Voltage-dependent anion channel 1 (VDAC1) overexpression alleviates cardiac fibroblast activation in cardiac fibrosis via regulating fatty acid metabolism.

Cardiac fibrosis is characterized by the excessive deposition of extracellular matrix in the myocardium with cardiac fibroblast activation, leading to chronic cardiac remodeling and dysfunction. However, little is known about metabolic alterations in fibroblasts during cardiac fibrosis, and there is a lack of pharmaceutical treatments that target metabolic dysregulation. Here, we provided evidence that fatty acid ß-oxidation (FAO) dysregulation contributes to fibroblast activation and cardiac fibrosis. With transcriptome, metabolome, and functional assays, we demonstrated that FAO was downregulated during fibroblast activation and cardiac fibrosis, and that perturbation of FAO reversely affected the fibroblast-to-myofibroblast transition. The decrease in FAO may be attributed to reduced long-chain fatty acid (LCFA) uptake. Voltage-dependent anion channel 1 (VDAC1), the main gatekeeper of the outer mitochondrial membrane (OMM), serves as the transporter of LCFA into the mitochondria for further utilization and has been shown to be decreased in myofibroblasts. In vitro, the addition of exogenous VDAC1 was shown to ameliorate cardiac fibroblast activation initiated by transforming growth factor beta 1 (TGF-ß1) stimuli, and silencing of VDAC1 displayed the opposite effect. A mechanistic study revealed that VDAC1 exerts a protective effect by regulating LCFA uptake into the mitochondria, which is impaired by an inhibitor of carnitine palmitoyltransferase 1A. In vivo, AAV9-mediated overexpression of VDAC1 in myofibroblasts significantly alleviated transverse aortic constriction (TAC)-induced cardiac fibrosis and rescued cardiac function in mice. Finally, we treated mice with the VDAC1-derived R-Tf-D-LP4 peptide, and the results showed that R-Tf-D-LP4 prevented TAC-induced cardiac fibrosis and dysfunction in mice. In conclusion, this study provides evidence that VDAC1 maintains FAO metabolism in cardiac fibroblasts to repress fibroblast activation and cardiac fibrosis and suggests that the VDAC1 peptide is a promising drug for rescuing fibroblast metabolism and repressing cardiac fibrosis.

The role of cardiac resident macrophage in cardiac aging.

Advancements in longevity research have provided insights into the impact of cardiac aging on the structural and functional aspects of the heart. Notable changes include the gradual remodeling of the myocardium, the occurrence of left ventricular hypertrophy, and the decline in both systolic and diastolic functions. Macrophages, a type of immune cell, play a pivotal role in innate immunity by serving as vigilant agents against pathogens, facilitating wound healing, and orchestrating the development of targeted acquired immune responses. Distinct subsets of macrophages are present within the cardiac tissue and demonstrate varied functions in response to myocardial injury. The differentiation of cardiac macrophages according to their developmental origin has proven to be a valuable strategy in identifying reparative macrophage populations, which originate from embryonic cells and reside within the tissue, as well as inflammatory macrophages, which are derived from monocytes and recruited to the heart. These subsets of macrophages possess unique characteristics and perform distinct functions. This review aims to summarize the current understanding of the roles and phenotypes of cardiac macrophages in various conditions, including the steady state, aging, and other pathological conditions. Additionally, it will highlight areas that require further investigation to expand our knowledge in this field.

Elevated MCU Expression by CaMKIIδB Limits Pathological Cardiac Remodeling.

BACKGROUND: Calcium (Ca2+) is a key regulator of energy metabolism. Impaired Ca2+ homeostasis damages mitochondria, causing cardiomyocyte death, pathological hypertrophy, and heart failure. This study investigates the regulation and the role of the mitochondrial Ca2+ uniporter (MCU) in chronic stress-induced pathological cardiac remodeling. METHODS: MCU knockout or transgenic mice were infused with isoproterenol (ISO; 10 mg/kg per day, 4 weeks). Cardiac hypertrophy and remodeling were evaluated by echocardiography and histology. Primary cultured rodent adult cardiomyocytes were treated with ISO (1 nmol/L, 48 hours). Intracellular Ca2+ handling and cell death pathways were monitored. Adenovirus-mediated gene manipulations were used in vitro. RESULTS: Chronic administration of the ß-adrenergic receptor agonist ISO increased the levels of the MCU and the MCU complex in cardiac mitochondria, raising mitochondrial Ca2+ concentrations, in vivo and in vitro. ISO also upregulated MCU without affecting its regulatory proteins in adult cardiomyocytes. It is interesting that ISO-induced cardiac hypertrophy, fibrosis, contractile dysfunction, and cardiomyocyte death were exacerbated in global MCU knockout mice. Cardiomyocytes from knockout mice or overexpressing a dominant negative MCU exhibited defective intracellular Ca2+ handling and activation of multiple cell death pathways. Conversely, cardiac-specific overexpression of MCU maintained intracellular Ca2+ homeostasis and contractility, suppressed cell death, and prevented ISO-induced heart hypertrophy. ISO upregulated MCU expression through activation of Ca2+/calmodulin kinase II δB (CaMKIIδB) and promotion of its nuclear translocation via calcineurin-mediated dephosphorylation at serine 332. Nuclear CaMKIIδB phosphorylated CREB (cAMP-response element binding protein), which bound the Mcu promoter to enhance Mcu gene transcription. CONCLUSIONS: The ß-adrenergic receptor/CaMKIIδB/CREB pathway upregulates Mcu gene expression in the heart. MCU upregulation is a compensatory mechanism that counteracts stress-induced pathological cardiac remodeling by preserving Ca2+ homeostasis and cardiomyocyte viability.

Effect of the angiotensin-receptor-neprilysin inhibitor in heart failure patients with left ventricular ejection fraction higher than 40.

The angiotensin-receptor-neprilysin inhibitor (ARNI) reduced cardiovascular deaths and heart failure hospitalization in patients with heart failure of reduced ejection fraction (HFrEF). Its role in non-HFrEF patients was not clear. This study aims to answer this question.In this retrospective study, we enrolled 928 patients diagnosed with non-HFrEF, 492 of them received angiotensin converting enzyme inhibitor (ACEI) and the rest 436 received angiotensin-receptor-neprilysin inhibitor. Outcomes were compared by Kaplan-Meier survival analysis and various clinical parameters were investigated using Cox multivariable analysis, followed by interaction analysis. Minnesota living with heart failure Questionnaire (MLHFQ) was employed as one of the criteria to assess heart failure outcome.The cardiovascular (CV) death or HF hospitalization at 24 months occurred in 49 patients in ACEI group compared with 31 in ARNI group (Hazard Ratio (HR): 1.231, 95% confidence Interval (CI): 1.080-2.460, P = .031). And ARNI showed better prognosis of HF hospitalization (HR: 1.283, 95%CI: 1.065-1.360, P = .038). Cumulative Kaplan-Meier estimates of endpoints, ARNI could reduce the incidence of CV death or HF hospitalization (P = .042) and HF hospitalization (P = .035). The stratified analysis revealed that participants with age less than 70 years old had a lower incidence of CV death or HF hospitalization (HR: 1.194, 95%CI: 1.011-1992, P = .031) after treated with ARNI. Patients received diuretics could benefit from ARNI (HR: 1.383, 95%CI: 1.082-1.471, P = .019). Similar results were also observed in patients with heart rate lower than 90 bpm (HR: 1.556, 95%CI: 1.045-2.386, P = .003) and patients with atrial fibrillation history (HR: 1.873, 95%CI: 1.420-2.809, P = .011). ARNI could improve the quality of life both from the total, emotional and physical aspects.ARNI is an efficacy treatment strategy to improve the outcome and quality of life in patients with non-HFrEF.

Inhibition of Mitofusin-2 Promotes Cardiac Fibroblast Activation via the PERK/ATF4 Pathway and Reactive Oxygen Species.

Mitofusin-2 (Mfn2) is a key outer mitochondrial membrane protein, which maintains normal mitochondrial dynamics and function. However, its role in cardiac fibroblast activation remains poorly understood. In the present study, a rat model of transverse aortic constriction (TAC) was established to observe the cardiac fibroblast activation in vivo. TGF-ß1 treatment for 24 hours was used to induce cardiac fibroblast activation in vitro. As a result, the expression of Mfn2 decreased in the hypertrophic heart tissues and cardiac fibroblasts treated with TGF-ß1. siMfn2 and adenovirus were applied to mediate Mfn2 gene silencing and overexpression in cardiac fibroblasts to elucidate the relationship between Mfn2 and cardiac fibroblast activation, as well as the possible underlying mechanisms. Knockdown of Mfn2 further promoted TGF-ß1-induced cardiac fibroblast activation, while forced expression of Mfn2 attenuated this pathological reaction. The PERK/ATF4 pathway, one of the branches of endoplasmic reticulum (ER) stress, was identified to be involved in this process. Knockdown and overexpression of Mfn2 lead to aggravation or alleviation of the PERK/ATF4 pathway. Blocking this pathway by silencing ATF4 with siATF4 attenuated the pathological process. During the activation of cardiac fibroblasts, knockdown of Mfn2 also increased the production of reactive oxygen species (ROS), while ROS scavenger N-acetyl-l-cysteine (NAC) could attenuate the effect caused by knockdown of Mfn2. Our data suggested that inhibition of Mfn2 could promote cardiac fibroblast activation by activating the PERK/ATF4 signaling pathway and increasing the generation of ROS.

Derivation and Evaluation of the Ischemic Risk Model in High-Risk Chinese Patients Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndrome.

PURPOSE: Coronary artery disease is the top cause of death among the Chinese population. With the establishment of a Chinese prediction model, it is urgent to assess factors related to the prognosis of patients with acute coronary syndrome at extremely high risk. METHODS: In this retrospective study, we enrolled 601 patients assessed as being of extremely high risk, according to specific criteria from the China-PAR (Prediction for Atherosclerotic Cardiovascular Disease Risk) project, and investigated various clinical parameters using Cox multivariate analysis to establish a risk nomogram. C-index and calibration curves were involved to assess the internal identification. By using the all-cause death risk model, we stratified patients by risk level and compared the effects of clopidogrel and ticagrelor on end points. FINDINGS: We identified several factors, including body mass index, angiopathy, smoking status, ß-blocker usage, history of myocardial infarction, total number of stents, and usage of antiplatelet agents, related to ischemic end points, all-cause death, cardiovascular events, and cardiac death. A C-index of >0.7 and the calibration curve demonstrated good concordance. In a subsequent analysis, we used the all-cause death model to stratify patients by risk level, and compared the effects of clopidogrel and ticagrelor. In the subgroup with a 2-year death rate of >50%, ticagrelor showed a positive effect (P = 0.045), but in the subgroup with a 2-year death rate of <50%, the difference between clopidogrel and ticagrelor was not significant. Considering the duration of effect of antiplatelet agents, we also compared these 2 agents at 1-year follow up, with ticagrelor showing no advantage. IMPLICATIONS: We determined the probability of ischemic risk in patients at extremely high ischemic risk and developed new risk models for this specific group. Ticagrelor, compared with clopidogrel, may improve the prognosis of patients at high risk for death after 2 years.

Prognostic impact of light-chain and transthyretin-related categories in cardiac amyloidosis: A systematic review and meta-analysis.

OBJECTIVE: Light-chain amyloidosis and transthyretin-related amyloidosis (wild-type and mutated) are three main types of systemic amyloidosis associated with a clinically relevant cardiac involvement. In this study, we compared prognosis in patients with different categories of cardiac amyloidosis using meta-analysis and present a systematic review. METHODS: A systematic literature search was performed through Jan 1, 2018, and two reviewers independently extracted data and assessed risk of bias. We extracted MACE and death endpoint events and hazard ratios from regression models and performed a meta-analysis of the multiple prognosis association studies. RESULTS: We observed that there were significant MACE differences between patients diagnosed with transthyretin amyloidosis and light-chain amyloidosis (OR: 2.09; 95% CI: 1.06-4.12; P = 0.03), and the same is true in the sub-comparison between AL and mATTR or wtATTR (AL vs. mATTR: OR: 1.72; 95% CI: 1.06-2.82; P = 0.03; AL vs. wtATTR: OR: 1.48; 95% CI: 0.85-2.58; P = 0.17). However, no significant difference was observed between two transthyretin types (P = 0.17). Overall death rate evaluated showed that compared with transthyretin-related amyloidosis, light-chain type showed a significant difference (P < 0.05). The prognostic analysis showed that types of amyloidosis, LVEF, NYHA, restrictive filling pattern, E-wave deceleration time, E/E' ratio, and low QRS voltage were predictors of cardiac-related mortality. CONCLUSION: Patients diagnosed with light-chain amyloidosis has a poor prognosis compared with transthyretin-related amyloidosis, while no difference was proved in prognostic analysis between wild-type and mutated TTR amyloidosis. Some clinical factors related to the death prognosis, such as the LVEF, restrictive filling pattern, E-wave deceleration time, and E/E' ratio are important prognostic factors.

Tafamidis, a Noninvasive Therapy for Delaying Transthyretin Familial Amyloid Polyneuropathy: Systematic Review and Meta-Analysis.

BACKGROUND AND PURPOSE: Tafamidis functions to delay the loss of function in transthyretin familial amyloid polyneuropathy (TTR-FAP), which is a rare inherited amyloidosis with progressive sensorimotor and autonomic polyneuropathy. This systematic literature review and meta-analysis evaluated the efficacy and safety of tafamidis in TTR-FAP patients, with the aim of improving the evidence-based medical evidence of this treatment option for TTP-FAP. METHODS: A systematic search of the English-language literature in five databases was performed through to May 31, 2018 by two reviewers who independently extracted data and assessed the risk of bias. We extracted efficacy and safety outcomes and performed a meta-analysis. Statistical tests were performed to check for heterogeneity and publication bias. RESULTS: The meta-analysis identified six relevant studies. The tafamidis group showed smaller changes from baseline in the Neuropathy Impairment Score-Lower Limbs [mean difference (MD)=-3.01, 95% confidence interval (CI)=-3.26 to -2.75, p<0.001] and the Norfolk Quality of Life-Diabetic Neuropathy total quality of life score (MD=-6.67, 95% CI=-9.70 to -3.64, p<0.001), and a higher modified body mass index (MD=72.45, 95% CI=69.41 to 75.49, p<0.001), with no significant difference in total adverse events [odds ratio (OR)=0.69, 95% CI=0.35 to 1.35, p=0.27]. The incidence of adverse events did not differ between tafamidis and placebo treatment except for fatigue (OR=0.13, 95% CI=0.02 to 0.72, p=0.02) and hypesthesia (OR=0.16, 95% CI=0.03 to 0.92, p=0.04). CONCLUSIONS: This systematic review and meta-analysis has demonstrated that tafamidis delays neurologic progression and preserves a better nutritional status and the quality of life. The rates of adverse events did not differ between the patients in the tafamidis and placebo groups. Tafamidis might be a safer noninvasive option for patients with TTR-FAP.

Efficacy and safety of ticagrelor versus clopidogrel with different dosage in high-risk patients with acute coronary syndrome.

BACKGROUND: Dual antiplatelet therapy is recommended as a standard antiplatelet strategy in acute coronary syndrome. For those with reduced pharmacologic response to clopidogrel, strengthening antiplatelet therapy (clopidogrel 150mg daily) may reduce adverse clinical events. Ticagrelor is a direct-acting inhibitor of the adenosine diphosphate receptor P2Y12 that has a more rapid onset and offset than clopidogrel. METHODS: In this retrospective study, we compared ticagrelor (180mg loading dose 90mg twice daily thereafter), clopidogrel (300mg loading dose, 75mg or 150mg daily thereafter) for the prevention of cardiovascular events in 273 high-risk patients admitted to coronary care unit with acute coronary syndrome. RESULTS: The rate of IST in hospital was significantly reduced in patients of ticagrelor group comparing with those receiving clopidogrel 75mg (0.69% vs 8.2%, p=0.009). Moreover, the TVR rate was less in the ticagrelor group than clopidogrel 75mg group (2.7% vs 13.1%, p=0.007) 6months follow-up. The incidence of MACCE has no difference between the two clopidogrel groups. Kaplan-Meier analysis of MACCE-free indicated that there was no difference between the three groups. Ticagrelor significantly increased the rate of minor bleeding compared with clopidogrel 75mg daily during hospital (45.5% vs 26.2%,p=0.012) and 6-month follow-up (66.9% vs 45.9%,p=0.004).Bleeding-free prognosis was significantly better in the clopidogrel 75mg daily group. CONCLUSIONS: In patients with acute coronary syndrome undergoing PCI, the rate of in-stent thrombosis and TVR were significantly reduced treated with ticagrelor compared with clopidogrel 75mg daily, without an increase of overall major bleeding, but with an increase of minor bleeding.