Histopathologic Evolution of Cardiomyopathy in a Canine Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a recessive X-linked disorder characterized for mutation in dystrophin gene and manifested by progressive degeneration and necrosis of skeletal and cardiac muscle with replacement leading to generalized muscular weakness and atrophy. The dog Golden Retriever Muscular Dystrophy (GRMD) is the best experimental model for DMD, with genotypic and phenotypic manifestations closely of human disease. Similar to patients with DMD, heart failure is a major cause of death in GRMD animals. The objective of this study was to evaluate the pathological progression of myocardial lesions from GRMD dogs in different ages in order to clarify the pathogenesis of Duchenne´s cardiomyopathy. Fragments of left and right ventricle and interventricular septum, from 18 GRMD dogs between 6 to 51 months were collected, fixed, dehydrated, clarified, and finally embedded in paraffin. Five micrometer thick serial sections were obtained and stained with Hematoxylin-Eosin (HE), Picrosirius red, and Von Kossa. Histological analyses were performed at the light microscopy. Myocardial lesions were observed in all GRMD dogs and the sequence of cardiac lesion classified according to according to the age included: abnormal calcium accumulation, myofibrillar necrosis, proliferation of granulation tissue, endomysial and perimysial fibrosis, and finally myocardial fatty infiltration. Interestingly, several Anitschkow cells, the hallmark of rheumatic carditis, were detected in inflammatory infiltrate present at granulation tissue. Our results demonstrate the sequence of cardiac lesions that determine the cardiomyopathy in Golden Retriever dogs affected by DMD and exhibit, for the first time, the Anitschkow cells in the histological findings of this cardiomyopathy. These results are relevant for to clarify the pathogenesis of cardiomyopathy in dogs and humans affected by DMD

Coronary microvascular disease in chronic Chagas cardiomyopathy including an overview on history, pathology, and other proposed pathogenic mechanisms.

This review focuses on the short and bewildered history of Brazilian scientist Carlos Chagas's discovery and subsequent developments, the anatomopathological features of chronic Chagas cardiomyopathy (CCC), an overview on the controversies surrounding theories concerning its pathogenesis, and studies that support the microvascular hypothesis to further explain the pathological features and clinical course of CCC. It is our belief that knowledge of this particular and remarkable cardiomyopathy will shed light not only on the microvascular involvement of its pathogenesis, but also on the pathogenetic processes of other cardiomyopathies, which will hopefully provide a better understanding of the various changes that may lead to an end-stage heart disease with similar features. This review is written to celebrate the 100th anniversary of the discovery of Chagas disease

Early dystrophin disruption in the pathogenesis of experimental chronic Chagas cardiomyopathy

Chronic Chagas cardiomyopathy evolves over a long period of time after initial infection by Trypanosoma cruzi. Similarly, a cardiomyopathy appears later in life in muscular dystrophies. This study tested the hypothesis that dystrophin levels are decreased in the early stage of T cruzi-infected mice that precedes the later development of a cardiomyopathy. CD1 mice were infected with T cruzi (Brazil strain), killed at 30 and 100 days post infection (dpi), and the intensity of inflammation, percentage of interstitial fibrosis, and dystrophin levels evaluated. Echocardiography and magnetic resonance imaging data were evaluated from 15 to 100 dpi. At 30 dpi an intense acute myocarditis with ruptured or intact intracellular parasite nests was observed. At 100 dpi a mild chronic fibrosing myocarditis was detected without parasites in the myocardium. Dystrophin was focally reduced or completely lost in cardiomyocytes at 30 dpi, with the reduction maintained up to 100 dpi. Concurrently, ejection fraction was reduced and the right ventricle was dilated. These findings support the hypothesis that the initial parasitic infection-induced myocardial dystrophin reduction/loss, maintained over time, might be essential to the late development of a cardiomyopathy in mice. (C) 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [07/58843-2, 07/59448-0, 09/17787-8, 09/53544-2, 09/54010-1, 10/19216-5, 10/18629-4, 10/13199-1]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) [472419/2009-9, 150723/2010-5]National Institutes of Health [AI076248]National Institutes of HealthFogarty International Training Grant [D43-TW007129]Fogarty International Training Gran

Changes of coronary perfusion in experimental <i>T. cruzi</i> infection and human chronic Chagas cardiomyopathy.

<p>(A) Microfil injection of the coronary vasculature of A/J mice infected with <i>T. cruzi</i> 15–17 days post-infection. Section of the atrium reveals saccular microaneurysms and vasospasm in the subendocardium. (B) Videomicrographs of representative fields of the microvasculature obtained from the cremaster muscle from <i>T. cruz</i>i–infected mice 20–25 days post-infection (a, arterioles; v, venules). Upper left and right panels: Representative fields showing areas of vasospasm (arrows). Left lower panel: In this field there is an area of segmental microvascular dilation (arrow). Right lower panel: Infected mouse treated with verapamil in which there were no areas of vasospasm or dilatation. Bar = 20 µm (from Tanowitz et al. (1996) Journal of Parasitology 82: 124–130, with permission of Allen Press and the Journal). (C) Planar images (anterior, left anterior oblique, and lateral views of myocardial scintigraphy with Tc-labelled microspheres in a chronic chagasic patient whose complaint was chest pain, but who had angiographycally normal coronary arteries. A prominent perfusion defect is seen in the anterolateral and posterolateral regions of the left ventricle. Courtesy of J. Antonio Marin-Neto, MD.</p

Study in mice chronically infected with <i>T. cruzi</i> demonstrating involvement of microcirculation.

<p>(A) Enlarged heart of a mouse infected with <i>T. cruzi</i> 100 days post-infection showing marked thinning of the apex of the left ventricle (apical aneurism). Bar = 2 mm. (B) Myocardium of an infected mouse stained by the Carstairs method for demonstration of platelets. An occlusive platelet thrombus is seen in a small epicardial vessel (arrowhead). Bar = 50 µm. Mononuclear cell infiltration, interstitial edema and fibrosis, and foci of myocytolytic necrosis. (C) Schematic representation of coronal sections through mice hearts infected with <i>T. cruzi</i> 100 days post-infection without (upper panel) and with (lower panel) apical aneurism, showing the extent of foci of myocytolytic necrosis. These areas are scattered throughout the ventricular and atrial myocardium, but are more numerous in the subendocardial and subepicardial regions in the apex, papillary muscles, and base of the ventricles. (D) Electron micrograph showing complete dissolution of myofibrils within a myofiber (*) of an infected mouse with characteristic myocytolysis or myocytolytic necrosis. Bar = 10 µm.</p

Micropathology of Chagas heart disease.

<p>(A) Acute myocarditis with foci of myocytolytic necrosis and degeneration are seen with an intense inflammatory infiltrate around ruptured pseudocysts of parasite (arrows, in the inset). Intact intramyocyte parasite nest without inflammatory response (arrow heads, in the inset). Hematoxylin and eosin staining. Bar = 100 µm; inset bar = 50 µm. (B) Chronic fibrosing myocarditis. Foci of myocytolytic necrosis associated with mononuclear inflammatory infiltrate and incipient interstitial fibrosis appearing in light blue (arrows). Gomori trichrome staining. Bar = 100 µm. (C) Chronic fibrosing myocarditis. Predominantly perimysial interstitial fibrosis extending to the endomysium (arrow heads) appearing in light blue associated with mononuclear inflammatory infiltrate. Gomori trichrome staining. Bar = 500 µm. (D) Chronic fibrosing myocarditis. Interstitial and diffuse fibrosis manifested by increased amount of thick collagen fibers surrounding muscle fiber bundles (perimysial matrix) and around intramural coronary vessels, combined with a less pronounced increase in the endomysial matrix. Picrosirius red staining. Bar = 500 µm.</p

Gross pathology of chronic Chagas cardiomyopathy (four-chamber frontal view).

<p>(A) Cardiomegaly with a left apical aneurysm (arrow). Myocardium hypertrophy. Marked thinning can be noted in the obtuse border of the heart at the submitral area (arrow head). At the apex of the right ventricle, distinct replacement of myocardial tissue by adipose tissue can be seen. (B) Cardiomegaly. Thinning and thrombosis at apices of both ventricles (arrow heads). Dilatation of cardiac ventricular chambers, mainly the right one. Fibrofatty substitution at the apex of the left ventricle and major part of the right ventricular free wall. (C) Normal-sized heart showing an enormous aneurysm at the apex of the left ventricle. Hypertrophy of the right ventricle free wall except for a marked thinned apex can be clearly seen. (D) Mildly enlarged heart showing dilatation of the four chambers. Giant left apical aneurysm. Thinning of left border of the heart immediately below the mitral valve. (E) Globally enlarged chronic chagasic heart with dilatation mainly affecting the right-sided chambers. Adipose replacement of the right ventricular myocardium, particularly at the apical region, associated with bulging can be seen (arrow heads). (F) Transillumination of a chagasic heart showing thinning of the muscle wall “cor bifidum” with aneurysm at the left apex (arrow heads), and marked thinning of the anteroapical region of the right ventricle. RV, right ventricle; LF, left ventricle. All bars = 3 cm.</p

Disruption of sarcolemmal dystrophin and beta-dystroglycan may be a potential mechanism for myocardial dysfunction in severe sepsis

Evidence from our laboratory has shown alterations in myocardial structure in severe sepsis/septic shock. The morphological alterations are heralded by sarcolemmal damage, characterized by increased plasma membrane permeability caused by oxidative damage to lipids and proteins. The critical importance of the dystrophin-glycoprotein complex (DGC) in maintaining sarcolemmal stability led us to hypothesize that loss of dystrophin and associated glycoproteins could be involved in early increased sarcolemmal permeability in experimentally induced septic cardiomyopathy. Male C57Bl/6 mice were subjected to sham operation and moderate (MSI) or severe (SSI) septic injury induced by cecal ligation and puncture (CLP). Using western blot and immunofluorescence, a downregulation of dystrophin and beta-dystroglycan expression in both severe and moderate injury could be observed in septic hearts. The immunofluorescent and protein amount expressions of laminin-alpha 2 were similar in SSI and sham-operated hearts. Consonantly, the evaluation of plasma membrane permeability by intracellular albumin staining provided evidence of severe injury of the sarcolemma in SSI hearts, whereas antioxidant treatment significantly attenuated the loss of sarcolemmal dystrophin expression and the increased membrane permeability. This study offers novel and mechanistic data to clarify subcellular events in the pathogenesis of cardiac dysfunction in severe sepsis. The main finding was that severe sepsis leads to a marked reduction in membrane localization of dystrophin and beta-dystroglycan in septic cardiomyocytes, a process that may constitute a structural basis of sepsis-induced cardiac depression. In addition, increased sarcolemmal permeability suggests functional impairment of the DGC complex in cardiac myofibers. In vivo observation that antioxidant treatment significantly abrogated the loss of dystrophin expression and plasma membrane increased permeability supports the hypothesis that oxidative damage may mediate the loss of dystrophin and beta-dystroglycan in septic mice. These abnormal parameters emerge as therapeutic targets and their modulation may provide beneficial effects on future cardiovascular outcomes and mortality in sepsis. Laboratory Investigation (2010) 90, 531-542; doi: 10.1038/labinvest.2010.3; published online 8 February 2010Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP[06/52882-3]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP[06/59618-0]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP[07/52556-1]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP[07/58843-2]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, FAPESP[07/59448-0]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, CNP