Telomere Protective Effects of a Cyanobacteria Phycocyanin against Blue Light and UV Irradiations: A Skin Anti-Aging and Photo-Protective Agent

Abstract

Background: Cyanobacteria phycocyanins (Cps) have already shown powerful antioxidant properties. In human cells submitted to oxidative stress the telomeres length decrease, the expression of progerin and the activity of mTOR are increased. At our knowledge, there is no published data on Cps correlated with ultraviolet radiation (UV) and blue light effects in human cells regarding telomeres’ length, progerin expression or mTOR1 complex activity. Objectives: In this study, we sought to assess 1) telomeres’ length in newborn human fibroblasts exposed to UV and blue light; 2) progerin production in mature human normal fibroblasts exposed to UV; 3) mTOR1 activation in adult human normal keratinocytes exposed to UV, analyzing the activity of a Cyanobacteria phycocyanin ( Cp ) in these in vitro models. Materials and Methods: Human skin fibroblasts or human normal keratinocytes were cultured—in the absence or in the presence of Cp and submitted to UVB + UVA and blue light irradiations. Telomeres’ length, progerin expression and mTOR1 activity were then assessed by molecular biology and immuno-enzymatic methods. Results: In cultured fibroblasts exposed to irradiations and treated by Cp , telomeres’ shortage and progerin expression were lower compared to irradiated untreated cells. In cultured keratinocytes treated by Cp and exposed to irradiations, the mTOR activity was lower compared to irradiated untreated cells. Conclusions: In these in vitro studies on human skin fibroblasts and on normal human keratinocytes, the cyanobacteria phycocyanin ( Cp ) showed a decrease of damages induced by UV and blue light expressed by telomeres preservation and downregulation of progerin expression and of mTOR activity, thus showing skin anti-aging and photo-protective potential.