Project description:The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in adaptive cell functions, and highly active in the epidermis. AhR-ligands can accelerate keratinocyte differentiation, but a precise role for AhR in the skin barrier is unknown. We here show that transepidermal water loss (TEWL), a parameter of skin barrier integrity, is high in AhR-deficient (AhR-KO) mice. Experiments with conditionally AhR-deficient mouse lines identified keratinocytes as the major responsible cell population for high TEWL. Electron microscopy showed weaker inter-cellular connectivity in the epidermis of keratinocytes in AhR-KO mice, and gene expression analysis identified many barrier-associated genes as AhR targets. Moreover, AhR-deficient mice had higher inter-individual differences in their microbiome. Interestingly, removing AhR-ligands from the diet of wild-type mice mimicked AhR-deficiency regarding the impaired barrier. Vice versa, re-addition of the plant-derived ligand indole-3-carbinol (I3C) rescued the barrier deficiency even in aged mice. Our results suggest that functional AhR expression is critical for skin barrier integrity and that AhR represents a molecular target for the development of novel therapeutic approaches for skin barrier diseases, including dietary intervention.
Project description:Essential to terrestrial life is the formation of a competent skin barrier that prevents desiccation and entry by harmful substances. A tightly orchestrated series of cellular changes is required for the proper formation of the epidermal permeability barrier. These changes occur in the context of the commensal skin microbiota. Using germ free mice and antibiotic depletion models, we demonstrate the microbiota is necessary for proper differentiation and repair of the barrier. These effects were mediated by keratinocyte signaling through the aryl hydrocarbon receptor (AHR), a xenobiotic receptor that also regulates epidermal differentiation. Murine skin lacking keratinocyte AHR was more susceptible to infection by S. aureus and increased pathology in a model of atopic dermatitis. Topical colonization with a defined consortium of human skin commensals restored barrier competence in germ free skin and during epicutaneous sensitization; these effects were dependent on keratinocyte AHR. We reveal a fundamental role for the commensal skin microbiota in directing skin barrier formation and repair through the AHR, with far-reaching implications for the numerous skin disorders characterized by disrupted epidermal differentiation and/or barrier competence.
Project description:[original Title] Comparison of expression data of primary murine melanocytes from aryl hydrocarbon deficient mice and corresponding wild-type C57BL/6 mice Melanin is produced exclusively by melanocytes and melanogenesis is the vital response to protect skin cells against Ultraviolet B (UVB)-induced DNA damage. The aryl hydrocarbon receptor (AhR) is a transcription factor, which may be involved in the physiological tanning response. Normal murine melanocytes express functional AhR. We tested gene expression in WT versus AhR-deficient mice primary murine melanocytes, isolated from the skin and cultivated for several passages. Skin epidermal cells from 2 individual C57BL/6 mice and 2 individual AhR-deficient mice (deletion of exon2, AhRtm1Bra) were grown for 6-8 weeks in selection medium to propagate melanocytes.
Project description:[original Title] Comparison of expression data of primary murine melanocytes from aryl hydrocarbon deficient mice and corresponding wild-type C57BL/6 mice Melanin is produced exclusively by melanocytes and melanogenesis is the vital response to protect skin cells against Ultraviolet B (UVB)-induced DNA damage. The aryl hydrocarbon receptor (AhR) is a transcription factor, which may be involved in the physiological tanning response. Normal murine melanocytes express functional AhR. We tested gene expression in WT versus AhR-deficient mice primary murine melanocytes, isolated from the skin and cultivated for several passages.
Project description:The study aimed to interrogate whether the 1,4-naphtoquinone derivative lawsone activates the aryl hydrocarbon receptor (AhR) downstream transcriptional program in keratinocytes and is capable of modulating skin homeostasis. The study has been performed on human primary epidermal keratinocytes (HEKs), which represent the first line of defense against exogenous molecules. HEK cells were treated with the vehicle control DMSO (control), stimulated with lawsone or with the TLR2 ligand Pam2CSK4. Transcriptional profiles of HEK cells were studied to investigate the regulation of AhR -related genes, Nrf2-related genes and epidermal differentiation and keratin genes. We demonstrated that lawsone was sensed by keratinocytes and activated AhR. In particular, lawsone efficiently activated the transcriptional program of AhR and promoted keratinocyte differentiation.
Project description:Defects of filaggrin (FLG) compromise epidermal barrier function and represent an important known genetic risk factor for atopic dermatitis (AD), but also for systemic atopy, including allergic sensitization and asthma. A loss of epidermal barrier integrity can provide a significant stress for the keratinocytes in the skin, either due to the increased moisture evaporation from the skin or increased penetration of the antigens and microflora into the lower epidermal layers. To understand the effect of this loss of barrier integrity on keratinocyte function our aim is to analyze the alterations in the transcriptional profile of keratinocytes from Flg-deficient mice.
Project description:This SuperSeries is composed of the following subset Series: GSE15857: The Aryl Hydrocarbon Receptor Regulates Tissue-Specific Dioxin-Dependent and Dioxin-Independent Gene Batteries: Kidney GSE15858: The Aryl Hydrocarbon Receptor Regulates Tissue-Specific Dioxin-Dependent and Dioxin-Independent Gene Batteries: Liver Refer to individual Series