Total Glucosides of Paeony Ameliorate Myocardial Injury in Chronic Heart Failure Rats by Suppressing PARP-1

Total glucosides of paeony (TGP) have a potential protective effect on chronic heart failure (CHF) rats, but the mechanism remains unclear. PARP inhibition prevents the decrease in myocardial contractility. Therefore, we aim to investigate the effects and mechanisms of TGP on CHF and the role of PARP-1 in CHF. Left anterior descending ligation rats and adriamycin-treated H9C9 cells were used as CHF models, and captopril as a positive control for in vivo experiments. We found that TGP alleviated myocardial remodeling and improved cardiac morphology and function. TGP also reduced myocardial apoptosis and autophagy, decreased inflammatory factor release, and inhibited the PARP-1 and NF-κB proteins. Through cell transfection, we found that PAPR-1 knockdown inhibited NF-κB nuclear translocation. Additionally, TGP inhibited apoptosis, autophagy, and inflammation in CHF cells, while PARP-1 overexpression partially antagonized them. In conclusion, TGP has the potential to improve CHF and PARP-1 may be a potential target.

G protein-coupled receptor kinase 5 (GRK5) contributes to impaired cardiac function and immune cell recruitment in post-ischemic heart failure

AIMS

Myocardial infarction (MI) is the most common cause of heart failure (HF) worldwide. G protein-coupled receptor kinase 5 (GRK5) is upregulated in failing human myocardium and promotes maladaptive cardiac hypertrophy in animal models. However, the role of GRK5 in ischemic heart disease is still unknown. In this study, we evaluated whether myocardial GRK5 plays a critical role post-MI in mice and included the examination of specific cardiac immune and inflammatory responses.

METHODS AND RESULTS

Cardiomyocyte-specific GRK5 overexpressing transgenic mice (TgGRK5) and non-transgenic littermate control (NLC) mice as well as cardiomyocyte-specific GRK5 knockout mice (GRK5cKO) and wild type (WT) were subjected to MI and, functional as well as structural changes together with outcomes were studied. TgGRK5 post-MI mice showed decreased cardiac function, augmented left ventricular dimension and decreased survival rate compared to NLC post-MI mice. Cardiac hypertrophy and fibrosis as well as fetal gene expression were increased post-MI in TgGRK5 compared to NLC mice. In TgGRK5 mice, GRK5 elevation produced immuno-regulators that contributed to the elevated and long-lasting leukocyte recruitment into the injured heart and ultimately to chronic cardiac inflammation. We found an increased presence of pro-inflammatory neutrophils and macrophages as well as neutrophils, macrophages and T-lymphocytes at 4-days and 8-weeks respectively post-MI in TgGRK5 hearts. Conversely, GRK5cKO mice were protected from ischemic injury and showed reduced early immune cell recruitment (predominantly monocytes) to the heart, improved contractility and reduced mortality compared to WT post-MI mice. Interestingly, cardiomyocyte-specific GRK2 transgenic mice did not share the same phenotype of TgGRK5 mice and did not have increased cardiac leukocyte migration and cytokine or chemokine production post-MI.

CONCLUSIONS

Our study shows that myocyte GRK5 has a crucial and GRK-selective role on the regulation of leucocyte infiltration into the heart, cardiac function and survival in a murine model of post-ischemic HF, supporting GRK5 inhibition as a therapeutic target for HF.

Protective role of emodin in rats with post-myocardial infarction heart failure and influence on extracellular signal-regulated kinase pathway

We aimed to explore the effects of emodin on the energy metabolism of myocardial cells in rats with post-myocardial infarction (MI) heart failure (HF) and the extracellular signal-regulated kinase (ERK) pathway. The model of MI was established by ligation of the left anterior descending branch. After 4 weeks, the rats with left ventricular ejection fraction (LVEF) of ≤45% were used aspost-MI HF model animals and randomly divided into model, low-dose, middle-dose, high-dose and control groups (n=10). Low-, middle- and high-dose groups were gavaged with 20 mg/kg, 40 mg/kg and 60 mg/kg emodin daily, respectively. After administration for 14 d, the changes in LVEF, left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD) and interventricular septum thickness (IVS) were analyzed. The apoptosis rate of myocardial cells was detected by TUNEL staining. The levels of serum cardiac troponin I (cTnI) and peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1) were determined using ELISA, and the expressions of mitochondrial respiratory chain complex I protein and phosphorylated-ERK (p-ERK) in myocardial tissues were determined by Western blotting.  Compared with model group, LVEDD, LVESD, apoptosis rate of myocardial cells, levels of serum cTnI and PGC-1, and expressions of complex I and p-ERK in myocardial tissues significantly decreased, while LVEF and IVS increased in low-dose, middle-dose, high-dose and control groups (P<0.05). The changes in the above indices were significantly dependent on the dose of emodin (P<0.05).Emodin can significantly relieve post-MI HF, reduce the apoptosis rate of myocardial tissues, and ameliorate the cardiac function of rats.

Ubiquitin ligase Wwp1 gene deletion attenuates diastolic dysfunction in pressure-overload hypertrophy

Heart failure with a preserved left ventricular (LV) ejection fraction (HFpEF) often arises from a prolonged LV pressure overload (LVPO) and accompanied by abnormal extracellular matrix (ECM) accumulation. The E3 ubiquitin ligase WWP1 is a fundamental determinant ECM turnover. We tested the hypothesis that genetic ablation of Wwp1 would alter the progression of LVPO-induced HFpEF. LV echocardiography in mice with global Wwp1 deletion (n = 23; Wwp1-/-) was performed at 12 wk of age (baseline) and then at 2 and 4 wk following LVPO (transverse aortic banding) or surgery without LVPO induction. Age-matched wild-type mice (Wwp1+/+; n = 23) underwent identical protocols. LV EF remained constant and unchanged with LVPO and LV mass increased in both groups but was lower in the Wwp1-/- mice. With LVPO, the E/A ratio, an index of LV filling, was 3.97 ± 0.46 in Wwp1+/+ but was 1.73 ± 0.19 in the Wwp1-/- group (P < 0.05). At the transcriptional level, mRNA for fibrillar collagens (types I and III) decreased by approximately 50% in Wwp1-/- compared with the Wwp1+/+ group at 4 wk post-LVPO (P < 0.05) and was paralleled by a similar difference in LV fibrillar collagen content as measured by histochemistry. Moreover, mRNA levels for determinants favoring ECM accumulation, such as transforming growth factor (TGF), increased with LVPO, but were lower in the Wwp1-/- group. The absence of Wwp1 reduced the development of left ventricular hypertrophy and subsequent progression to HFpEF. Modulating the WWP1 pathway could be a therapeutic target to alter the natural history of HFpEF.NEW & NOTEWORTHY Heart failure with a preserved left ventricular (LV) ejection fraction (HFpEF) often arises from a prolonged LV pressure overload (LVPO) and is accompanied by abnormal extracellular matrix (ECM) accumulation. It is now recognized that the ECM is a dynamic entity that is regulated at multiple post-transcriptional levels, including the E3 ubiquitin ligases, such as WWP1. In the present study, WWP1 deletion in the context of an LVPO stimulus reduced functional indices of HFpEF progression and determinants of ECM remodeling.

Relevance of Neutrophil Neprilysin in Heart Failure

Significant expression of neprilysin (NEP) is found on neutrophils, which present the transmembrane integer form of the enzyme. This study aimed to investigate the relationship of neutrophil transmembrane neprilysin (mNEP) with disease severity, adverse remodeling, and outcome in HFrEF. In total, 228 HFrEF, 30 HFpEF patients, and 43 controls were enrolled. Neutrophil mNEP was measured by flow-cytometry. NEP activity in plasma and blood cells was determined for a subset of HFrEF patients using mass-spectrometry. Heart failure (HF) was characterized by reduced neutrophil mNEP compared to controls (p < 0.01). NEP activity on peripheral blood cells was almost 4-fold higher compared to plasma NEP activity (p = 0.031) and correlated with neutrophil mNEP (p = 0.006). Lower neutrophil mNEP was associated with increasing disease severity and markers of adverse remodeling. Higher neutrophil mNEP was associated with reduced risk for mortality, total cardiovascular hospitalizations, and the composite endpoint of both (p < 0.01 for all). This is the first report describing a significant role of neutrophil mNEP in HFrEF. The biological relevance of neutrophil mNEP and exact effects of angiotensin-converting-enzyme inhibitors (ARNi) at the neutrophil site have to be determined. However, the results may suggest early initiation of ARNi already in less severe HF disease, where effects of NEP inhibition may be more pronounced.

Impacts of Yangxin decoction on the expressions of MMP-9, CaN, NFAT3 and GATA4 in myocardial tissue of rats with chronic heart failure

To investigate the impacts of Yangxin decoction on the expressions of matrix metalloproteinase 9 (MMP-9), calcineurin (CaN), T cell activated nuclear factor 3 (NFAT3) and zinc finger transcription factor 4 (GATA4) in myocardial tissue of rats with chronic heart failure (CHF). 50 healthy SD rats were randomly divided into the normal control group (n = 10) and the operation group (n = 40). After successful modeling, the rats were randomly divided into 4 groups. And they were treated with Yangxin decoctions of low concentration (1.5 g/kg), medium concentration (2.5 g/kg), high concentration (3.5 g/kg) and distilled water (for 4 weeks). The LVSP, SAP, DAP and LVEDP in Yangxin decoction treatment groups were significantly superior to the model group. The LVEF, LVIDd and LVIDs in Yangxin decoction treatment groups were significantly superior to the model group. The activity of CaN in each group treated with Yangxin decoction was significantly lower than that in the model group. The expression levels of MMP-9, NFAT3, GATA4 protein in each group treated with Yangxin decoction were significantly lower than that in the model group.. Yangxin decoction can significantly improve the cardiac function, reduce CaN activity, decrease the expression levels of MMP-9, NFAT3 and GATA4, inhibit CaN/NFAT3 signaling pathway, increase myocardial remodeling and protect myocardial tissue in rats with CHF.

The role of demethylases in cardiac development and disease

Heart failure is a worldwide health condition that currently has limited noninvasive treatments. Heart disease includes both structural and molecular remodeling of the heart which is driven by alterations in gene expression in the cardiomyocyte. Therefore, understanding the regulatory mechanisms which instigate these changes in gene expression and constitute the foundation for pathological remodeling may be beneficial for developing new treatments for heart disease. These gene expression changes are largely preceded by epigenetic alterations to chromatin, including the post-translational modification of histones such as methylation, which alters chromatin to be more or less accessible for transcription factors or regulatory proteins to bind and modify gene expression. Methylation was once thought to be a permanent mark placed on histone or non-histone targets by methyltransferases, but is now understood to be a reversible process after the discovery of the first demethylase, KDM1A/LSD1. Since this time, it has been shown that demethylases play key roles in embryonic development, in maintaining cellular homeostasis and disease progression. However, the role of demethylases in the fetal and adult heart remains largely unknown. In this review, we have compiled data on the 33 mammalian demethylases that have been identified to date and evaluate their expression in the embryonic and adult heart as well as changes in expression in the failing myocardium using publicly available RNA-sequencing and proteomic datasets. Our analysis detected expression of 14 demethylases in the normal fetal heart, and 5 demethylases in the normal adult heart. Moreover, 8 demethylases displayed differential expression in the diseased human heart compared to healthy hearts. We then examined the literature regarding these demethylases and provide phenotypic information of 13 demethylases that have been functionally interrogated in some way in the heart. Lastly, we describe the 6 arginine and lysine residues on histones which have been shown to be methylated but have no corresponding demethylase identified which removes these methyl marks. Overall, this review highlights our current knowledge on the role of demethylases, their importance in cardiac development and pathophysiology and provides evidence for the use of pharmacological inhibitors to combat disease.

Effects of Hsp90 inhibitor on the RIP1-RIP3-MLKL pathway during the development of heart failure in mice

Necroptosis is a programmed form of necrotic cell death. Necroptosis is regulated by the necroptosis-regulating proteins including receptor-interacting protein (RIP) 1, RIP3, and mixed lineage kinase domain-like (MLKL), the activities of which are modulated by the molecular chaperone heat-shock protein (Hsp) 90. Presently, to clarify the relationship between Hsp90 and necroptotic pathway proteins, RIP1, RIP3, and MLKL in the development of heart failure, we examined the effects of Hsp90 inhibitor treatment on the RIP1-RIP3-MLKL pathway in mice following transverse aortic constriction (TAC). In this study, TAC mice showed typical signs of heart failure at the 8th week after the operation. In the failing heart, the levels of these regulatory proteins and those of their phosphorylated forms were increased, suggesting that necroptosis contributed to the development of heart failure in the TAC mice. The increases in RIP1, RIP3, and MLKL after TAC were reversed by the administration of an Hsp90 inhibitor. Furthermore, the rise in the phosphorylation levels of these 3 proteins were attenuated by the Hsp90 inhibitor. Concomitantly, cardiac functions were preserved. We also found that exposure of cultured adult mouse cardiomyocytes to the Hsp90 inhibitor attenuated necrotic cell death induced by tumor necrosis factor-α via suppression of RIP1, RIP3, and MLKL activation in in vitro experiments. Taken together, our findings suggest that inhibition of Hsp90 should have therapeutic effects by reducing the activation of RIP1-RIP3-MLKL pathway in the hypertrophied heart and thus could be a new therapeutic strategy for chronic heart failure.

Nuanxin capsule enhances cardiac function by inhibiting oxidative stress-induced mitochondrial dependent apoptosis through AMPK/JNK signaling pathway

OBJECTIVE

Oxidative stress and apoptosis play critical roles in the pathogenesis of heart failure (HF).Nuanxin capsule (NX) is a Chinese medicine that has outstanding protective effects on HF. The present study aimed to elucidate whether NX could protect HF against oxidative stress-induced apoptosis through intrinsic mitochondrial pathway.

METHODS

In vivo, HF was induced by transverse aortic constriction. NX and Compound C (Comp C) were administered to C57BL/6 J mice for over a 4-week period. Cardiac function was assessed with echocardiography. In vitro, H9c2 cells were exposed to H2O2 in the presence or absence of NX and Compound C. Cell viability, cytotoxicity, reactive oxygen species (ROS) production, apoptosis, mitochondrial membrane potential (ΔΨm) and mitochondrial function by oxygen consumption rate (OCR) were detected. The expressions of cytochrome c, BAX, Bcl-2, cleaved caspase-3, AMPK and JNK were evaluated by western blotting.

RESULTS

The results indicated that NX significantly improved cardiac function and enhanced the cell viability, ΔΨm and mitochondrial respiration. Also NX treatment reduced cell cytotoxicity and ROS production. Moreover, NX inhibited mitochondrial-mediated apoptosis by upregulating AMPK and downregulating JNK both in vivo and in vitro. The protective effects of NX on cardiac function by reducing oxidative stress-induced mitochondrial dependent apoptosis were reversed by Compound C treatment.

CONCLUSIONS

These findings demonstrated that NX effectively improved cardiac function in TAC mice by reducing oxidative stress-induced mitochondrial dependent apoptosis by activating AMPK/JNK signaling pathway.

Amylin deposition activates HIF1α and 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3) signaling in failing hearts of non-human primates

Hyperamylinemia induces amylin aggregation and toxicity in the pancreas and contributes to the development of type-2 diabetes (T2D). Cardiac amylin deposition in patients with obesity and T2D was found to accelerate heart dysfunction. Non-human primates (NHPs) have similar genetic, metabolic, and cardiovascular processes as humans. However, the underlying mechanisms of cardiac amylin in NHPs, particularly related to the hypoxia inducible factor (HIF)1α and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) signaling pathways, are unknown. Here, we demonstrate that in NHPs, amylin deposition in heart failure (HF) contributes to cardiac dysfunction via activation of HIF1α and PFKFB3 signaling. This was confirmed in two in vitro cardiomyocyte models. Furthermore, alterations of intracellular Ca2+, reactive oxygen species, mitochondrial function, and lactate levels were observed in amylin-treated cells. Our study demonstrates a pathological role for amylin in the activation of HIF1α and PFKFB3 signaling in NHPs with HF, establishing amylin as a promising target for heart disease patients.

Empagliflozin improves endothelial and cardiomyocyte function in human heart failure with preserved ejection fraction via reduced pro-inflammatory-oxidative pathways and protein kinase Gα oxidation

AIMS

Sodium-glucose-cotransporter-2 inhibitors showed favourable cardiovascular outcomes, but the underlying mechanisms are still elusive. This study investigated the mechanisms of empagliflozin in human and murine heart failure with preserved ejection fraction (HFpEF).

METHODS AND RESULTS

The acute mechanisms of empagliflozin were investigated in human myocardium from patients with HFpEF and murine ZDF obese rats, which were treated in vivo. As shown with immunoblots and ELISA, empagliflozin significantly suppressed increased levels of ICAM-1, VCAM-1, TNF-α, and IL-6 in human and murine HFpEF myocardium and attenuated pathological oxidative parameters (H2O2, 3-nitrotyrosine, GSH, lipid peroxide) in both cardiomyocyte cytosol and mitochondria in addition to improved endothelial vasorelaxation. In HFpEF, we found higher oxidative stress-dependent activation of eNOS leading to PKGIα oxidation. Interestingly, immunofluorescence imaging and electron microscopy revealed that oxidized PKG1α in HFpEF appeared as dimers/polymers localized to the outer-membrane of the cardiomyocyte. Empagliflozin reduced oxidative stress/eNOS-dependent PKGIα oxidation and polymerization resulting in a higher fraction of PKGIα monomers, which translocated back to the cytosol. Consequently, diminished NO levels, sGC activity, cGMP concentration, and PKGIα activity in HFpEF increased upon empagliflozin leading to improved phosphorylation of myofilament proteins. In skinned HFpEF cardiomyocytes, empagliflozin improved cardiomyocyte stiffness in an anti-oxidative/PKGIα-dependent manner. Monovariate linear regression analysis confirmed the correlation of oxidative stress and PKGIα polymerization with increased cardiomyocyte stiffness and diastolic dysfunction of the HFpEF patients.

CONCLUSION

Empagliflozin reduces inflammatory and oxidative stress in HFpEF and thereby improves the NO-sGC-cGMP-cascade and PKGIα activity via reduced PKGIα oxidation and polymerization leading to less pathological cardiomyocyte stiffness.

Relation of Aspartate Aminotransferase to Alanine Aminotransferase Ratio to Nutritional Status and Prognosis in Patients With Acute Heart Failure

Elevated liver fibrosis markers are associated with worse prognosis in acute heart failure (AHF). The aspartate aminotransferase to alanine aminotransferase ratio (AAR) is one such fibrosis marker, and low ALT is a surrogate marker of malnutrition. Here, we evaluated the association between AAR and nutritional status and prognosis in patients with AHF. Consecutive 774 patients who were admitted due to AHF were divided into 3 groups according to AAR at discharge: first tertile, AAR<1.16 (n = 262); second tertile, 1.16≤AAR<1.70 (n = 257); and third tertile, AAR≥1.70 (n = 255). Nutritional indices and a composite of all-cause death or HF rehospitalization were compared in the 3 tertiles. Patients in the third AAR tertile were older and had lower body mass index than patients in other AAR tertiles. A higher AAR was associated with worse nutritional indices (i.e., controlling nutritional status score, geriatric nutritional risk index, and prognostic nutritional index). Clinical outcome rates significantly increased along AAR tertiles (first tertile, 28%; second tertile, 43%; third tertile, 58%, p < 0.001). Cox proportional hazards models including potential prognostic factors revealed high AAR was an independent prognostic factor of AHF. In conclusion, AAR at discharge may be associated with nutritional status and worse clinical outcomes in patients with AHF.

Nox2+ myeloid cells drive vascular inflammation and endothelial dysfunction in heart failure after myocardial infarction via angiotensin II receptor type 1

AIMS

Heart failure (HF) ensuing myocardial infarction (MI) is characterized by the initiation of a systemic inflammatory response. We aimed to elucidate the impact of myelomonocytic cells and their activation by angiotensin II on vascular endothelial function in a mouse model of HF after MI.

METHODS AND RESULTS

HF was induced in male C57BL/6J mice by permanent ligation of the left anterior descending coronary artery. Compared to sham, HF mice had significantly impaired endothelial function accompanied by enhanced mobilization of Sca-1+c-Kit+ haematopoietic stem cells and Sca-1-c-Kit+ common myeloid and granulocyte-macrophage progenitors in the bone marrow as well as increased vascular infiltration of CD11b+Ly6G-Ly6Chigh monocytes and accumulation of CD11b+ F4/80+ macrophages, assessed by flow cytometry. Using mice with Cre-inducible expression of diphtheria toxin receptor in myeloid cells, we selectively depleted lysozyme M+ myelomonocytic cells for 10 days starting 28 days after MI. While the cardiac phenotype remained unaltered until 38 days post-MI, myeloid cell depletion attenuated vascular accumulation of Nox2+CD45+ cells, endothelial dysfunction, oxidative stress, and vascular expression of adhesion molecules and angiotensin II receptor type 1 (AT1R). Pharmacological blockade of this receptor for 4 weeks did not significantly alter cardiac function, but mimicked the effects of myeloid cell depletion: telmisartan (20 mg/kg/day, fed to C57BL/6J mice) diminished bone marrow myelopoesis and myeloid reactive oxygen species production, attenuated endothelial leucocyte rolling and vascular accumulation of CD11b+Ly6G-Ly6Chigh monocytes and macrophages, resulting in improved vascular function with less abundance of Nox2+CD45+ cells.

CONCLUSION

Endothelial dysfunction in HF ensuing MI is mediated by inflammatory Nox2+ myeloid cells infiltrating the vessel wall that can be targeted by AT1R blockade.

Redox-Resistant SERCA [Sarco(endo)plasmic Reticulum Calcium ATPase] Attenuates Oxidant-Stimulated Mitochondrial Calcium and Apoptosis in Cardiac Myocytes and Pressure Overload-Induced Myocardial Failure in Mice

BACKGROUND

SERCA [sarco(endo)plasmic reticulum calcium ATPase] is regulated by oxidative posttranslational modifications at cysteine 674 (C674). Because sarcoplasmic reticulum (SR) calcium has been shown to play a critical role in mediating mitochondrial dysfunction in response to reactive oxygen species, we hypothesized that SERCA oxidation at C674 would modulate the effects of reactive oxygen species on mitochondrial calcium and mitochondria-dependent apoptosis in cardiac myocytes.

METHODS

Adult rat ventricular myocytes expressing wild-type SERCA2b or a redox-insensitive mutant in which C674 is replaced by serine (C674S) were exposed to H2O2 (100 µmol/Lμ). Free mitochondrial calcium concentration was measured in adult rat ventricular myocytes with a genetically targeted fluorescent probe, and SR calcium content was assessed by measuring caffeine-stimulated release. Mice with heterozygous knock-in of the SERCA C674S mutation were subjected to chronic ascending aortic constriction.

RESULTS

In adult rat ventricular myocytes expressing wild-type SERCA, H2O2 caused a 25% increase in mitochondrial calcium concentration that was associated with a 50% decrease in SR calcium content, both of which were prevented by the ryanodine receptor inhibitor tetracaine. In cells expressing the C674S mutant, basal SR calcium content was decreased by 31% and the H2O2-stimulated rise in mitochondrial calcium concentration was attenuated by 40%. In wild-type cells, H2O2 caused cytochrome c release and apoptosis, both of which were prevented in C674S-expressing cells. In myocytes from SERCA knock-in mice, basal SERCA activity and SR calcium content were decreased. To test the effect of C674 oxidation on apoptosis in vivo, SERCA knock-in mice were subjected to chronic ascending aortic constriction. In wild-type mice, ascending aortic constriction caused myocyte apoptosis, LV dilation, and systolic failure, all of which were inhibited in SERCA knock-in mice.

CONCLUSIONS

Redox activation of SERCA C674 regulates basal SR calcium content, thereby mediating the pathologic reactive oxygen species-stimulated rise in mitochondrial calcium required for myocyte apoptosis and myocardial failure.

Clinical and Proteomic Correlates of Plasma ACE2 (Angiotensin-Converting Enzyme 2) in Human Heart Failure

ACE2 (angiotensin-converting enzyme 2) is a key component of the renin-angiotensin-aldosterone system. Yet, little is known about the clinical and biologic correlates of circulating ACE2 levels in humans. We assessed the clinical and proteomic correlates of plasma (soluble) ACE2 protein levels in human heart failure. We measured plasma ACE2 using a modified aptamer assay among PHFS (Penn Heart Failure Study) participants (n=2248). We performed an association study of ACE2 against ≈5000 other plasma proteins measured with the SomaScan platform. Plasma ACE2 was not associated with ACE inhibitor and angiotensin-receptor blocker use. Plasma ACE2 was associated with older age, male sex, diabetes mellitus, a lower estimated glomerular filtration rate, worse New York Heart Association class, a history of coronary artery bypass surgery, and higher pro-BNP (pro-B-type natriuretic peptide) levels. Plasma ACE2 exhibited associations with 1011 other plasma proteins. In pathway overrepresentation analyses, top canonical pathways associated with plasma ACE2 included clathrin-mediated endocytosis signaling, actin cytoskeleton signaling, mechanisms of viral exit from host cells, EIF2 (eukaryotic initiation factor 2) signaling, and the protein ubiquitination pathway. In conclusion, in humans with heart failure, plasma ACE2 is associated with various clinical factors known to be associated with severe coronavirus disease 2019 (COVID-19), including older age, male sex, and diabetes mellitus, but is not associated with ACE inhibitor and angiotensin-receptor blocker use. Plasma ACE2 protein levels are prominently associated with multiple cellular pathways involved in cellular endocytosis, exocytosis, and intracellular protein trafficking. Whether these have a causal relationship with ACE2 or are relevant to novel coronavirus-2 infection remains to be assessed in future studies.

Chrysophanol Protects Against Acute Heart Failure by Inhibiting JNK1/2 Pathway in Rats

BACKGROUND Acute heart failure (AHF) usually requires urgent therapy. Myocardial damage, oxidative stress, and inflammation are major components in the pathology of AHF. This study was designed to investigate the effects of chrysophanol on AHF. MATERIAL AND METHODS Sprague-Dawley rats were injected with isoprenaline hydrochloride to construct AHF rat models. AHF rats were treated with normal saline (negative control), chrysophanol, the combination of chrysophanol and SP600125, or benazepril (positive control) using sham rats as blank controls. Echocardiography, histological staining, and enzyme activity analysis were performed to assess the heart functions and myocardial damage. Effects on apoptosis, oxidative stress (OS), and inflammation were evaluated by biochemical analysis, TUNEL staining, and ELISA. RESULTS Chrysophanol improved the parameters of cardiac functions and alleviated the myocardial damage accompanied by the reduction of creatine kinase and lactate dehydrogenase activity. Meanwhile, chrysophanol inhibited the myocardial apoptosis along with the upregulation of Bcl-2 and downregulation of Bax and cleaved caspase-3. AHF-induced abnormal changes of OS parameters (MDA, GPx, CAT, SOD) and inflammatory markers (IL-6, IL-1ß, TNF-alpha, IFN-γ) were alleviated by chrysophanol. Benazepril treatment showed similar results with chrysophanol, while the addition of SP600125 enhanced the chrysophanol-mediated protection effects in AHF rats. Western blot analysis demonstrated that chrysophanol inhibited the phosphorylation of JNK1/2 and its upstream/downstream factors. CONCLUSIONS Chrysophanol improved cardiac functions and protected against myocardial damage, apoptosis, OS, and inflammation by inhibiting activation of the JNK1/2 pathway in AHF rat models. These finding indicate that chrysophanol may be a promising approach for treatment of AHF.

A Common Missense Variant in OMA1 Associated with the Prognosis of Heart Failure

PURPOSE

Mitochondrial dysfunction plays a vital role in the pathophysiologic process of heart failure (HF). As a quality control system, mitochondrial fusion and fission are under control of mitochondrial fusion and fission-related proteins. The objective of this study was to investigate the effects of common variants in mitochondrial fusion and fission-related genes on the prognosis of HF.

METHODS

We performed whole exome sequencing (WES) with 1000 HF patients; the statistically significant variant was further genotyped in the replicated population with 2324 HF patients. A series of function analysis including western blot, cell proliferation assay, and in vitro OMA1 activity assay were conducted to illuminate the underlying mechanism.

RESULTS

We identified a missense variant rs17117699 associated with the prognosis of HF in group without β-blocker use rather than with β-blocker use in two-stage population: adjusted P = 0.79, HR = 0.88 (0.36-2.13) in group with β-blocker use and adjusted P = 0.016, HR = 1.43 (1.07-1.91) in group without β-blocker in first-stage population; adjusted P = 0.42, HR = 0.85 (0.56-1.28) in group with β-blocker use and adjusted P = 0.015, HR = 1.39 (1.06-1.82) in group without β-blocker in replicated stage. Functional analysis indicated that rs17117699-G allele increased the activity of OMA1 assessed by the ratio of S-OPA1 to L-OPA1 and suppressed cells proliferation under ISO treatment when compared with rs17117699-T allele. Furthermore, OMA1 functioned downstream of β-adrenergic receptor signaling and ISO-induced OPA1 cleavage is dependent on OMA1.

CONCLUSIONS

Our findings demonstrate that rs17117699T>G in OMA1 increases the risk of HF mortality via enhancing its OPA1 cleavage activity. It is a promising potential treatment target for HF.

CLINICAL TRIAL REGISTRATION

NCT03461107. https://www.clinicaltrials.gov/ct2/show/NCT03461107?term=03461107&cond=Heart+Failure&cntry=CN&rank=1.

Glutamyl-Prolyl-tRNA Synthetase Regulates Proline-Rich Pro-Fibrotic Protein Synthesis During Cardiac Fibrosis

RATIONALE

Increased protein synthesis of profibrotic genes is a common feature in cardiac fibrosis and heart failure. Despite this observation, critical factors and molecular mechanisms for translational control of profibrotic genes during cardiac fibrosis remain unclear.

OBJECTIVE

To investigate the role of a bifunctional ARS (aminoacyl-tRNA synthetase), EPRS (glutamyl-prolyl-tRNA synthetase) in translational control of cardiac fibrosis.

METHODS AND RESULTS

Results from reanalyses of multiple publicly available data sets of human and mouse heart failure, demonstrated that EPRS acted as an integrated node among the ARSs in various cardiac pathogenic processes. We confirmed that EPRS was induced at mRNA and protein levels (≈1.5-2.5-fold increase) in failing hearts compared with nonfailing hearts using our cohort of human and mouse heart samples. Genetic knockout of one allele of Eprs globally (Eprs+/-) using CRISPR-Cas9 technology or in a Postn-Cre-dependent manner (Eprsflox/+; PostnMCM/+) strongly reduces cardiac fibrosis (≈50% reduction) in isoproterenol-, transverse aortic constriction-, and myocardial infarction (MI)-induced heart failure mouse models. Inhibition of EPRS using a PRS (prolyl-tRNA synthetase)-specific inhibitor, halofuginone, significantly decreases translation efficiency (TE) of proline-rich collagens in cardiac fibroblasts as well as TGF-β (transforming growth factor-β)-activated myofibroblasts. Overexpression of EPRS increases collagen protein expression in primary cardiac fibroblasts under TGF-β stimulation. Using transcriptome-wide RNA-Seq and polysome profiling-Seq in halofuginone-treated fibroblasts, we identified multiple novel Pro-rich genes in addition to collagens, such as Ltbp2 (latent TGF-β-binding protein 2) and Sulf1 (sulfatase 1), which are translationally regulated by EPRS. SULF1 is highly enriched in human and mouse myofibroblasts. In the primary cardiac fibroblast culture system, siRNA-mediated knockdown of SULF1 attenuates cardiac myofibroblast activation and collagen deposition. Overexpression of SULF1 promotes TGF-β-induced myofibroblast activation and partially antagonizes anti-fibrotic effects of halofuginone treatment.

CONCLUSIONS

Our results indicate that EPRS preferentially controls translational activation of proline codon rich profibrotic genes in cardiac fibroblasts and augments pathological cardiac remodeling. Graphical Abstract: A graphical abstract is available for this article.

The partnership between renalase and ejection fraction as a risk factor for increased cardiac remodeling biomarkers in chronic heart failure patients

Objective: Heart failure (HF) represents a huge socio-economic burden. It has been demonstrated, experimentally, that renalase, a newly discovered protein, prevents cardiac hypertrophy and adverse remodeling, which is seen in HF. We postulated the following aims: to investigate associations of renalase with biomarkers of cardiac remodeling: galectin-3, soluble suppression of tumorigenicity, (sST2), growth differentiation factor 15 (GDF-15) and syndecan-1, myocardial stretch (BNP) and cardio-renal axis (cystatin C) in HF patients with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF) to determine whether renalase, in combination with left ventricular ejection fraction (LVEF), represents a risk factor for plasma elevation in biomarkers.Methods: We classified HF patients (n = 76) according to LVEF (preserved/reduced), applied a median plasma renalase (113 ng/mL) as a cut-off value (low/high) and created four subgroups of HF patients: HFpEF/low renalase (n = 19), HFrEF/low renalase (n = 19), HFrEF/high renalase (n = 32) and HFpEF/high renalase (n = 6). A control group (n = 35) consisted of healthy volunteers.Results: Plasma concentrations of evaluated biomarkers were determined using an ELISA technique and were highest in HF patients with reduced EF (p < .001, respectively), and renalase's positive correlations were obtained relating to all biomarkers: galectin-3 (r = 0.913; p < .001), sST2 (r = 0.965; p < .001), GDF-15 (r = 0.887; p < .001), syndecan-1 (r = 0.922; p < .001), BNP (r = 0.527; p < .001) and cystatin C (r = 0.844; p < .001) and strong and negative correlation with LVEF (r = -0.456, p < .001). Increased renalase, regardless of the EF (preserved/reduced), was shown to be an independent risk factor for an increase in all evaluated cardiac remodeling biomarkers, p < .001, respectively. However, increased renalase and reduced EF was the only independent risk factor for BNP and cystatin C elevation, p < .001, respectively. Results after multivariable adjustments (age/gender) were identical.Conclusion: When elevated plasma renalase and HF are present, regardless of EF being reduced or preserved, that represents a significant risk factor for increase in cardiac remodeling biomarker plasma concentrations. However, only elevated renalase and reduced EF demonstrated significance as a risk factor for BNP and cystatin C plasma elevation. Renalase may be considered a promising molecule for the improved predictive abilities of conventional biomarkers and is worthy of further investigation.

Antioxidative enzyme activity and total antioxidant capacity in serum of dogs with degenerative mitral valve disease

This study was designed to evaluate the antioxidative status of serum by measuring its total antioxidant capacity, as well as the antioxidant enzyme activity (superoxide dismutase, catalase, and glutathione reductase), in dogs with various stages of degenerative mitral valve disease (DMVD) compared to healthy controls. In total, 71 client-owned dogs in different stages of DMVD, which included healthy controls, took part in the study. Following an anamnesis, clinical examination, standard transthoracic echocardiograpic examination, chest X-ray, complete blood (cell) count, and serum biochemistry, dogs were divided into 2 study groups. Blood was drawn from each dog once at the time of presentation and selected antioxidant parameters were measured using commercially available assay kits. The activity of superoxide dismutase gradually decreased in the more advanced stages of DMVD, while the activity of catalase was significantly higher in the group of dogs with asymptomatic DMVD compared to healthy controls and dogs with symptomatic DMVD. No significant changes were noted in total antioxidant capacity and the activity of glutathione reductase. Results suggested that DMVD has a significant impact on the activity of superoxide dismutase and catalase in the serum of the tested dogs. Knowledge of changes in the activity of antioxidative enzymes may warrant further studies, possibly to evaluate the potential role of compounds with antioxidative properties in the clinical outcome of dogs with DMVD.

Role of CyPA in cardiac hypertrophy and remodeling

Pathological cardiac hypertrophy is a complex process and eventually develops into heart failure, in which the heart responds to various intrinsic or external stress, involving increased interstitial fibrosis, cell death and cardiac dysfunction. Studies have shown that oxidative stress is an important mechanism for this maladaptation. Cyclophilin A (CyPA) is a member of the cyclophilin (CyPs) family. Many cells secrete CyPA to the outside of the cells in response to oxidative stress. CyPA from blood vessels and the heart itself participate in a variety of signaling pathways to regulate the production of reactive oxygen species (ROS) and mediate inflammation, promote cardiomyocyte hypertrophy and proliferation of cardiac fibroblasts, stimulate endothelial injury and vascular smooth muscle hyperplasia, and promote the dissolution of extracellular matrix (ECM) by activating matrix metalloproteinases (MMPs). The events triggered by CyPA cause a decline of diastolic and systolic function and finally lead to the occurrence of heart failure. This article aims to introduce the role and mechanism of CyPA in cardiac hypertrophy and remodeling, and highlights its potential role as a disease biomarker and therapeutic target.

Both gain and loss of Nampt function promote pressure overload-induced heart failure

The heart requires high-energy production, but metabolic ability declines in the failing heart. Nicotinamide phosphoribosyl-transferase (Nampt) is a rate-limiting enzyme in the salvage pathway of nicotinamide adenine dinucleotide (NAD) synthesis. NAD is directly involved in various metabolic processes and may indirectly regulate metabolic gene expression through sirtuin 1 (Sirt1), an NAD-dependent protein deacetylase. However, how Nampt regulates cardiac function and metabolism in the failing heart is poorly understood. Here we show that pressure-overload (PO)-induced heart failure is exacerbated in both systemic Nampt heterozygous knockout (Nampt+/-) mice and mice with cardiac-specific Nampt overexpression (Tg-Nampt). The NAD level declined in Nampt+/- mice under PO (wild: 377 pmol/mg tissue; Nampt+/-: 119 pmol/mg tissue; P = 0.028). In cultured cardiomyocytes, Nampt knockdown diminished mitochondrial NAD content and ATP production (relative ATP production: wild: 1; Nampt knockdown: 0.56; P = 0.0068), suggesting that downregulation of Nampt induces mitochondrial dysfunction. On the other hand, the NAD level was increased in Tg-Nampt mice at baseline but not during PO, possibly due to increased consumption of NAD by Sirt1. The expression of Sirt1 was increased in Tg-Nampt mice, in association with reduced overall protein acetylation. PO-induced downregulation of metabolic genes was exacerbated in Tg-Nampt mice. In cultured cardiomyocytes, Nampt and Sirt1 cooperatively suppressed mitochondrial proteins and ATP production, thereby promoting mitochondrial dysfunction. In addition, Nampt overexpression upregulated inflammatory cytokines, including TNF-α and monocyte chemoattractant protein-1. Thus endogenous Nampt maintains cardiac function and metabolism in the failing heart, whereas Nampt overexpression is detrimental during PO, possibly due to excessive activation of Sirt1, suppression of mitochondrial function, and upregulation of proinflammatory mechanisms.NEW & NOTEWORTHY Nicotinamide phosphoribosyl-transferase (Nampt) is a rate-limiting enzyme in the salvage pathway of nicotinamide adenine dinucleotide synthesis. We demonstrate that pressure overload-induced heart failure is exacerbated in both systemic Nampt heterozygous knockout mice and mice with cardiac-specific Nampt overexpression. Both loss- and gain-of-function models exhibited reduced protein acetylation, suppression of metabolic genes, and mitochondrial energetic dysfunction. Thus endogenous Nampt maintains cardiac function and metabolism in the failing heart, but cardiac-specific Nampt overexpression is detrimental rather than therapeutic.

Lipoxygenase drives lipidomic and metabolic reprogramming in ischemic heart failure

BACKGROUND

After myocardial infarction (MI), delayed progression or reversal of cardiac remodeling is a prime target to limit advanced chronic heart failure (HF). However, the temporal kinetics of lipidomic and systemic metabolic signaling is unclear in HF. There is no consensus on metabolic and lipidomic signatures that influence structure, function, and survival in HF. Here we use genetic knock out model to delineate lipidomic, and metabolic changes to describe the role of lipoxygenase in advancing ischemic HF driven by leukocyte activation with signs of non-resolving inflammation. Bioactive lipids and metabolites are implicated in acute and chronic HF, and the goal of this study was to define the role of lipoxygenase in temporal kinetics of lipidomic and metabolic reprogramming in HF.

MATERIALS AND METHODS

To address this question, we used a permanent coronary ligation mouse model which showed profound metabolic and lipidomic reprogramming in acute HF. Additionally, we defined the lipoxygenase-mediated changes in cardiac pathophysiology in acute and chronic HF. For this, we quantitated systemic metabolic changes and lipidomic profiling in infarcted heart tissue with obvious structural remodeling and cardiac dysfunction progressing from acute to chronic HF in the survival cohort.

RESULTS

After MI, lipoxygenase-derived specialized pro-resolving mediators were quantitated and showed lipoxygenase-deficient mice (12/15LOX^-/-) biosynthesize epoxyeicosatrienoic acid (EETs; cypoxins) to facilitate cardiac healing. Lipoxygenase-deficient mice reduced diabetes risk biomarker 2-aminoadipic acid with profound alterations of plasma metabolic signaling of hexoses, amino acids, biogenic amines, acylcarnitines, glycerophospholipids, and sphingolipids in acute HF, thereby improved survival.

CONCLUSION

Specific lipoxygenase deletion alters lipidomic and metabolic signatures, with modified leukocyte profiling that delayed HF progression and improved survival. Future studies are warranted to define the molecular network of lipidome and metabolome in acute and chronic HF patients.

Calcium/calmodulin-dependent protein kinase II causes atrial structural remodeling associated with atrial fibrillation and heart failure

BACKGROUND

Atrial fibrillation (AF) is sustained by reentrant mechanisms that depend, in part, on atrial structural remodeling. Increased Ca2+/calmodulin-dependent protein kinase II (CaMKII) activity occurs in persistent AF. A general consensus has been that electrophysiological actions of CaMKII must be the contributing factor, but electrical remodeling in AF differs considerably with electrophysiological effects of CaMKII. CaMKII has been associated with structural remodeling in several tissues, but not the cardiac atria. The role of CaMKII in sustaining AF remains undefined.

OBJECTIVE

The purpose of this study was to assess the effects of CaMKII on AF-related structural remodeling.

METHODS

We evaluated the objective in a porcine AF-heart failure model using atrial gene transfer of the CaMKII inhibitory peptide CaMKIIn. We used conventional methods including in vivo electrophysiological study, telemetry, western blot, echocardiography, and histology to quantify rhythm, function, microstructure, and signaling pathways relevant to CaMKII and structural remodeling.

RESULTS

CaMKII levels and activity increased progressively in the early stages of AF-heart failure. Inhibiting CaMKII preserved atrial contractile function and attenuated atrial hypertrophy, fibrosis, and apoptosis but did not affect inflammation or myolysis. These effects were accompanied by significantly decreased phosphorylation of HDAC4, decreased expression of p38MAP-kinase, and alterations in the phosphorylation pattern and relative ratios of JNK isoforms.

CONCLUSION

Our findings suggest that CaMKII mediates signaling pathways related to atrial contractile function and structural remodeling in AF. CaMKII inhibition is potentially a novel therapy for AF. These findings are of importance because no clinically relevant mediators of either atrial contractile function or structural remodeling have yet been identified.

Therapeutic Effect of Targeting Branched-Chain Amino Acid Catabolic Flux in Pressure-Overload Induced Heart Failure

Background Branched-chain amino acid (BCAA) catabolic defect is an emerging metabolic hallmark in failing hearts in human and animal models. The therapeutic impact of targeting BCAA catabolic flux under pathological conditions remains understudied. Methods and Results BT2 (3,6-dichlorobenzo[b]thiophene-2-carboxylic acid), a small-molecule inhibitor of branched-chain ketoacid dehydrogenase kinase, was used to enhance BCAA catabolism. After 2 weeks of transaortic constriction, mice with significant cardiac dysfunctions were treated with vehicle or BT2. Serial echocardiograms showed continuing pathological deterioration in left ventricle of the vehicle-treated mice, whereas the BT2-treated mice showed significantly preserved cardiac function and structure. Moreover, BT2 treatment improved systolic contractility and diastolic mechanics. These therapeutic benefits appeared to be independent of impacts on left ventricle hypertrophy but associated with increased gene expression involved in fatty acid utilization. The BT2 administration showed no signs of apparent toxicity. Conclusions Our data provide the first proof-of-concept evidence for the therapeutic efficacy of restoring BCAA catabolic flux in hearts with preexisting dysfunctions. The BCAA catabolic pathway represents a novel and potentially efficacious target for treatment of heart failure.