Background It is known that patients with myocarditis of unknown etiology and with dilated cardiomyopathy show a high incidence of serum autoantibodies (M7) directed against mitochondrial flavoproteins. The tissue concentration of mitochondrial flavoproteins in the myocardium obtained from patients with dilated cardiomyopathy (DCM) was examined to further investigate the immunopathological mechanism of cardiomyopathy.
Methods and Results Myocardial tissue specimens were obtained from patients who underwent cardiac catheterization and a subendomyocardial biopsy for the diagnosis of cardiomyopathy. All samples were analyzed by Western blotting. NADH dehydrogenase ubiquinone flavoprotein (NDUFV1) production in the myocardium decreased significantly with DCM, in comparison to fumarate hydratase and flavoprotein SDHA. There was a significant negative-correlation between the left ventricular end-diastolic dimension and NDUFV1 production (R²=0.291, p value<0.05).
Conclusion NDUFV1 may be involved in the pathogenesis of DCM. A defect of mitochondrial NDUFV1 may reduce complex I, which produces most of the superoxide, which is then scavenged by the mitochondrial enzyme Mn-superoxide dismutase to produce H₂O₂. Exploring the nature of the candidate protein found in the myocardium in this study will provide further insight into the immunological mechanism of DCM.