Project description:Skin aging is characterized by structural and functional changes that lead to slower wound healing and higher rate of infections, which contribute to age-associated frailty. This likely depends on synergy between alterations in the local microenvironment and stem cell–intrinsic changes, underscored by pro-inflammatory microenvironments that drive pleotropic changes. To date, little is known about the precise nature and origin of the proposed age-associated inflammatory cues, or how they affect different tissue resident cell types. Based on deep single-cell RNA-sequencing of the entire dermal compartment, we now provide a comprehensive understanding of the age-associated changes in all skin cell types. We show a previously unreported skew towards an IL-17–expressing phenotype of Th cells, γδ T cells and innate lymphoid cells in aged skin. Aberrant IL-17 signaling is common to many autoimmune (e.g., rheumatoid arthritis and psoriasis) and chronic inflammatory diseases. Importantly, in vivo blockade of IL-17–triggered signaling during the aging process reduces the pro-inflammatory state by affecting immune and non-immune skin cells of both dermis and epidermis. Strikingly, IL-17 neutralization significantly delays the appearance of age-related traits, such as decreased epidermal thickness, increased cornified layer thickness and ameliorated hair follicle stem cell activation and hair shaft regeneration. Our results indicate that the aged skin shows chronic and persistent signs of inflammation, and that age-associated increased IL-17 signaling could be targeted as a strategy to prevent age-associated skin ailments in elderly.
Project description:Epidermal hyperplasia, a characteristic feature of psoriatic skin lesions, is epigenetically driven by Enhancer of Zeste homolog 2 (EZH2). EZH2 and EZH2-mediated trimethylation of histone H3 lysine 27 (H3K27me3) are both abnormally upregulated in psoriatic lesions. To identify microRNAs that could potentially target these epigenetic regulators we profiled miRNAs from psoriatic lesional skin in comparison with healthy skin. Analysis of the differentially expressed miRNAs revealed miR-101, as one of the most significant miRNA, consistently downregulated in psoriatic lesions compared to the healthy skin. A clear inverse correlation in the expression of miR-101 versus EZH2 was apparent in normal skin versus psoriatic lesional skin indicating that EZH2 is a potential target of miR-101, which was further confirmed by luciferase assay. Investigating the upstream effectors of the miR-101- EZH2 pathway in psoriasis, we identified the pro-inflammatory cytokine IL-17 as regulator of miR-101 expression. Here we propose a model, depicting a pathway triggered by IL-17 – mediated modulation of miR-101 expression, which in turn elicit sustained expression of EZH2, leading to enhanced keratinocyte proliferation and epidermal hyperplasia in psoriasis. Taken together, this indicates that miR-101 is a potential therapeutic target to alleviate the downstream effects of IL-17 mediated epidermal hyperplasia in psoriasis.
Project description:We report global transcriptional profiles of epidermal basal cells from plantar skin of control mice, high fat diet-fed (HFD) mice and aged mice. By RNA-sequencing of FACS-isolated interfollicular epidermal (IFE) basal cells, we revealed that calcium signal-associated genes, which regulate differentiatin of keratinocytes,were enriched in the plantar skin of HFD and aged mice.