Abstract
Background
Although fatty acids are known to be important in various skin functions, their roles
on photoaging in human skin are poorly understood.
Objective
We investigated the alteration of lipid metabolism in the epidermis by photoaging
and acute UV irradiation in human skin.
Methods
UV irradiated young volunteers (21–33 years, n = 6) and elderly volunteers (70–75 years, n = 7) skin samples were obtained by punch biopsy. Then the epidermis was separated from
dermis and lipid metabolism was investigated.
Results
We observed that the amounts of free fatty acids (FFA) and triglycerides (TG) in the
epidermis of photoaged or acutely UV irradiated human skin were significantly decreased.
The expressions of genes related to lipid synthesis, including acetyl-CoA carboxylase
(ACC), fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD), sterol regulatory
element binding proteins (SREBPs), and peroxisome proliferator-activated receptors
(PPARγ) were also markedly decreased. To elucidate the significance of these changes
of epidermal lipids in human skin, we investigated the effects of TG or various inhibitors
for the enzymes involved in TG synthesis on the expression of matrix metalloproteinase-1
(MMP-1) in cultured human epidermal keratinocytes. We demonstrated that triolein (TG)
reduced basal and UV-induced MMP-1 mRNA expression. In addition, each inhibitor for
various lipid synthesis enzymes, such as TOFA (ACC inhibitor), cerulenin (FAS inhibitor)
and trans-10, cis-12-CLA (SCD inhibitor), increased the MMP-1 expression significantly
in a dose-dependent manner. We also demonstrated that triolein could inhibit cerulenin-induced
MMP-1 expression. Furthermore, topical application of triolein (10%) significantly
prevented UV-induced MMP-13, COX-2, and IL-1β expression in hairless mice.
Conclusion
Our results suggest that TG and FFA may play important roles in photoaging of human
skin.
Keywords
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Article info
Publication history
Published online: July 12, 2010
Accepted:
October 19,
2009
Received in revised form:
October 6,
2009
Received:
September 18,
2009
Identification
Copyright
© 2009 Japanese Society for Investigative Dermatology. Published by Elsevier Inc. All rights reserved.
