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Published on: March 18, 2010
Interpain A, a cysteine proteinase from Prevotella intermedia, inhibits complement by degrading complement factor C3
Michal Potempa1, Jan Potempa, Tomasz Kantyka
1Lund University, Department of Laboratory Medicine, Section of Medical Protein Chemistry, University Hospital Malmö, Malmö, Sweden.
Plos Pathogens
|February 28, 2009
Summary
Prevotella intermedia, a cause of periodontitis, uses interpain A to resist the human complement system. This cysteine protease degrades complement factor C3, aiding bacterial survival and potentially worsening gum disease.
Area of Science:
- Oral microbiology
- Immunology
- Biochemistry
Background:
- Periodontitis is a severe gum disease linked to Prevotella intermedia.
- Prevotella intermedia strains often resist the human complement system, a key immune defense.
- Gingival crevicular fluid contains high concentrations of complement proteins.
Purpose of the Study:
- To investigate the role of Prevotella intermedia's cysteine protease, interpain A, in evading the human complement system.
- To determine if interpain A is a virulence factor in periodontitis.
Main Methods:
- Incubation of human serum with recombinant interpain A.
- Comparing serum resistance of P. intermedia strains with and without interpain A expression (Western blotting).
- Assessing the effect of cysteine protease inhibitor E64 on bacterial killing.
- Analyzing complement component C3 degradation and C1 complex activation.
Main Results:
- Recombinant interpain A significantly reduced serum's bactericidal activity.
- Interpain A-expressing P. intermedia strains showed increased serum resistance.
- Inhibition of interpain A enhanced bacterial killing by serum.
- Interpain A degrades C3, inhibiting all three complement pathways.
- Interpain A acts synergistically with P. gingivalis gingipains and activates the C1 complex.
Conclusions:
- Interpain A is a significant virulence factor for Prevotella intermedia in periodontitis.
- Interpain A's ability to degrade complement components contributes to P. intermedia's survival.
- Interpain A's interaction with the complement system may play a role in early infection stages.
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