title: Clinical significance of serum YKL-40 in Behçet disease.
abstract: BACKGROUND
  Serum YKL-40 is an inflammatory biomarker of endothelial dysfunction and may play a role in the inflammatory process of Behçet disease (BD).
  
  
  OBJECTIVE
  Serum YKL-40 levels were evaluated in patients with BD in order to identify associations with other inflammatory cytokines and establish laboratory parameters. Serum YKL-40 levels were also compared with BD clinical features and disease activity.
  
  
  METHODS
  In total, 112 patients with BD and 45 age- and sex-matched healthy volunteers were included. Disease activity was assessed with BD Current Activity Form score and Electronic Medical Record-based Activity Index (EMRAI) score.
  
  
  RESULTS
  Serum YKL-40 levels were significantly higher in patients with BD (median 41·88, range 12·52-171·30 ng mL(-1) ) than in healthy volunteers (median 20·92, range 5·01-64·20 ng mL(-1) ; P < 0·01). The cut-off value for YKL-40 (30·005 ng mL(-1) ) was determined from the receiver operating characteristic curve. EMRAI scores and the proportion of patients in the active phase of BD presenting with two or more major criteria were significantly higher in patients with elevated YKL-40 levels (P = 0·04 and P = 0·04, respectively). A statistically significant elevation in YKL-40 levels was observed in patients with active BD compared with patients with inactive BD (P = 0·05). Serum YKL-40 values were positively correlated with interleukin-6 and EMRAI scores (both P = 0·04), indicating that serum YKL-40 levels are increased in patients with BD and positively correlate with disease activity.
  
  
  CONCLUSIONS
  YKL-40 may play a role in the pathophysiology of BD and provide a useful marker for monitoring patients with BD.
authors.affiliation: Department of Dermatology and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: J
authors.initials: J
authors.lastname: Seo
authors.affiliation: Department of Dermatology and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Y
authors.initials: Y
authors.lastname: Ahn
authors.affiliation: Department of Dermatology and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul, Korea.|Department of Dermatology, Yanbian University Hospital, Yanji, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Biostatistics Collaboration Unit, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: B O
authors.initials: BO
authors.lastname: Kim
authors.affiliation: Department of Dermatology and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: M J
authors.initials: MJ
authors.lastname: Choi
authors.affiliation: Department of Dermatology, Catholic Kwandong University, International St. Mary's Hospital, Incheon, Korea.
authors.forename: D
authors.initials: D
authors.lastname: Bang
authors.affiliation: Department of Dermatology and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: D Y
authors.initials: DY
authors.lastname: Kim
mesh_terms: D000328:Adult; D001528:Behcet Syndrome / Q000097:blood*; D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D000071451:Chitinase-3-Like Protein 1 / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve
chemical_list: D015415:Biomarkers; D000071451:Chitinase-3-Like Protein 1; D015850:Interleukin-6