title: Serum YKL-40 as a marker of disease activity and stricture formation in patients with Crohn's disease.
abstract: OBJECTIVE
  YKL-40 is secreted by macrophages and neutrophils and is a growth factor for vascular endothelial cells and fibroblasts. Elevated serum levels of YKL-40 have been reported in patients with various inflammatory conditions and ongoing fibrosis. The aim of this study was to investigate the relationship between serum concentrations of YKL-40 and disease activity, acute phase reactants, and the presence of strictures in patients with Crohn's disease (CD).
  
  
  METHODS
  We studied the serum concentrations of YKL-40 in 41 patients with CD, in which 12 had an endoscopically- or radiologically-proven stricture formation. Forty-six age- and sex-matched healthy volunteers served as controls and a multivariate regression analysis was performed to find out the independent predictors of intestinal strictures and clinical activity.
  
  
  RESULTS
  The serum YKL-40 concentrations in the patients were significantly higher than that in the healthy controls (105.69 +/- 88.08 ng/mL [range 20.23-333.57]vs 44.92 +/- 24.89 ng/mL [range 18.31-113.43], P = 0.000) and patients with a stricture formation had significantly higher YKL-40 levels than those without strictures (167.50 +/- 119.30 ng/mL [range 23.62-333.57]vs 80.12 +/- 56.38 ng/mL [range 20.23-259.19], P = 0.003). Significant correlations were noted between YKL-40 levels and clinical activity (r = 0.681; P = 0.000) and the presence of intestinal strictures (r = 0.457; P = 0.003). The multivariate regression analysis found the serum YKL-40 levels to be an independent predictor of intestinal strictures (P = 0.001) and clinical activity (P = 0.001).
  
  
  CONCLUSIONS
  Patients with CD, particularly those with a stricture formation, have significantly higher levels of YKL-40. YKL-40 seems to be a useful marker of disease activity as well as stricture formation in patients with CD.
authors.affiliation: Department of Gastroenterology, Istanbul University, Cerrahpasa Medical Faculty, Istanbul, Turkey. dryusuf@doruk.net.tr
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Erzin
authors.forename: Hafize
authors.initials: H
authors.lastname: Uzun
authors.forename: Adem
authors.initials: A
authors.lastname: Karatas
authors.forename: Aykut Ferhat
authors.initials: AF
authors.lastname: Celik
mesh_terms: D054392:Adipokines; D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D000071451:Chitinase-3-Like Protein 1; D003251:Constriction, Pathologic / Q000097:blood / Q000209:etiology; D003424:Crohn Disease / Q000097:blood* / Q000150:complications; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D037102:Lectins; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D054392:Adipokines; D015415:Biomarkers; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D037102:Lectins