Laminin 5 and Gelatinase Alterations in Mouse Skin Following Sulfur Mustard (SM) Exposure

Epidermolysis bullosa (EB), a genetic skin disease characterized by skin blistering, may be caused by mutations in any of a variety of genes that encode proteins required for maintaining the structural integrity of skin. Three of these genes, laminin-α3, laminin-β3, and laminin-γ2 produce separate polypeptides that together form the basement membrane protein, laminin 5. Disruption of laminin 5 protein causes skin blisters that may be further enhanced by the actions of matrix metalloproteinases (MMPs). The chemical warfare agent, bis(2-chloroethyl)sulfide (sulfur mustard, SM), penetrates the skin rapidly and within several hours causes skin blistering similar to EB. After exposure to liquid SM, mouse ear skin was examined for upregulation of expression of the laminin 5 polypeptide chains and MMPs 2 and 9 (gelatinase A and B, respectively). Punch biopsies of mouse ear skin were taken at 6, 12, 24, and 72 hours after SM exposure. They were examined by histology, real-time PCR and gelatinase activity assays. SM caused a time-dependent increase in skin weight and damage relative to vehicle controls. Increased mRNA levels for MMP-9, and laminin-γ2, were noted after SM exposure whereas MMP-2, laminin-α3, and laminin-β3 mRNA levels remained the same. There was a time-related increase in overall gelatinase activity observable 6 hours after SM exposure and which persisted throughout the study. Pretreatment with the MMP inhibitor, ilomastat, appeared to have no effect on the observations. Taken together, these observations may form the basis for an in vivo assay to test the efficacy of pharmacological countermeasures useful in preventing or alleviated SM induced skin damage. *This work is supported by the U.S. Army Medical Research and Materiel Command under Contract No. DAMD17-02-C-0091.