RESUMO
Several studies have reported the effects of vitamin C (L-ascorbic acid, AA) on ultraviolet B (UVB)-induced cell damage using cultured keratinocytes. However, the epidermis consists of multiple cell layers, and the effect of AA on UVB-induced damage to the human epidermis remains unclear. Therefore, we investigated the effect of AA on UVB-induced skin damage using reconstituted human epidermis. The reconstituted human epidermal surface was treated with 100 and 500 mM AA and cultured for 3 h before (pre-AA treatment) or after (post-AA treatment) 120 mJ/cm2 UVB irradiation. Pre- and post-AA treatments of the epidermal surface suppressed UVB-induced cell death, apoptosis, DNA damage, reactive oxygen species (ROS) production, and the inflammatory response by downregulating tumour necrosis factor-α (TNF-α) expression and release. Moreover, the pre-AA treatment was more effective at preventing UVB-induced skin damage than the post-AA treatment. In summary, pre- and post-AA treatments of the epidermis prevent UVB-induced damage.
Assuntos
Ácido Ascórbico/farmacologia , Queratinócitos/efeitos dos fármacos , Lesões por Radiação/tratamento farmacológico , Pele/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Apoptose/efeitos da radiação , Ácido Ascórbico/metabolismo , Técnicas de Cultura de Células , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , Epiderme/efeitos dos fármacos , Epiderme/metabolismo , Epiderme/patologia , Epiderme/efeitos da radiação , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Queratinócitos/metabolismo , Queratinócitos/patologia , Queratinócitos/efeitos da radiação , Lesões por Radiação/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Pele/lesões , Pele/efeitos da radiação , Fator de Necrose Tumoral alfa/genética , Raios Ultravioleta/efeitos adversosRESUMO
Ascorbic acid (AA) is essential for collagen biosynthesis as a cofactor for prolyl and lysyl hydroxylase and as a stimulus for collagen gene expression. Many studies have evaluated the relationship between AA and collagen expression in short- and long-term effects on cells after a single administration of AA into the culture medium. However, no such study has monitored in detail the stability of AA in medium or the alterations of intracellular AA levels during a protracted interval. Therefore, we examined here intracellular AA levels and stability throughout its exposure to human skin fibroblasts in vitro. Moreover, we determined the effects on type 1 and type 4 collagen and sodium-dependent vitamin C transporter (SVCT) gene expression when medium containing 100 µM AA was replaced every 24h for 5 days to avoid depletion of AA. Throughout this long-term culture, intracellular AA levels remained constant; the expression of type 1 and type 4 collagens and SVCT2 mRNA was enhanced, and type 1 procollagen synthesis increased. Thus, these results indicate that human skin fibroblasts exposed to AA over time had rising levels of type 1/type 4 collagens and SVCT2 mRNA expression and type 1 procollagen synthesis.
