title: Matrix metalloproteinase-13 is highly expressed in destructive periodontal disease activity.
abstract: BACKGROUND
  Matrix metalloproteinases (MMPs) participate in extracellular matrix degradation in physiological and pathological conditions. The available evidence suggests that MMP-13 plays a significant role in both the initiation and progress of bone resorption. The aim of our study was to identify the presence of MMP-13 in adult patients with untreated chronic periodontitis. We also determined the activity of MMP-13 present in lesions undergoing episodic attachment loss in gingival crevicular fluid (GCF) samples.
  
  
  METHODS
  After monitoring at 2 and 4 months, 21 patients showed destructive periodontitis (periodontally affected sites presenting at least two sites with > or =2 mm clinical attachment loss), and GCF samples were collected both from active and inactive sites (21 GCF samples, each). GCF was collected during a 30-second interval using a paper strip, and an immunofluorescence assay was performed to determine the basal activity of MMP-13 and the relationship between 4-aminophenylmercuric acetate (APMA)-activated total MMP-13 and basal MMP-13 activity. Gingival tissues from five patients were fixed in formalin and MMP-13 expression was demonstrated using immunohistochemistry and in situ hybridization. MMP-13 molecular forms were examined by Western immunoblotting with monoclonal antibodies.
  
  
  RESULTS
  MMP-13 was found in 100% of GCF samples from patients with chronic periodontitis. Active sites, associated with tissue destruction, had significantly higher proportions of active MMP-13 and MMP-13 activity levels than their inactive counterparts (1.49 versus 1.17 ng fluorescent product, respectively; P <0.05). Western blot, immunohistochemical staining, and in situ hybridization confirmed the presence of MMP-13 in periodontal disease, with observable differences between periodontitis and healthy subjects. MMP-13 immunoreactivities were seen mainly as 55 and 48 kDa, corresponding to partially and fully activated forms, respectively, and a smaller proportion of 60-kDa proenzyme form.
  
  
  CONCLUSIONS
  MMP-13 activity in GCF samples was significantly increased in active sites from progressive periodontal disease, supporting its role in the alveolar bone loss developed in this disease.
authors.affiliation: Periodontal Biology Laboratory, Dentistry School, University of Chile, Santiago, Chile.
authors.forename: Marcela
authors.initials: M
authors.lastname: Hernandez
authors.forename: Maria Antonieta
authors.initials: MA
authors.lastname: Valenzuela
authors.forename: Carlos
authors.initials: C
authors.lastname: Lopez-Otin
authors.forename: Jesús
authors.initials: J
authors.lastname: Alvarez
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Lopez
authors.forename: Rolando
authors.initials: R
authors.lastname: Vernal
authors.forename: Jorge
authors.initials: J
authors.lastname: Gamonal
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000201:enzymology*; D015153:Blotting, Western; D016022:Case-Control Studies; D002908:Chronic Disease; D004789:Enzyme Activation; D005260:Female; D005883:Gingival Crevicular Fluid / Q000201:enzymology; D006801:Humans; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D008137:Longitudinal Studies; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000096:biosynthesis* / Q000502:physiology*; D008875:Middle Aged; D017622:Periodontal Attachment Loss / Q000201:enzymology; D010512:Periodontal Index; D010518:Periodontitis / Q000201:enzymology*
chemical_list: D053509:Matrix Metalloproteinase 13