Ubiquitin, p62, and Microtubule-Associated Protein 1 Light Chain 3 in Cardiomyopathy.

Background: The accumulation of ubiquitinated proteins has been detected in diseased hearts and has been associated with the expression of p62 and microtubule-associated protein 1 light chain 3 (LC3), which are related to autophagy. We evaluated differences in ubiquitin accumulation and p62 and LC3 expression in cardiomyopathy using endomyocardial biopsies. Methods and Results: We studied 24 patients (aged 24-70 years; mean age 55 years) diagnosed with dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), or non-cardiomyopathy (NCM) who underwent endomyocardial biopsy. Biopsied samples were evaluated by microscopy for ubiquitin accumulation and expression of p62 and LC3. Ubiquitin accumulation and p62 and LC3 expression were observed in all patients. Ubiquitin accumulation was higher in DCM than in HCM or NCM; p62 expression was higher in DCM than in HCM. There were no significant differences in LC3 expression among the groups. Ubiquitin accumulation was significantly related to serum N-terminal pro B-type natriuretic peptide concentration and the expression of p62, but not LC3. Conclusions: Ubiquitin accumulation was more prominent in DCM than in HCM and NCM, which may be due to a relative shortage of clearance, including autophagy, compared with production.

Pathological features of biopsied myocardium in patients clinically diagnosed with peripartum cardiomyopathy.

The etiology of peripartum cardiomyopathy (PPCM) is unknown. Therefore, we evaluated the etiology of patients clinically diagnosed with PPCM using endomyocardial biopsy. We studied five patients diagnosed with PPCM following endomyocardial biopsy (age, 28-42 years; mean age, 35 years). Biopsied samples were evaluated using microscopy, including immunostaining and electron microscopy. The pathological findings were as follows: myocardial hypertrophy, myocardial fibrosis, and cell infiltration. Two patients were diagnosed with lymphocytic myocarditis, one with eosinophilic myocarditis, one with hypertensive heart disease, and one with a combination of hypertension and myocarditis. Endomyocardial biopsy suggested that the causes of PPCM were varied and related to myocarditis and myocardial overload due to hypertension.

Histopathological changes of myocytes in restrictive cardiomyopathy.

Restrictive cardiomyopathy (RCM) is a rare primary myocardial disease, and its pathological features are yet to be determined. Restrictive cardiomyopathy with MHY7 mutation was diagnosed in a 65-year-old Japanese woman. Electron microscopy of a myocardial biopsy revealed electron-dense materials resulting from focal myocyte degeneration and necrosis as well as tubular structures and pseudo-inclusion bodies in some nuclei. These features may be associated with the pathogenesis of RCM.

Pathological findings of myocardium in a patient with cardiac conduction defect associated with an SCN5A mutation.

A 16-year-old Japanese man was admitted to our hospital because of syncope during exercise. His father and his younger brother had permanent pacemaker implantation because of sick sinus syndrome. Several examinations revealed first-degree atrioventricular block, complete right bundle branch block, sick sinus syndrome, and ventricular tachycardia with normal cardiac function. As no abnormalities were evident on coronary angiography, right ventricular endomyocardial biopsy was performed. It showed myocardial disarrangement and lipofuscin accumulation in hypertrophic myocytes. Moreover, electron microscopy showed a few degenerative myocytes, Z-band streaming, disarrangement, increased small capillaries with Weibel-Palade bodies in endothelial cells, and endothelial proliferations. Genetic analysis of the proband, his father, and his younger brother revealed a missense mutation, D1275N, in SCN5A, a gene which encodes sodium ion channel protein, are related to cardiomyopathy and arrhythmia. The proband was diagnosed with a cardiac conduction defect (CCD) and underwent permanent pacemaker implantation. These pathological findings suggest various myocardial changes presented in CCD patients with a missense mutation, D1275N, in SCN5A.

A case of chronic myocarditis.

Chronic myocarditis is sometimes difficult to diagnose using several clinical diagnostic modalities. A 43-year-old Japanese man was admitted to our hospital with heart failure due to a diffusely hypokinetic left ventricle. No abnormal accumulation was seen on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography. Coronary angiography showed no abnormalities. Endomyocardial biopsy was performed on suspicion of dilated cardiomyopathy, revealing diffuse cell infiltration (more T lymphocytes associated with macrophages than B cells on immunohistochemical staining), myocyte damage, and replacement fibrosis. The pathological diagnosis of biopsy specimen was difficult to differentiate between chronic myocarditis and inflammatory dilated cardiomyopathy without immunohistochemistry. Endomyocardial biopsy offers one of the most useful methods for diagnosing chronic myocarditis.