Solar-simulated radiation and heat treatment induced metalloproteinase-1 expression in cultured dermal fibroblasts via distinct pathways: Implications on reduction of sun-associated aging

摘要

Background: Sun exposure is an important environmental factor affecting human beings. Most knowledge regarding solar aging focused on light radiation (photoaging), and little emphasis has been placed on heat, a factor that is also closely associated with sun exposure. Objective: This study was launched to evaluate the effects of simulated solar radiation (SSR) and environmental heat on skin fibroblasts in terms of dermal aging. Methods: Cultured human dermal fibroblasts were treated with moderate amount of SSR (200J/cm2) and heat (+2°C). The metalloproteinase-1 (MMP-1) expression was used as a surrogate marker for dermal aging and the involved regulatory mechanisms were explored. Results: Both treatment conditions did not affect viability but significantly increased the expressions of MMP-1. In parallel, both treatments increased the intracellular levels of reactive oxygen species (ROS), but the increase induced by SSR is much greater than heat. In contrast, transient receptor potential vanilloid 1 (TRPV-1), the sensor of environmental heat, was upregulated by heat but not SSR treatment. Pretreating fibroblasts with antioxidant abrogated the SSR-induced MMP-1 but has limited effect on heat-induced MMP-1. On the other hand, TRPV-1 antagonist pretreatment reduced heat-induced MMP-1 in fibroblasts but not their SSR-treated counterparts. Conclusion: Both SSR and heat induced MMP-1 expression in dermal fibroblasts but through different pathways. As current strategies for reducing sun-related aging focused on filtering of light and use of antioxidants, future strategies design to reduce solar aging should also incorporate heat-induced aging into consideration.