The Effects of Different Fluences of 1064 nm Q-Switched Nd:YAG Laser on Skin Repair and Skin Barrier Dysfunction in Mice.

Abstract

The purpose of this study was to investigate the effects of different fluences of Q-switched 1064 nm Nd:YAG laser on skin repair and barrier, and clarify its mechanisms. The Q-switched 1064 nm Nd:YAG laser is widely used for rejuvenation, which needs appropriate fluence data to optimize efficacy and minimize side effects, and for elucidation of action mechanism. The dorsal skin of BABL/c mice was administered 0, 1, 1.5, and 2 J/cm2 energy level laser, twice a week for 4 weeks. Immediately, 7, 14, 21, and 28 days after last treatment, the skin elasticity, moisture content, and transepidermal water loss (TEWL) were measured; 7, 14, 21, and 28 days after last treatment, the hydroxyproline content, mRNA level of procollagen types I and III, protein level of keratin-10 (K-10), filaggrin, transforming growth factor beta receptor II (TGFβRII), Smad2, and p65 were detected. Compared with the unirradiated control, the laser treatments decreased skin elasticity immediately, but increased skin moisture content in the 2 J/cm2 group, and then from day 21 to day 28, the skin elasticity, moisture content, hydroxyproline content, and gene expression of types I and III procollagen increased significantly. The TEWL value of the irradiated group significantly increased after irradiation immediately and 7 days after, K-10 and filaggrin were also decreased at 7 days after. The phosphorylation of TGFβRII (p-TGFβRII) increased at days 7 and 21, and phosphorylation of Smad2 (p-Smad2) was induced at 21 days. Irradiation of 1064 nm Q-switched Nd:YAG laser was able to markedly promote repair of mouse skin within 28 days through stimulation of collagen synthesis, with less skin barrier dysfunction, especially at the 1.5 J/cm2 fluence, and the activation of TGFβ1-signaling pathways seemed to play an important role in repair.