Determination of the photoprotective efficacy of a topical sunscreen against UVB-induced DNA damage in human epidermis.
The ability of a chemical sunscreen with a sun protection factor of ten to protect human skin in situ against UVB-induced DNA damage (cyclobutyl thymine dimers) was evaluated. Biopsies were taken from the left buttock of ten human volunteers prior to UVB (280-315 nm) exposure. Subsequently, a sunscreen (n = 6) or vehicle (n = 4) was applied to a delineated area on the right buttock. After a period of 30 min, the entire buttock area was irradiated in a UVB cabin with one minimal erythema dose. Immediately after irradiation, biopsy specimens were obtained from the UVB-exposed sunscreen- or vehicle-treated right buttock and from the non-treated UVB-exposed left buttock. Dimers were assayed in skin sections by immunofluorescence microscopy with a monoclonal antibody against the cyclobutyl thymine dimer. The dimer-specific fluorescence from the epidermal cell nuclei, identified by counterstaining with propidium iodide, was quantified through computer-mediated image processing and analysis in skin sections of one sunscreen-treated and one vehicle-treated volunteer. After a single dose of UVB, significant dimer-specific nuclear fluorescence was observed and measured in the non-treated biopsy specimens. No nuclear fluorescence was observed and very little could be measured in the non-UVB-exposed skin and in the sunscreen-treated UVB-exposed skin respectively, indicating that the sunscreen offered good protection against the induction of cyclobutyl thymine dimers by UVB. This visual scoring is in general semiquantitative, but quantification through computer-mediated image processing was performed in one case for sunscreen-treated skin and in one case for vehicle-treated skin. Both assessments resulted in similar conclusions.(ABSTRACT TRUNCATED AT 250 WORDS)
van Praag
M C
MC
Department of Dermatology, University Medical Centre, Leiden, Netherlands.
Roza
L
L
Boom
B W
BW
Out-Luijting
C
C
Henegouwen
J B
JB
Vermeer
B J
BJ
Mommaas
A M
AM
D000287:Administration, Topical; D000328:Adult; D000911:Antibodies, Monoclonal; D001562:Benzimidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D001565:Benzoates / Q000008:administration & dosage / Q000494:pharmacology*; D001706:Biopsy; D002164:Camphor / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D047188:Chalcones; D004247:DNA / Q000187:drug effects / Q000528:radiation effects*; D004249:DNA Damage; D004338:Drug Combinations; D005455:Fluorescent Antibody Technique; D006801:Humans; D011740:Pyrimidine Dimers / Q000032:analysis; D012867:Skin / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects; D013473:Sunscreening Agents / Q000494:pharmacology*; D014466:Ultraviolet Rays
D000911:Antibodies, Monoclonal; D001562:Benzimidazoles; D001565:Benzoates; D047188:Chalcones; D004338:Drug Combinations; D011740:Pyrimidine Dimers; D013473:Sunscreening Agents; C083318:avobenzone, ensulizole, enzacamene drug combination; D002164:Camphor; D004247:DNA