Project description:Strong inhibition of NF-kB signaling in the epidermis results in spontaneous skin inflammation in mice and men. Since there is evidence for linkage between polymorphisms within the NF-kB signaling pathway and human inflammatory skin phenotypes, we asked whether partial functional inhibition of NF-kB signaling in epidermal keratinocytes can modulate clinically relevant skin inflammation. We therefore mutated rela specifically in the epidermis of mice (RelAE-MUT mice). These mice show no inflammatory phenotype. Induction of contact allergy, but not croton oil induced irritant dermatitis, resulted in stronger ear swelling and increased epidermal thickness in RelAE-MUT mice. Both contact allergen and croton oil treatment led to increase expression of calgranulins A and B (S100A8/ A9) in RelAE-MUT mice. Epidermal hyperproliferation in RelAE-MUT mice was non-cell autonomous since cultured primary epidermal keratinocytes from RelAE-MUT mice showed reduced proliferation compared to controls. These results demonstrate that epidermal RelA specifically regulates DTH-induced skin inflammation. In addition, we here describe an essential but non- specific function of RelA in the protection of epidermal keratinocytes from apoptosis. Our study identifies new functions of NF-kB signaling in the epidermis and corroborates a specific role of epidermal keratinocytes in the regulation of skin inflammation
Project description:We evaluated cutaneous contact hypersensitivity (CHS) in Cnr1-/-/Cnr2-/- animals using the obligate contact allergen 2,4-dinitrofluorobenzene (DNFB), which generates a specific cutaneous T-cell mediated allergic response upon repeated allergen contact. Allergic contact dermatitis affects about 5% of men and 11% of women in industrialized countries and is one of the leading causes for occupational diseases. In an animal model for cutaneous contact hypersensitivity we show that mice lacking both known cannabinoid receptors display exacerbated allergic inflammation. In contrast, fatty acid amide hydrolase deficient mice, which have increased levels of the endocannabinoid anandamide, displayed reduced allergic responses in the skin. Cannabinoid receptor antagonists exacerbated whereas receptor agonists attenuated allergic inflammation. These results demonstrate a protective role of the endocannabinoid system in contact allergy in the skin, and suggest a novel target for therapeutic intervention. Experiment Overall Design: Three wildtype mice (Wt) and three Cnr1-/-/Cnr2-/- (Ko) mice were used. Contact hypersensitivity was determined always at the right ears, which therefore were treated with DNFB (Tr). Left ears of mice were kept untreated and served as control ears (C). A total of 12 hybridizations were performed (2 strains x 2 treatments X 3 biological replicates) in this experiment.
Project description:We evaluated cutaneous contact hypersensitivity (CHS) in Cnr1-/-/Cnr2-/- animals using the obligate contact allergen 2,4-dinitrofluorobenzene (DNFB), which generates a specific cutaneous T-cell mediated allergic response upon repeated allergen contact. Allergic contact dermatitis affects about 5% of men and 11% of women in industrialized countries and is one of the leading causes for occupational diseases. In an animal model for cutaneous contact hypersensitivity we show that mice lacking both known cannabinoid receptors display exacerbated allergic inflammation. In contrast, fatty acid amide hydrolase deficient mice, which have increased levels of the endocannabinoid anandamide, displayed reduced allergic responses in the skin. Cannabinoid receptor antagonists exacerbated whereas receptor agonists attenuated allergic inflammation. These results demonstrate a protective role of the endocannabinoid system in contact allergy in the skin, and suggest a novel target for therapeutic intervention. Keywords: Strain (Wt versus Ko) and disease state (DNFB treated versus control).
Project description:EGFR signaling controls skin development and homeostasis in mice and humans and its deficiency causes severe skin inflammation, which might affect epidermal stem cell behaviour. Here, we describe the inflammation-independent effects of EGFR-deficiency during skin morphogenesis and in adult HFSCs. Expression and alternative splicing analysis of RNAseq data from interfollicular epidermis and outer root sheath indicate that EGFR controls genes involved in epidermal differentiation, but also in centrosome function, DNA damage, cell cycle and apoptosis. Genetic experiments employing p53-deletion in EGFR–deficient epidermis reveal that EGFR signalling exhibits p53-dependent functions in proliferative epidermal compartments, as well as p53–independent functions in differentiated hair shaft keratinocytes. Loss of EGFR leads to absence of Lef1 protein specifically in the innermost epithelial hair layers, resulting in disorganization of medulla cells. Thus, our results uncover important spatial and temporal features of cell-autonomous EGFR functions in the epidermis.
Project description:p-Phenylenediamine (PPD) is a strong contact allergen used in hair dye that is known to cause allergic contact dermatitis (ACD). We investigated the effects of PPD exposure on the skin of occupationally exposed subjects with and without clinical symptoms.
Project description:Epigenetic regulation of gene expression plays a pivotal role in the orchestration of immune responses and may determine the vigor, quality, or longevity of such responses. Chemical allergens can be divided into two categories: skin sensitizing chemicals associated with allergic contact dermatitis, and chemicals that cause sensitization of the respiratory tract and occupational asthma. In mice these are characterized by different T helper (Th) cell responses. To explore the regulation and maintenance of these divergent responses, mice were exposed to 2,4-dinitrochlorobenzene (DNCB; a contact allergen) or trimellitic anhydride (TMA; a respiratory allergen). DNA from draining lymph nodes was processed for methylated DNA immunoprecipitation (MeDIP) followed by hybridization to a whole-genome DNA promoter array. 6319 differently methylated regions (DMR) were identified following DNCB treatment, while 2178 DMRs were measured following TMA treatment, with approximately half of the TMA DMR common to DNCB. When limited to promoter region-associated DMR, 637 genes were uniquely associated with DNCB induced DMR but only 164 genes were unique to TMA DMR. Promoter-associated DMR unique to either DNCB or TMA were generally hypomethylated whereas DMR common to both allergens tended to be hypermethylated. Pathway analyses highlighted a number of immune related pathways, including chemokine and cytokine signalling. These data demonstrate that chemical allergen exposure results in characteristic patterns of DNA methylation indicative of epigenetic regulation of the allergic response. Comparison of methylation profiles from allergens 2,4-dinitrochlorobenzene (DNCB; a contact allergen) and trimellitic anhydride (TMA; a respiratory allergen) or vehicle acetone:olive oil (AOO).
Project description:Atopic dermatitis (AD) is a chronic pruritic inflammatory skin disease. We recently described an animal model in which repeated epicutaneous applications of a house dust mite extract and Staphylococcal enterotoxin B induced eczematous skin lesions. In this study we showed that global gene expression patterns are very similar between human AD skin and allergen/staphylococcal enterotoxin B–induced mouse skin lesions, particularly in the expression of genes related to epidermal growth/differentiation, skin barrier, lipid/energy metabolism, immune response, or extracellular matrix. In this model, mast cells and T cells, but not B cells or eosinophils, were shown to be required for the full expression of dermatitis, as revealed by reduced skin inflammation and reduced serum IgE levels in mice lacking mast cells or T cells (TCRb-/- or Rag1-/-). The clinical severity of dermatitis correlated with the numbers of mast cells, but not eosinophils. Consistent with the idea that T helper type 2 (Th2) cells play a predominant role in allergic diseases, the receptor for the Th2-promoting cytokine thymic stromal lymphopoietin and the high-affinity IgE receptor, FceRI, were required to attain maximal clinical scores. Therefore, this clinically relevant model provides mechanistic insights into the pathogenic mechanism of human AD. A total of six samples were analyzed. Back skin samples from healthy or AD-induced C57BL/6, PLC-beta 3 KO (C57BL/6 background), and NC/Nga mice were collected for total RNA extraction. Pooled RNA from 2-4 mice per condition were used for analysis.
Project description:Atopic dermatitis is a multifactorial allergic skin disease in humans and dogs. Genetic predisposition, immunologic hyperreactivity, a defective skin barrier and environmental factors play a role in its pathogenesis. The aim of this study was to analyze gene expression in the skin of dogs sensitized to house dust mite antigens. Skin biopsies were collected from six sensitized and six non-sensitized Beagle dogs from normal, non-treated skin before and six and 24 hours after challenge using skin patches with allergen or saline as a negative control. Transcriptome analysis was performed by the use of DNA microarrays and expression of selected genes was validated by quantitative real-time RT-PCR. Expression data was compared between groups (unpaired design). After 24 hours 597 differentially expressed genes were detected, 361 with higher and 226 with lower mRNA concentration in allergen treated skin of sensitized dogs compared to their saline-treated skin and compared to the control specimens. Functional annotation clustering, pathway-and co-citation analysis showed, that the genes with increased expression were involved in inflammation, wound healing and immune response. In contrast, genes with decreased expression in sensitized dogs were associated with differentiation and barrier function of the skin. As the sensitized dogs did not show differences in the untreated skin compared to controls, inflammation after allergen patch test probably led to a decrease in the expression of genes important for barrier formation. Our results further confirm the similar pathophysiology of human and canine atopic dermatitis and revealed genes previously not known to be involved in canine atopic dermatitis. 60 canine (dog) skin tissue samples; six sensitized and six non-sensitized Beagle dogs; samples collected before (0h), 6h and 24h after challenge with allergen; samples collected from a skin area treated with saline and from an area treated with allergen
Project description:We analyzed epidermal samples from keratinocyte-specific knockout Mettl3 (K14CreERT2;Mettl3fl/fl) mice and their controls (Mettl3fl/fl) in imiquimod-induced psoriasis-like skin lesions. Briefly, we established an imiquimod-induced psoriasis model in K14CreERT2;Mettl3fl/fl mice and their controls after tamoxifen injection, and epidermal samples were separated and collected from the skin lesions of the mice after 3 or 6 days of modeling (n=3 per group). The aim of this study was to investigate the mechanism by which Mettl3-mediated epidermal m6A methylation affects skin inflammation.
Project description:The skin epidermis provides a vital barrier for preventing transepidermal water loss (TEWL) and environmental stimuli. However, the molecular mechanisms ensuring barrier integrity remain not fully understood. RORα is a nuclear receptor highly expressed in the epidermis of normal skin. However, its epidermal expression is significantly reduced in the lesions of multiple inflammatory skin diseases. In this study, using mice with epidermis-specific Rora gene deletion (RoraEKO), we have demonstrated the central roles of RORα in stabilizing skin barrier function. Albeit the lack of spontaneous skin lesion or dermatitis, RoraEKO mice exhibited elevated TEWL rate and skin features indicating barrier dysfunction. The histological and lipidomic analysis uncovered low levels of cornified envelope proteins and aberrant ceramide composition in the RoraEKO epidermis, implying disturbed late epidermal differentiation. In parallel, RNA-seq analysis revealed altered transcription levels of gene clusters related to “keratinization” and “lipid metabolism” in RORα deficient epidermis. Importantly, epidermal Rora ablation greatly amplified percutaneous allergic inflammatory responses to oxazolone in a mouse allergic contact dermatitis (ACD) model. Our results substantiated the essence of epidermal RORα in maintaining late keratinocyte differentiation and normal barrier function while suppressing cutaneous inflammation.