title: Higher levels of interleukin-6 are associated with lower echogenicity of carotid artery plaques.
abstract: OBJECTIVE
  Echo-lucent carotid plaques can be fragile and vulnerable to rupture, representing a risk factor for ischemic stroke. Given the studies showing that elevated levels of circulating inflammatory markers are predictive of cardiovascular events, we sought to determine whether higher levels of serum interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) are associated with lower echogenicity of carotid plaques.
  
  
  METHODS
  The study comprised 246 patients who had carotid atherosclerotic plaques as evidenced by ultrasound. Using acoustic densitometry, we quantified the echogenicity of the largest plaque in each patient by integrated backscatter analysis. Serum IL-6 and hsCRP levels were determined in all patients.
  
  
  RESULTS
  Both log-transformed IL-6 and hsCRP concentrations were negatively correlated with carotid plaque echogenicity (r=-0.28, P<0.001, and r=-0.14, P<0.05, respectively). When traditional atherosclerotic risk factors, plaque thickness, and medication use were controlled for, IL-6 levels were inversely associated with plaque echogenicity (beta=-0.21, P<0.01), whereas such an association was of borderline significance for hsCRP (beta=-0.12, P=0.06).
  
  
  CONCLUSIONS
  Higher IL-6 levels, in addition to hsCRP levels, appear to be associated with lower echogenicity of carotid plaques, suggesting a link between inflammation and potential risk of plaques.
authors.affiliation: Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan. yamagami@medone.med.osaka-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamagami
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kitagawa
authors.forename: Yoji
authors.initials: Y
authors.lastname: Nagai
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Hougaku
authors.forename: Manabu
authors.initials: M
authors.lastname: Sakaguchi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kuwabara
authors.forename: Kimito
authors.initials: K
authors.lastname: Kondo
authors.forename: Tohru
authors.initials: T
authors.lastname: Masuyama
authors.forename: Masayasu
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Hori
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D016893:Carotid Stenosis / Q000097:blood* / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D015850:Interleukin-6 / Q000097:blood*; D007564:Japan / Q000453:epidemiology; D008297:Male; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014463:Ultrasonography
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators; D015850:Interleukin-6; D002097:C-Reactive Protein