Protective effects of green tea extracts on photoaging and photommunosuppression.
OBJECTIVE
This study aimed to investigate whether the sunscreen-containing 2-5% green tea extracts (GTEs) protect ultraviolet irradiation (UVR)-induced photoaging and photoimmunosuppression.


METHODS
Twenty volunteers were exposed to repetitive solar-simulated UVR (ssUVR) on the upper back at a dosage of 1.5 minimal erythema doses (MED) per day for four consecutive days. Thirty minutes before each UVR and 6, 24, and 48 h after the last UV exposure, the products containing vehicle, and 2-5% GTEs were applied onto five sites on the dorsal skin, respectively. The skin biopsies were obtained 72 h after the last UVR. The thickness of the stratum corneum and epidermis was measured under the microscope and the expression of cytokeratins (CK)-5/6, CK16, metalloproteinases (MMP)-2, MMP-9, and the CD1a(+) Langerhans cells (LCs) were determined using immunohistochemistry.


RESULTS
Our results showed that UVR substantially induced cutaneous erythema, thickening of the epidermis, overexpression of CK5/6, CK16, MMP-2, MMP-9, and depletion of CD1a(+) LCs. The sunscreens containing different concentrations of GTEs conferred significant protection against the photoaging and photoimmunology-related biological events. Interestingly, the protective effects were not parallel to the concentrations of GTEs, with 2% and 3% GTEs showing the most efficacious photoprotection.


CONCLUSIONS
GTEs-containing sunscreens have potential photoprotective effects on UVR-induced photoaging and photoimmunosuppression.
Li
Yuan-Hong
YH
State Key Department of Dermatology, No. 1 Hospital of China Medical University, Shenyang 110001, China.
Wu
Yan
Y
Wei
Hua-Chen
HC
Xu
Yuan-Yuan
YY
Jia
Li-Li
LL
Chen
Jing
J
Yang
Xue-Song
XS
Dong
Guang-Hui
GH
Gao
Xing-Hua
XH
Chen
Hong-Duo
HD
D000328:Adult; D000375:Aging / Q000187:drug effects* / Q000276:immunology*; D028241:Camellia sinensis / Q000737:chemistry*; D016207:Cytokines / Q000276:immunology; D004305:Dose-Response Relationship, Drug; D004890:Erythema / Q000209:etiology* / Q000276:immunology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D010936:Plant Extracts / Q000008:administration & dosage*; D011837:Radiation-Protective Agents / Q000008:administration & dosage; D012993:Solar Energy; D016896:Treatment Outcome; D014466:Ultraviolet Rays / Q000009:adverse effects*
D016207:Cytokines; D010936:Plant Extracts; D011837:Radiation-Protective Agents