Association between Serum Iron with Serum TNF-α, IL-6, IGF-1 and Lipids in Both Acute Myocardial Infarction and Unstable Angina Patients

Background: Pro-inflammatory cytokines (interleukine -6 and tumor necrotic factor-α) and Insulin-like growth factor-1 (IGF-1) play important roles in pathogenesis of acute myocardial infarction (AMI) and unstable angina (UA). In addition, serum iron overload or iron deficiency appears to be associated with atherosclerosis and ischemic myocardial damage. The aim of this investigation is to verify the role of inflammatory process and IGF-1 in pathophysiology of AMI and UA as well as to investigate the relationship of circulating IL-6, TNF-α and IGF-1 with the levels of serum iron and lipids in those patients. Methods: IL-6, TNF-α and IGF-1 were measured by ELISA assays in 18 patients with AMI and 18 patients with UA after their hospital admission, as well as in 6 healthy control subjects. Lipid profile was assessed by measuring the serum levels of total cholesterol, HDL-C, LDL-C and triglycerides. Serum iron was measured by atomic absorption flame emission spectrophotometer. Results: AMI patients with low serum iron showed significant higher levels of IL-6, TNF-α, LDL-C, cholesterol level and atherogenic index and lower levels of IGF-1 and HDL-C as compared with both low serum iron UA patients and healthy controls. On the other hand, AMI patients with high serum iron revealed non-significant differences in all previous parameters except IL-6 when compared with high serum iron UA patients. There was a significant positive correlation between serum iron with the levels of IGF-1 and HDL-C, as well as a significant negative correlation with the levels of cholesterol, triglycerides, LDL-C, TNF-α, and IL-6 in both AMI and UA patients with low serum iron. In addition, in AMI patients with high serum iron, a significant positive correlation between serum iron with IGF-1 and HDL-C and negative correlation with remaining parameters was evident. Conclusions: Both AMI and UA patients were associated with a pro-inflammatory state (increased TNF-α and IL-6), increased risky lipids (cholesterol, triglyceride, LDL-C, atherogenic index) and decreased cardiac protective factors, such as IGF-1 and HDL-C. These findings support the role of inflammation in both patients' population as well as the protective role of IGF-1 in ischemic heart disease. In addition, low serum iron in both AMI and UA patients was associated with more proinflammatory state and less cardiac protection than normal subjects or patients with either normal or high serum iron. However, the deleterious effects of low serum iron were more in AMI than UA patients.