Homocysteine is positively associated with cytokine IL-18 plasma levels in coronary artery bypass surgery patients

Homocysteine, cytokines (IL-18, IL-6, IL-8) are involved in vascular inflammation and coronary artery disease. Homocysteine influences endothelial IL-6 and IL-8 cytokine expression and release, however, an association between homocysteine and IL-18 has not been previously investigated in endothelial/smooth muscle cells and or in coronary artery disease. We report in 9 coronary artery bypass surgery (CABG) patients a positive correlation r=0.86 between homocysteine and IL-18 plasma levels (p<0.05). Plasma IL-18 levels are significantly higher in those patients with elevated homocysteine compared to those with normal levels (p<0.02; 153 ± 19 pg/ml versus 116 ± 14 pg/ml respectively). Our in vitro cell culture studies suggest that the source of IL-18 in CABG patients with elevated homocysteine is not from vascular smooth muscle or endothelial cells.