Combined statin/coenzyme Q10 as adjunctive treatment of chronic heart failure

Iron Dyshomeostasis and Mitochondrial Function in the Failing Heart: A Review of the Literature

Cardiac contraction and relaxation require a substantial amount of energy provided by the mitochondria. The failing heart is adenosine triphosphate (ATP)- and creatine-depleted. Studies have found iron is involved in almost every aspect of mitochondrial function, and previous studies have shown myocardial iron deficiency in heart failure (HF). Many clinicians advocated intravenous iron repletion for HF patients meeting the conventional criteria for systemic iron deficiency. While clinical trials showed improved quality of life, iron repletion failed to significantly impact survival or significant cardiovascular adverse events. There is evidence that in HF, labile iron is trapped inside the mitochondria causing oxidative stress and lipid peroxidation. There is also compelling preclinical evidence demonstrating the detrimental effects of both iron overload and depletion on cardiomyocyte function. We reviewed the mechanisms governing myocardial and mitochondrial iron content. Mitochondrial dynamics (i.e., fusion, fission, mitophagy) and the role of iron were also investigated. Ferroptosis, as an important regulated cell death mechanism involved in cardiomyocyte loss, was reviewed along with agents used to manipulate it. The membrane stability and iron content of mitochondria can be altered by many agents. Some studies are showing promising improvement in the cardiomyocyte function after iron chelation by deferiprone; however, whether the in vitro and in vivo findings will be reflected on on clinical grounds is still unclear. Finally, we briefly reviewed the clinical trials on intravenous iron repletion. There is a need for more well-simulated animal studies to shed light on the safety and efficacy of chelation agents and pave the road for clinical studies.

Improving mitochondrial function in preclinical models of heart failure: therapeutic targets for future clinical therapies?

INTRODUCTION

Heart failure is a complex clinical syndrome resulting from the unsuccessful compensation of symptoms of myocardial damage. Mitochondrial dysfunction is a process that occurs because of an attempt to adapt to the disruption of metabolic and energetic pathways occurring in the myocardium. This, in turn, leads to further dysfunction in cardiomyocyte processes. Currently, many therapeutic strategies have been implemented to improve mitochondrial function, but their effectiveness varies widely.

AREAS COVERED

This review focuses on new models of therapeutic strategies targeting mitochondrial function in the treatment of heart failure.

EXPERT OPINION

Therapeutic strategies targeting mitochondria appear to be a valuable option for treating heart failure. Currently, the greatest challenge is to develop new research models that could restore the disrupted metabolic processes in mitochondria as comprehensively as possible. Only the development of therapies that focus on improving as many dysregulated mitochondrial processes as possible in patients with heart failure will be able to bring the expected clinical improvement, along with inhibition of disease progression. Combined strategies involving the reduction of the effects of oxidative stress and mitochondrial dysfunction, appear to be a promising possibility for developing new therapies for a complex and multifactorial disease such as heart failure.

A Review of the Role of Statins in Heart Failure Treatment

BACKGROUND

Heart failure is a common medical problem in the world, which has a high prevalence in both developed and developing countries. Today, among the medications used for the heart failure treatment, there are many medications with a positive cardiac contraction effect (positive inotropic such as digital glycosides, adrenergic receptor stimulants, and phosphodiesterase inhibitors), a large number of cardiac diluents (such as Angiotensin-Converting Enzyme (ACE) inhibitor group), and a few other types of drugs whose final effects are still under review. Statins are valuable drugs that are broadly prescribed in hyperlipidemia and cardiovascular patients due to their multiple properties, such as cholesterol reduction, endothelial function improvement, antioxidative, anti-inflammatory, neovascularization, and immunomodulatory activities.

METHODS

There is evidence that the therapeutic role of statins in HF, due to myocardial hypertrophy, show reduction in cardiomyocyte loss in the apoptosis process, oxidative stress, inflammation, and also the return of neurohormonal imbalance. However, the fact that these drugs have no sideeffects has not been confirmed in all studies, as statins prevent the production of particular beneficial and protective factors, such as coenzyme Q10 (CoQ10), while inhibiting the production of specific proteins involved in pathologic mechanisms.

RESULTS

Recently, it has been hypothesized that, despite the positive effects reported, high doses of statins in patients with long-term heart failure lead to progress in heart failure by inhibiting CoQ10 synthesis and intensifying hypertrophy.

CONCLUSION

Thus, it can be stated that the advantage of using statins depends on factors, such as stroke fraction, and the existence of other standard indications such as atherosclerotic diseases or high Low-Density Lipoprotein-C (LDL-C).

CoenzymeQ in cellular redox regulation and clinical heart failure

Coenzyme Q (CoQ) is ubiquitously embedded in lipid bilayers of various cellular organelles. As a redox cycler, CoQ shuttles electrons between mitochondrial complexes and extramitochondrial reductases and oxidases. In this way, CoQ is crucial for maintaining the mitochondrial function, ATP synthesis, and redox homeostasis. Cardiomyocytes have a high metabolic rate and rely heavily on mitochondria to provide energy. CoQ levels, in both plasma and the heart, correlate with heart failure in patients, indicating that CoQ is critical for cardiac function. Moreover, CoQ supplementation in clinics showed promising results for treating heart failure. This review provides a comprehensive view of CoQ metabolism and its interaction with redox enzymes and reactive species. We summarize the clinical trials and applications of CoQ in heart failure and discuss the caveats and future directions to improve CoQ therapeutics.

Therapeutic implications of statins in heart failure with reduced ejection fraction and heart failure with preserved ejection fraction: a review of current literature

Statins are one of the standard treatments to prevent cardiovascular events such as coronary artery disease and heart failure (HF). However, data on the use of statins to improve clinical outcomes in patients with established HF remains controversial. We summarized available clinical studies which investigated the effects of statins on clinical outcomes in patients with HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Statins possess many pleiotropic effects in addition to lipid-lowering properties that positively affect the pathophysiology of HF. In HFrEF, data from two large randomized placebo-controlled trials did not show benefits of statins on mortality of patients with HFrEF. However, more recent prospective cohort studies and meta-analyses have shown decreased risk of mortality as well as cardiovascular hospitalization with statins treatment. In HFpEF, most prospective and retrospective cohort studies as well as meta analyses have consistently reported positive effects of statins, including reducing mortality and improving other clinical outcomes. Current evidence also suggests better outcomes with lipophilic statins in patients with HF. In summary, statins might be effective in improving survival and other clinical outcomes in patients with HF, especially for patients with HFpEF. Lipophilic statins might also be more beneficial for HF patients. Based on current evidence, statins did not cause harm and should be continued in HF patients who are already taking the medication. Further randomized controlled trials are needed to clarify the benefits of statins in HF patients.

Role of N-Acetylcysteine and Coenzyme Q10 in the Amelioration of Myocardial Energy Expenditure and Oxidative Stress, Induced by Carbon Tetrachloride Intoxication in Rats

This study is designed to evaluate the potential impact of N-acetyl cysteine (NAC) and coenzyme Q10 (CoQ10) each alone or in combination against carbon tetrachloride (CCl4)-induced cardiac damage in rats. Animals were treated with CCl4 in single intraperitoneal dose of 1 mL/Kg body weight; CCl4-intoxicated animals were pretreated with 20 mg/kg/d NAC or pretreated with 200 mg/kg/d CoQ10 or NAC and CoQ10 with the same previously mentioned doses. Carbon tetrachloride-intoxicated rats showed a significant elevation in nitric oxide and lipid peroxides and downregulation in reduced glutathione level and calcium adenosine triphosphatase. Cardiac glycolytic enzymes levels such as lactate dehydrogenase, phosphofructokinase, and hexokinase were declined coupled with a reduction in glucose content after CCl4 treatment. Moreover, myocardial hydroxyproline level was significantly increased after CCl4-treatment indicating accumulation of interstitial collagen. N-acetyl cysteine and/or CoQ10 effectively alleviated the disturbances in myocardial oxidative stress and antioxidant markers. These antioxidants effectively upregulated the reduction in cardiac energetic biomarkers due to CCl4 treatment. N-acetyl cysteine and/or CoQ10 significantly decreased hydroxyproline level compared to that of CCl4-treated rats. The current data showed that the aforementioned antioxidants have a remarkable cardioprotective effect, suggesting that they may be useful as prophylactic agents against the detrimental effects of cardiotoxins.

The mitochondrial unfolded protein response activator ATFS-1 protects cells from inhibition of the mevalonate pathway

Statins are cholesterol-lowering drugs that inhibit 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, the rate-limiting enzyme in the synthesis of cholesterol via the mevalonate pathway. This pathway also produces coenzyme Q (a component of the respiratory chain), dolichols (important for protein glycosylation), and isoprenoids (lipid moieties responsible for the membrane association of small GTPases). We previously showed that the nematode Caenorhabditis elegans is useful to study the noncholesterol effects of statins because its mevalonate pathway lacks the sterol synthesis branch but retains all other branches. Here, from a screen of 150,000 mutagenized genomes, we isolated four C. elegans mutants resistant to statins by virtue of gain-of-function mutations within the first six amino acids of the protein ATFS-1, the key regulator of the mitochondrial unfolded protein response that includes activation of the chaperones HSP-6 and HSP-60. The atfs-1 gain-of-function mutants are also resistant to ibandronate, an inhibitor of an enzyme downstream of HMG-CoA reductase, and to gliotoxin, an inhibitor acting on a subbranch of the pathway important for protein prenylation, and showed improved mitochondrial function and protein prenylation in the presence of statins. Additionally, preinduction of the mitochondrial unfolded protein response in wild-type worms using ethidium bromide or paraquat triggered statin resistance, and similar observations were made in Schizosaccharomyces pombe and in a mammalian cell line. We conclude that statin resistance through maintenance of mitochondrial homeostasis is conserved across species, and that the cell-lethal effects of statins are caused primarily through impaired protein prenylation that results in mitochondria dysfunction.

BMSC and CoQ10 improve behavioural recovery and histological outcome in rat model of Parkinson's disease

OBJECTIVE

This study assessed the ability of a combination treatment of bone marrow stromal cell (BMSC) graft and oral coenzyme (CoQ10) in a rat model of Parkinson's disease (PD) as an appropriate substitute for current Parkinson treatments. The combination treatment was compared to sole treatments of BMSC and CoQ10.

MATERIALS AND METHODS

In this experimental study, there were six groups of male Wistar rats: control, sham, lesion, CoQ10, graft BMSC and graft BMSC plus CoQ10. Oral administration of CoQ10 began 1 week before the PD and continued during the entire treatment period. To simulate PD, we injected 6 hydroxydopamine (6OHDA) in rats. BMSC were labelled by 5-bromo-2'-deoxyuridine (Brdu) before transplantation. We assessed behaviour before PD, 2 weeks after PD and 8 weeks after cell transplantation. At the end of the second month of treatment, immunohistochemistry, histology and molecular studies were performed.

RESULTS

Behavioural assessment of the CoQ10 group and BMSC group indicated equal recovery in comparison with the lesion group (P<0.01), while the combined treatment of BMSC and CoQ10 showed considerably better recovery compared with the lesion group (P<0.001). There were no signs of gliosis and graft rejection. Immunohistochemistry analysis of Brdu indicated that cells were alive after 2 months of application in host tissue. Cell counts showed significantly greater numbers of neural cells in the combination treatment of BMSC and CoQ10 compared to the other groups. Tyrosine hydroxylase (TH) gene expression levels in the combined therapy group was significantly more than the other experimental groups (P<0.001).

CONCLUSION

The combined use of two neuroprotective treatments and cell replacement therapy can be effective in the treatment of PD, at least in experimental settings.

Epidemiology and etiology of Parkinson's disease: a review of the evidence

The etiology of Parkinson's disease (PD) is not well understood but likely to involve both genetic and environmental factors. Incidence and prevalence estimates vary to a large extent-at least partly due to methodological differences between studies-but are consistently higher in men than in women. Several genes that cause familial as well as sporadic PD have been identified and familial aggregation studies support a genetic component. Despite a vast literature on lifestyle and environmental possible risk or protection factors, consistent findings are few. There is compelling evidence for protective effects of smoking and coffee, but the biologic mechanisms for these possibly causal relations are poorly understood. Uric acid also seems to be associated with lower PD risk. Evidence that one or several pesticides increase PD risk is suggestive but further research is needed to identify specific compounds that may play a causal role. Evidence is limited on the role of metals, other chemicals and magnetic fields. Important methodological limitations include crude classification of exposure, low frequency and intensity of exposure, inadequate sample size, potential for confounding, retrospective study designs and lack of consistent diagnostic criteria for PD. Studies that assessed possible shared etiological components between PD and other diseases show that REM sleep behavior disorder and mental illness increase PD risk and that PD patients have lower cancer risk, but methodological concerns exist. Future epidemiologic studies of PD should be large, include detailed quantifications of exposure, and collect information on environmental exposures as well as genetic polymorphisms.