CELLULAR SOURCE, ACTIVATION AND INHIBITION OF DENTAL PLAQUE COLLAGENASE

Dental plaque is the major aetiological factor in periodontal diseases and contains several proteolytic enzymes. The origin of these protein ases is, however, poorly studied. This study was undertaken to charact erize collagenase present in dental plaque of adult periodontitis pati ents. Vertebrate-type rather than bacterial-derived collagenase activi ty was detected in extracts of both supra- and subgingival dental plaq ue extracts of adult periodontitis patients. Dental plaque collagenase was found to exist predominantly in autoactive form. Dental plaque co llagenase from periodontally healthy individuals existed in latent for m. Latent dental plaque collagenase from periodontitis lesions could b e activated by a 95 kD chymotrypsin-like proteinase from Treponema den ticola and human leukocyte cathepsin G but not by human plasmin. Incub ation of purified latent leukocyte collagenase with whole cells of Fus obacterium nucleatum, Eubacterium saburreum, Prevotella buccae and Por phyromonas gingivalis, however, did not result to the activation of th e enzyme. Doxycycline in vitro inhibited dental plaque collagenase wit h an IC50-value of 20 mu M. Dental plaque collagenase degraded more ef ficiently type I and II collagens than type III collagen. Western-blot analysis with specific anti-human neutrophil collagenase-antibody rev ealed that both in supra-and subgingival dental plaque extracts dental plaque collagenase had undergone proteolytic conversion from an 80 kD preform to a 58 kD active form which is associated with catalytic aut oactivity as measured by functional collagenase assay. This reflects p roteolytic activation of leukocyte collagenase in dental plaque probab ly by other proteases derived from potent periodontopathogenic bacteri a such as T. denticola or other PMN proteases such as cathepsin G. Mul tiple different molecular weight gelatinases (20-200 kD) including fra gmented low molecular weight human neutrophil 92 kD gelatinase species were detected in both supra- and subgingival dental plaque extracts. Leukocyte collagenase, previously found to be the main type of collage nase present in adult periodontitis gingiva, gingiva crevicular fluid and saliva, is also the predominant type of collagenase in the plaque of periodontitis patients. Fragmented but catalytically active neutrop hil gelatinase species are also present in dental plaque. The dental p laque has potential to serve as a reservoir and site of activation of neutrophil (PMN)-derived matrix metalloproteinases in the periodontal inflammation.