Serum anti-PCK1 antibody levels are prognostic factor for the patients with diabetes mellitus

Background: Autoantibodies develop in autoimmune diseases, cancer, diabetes mellitus (DM),and atherosclerosis-related diseases. However, autoantibody biomarkers have not been successfully examined for diagnosis and therapy. Methods: Serological identification of antigens through recombinant cDNA expression cloning (SEREX) was used for primary screening of antigens. The cDNA product was expressed in bacteria and purified. Amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) was used to evaluate antibody levels in serum samples. Results: Phosphoenolpyruvate carboxykinase 1 (PCK1) was recognized as an antigen by serum IgG antibodies in the sera of patients with atherosclerosis. AlphaLISA showed significantly higher serum antibody levels against recombinant PCK1 protein in patients with DM and cardiovascular diseasebut not in those with acute ischemic stroke, transient ischemic attack, or obstructive sleep apnea syndrome, than in healthy donors. The area under the receiver operating characteristic curve for anti-PCK1 antibodies was 0.7024 for DM. The serum anti-PCK1 antibody levels were associated with age, platelet count, and blood pressure. Anti-PCK1-antibody-positive patients showed significantly lower overall survival than the negative patients. Conclusions: Serum anti-PCK1 antibody levels were strongly associated with DM and weakly but significantly associated with cardiovascular disease. The anti-PCK1 antibody marker is useful for predicting the overall survival of patients with DM.