title: YKL-40 and cytokines - a New Diagnostic Constellation in Rheumatoid Arthritis?
abstract: BACKGROUND
  Rheumatoid arthritis (RA) causes chronic inflammation and alteration of articular tissue and joints. The pathogenesis of the disease remains unclear although it is known that proinflammatory cytokines play a major role in its induction. YKL-40 is a chitinase-like glycoprotein produced by activated macrophages, neutrophils, arthritic chondrocytes and cancer cells. It has been shown that YKL-40 is implicated in tissue remodeling, angiogenesis and inflammation.
  
  
  OBJECTIVE
  to investigate serum and synovial YKL-40 levels in relation to IL-1β, TNF-α, and IL-6 in RA patients.
  
  
  METHODS
  Serum and synovial concentrations of YKL-40, TNF-α, IL- 6, and IL-1β were determined by ELISA in 39 patients (mean age 53.18 ± 16.54 yrs) with active RA.
  
  
  RESULTS
  Serum YKL-40 levels were increased in all patients. The highest levels were found in synovial fluid (P<0.01). Our study showed a strong association between serum and synovial levels of YKL-40 and serum TNF-α and IL-1 β (P<0.05).
  
  
  CONCLUSIONS
  This is the first study finding a significant correlation between serum TNF-α and IL-1β and YKL-40 in active RA. We suggest that these molecules together might play a dominant role in the pathogenesis and disease activity and could possibly serve as a new diagnostic constellation in rheumatoid arthritis.
authors.affiliation: Department of Medical Biology, Faculty of Medicine, Medical University of Plovdiv, 15A Vasil Aprilov Blvd., 4002 Plovdiv.
authors.forename: Maria H
authors.initials: MH
authors.lastname: Kazakova
authors.affiliation: Department of Propedeutics of Internal Diseases, Faculty of Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria.
authors.forename: Anastas Z
authors.initials: AZ
authors.lastname: Batalov
authors.affiliation: Department of Medical Informatics, Biostatistics and E-learning, Faculty of Public Health, Medical University of Plovdiv, Plovdiv.
authors.forename: Nonka G
authors.initials: NG
authors.lastname: Mateva
authors.affiliation: Clinic of Rheumatology, Medical University of Sofia, Sofia.
authors.forename: Zlatimir G
authors.initials: ZG
authors.lastname: Kolarov
authors.affiliation: Department of Medical Biology, Faculty of Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria.
authors.forename: Victoria S
authors.initials: VS
authors.lastname: Sarafian
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging / Q000276:immunology*; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000276:immunology; D016022:Case-Control Studies; D000071451:Chitinase-3-Like Protein 1 / Q000276:immunology*; D016207:Cytokines / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D053583:Interleukin-1beta / Q000276:immunology; D015850:Interleukin-6 / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D013582:Synovial Fluid / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology; D014463:Ultrasonography
chemical_list: C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D016207:Cytokines; C508585:IL1B protein, human; C508600:IL6 protein, human; D053583:Interleukin-1beta; D015850:Interleukin-6; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein
keywords: YKL-40; cytokines; rheumatoid arthritis