Characterization of hemorrhagic dermatosis induced by metalloprotease of pathogenic vibrios.

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Vibrio vulnificus is an opportunistic pathogen causing wound infections and septicemia, characterized by hemorrhagic and edematous damage to the skin. This human pathogen secretes a metalloprotease (V. vulnificus protease {VVP}) as an important virulence determinant. When several bacterial metalloproteases including VVP were injected intradermally into dorsal skin, VVP showed the greatest hemorrhagic activity. The level of the in vivo proteolytic activity of the bacterial metalloprotease was significantly correlated with that of the in vitro hemorrhagic activity for the reconstituted basement membrane gel. Of two major basement membrane components (laminin and type IV collagen), only type IV collagen was easily digested by VVP. Histopathological observations of skin injected with VVP indicated the severe damages in deep region of dermis and subcutaneous tissue. In these portion, hemorrhage and swelling of lipocyte (fat cell or adipose cell) were observed near the blood vessels in the dermis and subcutaneous tissues. The capillary vessels in hemorrhagic region were destroyed or congested with blood. Histopathological observations of the hemorrhagic actions induced by VVP indicated the another possibilities of the degradation of capillary vessels by the necrosis of endothelial cells.