INFLUENCE OF SUCCESSIVE AND COMBINED ULTRAVIOLET-A AND ULTRAVIOLET-B IRRADIATIONS ON MATRIX METALLOELASTASES PRODUCED BY HUMAN DERMAL FIBROBLASTS IN CULTURE

To study the cumulative influence of UV irradiations on skin matrix al terations, human skin fibroblasts were irradiated successively three-f old, at 24 h intervals, with UVA (3 x 5J/cm(2)), UVB (3 x 8mJ/cm(2)), UVA plus UVB (3 x 5J/cm(2) and 3 x 8mJ/cm(2)) and the levels of 92 kDa gelatinase (pro-MMP9), 72 kDa gelatinase (pro-MMP2) and plasma-membra ne elastase type protease were determined, following subsequent 24-h c ulture in 10% serum-containing medium. UV irradiations had only minor influence (1.4-fold increase fbr UVB) on secreted levels of pro-MMP, a nd 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 MMP2 production: 2.5- and 1.7-fold respectively. S uch enhancement was not observed when combined irradiations were admin istered. UV exposure possessed a much higher influence on pro-MMP, sec retion by dermal fibroblast enhancing enzyme levels by 2.5-, 6.5- and 5-fold for UVA, UVB and UVA+UVB, respectively. (C) 1997 Academic Press Limited.