Influence of successive and combined ultraviolet A and B irradiations on matrix metalloelastases produced by human dermal fibroblasts in culture.

Abstract To study the cumulative influence of UV irradiations on skin matrix alterations, human skin fibroblasts were irradiated successively three-fold, at 24 h intervals, with UVA (3×5J/cm 2 ), UVB (3×8mJ/cm 2 ), UVA plus UVB (3×5J/cm 2 and 3×8mJ/cm 2 ) and the levels of 92 kDa gelatinase (pro-MMP 9 ), 72 kDa gelatinase (pro-MMP 2 ) and plasma-membrane elastase type protease were determined, following subsequent 24-h culture in 10% serum-containing medium. UV irradiations had only minor influence (1.4-fold increase for UVB) on secreted levels of pro-MMP 2 and decreased the amount of plasma membrane elastase produced by cells. It did however, for UVA and UVB alone, induce a significant increase of 66 kDa activated MMP 2 production: 2.5- and 1.7-fold respectively. Such enhancement was not observed when combined irradiations were administered. UV exposure possessed a much higher influence on pro-MMP 9 secretion by dermal fibroblast enhancing enzyme levels by 2.5-, 6.5- and 5-fold for UVA, UVB and UVA+UVB, respectively.