Enterovirus-induced myocardial injury can lead to severe heart failure. To date, little is known about the early innate stress response that contributes to host defense in the heart. Toll-like receptor 3 (TLR3) is important in the initiation of the innate antiviral response. We investigated the involvement of TLR3, which recognizes viral double-stranded RNA, on encephalomyocarditis virus (EMCV) infection. To examine the contribution of TLR3 in protection from EMCV infection, we infected mice deficient in TLR3 with 50 plaque-forming units of EMCV. TLR3-deficient (TLR3−/−) mice were more susceptible to EMCV infection and had a significantly higher viral load in the heart compared with TLR3+/+ mice. Histopathological examination showed that the inflammatory changes of the myocardium were less marked in TLR3−/− than in TLR3+/+mice. TLR3−/− mice had impaired proinflammatory cytokine and chemokine expression in the heart following EMCV infection. However, the expression of interferon-β was not impaired in EMCV-infected TLR3−/− mice. EMCV infection leads to a TLR3-dependent innate stress response, which is involved in mediating protection against virus-induced myocardial injury.

Objectives Four variants (K60N, Q128R, G202R and A592E) in the nebulette gene (NEBL) were identified in patients with dilated cardiomyopathy (DCM) and endocardial fibroelastosis (EFE). We sought to determine if these mutations cause cardiomyopathy. Background Nebulette aligns thin filaments and connects them with the myocardial Z-disk. Methods We produced transgenic mice with cardiac-restricted over-expression of human wild-type (WT) or mutant nebulette. Chimera and transgenic mice were examined at 4, 6 and 12 months of age by echocardiography and cardiac MRI. The hearts from embryos and adult mice were assessed by histopathologic, immunohistochemical, ultrastructural and protein analyses. Rat H9C2 cardiomyoblasts with transient expression of nebulette underwent cyclic mechanical strain. Results We identified lethal cardiac structural abnormalities in mutant embryonic hearts (K60N and Q128R). Founders of the mutant mice lines developed DCM with severe heart failure. An irregular localization pattern for nebulette and impaired desmin expression was noted in the proband and chimera Q128R mice. Mutant G202R and A592E mice exhibited left ventricular dilation and impaired cardiac function accompanied with the specific changes in I-band or Z-disk proteins by 6 months of age, respectively. The mutations modulated distribution of nebulette in the sarcomere and the Z-disks during stretch of H9C2 cells. Conclusions NEBL is a new susceptibility gene for EFE and DCM. Different mutations in nebulette trigger specific mechanisms converging to a common pathological cascade leading to EFE and DCM.

Phosphorylation and methylation of desmoplakin are required for proper junction assembly and adhesion strengthening, and inhibition of these modifications might contribute to skin and heart diseases.

Cardiopulmonary complications are the leading cause of mortality in sickle cell anemia (SCA). Elevated tricuspid regurgitant jet velocity, pulmonary hypertension, diastolic, and autonomic dysfunction have all been described, but a unifying pathophysiology and mechanism explaining the poor prognosis and propensity to sudden death has been elusive. Herein, SCA mice underwent a longitudinal comprehensive cardiac analysis, combining state-of-the-art cardiac imaging with electrocardiography, histopathology, and molecular analysis to determine the basis of cardiac dysfunction. We show that in SCA mice, anemia-induced hyperdynamic physiology was gradually superimposed with restrictive physiology, characterized by progressive left atrial enlargement and diastolic dysfunction with preserved systolic function. This phenomenon was absent in WT mice with experimentally induced chronic anemia of similar degree and duration. Restrictive physiology was associated with microscopic cardiomyocyte loss and secondary fibrosis detectable as increased extracellular volume by cardiac-MRI. Ultrastructural mitochondrial changes were consistent with severe chronic hypoxia/ischemia and sarcomere diastolic-length was shortened. Transcriptome analysis revealed up-regulation of genes involving angiogenesis, extracellular-matrix, circadian-rhythm, oxidative stress, and hypoxia, whereas ion-channel transport and cardiac conduction were down-regulated. Indeed, progressive corrected QT prolongation, arrhythmias, and ischemic changes were noted in SCA mice before sudden death. Sudden cardiac death is common in humans with restrictive cardiomyopathies and long QT syndromes. Our findings may thus provide a unifying cardiac pathophysiology that explains the reported cardiac abnormalities and sudden death seen in humans with SCA.sickle cell anemia | cardiomyopathy | restrictive physiology | arrhythmias | sudden death S ickle cell anemia (SCA) results from a point mutation in the β-globin gene and affects millions world-wide. It is characterized by production of the mutant hemoglobin S (HbS), which polymerizes upon deoxygenation and distorts the shape of RBCs, increasing their propensity to hemolysis and microvascular occlusion. Recurrent cycles of HbS polymerization result in a host of acute and chronic complications, including vaso-occlusive pain crisis, chronic hemolytic anemia, and organ damage. SCA-associated mortality rates have improved because of early diagnosis with universal newborn screening, immunization, and penicillin prophylaxis, which has changed the natural history of SCA (1, 2) and the impact of SCA on organ pathologies is now becoming evident.Despite improved early survival, nearly one-third of young adults with SCA die suddenly (3-9). The sickle myocardium has been presumed to be relatively resistant to the effects of sickling (10), and studies/autopsies show little evidence of atherosclerosis or coronary disease (11)(12)(13)(14). Mildly increased systolic pulmonary arterial pressure (PAP) estimated by tricuspid regurgitant jet vel...