Myocardial inflammatory cell infiltrates in cases of dilated cardiomyopathy: light microscopic, immunohistochemical, and virological analyses of myocardium specimens obtained by partial left ventriculectomy

Diagnostic utility of tenascin-C for evaluation of the activity of human acute myocarditis

Tenascin-C (TN-C) is an extracellular matrix protein that is expressed transiently in close association with tissue remodelling in various body sites. In the heart, TN-C is only present during early stages of development, is not expressed in the normal adult, but reappears in pathological states. The purpose of this study was to analyse the expression of TN-C in myocardial tissue from myocarditis patients, and to evaluate the diagnostic value of immunostaining for TN-C in the assessment of inflammatory activity in biopsy specimens. A total of 113 biopsy specimens obtained from 32 patients with a clinical diagnosis of acute myocarditis were examined by immunohistochemistry and in situ hybridization for TN-C. The immunostaining was semi-quantified and compared with histological diagnosis according to the Dallas criteria. Furthermore, serial biopsies from 22 patients were taken during convalescence, and sequential changes in TN-C levels were analysed. Expression of TN-C was specifically detected in endomyocardial biopsy specimens from patients with active-stage inflammation, and disappeared in healed stages. The degree of expression of TN-C correlated with the severity of histological lesions. These data suggest that TN-C reflects disease activity in cases of human myocarditis. Immunostaining for TN-C could enhance the sensitivity and accuracy of diagnosis using biopsy specimens.

sICAM-1 correlates with myocardial ICAM-1 expression in dilated cardiomyopathy

BACKGROUND

Dilated cardiomyopathy (DCM) is etiopathogenically linked to intramyocardial inflammation, which is reflected by ICAM-1 abundance. We investigated whether soluble ICAM-1 (sICAM-1) levels in the sera of DCM patients are associated with intramyocardial ICAM-1 expression.

METHODS

Immunohistochemically detected ICAM-1 expression was quantified semiquantitatively in endomyocardial biopsies from DCM patients (n=45; n=17 females; age: 48+/-15 years) and from n=12 donor hearts (controls) by a human observer (baseline vs. enhanced expression) and quantitatively by a digital image analysis (DIA) system. The DIA-measured qualities were area fraction (AF), surface-volume ratio (SVR) and integral optical density (ID). The sICAM-1 levels of the DCM patients and n=12 healthy volunteers (controls) were measured by ELISA (means of duplicate measurements). Intramyocardial ICAM-1 expression and sICAM-1 levels were compared in these DCM patients.

RESULTS

Of the DCM patients, n=24 (53%) demonstrated statistically higher sICAM-1 levels compared to controls (>198 ng/ml). By semiquantitative and quantitative DIA evaluation, endothelial ICAM-1 abundance was present in n=25 (56%) of the DCM biopsies. sICAM-1 correlated significantly (P<0.001) both with the semiquantitatively assessed and the DIA-measured ICAM-1-AF, the ICAM-1-SVR and the ICAM-1-ID. The positive predictive value of sICAM-1 measurements for intramyocardial ICAM-1 abundance was 96%, and the negative predictive value was 71%, with a receiver operating characteristic area under the curve of 0.93. Furthermore, sICAM-1 levels correlated with intramyocardial T-lymphocytic (CD2+/CD3+) infiltrates (P<0.03).

CONCLUSIONS

Measurement of non-invasively obtained sICAM-1 reliably reflects intramyocardial ICAM-1 expression and may therefore serve as a non-invasive marker of inflammatory activity in DCM.

Cytotoxic perforin+ and TIA-1+ infiltrates are associated with cell adhesion molecule expression in dilated cardiomyopathy

OBJECTIVE

To phenotypically characterize cytotoxic T-lymphocytes (CTLs: Perforin+ and TIA-1+ phenotypes) and to study the interactions with cell adhesion molecules (CAMs) in dilated cardiomyopathy (DCM).

BACKGROUND

DCM is linked to intramyocardial inflammation, being characterized by T-lymphocytic infiltration and CAMs abundance. However, the pathogenic significance of increased CD3+ lymphocytes remains obscure as these do not correlate with CTLs (perforin+ and TIA1+ phenotypes). CAMs participate in the phenotypic repertoire and effector pathways of CTLs.

METHODS

CAMs-expression (ICAM-1, VCAM-1, LFA-3, CD29, CD62E and CD62P and beta(2)-integrins), CD3+ (T-lymphocytes), CD57+ (NK-cells) and adhesion related (CD18+, CD11a+, CD11b+, CDw49d+) phenotyped infiltrates were investigated in endomyocardial biopsies (EMBs) from 89 DCM patients (33 female; LVEF<40%) using immunohistochemisty. The enteroviral genome was identified by nested RT-PCR.

RESULTS

CAMs abundance was confirmed in 55 DCM patients (62%) and 29 EMBs (33%) were graded CTLs+ (>1.5 TIA-1+ and/or >2.0 perforin+ infiltrates/hpf). CTLs correlated with all endothelial CAMs-markers studied (P<0.01), the adhesion related phenotypes of infiltrates (LFA-1, VLA-4, CD18) and CD57+ NK-cells (P<0.02). There was no correlation of CTLs with CD3+ T-lymphocytes, CD11b+ macrophages, enteroviral infection (present in n=16/18%), clinical history and LVEF (P>0.05). Phenomena suggestive of CTLs mediated myocytolysis were observed in 10 patients (11%).

CONCLUSIONS

CTLs-infiltrates are associated with endothelial CAMs-abundance and co-express adhesion related (beta2-integrins, VLA-4) and NK-cellular antigens (CD57) in DCM. Endothelial CAMs expression also reflects cytotoxic activation of intramyocardial infiltrates, which is not reflected by immunologically nai;ve CD3 T-lymphocytes.

Quantitative analysis of cytokine mRNA expression in hearts from patients with nonischemic dilated cardiomyopathy (DCM)

PURPOSE AND METHODS

There is increasing evidence that inflammatory cytokines play an important role in the development of heart failure. To evaluate the role of cytokines in nonischemic DCM, we analyzed the relative quantity of cytokine mRNA expression in the hearts from DCM patients with refractory heart failure, using the ABI PRISM7700 real-time PCR system. We used heart tissues resected from 32 DCM patients at the time of elective partial ventriculectomy (PLV), and five biopsy specimens with normal histological findings as control.

RESULTS AND DISCUSSION

Interleukin (IL)-1beta, IL-10, and Tumor Necrosis Factor (TNF)-alpha mRNA were expressed at low levels in all normal hearts. The number of IL-10-positive DCM cases was significantly smaller than normal controls (P = 0.0036). One (10%) of 10 DCM patients with IL-10 mRNA expression died after PLV, and 10 (45%) of 22 DCM patients without IL-10 mRNA expression died. IL-1beta mRNA was overexpressed (over twice the mean of control subjects) in 15 of 32, and TNF-alpha mRNA in 10 of 32 patients. We propose the classification of DCM patients into subgroups on the basis of cytokine mRNA expression. Anticytokine therapy or cytokine therapy may have potential in improving the condition of heart failure in certain subgroups of DCM patients.

CONCLUSIONS

We suggest that DCM patients with heart failure deteriorate without IL-10 mRNA expression in the myocardium. The classification of DCM patients into subgroups on the basis of cytokine mRNA expression may have great value in considering the treatment of this heterogeneous disease state.

Immunomodulatory effect of pentoxifylline in suppressing experimental autoimmune myocarditis

Although a recent clinical study reported the beneficial effects of pentoxifylline (PTX), a phosphodiesterase inhibitor, on both symptoms and cardiac function in dilated cardiomyopathy (DCM), the precise mechanism of the drug has not been delineated. This study examined the efficacy of PTX in the treatment of experimental autoimmune myocarditis (EAM), as a model of the autoimmune mechanism involved in DCM. Oral PTX, or saline as control, was administered to Lewis rats at 150mg/kg body weight per day bid daily from 5 days before immunization with cardiac myosin until death on Day 21. Histological examination of the hearts showed PTX significantly reduced the severity of EAM. mRNA expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, IL-6, and IL-10 was significantly reduced in peripheral blood mononuclear cells, but expression of IL-4 and IL-6 was upregulated in heart tissue. PTX in vitro could suppress T cell proliferation and inhibit TNF-alpha and interferon-gamma production. In conclusion, the immunomodulatory effects of PTX had a significant therapeutic result in EAM. This is the first report to describe such an effect of PTX in a specific animal model for DCM.

Autophagic degeneration as a possible mechanism of myocardial cell death in dilated cardiomyopathy

In failing hearts, cardiomyocytes degenerate and interstitial fibrosis, which indicates cardiomyocyte loss, becomes more prominent in the myocardium. However, the precise mechanism of cardiomyocyte degeneration that leads to cell death is still unclear, although it is presumed that lysosomal function and autophagy play an important role because lysosomal activity increases under stress such as hypoxia. Myocardium that had been resected during partial left ventriculectomy performed in patients with dilated cardiomyopathy (DCM) was examined. Under light microscopy, some cardiomyocytes had a marked scarcity of myofibrils and had prominent cytoplasmic vacuolization. Atrophic and degenerated cardiomyocytes were often observed adjacent to replacement fibrotic tissue. Immunohistochemistry showed positivity for lysosome-associated membrane protein and a lysosomal catheptic enzyme in vacuoles of various sizes in the cardiomyocytes and these lysosomal markers were markedly increased in atrophic and degenerated cardiomyocytes. Electron microscopy revealed that degenerated cardiomyocytes had many vacuoles containing intracellular organelles, such as mitochondria, and were considered to be autophagic vacuoles. In DCM hearts, autophagy appeared to be associated not only with degradation of damaged intracellular organelles but also with progressive destruction of cardiomyocytes. It is possible that autophagic degeneration is one of the mechanisms of myocardial cell death.

Myocardial inflammatory cell infiltrates in cases of dilated cardiomyopathy as a determinant of outcome following partial left ventriculectomy

Partial left ventriculectomy (PLV) can be used to treat refractory congestive heart failure caused by dilated cardiomyopathy (DCM). In order to understand the relationship between the underlying myocardial injury and early clinical outcomes after PLV, histopathologic, immunohistochemical and virologic studies of the resected myocardium were performed. The posterolateral left ventricular walls from 27 patients with idiopathic DCM were examined. Cardiomyocyte diameter, degree of myocardial fibrosis, degree of cardiomyocyte degeneration, and degree of inflammatory cell infiltration were compared with mortality rates. Polymerase chain reaction was performed to detect enterovirus genome in the myocardium. Some patients had inflammatory cell infiltrates with focal accumulations of lymphocytes and macrophages, including both cytotoxic/suppressor T-cells and helper/inducer T-cells. The number of inflammatory cells (activated lymphocytes plus macrophages/mm2) was significantly greater in patients who died of cardiac insufficiency after surgery (27.8 +/- 5.7; n = 7) than in the survivors (11.1 +/- 2.5; n = 15). There was no significant difference in the degree of myocardial fibrosis, cardiomyocyte diameter or degree of cardiomyocyte degeneration between the 2 groups. Enterovirus genome was detected in the myocardium of 9 (38%) of 24 patients examined and 5 of these enterovirus-positive hearts had severe inflammatory cell infiltrates (37.9 +/- 2.5/mm2). Early survival in patients undergoing PLV for DCM is significantly affected by the degree of myocardial inflammation, so patients with more severe or ongoing inflammation may have poor clinical outcomes. Chronic myocarditis may play an important role in the etiology and pathophysiology of idiopathic DCM.

A case of cardiomyopathy showing progression from the hypertrophic to the dilated form: association of Mt8348A-->G mutation in the mitochondrial tRNA(Lys) gene with severe ultrastructural alterations of mitochondria in cardiomyocytes

This report describes a case of cardiomyopathy with a novel point mutation of mitochondrial DNA coding lysine tRNA in association with severe ultrastructural alterations of the mitochondria in the cardiomyocytes. Abnormalities of energy production and/or abnormal protein synthesis because of the mutation of mitochondrial DNA may have played an important role in the pathogenesis of this case, which showed severe cardiomyocyte degeneration and deterioration from hypertrophic cardiomyopathy to severe dilated cardiomyopathy.

Current perspectives of partial left ventriculectomy in the treatment of dilated cardiomyopathy

OBJECTIVES

Partial left ventriculectomy has been performed as an alternative to heart transplantation in the treatment of severe cardiomyopathies. This investigation documents the clinical and left ventricular (LV) function effects of this procedure, associated, when necessary, with mitral insufficiency correction, in 43 patients with idiopathic dilated cardiomyopathy.

METHODS

Eighteen patients were in New York Heart Association class III and 25 in class IV. Seven of them were operated in cardiogenic shock. The procedure was associated with mitral annuloplasty in 32 patients and mitral replacement in three.

RESULTS

Nine patients (20.9%) died during the hospital period and the cause of death was associated with ventricular failure in seven patients. The other patients were followed up from 2 to 57 months (mean, 28.3 months). At 6 months of follow-up, eight patients were in functional class I, 13 in class II, three in class III and one patient was in class IV (P<0.001). On the other hand, nine patients died during the first 6 months and another six in the later postoperative period. The cause of late death was progressive heart failure in eight patients, and seven patients died because of arrhythmia related events. The actuarial survival was 58.1+/-7.5% at 1 year and 43.9+/-8.1% at 4 years of follow-up. Regarding ventricular function modifications, the LV diastolic volume decreased by around 25% and the LV ejection fraction increased from 17.8+/-4.7 to 22.3+/-7.9% (P<0.001), whereas significant changes in the cardiac index, stroke index and pulmonary pressures were also found 1 month after the operation. In the later follow-up, despite the maintenance of hemodynamic improvement, the LV diastolic volume tended to increase and returned to preoperative levels at 4 years, while a concomitant decrease in the LV ejection fraction was also observed.

CONCLUSION

Partial left ventriculectomy associated with mitral insufficiency correction improves LV function and ameliorates congestive heart failure in patients with idiopathic cardiomyopathy. Otherwise, the LV function benefits seem to be restricted by the possibility of progressive LV redilatation. Furthermore, the clinical application of this procedure is limited by the high mortality observed in the first postoperative months and by the possibility of heart failure progression and arrhythmia related events at late follow-up.

Enterovirus RNA replication in cases of dilated cardiomyopathy: light microscopic in situ hybridization and virological analyses of myocardial specimens obtained at partial left ventriculectomy

OBJECTIVE

Recently, attention has been focused on enteroviral infection of the heart in the genesis of dilated cardiomyopathy (DCM). To determine the location of enteroviral RNA in the myocardium, we performed light microscopic in situ hybridization (ISH) and virological analyses of myocardial specimens obtained at partial left ventriculectomy (PLV).

METHODS

Posterolateral walls of the left ventricle from 26 DCM patients were examined. Myocardial specimens were tested for the presence of enteroviral genomes by polymerase chain reaction (PCR). We selected two age-matched groups (10 patients each) in which enteroviruses were either present (EV-plus group) or not (EV-minus group). For both groups, we examined in situ localization of enteroviral RNA in the myocardium by ISH.

RESULTS

In PCR studies, both sense and antisense enteroviral RNA were detected in the myocardium of seven patients in the EV-plus group. The presence of this RNA indicates active viral replication in the myocardium. Five of seven patients who exhibited both sense and antisense enteroviral RNA died early after surgery. On ISH, three patients had evidence of active replication of enteroviral genomes. Viral genomes were present in myocardial lesions, especially in endocardial sites. Viral signals were found in degenerating myocardial cells, interstitial inflammatory cells, and endothelial cells of small vessels. These positive signals were not detected in the myocardium of the EV-negative group.

CONCLUSIONS

We detected both sense and antisense enteroviral RNA in various myocardial lesions. This suggests that active enteroviral replication plays a role in the development of myocardial lesions in DCM patients. Active viral replication appears to be a prognostic factor for DCM after PLV. Further study of active viral replication in myocardial lesions will provide information useful for evaluating different therapeutic strategies for DCM.