Serum Anti-AP3D1 Antibodies Are Broad-Spectrum Biomarkers for Atherosclerosis, Acute Ischemic Stroke, Cardiovascular Disease, Diabetes Mellitus, Chronic Kidney Disease, and Digestive Organ Cancer

Abstract Background: Atherosclerosis has been considered as the main cause of morbidity, mortality, premature incapacity, and disability worldwide. For early and sensitive diagnosis, development of novel biomarkers is expected and of significant practical importance.Methods: The first screening for antigen markers was conducted using the serological identification of antigens by recombinant cDNA expression cloning (SEREX). Serum antibody levels were examined using the amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) using a recombinant protein as an antigen.Results: SEREX screening has identified adaptor-related protein complex 3 subunit delta 1 (AP3D1) as an antigen recognized by serum IgG antibodies of patients with atherosclerosis. As per the results of AlphaLISA, it was determined that the serum antibody levels against AP3D1 were higher in patients with acute ischemic stroke (AIS), transient ischemic attack (TIA), diabetes mellitus (DM), cardiovascular disease (CVD), chronic kidney disease (CKD), esophageal squamous cell carcinoma (ESCC), and colorectal carcinoma than those in the healthy donors. The area under the curve values of DM, nephrosclerosis type of CKD, and ESCC calculated using receiver operating characteristic curve analysis were noted to be higher than that of other diseases. Correlation analysis showed that the anti-AP3D1 antibody levels were highly associated with maximum intima-media thickness, which indicates that this marker reflected the development of atherosclerosis. The Japan Public Health Center-based Prospective Study results have verified that the serum antibody levels against AP3D1 showed significantly higher odds ratios with the risk of AIS for persons with the third quartiles and the highest quartiles versus the lowest quartile, indicating that this antibody marker is deemed useful as risk factors for AIS.Conclusions: Serum anti-AP3D1 antibodies, which are broad-spectrum biomarkers of atherosclerotic diseases and digestive organ cancers, could be useful in predicting the onset of AIS.