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Therapeutic Modulation of the Immune Response in Arrhythmogenic Cardiomyopathy.

ABSTRACT: BACKGROUND:Inflammation is a prominent feature of arrhythmogenic cardiomyopathy (ACM), but whether it contributes to the disease phenotype is not known. METHODS:To define the role of inflammation in the pathogenesis of ACM, we characterized nuclear factor-?B signaling in ACM models in vitro and in vivo and in cardiac myocytes from patient induced pluripotent stem cells. RESULTS:Activation of nuclear factor-?B signaling, indicated by increased expression and nuclear accumulation of phospho-RelA/p65, occurred in both an in vitro model of ACM (expression of JUP2157del2 in neonatal rat ventricular myocytes) and a robust murine model of ACM (homozygous knock-in of mutant desmoglein-2 [Dsg2mut/mut]) that recapitulates the cardiac manifestations seen in patients with ACM. Bay 11-7082, a small-molecule inhibitor of nuclear factor-?B signaling, prevented the development of ACM disease features in vitro (abnormal redistribution of intercalated disk proteins, myocyte apoptosis, release of inflammatory cytokines) and in vivo (myocardial necrosis and fibrosis, left ventricular contractile dysfunction, electrocardiographic abnormalities). Hearts of Dsg2mut/mut mice expressed markedly increased levels of inflammatory cytokines and chemotactic molecules that were attenuated by Bay 11-7082. Salutary effects of Bay 11-7082 correlated with the extent to which production of selected cytokines had been blocked. Nuclear factor-?B signaling was also activated in cardiac myocytes derived from a patient with ACM. These cells produced and secreted abundant inflammatory cytokines under basal conditions, and this was also greatly reduced by Bay 11-7082. CONCLUSIONS:Inflammatory signaling is activated in ACM and drives key features of the disease. Targeting inflammatory pathways may be an effective new mechanism-based therapy for ACM.

SUBMITTER: Chelko SP

PROVIDER: S-EPMC6817418 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Therapeutic Modulation of the Immune Response in Arrhythmogenic Cardiomyopathy.

Chelko Stephen P SP Asimaki Angeliki A Lowenthal Justin J Bueno-Beti Carlos C Bedja Djahida D Scalco Arianna A Amat-Alarcon Nuria N Andersen Peter P Judge Daniel P DP Tung Leslie L Saffitz Jeffrey E JE

Circulation 20190919 18

<h4>Background</h4>Inflammation is a prominent feature of arrhythmogenic cardiomyopathy (ACM), but whether it contributes to the disease phenotype is not known.<h4>Methods</h4>To define the role of inflammation in the pathogenesis of ACM, we characterized nuclear factor-κB signaling in ACM models in vitro and in vivo and in cardiac myocytes from patient induced pluripotent stem cells.<h4>Results</h4>Activation of nuclear factor-κB signaling, indicated by increased expression and nuclear accumula ...[more]

PMID: 31533459

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Project description:Arrhythmogenic cardiomyopathy (AC) is a heart muscle disease clinically characterized by life-threatening ventricular arrhythmias and pathologically by an acquired and progressive dystrophy of the ventricular myocardium with fibro-fatty replacement. Due to an estimated prevalence of 1:2000-1:5000, AC is listed among rare diseases. A familial background consistent with an autosomal-dominant trait of inheritance is present in most of AC patients; recessive variants have also been reported, either or not associated with palmoplantar keratoderma and woolly hair. AC-causing genes mostly encode major components of the cardiac desmosome and up to 50% of AC probands harbor mutations in one of them. Mutations in non-desmosomal genes have been also described in a minority of AC patients, predisposing to the same or an overlapping disease phenotype. Compound/digenic heterozygosity was identified in up to 25% of AC-causing desmosomal gene mutation carriers, in part explaining the phenotypic variability. Abnormal trafficking of intercellular proteins to the intercalated discs of cardiomyocytes and Wnt/beta catenin and Hippo signaling pathways have been implicated in disease pathogenesis.AC is a major cause of sudden death in the young and in athletes. The clinical picture may include a sub-clinical phase; an overt electrical disorder; and right ventricular or biventricular pump failure. Ventricular fibrillation can occur at any stage. Genotype-phenotype correlation studies led to identify biventricular and dominant left ventricular variants, thus supporting the use of the broader term AC.Since there is no "gold standard" to reach the diagnosis of AC, multiple categories of diagnostic information have been combined and the criteria recently updated, to improve diagnostic sensitivity while maintaining specificity. Among diagnostic tools, contrast enhanced cardiac magnetic resonance is playing a major role in detecting left dominant forms of AC, even preceding morpho-functional abnormalities. The main differential diagnoses are idiopathic right ventricular outflow tract tachycardia, myocarditis, sarcoidosis, dilated cardiomyopathy, right ventricular infarction, congenital heart diseases with right ventricular overload and athlete heart. A positive genetic test in the affected AC proband allows early identification of asymptomatic carriers by cascade genetic screening of family members. Risk stratification remains a major clinical challenge and antiarrhythmic drugs, catheter ablation and implantable cardioverter defibrillator are the currently available therapeutic tools. Sport disqualification is life-saving, since effort is a major trigger not only of electrical instability but also of disease onset and progression. We review the current knowledge of this rare cardiomyopathy, suggesting a flowchart for primary care clinicians and geneticists.

Project description:Introduction: We have reported that iPSC-cardiac myocytes from patients with arrhythmogenic cardiomyopathy (ACM) mount an intense innate immune response under basal conditions in vitro. In addition, blocking innate immune signaling via NFκB prevents disease in a mouse model of ACM (Dsg2mut/mut mice). Here, we defined the relative pathogenic roles of immune signaling in cardiac myocytes vs. infiltrating inflammatory cells in Dsg2mut/mut mice. Methods: To define the role of immune signaling in cardiac myocytes, we bred Dsg2mut/mut mice with mice with cardiac myocyte-specific expression of a dominant-negative form of IκBα (DN-IκBα), which prevents nuclear translocation and, thereby, activation of NFκB signaling only in cardiac myocytes. To define the role of inflammatory cells in ACM, we focused on cells expressing C-C motif chemokine receptor-2 (CCR2+ cells), known to mediate adverse cardiac remodeling and fibrosis. We bred Dsg2mut/mut mice with germline deletion of Ccr2 mice (Ccr2-/- mice). We compared phenotypes in Dsg2mut/mut mice with double-mutant Dsg2mut/mut X DN-IκB and Dsg2mut/mut X Ccr2-/- lines. Results: Dsg2mut/mut mice develop marked myocardial fibrosis, reduced LV ejection fraction (EF) and many PVCs. These disease features were all normalized in Dsg2mut/mut X DN-IκB mice. Hearts of Dsg2mut/mut and Dsg2mut/mut X DN-IκB mice contained equal numbers of CD68+ macrophages, but Dsg2mut/mut hearts had many more CCR2+ cells. Cardiac myocyte expression of Tlr4 which activates NFκB, was increased in Dsg2mut/mut mice but not in Dsg2mut/mut X Ccr2-/- mice. Dsg2mut/mut X Ccr2-/- mice showed greatly reduced myocardial fibrosis and PVCs but LV EF was markedly depressed. This suggested that contractile dysfunction in ACM is due not only to loss of muscle but to immune signaling in viable cardiac myocytes as well. To test this hypothesis, we treated Dsg2mut/mut and Dsg2mut/mut X Ccr2-/- mice with the NFκB inhibitor Bay 11-7082. Before treatment, LV EFs were significantly reduced in both groups. Untreated Dsg2mut/mut mice had ongoing deterioration of LV function, whereas treated Dsg2mut/mut mice showed no further disease progression and actually had some improvement in contractile function. However, LV function in treated Dsg2mut/mut X Ccr2-/- mice was virtually normalized. Conclusions: NFκB signaling in cardiac myocytes drives myocardial injury, LV dysfunction and arrhythmias in Dsg2mut/mut mice. It also mobilizes CCR2+ cells to the heart, where they promote myocardial injury and arrhythmias. CCR2+ cells alter gene expression in cardiac myocytes. LV dysfunction in Dsg2mut/mut mice is caused not only by muscle loss but also by negative inotropic effects of inflammation mediated by NFκB in viable cardiac myocytes. These results have obvious implications for ACM patients and suggest that anti-inflammatory therapy may be beneficial even in patients with established disease.

Dataset Information

Therapeutic Modulation of the Immune Response in Arrhythmogenic Cardiomyopathy.

Publications

Therapeutic Modulation of the Immune Response in Arrhythmogenic Cardiomyopathy.

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