Establishment of Photoaging In Vitro by Repetitive UVA Irradiation: Induction of Characteristic Markers of Senescence and its Prevention by PAPLAL with Potent Catalase Activity

Abstract

To understand a role of UVA radiation in photoaging of the skin, we established a model of photoaging cells using cultured human dermal fibroblasts. Repeated low-dose UVA radiation for 10 consecutive days induced senescence in fibroblasts, characterized with (1) increased level of senescence-associated β-galactosidase, (2) flattened large cell shape, (3) accumulation of reactive oxygen species, (4) yellowish coloration and (5) expression of p16. These were also observed in chronologically aged fibroblasts (doubling times >20), whereas none of these were detected in young cells (doubling times <10). Collectively, we propose that fibroblasts exposed to repetitive UVA radiation may be a good model of aged cells to study the mechanism of aging and photoaging and further to search for novel agents preventing cellular senescence. In addition, H O was produced in the culture medium by a single low dose of UVA irradiation. Further, PAPLAL, a nanoparticle of platinum and palladium having potent catalase-like activity, significantly delayed the onset of H O -induced cell senescence. The present study strongly indicates that repetitive short-term UVA irradiation induces aging of cells possibly via H O and may be suppressed by potent anti-H O agents.

Riboflavin Plays a Pivotal Role in the UVA-Induced Cytotoxicity of Fibroblasts as a Key Molecule in the Production of H2O2 by UVA Radiation in Collaboration with Amino Acids and Vitamins

“…The cell viability of fibroblasts cultured in DMEM exposed to UVA decreased significantly, but remained at the same level as non-irradiated fibroblasts cultured in DMEM when the DMEM was replaced with fresh DMEM immediately after the UVA exposure ( Figure 1b). We previously reported that H 2 O 2 generated by UVA exposure of DMEM induces the senescence of fibroblasts [19]. Therefore, we studied the effects of catalase and glutathione (GSH) on the viability of UVA-irradiated fibroblasts cultured in DMEM and confirmed the preventive effects of those antioxidants when added to the DMEM prior to exposure with UVA ( Figure 1c).…”

“…We and other research groups have demonstrated that chronic repetitive UVA radiation as well as a single high dose of UVA radiation causes cellular senescence in vitro and contributes to the induction of skin photo-aging in vivo, mostly by the generation of ROS [19,29], particularly H 2 O 2 , which has a long half-life compared with O 2 − and 1 O 2 . To induce biological reactions in the skin, UVA radiation is absorbed by molecules, called endogenous and exogenous chromophores, such as flavins, porphyrins, pterins, urocanic acid, FICZ, heme-oxygenase-1, and NADPH-oxidase.…”

“…The type I mechanism does not require oxygen for the induction of photo-damage, whereas type II mechanisms proceed only in the presence of oxygen [18]. We recently reported that chronic low dose UVA radiation induces the cellular senescence of fibroblasts in vitro at a total dose of 36 J/cm 2 within two weeks, and suggested a pivotal role for hydrogen peroxide (H 2 O 2 ) in the induction of cell senescence, which is produced by UVA absorption and possibly by riboflavin, known as a potent UVA chromophore in the medium [19].…”

A Randomized Study to Determine the Sun Protection Factor of Natural Pterostilbene from Pterocarpus Marsupium

“…UV induced ROS further interferes with the cell signaling pathways resulting in the breakdown of collagen and reduction in collagen synthesis, leading to wrinkles and sagging of skin [52]. Photoaging is an accelerated aging process induced by sun exposure in skin cells [53][54][55]. We observed that pterostilbene could reduce the ROS production triggered by hydrogen peroxide as well as UVA radiations in skin fibroblast cells and protect the cells against oxidative damage and photoaging.…”

Platinum and palladium nanoparticle‐containing mixture, PAPLAL, does not induce palladium allergy

“…Furthermore, PAPLAL directly activates signalling of aryl hydrocarbon receptor (AHR) and NRF2, suggesting its potential application in vitiligo treatment . Yoshimoto et al recently reported that PAPLAL with catalase activity suppresses H 2 O 2 ‐induced cellular senescence . Thus, PAPLAL treatment is expected to show many beneficial effects on oxidative stress‐mediated cellular senescence and skin diseases.…”