Association between antibodies against calcifying nanoparticles and mitral annular calcification.

Background and Aim of the Study: Mechanisms leading to vascular and tissue calcification are not yet fully understood. Previously, an association has been demonstrated between a controversial calcifying nanoparticle (CNP; also known as 'nanobacteria') and vascular calcification and kidney stone formation. The study aim was to evaluate a possible association between mitral annular calcification (MAC) and CNP infection.
Methods: A total of 93 patients with MAC, detected using echocardiography, and 94 asymptomatic subjects without valvular and coronary artery calcification, were enrolled in the study. The serum levels of anti-CNP-antibodies were monitored in all subjects.
Results: Patients with MAC were generally older and had a higher prevalence of systemic hypertension, diabetes mellitus, and dyslipidemia. The anti-CNP-antibody titers, which were significantly associated with MAC (p < 0.0001), were increased with older age and MAC thickness, but decreased in line with serum levels of HDL-cholesterol (p < 0.0001). In order to provide a cut-off point for anti-CNP-antibodies when detecting MAC, a receiver operating characteristic curve was created. Serum CNP-antibody levels above 0.19 units/ml showed a sensitivity of 73%, a specificity of 72%, and positive and negative predictive values of 72% and 73%, respectively. Multivariate logistic regression analysis revealed that increasing age, systemic hypertension, diabetes, HDL-cholesterol levels and high anti-CNP titers were risk factors that were independently associated with calcification in the mitral annuli.
Conclusion: The study results suggested that CNP might play an important role in the pathogenesis of MAC.