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photoaging

Monday 8 September 2014

UV and aging; photoageing

Two types of skin aging have been identified: intrinsic, mainly genetically determined and extrinsic-also called "photo-aging"-resulting on the impact of environmental stress and more precisely of UV rays.

Simplified in vitro models, based on cellular senescence, have been developed to study the relationship between UV and aging. These models vary on the cell type (fibroblasts or keratinocytes, normal or immortalized) and the type of UV used (UVA or UVB).

Photoaging and photocarcinogenesis are primarily due to solar ultraviolet (UV) radiation, which alters DNA, cellular antioxidant balance, signal transduction pathways, immunology, and the extracellular matrix (ECM). The DNA alterations include UV radiation induced thymine-thymine dimers and loss of tumor suppressor gene p53. UV radiation reduces cellular antioxidant status by generating reactive oxygen species (ROS), and the resultant oxidative stress alters signal transduction pathways such as the mitogen-activated protein kinase (MAPK), the nuclear factor-kappa beta (NF-κB)/p65, the janus kinase (JAK), signal transduction and activation of transcription (STAT) and the nuclear factor erythroid 2-related factor 2 (Nrf2). UV radiation induces pro-inflammatory genes and causes immunosuppression by depleting the number and activity of the epidermal Langerhans cells. Further, UV radiation remodels the ECM by increasing matrixmetalloproteinases (MMP) and reducing structural collagen and elastin.

Open references

- Mechanisms of Photoaging and Cutaneous Photocarcinogenesis, and Photoprotective Strategies with Phytochemicals. Bosch R, Philips N, Suárez-Pérez JA, Juarranz A, Devmurari A, Chalensouk-Khaosaat J, González S. Antioxidants (Basel). 2015 Mar 26;4(2):248-68. doi : 10.3390/antiox4020248 PMID: 26783703 (Free)

- UV, stress and aging. Debacq-Chainiaux F, Leduc C, Verbeke A, Toussaint O. Dermatoendocrinol. 2012 Jul 1;4(3):236-40. doi : 10.4161/derm.23652 PMID: 23467762 (Free)