PAI-2/SerpinB2 inhibits proteolytic activity in a P. gingivalis-dominated multispecies bacterial consortium.
OBJECTIVE
The aim of this study was to investigate the ability of the serine protease inhibitor plasminogen activator inhibitor type 2 (PAI-2/Serpin B2) to inhibit proteases produced by a multispecies bacterial consortium in vitro.


BACKGROUND
Gingival and periodontal inflammation is associated with an increased flow of protein-rich gingival fluid. This nutritional change in the microenvironment favors bacteria with a proteolytic phenotype, triggering inflammation and associated tissue breakdown. PAI-2 is produced by macrophages and keratinocytes and is present in very high concentrations in gingival crevicular fluid; the highest level in the body.


METHODS
A multispecies bacterial consortium comprising nine bacterial strains, resembling the conditions in a periodontal pocket, was grown planktonically and as a biofilm. After seven days PAI-2 was added to the consortium and the proteolytic activity was assayed with fluorogenic protease substrates; FITC-labeled casein to detect global protease activity, fluorescent H-Gly-Pro-AMC for serine protease activity and fluorescent BIKKAM-10 for Porphyromonas gingivalis-associated protease activity. Protease activity associated with biofilm cells was examined by confocal scanning laser microscopy.


RESULTS
PAI-2 inhibited proteolytic activity of the bacterial consortium, as seen by decreased fluorescence of all substrates. PAI-2 specifically inhibited P. gingivalis proteolytic activity.


CONCLUSIONS
To our knowledge, this is the first time that PAI-2 has been shown to inhibit bacterial proteases. Given the high concentration of PAI-2 in the gingival region, our results indicate that PAI-2 might play a role for the integrity of the epithelial barrier.
Department of Oral Biology, Faculty of Odontology, Malmö University College, Malmö, Sweden.
Jessica
J
Neilands
Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, Free University and University of Amsterdam, Amsterdam, The Netherlands.
Floris J
FJ
Bikker
Department of Oral Biology, Faculty of Odontology, Malmö University College, Malmö, Sweden. Electronic address: Bertil.Kinnby@mah.se.
Bertil
B
Kinnby
D058491:Bacterial Load; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005881:Gingiva / Q000382:microbiology; D005883:Gingival Crevicular Fluid / Q000737:chemistry / Q000201:enzymology; D005891:Gingivitis / Q000201:enzymology / Q000378:metabolism / Q000382:microbiology; D018928:Immunity, Mucosal; D059013:Microbial Consortia / Q000187:drug effects; D010447:Peptide Hydrolases / Q000187:drug effects* / Q000378:metabolism; D010514:Periodontal Pocket / Q000201:enzymology / Q000378:metabolism / Q000382:microbiology; D017396:Plasminogen Activator Inhibitor 2 / Q000494:pharmacology*; D016966:Porphyromonas gingivalis / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D011480:Protease Inhibitors / Q000494:pharmacology*
D001426:Bacterial Proteins; D017396:Plasminogen Activator Inhibitor 2; D011480:Protease Inhibitors; D010447:Peptide Hydrolases
Host-pathogen interaction; Mucosal immunology; PAI-2; Plasminogen activator inhibitor type 2; Protease inhibitor; SerpinB2