title: Matrix metalloproteinase-2 may be involved with increased bone loss associated with experimental periodontitis and smoking: a study in rats.
abstract: BACKGROUND
  Smoking has been associated with periodontitis severity and is considered a risk factor for its development. It has been reported that matrix metalloproteinase (MMP) produced by host cells plays a major role in periodontal tissue destruction. Thus, the present study tested, in rats, the hypothesis that local increased levels of MMP-2 would be associated with the enhanced periodontitis-related bone loss after intermittent cigarette smoke inhalation (CSI).
  
  
  METHODS
  Twenty-seven adult male Wistar rats were used. A ligature was placed around one of the mandibular first molars of each animal and they were randomly assigned to the following control (N = 13) or CSI (N = 14) group. Sixty days later, the animals were sacrificed, the gingival tissues harvested, and the specimens processed for decalcified sections. Extracts from the gingival tissues were prepared and assayed for MMP-2 expression.
  
  
  RESULTS
  Intergroup comparisons (unligated sites) showed that CSI might directly affect alveolar bone (0.16 +/- 0.03 mm2 versus 0.24 +/- 0.09 mm2 for non-smokers and smokers, respectively; P = 0.001). Moreover, CSI significantly enhanced bone loss resulting from experimental periodontitis (0.64 +/- 0.36 mm2 versus 1.50 +/- 0.50 mm2 for non-smokers and smokers, respectively; P<0.05). In addition, zymography demonstrated that CSI also enhanced both MMP-2 levels and activity in the gingival tissues around ligated teeth.
  
  
  CONCLUSIONS
  Within the limits of the present investigation, it can be assumed that the effect of CSI on MMP-2 levels and activity may account for the increased periodontitis progression rate observed in smokers.
authors.affiliation: Department of Prosthodontics and Periodontics, Division of Periodontics, School of Dentistry at Piracicaba, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: João Batista
authors.initials: JB
authors.lastname: César Neto
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: de Souza
authors.forename: Deise
authors.initials: D
authors.lastname: Barbieri
authors.forename: Heitor
authors.initials: H
authors.lastname: Moreno
authors.forename: Enilson Antonio
authors.initials: EA
authors.lastname: Sallum
authors.forename: Francisco Humberto
authors.initials: FH
authors.lastname: Nociti
mesh_terms: D016301:Alveolar Bone Loss / Q000201:enzymology / Q000209:etiology*; D000818:Animals; D008026:Ligation; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D023421:Models, Animal; D010518:Periodontitis / Q000201:enzymology / Q000209:etiology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012907:Smoking / Q000009:adverse effects* / Q000378:metabolism
chemical_list: D020778:Matrix Metalloproteinase 2