Oxidative damage of DNA, RNA and their metabolites in leukocytes, plasma and urine of Macaca mulatta: 8-oxoguanosine in urine is a useful marker for aging

The levels of the oxidised forms of guanosine in leukocytes, plasma and urine of Macaca mulatta were determined using a sensitive method based on high-performance liquid chromatography-triple quadruple mass spectrometry (LC-MS/MS). The amounts of 8-oxo-7,8-dihydrodeoxyguanosine (8-oxo-dGsn) and 8-oxo-7,8-dihydroguanosin (8-oxoGsn), derived from DNA and RNA, respectively, increased with age in leukocytes. The measurement of the free forms of oxidised guanosine revealed similar age-dependent increases of 8-oxo-dGsn and 8-oxoGsn in both plasma and urine, which showed considerably larger amounts of 8-oxoGsn than 8-oxo-dGsn. The 8-oxoGsn content of urine could be a useful biomarker for evaluating aging, as age-dependent increases of 8-oxoGsn are more evident in urine compared to plasma and because urine samples are readily available.     

Diagnostic Accuracy of NT-ProBNP for Heart Failure with Sepsis in Patients Younger than 18 Years

This clinical study investigated plasma NT-proBNP levels as a potential predictor of heart failure in pediatric patients with sepsis. Plasma NT-ProBNP levels of 211 pediatric patients with sepsis and 126 healthy children were measured. Patients were stratified as with heart failure (HF) or without heart failure (non-HF). Patients were graded as having sepsis, severe sepsis, or septic shock. The optimal cut-off values of plasma NT-ProBNP for heart failure were determined by analyzing the receiver operating characteristic (ROC). In the HF, non-HF and control groups, the median plasma NT-proBNP levels were 3640, 656, and 226 ng/L, respectively. For all patients with sepsis, the optimal diagnostic cut-off value was 1268 ng/L for differentiating heart failure. In the severe sepsis patients and septic shock patients, the optimal diagnostic cut-off values were 1368 ng/L and 1525 ng/L, respectively. This report is the first one to reveal that NT-proBNP may predict heart failure in children with sepsis. It provides an important clinical reference for the diagnosis of heart failure in pediatric patients with sepsis, and enables monitoring septic children for cardiac involvement.     

Brain angiotensin-converting enzyme activity and autonomic regulation in heart failure

Several recent studies suggest an important role for the brain renin-angiotensin system in the pathogenesis of heart failure. Angiotensin-converting enzyme (ACE) activity and binding of angiotensin type 1 (AT1) receptors, which mediate the central effects of ANG II, are increased in heart failure. The present study examined the relationship between brain ACE activity and the autonomic dysregulation characteristic of rats with congestive heart failure. Rats with heart failure (HF) induced by coronary artery ligation and sham-operated control (SHAM) rats were treated with chronic (28 days) third cerebral ventricle [intracerebroventricular (ICV)] or intraperitoneal (IP) infusion of a low dose of the ACE inhibitor enalaprilat (ENL) or vehicle (VEH). VEH-treated HF rats had increased sodium consumption, reduced urine sodium and urine volume, and increased sympathetic nerve activity with impaired baroreflex regulation. These responses were minimized or prevented by ICV ENL started 24 h after coronary ligation. IP ENL at the low dose used in these studies had no beneficial effects on HF rats. Neither IP nor ICV ENL had any substantial effect on the SHAM rats. The findings confirm a critically important contribution of the brain renin-angiotensin system to the pathophysiology of congestive heart failure.     

Prevention of cardiac hypertrophy and heart failure by silencing of NF-kappaB

Activation of the nuclear factor (NF)-κB signaling pathway may be associated with the development of cardiac hypertrophy and its transition to heart failure (HF). The transgenic Myo-Tg mouse develops hypertrophy and HF as a result of overexpression of myotrophin in the heart associated with an elevated level of NF-κB activity. Using this mouse model and an NF-κB-targeted gene array, we first determined the components of NF-κB signaling cascade and the NF-κB-linked genes that are expressed during the progression to cardiac hypertrophy and HF. Second, we explored the effects of inhibition of NF-κB signaling events by using a gene knockdown approach: RNA interference through delivery of a short hairpin RNA against NF-κB p65 using a lentiviral vector (L-sh-p65). When the short hairpin RNA was delivered directly into the hearts of 10-week-old Myo-Tg mice, there was a significant regression of cardiac hypertrophy, associated with a significant reduction in NF-κB activation and atrial natriuretic factor expression. Our data suggest, for the first time, that inhibition of NF-κB using direct gene delivery of sh-p65 RNA results in regression of cardiac hypertrophy. These data validate NF-κB as a therapeutic target to prevent hypertrophy/HF.     

3,3-Dimethyl-1-butanol attenuates cardiac remodeling in pressure-overload-induced heart failure mice

Trimethylamine N-oxide (TMAO) is closely related to cardiovascular diseases, particularly heart failure (HF). Recent studies shows that 3,3-dimethyl-1-butanol (DMB) can reduce plasma TMAO levels. However, the role of DMB in overload-induced HF is not well understood. In this research study, we explored the effects and the underlying mechanisms of DMB in overload-induced HF. Aortic banding (AB) surgery was performed in C57BL6/J mice to induce HF, and a subset group of mice underwent a sham operation. After surgery, the mice were fed with a normal diet and given water supplemented with or without 1% DMB for 6 weeks. Cardiac function, plasma TMAO level, cardiac hypertrophy and fibrosis, expression of inflammatory, electrophysiological studies and signaling pathway were analyzed at the sixth week after AB surgery. DMB reduced TMAO levels in overload-induced HF mice. Adverse cardiac structural remodeling, such as cardiac hypertrophy, fibrosis and inflammation, was elevated in overload-induced HF mice. Susceptibility to ventricular arrhythmia also significantly increased in overload-induced HF mice. However, these changes were prevented by DMB treatment. DMB attenuated all of these changes by reducing plasma TMAO levels, hence negatively inhibiting the p65 NF-κB signaling pathway and TGF-β1/Smad3 signaling pathway. DMB plays an important role in attenuating the development of cardiac structural remodeling and electrical remodeling in overload-induced HF mice. This may be attributed to the p65 NF-κB signaling pathway and TGF-β1/Smad3 signaling pathway inhibition.     

Oxidative damage to RNA and expression patterns of MTH1 in the hippocampi of senescence-accelerated SAMP8 mice and Alzheimer's disease patients

Mammalian MTH1 protein, a MutT-related protein, catalyzes the hydrolysis of 8-oxo-7,8-dihydroguanosine triphosphate (8-oxoGTP) to monophosphate, thereby preventing incorporation of 8-oxo-7,8-dihydroguanine (8-oxoguanine) into RNA. In this study, we applied immunohistochemistry to follow the expression of MTH1 and the amount of 8-oxoguanine in RNA during aging. There were increased amounts of 8-oxoguanine in RNA in the CAl and CA3 subregions of hippocampi of 8- and 12-month-old SAMP8 mice, which exhibited early aging syndromes and declining learning and memory abilities compared to those of age-matched control SAMR1 mice. The expression levels of MTH1 in the hippocampi of 8- and 12-month-old SAMP8 mice were significantly lower than those of control mice. Therefore, in this mouse model, age-related accumulation of 8-oxoguanine in RNA is correlated with decreased expression of MTH1. Increased amounts of 8-oxoguanine in the RNA, and decreased expression of MTH1 were also observed in the hippocampi of patients suffering from Alzheimer’s disease. These results suggest that MTH1 deficiency might be a causative factor for aging and age-related disorders.     

Manifestations and Mechanism of SARS-CoV2 Mediated Cardiac Injury

Coronavirus disease 2019 (COVID-19), a global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) had resulted in considerable morbidity and mortality. COVID-19 primarily posed a threat to the respiratory system and violated many different organs, including the heart, kidney, liver, and blood vessels with the development of the disease. Severe patients were often accompanied by cardiac injury, and once the heart gets damaged, the mortality of patients will significantly increase. The main clinical manifestations of cardiac injury range from myocarditis, heart failure (HF), arrhythmia, and Takotsubo cardiomyopathy (TCM). A high abundance of angiotensin-converting enzyme II (ACE2) on the membrane of cardiomyocytes makes it possible that the virus can directly attack cardiomyocytes as subsequently evidenced by the detection of spike protein and virus RNA in autopsy cardiac tissues. The secondary myocardial injury through systemic inflammatory and immune response also caused obvious cardiac damage. The pathological manifestations of heart tissue were diverse, varied from mild cardiomyocyte edema, myocardial hypertrophy, cardiomyocyte degeneration, and necrosis to severe myocarditis caused by lymphocyte and macrophage infiltration. However, the mechanism of heart injury was still unclear. Here, we summarized the clinical manifestations and mechanism of SARS-CoV2 mediated cardiac injury, providing a reference for cardiac treatment in critically ill patients.     

Moderate severity heart failure does not involve a downregulation of myocardial fatty acid oxidation

Recent human and animal studies have demonstrated that in severe end-stage heart failure (HF), the cardiac muscle switches to a more fetal metabolic phenotype, characterized by downregulation of free fatty acid (FFA) oxidation and an enhancement of glucose oxidation. The goal of this study was to examine myocardial substrate metabolism in a model of moderate coronary microembolization-induced HF. We hypothesized that during well-compensated HF, FFA oxidation would predominate as opposed to a more fetal metabolic phenotype of greater glucose oxidation. Cardiac substrate uptake and oxidation were measured in normal dogs (n = 8) and in dogs with microembolization-induced HF (n = 18, ejection fraction = 28%) by infusing three isotopic tracers ([9,10-(3)H]oleate, [U-(14)C]glucose, and [1-(13)C]lactate) in anesthetized open-chest animals. There were no differences in myocardial substrate metabolism between the two groups. The total activity of pyruvate dehydrogenase, the key enzyme regulating myocardial pyruvate oxidation (and hence glucose and lactate oxidation) was not affected by HF. We did not observe any difference in the activity of carnitine palmitoyl transferase I (CPT-I) and its sensitivity to inhibition by malonyl-CoA between groups; however, malonyl-CoA content was decreased by 22% with HF, suggesting less in vivo inhibition of CPT-I activity. The differences in malonyl-CoA content cannot be explained by changes in the Michaelis-Menten constant and maximal velocity for malonyl-CoA decarboxylase because neither were affected by HF. These results support the concept that there is no decrease in fatty acid oxidation during compensated HF and that the downregulation of fatty acid oxidation enzymes and the switch to carbohydrate oxidation observed in end-stage HF is only a late-stage phenomenon.     

New aspects of impaired mitochondrial function in heart failure

This minireview focuses on the impairment of function in cardiac mitochondria in heart failure (HF). It is generally accepted that chronic energy starvation leads to cardiac mechanical dysfunction in HF. Mitochondria are the primary ATP generator for the heart. Current evidence suggests that the assembly of the electron transport chain (ETC) into respirasomes provides structural support for mitochondrial oxidative phosphorylation by facilitating electron channeling and perhaps by preventing electron leak and superoxide production. Defects have been purported to occur in the individual ETC complexes or components of the phosphorylation apparatus in HF, but these defects have not been linked to impaired mitochondrial function. Moreover, studies that reported decreased mitochondrial oxidative phosphorylation in HF did not identify the site of the defect. We propose a sequential mechanistic pathway in which the decrease in functional respirasomes in HF is the primary event causing decreased oxidative phosphorylation and increased reactive oxygen species production, leading to a progressive decrease in cardiac performance.     

缬沙坦氢氯噻嗪对高血压合并心力衰竭患者AngⅡ、NT-ProBNP及CTGF的作用分析

目的:探讨缬沙坦氢氯噻嗪对高血压合并心力衰竭患者血管紧张素Ⅱ(AngⅡ)、氨基末端脑钠尿肽前体(NT-ProBNP)及结蹄组织生长因子(CTGF)的作用.方法:选择2016年3月到2019年3月我院收治的高血压合并心力衰竭患者113例进行研究,以随机数表法分为观察组(n=57)和对照组(n=56).对照组给予贝那普利治...     

Genetics of heart failure

Heart failure (HF) occurs when the cardiac output, no longer compensated by endogenous mechanisms, fails to meet the metabolic demands of the body. In most populations, the prevalence of heart failure continues to rise, constituting a major public health burden, especially in developed countries. There is some evidence that the risk of HF in the general population depends on genetic predisposition, necessarily characterised by a very complex architecture. In a small, but probably underestimated proportion, HF is caused by Mendelian inherited forms of myocardial disease. The genetic background of these genetic conditions is a matter of intensive research that is already shedding light onto the genetics of common sporadic forms of HF. In this review, we briefly review the insights provided by candidate gene and genome-wide association approaches in common HF and then describe the main genetic causes of inherited heart muscle disease. Finally we present the current challenges and future research needs for both forms of HF. This article is part of a Special Issue entitled: Heart failure pathogenesis and emerging diagnostic and therapeutic interventions.     

microRNA-665 silencing improves cardiac function in rats with heart failure through activation of the cAMP signaling pathway

Heart failure (HF) is a disease with high mortality and morbidity rate. Previous studies have shown that microRNAs (miRNAs) may be implicated in the pathogenesis of HF, potentially being able to improve the cardiac function in an HF rat model. The present study was designed to define the role of miR-665 in the cardiac function of the HF rats. Following the establishm;ent of the rat models of HF, the functional role miR-665 in HF was determined using an ectopic expression and knockdown experiments. The cardiac function was evaluated with the determination of ventricular mass index and hemodynamic parameters. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining was performed, with the apoptosis of cardiac cells detected in the process. The expression of miR-665, glucagon-like peptide 1 receptor (GLP1R), cyclic adenosine monophosphate (cAMP) signaling pathway-related, and apoptosis-related genes was examined. Enzyme-linked immunosorbent assay was conducted to determine the levels of inflammation-related genes. Initially, the upregulation of miR-665, downregulation of GLP1R, and inactivation of cAMP signaling pathway were observed in HF rats. GLP1R was a target of miR-665. Forced expression of miR-665 promoted cell apoptosis and inhibited GLP1R and the cAMP signaling pathway. In addition, miR-665 overexpression has been known to impair cardiac function, promote inflammatory response while elevating malondialdehyde and superoxide dismutase levels, and decreasing mitochondrial respiratory chain enzyme activities. Furthermore, we also observed that the effects of miR-665 inhibition had been reversed when the cAMP signaling pathway was also inhibited. This study demonstrates that miR-665 inhibition can stabilize the cardiac function of HF rats via the cAMP signaling pathway via upregulation of the GLP1R.     

Pathophysiology and biochemistry of cardiovascular disease

Atherosclerosis is the major cause of cardiovascular disease. Hypercholesterolaemia, hypertension and cigarette smoking are the common risk factors for atherosclerosis. These risk factors unite behind a convergence of mechanism, involving oxidation and inflammation in the artery wall that, with time, gives rise to characteristic fatty-fibrous lesions. Physical trauma and inflammation produce lesion rupture, which can lead to clinical events such as heart attack and stroke, or resolve with plaque growth. Disease progression is marked by the inflammatory indicator CRP (C-reactive protein). Early indicators of heart attack are the inflammatory marker CD40, and the cardiac myofilament protein troponin. Coronary atherosclerosis is the common cause of heart failure (HF). Disordered calcium signalling to the myofilaments occurs in HF and in cardiomyopathy. Enhanced calcium signalling suppresses HF. Neuro-humoral and biomechanical processes, as seen in hypertension, produce cardiac hypertrophy, which predisposes to HF through apoptosis. Although in humans cardiac damage produces permanent loss of cells, because the heart cannot regenerate, developments in stem cell technology suggest that help is at hand.     

Cardiomyocyte Aldose Reductase Causes Heart Failure and Impairs Recovery from Ischemia

Aldose reductase (AR), an enzyme mediating the first step in the polyol pathway of glucose metabolism, is associated with complications of diabetes mellitus and increased cardiac ischemic injury. We investigated whether deleterious effects of AR are due to its actions specifically in cardiomyocytes. We created mice with cardiac specific expression of human AR (hAR) using the α–myosin heavy chain (MHC) promoter and studied these animals during aging and with reduced fatty acid (FA) oxidation. hAR transgenic expression did not alter cardiac function or glucose and FA oxidation gene expression in young mice. However, cardiac overexpression of hAR caused cardiac dysfunction in older mice. We then assessed whether hAR altered heart function during ischemia reperfusion. hAR transgenic mice had greater infarct area and reduced functional recovery than non-transgenic littermates. When the hAR transgene was crossed onto the PPAR alpha knockout background, another example of greater heart glucose oxidation, hAR expressing mice had increased heart fructose content, cardiac fibrosis, ROS, and apoptosis. In conclusion, overexpression of hAR in cardiomyocytes leads to cardiac dysfunction with aging and in the setting of reduced FA and increased glucose metabolism. These results suggest that pharmacological inhibition of AR will be beneficial during ischemia and in some forms of heart failure.     

Proteomics of epicardial adipose tissue in patients with heart failure

Epicardial adipose tissue (EAT) is a metabolically active visceral fat depot closely linked to the pathogenesis of heart failure (HF). But the molecular signatures related to the mechanism of HF have not been systematically explored. Here, we present comprehensive proteomic analysis of EAT in HF patients and non‐HF patients as controls. A total of 771 proteins were identified in liquid chromatography‐tandem mass spectrometry experiments. Amongst them, 17 increased in abundance in HF and seven decreased. They were involved in HF‐related processes including inflammation and oxidative stress response and lipid metabolism. Of these proteins, serine proteinase inhibitor A3 (Serpina3) levels in EAT were highly up‐regulated in HF, with HF/non‐HF ratio of 4.63 (P = .0047). Gene expression of Serpina3 via quantitative polymerase chain reaction was significantly increased in the HF group. ELISA analysis confirmed a significant increase in circulating plasma Serpina3 levels in the HF group (P = .004). In summary, for the first time, we describe that parts of EAT proteome may be reactive and work as modulators of HF. Our profiling provides a comprehensive basis for linking EAT with pathogenesis of HF. Understanding the role of EAT may offer new insights into the treatment of HF.     

Redox proteomics identification of oxidatively modified myocardial proteins in human heart failure: implications for protein function

Increased oxidative stress in a failing heart may contribute to the pathogenesis of heart failure (HF). The aim of this study was to identify the oxidised proteins in the myocardium of HF patients and analyse the consequences of oxidation on protein function. The carbonylated proteins in left ventricular tissue from failing (n?=?14) and non-failing human hearts (n?=?13) were measured by immunoassay and identified by proteomics. HL-1 cardiomyocytes were incubated in the presence of stimuli relevant for HF in order to assess the generation of reactive oxygen species (ROS), the induction of protein carbonylation, and its consequences on protein function. The levels of carbonylated proteins were significantly higher in the HF patients than in the controls (p<0.01). We identified two proteins that mainly underwent carbonylation: M-type creatine kinase (M-CK), whose activity is impaired, and, to a lesser extent, α-cardiac actin. Exposure of cardiomyocytes to angiotensin II and norepinephrine led to ROS generation and M-CK carbonylation with loss of its enzymatic activity. Our findings indicate that protein carbonylation is increased in the myocardium during HF and that these oxidative changes may help to explain the decreased CK activity and consequent defects in energy metabolism observed in HF.     

Nitric oxide generation by endothelial cells exposed to shear stress in glass tubes perfused with red blood cell suspensions: role of aggregation

When recovering from heart failure (HF), the myocardium displays a marked plasticity and can regain normal gene expression and function; however, recovery of substrate oxidation capacity has not been explored. We tested whether cardiac functional recovery is matched by normalization of energy substrate utilization during post-HF recovery. HF was induced in dogs by pacing the left ventricle (LV) at 210-240 beats/min for 4 wk. Tachycardia was discontinued, and the heart was allowed to recover. An additional group was studied in HF, and healthy dogs served as controls (n = 8/group). Cardiac free fatty acids (FFAs) and glucose oxidation were measured with [3H]oleate and [14C]glucose. At 10 days of recovery, hemodynamic parameters returned to control values; however, the contractile response to dobutamine remained depressed, LV end-diastolic volume was 28% higher than control, and the heart mass-to-body mass ratio was increased (9.8 +/- 0.4 vs. 7.5 +/- 0.2 g/kg, P < 0.05). HF increased glucose oxidation (76.8 +/- 19.7 nmol.min(-1).g(-1)) and decreased FFA oxidation (20.7 +/- 6.4 nmol.min(-1).g(-1)), compared with normal dogs (24.5 +/- 6.3 and 51.7 +/- 9.6 nmol.min(-1).g(-1), respectively), and reversed to normal values at 10 days of recovery (25.4 +/- 6.0 and 46.6 +/- 6.7 nmol.min(-1).g(-1), respectively). However, similar to HF, the recovered dogs failed to increase glucose and fatty acid uptake in response to pacing stress. The activity of myocardial citrate synthase and aconitase was significantly decreased during recovery compared with that in control dogs (58 and 27% lower, respectively, P < 0.05), indicating a persistent reduction in mitochondrial oxidative capacity. In conclusion, cardiac energy substrate utilization is normalized in the early stage of post-HF recovery at baseline, but not under stress conditions.     

Inhibition of the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway decreases DNA methylation in colon cancer cells

The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) pathway is a critical intermediary for cell proliferation, differentiation, and survival. In the human colon cancer cell line SW1116, treatment with the DNA methyltransferase 1 (DNMT1) inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) or the ERK-MAPK inhibitors PD98059 or rottlerin, or transient transfection with the MAP/ERK kinase (MEK)1/2 small interfering RNA down-regulates DNMT1 and proliferating cell nuclear antigen levels. In this report, we found that drug treatment or small interfering RNA transfection of SW1116 cells induced promoter demethylation of the p16(INK4A) and p21(WAF1) genes, which up-regulated their mRNA and protein expression levels. Flow cytometry revealed that rottlerin treatment induced cell cycle arrest at phase G(1) (p < 0.05). Thus, the ERK-MAPK inhibitor treatment or siRNA-mediated knockdown of ERK-MAPK decreases DNA methylation via down-regulating DNMT1 expression and other unknown mediator(s) in SW1116 colon cancer cells.