Interleukin 6 G-174C polymorphism influences outcome following coronary revascularization surgery.
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.
Bittar
Mohamad N
MN
Department of Cardiothoracic Surgery, South Manchester University Hospitals NHS Trust, Manchester, UK. mbittar@doctors.org.uk
Carey
John A
JA
Barnard
James
J
Fildes
James E
JE
Pravica
Vera
V
Yonan
Nizar
N
Hutchinson
Ian V
IV
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
D015850:Interleukin-6; D006147:Guanine; D000225:Adenine