A method for rapid evaluation of photoaging by measuring fluorescence intensity of green fluorescent protein due to elastin promoter activity

Abstract

Background

Photoaging increases the deep furrows of the facial skin. This can be seen histologically as solar elastosis in the upper layer of the dermis. In sunlight, ultraviolet B (UVB) light plays a pivotal role in forming the wrinkles, because it enhances elastin gene expression and matrix metalloproteases (MMPs) at the transcriptional level in dermal fibroblasts. Sunscreens are believed to inhibit UVB-induced wrinkle formation in humans, but few methods have accurately assessed the protective effects of sunscreens in vivo to date. A major reason is that it takes a long time to cause the deep facial lines.

Objective

To develop a rapid and simple in vivo evaluation system, to assess the inhibitory effects of sunscreens against photoaging, a new experimental method was studied.

Methods

The promoter region of the human elastin gene was cloned into a green fluorescent protein (GFP) vector. The plasmid DNA was transfected into 3T3 cells and stable transfectants (3T3/Eln-GFP) were established. These cells were injected into the dorsal skin of nude mice. After UVB irradiation, the GFP fluorescence intensity was measured by fluorescence emission spectroscopy (FEMS) on the dorsal skin of the mouse.

Results

UVB irradiation of 3T3/Eln-GFP cells increased both the fluorescence intensity and the expression of GFP. Increased GFP fluorescence intensity could be measured from the body surface with FEMS at the injected site of the cells after UVB irradiation in vivo.

Conclusion

A rapid and simple evaluation system for human elastin promoter activity by UVB was established, and we propose it to be an useful method for objective assessment of sunscreens designed to prevent wrinkle formation.