title: Purine nucleoside phosphorylase activity and expression are upregulated in sites affected by periodontal disease.
abstract: OBJECTIVE
  Purine nucleoside phosphorylase (PNP) is an enzyme that catalyzes the reversible phosphorolysis of purine nucleosides, playing a key role in the purine salvage pathway. Activated T cells seem to rely heavily on PNP to remain functionally active and are particularly sensitive to PNP deficiency. The role of PNP in periodontal tissues has not been characterized thus far. The aim of this study therefore was to assess the activity and expression of PNP in the gingival tissues of periodontitis patients.
  
  
  METHODS
  Ten patients consecutively admitted for treatment had their periodontal clinical variables recorded and their gingival crevicular fluid collected. After periodontal treatment the patients were seen once a month for plaque and bleeding control, and had their periodontal variables recorded and gingival crevicular fluid collected at 90 and 180 d. Purine nucleoside phosphorylase-specific activity was assessed using a spectrophotometer through the addition of the PNP substrate analog 2-amino-6mercapto-7-methyl purine riboside to the gingival crevicular fluid. In parallel, PNP expression was assessed by immunohistochemistry and real-time PCR in gingival biopsies and cell culture.
  
  
  RESULTS
  Purine nucleoside phosphorylase activity was higher in the gingival crevicular fluid of periodontally diseased sites, which was positively correlated with improvements of the clinical variables. Treatment of periodontal disease induced a striking decrease of PNP activity in periodontally diseased sites. Expression of PNP was more pronounced in mononuclear cells and endothelial cells of the gingiva, and the mRNA levels were 5.7-fold higher in inflamed tissues compared with control samples.
  
  
  CONCLUSIONS
  Purine nucleoside phosphorylase activity and expression are upregulated in periodontally diseased sites and can be detected in the gingival crevicular fluid.
authors.affiliation: Division of Periodontology, School of Dental Medicine, Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS, Brasil. eraldo.junior@pucrs.br
authors.forename: E L
authors.initials: EL
authors.lastname: Batista
authors.forename: C
authors.initials: C
authors.lastname: Deves
authors.forename: L
authors.initials: L
authors.lastname: Ayub
authors.forename: R G
authors.initials: RG
authors.lastname: da Silva
authors.forename: L C C
authors.initials: LC
authors.lastname: Filho
authors.forename: L A
authors.initials: LA
authors.lastname: Basso
authors.forename: D S
authors.initials: DS
authors.lastname: Santos
mesh_terms: D000328:Adult; D000368:Aged; D010520:Aggressive Periodontitis / Q000201:enzymology* / Q000628:therapy; D015496:CD4-Positive T-Lymphocytes / Q000201:enzymology; D055113:Chronic Periodontitis / Q000201:enzymology* / Q000628:therapy; D015971:Gene Expression Regulation, Enzymologic; D005881:Gingiva / Q000201:enzymology; D005883:Gingival Crevicular Fluid / Q000201:enzymology*; D006801:Humans; D007156:Immunologic Memory; D008875:Middle Aged; D016011:Normal Distribution; D011683:Purine-Nucleoside Phosphorylase / Q000235:genetics* / Q000378:metabolism*; D018709:Statistics, Nonparametric; D015854:Up-Regulation
chemical_list: D011683:Purine-Nucleoside Phosphorylase