ABSTRACT
Infection with Porphyromonas gingivalis is strongly associated with adult periodontitis, and proteinases are considered to be important virulent factors of the bacterium. In order to investigate the function of proteinases in disease development we examined vesicles, a biological carrier of these enzymes, for the generation of vascular permeability enhancement (VPE) activity, believed to correlate with the exudation of gingival crevicular fluid. The vesicles generated VPE activity from human plasma in a dose-dependent manner which could be inhibited 90% by antipain, a specific inhibitor of the Arg-specific cysteine proteinases (Arg-gingipains [RGPs] from P. gingivalis. Incubation of vesicles with high-molecular-weight-kininogen (HMWK)-deficient plasma did not result in VPE activity. On this basis, RGPs associated with vesicles were assumed to be responsible for most of the VPE activity generation via plasma prekallikrein activation and subsequent bradykinin production. The secondary pathway for VPE activity production was dependent on the direct release of bradykinin from HMWK by the concerted action of RGP and a Lys-specific cysteine proteinase (Lys-gingipain [KGP]), also associated with vesicles. These results indicate that RGP and KGP are biologically important VPE factors acting either via prekallikrein activation (RGP) and/or HMWK cleavage (RGP and KGP) to release BK and, thereby, contributing to the production of gingival crevicular fluid at periodontal sites infected with P. gingivalis.
