Trypsin-like protease activity of Porphyromonas gingivalis as a potential virulence factor in a murine lesion model

Porphyromonas gingivalis possesses a large number of enzymatic activities which might be important in the virulence of this putative periodontopathogen. The purpose of this study was to examine these enzymatic activities in vivo in a murine model to assess their role in soft tissue destruction. Whole cells of P. gingivalis strains whether grown on blood agar plates or in broth exhibited high levels of alkaline phosphatase (ALPase), a trypsin-like protease (TLPase), acid phosphatase (ACPase), N-acetyl beta-glucosaminidase (Na beta-Gase) enzymes and collagenolytic activities. P. gingivalis W50 treated with 2 mM Na-P-tosyl-L-lysine chloromethyl ketone (TLCK)/phenylmethylsulfonyl fluoride (PMSF) prior to subcutaneous infection of mice failed to induce a phlegmonous abscess and lethality characteristic of animals challenged with untreated P. gingivalis. Comparison of wild type P. gingivalis strain 3079.03 with its protease-deficient (TLPase-negative) mutant NG4B19 revealed the mutant to be avirulent (no lesion and no death) in this model. P. gingivalis BEI and SW5 mutants (parent W50), which partially lacked TLPase enzyme activity produced only localized lesions, and no death. Thus, the TLPase enzyme appears to be correlated with the lesion type (spreading or localized), lesion size, and death in this mouse abscess model. Therefore, the enzymatic activities of P. gingivalis and specifically the TLPase enzyme could play an important role in periodontal disease by enhancing bacterial spread and degrading gingival tissues.