Background
In addition to pathogenic autoantibodies, polyclonal autoantibodies with unknown physiological roles and pathogenicity are produced in the body. Moreover, serum antibodies against the proprotein convertase subtilisin/kexin type 9 (PCSK9) protein, which is integral to cholesterol metabolism, have also been observed. Therefore, we aimed to examine the clinical significance of PCSK9 antibody (PCSK9-Ab) levels.
Methods
We measured blood PCSK9-Ab and PCSK9 protein levels in 109 healthy donors (HDs) and 274 patients with diabetes mellitus (DM) (type 2 DM: 89.8%) using an amplified luminescence proximity homogeneous assay-linked immunosorbent assay. Subsequently, patients with DM were followed up (mean: 4.93 years, standard deviation: 2.77 years, maximum: 9.58 years, minimum: 0.07 years) to examine associations between antibody titers and mortality, myocardial infarction, stroke onset, and cancer.
Results
Although PCSK 9-Ab levels were significantly higher in the DM group than in the HDs group, PCSK9 protein levels were not significantly different. PCSK9-Ab and PCSK9 protein levels showed no correlation in either group. Mortality was significantly associated with higher PCSK9-Ab levels, but unrelated to PCSK9 protein levels. After investigating for potential confounding factors, PCSK9-Ab levels were significantly associated with prognosis in patients with DM.
Conclusions
PCSK9-Ab may be a novel prognostic marker in patients with diabetes, and further studies are warranted to verify its usefulness.