The Effect of Cellular Coenzyme Q10 Deficiency on Lysosomal Acidification

Therapeutic Effects of Coenzyme Q10 in the Treatment of Ischemic Stroke

PURPOSE OF REVIEW

Ischemic stroke is the second deadly disease worldwide, but current treatment is very limited. The brain, rich in lipids and high in oxygen consumption, is susceptible to damage from oxidative stress after ischemic stroke. Thus, antioxidants are promising neuroprotective agents for treatment and prevention of ischemic stroke. Coenzyme Q10 is the only lipophilic antioxidant that can be synthesized de novo by cells and plays a key role as an electron carrier in the oxidative phosphorylation of the mitochondrial electron transport chain. However, the reduced form of coenzyme Q10 (Ubiquinol) levels are significantly deficient in the brain. The aim of this article is to review the therapeutic effects and mechanisms of coenzyme Q10 in ischemic stroke.

RECENT FINDINGS

Current studies have found that coenzyme Q10 protects and treats ischemic stroke through multiple mechanisms based on the evidence from in vitro experiments, in vivo experiments, and clinical observations. For the first time, we reviewed the neuroprotective effects of coenzyme Q10 in ischemic stroke. Coenzyme Q10 exerts neuroprotective effects after ischemic stroke through anti-oxidative stress, anti-nitrosative stress, anti-inflammation, and anti-cell death. Here, we provided the evidence on the therapeutic and preventive effects of coenzyme Q10 in ischemic stroke and suggested the potential value of coenzyme Q10 as a medication candidate.

Understanding coenzyme Q

Coenzyme Q (CoQ), also known as ubiquinone, comprises a benzoquinone head group and a long isoprenoid side chain. It is thus extremely hydrophobic and resides in membranes. It is best known for its complex function as an electron transporter in the mitochondrial electron transport chain (ETC) but is also required for several other crucial cellular processes. In fact, CoQ appears to be central to the entire redox balance of the cell. Remarkably, its structure and therefore its properties have not changed from bacteria to vertebrates. In metazoans, it is synthesized in all cells and is found in most, and maybe all, biological membranes. CoQ is also known as a nutritional supplement, mostly because of its involvement with antioxidant defenses. However, whether there is any health benefit from oral consumption of CoQ is not well established. Here we review the function of CoQ as a redox-active molecule in the ETC and other enzymatic systems, its role as a prooxidant in reactive oxygen species generation, and its separate involvement in antioxidant mechanisms. We also review CoQ biosynthesis, which is particularly complex because of its extreme hydrophobicity, as well as the biological consequences of primary and secondary CoQ deficiency, including in human patients. Primary CoQ deficiency is a rare inborn condition due to mutation in CoQ biosynthetic genes. Secondary CoQ deficiency is much more common, as it accompanies a variety of pathological conditions, including mitochondrial disorders as well as aging. In this context, we discuss the importance, but also the great difficulty, of alleviating CoQ deficiency by CoQ supplementation.

Coenzyme Q10 supplementation affects cellular ionic balance: relevance to aging

Aging results into disruptive physiological functioning and cellular processes that affect the composition and structure of the plasma membrane. The plasma membrane is the major regulator of ionic homeostasis that regulates the functioning of membrane transporters and exchangers. Coenzyme Q10 is a lipid-soluble antioxidant molecule that declines during aging and age-associated diseases. The present study aims to explore the role of Coenzyme Q10 supplementation to rats during aging on membrane transporters and redox biomarkers. The study was conducted on young and old male Wistar rats supplemented with 20 mg/kg b.w. of Coenzyme Q10 per day. After a period of 28 days, rats were sacrificed and erythrocyte membrane was isolated. The result exhibits significant decline in biomarkers of oxidative stress in old control rats when compared with young control. The effect of Coenzyme Q10 supplementation was more pronounced in old rats. The functioning of membrane transporters and Na+/H+ exchanger showed potential return to normal levels in the Coenzyme Q10 treated rats. Overall, the results demonstrate that Coenzyme Q10 plays an important role in maintaining redox balance in cells which interconnects with membrane integrity. Thus, Coenzyme Q10 supplementation may play an important role in protecting age related alterations in erythrocyte membrane physiology.

Coenzyme Q10 and Autoimmune Disorders: An Overview

Some 90 autoimmune disorders have been described in medical literature, affecting most of the tissues within the body. Autoimmune disorders may be difficult to treat, and there is a need to develop novel therapeutic strategies for these disorders. Autoimmune disorders are characterised by mitochondrial dysfunction, oxidative stress, and inflammation; there is therefore a rationale for a role for coenzyme Q10 in the management of these disorders, on the basis of its key role in normal mitochondrial function, as an antioxidant, and as an anti-inflammatory agent. In this article, we have therefore reviewed the potential role of CoQ10, in terms of both deficiency and/or supplementation, in a range of autoimmune disorders.

Coenzyme Q biochemistry and biosynthesis

Coenzyme Q (CoQ) is a remarkably hydrophobic, redox-active lipid that empowers diverse cellular processes. Although most known for shuttling electrons between mitochondrial electron transport chain (ETC) complexes, the roles for CoQ are far more wide-reaching and ever-expanding. CoQ serves as a conduit for electrons from myriad pathways to enter the ETC, acts as a cofactor for biosynthetic and catabolic reactions, detoxifies damaging lipid species, and engages in cellular signaling and oxygen sensing. Many open questions remain regarding the biosynthesis, transport, and metabolism of CoQ, which hinders our ability to treat human CoQ deficiency. Here, we recount progress in filling these knowledge gaps, highlight unanswered questions, and underscore the need for novel tools to enable discoveries and improve the treatment of CoQ-related diseases.

Potential Properties of Natural Nutraceuticals and Antioxidants in Age-Related Eye Disorders

Eye health is crucial, and the onset of diseases can reduce vision and affect the quality of life of patients. The main causes of progressive and irreversible vision loss include various pathologies, such as cataracts, ocular atrophy, corneal opacity, age-related macular degeneration, uncorrected refractive error, posterior capsular opacification, uveitis, glaucoma, diabetic retinopathy, retinal detachment, undetermined disease and other disorders involving oxidative stress and inflammation. The eyes are constantly exposed to the external environment and, for this reason, must be protected from damage from the outside. Many drugs, including cortisonics and antinflammatory drugs have widely been used to counteract eye disorders. However, recent advances have been obtained via supplementation with natural antioxidants and nutraceuticals for patients. In particular, evidence has accumulated that polyphenols (mostly deriving from Citrus Bergamia) represent a reliable source of antioxidants able to counteract oxidative stress accompanying early stages of eye diseases. Luteolin in particular has been found to protect photoreceptors, thereby improving vision in many disease states. Moreover, a consistent anti-inflammatory response was found to occur when curcumin is used alone or in combination with other nutraceuticals. Additionally, Coenzyme Q10 has been demonstrated to produce a consistent effect in reducing ocular pressure, thereby leading to protection in patients undergoing glaucoma. Finally, both grape seed extract, rich in anthocyanosides, and polynsatured fatty acids seem to contribute to the prevention of retinal disorders. Thus, a combination of nutraceuticals and antioxidants may represent the right solution for a multi-action activity in eye protection, in association with current drug therapies, and this will be of potential interest in early stages of eye disorders.

Beneficial antioxidant effects of Coenzyme Q10 on reproduction

This chapter focuses on preclinical and clinical studies conducted in recent years that contribute to increasing knowledge on the role of Coenzyme Q10 in female reproductive health. General aspects of CoQ10, such as its role as an antioxidant and in mitochondrial bioenergetics are considered. The age-dependent decline in human female reproductive potential is associated with cellular mitochondrial dysfunction and oxidative stress, and in some cases accompanied by a decrease in CoQ10 levels. Herein, we discuss experimental and clinical evidence on CoQ10 protective effects on reproductive health. We also address the potential of supplementation with this coenzyme to rescue reprotoxicity induced by exposure to environmental xenobiotics. This review not only contributes to our general understanding of the effects of aging on female reproduction but also provides new insights into strategies promoting reproductive health. The use of CoQ10 supplementation can improve reproductive performance through the scavenging of reactive oxygen species and free radicals. This strategy can constitute a low-risk and low-cost strategy to attenuate the impact on fertility related to aging and exposure to environmental chemicals.

Molecular mechanisms underlying the renal protective effects of coenzyme Q10 in acute kidney injury

Coenzyme Q10 (CoQ10), an endogenous antioxidant, has been reported frequently to exert an outstanding protective effect on multiple organ injury, including acute kidney injury (AKI). In this study, we aim to summarize all the current evidence of the protective action of CoQ10 against AKI as there are presently no relevant reviews in the literature. After a systematic search, 20 eligible studies, either clinical trials or experimental studies, were included and further reviewed. CoQ10 treatment exhibited a potent renal protective effect on various types of AKI, such as AKI induced by drugs (e.g., ochratoxin A, cisplatin, gentamicin, L-NAME, and nonsteroidal anti-inflammatory drug), extracorporeal shock wave lithotripsy (ESWL), sepsis, contrast media, and ischemia–reperfusion injury. The renal protective role of CoQ10 against AKI might be mediated by the antiperoxidative, anti-apoptotic, and anti-inflammatory potential of CoQ10. The molecular mechanisms for the protective effects of CoQ10 might be attributed to the regulation of multiple essential genes (e.g., caspase-3, p53, and PON1) and signaling cascades (e.g., Nrf2/HO-1 pathway). This review highlights that CoQ10 may be a potential strategy in the treatment of AKI.

Coenzyme Q10: Role in Less Common Age-Related Disorders

In this article we have reviewed the potential role of coenzyme Q10 (CoQ10) in the pathogenesis and treatment of a number of less common age-related disorders, for many of which effective therapies are not currently available. For most of these disorders, mitochondrial dysfunction, oxidative stress and inflammation have been implicated in the disease process, providing a rationale for the potential therapeutic use of CoQ10, because of its key roles in mitochondrial function, as an antioxidant, and as an anti-inflammatory agent. Disorders reviewed in the article include multi system atrophy, progressive supranuclear palsy, sporadic adult onset ataxia, and pulmonary fibrosis, together with late onset versions of Huntington’s disease, Alexander disease, lupus, anti-phospholipid syndrome, lysosomal storage disorders, fibromyalgia, Machado-Joseph disease, acyl-CoA dehydrogenase deficiency, and Leber’s optic neuropathy.

Secondary Mitochondrial Dysfunction as a Cause of Neurodegenerative Dysfunction in Lysosomal Storage Diseases and an Overview of Potential Therapies

Mitochondrial dysfunction has been recognised a major contributory factor to the pathophysiology of a number of lysosomal storage disorders (LSDs). The cause of mitochondrial dysfunction in LSDs is as yet uncertain, but appears to be triggered by a number of different factors, although oxidative stress and impaired mitophagy appear to be common inhibitory mechanisms shared amongst this group of disorders, including Gaucher’s disease, Niemann–Pick disease, type C, and mucopolysaccharidosis. Many LSDs resulting from defects in lysosomal hydrolase activity show neurodegeneration, which remains challenging to treat. Currently available curative therapies are not sufficient to meet patients’ needs. In view of the documented evidence of mitochondrial dysfunction in the neurodegeneration of LSDs, along with the reciprocal interaction between the mitochondrion and the lysosome, novel therapeutic strategies that target the impairment in both of these organelles could be considered in the clinical management of the long-term neurodegenerative complications of these diseases. The purpose of this review is to outline the putative mechanisms that may be responsible for the reported mitochondrial dysfunction in LSDs and to discuss the new potential therapeutic developments.

Discovering the Potential Value of Coenzyme Q10 in Oxidative Stress: Enlightenment From a Synthesis of Clinical Evidence Based on Various Population

Background: Oxidative stress (OS) is associated with ferroptosis. Coenzyme Q10 (CoQ10), as an adjuvant treatment, has shown to be beneficial against OS. However, the efficacy of CoQ10 as a therapeutic agent against OS has not been promptly updated and systematically investigated.

Methods: A systematic literature search was performed using the Medline, EMBASE, Web of science, Cochrane Central Register of Controlled Trials, CNKI, CBM, Science direct and clinical trial. gov to identify randomized clinical trials evaluating the efficacy of CoQ10 supplementation on OS parameters. Standard mean differences and 95% confidence intervals were calculated for net changes in OS parameters using a random-effects model.

Results: Twenty-one randomized clinical studies met the eligibility criteria to be included in the meta-analysis. Overall, CoQ10 supplementation increased the levels of antioxidant enzymes [including superoxide dismutase (SOD) (SMD = 0.63; 95% CI: 0.38 to 0.88; p < 0.001), catalase (CAT) (SMD = 0.44; 95% CI:0.16 to 0.72; p = 0.002)] significantly and the levels of malondialdehyde (MDA) (SMD = -0.68; 95% CI: 0.93 to -0.43; p < 0.001) was decreased considerably. However, significant associations were not observed between this supplement and total antioxidant capacity (TAC), glutathione peroxidase (GPx) activity.

Conclusion: CoQ10 can improve OS as indicated by statistical significance in CAT and MDA concentrations, as well as SOD activity. Future studies focusing on long-term results and specific valuation of OS parameters are required to confirm the efficacy of CoQ10 on OS. We also believe that with the further research on ferroptosis, CoQ10 will gain more attention.

Systematic Review Registration: [https://inplasy.com/], identifier [INPLASY2021120123].

Lyme Disease: A Role for Coenzyme Q10 Supplementation?

Lyme disease results from a bacterial infection following a bite from an infected tick. Patients are initially treated with antibiotics; however, in cases where antibiotic treatment is delayed, or when patients do not respond to antibiotic treatment, fatigue may develop alongside problems affecting the nervous system, cardiovascular system, and joints. It is thought that most of the damage to these tissues results from the excessive inflammatory response of the host, involving a self-reinforcing cycle of mitochondrial dysfunction, oxidative stress and inflammation. In this article, we review the potential role of supplementary coenzyme Q10 (CoQ10) in mediating the pathogenic mechanism underlying Lyme disease, on the basis of its role in mitochondrial function, as well as its anti-inflammatory and antioxidant actions.

Mechanisms and Therapeutic Effects of Benzoquinone Ring Analogs in Primary CoQ Deficiencies

Coenzyme Q (CoQ) is a conserved polyprenylated lipid composed of a redox-active benzoquinone ring and a long polyisoprenyl tail that serves as a membrane anchor. CoQ biosynthesis involves multiple steps, including multiple modifications of the precursor ring 4-hydroxybenzoic acid. Mutations in the enzymes involved in CoQ biosynthesis pathway result in primary coenzyme Q deficiencies, mitochondrial disorders whose clinical heterogenicity reflects the multiple biological function of CoQ. Patients with these disorders do not always respond to CoQ supplementation, and CoQ analogs have not been successful as alternative approaches. Progress made in understanding the CoQ biosynthesis pathway and studies of supplementation with 4-hydroxybenzoic acid ring analogs have opened a new area in the field of primary CoQ deficiencies treatment. Here, we will review these studies, focusing on efficacy of the different 4-hydroxybenzoic acid ring analogs, models in which they have been tested, and their mechanisms of action. Understanding how these compounds ameliorate biochemical, molecular, and/or clinical phenotypes of CoQ deficiencies is important to develop the most rational treatment for CoQ deficient patients, depending on their molecular defects.

Coenzyme Q10, Ageing and the Nervous System: An Overview

The ageing brain is characterised by changes at the physical, histological, biochemical and physiological levels. This ageing process is associated with an increased risk of developing a number of neurological disorders, notably Alzheimer's disease and Parkinson's disease. There is evidence that mitochondrial dysfunction and oxidative stress play a key role in the pathogenesis of such disorders. In this article, we review the potential therapeutic role in these age-related neurological disorders of supplementary coenzyme Q10, a vitamin-like substance of vital importance for normal mitochondrial function and as an antioxidant. This review is concerned primarily with studies in humans rather than in vitro studies or studies in animal models of neurological disease. In particular, the reasons why the outcomes of clinical trials supplementing coenzyme Q10 in these neurological disorders is discussed.

Coenzyme Q10 and Immune Function: An Overview

Coenzyme Q10 (CoQ10) has a number of important roles in the cell that are required for optimal functioning of the immune system. These include its essential role as an electron carrier in the mitochondrial respiratory chain, enabling the process of oxidative phosphorylation to occur with the concomitant production of ATP, together with its role as a potential lipid-soluble antioxidant, protecting the cell against free radical-induced oxidation. Furthermore, CoQ10 has also been reported to have an anti-inflammatory role via its ability to repress inflammatory gene expression. Recently, CoQ10 has also been reported to play an important function within the lysosome, an organelle central to the immune response. In view of the differing roles CoQ10 plays in the immune system, together with the reported ability of CoQ10 supplementation to improve the functioning of this system, the aim of this article is to review the current literature available on both the role of CoQ10 in human immune function and the effect of CoQ10 supplementation on this system.

Secondary coenzyme Q deficiency in neurological disorders

Coenzyme Q (CoQ) is a ubiquitous lipid serving essential cellular functions. It is the only component of the mitochondrial respiratory chain that can be exogenously absorbed. Here, we provide an overview of current knowledge, controversies, and open questions about CoQ intracellular and tissue distribution, in particular in brain and skeletal muscle. We discuss human neurological diseases and mouse models associated with secondary CoQ deficiency in these tissues and highlight pharmacokinetic and anatomical challenges in exogenous CoQ biodistribution, recent improvements in CoQ formulations and imaging, as well as alternative therapeutical strategies to CoQ supplementation. The last section proposes possible mechanisms underlying secondary CoQ deficiency in human diseases with emphasis on neurological and neuromuscular disorders.

Potential Treatment of Lysosomal Storage Disease through Modulation of the Mitochondrial-Lysosomal Axis

Lysosomal storage disease (LSD) is an inherited metabolic disorder caused by enzyme deficiency in lysosomes. Some treatments for LSD can slow progression, but there are no effective treatments to restore the pathological phenotype to normal levels. Lysosomes and mitochondria interact with each other, and this crosstalk plays a role in the maintenance of cellular homeostasis. Deficiency of lysosome enzymes in LSD impairs the turnover of mitochondrial defects, leading to deterioration of the mitochondrial respiratory chain (MRC). Cells with MRC impairment are associated with reduced lysosomal calcium homeostasis, resulting in impaired autophagic and endolysosomal function. This malicious feedback loop between lysosomes and mitochondria exacerbates LSD. In this review, we assess the interactions between mitochondria and lysosomes and propose the mitochondrial-lysosomal axis as a research target to treat LSD. The importance of the mitochondrial-lysosomal axis has been systematically characterized in several studies, suggesting that proper regulation of this axis represents an important investigative guide for the development of therapeutics for LSD. Therefore, studying the mitochondrial-lysosomal axis will not only add knowledge of the essential physiological processes of LSD, but also provide new strategies for treatment of LSD.

COVID-19, Coenzyme Q10 and Selenium

In COVID-19 infection, a balance must be achieved in immune defence against the virus without precipitating a cytokine storm, which is responsible for lung injury and respiratory distress in severe cases. The initial immune response and the subsequent resolution of inflammation are likely to be dependent on nutritional status, as one contributing factor. Here, we have reviewed the potential link between two specific nutrients, coenzyme Q10 (CoQ10) and selenium, with effects on oxidative stress and inflammation in viral infection. We conclude that both reagents show promise in the treatment of patients with COVID-19 disease. This could give particular relevance over the next several months as promising vaccines are deployed to minimise the COVID-19 spread and as a potential preventative or mitigating approach for future epidemics and pandemics.

Cellular Consequences of Coenzyme Q10 Deficiency in Neurodegeneration of the Retina and Brain

Coenzyme Q10 (CoQ10) is a ubiquitous cofactor in the body, operating in the inner mitochondrial membrane, where it plays a vital role in the generation of adenosine triphosphate (ATP) through the electron transport chain (ETC). In addition to this, CoQ10 serves as an antioxidant, protecting the cell from oxidative stress by reactive oxygen species (ROS) as well as maintaining a proton (H+) gradient across lysosome membranes to facilitate the breakdown of cellular waste products. Through the process of ageing, the body becomes deficient in CoQ10, resulting in several systemic manifestations. On a cellular level, one of the consequences of CoQ10 deficiency is apoptosis, which can be visualised in tissues of the central nervous system (CNS). Diseases affecting the retina and brain such as age-related macular degeneration (AMD), glaucoma, Alzheimer's disease (AD) and Parkinson's disease (PD) have shown defects in cellular biochemical reactions attributed to reduced levels of CoQ10. Through further research into the pathogenesis of such conditions, the effects of CoQ10 deficiency can be counteracted through supplementation, early detection and intervention.

Disorders of Human Coenzyme Q10 Metabolism: An Overview

Coenzyme Q10 (CoQ10) has a number of vital functions in all cells, both mitochondrial and extramitochondrial. In addition to its key role in mitochondrial oxidative phosphorylation, CoQ10 serves as a lipid soluble antioxidant, plays an important role in fatty acid, pyrimidine and lysosomal metabolism, as well as directly mediating the expression of a number of genes, including those involved in inflammation. In view of the central role of CoQ10 in cellular metabolism, it is unsurprising that a CoQ10 deficiency is linked to the pathogenesis of a range of disorders. CoQ10 deficiency is broadly classified into primary or secondary deficiencies. Primary deficiencies result from genetic defects in the multi-step biochemical pathway of CoQ10 synthesis, whereas secondary deficiencies can occur as result of other diseases or certain pharmacotherapies. In this article we have reviewed the clinical consequences of primary and secondary CoQ10 deficiencies, as well as providing some examples of the successful use of CoQ10 supplementation in the treatment of disease.

Mechanisms of Mitochondrial Dysfunction in Lysosomal Storage Disorders: A Review

Mitochondrial dysfunction is emerging as an important contributory factor to the pathophysiology of lysosomal storage disorders (LSDs). The cause of mitochondrial dysfunction in LSDs appears to be multifactorial, although impaired mitophagy and oxidative stress appear to be common inhibitory mechanisms shared amongst these heterogeneous disorders. Once impaired, dysfunctional mitochondria may impact upon the function of the lysosome by the generation of reactive oxygen species as well as depriving the lysosome of ATP which is required by the V-ATPase proton pump to maintain the acidity of the lumen. Given the reported evidence of mitochondrial dysfunction in LSDs together with the important symbiotic relationship between these two organelles, therapeutic strategies targeting both lysosome and mitochondrial dysfunction may be an important consideration in the treatment of LSDs. In this review we examine the putative mechanisms that may be responsible for mitochondrial dysfunction in reported LSDs which will be supplemented with morphological and clinical information.