TheTreponema denticolaChymotrypsin-Like Protease Dentilisin Induces Matrix Metalloproteinase-2-Dependent Fibronectin Fragmentation in Periodontal Ligament Cells
ABSTRACTPeriodontal disease is a bacterially mediated chronic inflammatory disease that results in destruction of the periodontal ligament (PDL) and alveolar bone that surround and support the dentition. While their precise roles are not well understood, periodontal pathogens, includingTreponema denticola, are believed to initiate the destructive inflammatory responses and dysregulation of tissue homeostasis that characterize the disease. These responses are believed to result from both proinflammatory effects of acylated bacterial membrane components (lipopolysaccharides and lipoproteins) and degradative effects of secreted bacterial proteases. Host-derived matrix metalloproteinases (MMPs) are key enzymes both in tissue homeostasis and tissue destruction. MMP expression is modulated in part by specific proteolytic fragments of fibronectin (FN), which are associated with periodontal disease. FN is a predominant extracellular matrix component in the periodontium. We examined the ability ofTreponema denticolaand its acylated outer membrane PrtP protease complex to induce both activation of MMP-2 and generation of FN fragments in human PDL cell culture supernatants.T. denticolaparent and isogenic mutant strains, as well as MMP-2 small interfering RNA and specific inhibitors of MMP-2 and PrtP activity, were used to examine protein expression, gelatinolytic activity, and FN fragmentation in culture supernatants.T. denticolaand its purified protease induced both MMP-2 activation and FN fragmentation. Here, we demonstrate that PrtP proteolytic activity induces the activation of MMP-2 and that active MMP-2 is required for FN fragmentation. These results suggest a specific mechanism by which theT. denticolaprotease may disrupt homeostatic processes required for the maintenance of periodontal health.