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Alpha-macroglobulin-like plasma inactivator for Vibrio vulnificus metalloprotease
Abstract:
The metalloprotease produced by Vibrio vulnificus (VVP) is known to be quickly inactivated by plasma proteins which belong to the class of alpha-macroglobulins in vitro at a molar ratio of 1:1. But the in vivo potential of the inactivators has not been studied. Macroalbumin (MA), a member of alpha-macroglobulins in guinea pig plasma, was found to inactivate VVP 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.
Insights
Vibrio vulnificus metalloprotease (VVP) is inactivated by macroalbumin (MA) in guinea pigs. VVP
Area of Science:
- Microbiology
- Biochemistry
- Immunology
Background:
- Vibrio vulnificus metalloprotease (VVP) is inactivated by plasma proteins in vitro.
- The in vivo inactivation potential of these plasma proteins remains unstudied.
- Macroalbumin (MA), an alpha-macroglobulin in guinea pig plasma, inactivates VVP via physical entrapment in vitro.
Purpose of the Study:
- To investigate the in vivo inactivation of VVP by MA.
- To elucidate the role of MA in modulating VVP's pathogenic effects in vivo.
Main Methods:
- In vivo studies using guinea pigs injected with VVP and anti-MA antibody.
- Assessment of VVP's permeability-enhancing and hemorrhagic actions.
- Analysis of MA presence and VVP-MA complex formation in extravascular fluid.
- In vitro proteolytic activity assay using azocasein.
Main Results:
- In vivo VVP actions were significantly enhanced by anti-MA antibody, indicating MA's inhibitory role.
- MA was found in the extravascular fluid after VVP injection, forming a complex with VVP.
- No other VVP inactivators were detected in the extravascular fluid.
- Anti-MA antibody did not affect VVP's in vitro proteolytic activity on azocasein.
Conclusions:
- Plasma MA leaks into tissues due to VVP's actions, leading to VVP inactivation in situ.
- MA plays a crucial role in limiting VVP's pathogenicity in vivo.
- This study highlights the importance of alpha-macroglobulins in host defense against bacterial proteases.