title: Interleukin 6 G-174C polymorphism influences outcome following coronary revascularization surgery.
abstract: BACKGROUND
  Levels of the proinflammatory cytokine interleukin 6 (IL-6) increase after surgery. The functional polymorphism in the IL-6 promoter region, G-174C, is associated with an increased risk of coronary heart disease. We investigated the genetic predisposition in IL-6 response to coronary revascularization and studied the association between the G-174C polymorphism, IL-6 levels, and clinical outcomes of surgery.
  
  
  METHODS
  DNA was obtained from 96 consecutive patients who underwent elective coronary revascularization. Patients were genotyped for the IL-6 G-174C polymorphism by means of sequence-specific primer-polymerase chain reaction analysis. IL-6 levels were measured with an enzyme-linked immunosorbent assay on serum samples taken 3 hours postoperatively. IL-6 levels and genotypes (CC, CG, and GG) were correlated with perioperative clinical data.
  
  
  RESULTS
  The prevalences of the CC, CG, and GG IL-6 -174 genotypes were 8%, 54%, and 38%, respectively. Patients homozygous for the C allele had higher circulating levels of IL-6 postoperatively than the patients with the CG and GG genotypes (P = .09). Patients homozygous for the G allele had a significantly lower incidence of postoperative atrial fibrillation (P = .032) and a shorter hospital stay (P = .005). This result remained statistically significant following risk stratification. The severity of coronary artery disease and a higher number of bypass grafts were associated with a significant increase in IL-6 level postoperatively (P = .028, and P = .005, respectively). Higher levels of IL-6 were associated with increased blood loss postoperatively (P = .016).
  
  
  CONCLUSIONS
  The C allele is associated with higher postoperative IL-6 levels and a less favorable clinical outcome. The G-174C polymorphism is related to the outcome after coronary revascularization.
authors.affiliation: Department of Cardiothoracic Surgery, South Manchester University Hospitals NHS Trust, Manchester, UK. mbittar@doctors.org.uk
authors.forename: Mohamad N
authors.initials: MN
authors.lastname: Bittar
authors.forename: John A
authors.initials: JA
authors.lastname: Carey
authors.forename: James
authors.initials: J
authors.lastname: Barnard
authors.forename: James E
authors.initials: JE
authors.lastname: Fildes
authors.forename: Vera
authors.initials: V
authors.lastname: Pravica
authors.forename: Nizar
authors.initials: N
authors.lastname: Yonan
authors.forename: Ian V
authors.initials: IV
authors.lastname: Hutchinson
mesh_terms: D000225:Adenine; D000368:Aged; D000483:Alleles; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000209:etiology; D016063:Blood Loss, Surgical / Q000706:statistics & numerical data; D001026:Coronary Artery Bypass / Q000009:adverse effects; D003327:Coronary Disease / Q000235:genetics* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006147:Guanine; D006720:Homozygote; D006801:Humans; D015994:Incidence; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011184:Postoperative Period; D011446:Prospective Studies; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D015850:Interleukin-6; D006147:Guanine; D000225:Adenine