Ultraviolet radiation‐induced degradation of dermal extracellular matrix and protection by green tea catechins: a randomised controlled trial

Background: Loss and remodelling of the dermal extracellular matrix are key features of photodamaged human skin. Green tea catechins (GTC) have been explored for their anti-inflammatory and chemopreventive properties but data on the impact of GTC on UVR-induced changes to the dermal matrix are lacking.
Objectives: To investigate the effect of an inflammatory dose of solar-simulated UVR on the human dermal ECM and potential for protection by GTC in a double-blind randomised controlled trial.

Methods: Healthy white Caucasian adults (n=50, skin type I-II, 18-65 years) were randomised to 540mg GTC/50mg vitamin C or placebo twice daily for 12 weeks. Impact of a 3x minimal erythema dose of solar-simulated UVR on the dermal collagen and elastic fibre networks was assessed by histology and immunohistochemistry in all participants at baseline. Impact of GTC supplementation on UVR-induced effects was compared between groups post-supplementation.

Results: Compared to unexposed skin, area of papillary dermis covered by collagen and elastic fibres was significantly lower (P<0.001) in UVR-exposed skin. Significantly less fibrillin-rich microfibrils (P=0.02), fibulin-2 (P<0.001) and fibulin-5 (P<0.001) was seen in UVR-exposed than unexposed skin with procollagen-1 deposition higher (P=0.01). Following GTC supplementation, the UVR-induced change in fibulin-5 was abrogated in the active group but not placebo with no difference between groups for other components.

Conclusions: Acute UVR induced significant changes in the human dermal collagen and elastic fibre networks, while oral GTC conferred specific protection of fibulin-5. Future studies could explore GTC impact on effects of repeated sub-erythemal UVR exposures on human skin.