A full-UV spectrum absorbing daily use cream protects human skin against biological changes occurring in photoaging.
BACKGROUND
There is overwhelming evidence that exposure of human skin to ultraviolet radiations (UVR) leads to the development of cutaneous photoaging and eventually to neoplasia. This study was designed to evaluate in humans the protection afforded by a daily use cream containing a photostable combination of UVB and UVA absorbers (Uvinul N539, Parsol 1789 and Mexoryl SX) providing a continuous absorption through the entire UV spectrum, against damages induced by repeated daily exposure to solar simulated radiation (SSR).


METHODS
Buttock skin of 12 healthy volunteers was exposed 5 days per week for 6 weeks to one minimal erythema dose of solar simulated radiation per exposure. The following parameters in treated and untreated skin were evaluated: erythema, pigmentation, skin hydration, skin microtopography, histology and immunochemistry, and collagen and metalloproteinase (MMP) mRNA levels.


RESULTS
In SSR exposed unprotected skin sites, we observed melanization and changes in the skin hydration and microtopography. The epidermis revealed a significant increase in stratum corneum and stratum granulosum thickness. In the dermis, an enhanced expression of tenascin and a reduced expression of type I pro-collagen were evidenced just below the dermal epidermal junction. Although we were unable to visualize any change in elastic fibers in exposed buttock skin, a slightly increased deposition of lysozyme and alpha 1 antitrypsin on these fibers was observed using immunofluorescence techniques. Furthermore, types I and III collagen mRNA were slightly increased and a significant enhancement (up to 2.8-fold) of MMP-2 mRNA level was observed. The daily use cream was shown to prevent all these biological changes.


CONCLUSIONS
Our results show in vivo that an appropriate full-UV spectrum product significantly reduces the solar-UV-induced skin damage, demonstrating the benefit of daily photoprotection.
Seité
S
S
L'OREAL, Centre de Recherche Charles Zviak, Clichy, France.
Colige
A
A
Piquemal-Vivenot
P
P
Montastier
C
C
Fourtanier
A
A
Lapière
C
C
Nusgens
B
B
D000179:Acrylates / Q000494:pharmacology*; D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001565:Benzoates / Q000494:pharmacology*; D002081:Buttocks; D001892:Camphanes; D002164:Camphor / Q000031:analogs & derivatives* / Q000494:pharmacology; D047188:Chalcones; D004307:Dose-Response Relationship, Radiation; D004338:Drug Combinations; D004548:Elasticity; D004890:Erythema; D016326:Extracellular Matrix Proteins / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008698:Mesylates / Q000494:pharmacology*; D011427:Propiophenones; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000187:drug effects / Q000528:radiation effects*; D012879:Skin Physiological Phenomena / Q000187:drug effects / Q000528:radiation effects; D012880:Skin Pigmentation / Q000187:drug effects / Q000528:radiation effects*; D013451:Sulfonic Acids; D013473:Sunscreening Agents / Q000494:pharmacology*; D014466:Ultraviolet Rays
D000179:Acrylates; D001565:Benzoates; D001892:Camphanes; D047188:Chalcones; D004338:Drug Combinations; D016326:Extracellular Matrix Proteins; D008698:Mesylates; D011427:Propiophenones; D012333:RNA, Messenger; D013451:Sulfonic Acids; D013473:Sunscreening Agents; C075352:terephthalylidene dicamphor sulfonic acid; C088673:octocrylene; D002164:Camphor; C049935:avobenzone