Apolipoprotein E genotype and circulating interleukin-10 levels in patients with stable and unstable coronary artery disease

OBJECTIVES This study was designed to assess the relation between apolipoprotein E (apoE) genotype and serum interleukin (IL)-10 levels in patients with acute coronary syndrome (ACS) and chronic stable angina (CSA). BACKGROUND Genetic variations in the apoE gene affect the risk for coronary artery disease (i.e., carriers of the e4 allele have an increased risk). Increased levels of C-reactive protein (CRP), an inflammatory marker, correlate with an increased risk of acute coronary events, whereas increased IL-10 concentrations have an atheroprotective role. Studies have reported a negative association between the apoE e4 allele and CRP levels. METHODS Apolipoprotein E genotypes were assessed in 166 consecutive ACS patients (119 men, mean age 68 years, interquartile range [IQR] 60 to 74 years) and 70 CSA patients (54 men, mean age 65 years, IQR 62 to 68 years). Serum IL-10 and CRP were assessed at study entry. RESULTS Analysis of covariance showed that genetic variation in the apoE gene locus significantly influences serum IL-10 levels in both ACS (p = 0.009) and CSA patients (p = 0.013). Among ACS patients, IL-10 levels were lower in E3/E4 carriers compared with E3/E3 carriers (p = 0.01) and marginally lower compared with E2/E3 carriers (p = 0.065). Among CSA patients, IL-10 levels were lower in E3/E4 carriers compared with E2/E3 carriers (p 0.004) and marginally lower compared with E3/E3 carriers (p = 0.086). CONCLUSIONS The IL-10 concentrations differ in ACS and in CSA patients with different apoE genotypes. The e4 allele was associated with a trend toward lower IL-10 serum levels. Our results may provide an explanation of findings in previous studies that cardiovascular risk is higher in e4 carriers despite the presence of low CRP levels.