Elevated Levels of Autoantibodies against ATP2B4 and BMP-1 in Sera of Patients with Atherosclerosis-related Diseases

Atherosclerosis-related life-style diseases such as cerebral infarction (CI), cardiovascular disease (CVD), diabetes mellitus (DM), and chronic kidney disease (CKD) are a serious problem in the recently aging society. The development of novel and sensitive diagnostic markers is necessary and expected for the early treatment. Through the first screening by phage expression cloning, we identified ATPase, Ca++ transporting, plasma membrane 4 (ATP2B4) and bone morphogenetic protein 1 (BMP-1) as antigens recognized by IgG antibodies in the sera of patients with atherosclerosis. The presence of autoantibodies against these antigens in serum specimens was confirmed by Western blotting. We then compared serum antibody levels against recombinant ATP2B4 and BMP-1 proteins between healthy donors (HD) and patients with atherosclerotic diseases, such as CI, transient ischemic attack (TIA), CVD, DM, or CKD, by the Alpha (amplified luminescent proximity homogeneous assay)-LISA method. The results revealed that both antibody levels were significantly higher in patients with these diseases than in HD and exhibited most prominent differences in CKD vs. HD. Correlation analysis showed that both antibody levels were well correlated with the degree of artery stenosis, such as maximum intima-media thickness with some different patterns, i.e., anti-ATP2B4 antibody levels were related to hypertension, whereas anti-BMP-1 antibodies were related to smoking habits. The serum antibody levels against ATP2B4 and BMP-1 can be useful diagnostic markers for atherosclerosis and its related diseases caused by hypertension and smoking habits, respectively.