Efficacy of Catheter Ablation for Atrial Arrhythmias in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy-A Multicenter Study.

Background: Atrial arrhythmias are present in up to 20% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Catheter ablation (CA) is an effective treatment for atrial arrhythmias in the general population. Data regarding CA for atrial arrhythmias in ARVC are scarce. Objective: To assess the safety and efficacy of CA for atrial arrhythmias in patients with ARVC. Methods: In this international collaborative effort, all patients with a definite diagnosis of ARVC undergoing CA for atrial fibrillation (AF), focal atrial tachycardia (AT), or cavotricuspid isthmus (CTI)-dependent atrial flutter (AFl) were extracted from twelve ARVC registries. Demographic, periprocedural, and long-term arrhythmic outcome data were collected. Results: Thirty-seven patients were enrolled in the study (age 50.2 ± 16.6 years, male 84%, CHA2DS2VASc 1 (1,2), HAS-BLED 0 (0-2)). The arrhythmia leading to CA was AF in 23 (62%), focal left AT in 5 (14%), and CTI-dependent AFl in 9 (24%). Acute procedural success was achieved in all procedures but one (n = 1 focal left AT; 97% acute success). The median follow-up period was 27 (13-67) months, and 96%, 74%, and 61% of patients undergoing AF ablation were free from any atrial arrhythmia recurrence after a single procedure at 6 months, 12 months, and last follow-up, respectively. After focal AT ablation, freedom from atrial arrhythmia recurrence was 80%, 80%, and 60% at 6 months, 12 months, and last follow-up, respectively. All patients undergoing CTI ablation were free from atrial arrhythmia recurrences at 6 months, with 89% single-procedural arrhythmic freedom at last follow-up. One major complication (2.7%; PV stenosis requiring PV stenting) occurred. Conclusions: CA is safe and effective in managing atrial arrhythmias in patients with ARVC, with success rates comparable to the general population.

Intraventricular flow visualization in different heart failure stages with blood pump support in a mock circulatory loop.

The intraventricular blood flow changed by blood pump flow dynamics may correlate with thrombosis and ventricular suction. The flow velocity, distribution of streamlines, vorticity, and standard deviation of velocity inside a left ventricle failing to different extents throughout the cardiac cycle when supported by an axial blood pump were measured by particle image velocimetry (PIV) in this study. The results show slower and static flow velocities existed in the central region of the left ventricle near the mitral valve and aortic valve and that were not sensitive to left ventricular (LV) failure degree or LV pressure. Strong vorticity located near the inner LV wall around the LV apex and the blood pump inlet was not sensitive to LV failure degree or LV pressure. Higher standard deviation of the blood velocity at the blood pump inlet decreased with increasing LV failure degree, whereas the standard deviation of the velocity near the atrium increased with increasing intraventricular pressure. The experimental results demonstrated that the risk of thrombosis inside the failing left ventricle is not related to heart failure degree. The "washout" performance of the strong vorticity near the inner LV wall could reduce the thrombotic potential inside the left ventricle and was not related to heart failure degree. The vorticity near the aortic valve was sensitive to LV failure degree but not to LV pressure. We concluded that the risk of blood damage caused by adverse flow inside the left ventricle decreased with increasing LV pressure.

Cadherin 2-Related Arrhythmogenic Cardiomyopathy: Prevalence and Clinical Features.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiac disease characterized by fibrofatty replacement of the right and left ventricle, often causing ventricular dysfunction and life-threatening arrhythmias. Variants in desmosomal genes account for up to 60% of cases. Our objective was to establish the prevalence and clinical features of ACM stemming from pathogenic variants in the nondesmosomal cadherin 2 (CDH2), a novel genetic substrate of ACM. METHODS: A cohort of 500 unrelated patients with a definite diagnosis of ACM and no disease-causing variants in the main ACM genes was assembled. Genetic screening of CDH2 was performed through next-generation or Sanger sequencing. Whenever possible, cascade screening was initiated in the families of CDH2-positive probands, and clinical evaluation was performed. RESULTS: Genetic screening of CDH2 led to the identification of 7 rare variants: 5, identified in 6 probands, were classified as pathogenic or likely pathogenic. The previously established p.D407N pathogenic variant was detected in 2 additional probands. Probands and family members with pathogenic/likely pathogenic variants in CDH2 were clinically evaluated, and along with previously published cases, altogether contributed to the identification of gene-specific features (13 cases from this cohort and 11 previously published, for a total of 9 probands and 15 family members). Ventricular arrhythmic events occurred in most CDH2-positive subjects (20/24, 83%), while the occurrence of heart failure was rare (2/24, 8.3%). Among probands, sustained ventricular tachycardia and sudden cardiac death occurred in 5/9 (56%). CONCLUSIONS: In this worldwide cohort of previously genotype-negative ACM patients, the prevalence of probands with CDH2 pathogenic/likely pathogenic variants was 1.2% (6/500). Our data show that this cohort of CDH2-ACM patients has a high incidence of ventricular arrhythmias, while evolution toward heart failure is rare.

Inhibition of Bcl2L12 Attenuates Eosinophilia-Related Inflammation in the Heart.

Background: The eosinophilic inflammation plays a critical role in myocarditis (Mcd); its underlying mechanism remains to be further elucidated. This study aims to investigate the role of Bcl2-like protein 12 (Bcl2L12) in inducing the defects of apoptosis in eosinophils (Eos) of the heart tissues. Methods: Human explant heart samples were collected. Eosinophilia and myocarditis (Mcd)-like inflammation were induced in the mouse heart by immunizing with murine cardiac α-myosin heavy chain (MyHCα) peptides. Results: Markedly more Eos were observed in heart tissues from patients with Mcd than those from patients with dilated cardiomyopathy. Eos isolated from Mcd hearts showed the signs of apoptosis defects. The Eo counts in the Mcd heart tissues were positively correlated with the Bcl2L12 expression in Eos isolated from the heart tissues. Exposure to interleukin 5 in the culture induced the expression of Bcl2L12 in Eos. Bcl2L12 bound c-Myc, the transcription factor of Fas ligand (FasL), to prevent c-Myc from binding to the FasL promoter, to restrict the FasL gene transcription in Eos. Inhibition of Bcl2L12 prevented the induction of eosinophilia and Mcd-like inflammation in the mouse heart. Conclusions: The Bcl2L12 expression contributes to apoptosis defects in Eos of the Mcd heart. Blocking Bcl2L12 prevents the eosinophilia induction and alleviates Mcd-like inflammation in mice.

House Dust Mite Specific Antibodies induce Neutrophilic Inflammation in the Heart.

Rationale: Inflammatory heart disorders are among the causes of human death. The causative factors of heart inflammation are to be further elucidated. House dust mite (HDM)-derived protein antigens are involved in the pathogenesis of many human diseases. This study aims to investigate the role of HDM-specific autoantibodies in the pathogenesis of heart inflammation. Methods: Human heart tissue samples were obtained from surgically removed hearts in heart transplantation. The interaction of the heart tissues with HDM-specific antibodies was assessed by pertinent immune analysis. The role of HDM-specific autoantibodies in the induction of heart inflammation was assessed with a murine model. Results: HDM-specific IgG (mIgG) was detected in the serum of patients with myocarditis (Mcd); the mIgG titers were positively correlated with the neutrophil counts in the heart tissues. The mIgG specifically bound to keratin-10 (KRT10) in heart vascular endothelial cells and the heart tissue protein extracts. The amounts of C3a, C5a and C5b-9 were increased in the mouse heart tissues after exposing to mIgG. In the presence of the complement-containing serum, mIgG bound cardiovascular epithelial monolayers to impair the barrier functions. Administration of mIgG or HDM induced the Mcd-like inflammation in the heart, in which neutrophils were the dominant cellular components in the infiltration of inflammatory cells. Conclusions: Mcd patients with neutrophilic inflammation in the heart had higher serum levels of mIgG. The mIgG bound heart endothelial cells to impair the endothelial barrier functions and induce neutrophilic inflammation in the heart.

Elevated plasma ß-hydroxybutyrate predicts adverse outcomes and disease progression in patients with arrhythmogenic cardiomyopathy.

Sudden death could be the first symptom of patients with arrhythmogenic cardiomyopathy (AC), a disease for which clinical indicators predicting adverse progression remain lacking. Recent findings suggest that metabolic dysregulation is present in AC. We performed this study to identify metabolic indicators that predicted major adverse cardiac events (MACEs) in patients with AC and their relatives. Comparing explanted hearts from patients with AC and healthy donors, we identified deregulated metabolic pathways using quantitative proteomics. Right ventricles (RVs) from patients with AC displayed elevated ketone metabolic enzymes, OXCT1 and HMGCS2, suggesting higher ketone metabolism in AC RVs. Analysis of matched coronary artery and sinus plasma suggested potential ketone body synthesis at early-stage AC, which was validated using patient-derived induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) in vitro. Targeted metabolomics analysis in RVs from end-stage AC revealed a "burned-out" state, with predominant medium-chain fatty acid rather than ketone body utilization. In an independent validation cohort, 65 probands with mostly non-heart failure manifestations of AC had higher plasma ß-hydroxybutyrate (ß-OHB) than 62 healthy volunteers (P < 0.001). Probands with AC with MACE had higher ß-OHB than those without MACE (P < 0.001). Among 94 relatives of probands, higher plasma ß-OHB distinguished 25 relatives having suspected AC from nonaffected relatives. This study demonstrates that elevated plasma ß-OHB predicts MACE in probands and disease progression in patients with AC and their clinically asymptomatic relatives.

Hemodynamic effects of myocardial bridging in patients with hypertrophic cardiomyopathy.

Myocardial bridging (MB) is linked to angina and myocardial ischemia and may lead to sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). However, it remains unclear how MB affect the coronary blood flow in HCM patients. The aim of this study was to assess the effects of MB on coronary hemodynamics in HCM patients. Fifteen patients with MB (7 HCM and 8 non-HCM controls) in their left anterior descending (LAD) coronary artery were chosen. Transient computational fluid dynamics (CFD) simulations were conducted in anatomically realistic models of diseased (with MB) and virtually healthy (without MB) LAD from these patients, reconstructed from biplane angiograms. Our CFD simulation results demonstrated that dynamic compression of MB led to diastolic flow disturbances and could significantly reduce the coronary flow in HCM patients as compared with non-HCM group (P < 0.01). The pressure drop coefficient was remarkably higher (P < 0.05) in HCM patients. The flow rate change is strongly correlated with both upstream Reynolds number and MB compression ratio, while the MB length has less impact on coronary flow. The hemodynamic results and clinical outcomes revealed that HCM patients with an MB compression ratio higher than 65% required a surgical intervention. In conclusion, the transient MB compression can significantly alter the diastolic flow pattern and wall shear stress distribution in HCM patients. HCM patients with severe MB may need a surgical intervention.NEW & NOTEWORTHY In this study, the hemodynamic significance of myocardial bridging (MB) in patients with hypertrophic cardiomyopathy (HCM) was investigated to provide valuable information for surgical decision-making. Our results illustrated that the transient MB compression led to complex flow patterns, which can significantly alter the diastolic flow and wall shear stress distribution. The hemodynamic results and clinical outcomes demonstrated that patients with HCM and an MB compression ratio higher than 65% required a surgical intervention.

Outcome and Pathological Characteristics of Primary Malignant Cardiac Tumors.

The literature on malignant cardiac tumors is relatively limited because they are rare, especially among the Chinese population. We analyzed 14 patients diagnosed with malignant cardiac tumors in Fuwai Hospital and present the results of surgical treatments on the tumors. The mean age at tumor diagnosis was 47 years in a male-dominated cohort. There was a high frequency of pericardial effusion and coronary artery involvement in our group. We compared the survival times of patients who received different treatments and found that surgery improved prognosis of tumors, especially for patients who underwent orthotopic heart transplantation.

A high-density genetic map and QTL mapping of leaf traits and glucosinolates in Barbarea vulgaris.

BACKGROUND: Barbarea vulgaris is a wild cruciferous plant and include two distinct types: the G- and P-types named after their glabrous and pubescent leaves, respectively. The types differ significantly in resistance to a range of insects and diseases as well as glucosinolates and other chemical defenses. A high-density linkage map was needed for further progress to be made in the molecular research of this plant. RESULTS: We performed restriction site-associated DNA sequencing (RAD-Seq) on an F2 population generated from G- and P-type B. vulgaris. A total of 1545 SNP markers were mapped and ordered in eight linkage groups, which represents the highest density linkage map to date for the crucifer tribe Cardamineae. A total of 722 previously published genome contigs (50.2 Mb, 30% of the total length) can be anchored to this high density genetic map, an improvement compared to a previously published map (431 anchored contigs, 38.7 Mb, 23% of the assembly genome). Most of these (572 contigs, 31.2 Mb) were newly anchored to the map, representing a significant improvement. On the basis of the present high-density genetic map, 37 QTL were detected for eleven traits, each QTL explaining 2.9-71.3% of the phenotype variation. QTL of glucosinolates, leaf size and color traits were in most cases overlapping, possibly implying a functional connection. CONCLUSIONS: This high-density linkage map and the QTL obtained in this study will be useful for further understanding of the genetic of the B. vulgaris and molecular basis of these traits, many of which are shared in the related crop watercress.

A modified method for isolation of human cardiomyocytes to model cardiac diseases.

BACKGROUND: Cardiomyocytes derived from animals and induced pluripotent stem cells (iPSCs) are two main cellular models to study cardiovascular diseases, however, neither provides precise modeling of the response of mature human cardiomyocytes to disease or stress conditions. Therefore, there are emerging needs for finding an optimized primary human cardiomyocytes isolation method to provide a bona fide cellular model. METHODS AND RESULTS: Previous established protocols for the isolation of primary human cardiomyocytes are limited in their application due to relatively low cell yield and the requirement of tissue integrity. Here, we developed a novel, simplified method to isolate human cardiomyocytes robustly with improved viability from tissue slicing. Isolated cardiomyocytes showed intact morphology, retained contractility, ion flux, calcium handling, and responses to neurohormonal stimulation. In addition, we assessed the metabolic status of cardiomyocytes from different health conditions. CONCLUSION: We present a novel, simplified method for isolation of viable cardiomyocytes from human tissue.

Comprehensive Myocardial Proteogenomics Profiling Reveals C/EBPα as the Key Factor in the Lipid Storage of ARVC.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is hereditary cardiomyopathy characterized by the fibro-fatty replacement of the myocardium. A small number of noncomprehensive profiling studies based on human cardiac tissues have been conducted and reported; consequently, ARVC's gene expression pattern characteristics remain largely undocumented. Our study applies large-scaled, quantitative proteomics based on TMT-labeled LC-MS/MS to analyze the left and right ventricular myocardium of four ARVC and four DCM explanted hearts to compare them with normal hearts. Our objective is to reveal the characteristic proteome pattern in ARVC compared with DCM as well as nondiseased heart. We also conducted the RNA sequencing of 10 right ventricles from ARVC hearts paired with four nondiseased donor hearts to validate the proteome results. In a manner similar to that of the well-defined DCM heart failure model, the ARVC model demonstrates the downregulation of mitochondrial function proteins and the effects of many heart failure regulators such as TGFB, RICTOR, and KDM5A. In addition, the inflammatory signaling, especially the complement system, was activated much more severely in ARVC than in DCM. Our most significant discovery was the lipid metabolism reprogramming of both ARVC ventricles in accordance with the upregulation of lipogenesis factors such as FABP4 and FASN. We identified the key upstream regulator of lipogenesis as C/EBPα. Transcriptome profiling verified the consistency with proteome alterations. This comprehensive proteogenomics profiling study reveals that an activation of C/EBPα, along with the upregulation of its lipogenesis targets, accounts for lipid storage and acts as a hallmark of ARVC.

Insulin-like growth factor-2 enhances functions of antigen (Ag)-specific regulatory B cells.

Regulatory B cells (Bregs) are important in immune regulation. The factors that regulate Breg functions are less clear. Insulin-like growth factor 2 (IGF2) is capable of inducing hematopoietic stem cell differentiation. This study aimed to investigate the role of IGF2 in the development of Bregs and the enhancement of their function. In this study, the expression of IGF1 receptor (IGF1R) and IGF2R in ovalbumin (OVA)-specific B cells (OVAsBCs) was assessed by real time RT-PCR and Western blotting. The release of interleukin (IL)-10 from OVAsBCs and OVAsBC proliferation were assessed by enzyme-linked immunoassay and proliferation assay. The role of IGF2 in enhancing the function of OVAsBCs was tested with an intestinal allergic inflammation mouse model. The results showed that OVAsBCs expressed high levels of IGF2R. Exposure to both IGF2 and a specific antigen (Ag), OVA, markedly enhanced the expression of IL-10 in OVAsBCs as well as enhanced the IL-10(+) OVAsBC proliferation. The concurrent exposure to IGF2 and specific Ag markedly induced the IL-10 promoter DNA demethylation via activating the STAT5 pathway. IGF2 also enhanced both the OVAsBC proliferation in vivo and the effect of Ag-specific immunotherapy on inhibiting allergic inflammation in the intestine. We conclude that OVAsBCs express high levels of IGF2R and that IGF2 increases the expression of IL-10 in OVAsBCs and enhances OVAsBC proliferation and the inhibitory effect on allergic inflammation.

Insulin-like growth factor 2 enhances regulatory T-cell functions and suppresses food allergy in an experimental model.

BACKGROUND: The functions of regulatory T (Treg) cells are important in immunity, and the regulatory mechanisms of Treg cell activities are not fully understood yet. OBJECTIVES: We sought to investigate the role of insulin-like growth factor (IGF) 2 in the upregulation of Treg cell function. METHODS: The expression of insulin-like growth factor 2 receptor (IGF2R) on T cells was assessed by using flow cytometry. Treg cell functions were evaluated by assessing the suppressor effect on proliferation of other effector T (Teff) cells. The effect of IGF2 on regulating Treg cell functions were evaluated with a cell-culture model and a food allergy mouse model. RESULTS: Expression of IGF2R was observed in more than 90% of murine and human Treg cells but in less than 10% of effector CD4(+) T cells. Activation of IGF2R and T-cell receptor induced marked Treg cell proliferation and release of TGF-ß from Treg cells, which enhanced Treg cell immune suppressor effects on other Teff cell activities and allergic inflammation in the intestine. CONCLUSIONS: Activation of IGF2R enhances Treg cell functions in suppressing other Teff cell activities and inhibiting allergic inflammation in the intestine.

Mast cell-derived serine proteinase regulates T helper 2 polarization.

Although mast cells play a critical role in allergic reactions, the cells are also involved in the protective immunity in the body. This study aims to investigate the role of mast cells in immune regulation during aberrant T helper (Th)2 responses. In this study, an adoptive antigen-specific Th2 response model was established with mast cell-deficient mice to test the role of mast cell in the immune regulation. Cell culture was employed to test the role of mast cells in the modulation of the expression of B cell lymphoma 6 protein (Bcl-6) in Th2 cells. The results showed that after adoptive transfer with immune cells, the mast cell-deficient mice showed stronger Th2 pattern responses in the intestine than that in the mast cell-sufficient mice. Mast cell-derived mouse mast cell protease-6 increased the expression of Bcl-6 in Th2 cells. Bcl-6 inhibited the expression of GATA-3 in Th2 cells, subsequently, forkhead box P3 was increased and the Th2 cytokines were reduced in the cells; the cells thus showed the immune regulatory properties similar to regulatory T cells. We conclude that bedsides initiating immune inflammation, mast cells also contribute to the immune regulation on Th2 polarization.

Dynamics of interstitial calcium in rat myocardial ischemia reperfusion injury in vivo.

Intracellular calcium overload is a key factor for myocardial ischemia reperfusion injury (IR). However, there was no report for interstitial calcium concentration dynamics. We investigated the interstitial calcium dynamics in rat myocardial IR model in vivo. A microdialysis system was involved, and the time delay of the system and recovery time was introduced and tested with a fluids switching method. Twelve SD rats were divided into IR or control group. Myocardial IR was induced by ligating (20 min) then releasing (60 min) the suture underlying left anterior descending branch. Mycrodialyisis probe was implanted into the left ventricular myocardium perfusion area for occlusion. Dialysate samples were collected every 10 min. Dialysate calcium concentration was detected with an atomic absorption spectrophotometer. Recovery time for the microdialysis system was 20 min, and recovery rate was 16%. Dialysate calcium concentration showed no changes during ischemia, descended immediately after reperfusion, reached the lowest level (67% of baseline value) 20 min after reperfusion, then escalated slowly. Recovery time was an important parameter for mycrodialysis technique, and it should not be neglected and needed to be tested. Our data suggest that interstitial calcium concentration in rats with myocardial IR in vivo kept steady in ischemia, descended rapidly at the initial reperfusion, then rebounded slowly. In conclusion, we introduced the concept of recovery time for microdialysis and provided a simple testing method.

Corticotropin releasing hormone activates CD14+ cells to induce endothelial barrier dysfunction.

Endothelial barrier dysfunction is associated with the pathogenesis of a number of disorders in the body, but the aetiology is unclear. We have investigated the mechanism of the psychological stress mediator, corticotropin releasing hormone (CRH), on compromising the endothelial barrier function. Human endothelial cell line, Hmvec cells, was cultured in monolayers as a model of endothelial barrier. Human peripheral CD14+ cells were collected to be used as effector immune cells. The transepithelial resistance (TER) and permeability of horseradish peroxidase (HRP) were used as indicators of endothelial barrier function. Apoptosis in Hmvec cells were analysed by flow cytometry. Human CD14+ cells expressed both receptors (R) of CRH, the CRH-R1 and CRH-R2. Exposure to CRH induced CD14+ cells to release tumour necrosis factor (TNF)-α. CRH-activated CD14+ cells decreased TER and increased the permeability to HRP in co-cultured Hmvec monolayers. Co-culture with CRH-activated CD14+ cells increased the apoptosis in Hmvec cells. We conclude that CRH can activate CD14+ cells to produce TNF-α and compromise endothelial barrier function by inducing apoptosis of the endothelial cells.

ASYMMETRIC LEAVES2 gene, a member of LOB/AS2 family of Arabidopsis thaliana, causes an abaxializing leaves in transgenic cockscomb.

The leaf primordium derives from the peripheral zone of shoot apical meristem. During the formation of leaf primordia, they need to establish the proximodistal, mediolateral, and ab/adaxial axes. Among these axes, the ab/adaxial axis might be the most important. ASYMMETRIC LEAVES2 (AS2) gene is a member of AS2/LATERAL ORGAN BOUNDARY (LOB) family of Arabidopsis thaliana. In this work, we transformed 35S:AS2 transgene constructs to cockscomb (Celosia cristata) via Agrobacterium tumefaciens. All primary transformants subsequently obtained were placed into phenotypic categories and self-pollinated. As a whole, a total of 44 T1 35S:AS2 cockscomb plants obtained were grouped into two major categories: (I) slightly wrinkled leaves (28/44), (II) extremely curved leaves (16/44), on the basis of their leaf phenotypes. Furthermore, we characterized the anatomical features of these malformed leaves; and found the transformation of adaxial cell types into abaxial cell ones. A series of data suggest that AS2 might be involved in the determination of abaxial polarity in cockscomb plants. However, a few research teams have reported that AS2 might be involved in the determination of adaxial polarity in leaf primodia of Arabidopsis thaliana. These data above indicate that the roles of the same ab/adaxial determinant might differ between distinct species. At last, the different function of AS2 in distinct species was discussed.