Modulation of tropoelastin and fibrillin‐1 by infrared radiation in human skin in vivo

Abstract

The heat produced by exposure to infrared radiation (IR) has been demonstrated to modulate the expression of tropoelastin and fibrillin-1, the two main components of elastic fibers in human skin in vivo. However, the effect of IR range of radiations on tropoelastin and fibrillin-1 expression has not been thoroughly investigated. Eighteen volunteers were enrolled in this study involving three trials. Time-dependent, dose-dependent and cumulative effects of IR were investigated, respectively. Tropoelastin and fibrillin-1 expression was measured by immunohistochemical staining on skin biopsy samples from volunteers. In addition, we also measured tropoelastin mRNA expression by a real-time RT-polymerase chain reaction. A single dose of IR (2 minimal heating dose) induced a time-dependent increase in tropoelastin expression at the protein level. An inverse correlation was found between the alterations of tropoelastin and fibrillin-1. Furthermore, IR was found to increase tropoelastin expression in a dose-dependent manner at both the mRNA and the protein level. Repeated low doses of IR increased tropoelastin expression and decreased fibrillin-1 expression at the protein level in the dermis. Meanwhile, the number of both fibers along the dermal-epidermal junction was increased. IR can alter the expression of tropoelastin and fibrillin-1, which may result in abnormal elastic fiber formation.