Synthetic inhibitors of matrix metalloproteinases prevent sulfur mustard-induced epidermal-dermal separation in human skin pieces

Degradation of proteins of the basement membrane zone (BMZ) in the skin depends on the activity of proteolytic enzymes, particularly those belonging to the group of matrix metalloproteinases (MMPs). In the present study we have investigated the contribution of these enzymes to the epidermal-dermal separation in human skin pieces that had been exposed to saturated vapor of HD at 25 ºC. The release of MMP-1, MMP-2, MMP-3 and MMP-9 in the organ culture media by human skin pieces, that were either or not exposed to HD vapor, have been determined by using substrate zymography and ELISA. The results showed that secretion of MMP-1, -9 and -3 from control skin is inhibited after exposure to HD vapor, whereas release of the latent form of MMP-2 is somewhat enhanced by HD. The spatial and temporal distribution of the four MMPs and their naturally occurring inhibitors TIMP-1 and TIMP-2 in human skin pieces has been analyzed immunohistochemically. For each antigen staining is weak or absent in epidermis and dermis of control skin. Only minor changes in the expression of MMPs and TIMPs are observed between control skin and HDexposed skin at 6, 16, 24 or 48 h of organ culture. However, a strong proof for the involvement of MMPs in epidermal-dermal separation of HD-exposed skin has been obtained by the potent inhibition of microvesication in human skin pieces when a synthetic inhibitor of MMPs, i.e. either BB94 or BB3103, was added to the organ culture medium. These results implicate the involvement of MMPs in the pathogenesis of HD-induced vesication and suggest the use of synthetic MMP inhibitors as a novel therapeutic strategy against HDinduced vesication.