RELEASE AND ACTIVATION OF HUMAN NEUTROPHIL MATRIX METALLO-PROTEINASESAND SERINE-PROTEINASES DURING PHAGOCYTOSIS OF FUSOBACTERIUM-NUCLEATUM, PORPHYROMONAS-GINGIVALIS AND TREPONEMA-DENTICOLA

The phagocytic ingestion of reference strains and clinical isolates of Fusobacterium nucleatum, Porphyromonas gingivalis, and Treponema dent icola by polymorphonuclear leukocytes (PMNs) and the concomitant relea se of PMN granule proteinases were studied by specific functional and immunological assays. PMNs were incubated with the microorganisms anae robically at 37 degrees C for indicated time periods. The suspensions and pellets were used for phagocytic ingestion assay and electron micr oscopic study, respectively. The supernatants were used for the measur ements of the amounts and activities of the released PMN enzymes inclu ding PMN gelatinase (MMP-9), collagenase (MMP-8), serine proteases (el astase and cathepsin G), and lactate dehydrogenase (LDH). Both fluores cence microscopy and transmission electron microscopy showed that F. n ucleatum, P. gingivalis and T. denticola were ingested by the PMNs in comparable numbers. However, measurements of the enzymes released from the triggered PMNs revealed major differences among the three species . High amount of elastase was released from the PMNs triggered by F. n ucleatum, but not by P. gingivalis or T. denticola. The treatment of P MNs with P. gingivalis whole cells resulted in the release of gelatina se partly in the 82 kD active form, suggesting proteolytic activation of the degranulated 92 kD proMMP-9. The 82 kD active form of gelatinas e was not detected upon triggering the PMNs with F. nucleatum and T. d enticola. The PMN-bacteria interaction did not result in release of LD H from triggered PMNs indicating the proteinase release was not due to the PMN cell death. The results show that the susceptibilities of the 3 potentially periodonto-pathogenic microorganisms, F. nucleatum, P. gingivalis and T. denticola to phagocytic ingestion are not directly r elated to the amounts and activities of PMN enzymes released during th e bacteria-PMN interactions. As PMN degranulation is considered as one of the major pathogenic mechanisms in periodontitis, the observed dif ferences among the microorganisms may be important virulence character istics of these species.