The role of endothelin-1 in myocarditis and inflammatory cardiomyopathy: old lessons and new insights

Pathogenesis and Prevention of Radiation-induced Myocardial Fibrosis

Radiation therapy is one of the most important methods for the treatment of malignant tumors. However, in radiotherapy for thoracic tumors such as breast cancer, lung cancer, esophageal cancer, and mediastinal lymphoma, the heart, located in the mediastinum, is inevitably affected by the irradiation, leading to pericardial disease, myocardial fibrosis, coronary artery disease, valvular lesions, and cardiac conduction system injury, which are considered radiation-induced heart diseases. Delayed cardiac injury especially myocardial fibrosis is more prominent, and its incidence is as high as 20–80%. Myocardial fibrosis is the final stage of radiation-induced heart diseases, and it increases the stiffness of the myocardium and decreases myocardial systolic and diastolic function, resulting in myocardial electrical physiological disorder, arrhythmia, incomplete heart function, or even sudden death. This article reviews the pathogenesis and prevention of radiation-induced myocardial fibrosis for providing references for the prevention and treatment of radiation-induced myocardial fibrosis.

Carboxiterminal pro-endothelin-1 as an endothelial cell biomarker in thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is characterised by the deficiency of the von Willebrand factor (VWF) cleaving protease (ADAMTS-13). Although several observations indicate an important role of endothelial activation in the pathogenesis of TTP, no reliable endothelial activation markers are available in the clinical management of TTP. Our aim was to investigate the presence of endothelial activation in TTP and to determine its connections with disease activity, therapy and complement activation. We enrolled 54 patients (median age 40.5; 44 females) and 57 healthy controls (median age 34; 30 females),VWF antigen, carboxiterminal-pro-endothelin-1 (CT-proET-1), complement Factor H and complement activation products (C3bBbP and SC5b-9) were measured. In both the acute and remission phase of TTP we found increased CT-proET-1 and VWF levels, while Factor H levels decreased compared with healthy controls. In remission, however, the elevated CT-proET-1 levels showed 22 % decrease when compared with the acute phase in paired samples (p=0.0031), whereas no changes for VWF and Factor H levels were observed. We also found positive correlations between CT-proET-1 levels and alternative pathway activation markers (C3bBbP; p=0.0360; r=0.4299). The data we present here demonstrate a role of endothelium activation in patients with acute TTP. The finding that CT-proET-1 levels decreased in remission compared with the acute phase further supports endothelial involvement. In addition, we show that endothelial activation also correlated with the activation of the alternative complement pathway. The data suggest that complement and endothelium activation jointly contribute to the development of TTP episodes in patients with predisposition to TTP.

Recognizing and treating myocarditis in recent-onset systemic sclerosis heart disease: potential utility of immunosuppressive therapy in cardiac damage progression

OBJECTIVES

Scleroderma heart disease is a major risk of death in systemic sclerosis (SSc). Mechanisms underlying myocardial damage are still unclear. We performed an extensive study of SSc patients with recent-onset symptoms for heart disease and examined the efficacy of immunosuppressive therapy.

METHODS

A cohort of 181 SSc patients was enrolled. Of these, 7 patients newly developed clinical symptoms of heart disease (heart failure, chest pain, and palpitation); all of them showed mild but persistent increase in cardiac enzymes. These patients underwent Holter ECG, 2D-echocardiography, perfusional scintigraphy, delayed-enhancement-cardiac magnetic resonance (DE-CMR), coronary angiography, and endomyocardial biopsy. Patients were treated for at least 12 months and followed-up for 5 years.

RESULTS

Ventricular ectopic beats (VEBs) were found in 4 patients, wall motion abnormalities in 3, pericardial effusion in 6, and DE in CMR in 6 with T2-hyperintensity in 2. In all patients, histology showed upregulation of endothelium adhesion molecules and infiltration of activated T lymphocytes, with (acute/active myocarditis in 6) or without (chronic/borderline myocarditis in 1) myocyte necrosis. Parvovirus B19 genome was detected in 3. None showed occlusion of coronary arteries or microvessels. Compared with SSc controls, these patients more often had early disease, skeletal myositis, c-ANCA/anti-PR3 positivity, VEBs, pericardial effusion, and systolic and/or diastolic dysfunction. Immunosuppressive therapy improved symptoms and led to cardiac enzyme negativization; however, 2 patients died of sudden death during follow-up.

CONCLUSIONS

Myocarditis is a common finding in SSc patients with recent-onset cardiac involvement. Its early detection allowed to timely start an immunosuppressive treatment, preventing cardiac damage progression in most cases.

Ambient temperature and biomarkers of heart failure: a repeated measures analysis

BACKGROUND

Extreme temperatures have been associated with hospitalization and death among individuals with heart failure, but few studies have explored the underlying mechanisms.

OBJECTIVES

We hypothesized that outdoor temperature in the Boston, Massachusetts, area (1- to 4-day moving averages) would be associated with higher levels of biomarkers of inflammation and myocyte injury in a repeated-measures study of individuals with stable heart failure.

METHODS

We analyzed data from a completed clinical trial that randomized 100 patients to 12 weeks of tai chi classes or to time-matched education control. B-type natriuretic peptide (BNP), C-reactive protein (CRP), and tumor necrosis factor (TNF) were measured at baseline, 6 weeks, and 12 weeks. Endothelin-1 was measured at baseline and 12 weeks. We used fixed effects models to evaluate associations with measures of temperature that were adjusted for time-varying covariates.

RESULTS

Higher apparent temperature was associated with higher levels of BNP beginning with 2-day moving averages and reached statistical significance for 3- and 4-day moving averages. CRP results followed a similar pattern but were delayed by 1 day. A 5°C change in 3- and 4-day moving averages of apparent temperature was associated with 11.3% [95% confidence interval (CI): 1.1, 22.5; p = 0.03) and 11.4% (95% CI: 1.2, 22.5; p = 0.03) higher BNP. A 5°C change in the 4-day moving average of apparent temperature was associated with 21.6% (95% CI: 2.5, 44.2; p = 0.03) higher CRP. No clear associations with TNF or endothelin-1 were observed.

CONCLUSIONS

Among patients undergoing treatment for heart failure, we observed positive associations between temperature and both BNP and CRP-predictors of heart failure prognosis and severity.

Potential targets for intervention in radiation-induced heart disease

Radiotherapy of thoracic and chest wall tumors, if all or part of the heart was included in the radiation field, can lead to radiation-induced heart disease (RIHD), a late and potentially severe side effect. RIHD presents clinically several years after irradiation and manifestations include accelerated atherosclerosis, pericardial and myocardial fibrosis, conduction abnormalities, and injury to cardiac valves. The pathogenesis of RIHD is largely unknown, and a treatment is not available. Hence, ongoing pre-clinical studies aim to elucidate molecular and cellular mechanisms of RIHD. Here, an overview of recent pre-clinical studies is given, and based on the results of these studies, potential targets for intervention in RIHD are discussed.

Electrical remodelling precedes heart failure in an endothelin-1-induced model of cardiomyopathy

AIMS

Binary transgenic (BT) mice with doxycycline (DOX)-suppressible cardiac-specific overexpression of endothelin-1 (ET-1) exhibit progressive heart failure (HF), QRS prolongation, and death following DOX withdrawal. However, the molecular basis and reversibility of the electrophysiological abnormalities in this model were not known. Here, we assess the mechanisms underlying ET-1-mediated electrical remodelling, and its role in HF.

METHODS AND RESULTS

BT vs. non-BT littermate controls were withdrawn from DOX and serially studied with ultrasound biomicroscopy, octapolar catheters, multielectrode epicardial mapping, histopathology, western blot, immunohistochemistry, and qRT-PCR. Abnormalities in ventricular activation and -dV/dt were detected as early as 4 weeks after transgene activation, when the structure and function of the heart remained unaffected. By 8 weeks of ET-1 overexpression, biventricular systolic and diastolic dysfunction, myocardial fibrosis, and cardiomyocyte hypertrophy were observed. Intracardiac and epicardial electrograms revealed prolonged conduction and ventricular activation, reduced -dV/dt, and abnormal atrioventricular nodal function. Within 4 weeks of ET-1 induction, connexin 40 (Cx40) protein and Cx43 mRNA, protein, and phosphorylation levels were reduced by 36, 64, 93, and 69%, respectively; Na(v)1.5 mRNA and protein levels were reduced by 30 and 50%, respectively, as was Na(+) channel conductance. Importantly, the associated electrophysiological abnormalities at this time point were reversible upon suppression of ET-1 overexpression and completely prevented the development of structural and functional remodelling.

CONCLUSION

ET-1-mediated electrical remodelling correlates with reduced Cx40, Cx43, and Na(v)1.5 expression and decreased Na(+) channel conductance and precedes HF. The sequence and reversibility of this phenotype suggest that a primary abnormality in electrical remodelling may contribute to the pathogenesis of HF.

Preclinical research into basic mechanisms of radiation-induced heart disease

Radiation-induced heart disease (RIHD) is a potentially severe side effect of radiotherapy of thoracic and chest wall tumors if all or part of the heart was included in the radiation field. RIHD presents clinically several years after irradiation and manifestations include accelerated atherosclerosis, pericardial and myocardial fibrosis, conduction abnormalities, and injury to cardiac valves. There is no method to prevent or reverse these injuries when the heart is exposed to ionizing radiation. This paper presents an overview of recent studies that address the role of microvascular injury, endothelial dysfunction, mast cells, and the renin angiotensin system in animal models of cardiac radiation injury. These insights into the basic mechanisms of RIHD may lead to the identification of targets for intervention in this late radiotherapy side effect.

Alterations in biomarkers of cardiovascular disease (CVD) in active acromegaly

OBJECTIVES

In acromegalic patients, cardiovascular and metabolic comorbidities contribute to enhance mortality. Available data on the lipoprotein profile of these patients are controversial. Our aim was to characterize the lipoprotein profile and emergent biomarkers of cardiovascular disease in active acromegalic patients in comparison with sex- and age-matched healthy controls.

PATIENTS

Eighteen patients with active acromegaly and 18 controls were studied.

MEASUREMENTS

Glucose levels, hormonal status, lipoprotein profile and C reactive protein (CRP) were evaluated by standardized methods. Cholesteryl ester transfer protein (CETP) and lipoprotein-associated phospholipase A(2 )(Lp-PLA(2)) were measured by radiometric techniques, endothelin-1 and vascular cell adhesion molecule (VCAM)-1 by enzyme-linked immunosorbent assay, and leucocytes CD18, CD49d and CD54 by flow cytometry.

RESULTS

After adjusting for body mass index (BMI), acromegalic patients presented a more atherogenic lipoprotein profile, consisting of higher levels of triglycerides and apolipoprotein B and alterations in the ratios which estimate insulin resistance and atherogenic risk. CETP activity was significantly increased in acromegalic patients as compared to controls (168 +/- 17 vs. 141 +/- 30% per ml h, respectively; P < 0.05). Endothelin-1 levels evidenced an increase in the patients' group (0.9 +/- 0.2 vs. 0.7 +/- 0.2 ng/l, respectively; P < 0.01) and showed positive and significant correlations with GH, IGF-1 and IGFBP-3 (r = 0.45, 0.42 and 0.44, respectively; P < 0.01 for all of them; with BMI as a fixed variable). Lymphocytes from acromegalic patients showed increased CD49d content (282 +/- 59 vs. 246 +/- 48 arbitrary units, respectively; P < 0.05).

CONCLUSIONS

Taken together, the alterations described seem to contribute to constituting a state of higher propensity for the development of atherosclerotic cardiovascular disease, which adds to the presence of specific cardiomyopathy.

Influence of endothelin 1 receptor inhibition on functional, structural and molecular changes in the rat heart after irradiation

Radiation-induced heart disease is a severe side effect of thoracic radiotherapy. Studies suggest that mast cells play a protective role in radiation-induced heart disease and that the endothelin (ET) system mediates protective effects of mast cells in other disorders. This study examined whether mast cells modulate the cardiac ET system and examined the effects of ET receptor inhibition in a rat model of radiation-induced heart disease. Mast cell-deficient (Ws/Ws), mast cell-competent (+/+) and Sprague-Dawley rats received 18 Gy irradiation to the heart. Left ventricular mRNA of ET1 and its receptors (ETA and ETB) was measured in Ws/Ws and +/+ rats at 1 week and 3 months. Sprague-Dawley rats were treated with the ETA/ETB antagonist bosentan, and at 6 months cardiac changes were assessed using the Langendorff perfused rat heart preparation, immunohistochemistry and real-time PCR. Ws/Ws and +/+ rat hearts did not differ in baseline mRNA. In contrast, +/+ rats hearts exhibited up-regulation of ET1 after irradiation, whereas Ws/Ws rats hearts did not, suggesting the possibility of interactions between mast cells and the cardiac ET system. Bosentan induced reductions in left ventricular systolic pressure, developed pressure and +dP/dtmax but did not affect fibrosis. Because of the known opposing effects of ETA and ETB, studies with selective antagonists may clarify the role of each receptor.

Mechanisms of endothelin-1-induced MAP kinase activation in adrenal glomerulosa cells

G protein-coupled receptors (GPCRs) such as angiotensin II, bradykinin and endothelin-1 (ET-1) are critically involved in the regulation of adrenal function, including aldosterone production from zona glomerulosa cells. Whereas, substantial data are available on the signaling mechanisms of ET-1 in cardiovascular tissues, such information in adrenal glomerulosa cells is lacking. Bovine adrenal glomerulosa (BAG) cells express receptors for endothelin-1 (ET-1) and their stimulation caused phosphorylation of Src (at Tyr416), proline-rich tyrosine kinase (Pyk2 at Tyr402), extracellularly regulated signal kinases (ERK1/2), and their dependent proteins, p90 ribosomal S6 kinase (RSK-1) and CREB. ET-1 elicited these responses predominantly through activation of a G(i)-linked cascade with a minor contribution from the G(q)/PKC pathway. Whereas, selective inhibition of EGF-R kinase with AG1478 caused complete inhibition of EGF-induced ERK/RSK-1/CREB activation, it caused only partial reduction (30-40%) of such ET-1-induced responses. Consistent with this, inhibition of matrix metalloproteinases (MMPs) with GM6001 reduced ERK1/2 activation by ET-1, consistent with partial involvement of the MMP-dependent EGF-R activation in this cascade. Activation of ERK/RSK-1/CREB by both ET-1 and EGF was abolished by inhibition of Src, indicating its central role in ET-1 signaling in BAG cells. Moreover, the signaling characteristics of ET-1 in cultured BAG cells closely resembled those observed in clonal adrenocortical H295R cells. The ET-1-induced proliferation of BAG and H295 R cells was much smaller than that induced by Ang II or FGF. These data demonstrate that ET-1 causes ERK/RSK-1/CREB phosphorylation predominantly through activation of G(i) and Src, with a minor contribution from MMP-dependent EGF-R transactivation.