Profiling of serum autoantibodies against apolipoprotein A-1 in the diagnosis of ischemic heart disease

Background: Ischemic heart disease (IHD) involves complex inflammatory and immune-mediated processes. Autoantibodies against apolipoprotein A-1 (anti-apoA-1 IgG) are emerging mediators of atherogenesis. This study aimed to profile serum anti-apoA-1 IgG alongside a panel of novel and traditional biomarkers to evaluate their diagnostic utility and interrelationships in IHD. Methods: This cross-sectional study enrolled 280 participants: 100 with stable angina pectoris (SAP), 100 with acute myocardial infarction (AMI), and 80 healthy controls. Serum levels of anti-apoA-1 IgG, high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), lipoprotein-associated phospholipase A2 (Lp-PLA2), myeloperoxidase (MPO), and oxidised LDL (ox-LDL) were measured. Standard lipid profiles were also assessed. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis. Results: Serum anti-apoA-1 IgG levels were significantly higher in both IHD patient groups compared to the control group (p<0.001), with AMI patients having higher levels than SAP patients (p<0.01). Furthermore, all biomarkers associated with inflammation and oxidative stress (hs-CRP, IL-6, Lp-PLA2, MPO, ox-LDL) were elevated in IHD patients. Anti-apoA-1 IgG showed a significant positive correlation with IL-6 (r=0.51, p<0.001) and MPO (r=0.45, p<0.001). In ROC analysis using multiple biomarkers, the combination of anti-apoA-1 IgG, IL-6, and ox-LDL yielded an AUC of 0.89 (95% CI: 0.85-0.93) for the diagnosis of IHD. Conclusion: Anti-apoA-1 IgG was significantly higher in IHD patients, especially in the acute phase of the disease, and was associated with markers of inflammation and oxidative stress. The inclusion of multiple markers, such as anti-apoA-1 IgG, IL-6, and ox-LDL, improves the diagnostic performance for ischemic heart disease. This approach yielded better diagnostic accuracy than using each marker individually.