Activation of Matrix Metalloproteinase‐2 by a Novel Oral Spirochetal Species Treponema lecithinolyticum

Background: Periodontal tissue destruction is a characteristic of periodontitis. This can be caused by either bacterial enzymes or host cell‐derived matrix metalloproteinases (MMPs). In order to elucidate the etiologic role of oral spirochetes, we investigated the effects of Treponema lecithinolyticum, a novel saccharolytic species, on MMP‐2 activation. Methods: Gingival fibroblasts (GFs) and periodontal ligament (PDL) cells obtained from healthy human subjects were cultured to confluence in α‐minimal essential medium (α‐MEM) supplemented with 10% fetal bovine serum. After serum starvation for a day, the cultures were treated with whole cell sonicates, heat‐denatured whole cell sonicates, outer membrane fraction (OMF) or formaldehyde‐fixed cells of T. lecithinolyticum. Culture supernatants were collected after incubation for 24 to 48 hours and analyzed for MMP‐2 activation by gelatin zymography. Collagenolytic activity was quantitatively measured using human [3H] type IV collagen as a substrate. Results: Treatment of GFs and PDL cells with whole cell sonicates, formaldehyde‐fixed whole cells, or the OMF of T. lecithinolyticum resulted in the production of MMP‐2 partly in the fully active form with a molecular mass of 62 kDa, whereas nontreated control cultures and cultures treated with a heat‐denatured fraction did not show the active form. Cultures exposed to T. lecithinolyticum had higher collagenolytic activity than non‐treated cultures. Conclusions: Our results demonstrate that T. lecithinolyticum, possibly mediated by proteinaceous cell surface‐associated components, may participate in extracellular matrix degradation by activation of MMP‐2 during periodontal inflammation. J Periodontol 2001;72:1594‐1600.