Project description:Despite significant improvements in morbidity and mortality with current evidence-based pharmaceutical-based treatment of heart failure (HF) over the previous decades, the burden of HF remains high. An alternative approach is currently being developed, which targets myocardial energy efficiency and the dysfunction of the cardiac mitochondria. Emerging evidence suggests that the insufficient availability of ATP to the failing myocardium can be attributed to abnormalities in the myocardial utilisation of its substrates rather than an overall lack of substrate availability. Therefore, the development of potential metabolic therapeutics has commenced including trimetazidine, ranolazine and perhexiline, as well as specific mitochondrial-targeting pharmaceuticals, such as elamipretide. Large randomised controlled trials are required to confirm the role of metabolic-modulating drugs in the treatment of heart failure, but early studies have been promising in their possible efficacy for the management of heart failure in the future.
Project description:BackgroundMyocardial mitochondrial dysfunction is the leading cause of chronic heart failure (CHF). Increased reactive oxygen species (ROS) levels, disruption of mitochondrial biogenesis and mitochondrial Ca2+([Ca2+]m) homeostasis and reduction of the mitochondrial membrane potential (ΔΨm) cause myocardial mitochondrial dysfunction. Therefore, treating CHF by targeting mitochondrial function is a focus of current research. For the first time, this study investigated the effects of the strong antioxidant pyrroloquinoline quinone (PQQ) on mitochondrial function in a cardiac pressure overload model, and the mechanism by which PQQ regulates [Ca2+]m homeostasis was explored in depth.MethodsAfter transaortic constriction (TAC), normal saline and PQQ (0.4, 2 and 10 mg/kg) were administered intragastrically to Sprague Dawley (SD) rats for 12 weeks. In vitro, neonatal rat left ventricle myocytes (NRVMs) were pretreated with 200 nm angiotensin II (Ang II) with or without PQQ (1, 10 and 100 μM). Rat heart remodelling was verified by assessment of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels (qRT-PCR), cell surface area (wheat germ agglutinin (WGA) staining in vivo and α-actin in vitro) and echocardiography. Myocardial mitochondrial morphology was assessed by transmission electron microscopy. Western blotting was used to assess mitochondrial biogenesis [peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and transcription factor A, mitochondrial (TFAM)]. The ΔΨm was determined by tetraethyl benzimidazolyl carbocyanine iodide (JC-1) staining and flow cytometry, and ROS levels were measured by dichloro-dihydro-fluorescein diacetate (DCFH-DA) and MitoSOX Red staining. [Ca2+]m was measured by isolating rat mitochondria, and mitochondrial Ca2+ channel proteins [the mitochondrial Na+/Ca2+ exchanger (NCLX) and mitochondrial Ca2+ uniporter (MCU)] were detected by Western blot.ResultsIn vivo and in vitro, PQQ pretreatment improved pressure overload-induced cardiac remodelling and cell hypertrophy, thus preventing the occurrence of CHF. PQQ also prevented mitochondrial morphology damage and reduced the PGC-1α and TFAM downregulation caused by TAC or Ang II. In addition, in NRVMs treated with Ang II + PQQ, PQQ regulated ROS levels and increased the ΔΨm. PQQ also regulated [Ca2+]m homeostasis and prohibited [Ca2+]m overloading by increasing NCLX expression.ConclusionsThese results show that PQQ can prevent [Ca2+]m overload by increasing NCLX expression and thereby reducing ROS production and protecting the ΔΨm. At the same time, PQQ can increase PGC-1α and TFAM expression to regulate mitochondrial biogenesis. These factors can prevent mitochondrial dysfunction, thereby reducing cardiac damage caused by pressure overload and preventing the occurrence of CHF.
Project description:Mitochondrial dysfunction characterized by impaired bioenergetics, oxidative stress and aldehydic load is a hallmark of heart failure. Recently, different research groups have provided evidence that selective activation of mitochondrial detoxifying systems that counteract excessive accumulation of ROS, RNS and reactive aldehydes is sufficient to stop cardiac degeneration upon chronic stress, such as heart failure. Therefore, pharmacological and non-pharmacological approaches targeting mitochondria detoxification may play a critical role in the prevention or treatment of heart failure. In this review we discuss the most recent findings on the central role of mitochondrial dysfunction, oxidative stress and aldehydic load in heart failure, highlighting the most recent preclinical and clinical studies using mitochondria-targeted molecules and exercise training as effective tools against heart failure.
Project description:We conducted RNAseq using mRNA extracted from rat hearts to elucidate the effect of doxorubicin chemotherapy on the heart. Rats were 250g at the start of the treatment protocol. Tissues were collected post five weekly intravenous injections of either sterile saline or 3mg/kg/week doxorubicin. Hearts were excised under deep isoflurane anaesthesia and rapidly frozen with liquid-nitrogen cooled Wallenberger tongs. Total mRNA was extracted with a Qiagen RNeasy fibrous tissue mini kit. Gene set enrichement analysis (GSEA) shows that unlike previously reported, oxidative stress is not involved in the cardiac pathology of our model (reduced cardiac function and atrophy). However, gene sets responsible for mRNA processing, ribosomes and protein synthesis and processing are decreased in doxorubicin-treated rat hearts compared to saline control hearts.
Project description:AimsWe previously demonstrated that pharmacological activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2) protects the heart against acute ischaemia/reperfusion injury. Here, we determined the benefits of chronic activation of ALDH2 on the progression of heart failure (HF) using a post-myocardial infarction model.Methods and resultsWe showed that a 6-week treatment of myocardial infarction-induced HF rats with a selective ALDH2 activator (Alda-1), starting 4 weeks after myocardial infarction at a time when ventricular remodelling and cardiac dysfunction were present, improved cardiomyocyte shortening, cardiac function, left ventricular compliance and diastolic function under basal conditions, and after isoproterenol stimulation. Importantly, sustained Alda-1 treatment showed no toxicity and promoted a cardiac anti-remodelling effect by suppressing myocardial hypertrophy and fibrosis. Moreover, accumulation of 4-hydroxynonenal (4-HNE)-protein adducts and protein carbonyls seen in HF was not observed in Alda-1-treated rats, suggesting that increasing the activity of ALDH2 contributes to the reduction of aldehydic load in failing hearts. ALDH2 activation was associated with improved mitochondrial function, including elevated mitochondrial respiratory control ratios and reduced H2O2 release. Importantly, selective ALDH2 activation decreased mitochondrial Ca(2+)-induced permeability transition and cytochrome c release in failing hearts. Further supporting a mitochondrial mechanism for ALDH2, Alda-1 treatment preserved mitochondrial function upon in vitro aldehydic load.ConclusionsSelective activation of mitochondrial ALDH2 is sufficient to improve the HF outcome by reducing the toxic effects of aldehydic overload on mitochondrial bioenergetics and reactive oxygen species generation, suggesting that ALDH2 activators, such as Alda-1, have a potential therapeutic value for treating HF patients.
Project description:PURPOSE OF REVIEW:We highlight the unique properties of the sodium-glucose cotransporter-2 (SGLT-2 inhibitors) which may lend favorably to their efficient integration in the background of other heart failure (HF) therapies. We also discuss the unique aspects of SGLT-2 inhibitor dosing, lack of titration needs, effects on kidney function and electrolytes, diuretic activity, and safety in the high-risk peri-hospitalization window. RECENT FINDINGS:Dapagliflozin was recently approved for the treatment of heart failure with reduced ejection fraction (HFrEF), irrespective of the presence or absence of type 2 diabetes mellitus (T2DM) based on the findings of the pivotal DAPA-HF trial. All SGLT-2 inhibitors are once daily medications with minimal drug-drug interactions and do not require titration (for HF treatment) unlike other HF medications. SGLT-2 inhibitors offer modest weight loss and blood pressure reduction without major adverse effects of hyperkalemia, making it ideal for near-simultaneous initiation with other HF medications, and use in high-risk populations (including older adults). Moreover, SGLT-2 inhibitors appear to afford long-term kidney protection in diverse populations. SGLT-2 inhibitors are the latest class of therapies to demonstrate important clinical benefits among patients with HFrEF, and their pharmacological properties favor ease of use and integration in multi-drug disease-modifying regimens.
Project description:BackgroundElamipretide (MTP-131), a novel mitochondria-targeting peptide, was shown to reduce infarct size in animals with myocardial infarction and improve renal function in pigs with acute and chronic kidney injury. This study examined the effects of chronic therapy with elamipretide on left ventricular (LV) and mitochondrial function in dogs with heart failure (HF).Methods and resultsFourteen dogs with microembolization-induced HF were randomized to 3 months monotherapy with subcutaneous injections of elamipretide (0.5 mg/kg once daily, HF+ELA, n=7) or saline (control, HF-CON, n=7). LV ejection fraction, plasma n-terminal pro-brain natriuretic peptide, tumor necrosis factor-α, and C-reactive protein were measured before (pretreatment) and 3 months after initiating therapy (post-treatment). Mitochondrial respiration, membrane potential (Δψm), maximum rate of ATP synthesis, and ATP/ADP ratio were measured in isolated LV cardiomyocytes obtained at post-treatment. In HF-CON dogs, ejection fraction decreased at post-treatment compared with pretreatment (29 ± 1% versus 31 ± 2%), whereas in HF+ELA dogs, ejection fraction significantly increased at post-treatment compared with pretreatment (36 ± 2% versus 30 ± 2%; P<0.05). In HF-CON, n-terminal pro-brain natriuretic peptide increased by 88 ± 120 pg/mL during follow-up but decreased significantly by 774 ± 85 pg/mL in HF+ELA dogs (P<0.001). Treatment with elamipretide also normalized plasma tumor necrosis factor-α and C-reactive protein and restored mitochondrial state-3 respiration, Δψm, rate of ATP synthesis, and ATP/ADP ratio (ATP/ADP: 0.38 ± 0.04 HF-CON versus 1.16 ± 0.15 HF+ELA; P<0.001).ConclusionsLong-term therapy with elamipretide improves LV systolic function, normalizes plasma biomarkers, and reverses mitochondrial abnormalities in LV myocardium of dogs with advanced HF. The results support the development of elamipretide for the treatment of HF.
Project description:AimsMitochondrial fusion and fission are essential processes for preservation of normal mitochondrial function. We hypothesized that fusion proteins would be decreased in heart failure (HF), as the mitochondria in HF have been reported to be small and dysfunctional.Methods and resultsExpression of optic atrophy 1 (OPA1), a mitochondrial fusion protein, was decreased in both human and rat HF, as observed by western blotting. OPA1 is important for maintaining normal cristae structure and function, for preserving the inner membrane structure and for protecting cells from apoptosis. Confocal and electron microscopy studies demonstrated that the mitochondria in the failing hearts were small and fragmented, consistent with decreased fusion. OPA1 mRNA levels did not differ between failing and normal hearts, suggesting post-transcriptional control. Simulated ischaemia in the cardiac myogenic cell line H9c2 cells reduced OPA protein levels. Reduction of OPA1 expression with shRNA resulted in increased apoptosis and fragmentation of the mitochondria. Overexpression of OPA1 increased mitochondrial tubularity, but did not protect against simulated ischaemia-induced apoptosis. Cytochrome c release from the mitochondria was increased both with reduction in OPA1 and with overexpression of OPA1.ConclusionThis is the first report, to our knowledge, of changes in mitochondrial fusion/fission proteins in cardiovascular disease. These changes have implications for mitochondrial function and apoptosis, contributing to the cell loss which is part of the downward progression of the failing heart.