title: Relationship of plasma interleukin-6 and its genetic variants with hypertension in Hong Kong Chinese.
abstract: BACKGROUND
  Interleukin-6 (IL6) plays a central role in inflammation, insulin resistance, and atherogenesis. We investigated the associations of plasma IL6 and its genetic variants with hypertension in both cross-sectional and prospective study designs.
  
  
  METHODS
  Plasma IL6 was measured in 648 normotensive and 294 hypertensive subjects from the Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS)-2 in 2000-2004 and three tagging single-nucleotide polymorphisms (SNPs) in the IL6 gene were genotyped. Among subjects normotensive in CRISPS-2 (baseline), 515 subjects were followed-up in CRISPS-3 in 2005-2008 and 100 of them had developed hypertension.
  
  
  RESULTS
  At baseline, plasma IL6 correlated with systolic blood pressure (SBP) (r = 0.128, P < 0.001). Hypertensive subjects had significantly higher plasma IL6 after adjusting for age and sex (geometric mean (95% confidence interval (CI) = 0.60 (0.54-0.65) vs. 0.47 (0.44-0.50) ng/l, P = 0.021). In multiple logistic regression, higher plasma IL6 was associated with hypertension in women (P = 0.009), but not in men. The minor G allele of SNP rs1800796 was associated with lower plasma IL6 (geometric mean (95% CI) = 0.46 (0.41-0.51) ng/l for CG and 0.49 (0.39-0.62) ng/l for GG vs. 0.53 (0.50-0.57) ng/l for CC, P = 0.005). However, this SNP was not associated with hypertension or blood pressure at baseline. Among subjects normotensive in CRISPS-2, plasma IL6 was not associated with the development of hypertension in CRISPS-3.
  
  
  CONCLUSIONS
  The SNP rs1800796 affected plasma IL6 with a small effect size. Elevated plasma IL6 is associated with prevalent hypertension in women, but not incident hypertension.
authors.affiliation: Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong. mycheung@hku.hk
authors.forename: Bernard M Y
authors.initials: BM
authors.lastname: Cheung
authors.forename: Kwok Leung
authors.initials: KL
authors.lastname: Ong
authors.forename: Annette W K
authors.initials: AW
authors.lastname: Tso
authors.forename: Raymond Y H
authors.initials: RY
authors.lastname: Leung
authors.forename: Stacey S
authors.initials: SS
authors.lastname: Cherny
authors.forename: Pak Chung
authors.initials: PC
authors.lastname: Sham
authors.forename: G Neil
authors.initials: GN
authors.lastname: Thomas
authors.forename: Tai Hing
authors.initials: TH
authors.lastname: Lam
authors.forename: Karen S L
authors.initials: KS
authors.lastname: Lam
mesh_terms: D000328:Adult; D044466:Asian People / Q000235:genetics*; D001794:Blood Pressure / Q000235:genetics; D003430:Cross-Sectional Studies; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000453:epidemiology / Q000235:genetics*; D015850:Interleukin-6 / Q000097:blood* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D012737:Sex Factors
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6