title: Protective effects of green tea extracts on photoaging and photommunosuppression.
abstract: 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.
authors.affiliation: State Key Department of Dermatology, No. 1 Hospital of China Medical University, Shenyang 110001, China.
authors.forename: Yuan-Hong
authors.initials: YH
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.forename: Hua-Chen
authors.initials: HC
authors.lastname: Wei
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Xu
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Jia
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Xue-Song
authors.initials: XS
authors.lastname: Yang
authors.forename: Guang-Hui
authors.initials: GH
authors.lastname: Dong
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Gao
authors.forename: Hong-Duo
authors.initials: HD
authors.lastname: Chen
mesh_terms: 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*
chemical_list: D016207:Cytokines; D010936:Plant Extracts; D011837:Radiation-Protective Agents