Activation of matrix metalloproteinase-2 by a novel oral spirochetal species Treponema lecithinolyticum

Background: Periodontal tissue destruction is a characteristic of periodont itis. This can be caused by either bacterial enzymes or host cell-derived m atrix metalloproteinases (MMPs). In order to elucidate the etiologic role o f oral spirochetes, we investigated the effects of Treponema lecithinolytic um, a novel saccharolytic species, on MMP-2 activation. Methods: Gingival fibroblasts (GFs) and periodontal ligament (PDL) cells ob tained from healthy human subjects were cultured to confluence in a-minimal essential medium (alpha -MEM) supplemented with 10% fetal bovine serum. Af ter serum starvation for a day, the cultures were treated with whole cell s onicates, heat-denatured whole cell sonicates, outer membrane fraction (OMF ) or formaldehyde-fixed cells of T lecithinolyticum. Culture supernatants w ere collected after incubation for 24 to 48 hours and analyzed for MMP-2 ac tivation by gelatin zymography. Collagenolytic activity was quantitatively measured using human [H-3] type IV collagen as a substrate. Results: Treatment of GFs and PDL cells with whole cell sonicates, formalde hyde-fixed whole cells, or the OMF of T lecithinolyticum resulted in the pr oduction 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 hea t-denatured fraction did not show the active form. Cultures exposed to T le cithinolyticum had higher collagenolytic activity than non-treated cultures . Conclusions: Our results demonstrate that T lecithinolyticum, possibly medi ated by proteinaceous cell surface-associated components, may participate i n extracellular matrix degradation by activation of MMP-2 during periodonta l inflammation.