of patients with AD were aged > 50 years (3,515 patients, 16.81%) or >65 years (1,947 patients, 9.31%). Regression analysis indicated a statistically significant association of age group with patient numbers (p = 0.032) and number of consultations (p = 0.030). There were no differences between direct age group comparisons (p = 0.303), sex (p = 0.389), or number of consultations/patient (p = 0.235). Patients with AD are prevalent in all age groups in Finnish primary care. Patient numbers were also relatively high in groups other than childhood, indicating that age-related distribution in primary care may be shifting to older ages.

Influence of FLG loss-of-function mutations in host-microbe interactions during atopic skin inflammation.

BACKGROUND: Loss-of-function mutations in the filaggrin (FLG) gene directly alter skin barrier function and critically influence atopic inflammation. While skin barrier dysfunction, Th2-associated inflammation and bacterial dysbiosis are well-known characteristics of atopic dermatitis (AD), the mechanisms interconnecting genotype, transcriptome and microbiome remain largely elusive. OBJECTIVE: In-depth analysis of FLG genotype-associated skin gene expression alterations and host-microbe interactions in AD. METHODS: Multi-omics characterization of a cohort of AD patients carrying heterozygous loss-of-function mutations in the FLG gene (ADMut) (n = 15), along with matched wild-type (ADWt) patients and healthy controls. Detailed clinical characterization, microarray gene expression and 16 S rRNA-based microbial marker gene data were generated and analyzed. RESULTS: In the context of filaggrin dysfunction, the transcriptome was characterized by dysregulation of barrier function and water homeostasis, while the lesional skin of ADWt demonstrated the specific upregulation of pro-inflammatory cytokines and T-cell proliferation. S. aureus dominated the microbiome in both patient groups, however, shifting microbial communities could be observed when comparing healthy with non-lesional ADWt or ADMut skin, offering the opportunity to identify microbe-associated transcriptomic signatures. Moreover, an AD core signature with 28 genes, including CCL13, CCL18, BTC, SCIN, RAB31 and PCLO was identified. CONCLUSIONS: Our integrative approach provides molecular insights for the concept that FLG loss-of-function mutations are a genetic shortcut to atopic inflammation and unravels the complex interplay between genotype, transcriptome and microbiome in the human holobiont.

The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria.

This update and revision of the international guideline for urticaria was developed following the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. It is a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the Global Allergy and Asthma European Network (GA²LEN) and its Urticaria and Angioedema Centers of Reference and Excellence (UCAREs and ACAREs), the European Dermatology Forum (EDF; EuroGuiDerm), and the Asia Pacific Association of Allergy, Asthma and Clinical Immunology with the participation of 64 delegates of 50 national and international societies and from 31 countries. The consensus conference was held on 3 December 2020. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell-driven disease that presents with wheals, angioedema, or both. The lifetime prevalence for acute urticaria is approximately 20%. Chronic spontaneous or inducible urticaria is disabling, impairs quality of life, and affects performance at work and school. This updated version of the international guideline for urticaria covers the definition and classification of urticaria and outlines expert-guided and evidence-based diagnostic and therapeutic approaches for the different subtypes of urticaria.

New Key Players in Irritant Contact Dermatitis: Residential Skin Cells and Neutrophils Drive Inflammation.

The chemokine CCL2 is a potential biomarker for progression of inflammatory skin disease. In a new article of the Journal of Investigative Dermatology, Shibuya et al. (2021) use murine experimental models to show that CCL2‒CCR2‒dependent IL-1ß secretion by local skin cells and skin-infiltrating neutrophils are key drivers of skin irritation.

Transcriptomic Profiling of Adult-Onset Asthma Related to Damp and Moldy Buildings and Idiopathic Environmental Intolerance.

A subset of adult-onset asthma patients attribute their symptoms to damp and moldy buildings. Symptoms of idiopathic environmental intolerance (IEI) may resemble asthma and these two entities overlap. We aimed to evaluate if a distinct clinical subtype of asthma related to damp and moldy buildings can be identified, to unravel its corresponding pathomechanistic gene signatures, and to investigate potential molecular similarities with IEI. Fifty female adult-onset asthma patients were categorized based on exposure to building dampness and molds during disease initiation. IEI patients (n = 17) and healthy subjects (n = 21) were also included yielding 88 study subjects. IEI was scored with the Quick Environmental Exposure and Sensitivity Inventory (QEESI) questionnaire. Inflammation was evaluated by blood cell type profiling and cytokine measurements. Disease mechanisms were investigated via gene set variation analysis of RNA from nasal biopsies and peripheral blood mononuclear cells. Nasal biopsy gene expression and plasma cytokine profiles suggested airway and systemic inflammation in asthma without exposure to dampness (AND). Similar evidence of inflammation was absent in patients with dampness-and-mold-related asthma (AAD). Gene expression signatures revealed a greater degree of similarity between IEI and dampness-related asthma than between IEI patients and asthma not associated to dampness and mold. Blood cell transcriptome of IEI subjects showed strong suppression of immune cell activation, migration, and movement. QEESI scores correlated to blood cell gene expression of all study subjects. Transcriptomic analysis revealed clear pathomechanisms for AND but not AAD patients. Furthermore, we found a distinct molecular pathological profile in nasal and blood immune cells of IEI subjects, including several differentially expressed genes that were also identified in AAD samples, suggesting IEI-type mechanisms.

COVID-19 pandemic and allergen immunotherapy-an EAACI survey.

BACKGROUND: As in many fields of medical care, the coronavirus disease 2019 (COVID-19) resulted in an increased uncertainty regarding the safety of allergen immunotherapy (AIT). Therefore, the European Academy of Allergy and Clinical Immunology (EAACI) aimed to analyze the situation in different countries and to systematically collect all information available regarding tolerability and possible amendments in daily practice of sublingual AIT (SLIT), subcutaneous AIT (SCIT) for inhalant allergies and venom AIT. METHODS: Under the framework of the EAACI, a panel of experts in the field of AIT coordinated by the Immunotherapy Interest Group set-up a web-based retrospective survey (SurveyMonkey® ) including 27 standardized questions on practical and safety aspects on AIT in worldwide clinical routine. RESULTS: 417 respondents providing AIT to their patients in daily routine answered the survey. For patients (without any current symptoms to suspect COVID-19), 60% of the respondents informed of not having initiated SCIT (40% venom AIT, 35% SLIT) whereas for the maintenance phase of AIT, SCIT was performed by 75% of the respondents (74% venom AIT, 89% SLIT). No tolerability concern arises from this preliminary analysis. 16 physicians reported having performed AIT despite (early) symptoms of COVID-19 and/or a positive test result for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). CONCLUSIONS: This first international retrospective survey in atopic diseases investigated practical aspects and tolerability of AIT during the COVID-19 pandemic and gave no concerns regarding reduced tolerability under real-life circumstances. However, the data indicate an undertreatment of AIT, which may be temporary, but could have a long-lasting negative impact on the clinical care of allergic patients.

Integrative transcriptome analysis deciphers mechanisms of nickel contact dermatitis.

BACKGROUND: Nickel-induced allergic contact dermatitis (nACD) remains a major occupational skin disorder, significantly impacting the quality of life of suffering patients. Complex cellular compositional changes and associated immunological pathways are partly resolved in humans; thus, the impact of nACD on human skin needs to be further elucidated. METHODS: To decipher involved immunological players and pathways, human skin biopsies were taken at 0, 2, 48, and 96 hours after nickel patch test in six nickel-allergic patients. Gene expression profiles were analyzed via microarray. RESULTS: Leukocyte deconvolution of nACD-affected skin identified major leukocyte compositional changes at 48 and 96 hours, including natural killer (NK) cells, macrophage polarization, and T-cell immunity. Gene set enrichment analysis mirrored cellular-linked functional pathways enriched over time. NK cell infiltration and cytotoxic pathways were uniquely found in nACD-affected skin compared to sodium lauryl sulfate-induced irritant skin reactions. CONCLUSION: These results highlight key immunological leukocyte subsets as well as associated pathways in nACD, providing insights into pathophysiology with the potential to unravel novel therapeutic targets.

COVID-19 pandemic: Practical considerations on the organization of an allergy clinic-An EAACI/ARIA Position Paper.

BACKGROUND: The coronavirus disease 2019 (COVID-19) has evolved into a pandemic infectious disease transmitted by the severe acute respiratory syndrome coronavirus (SARS-CoV-2). Allergists and other healthcare providers (HCPs) in the field of allergies and associated airway diseases are on the front line, taking care of patients potentially infected with SARS-CoV-2. Hence, strategies and practices to minimize risks of infection for both HCPs and treated patients have to be developed and followed by allergy clinics. METHOD: The scientific information on COVID-19 was analysed by a literature search in MEDLINE, PubMed, the National and International Guidelines from the European Academy of Allergy and Clinical Immunology (EAACI), the Cochrane Library, and the internet. RESULTS: Based on the diagnostic and treatment standards developed by EAACI, on international information regarding COVID-19, on guidelines of the World Health Organization (WHO) and other international organizations, and on previous experience, a panel of experts including clinicians, psychologists, IT experts, and basic scientists along with EAACI and the "Allergic Rhinitis and its Impact on Asthma (ARIA)" initiative have developed recommendations for the optimal management of allergy clinics during the current COVID-19 pandemic. These recommendations are grouped into nine sections on different relevant aspects for the care of patients with allergies. CONCLUSIONS: This international Position Paper provides recommendations on operational plans and procedures to maintain high standards in the daily clinical care of allergic patients while ensuring the necessary safety measures in the current COVID-19 pandemic.

Microbial and transcriptional differences elucidate atopic dermatitis heterogeneity across skin sites.

It is well established that different sites in healthy human skin are colonized by distinct microbial communities due to different physiological conditions. However, few studies have explored microbial heterogeneity between skin sites in diseased skin, such as atopic dermatitis (AD) lesions. To address this issue, we carried out deep analysis of the microbiome and transcriptome in the skin of a large cohort of AD patients and healthy volunteers, comparing two physiologically different sites: upper back and posterior thigh. Microbiome samples and biopsies were obtained from both lesional and nonlesional skin to identify changes related to the disease process. Transcriptome analysis revealed distinct disease-related gene expression profiles depending on anatomical location, with keratinization dominating the transcriptomic signatures in posterior thigh, and lipid metabolism in the upper back. Moreover, we show that relative abundance of Staphylococcus aureus is associated with disease severity in the posterior thigh, but not in the upper back. Our results suggest that AD may select for similar microbes in different anatomical locations-an "AD-like microbiome," but distinct microbial dynamics can still be observed when comparing posterior thigh to upper back. This study highlights the importance of considering the variability across skin sites when studying the development of skin inflammation.

Machine-learning-driven biomarker discovery for the discrimination between allergic and irritant contact dermatitis.

Contact dermatitis tremendously impacts the quality of life of suffering patients. Currently, diagnostic regimes rely on allergy testing, exposure specification, and follow-up visits; however, distinguishing the clinical phenotype of irritant and allergic contact dermatitis remains challenging. Employing integrative transcriptomic analysis and machine-learning approaches, we aimed to decipher disease-related signature genes to find suitable sets of biomarkers. A total of 89 positive patch-test reaction biopsies against four contact allergens and two irritants were analyzed via microarray. Coexpression network analysis and Random Forest classification were used to discover potential biomarkers and selected biomarker models were validated in an independent patient group. Differential gene-expression analysis identified major gene-expression changes depending on the stimulus. Random Forest classification identified CD47, BATF, FASLG, RGS16, SYNPO, SELE, PTPN7, WARS, PRC1, EXO1, RRM2, PBK, RAD54L, KIFC1, SPC25, PKMYT, HISTH1A, TPX2, DLGAP5, TPX2, CH25H, and IL37 as potential biomarkers to distinguish allergic and irritant contact dermatitis in human skin. Validation experiments and prediction performances on external testing datasets demonstrated potential applicability of the identified biomarker models in the clinic. Capitalizing on this knowledge, novel diagnostic tools can be developed to guide clinical diagnosis of contact allergies.

Microbe-host interplay in atopic dermatitis and psoriasis.

Despite recent advances in understanding microbial diversity in skin homeostasis, the relevance of microbial dysbiosis in inflammatory disease is poorly understood. Here we perform a comparative analysis of skin microbial communities coupled to global patterns of cutaneous gene expression in patients with atopic dermatitis or psoriasis. The skin microbiota is analysed by 16S amplicon or whole genome sequencing and the skin transcriptome by microarrays, followed by integration of the data layers. We find that atopic dermatitis and psoriasis can be classified by distinct microbes, which differ from healthy volunteers microbiome composition. Atopic dermatitis is dominated by a single microbe (Staphylococcus aureus), and associated with a disease relevant host transcriptomic signature enriched for skin barrier function, tryptophan metabolism and immune activation. In contrast, psoriasis is characterized by co-occurring communities of microbes with weak associations with disease related gene expression. Our work provides a basis for biomarker discovery and targeted therapies in skin dysbiosis.

Prioritizing research challenges and funding for allergy and asthma and the need for translational research-The European Strategic Forum on Allergic Diseases.

The European Academy of Allergy and Clinical Immunology (EAACI) organized the first European Strategic Forum on Allergic Diseases and Asthma. The main aim was to bring together all relevant stakeholders and decision-makers in the field of allergy, asthma and clinical Immunology around an open debate on contemporary challenges and potential solutions for the next decade. The Strategic Forum was an upscaling of the EAACI White Paper aiming to integrate the Academy's output with the perspective offered by EAACI's partners. This collaboration is fundamental for adapting and integrating allergy and asthma care into the context of real-world problems. The Strategic Forum on Allergic Diseases brought together all partners who have the drive and the influence to make positive change: national and international societies, patients' organizations, regulatory bodies and industry representatives. An open debate with a special focus on drug development and biomedical engineering, big data and information technology and allergic diseases and asthma in the context of environmental health concluded that connecting science with the transformation of care and a joint agreement between all partners on priorities and needs are essential to ensure a better management of allergic diseases and asthma in the advent of precision medicine together with global access to innovative and affordable diagnostics and therapeutics.

INfORM: Inference of NetwOrk Response Modules.

Summary: Detecting and interpreting responsive modules from gene expression data by using network-based approaches is a common but laborious task. It often requires the application of several computational methods implemented in different software packages, forcing biologists to compile complex analytical pipelines. Here we introduce INfORM (Inference of NetwOrk Response Modules), an R shiny application that enables non-expert users to detect, evaluate and select gene modules with high statistical and biological significance. INfORM is a comprehensive tool for the identification of biologically meaningful response modules from consensus gene networks inferred by using multiple algorithms. It is accessible through an intuitive graphical user interface allowing for a level of abstraction from the computational steps. Availability and implementation: INfORM is freely available for academic use at https://github.com/Greco-Lab/INfORM. Supplementary information: Supplementary data are available at Bioinformatics online.

Isotretinoin and lymecycline treatments modify the skin microbiota in acne.

Oral retinoids and tetracyclines have a major role in acne treatment. Here, we report for the first time the effect of isotretinoin and lymecycline therapy on the skin microbiota in cheek, back and armpit swab samples of acne vulgaris patients using 16S ribosomal RNA (16S rRNA) gene amplicon sequencing. Propionibacterium acnes was the most common in sebaceous areas of healthy and untreated acne skin and more abundant in back than cheek samples. Five taxa, including a Streptococcus taxon, differed significantly between the cheek samples of healthy controls and acne patients, and acne severity was positively correlated with the abundance of Propionibacterium. Both treatments reduced clinical acne grades and the abundance of Propionibacterium, while the abundance of several other taxa was significantly higher in treated cheek samples compared with untreated ones. Less variation was observed in back samples and none in armpit samples. There were no differences in alpha diversity between control and acne patients in any of the sampled skin areas, but the diversity of the microbiota on the cheek and the back was significantly increased after acne treatments. This study provides insight into the skin microbiota in acne and how it is modulated by systemic acne treatment.