Dilated cardiomyopathy (DCM)
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Publication
Journal: Nature
February/13/2002
Abstract
Cardiomyopathies are disorders affecting heart muscle that usually result in inadequate pumping of the heart. They are the most common cause of heart failure and each year kill more than 10,000 people in the United States. In recent years, there have been breakthroughs in understanding the molecular mechanisms involved in this group of conditions, with knowledge of the genetic basis for cardiomyopathies perhaps seeing the largest advance, enabling clinicians to devise improved diagnostic strategies and preparing the stage for new therapies.
Publication
Journal: Journal of Clinical Investigation
June/16/2004
Abstract
Today, dilated cardiomyopathy (DCM) represents the main cause of severe heart failure and disability in younger adults and thus is a challenge for public health. About 30% of DCM cases are genetic in origin; however, the large majority of cases are sporadic, and a viral or immune pathogenesis is suspected. Following the established postulates for pathogenesis of autoimmune diseases, here we provide direct evidence that an autoimmune attack directed against the cardiac beta(1)-adrenergic receptor may play a causal role in DCM. First, we immunized inbred rats against the second extracellular beta(1)-receptor loop (beta(1)-EC(II); 100% sequence identity between human and rat) every month. All these rats developed first, receptor-stimulating anti-beta(1)-EC(II) Ab's and then, after 9 months, progressive severe left ventricular dilatation and dysfunction. Second, we transferred sera from anti-beta(1)-EC(II)-positive and Ab-negative animals every month to healthy rats of the same strain. Strikingly, all anti-beta(1)-EC(II)-transferred rats also developed a similar cardiomyopathic phenotype within a similar time frame, underlining the pathogenic potential of these receptor Ab's. As a consequence, beta(1)-adrenergic receptor-targeted autoimmune DCM should now be categorized with other known receptor Ab-mediated autoimmune diseases, such as Graves disease or myasthenia gravis. Although carried out in an experimental animal model, our findings should further encourage the development of therapeutic strategies that combat harmful anti-beta(1)-EC(II) in receptor Ab-positive DCM patients.
Publication
Journal: Circulation
September/12/2001
Publication
Journal: Physiological Reviews
October/28/2002
Abstract
Cardiomyopathies are diseases of heart muscle that may result from a diverse array of conditions that damage the heart and other organs and impair myocardial function, including infection, ischemia, and toxins. However, they may also occur as primary diseases restricted to striated muscle. Over the past decade, the importance of inherited gene defects in the pathogenesis of primary cardiomyopathies has been recognized, with mutations in some 18 genes having been identified as causing hypertrophic cardiomyopathy (HCM) and/or dilated cardiomyopathy (DCM). Defining the role of these genes in cardiac function and the mechanisms by which mutations in these genes lead to hypertrophy, dilation, and contractile failure are major goals of ongoing research. Pathophysiological mechanisms that have been implicated in HCM and DCM include the following: defective force generation, due to mutations in sarcomeric protein genes; defective force transmission, due to mutations in cytoskeletal protein genes; myocardial energy deficits, due to mutations in ATP regulatory protein genes; and abnormal Ca2+ homeostasis, due to altered availability of Ca2+ and altered myofibrillar Ca2+ sensitivity. Improved understanding that will result from these studies should ultimately lead to new approaches for the diagnosis, prognostic stratification, and treatment of patients with heart failure.
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Publication
Journal: Cardiovascular Research
December/14/2003
Abstract
Myocarditis is a complex disease because multiple pathogenetic mechanisms play a role. While these mechanisms appear to act in a chronological cascade, they undoubtedly overlap in some cases, rendering diagnosis and treatment difficult. Ultimately, dilated cardiomyopathy (DCM) may result. A multitude of still-circumstantial evidence points to a major role of viral myocarditis in the etiology of DCM. The common presence of viral genetic material and viral proteins in the myocardium of patients with DCM provides the most compelling evidence, but proof of causality is still lacking. Nevertheless, because of the striking increase in heart failure prevalence in recent years, anti-viral and anti-inflammatory therapies should be developed for their potential to prevent or ameliorate DCM.
Publication
Journal: The Lancet
March/4/2002
Abstract
Cardiomyopathies are defined as diseases of the myocardium associated with cardiac dysfunction ranging from lifelong symptomless forms to major health problems such as progressive heart failure, arrhythmia, thromboembolism, and sudden cardiac death. They are classified by morphological characteristics as hypertrophic (HCM), dilated (DCM), arrhythmogenic right ventricular (ARVC), and restrictive cardiomyopathy (RCM). A familial cause has been shown in 50% of patients with HCM, 35% with DCM, and 30% with ARVC. In HCM, nine genetic loci and more than 130 mutations in ten different sarcomeric genes and in the gamma 2 subunit of AMP-activated protein kinase (AMPK) have been identified, suggesting impaired force production associated with inefficient use of ATP as the crucial disease mechanism. In DCM, 16 chromosomal loci with defects of several proteins also involved in the development of skeletal myopathies have been detected. These mutated cytoskeletal and nuclear transporter proteins may alter force transmission or disrupt nuclear function, resulting in cell death. Further DCM mutations have also been identified in sarcomeric genes, which indicates that different defects of the same protein can result in either HCM or DCM. In ARVC, six genetic loci and mutations in the cardiac ryanodine receptor, which controls electromechanical coupling, and in plakoglobin and desmoglobin (molecules involved in desmosomal cell-junction integrity), have been identified. Yet, no genetic linkage has been shown in RCM. Apart from disease-causing mutations, other factors, such as environment, genetic background, and the recently identified modifier genes of the renin-angiotensin, adrenergic, and endothelin systems are likely to result in the wide variety of RCM clinical presentations. Treatment options are symptomatic and are mainly focused on treatment of heart failure and prevention of thromboembolism and sudden death. Identification of patients with high risk for major arrhythmic events is important because implantable cardioverter defibrillators can prevent sudden death. Clinical and genetic risk stratification may lead to prospective trials of primary implantation of cardioverter defibrillators in people with hereditary cardiomyopathy.
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Journal: Viral Immunology
September/27/2006
Abstract
Coxsackievirus (CVB) infection is a significant cause of myocarditis and dilated cardiomyopathy (DCM). Heart disease may be caused by direct cytopathic effects of the virus, a pathologic immune response to persistent virus, or autoimmunity triggered by the viral infection. CVB interacts with its host at multiple stages during disease development. Signaling through viral receptors may alter the intracellular environment in addition to facilitating virus entry. Viral genetic determinants that encode cardiovirulence have been mapped and may change depending on the nutritional status of the host. Virus persistence is directly associated with pathology, and recent work demonstrates that CVB evolves into a slowly replicating form capable of establishing a low-grade infection in the heart. The innate immune response to CVB has taken on increasing importance because of its role in shaping the development of the adaptive immune response that is responsible for cardiac pathology. Studies of T cell responsiveness and the development of autoimmunity at the molecular level are beginning to clarify the mechanisms through which CVB infection causes inflammatory heart disease.
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Journal: Journal of Clinical Pathology
August/9/2009
Abstract
Dilated cardiomyopathy (DCM) is a common cardiac diagnosis that may result as a consequence of a variety of pathologies. The differential diagnosis remains quite broad since many pathologies can present as DCM, and as a result the approach to diagnosis may, at times, be quite difficult. This review article discusses genetic and acquired causes of DCM, pathophysiology of myocardial damage, pathology, and diagnostic criteria. An approach to management is also included, in the hope of informing physicians of a clinical entity that afflicts a substantial number of people worldwide.
Publication
Journal: Circulation Journal
June/29/2009
Abstract
Autoimmune abnormalities, as well as viral infection and genetic abnormalities, appear to be major predisposing factors for dilated cardiomyopathy (DCM). Abnormalities of cell-mediated immunity are mainly involved in the onset of cardiomyopathy secondary to myocarditis. However, various antimyocardial antibodies are detected in the serum of patients with DCM. The appearance of these antibodies was considered to be an epiphenomenon associated with myocyte injury resulting from myocarditis, but recent findings have suggested that at least some of them are directly related to the pathophysiology of DCM. In particular, an autoantibody targeting the beta1-adrenergic receptor that exhibits an agonist-like effect is related to the persistent myocardial damage resulting in DCM and provides substrates for fatal ventricular arrhythmias. In addition, an antibody for the muscarinic M2 receptor is related to atrial fibrillation, an antibody targeting Na-K-ATPase is closely related to sudden cardiac death as a result of fatal ventricular arrhythmias, and an autoantibody for troponin I increases the L-type calcium current and is related to the myocardial damage. Based on these findings, immunoadsorption therapy was developed to remove such autoantibodies in patients with refractory heart failure as a result of DCM.
Publication
Journal: Journal of Cardiac Failure
February/23/2009
Abstract
Dilated cardiomyopathy is a devastating disease associated with poor outcomes. Although the etiology of this disease remains largely unknown, so-called "idiopathic" dilated cardiomyopathy (iDCM) is associated with evidence of an autoimmune process that may be contributing to the pathophysiology of this disease. Indeed, iDCM shares many characteristics with other autoimmune diseases, including an association with systemic and organ-specific inflammation, an association with viral infections, a genetic predisposition, and a correlation with specific human leukocyte antigen subtypes. Additionally, numerous pathologic cardiac-specific autoantibodies have been associated with iDCM, including those against alpha-myosin, the beta(1)-adrenoceptor, and cardiac troponin I. This review highlights the emerging evidence regarding autoimmune characteristics of iDCM, and summarizes the data of specific immunomodulatory therapies used to target autoimmune mechanisms in the treatment of patients with this devastating disease.
Publication
Journal: Frontiers in Bioscience - Landmark
April/6/2009
Abstract
Myocarditis and dilated cardiomyopathy can potentially originate from autoimmune responses. Although genetic predisposition, viral infection, molecular mimicry, and oxidative stress are potential contributing factors to dilated cardiomyopathy, the underlying mechanism (s) has not been fully elucidated. Autoantibodies (AABs) against cardiotropic targets such as ss-adrenergic receptors, mitochondria proteins, myosin, tropomyocin and actin as well as structural proteins such as laminin and desmin may participate in the development of dilated cardiomyopathy. These autoantibodies disrupt cardiac excitation-contraction coupling and activate immune response to initiate tissue injury through complement and circulatory immunocomplexes (CICs). These antibodies are present prior to the onset of dilated cardiomyopathy and may be used to predict the deterioration of cardiac function. Depletion of these cardiac-specific antibodies by extracorporeal immunoabsorption has been considered as a new and effective approach in the treatment of autoimmunity-induced dilated cardiomyopathy. In order to better understand the pathogenesis and therapeutic remedy against this myopathy, the present review will summarize the manifestation and key signaling mechanisms involved in compromised cardiac contractile function during autoimmunity.