Background: Inflammation is an important phenomenon in atherosclerotic plaque growth and in plaque instability. Cytokines are nuclear mediators in the inflammatory response; some have proinflammatory and others anti-inflammatory roles. Proinflammatory cytokines have been associated with worse outcomes in unstable angina. The aims of this study were to determine the role of the anti-inflammatory cytokine interleukin (IL)-10 and the proinflammatory to anti-inflammatory ratios in the short-term prognosis of patients with unstable angina.
Methods: Serum levels of proinflammatory cytokines IL-1beta, IL-6, and IL-8, and of the anti-inflammatory cytokine IL-10 were determined on admission in 127 consecutive patients with severe unstable angina, and comparisons were made between patients who had cardiovascular events (death, nonfatal myocardial infarction, readmission for refractory angina) (n = 20) and patients without coronary events (n = 107) during a follow-up period of 3 months.
Results: IL-10 levels were lower (0.67 +/- 1.13 vs 1.33 +/- 1.67 pg/mL, P =.04) and IL-8 levels were higher (3.6 +/- 2.41 vs 2.23 +/- 2.47 pg/mL, P =.029) in patients in whom cardiovascular events subsequently developed compared with those without events, with resulting higher proinflammatory to anti-inflammatory cytokine ratios in the former group, whereas no significant differences were seen in IL-1beta or IL-6 levels between the groups, except for the subgroup of patients with prolonged rest angina and persistent electrocardiographic changes. A greater ratio of IL-8 to IL-10 serum levels was observed in patients who had coronary events (28 +/- 25 vs 12 +/- 21, P =.007). The risk of subsequent coronary events increased in patients in the highest quartile of proinflammatory to anti-inflammatory cytokine ratio (IL-8/IL-10). Patients in the highest quartile had a relative risk 3.8 times higher than those in the lowest quartile (P =.01).
Conclusions: Lower levels of IL-10, with higher proinflammatory to anti-inflammatory cytokine ratios, were observed on admission in patients with unstable angina who subsequently had cardiovascular events. Higher levels of the anti-inflammatory cytokine IL-10 may be needed to provide protection in unstable angina.