IL-17 downregulates filaggrin and affects epidermal barrier function gene expression; potential role in the pathogenesis of atopic eczema
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE27533 | GEO | 2012/11/01
SECONDARY ACCESSION(S): PRJNA138547
REPOSITORIES: GEO
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Project description:Genome-wide analysis of gene expression after stimulation with cytokines to assess the main processes, molecular functions and cellular components affected as well as genes related to skin barrier function. HaCaT cells were exposed to IL-17A (200ng/ml) for 12h. The cells were lysed, total RNA was extracted and microarray study was performed on Illumina HT12 platform.
2012-11-01 | E-GEOD-27533 | biostudies-arrayexpress
Project description:Background: Methotrexate (MTX) is an effective treatment for atopic eczema (AE); however, the mechanism of action remains incompletely understood. MTX is known to induce keratinocyte differentiation, which can occur following DNA damage triggered by external stimuli. Objectives: We sought to investigate the mechanism of action of MTX in AE using a combination of in vitro models and study of AE skin during the early phases of therapy with MTX. Specifically, we investigated the relationship between MTX-induced DNA damage, keratinocyte differentiation, barrier function, filaggrin status and disease activity. Methods: Lesional and non-lesional skin from two AE cohorts and in vitro human 3-D epidermal organoids (living epidermal equivalents – [LEEs]) were used to assess response to MTX. Markers of late keratinocyte differentiation and response to purine/pyrimidine nucleosides were assessed. Keratinocyte DNA damage following MTX was evaluated through measurement of DNA damage markers and transcriptomic analysis. Results: MTX restored barrier function and induced filaggrin and loricrin expression in AE skin and LEE, through a mechanism inhibited by thymidine. MTX-induced DNA damage and DNA damage response signalling pathways in LEE and AE skin which were upstream of keratinocyte differentiation. There was an interaction between gene expression, disease severity (EASI) and FLG status (heterozygotes versus wildtype, e.g. LGALS7, SPINK7). Conclusions: MTX induces key epidermal barrier proteins through thymidine-dependent DNA damage in the absence of inflammatory cells. Findings were associated with improved disease outcomes in AE skin.
2025-06-01 | GSE283265 | GEO
Project description:BackgroundAtopic eczema (AE) is characterized by skin barrier and immune dysfunction. Null mutations in filaggrin (FLG), a key epidermal barrier protein, strongly predispose to AE; however, the precise role of FLG deficiency in AE pathogenesis remains incompletely understood.ObjectivesWe sought to identify global proteomic changes downstream of FLG deficiency in human epidermal living skin-equivalent (LSE) models and validate findings in skin of patients with AE.MethodsDifferentially expressed proteins from paired control (nontargeting control short hairpin RNA [shNT]) and FLG knockdown (FLG knockdown short hairpin RNA [shFLG]) LSEs were identified by means of proteomic analysis (liquid chromatography-mass spectrometry) and Ingenuity Pathway Analysis. Expression of key targets was validated in independent LSE samples (quantitative RT-PCR and Western blotting) and in normal and AE skin biopsy specimens (immunofluorescence).ResultsProteomic analysis identified 17 (P ≤ .05) differentially expressed proteins after FLG knockdown, including kallikrein-7 (KLK7; 2.2-fold), cyclophilin A (PPIA; 0.9-fold), and cofilin-1 (CFL1, 1.3-fold). Differential protein expression was confirmed in shNT/shFLG LSEs; however, only KLK7 was transcriptionally dysregulated. Molecular pathways overrepresented after FLG knockdown included inflammation, protease activity, cell structure, and stress. Furthermore, KLK7 (1.8-fold) and PPIA (0.65-fold) proteins were differentially expressed in lesional biopsy specimens from patients with AE relative to normal skin.ConclusionsFor the first time, we show that loss of FLG in the absence of inflammation is sufficient to alter the expression level of proteins relevant to the pathogenesis of AE. These include proteins regulating inflammatory, proteolytic, and cytoskeletal functions. We identify PPIA as a novel protein with levels that are decreased in clinically active AE skin and show that the characteristic upregulation of KLK7 expression in patients with AE occurs downstream of FLG loss. Importantly, we highlight disconnect between the epidermal proteome and transcriptome, emphasizing the utility of global proteomic studies.
| S-EPMC5667587 | biostudies-literature
Project description:BackgroundLoss-of-function null mutations R501X and 2282del4 in the skin barrier gene, filaggrin (FLG), represent the most replicated genetic risk factors for atopic dermatitis (AD). Associations have not been reported in African ancestry populations. Atopic dermatitis eczema herpeticum (ADEH) is a rare but serious complication of AD resulting from disseminated cutaneous herpes simplex virus infections.ObjectiveWe aimed to determine whether FLG polymorphisms contribute to ADEH susceptibility.MethodsTwo common loss-of-function mutations plus 9 FLG single nucleotide polymorphisms were genotyped in 278 European American patients with AD, of whom 112 had ADEH, and 157 nonatopic controls. Replication was performed on 339 African American subjects.ResultsSignificant associations were observed for both the R501X and 2282del4 mutations and AD among European American subjects (P = 1.46 x 10(-5), 3.87 x 10(-5), respectively), but the frequency of the R501X mutation was 3 times higher (25% vs 9%) for ADEH than for AD without eczema herpeticum (EH) (odds ratio [OR], 3.4; 1.7-6.8; P = .0002). Associations with ADEH were stronger with the combined null mutations (OR, 10.1; 4.7-22.1; P = 1.99 x 10(-11)). Associations with the R501X mutation were replicated in the African American population; the null mutation was absent among healthy African American subjects, but present among patients with AD (3.2%; P = .035) and common among patients with ADEH (9.4%; P = .0049). However, the 2282del4 mutation was absent among African American patients with ADEH and rare (<1%) among healthy individuals.ConclusionThe R501X mutation in the gene encoding filaggrin, one of the strongest genetic predictors of AD, confers an even greater risk for ADEH in both European and African ancestry populations, suggesting a role for defective skin barrier in this devastating condition.
| S-EPMC5103856 | biostudies-literature
Project description:A functional epidermal skin barrier requires the formation of a cornified envelope from terminally differentiating keratinocytes. During this process, multiple genetic and environmental signals coordinately regulate protein expression and tissue differentiation. Here we describe a critical role for hypoxia-inducible factors (HIFs) in the regulation of filaggrin expression and skin barrier formation. Similar to other mammalian tissues, fetal epidermis in mice is normally O2 deprived. Simultaneous deletion of Hif1a and Hif2a in murine epidermis revealed defects in keratinocyte terminal differentiation and epidermal barrier formation. Mice lacking Hif1a and Hif2a in the epidermis exhibited dry flaky skin, impaired permeability barrier, and enhanced sensitivity to cutaneous allergens. These defects were correlated with stratum granulosum attenuation and reduced filaggrin expression. Hypoxic treatment of primary keratinocytes induced filaggrin (Flg) gene expression in a HIF1α- and HIF2α-dependent manner, suggesting that one mechanism by which Hif1a and Hif2a loss causes epidermal barrier defects in mice lies in Flg dysregulation. Therefore, low O2 tension is an essential component of the epidermal environment that contributes to skin development and function.
| S-EPMC4286527 | biostudies-literature
Project description:BackgroundLongitudinal modelling of the presence/absence of current eczema through childhood has identified similar phenotypes, but their characteristics often differ between studies.ObjectivesTo demonstrate that a more comprehensive description of longitudinal pattern of symptoms may better describe trajectories than binary information on eczema presence.MethodsWe derived six multidimensional variables of eczema spells from birth to 18 years of age (including duration, temporal sequencing and the extent of persistence/recurrence). Spells were defined as consecutive observations of eczema separated by no eczema across 5 epochs in five birth cohorts: infancy (first year); early childhood (age 2-3 years); preschool/early school age (4-5 years); middle childhood (8-10 years); adolescence (14-18 years). We applied Partitioning Around Medoids clustering on these variables to derive clusters of the temporal patterns of eczema. We then investigated the stability of the clusters, within-cluster homogeneity and associated risk factors, including FLG mutations.ResultsAnalysis of 7464 participants with complete data identified five clusters: (i) no eczema (51.0%); (ii) early transient eczema (21.6%); (iii) late-onset eczema (LOE; 8.1%); (iv) intermittent eczema (INT; 7.5%); and (v) persistent eczema (PE; 11.8%). There was very-high agreement between the assignment of individual children into clusters when using complete or imputed (n = 15 848) data (adjusted Rand index = 0.99; i.e. the clusters were very stable). Within-individual symptom patterns across clusters confirmed within-cluster homogeneity, with consistent patterns of symptoms among participants within each cluster and no overlap between the clusters. Clusters were characterized by differences in associations with risk factors (e.g. parental eczema was associated with all clusters apart from LOE; sensitization to inhalant allergens was associated with all clusters, with the highest risk in the PE cluster). All clusters apart from LOE were associated with FLG mutations. Of note, the strongest association was for PE [relative risk ratio (RRR) 2.70, 95% confidence interval (CI) 2.24-3.26; P < 0.001] followed by INT (RRR 2.29, 95% CI 1.82-2.88; P < 0.001).ConclusionsClustering of multidimensional variables identified stable clusters with different genetic architectures. Using multidimensional variables may capture eczema development and derive stable and internally homogeneous clusters. However, deriving homogeneous symptom clusters does not necessarily mean that these are underpinned by completely unique mechanisms.
| S-EPMC10733627 | biostudies-literature
Project description: Not available
| S-EPMC1397720 | biostudies-literature
Project description:Classic atopic dermatitis is complicated by asthma, allergic rhinitis, and food allergies, cumulatively referred to as atopic diseases. Recent discoveries of mutations in the filaggrin gene as predisposing factors for atopic diseases have refocused investigators' attention on epidermal barrier dysfunction as a causative mechanism. The skin's barrier function has three elements: the stratum corneum (air-liquid barrier), tight junctions (liquid-liquid barrier), and the Langerhans cell network (immunological barrier). Clarification of the molecular events underpinning epidermal barrier function and dysfunction should lead to a better understanding of the pathophysiological mechanisms of atopic diseases.
| S-EPMC3266780 | biostudies-literature
Project description:Filaggrin status modulates gene transcription, DNA damage and epidermal barrier repair during clinical response to methotrexate in atopic eczema
| PRJNA1192991 | ENA