Introduction: Arrhythmogenic cardiomyopathy (ACM) is hereditary cardiomyopathy caused by pathogenic variants (mutations) in genes encoding the intercalated disc (ID), particularly desmosome proteins. ACM caused by mutations in the DSP gene encoding desmoplakin (DSP) is characterized by the prominence of cell death, myocardial fibrosis, and inflammation, and is referred to as desmoplakin cardiomyopathy.

Aim: The aim of this article was to gain insight into the pathogenesis of DSP cardiomyopathy.

Methods and Results: The Dsp gene was exclusively deleted in cardiac myocytes using tamoxifen-inducible MerCreMer (Myh6-Mcm^Tam) and floxed Dsp (Dsp^F/F) mice (Myh6-Mcm^Tam:Dsp^F/F). Recombination was induced upon subcutaneous injection of tamoxifen (30 mg/kg/d) for 5 days starting post-natal day 14. Survival was analyzed by Kaplan-Meier plots, cardiac function by echocardiography, arrhythmias by rhythm monitoring, and gene expression by RNA-Seq, immunoblotting, and immunofluorescence techniques. Cell death was analyzed by the TUNEL assay and the expression levels of specific markers were by RT-PCR and immunoblotting. Myocardial fibrosis was assessed by picrosirius red staining of the myocardial sections, RT-PCR, and immunoblotting. The Myh6-Mcm^Tam:Dsp^F/F mice showed extensive molecular remodeling of the IDs and the differential expression of ~10,000 genes, which predicted activation of KDM5A, IRFs, and NFκB and suppression of PPARGC1A and RB1, among others in the DSP-deficient myocytes. Gene set enrichment analysis predicted activation of the TNFα/NFκB pathway, inflammation, cell death programs, and fibrosis. Analysis of cell death markers indicated PANoptosis, comprised of apoptosis (increased CASP3, CASP8, BAD and reduced BCL2), necroptosis (increased RIPK1, RIPK3, and MLKL), and pyroptosis (increased GSDMD and ASC or PYCARD) in the DSP-deficient myocytes. Transcript levels of the pro-inflammatory and pro-fibrotic genes were increased and myocardial fibrosis comprised ~25% of the myocardium in the DSP-deficient hearts. The Myh6-Mcm^Tam:Dsp^F/F mice showed severe cardiac systolic dysfunction and ventricular arrhythmias, and died prematurely with a median survival rate of ~2 months.

Conclusion: The findings identify PANoptosis as a prominent phenotypic feature of DSP cardiomyopathy and set the stage for delineating the specific molecular mechanisms involved in its pathogenesis. The model also provides the opportunity to test the effects of pharmacological and genetic interventions on myocardial fibrosis and cell death.

One sentence summary: Post-natal homozygous deletion of the Dsp gene leads to fulminant PANoptosis and severe myocardial fibrosis, cardiac dysfunction, arrhythmias, and premature death in mice.

Introduction: The TNNI3 gene encodes the protein of cardiac troponin I (cTnI), which is an inhibitory subunit of sarcomeres. Mutations in this gene account for 3% of hypertrophic cardiomyopathy (HCM) and the molecular mechanism is complex. Recently, lipid metabolism has been revealed to be involved in HCM.

Aim: The purpose of this work is to identify whether the pathological mechanism of the hotspot mutation TNNI3 p.R186Q in HCM is related to abnormal lipid metabolism.

Methods and Results: A knock-in (KI) mouse model carrying the Tnni3 p.R186Q homozygous mutation (Tnni3^R186Q/R186Q) was novelty generated by CRISPR/Cas9 technology and successfully constructed a typical phenotype of cardiac-myopathy. Likewise, neonatal rat cardiomyocytes (NRCMs) transfected with a mutant plasmid with the TNNI3 p.R186Q mutation showed the same phenomenon. In-depth experiments on related functions and molecular mechanisms were conducted, and Tnni3^R186Q/R186Q mice exhibited abnormal fatty acid metabolism, which was induced by the activation of epidermal growth factor receptor (EGFR)-dependent high expression of fatty acid synthase (FASN) in vivo and in vitro. Specifically, the direct binding of EGFR and cTnI was destroyed by TNNI3 p.R186Q mutation, as observed through bioinformatics, Co-IP and GST-pull down analysis.

Conclusion: In the present study, we successfully engineered Tnni3^R186Q/R186Q mice with the typical phenotype of myocardial hypertrophy. We demonstrated that the TNNI3 p.R186Q mutation could induce HCM by the dissociation of EGFR and cTnI, which further led to EGFR-dependent increased expression of FASN and abnormal lipid metabolism.

Coronary atherosclerosis is a leading cause of death as a result of coronary thrombosis and acute myocardial infarction. Drug-eluting stents (DES) have dramatically improved the treatment of coronary artery stenosis. However, stent thrombosis (ST) and in-stent-restenosis (ISR) have remained a vexing limitation of the DES. After DES implantation, despite taking dual antiplatelet (DAPT) therapy, very late ST results in myocardial infarction and death. This occurs regardless of the type of polymer or antiproliferative agent used in the contemporary DES. Such adverse events occur at a rate of approximately 2% to 3% per year after the first year, which have been attributed to strut fractures, loss of vessel compliance, and neoatherosclerosis. Bioresorbable scaffolds (BRS) have been introduced to overcome the above shortfalls and to a “leave nothing behind” approach. While BRS are novel and interesting, the initial experience with BRS was hampered by the increased rate of thrombosis compared with DES. Accordingly, in this review, we summarized underlying mechanisms leading to BRS failure and provided insights into optimizing BRS deployment with intravascular imaging. In addition, we outlined the perspectives of new generations of BRS with thinner struts and new designs as well as alternative materials to improve outcomes.

This review provides a holistic perspective on the bi-directional relationship between cardiac mitochondrial dysfunction and myocardial structural remodeling in the context of metabolic heart disease, natural cardiac aging, and heart failure. First, a review of the physiologic and molecular drivers of cardiac mitochondrial dysfunction across a range of increasingly prevalent conditions such as metabolic syndrome and cardiac aging is presented, followed by a general review of the mechanisms of mitochondrial quality control (QC) in the heart. Several important mechanisms by which cardiac mitochondrial dysfunction triggers or contributes to structural remodeling of the heart are discussed: accumulated metabolic byproducts, oxidative damage, impaired mitochondrial QC, and mitochondrial-mediated cell death identified as substantial mechanistic contributors to cardiac structural remodeling such as hypertrophy and myocardial fibrosis. Subsequently, the less studied but nevertheless important reverse relationship is explored: the mechanisms by which cardiac structural remodeling feeds back to further alter mitochondrial bioenergetic function. We then provide a condensed pathogenesis of several increasingly important clinical conditions in which these relationships are central: diabetic cardiomyopathy, age-associated declines in cardiac function, and the progression to heart failure, with or without preserved ejection fraction. Finally, we identify promising therapeutic opportunities targeting mitochondrial function in these conditions.

Introduction: More than 100 genes are reportedly associated with dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). However, the situation that many genes lack of reassessment in a large population hinders the interpretations of these genes in genetic diagnostic testing. Moreover, limited genetic data for cardiomyopathy in Chinese patients was reported.

Aim: Therefore, here we reassessed an estimated 500 putative genes in the Chinese Han population by whole exome sequencing (WES) to describe the landscape of variants in these genes and to confirm their genetic contribution to DCM and HCM.

Methods and Results: WES was performed in 1059 DCM patients, 1175 HCM patients and 514 controls. Approximately 500 candidate genes were selected for evaluation. Truncating variants of TTN and MYBPC3 were the most burdensome for both groups. Gene-based association tests identified 35 and 35 genes associated with DCM and HCM, respectively. Except for the known genes of cardiomyopathy, the top three genes associated with DCM were MUC16, KMT2C, and FBN1, while the top three genes associated with HCM were KMT2C, RYR2, and SCN5A. After filtering for pathogenicity, FBN1 is still significantly associated with DCM and SCN5A and RYR2 remains significantly enriched in HCM patients. However, after adjustment, only TTN with DCM and MYBPC3 and MYH7 with HCM remains significant.

Conclusion: We described the genetic landscape of Chinese patients with DCM and HCM and developed a website (www.cardioexome.cn) to enable open access to this information. Furthermore, the gene-based association test confirmed the contribution of TTN to DCM and MYBPC3 and MYH7 to HCM in Chinese Han. In addition, the website, www.cardioexome.cn, was developed to store these sequencing results.