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Updated: Jul 14, 2026
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Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells
Published on: December 17, 2015
Biphasic effect of gingipains from Porphyromonas gingivalis on the human complement system
Katarzyna Popadiak1, Jan Potempa, Kristian Riesbeck
1Lund University, Department of Laboratory Medicine, Section of Medical Protein Chemistry, University Hospital Malmö, Malmö, Sweden.
Journal of Immunology (Baltimore, Md. : 1950)
|May 22, 2007
Summary
Porphyromonas gingivalis proteases, called gingipains, degrade human complement, reducing its bacteria-killing ability. Mutants lacking gingipains show increased resistance to complement, highlighting gingipains' role in periodontitis pathogenesis.
Area of Science:
- Microbiology
- Immunology
- Oral Health
Background:
- Periodontitis is an inflammatory oral disease linked to Porphyromonas gingivalis.
- P. gingivalis exhibits resistance to human complement, a key immune defense.
- Gingipains are proteases produced by P. gingivalis.
Purpose of the Study:
- To investigate the mechanism by which P. gingivalis proteases (gingipains) affect the bactericidal activity of human complement.
- To elucidate the role of gingipains in P. gingivalis resistance to complement-mediated killing.
Main Methods:
- Incubation of human serum with purified gingipains and P. gingivalis wild-type and mutant strains.
- Assessment of serum bactericidal activity post-incubation.
- Analysis of complement component degradation and C1 complex activation by gingipains.
Main Results:
- Gingipains significantly reduced the bactericidal activity of human serum.
- P. gingivalis mutants lacking gingipains (especially HRgpA) showed retained serum bactericidal activity.
- Arginine-specific gingipains (HRgpA, RgpB) were more effective than lysine-specific gingipain (Kgp) in degrading complement components.
- Gingipains activated the C1 complex, leading to C1q deposition on bacteria and surfaces.
Conclusions:
- Gingipains contribute to P. gingivalis resistance against the human complement system.
- Early complement activation by gingipains may promote local inflammation and bacterial colonization.
- High protease concentrations later in infection degrade complement, conferring bacterial resistance.
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