Transcriptional Profiling of the Epidermal Response to Solar-Simulated Ultraviolet Radiation

OBJECTIVES:

• Determine the global gene expression profiles in epidermal tissue of healthy fair-skinned adults with Fitzpatrick skin type II after exposure to known doses of solar-simulated ultraviolet radiation (ssUVR) (UVA).
• Determine the ability of an FDA-standardized sunscreen to alter ssUVR-induced transcription profiles in vivo in these participants.
• Determine whether the transcriptional profiles of keratinocytes exposed to UVR in cell culture are comparable to the profiles of keratinocytes in skin after similar levels of UVR exposure.

OUTLINE: This is a pilot, dose-response study followed by an in vivo transcriptional profiling study in 2 different groups.

• Pilot study (verification of ultraviolet radiation dose response): Participants are initially exposed to solar-simulated ultraviolet radiation (ssUVR) (UVA) on the back to determine the minimum erythema dose (MED). Between 22-24 hours after exposure, participants undergo shave biopsy from each of the 9 UV exposure sites and 1 unexposed skin site.
• Group 1 (determination of ssUVR and UVA in vivo transcriptional profiles): On day 1, participants are initially exposed to ssUVR on the back to determine the MED. On day 2, participants are exposed to ssUVR (3 sites) and UVA (3 sites) at the MED on the buttocks. Between 22-24 hours after exposure (day 3), participants undergo shave biopsy from each of the 6 UV exposure sites and 2 unexposed skin sites.
• Group 2 (determination of sunscreen-protected in vivo transcriptional profiles): On day 1, participants are initially exposed to ssUVR on the back to determine the MED. On day 2, participants are exposed to ssUVR on unprotected skin (3 sites) and sunscreen-protected skin (3 sites) at the MED on the buttocks. Between 22-24 hours after exposure (day 3), participants undergo shave biopsy from each of the 6 UV exposure sites and 2 unexposed skin sites.

Biopsies from all participants are analyzed by microarray analysis. One of the unexposed epidermal samples is used for primary keratinocyte culture.