The gingipains from Porphyromonas gingivalis do not directly induce osteoclast differentiation in primary mouse bone marrow cultures.
OBJECTIVE
Porphyromonas gingivalis is a major aetiological agent in the development of periodontitis, the major clinical hallmark of which is bone resorption. The cysteine proteases (gingipains) produced by P. gingivalis have a critical role in the pathogenesis of the disease, and previous studies on whole bacteria have implicated these enzymes in osteoclastogenesis, a process which serves to upregulate bone resorption. The effects of the gingipains from P. gingivalis on osteoclast differentiation were investigated here to determine whether the enzymes directly contribute to osteoclastogenesis and thus to bone resorption.


METHODS
The effects of the gingipains on osteoclast differentiation were investigated in primary mouse bone marrow cultures. The cultures harvested from C57BL6/J mice were incubated in the presence of parathyroid hormone, a known osteoclastogenic factor, or active/inactivated forms of three gingipains. Osteoclast differentiation was quantified by counting the number of multinucleated cells positive for tartrate-resistant acid phosphatase, an enzyme marker for these cells.


RESULTS
After 10 days of culture, the gingipains, either active or inactive, failed to stimulate osteoclast differentiation in comparison to the parathyroid hormone.


CONCLUSIONS
The data presented here demonstrate that the gingipains do not induce osteoclast differentiation in this system, indicating that the bacterium uses other mechanisms to induce bone loss.
Fitzpatrick
R E
RE
Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
Campbell
P D
PD
Sivagurunathan
S
S
Pagel
C N
CN
Potempa
J
J
Mackie
E J
EJ
Pike
R N
RN
D000135:Acid Phosphatase / Q000032:analysis; D018829:Adhesins, Bacterial / Q000494:pharmacology*; D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects*; D001862:Bone Resorption / Q000473:pathology; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000494:pharmacology*; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D010010:Osteoclasts / Q000187:drug effects*; D010281:Parathyroid Hormone / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D016966:Porphyromonas gingivalis / Q000502:physiology*; D000071681:Tartrate-Resistant Acid Phosphatase
D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins; D007527:Isoenzymes; D010281:Parathyroid Hormone; D010446:Peptide Fragments; C102836:parathyroid hormone (1-31)amide, human; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D003546:Cysteine Endopeptidases