Cholesterol partially rescues the inhibition effect of pravastatin on keratinocytes proliferation by regulating cell cycle relative proteins through AKT and ERK pathway

TRPV4-β-catenin axis is a novel therapeutic target for dry skin-induced chronic itch

Dry skin induced chronic pruritus is an increasingly common and debilitating problem, especially in the elderly. Although keratinocytes play important roles in innate and adaptive immunity and keratinocyte proliferation is a key feature of dry skin induced chronic pruritus, the exact contribution of keratinocytes to the pathogenesis of dry skin induced chronic pruritus is poorly understood. In this study, we generated the acetone-ether-water induced dry skin model in mice and found that epidermal hyperplasia induced by this model is partly dependent on the β-catenin signaling pathway. XAV939, an antagonist of β-catenin signaling pathway, inhibited epidermal hyperplasia in dry skin model mice. Importantly, dry skin induced chronic pruritus also dramatically reduced in XAV939 treated mice. Moreover, acetone-ether-water treatment-induced epidermal hyperplasia and chronic itch were decreased in Trpv4-/- mice. In vitro, XAV939 inhibited hypo-osmotic stress induced proliferation of HaCaT cells, and hypo-osmotic stress induced proliferation of in HaCaT cells and primary cultured keratinocytes were also significantly reduced by blocking TRPV4 function. Finally, thymic stromal lymphopoietin release was examined both in vivo and in vitro, which was significantly inhibited by XAV939 treatment and Trpv4 deficiency, and anti-TSLP antibody treatment significantly decreased AEW-induced scratching behavior. Overall, our study revealed a unique ability of TRPV4 expressing keratinocytes in the skin, which critically mediated dry skin induced epidermal hyperplasia and chronic pruritus, thus provided novel insights into the development of therapies for chronic pruritus in the elderly.

Crosstalk between cholesterol metabolism and psoriatic inflammation

Psoriasis is a chronic autoinflammatory skin disease associated with multiple comorbidities, with a prevalence ranging from 2 to 3% in the general population. Decades of preclinical and clinical studies have revealed that alterations in cholesterol and lipid metabolism are strongly associated with psoriasis. Cytokines (tumor necrosis factor-α (TNF-α), interleukin (IL)-17), which are important in the pathogenesis of psoriasis, have been shown to affect cholesterol and lipid metabolism. Cholesterol metabolites and metabolic enzymes, on the other hand, influence not only the biofunction of keratinocytes (a primary type of cell in the epidermis) in psoriasis, but also the immune response and inflammation. However, the relationship between cholesterol metabolism and psoriasis has not been thoroughly reviewed. This review mainly focuses on cholesterol metabolism disturbances in psoriasis and their crosstalk with psoriatic inflammation.

Homo Sapiens (Hsa)-microRNA (miR)-6727-5p Contributes to the Impact of High-Density Lipoproteins on Fibroblast Wound Healing In Vitro

Chronic, non-healing wounds are a significant cause of global morbidity and mortality, and strategies to improve delayed wound closure represent an unmet clinical need. High-density lipoproteins (HDL) can enhance wound healing, but exploitation of this finding is challenging due to the complexity and instability of these heterogeneous lipoproteins. The responsiveness of primary human neonatal keratinocytes, and neonatal and human dermal fibroblasts (HDF) to HDL was confirmed by cholesterol efflux, but promotion of ‘scrape’ wound healing occurred only in primary human neonatal (HDFn) and adult fibroblasts (HDFa). Treatment of human fibroblasts with HDL induced multiple changes in the expression of small non-coding microRNA sequences, determined by microchip array, including hsa-miR-6727-5p. Intriguingly, levels of hsa-miR-6727-5p increased in HDFn, but decreased in HDFa, after exposure to HDL. Delivery of a hsa-miR-6727-5p mimic elicited repression of different target genes in HDFn (ZNF584) and HDFa (EDEM3, KRAS), and promoted wound closure in HDFn. By contrast, a hsa-miR-6727-5p inhibitor promoted wound closure in HDFa. We conclude that HDL treatment exerts distinct effects on the expression of hsa-miR-6727-5p in neonatal and adult fibroblasts, and that this is a sequence which plays differential roles in wound healing in these cell types, but cannot replicate the myriad effects of HDL.