Porphyromonas gingivalis promotes monocyte migration by activating MMP-9.
OBJECTIVE
The migration of monocytes into the local environment is crucial for their maturation into macrophages or osteoclasts in the pathogenesis of periodontal disease. The objective of this study was to investigate the role and mechanisms mediated by Porphyromonas gingivalis in promoting the migration of monocytes by regulating MMP-9 and TIMP-1 expression.


METHODS
Human THP1 monocytes were treated with culture supernatant derived from P. gingivalis (ATCC 33277) for 24 h. Zymography, western blot analysis and quantitative PCRs were performed to analyse protein and mRNA levels of MMP-9. Protein and mRNA levels of TIMP-1 from monocytes treated with or without P. gingivalis were determined as well. Transwell migration assay was carried out to analyse the effect of P. gingivalis on the migration of human peripheral blood CD14-positive monocytes. An MMP inhibitor (GM6001) and a proteinase inhibitor (leupeptin) were used to determine the role of MMP-9 in P. gingivalis supernatant- and lipopolysaccharide-induced monocyte migration.


RESULTS
In zymography and western blot, an 82 kDa band of active MMP-9 emerged in P. gingivalis-treated monocyte culture media in a dose-dependent manner, in addition to the MMP-9 proenzyme (92 kDa) band expressed in control cell culture media. P. gingivalis supernatant increased both the protein and the mRNA levels of MMP-9 and TIMP-1. P. gingivalis supernatant, but not its lipopolysaccharide, increased the migratory ability of CD14-positive monocytes. The increased migratory ability of P. gingivalis-treated monocytes was partly inhibited by leupeptin (200 μg/mL) and completely antagonized by the MMP inhibitor GM6001 (100 nm). Lipopolysaccharide of P. gingivalis increased protein and mRNA levels of MMP-9 in monocytes, but had no effect on the migratory ability or MMP-9 activation.


CONCLUSIONS
P. gingivalis supernatant increased the migratory ability of monocytes, in part, by increasing activation and expression of MMP-9.
Department of Pediatric Dentistry and Orthodontics, Medical University of South Carolina, Charleston, SC 29401, USA. zhouj@musc.edu
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Zhou
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Zhang
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J
Chao
D002403:Cathepsins / Q000037:antagonists & inhibitors; D018929:Cell Culture Techniques; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000502:physiology; D017077:Culture Media, Conditioned; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000378:metabolism; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000032:analysis; D008070:Lipopolysaccharides / Q000494:pharmacology; D020780:Matrix Metalloproteinase 9 / Q000187:drug effects / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D009000:Monocytes / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D016966:Porphyromonas gingivalis / Q000502:physiology*; D011480:Protease Inhibitors / Q000494:pharmacology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism
D017077:Culture Media, Conditioned; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D004792:Enzyme Precursors; D007976:Leupeptins; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D061965:Matrix Metalloproteinase Inhibitors; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D011480:Protease Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D002403:Cathepsins; D020780:Matrix Metalloproteinase 9; C032854:leupeptin