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Background Atopic dermatitis (AD) is driven by the interplay between a dysfunctional epidermal barrier and a skewed cutaneous immune dysregulation. As part of the complex skin barrier dysfunction, abnormalities in lipid organization and microbiome composition have been described. We set out to systematically investigate the composition of the stratum corneum lipidome, skin microbiome and skin physiology parameters at three different body sites in patients with AD and healthy volunteers. Methods We analysed tape strips from different body areas obtained from 10 adults with AD and 10 healthy volunteers matched for FLG mutation status for 361 skin lipid species using the Metabolon mass spectrometry platform. 16S rRNA data were available from all probands. Results Our study showed that the lipid composition differs significantly between body sites and between AD patients and healthy individuals. Ceramide species NS was significantly higher in AD patients compared to healthy volunteers and was also higher in AD patients with a FLG mutation compared to AD patients without a FLG mutation. The correlation analysis of skin lipid alterations with the microbiome showed that Staphylococcus colonization in AD is positively correlated with ceramide subspecies AS, ADS, NS and NDS. Conclusion This is the first study to reveal site-specific lipid alterations and correlations with the skin microbiome in AD

Quantitative proteomics identifies reduced NRF2 activity and mitochondrial dysfunction in Atopic Dermatitis

Atopic Dermatitis (AD) is the most common inflammatory skin disease and characterized by a deficient epidermal barrier and cutaneous inflammation. Genetic studies suggest a key role of keratinocytes in AD pathogenesis, but the alterations in the proteome that occur in the full epidermis have not been defined. Using a pressure-cycling technology and data-independent acquisition approach, we performed quantitative proteomics of epidermis from healthy volunteers and lesional and non-lesional patient skin. Results were validated by targeted proteomics using parallel reaction monitoring mass spectrometry and immunofluorescence staining. Proteins that were differentially abundant in the epidermis of AD vs. control patients reflect the strong inflammation in lesional skin and the defect in keratinocyte differentiation and epidermal stratification that already characterizes non-lesional skin. Most importantly, they reveal impaired activation of the NRF2-antioxidant pathway and reduced abundance of mitochondrial proteins involved in key metabolic pathways in the affected epidermis. Analysis of primary human keratinocytes with siRNA-mediated NRF2 knock-down revealed that the impaired NRF2 activation and mitochondrial abnormalities are partially interlinked. These results provide insight into the molecular alterations in the epidermis of AD patients and identify potential targets for pharmaceutical intervention

Stratum corneum lipidomics analysis reveals altered ceramide profile in atopic dermatitis patients across body sites with correlated changes in skin microbiome

Background Atopic dermatitis (AD) is driven by the interplay between a dysfunctional epidermal barrier and a skewed cutaneous immune dysregulation. As part of the complex skin barrier dysfunction, abnormalities in lipid organization and microbiome composition have been described. We set out to systematically investigate the composition of the stratum corneum lipidome, skin microbiome and skin physiology parameters at three different body sites in patients with AD and healthy volunteers. Methods We analysed tape strips from different body areas obtained from 10 adults with AD and 10 healthy volunteers matched forFLGmutation status for 361 skin lipid species using the Metabolon mass spectrometry platform. 16S rRNA data were available from all probands. Results Our study showed that the lipid composition differs significantly between body sites and between AD patients and healthy individuals. Ceramide species NS was significantly higher in AD patients compared to healthy volunteers and was also higher in AD patients with aFLGmutation compared to AD patients without aFLGmutation. The correlation analysis of skin lipid alterations with the microbiome showed that Staphylococcus colonization in AD is positively correlated with ceramide subspecies AS, ADS, NS and NDS. Conclusion This is the first study to reveal site-specific lipid alterations and correlations with the skin microbiome in AD

Progression of acute-to-chronic atopic dermatitis is associated with quantitative rather than qualitative changes in cytokine responses

© 2019 American Academy of Allergy, Asthma & Immunology Background: Although multiple studies have assessed molecular changes in chronic atopic dermatitis (AD) lesions, little is known about the transition from acute to chronic disease stages, and the factors and mechanisms that shape chronic inflammatory activity. Objectives: We sought to assess the global transcriptome changes that characterize the progression from acute to chronic stages of AD. Methods: We analyzed transcriptome changes in paired nonlesional skin, acute and chronic AD lesions from 11 patients and 38 healthy controls by RNA-sequencing, and conducted in vivo and histological assays to evaluate findings. Results: Our data demonstrate that approximately 74% of the genes dysregulated in acute lesions remain or are further dysregulated in chronic lesions, whereas only 34% of the genes dysregulated in chronic lesions are altered already in the acute stage. Nonlesional AD skin exhibited enrichment of TNF, TH1, TH2, and TH17 response genes. Acute lesions showed marked dendritic-cell signatures and a prominent enrichment of TH1, TH2, and TH17 responses, along with increased IL-36 and thymic stromal lymphopoietin expression, which were further heightened in chronic lesions. In addition, genes involved in skin barrier repair, keratinocyte proliferation, wound healing, and negative regulation of T-cell activation showed a significant dysregulation in the chronic versus acute comparison. Furthermore, our data show progressive changes in vasculature and maturation of dendritic-cell subsets with chronicity, with FOXK1 acting as immune regulator. Conclusions: Our results show that the changes accompanying the transition from nonlesional to acute to chronic inflammation in AD are quantitative rather than qualitative, with chronic AD having heightened TH2, TH1, TH17, and IL36 responses and skin barrier repair mechanisms. These findings provide novel insights and highlight underappreciated pathways in AD pathogenesis that may be amenable to therapeutic targeting

Real-world data on the effectiveness, safety and drug survival of dupilumab: an analysis from the TREATgermany registry

Stölzl D, Sander N, Heratizadeh A, et al. Real-world data on the effectiveness, safety and drug survival of dupilumab: an analysis from the TREATgermany registry. British Journal of Dermatology. 2022;187(6):1022–1024

Effectiveness, safety and drug survival of dupilumab in patients with moderate to severe atopic dermatitis: an interim analysis of the TREATgermany registry

Stölzl D, Boraczynski N, Heratizadeh A, et al. Effectiveness, safety and drug survival of dupilumab in patients with moderate to severe atopic dermatitis: an interim analysis of the TREATgermany registry. Experimental Dermatology. 2022;31(2):E39-E40

Protein-coding variants contribute to the risk of atopic dermatitis and skin-specific gene expression

BACKGROUND: 15% of atopic dermatitis liability-scale heritability could be attributed to 31 susceptibility loci identified by genome-wide association studies, with only three of them (IL13, IL6R, and FLG) resolved to protein-coding variants. OBJECTIVE: We examined whether a significant portion of unexplained atopic dermatitis heritability is further explained by low-frequency and rare variants in gene coding sequence. METHODS: We evaluated common, low-frequency and rare protein-coding variants using exome chip and replication genotype data of 15,574 patients and 377,839 controls, combined with whole transcriptome data on lesional, non-lesional and healthy skin samples of 27 patients and 38 controls. RESULTS: Additional 12.56% (s.e. 0.74%) of atopic dermatitis heritability is explained by rare protein-coding variation. We identified Docking protein 2 (DOK2) and CD200 Receptor 1 (CD200R1) as novel genome-wide significant susceptibility genes. Rare coding variants associated with atopic dermatitis are further enriched in five genes (IL4R, IL13, JAK1, JAK2, TYK2) of the IL13 pathway, all of which are targets for novel systemic atopic dermatitis therapeutics. Multiomics-based network and RNA-Sequencing analysis revealed DOK2 as a central hub interacting, among others, with CD200R1, IL6R and STAT3. Multi-tissue gene expression profile analysis for 53 tissue types from GTEx showed that disease-associated protein-coding variants exert their greatest effect in skin tissues. CONCLUSION: Our discoveries highlight a major role of rare coding variants in atopic dermatitis acting independently of common variants. Further extensive functional studies are required to detect all potential causal variants and to specify the contribution of novel susceptibility genes DOK2 and CD200R1 to overall disease susceptibility

Protein-coding variants contribute to the risk of atopic dermatitis and skin-specific gene expression.

Background: Fifteen percent of atopic dermatitis (AD) liability-scale heritability could be attributed to 31 susceptibility loci identified by using genome-wide association studies, with only 3 of them (IL13, IL-6 receptor [IL6R], and filaggrin [FLG]) resolved to protein-coding variants.Objective: We examined whether a significant portion of unexplained AD heritability is further explained by low-frequency and rare variants in the gene-coding sequence.Methods: We evaluated common, low-frequency, and rare protein-coding variants using exome chip and replication genotype data of 15,574 patients and 377,839 control subjects combined with whole-transcriptome data on lesional, nonlesional, and healthy skin samples of 27 patients and 38 control subjects.Results: An additional 12.56% (SE, 0.74%) of AD heritability is explained by rare protein-coding variation. We identified docking protein 2 (DOK2) and CD200 receptor 1 (CD200R1) as novel genome-wide significant susceptibility genes. Rare coding variants associated with AD are further enriched in 5 genes (IL-4 receptor [IL4R], IL13, Janus kinase 1 [JAK1], JAK2, and tyrosine kinase 2 [TYK2]) of the IL13 pathway, all of which are targets for novel systemic AD therapeutics. Multiomics-based network and RNA sequencing analysis revealed DOK2 as a central hub interacting with, among others, CD200R1, IL6R, and signal transducer and activator of transcription 3 (STAT3). Multitissue gene expression profile analysis for 53 tissue types from the Genotype-Tissue Expression project showed that disease-associated protein-coding variants exert their greatest effect in skin tissues.Conclusion: Our discoveries highlight a major role of rare coding variants in AD acting independently of common variants. Further extensive functional studies are required to detect all potential causal variants and to specify the contribution of the novel susceptibility genes DOK2 and CD200R1 to overall disease susceptibility

Rare variant analysis in eczema identifies exonic variants in DUSP1, NOTCH4 and SLC9A4

Previous genome-wide association studies revealed multiple common variants involved in eczema but the role of rare variants remains to be elucidated. Here, we investigate the role of rare variants in eczema susceptibility. We meta-analyze 21 study populations including 20,016 eczema cases and 380,433 controls. Rare variants are imputed with high accuracy using large population-based reference panels. We identify rare exonic variants in DUSP1, NOTCH4, and SLC9A4 to be associated with eczema. In DUSP1 and NOTCH4 missense variants are predicted to impact conserved functional domains. In addition, five novel common variants at SATB1-AS1/KCNH8, TRIB1/LINC00861, ZBTB1, TBX21/OSBPL7, and CSF2RB are discovered. While genes prioritized based on rare variants are significantly up-regulated in the skin, common variants point to immune cell function. Over 20% of the single nucleotide variant-based heritability is attributable to rare and low-frequency variants. The identified rare/low-frequency variants located in functional protein domains point to promising targets for novel therapeutic approaches to eczema