Abstract
Exposure to ultraviolet-B (UV-B) irradiation causes skin barrier defects. Based on earlier findings that milk phospholipids containing high amounts of sphingomyelin (SM) improved the water content of the stratum corneum (SC) in normal mice, here we investigated the effects of dietary milk SM on skin barrier defects induced by a single dose of UV-B irradiation in hairless mice. Nine week old hairless mice were orally administrated SM (146 mg/kg BW/day) for a total of ten days. After seven days of SM administration, the dorsal skin was exposed to a single dose of UV-B (20 mJ/cm2). Administration of SM significantly suppressed an increase in transepidermal water loss and a decrease in SC water content induced by UV-B irradiation. SM supplementation significantly maintained covalently-bound ω-hydroxy ceramide levels and down-regulated mRNA levels of acute inflammation-associated genes, including thymic stromal lymphopoietin, interleukin-1 beta, and interleukin-6. Furthermore, significantly higher levels of loricrin and transglutaminase-3 mRNA were observed in the SM group. Our study shows for the first time that dietary SM modulates epidermal structures, and can help prevent disruption of skin barrier function after UV-B irradiation.
Highlights
Skin provides an effective barrier between the organism and the environment by helping to reduce the risk of physical, chemical, and microbial damage
We demonstrated for the first time that dietary SM could prevent the disruption of skin barrier function in hairless mice after a single dose of UV-B irradiation
SM administration suppressed a decrease in both the amount of protein-bound ω-hydroxy ceramides and loricrin mRNA levels. These results suggest that changes in epidermal structure markers such as covalentlybound ω-hydroxy ceramide content and cornified envelope (CE) formations seen in in mice fed milk SM might be associated with an improvement in skin barrier defects that are induced by UV-B irradiation
Summary
Skin provides an effective barrier between the organism and the environment by helping to reduce the risk of physical, chemical, and microbial damage. Exposure to ultraviolet-B (UV-B) radiation is a key factor in the initiation of photo-aging, which can be characterized by dryness, wrinkling, and mottled pigmentation [1,2,3]. UV irradiation of mammalian skin disrupts epidermal permeability barrier functions, and is accompanied by an increase in transepidermal water loss (TEWL) [4,5,6] as well as alterations in the stratum corneum (SC) lipid profile [7, 8]. Reduced barrier function appears to be a consequence of inadequate structural conditions in the epidermis. Skin barrier properties are primarily localized in the SC, which is the PLOS ONE | DOI:10.1371/journal.pone.0136377. Skin barrier properties are primarily localized in the SC, which is the PLOS ONE | DOI:10.1371/journal.pone.0136377 August 24, 2015
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