title: Evaluation of correlation of articular cartilage staining for DDR2 and proteoglycans with histological tissue damage and the results of radiographic assessment in patients with early stages of knee osteoarthritis.
abstract: OBJECTIVE
  To determine, if staining of articular cartilage for proteoglycans (natural element of healthy and functioning cartilage) and discoidin domain receptor 2 (DDR2) (a protein associated with articular cartilage degradation) is correlated with histological tissue damage or radiographic assessment score in patients with early stages of knee osteoarthritis (OA).
  
  
  METHODS
  40 patients, with early stage OA were enrolled, from whom the biopsies for histological and immunohistochemical studies were obtained from edge of the femoral condyle during the arthroscopy. Semi-quantitative computer based analysis was used to evaluate the proportion of staining in histological sections.
  
  
  RESULTS
  No correlation was shown between the proportion of tissue stained for DDR2 and histological score or the results of radiographic assessment of tibiofemoral (TF) joint. There was a negative correlation between the proportion of tissue stained for DDR2 and radiographic grade of patellofemoral (PF) OA (Spearman r=-0.34; 95% CI -0.60 to -0.02; P=0.03). No correlation was shown between the proportion of tissue stained for proteoglycans and histological score or the results of radiographic assessment of TF and PF joints. A negative correlation was found between proportion of tissue stained for DDR2 and proteoglycans. Spearman r=-0.43; 95% CI=-0.66 to -0.12; P=0.006.
  
  
  CONCLUSIONS
  Production of DDR2 in articular cartilage could be related to early stages of OA, as it is significantly correlated to decrease of staining for cartilage proteoglycans. The role of production of DDR2 in cartilage may be decreased in stages, where higher grades of OA are detected on the radiographs.
authors.affiliation: Department of Anatomy, University of Tartu Estonia.
authors.forename: Siim
authors.initials: S
authors.lastname: Suutre
authors.affiliation: Internal Medicine Clinic, Tartu University Hospital Estonia.
authors.forename: Irina
authors.initials: I
authors.lastname: Kerna
authors.affiliation: Radiology Clinic, Tartu University Hospital Estonia.
authors.forename: Mare
authors.initials: M
authors.lastname: Lintrop
authors.affiliation: Pathology Service, Tartu University Hospital Estonia.
authors.forename: Hannes
authors.initials: H
authors.lastname: Tamm
authors.affiliation: Department of Anatomy, University of Tartu Estonia.
authors.forename: Marina
authors.initials: M
authors.lastname: Aunapuu
authors.affiliation: Department of Anatomy, University of Tartu Estonia.
authors.forename: Andres
authors.initials: A
authors.lastname: Arend
authors.affiliation: Internal Medicine Clinic, Tartu University Hospital Estonia.
authors.forename: Agu
authors.initials: A
authors.lastname: Tamm
mesh_terms: D000328:Adult; D001182:Arthroscopy; D015415:Biomarkers / Q000032:analysis; D001706:Biopsy; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000201:enzymology*; D000070818:Discoidin Domain Receptors; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000201:enzymology; D011237:Predictive Value of Tests; D011379:Prognosis; D011509:Proteoglycans / Q000032:analysis*; D011859:Radiography; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis*; D011975:Receptors, Mitogen / Q000032:analysis*; D012720:Severity of Illness Index; D013194:Staining and Labeling
chemical_list: D015415:Biomarkers; D011509:Proteoglycans; D011975:Receptors, Mitogen; D000070818:Discoidin Domain Receptors; D020794:Receptor Protein-Tyrosine Kinases
keywords: DDR2; Osteoarthritis; proteoglycans; tissue damage