α-macroglobulin-like plasma inactivator for Vibrio vulnificus metalloprotease

The metalloprotease produced by Vibrio vulnificus (VVP) is known to be quickly inactivated by plasma proteins which belong to the class of α-macroglobulins in vitro at a molar ratio of 1 : 1. But the in vivo potential of the inactivators has not been studied. Macroal-bumin (MA), a member of α-macroglobulins in Guinea pig plasma, was found to inactivate WP by means of physical entrapment in vitro. In vivo actions of VVP, permeability-enhancing and hemorrhagic actions, were greatly augmented by simultaneous injection of the antibody against MA, which had no effect on in vitro proteolytic action toward azocasein. The interstitial-tissue space in the normal Guinea pig skin contains a negligible amount of MA. However, sufficient MA was present in the extravascular fluid collected after the intradermal injection of VVP. Besides, in the extravascular fluid, VVP formed a complex with MA and no inactivator other than MA was found. These results indicate that plasma MA leaked from the vascular system owing to the permeability-enhancing and hemorrhagic actions of VVP, resulting in inactivation of VVP in situ.