Coenzyme Q10and its Relation with Oxidant and Antioxidant System Markers in Patients with End-Stage Renal Disease

Oxidative Stress in Hemodialysis Patients: Pathophysiological Mechanisms, Clinical Consequences and Basic Principles of Treatment

Cardiovascular diseases are the leading cause of death in patients who undergo regular hemodialysis. Oxidative stress is a non-traditional risk factor for the development of cardiovascular diseases in this population of patients. It is defined as tissue damage caused by balance disturbance between the formation of free radicals and the function of protective antioxidative systems. The superoxide anion and hydrogen peroxide are precursors in the formation of stronger oxidants, such as: hydroxyl radical, peroxynitrite and hypochloric acid. Superoxide dismutase is the first line of antioxidant protection while catalase, glutathione peroxidase, trace elements, vitamin C, vitamin E, N-acetylcysteine and coenzyme Q10 also have a significant antioxidative role. Hemo-dialysis is itself a trigger for the increased formation of oxygen free radicals. The two main pathophysiological mechanisms of the increased formation of free oxygen radicals during the hemo-dialysis session are: bionicompatibility of the dialysis membrane and the presence of endotoxins in the hemodialysis solution. The measurement of myeloperoxidase concentration in a patient’s serum during hemodialysis is an indicator of the severity of oxidative stress induced by the dialysis membrane (an indicator of the biocompatibility of the dialysis membrane). The main clinical consequences of oxidative stress include: atherosclerosis, erythropoietin resistance, malnutrition and amyloidosis associated with hemodialysis. The evaluation of oxidative stress in patients undergoing hemodialysis is performed by measuring the concentration of lipid peroxidation products (malonyldialdehyde, 4-hydroxynonenal, TBARS, F2-isoprostane, oxLDL), protein oxidation (AOPP), protein gelling (AGE), and oxidation of nucleic acids (8-OHdG). The antioxidant treatment strategy consists of replenishing vitamin C, vitamin E, selenium, N-acetylcysteine and coenzyme Q10. On-line hemodialysis, a biocompatible vitamin E-coated dialysis membrane, an ultra-pure solution for hemodialysis, prevent oxidative stress, reduce the rate of cardiovascular morbidity and mortality and improve life quality of patients treated with regular hemodialysis.

Clinical Trial of the Effects of Coenzyme Q10 Supplementation on Biomarkers of Inflammation and Oxidative Stress in Diabetic Hemodialysis Patients

Background

The aim of the study was to determine the effects of coenzyme Q10 (CoQ10) supplementation on biomarkers of inflammation and oxidative stress among diabetic hemodialysis (HD) patients.

Methods

Sixty diabetic HD patients participated in the randomized, double blind, placebo-controlled clinical trial. They were randomly assigned into two groups to intake either 60 mg CoQ10 supplements (n = 30) or placebo (n = 30) twice a day for 12 weeks.

Results

After 12 weeks of intervention, CoQ10 supplementation significantly increased total antioxidant (TAC) (54.921 ± 26.437 vs. -126.781 ± 26.437, P < 0.001) and nitric oxide (NO) levels (4.121 ± 1.314 vs. -1.427 ± 1.314, P = 0.006) and decreased C-reactive protein (CRP) (-1.302 ± 0.583 vs. 0.345 ± 0.583, 0.042) levels compared with the placebo. We did not observe any significant effect of CoQ10 supplementation on malondialdehyde (MDA) and glutathione (GSH) levels compared with the placebo.

Conclusions

Overall, our study showed that CoQ10 supplementation to diabetic HD patients for 12 weeks was associated with increased levels of TAC and NO levels and decreased level of high-sensitivity CRP (hs-CRP) levels, but did not have any beneficial effects on MDA and GSH.

Role of the Soluble Receptor for Advanced Glycation End Products (sRAGE) as a Prognostic Factor for Mortality in Hemodialysis and Peritoneal Dialysis Patients

End-stage renal disease patients on dialysis (CKD-G5D) have a high mortality rate due to cardiovascular diseases (CVD). In these patients, inflammation, oxidative stress, and uremia increase the production of glycation products (AGEs) which in turn accelerate CVD onset and progression. Recently, attention has been given to the soluble receptor for AGEs (sRAGE) as a marker of inflammation, oxidative stress, atherosclerosis, and heart failure in CKD-G5D. However, its association with patient outcomes is still under debate. Our aim is to explore whether sRAGE may be a predictor of mortality in CKD-G5D. We studied 123 CKD-G5D for 24 months. Of these patients, 56 were on hemodialysis (HD) and 67 on peritoneal dialysis (PD). Demographic, anthropometric, biochemical, and clinical data were recorded. sRAGE was quantified by enzyme-linked immunosorbent assay. sRAGE was a predictor of mortality at 2-year follow-up. Each increase of 100 pg/mL in sRAGE levels was associated with an approximately 7% increased risk of mortality. Furthermore, in the entire study group, as well as in PD and HD patient subgroups, sRAGE was positively correlated with brain natriuretic peptide (BNP) levels. Mortality rates as well as sRAGE levels in patients who died did not differ between PD and HD patients. In conclusion, the positive association observed with BNP levels suggests a role for sRAGE as a prognostic factor for mortality in CKD-G5D patients displaying an active process of cardiac remodeling.

Effects of Coenzyme Q10 Supplementation on Exercise Performance and Markers of Oxidative Stress in Hemodialysis Patients: A Double-Blind Placebo-Controlled Crossover Trial

Coenzyme Q10 (CoQ10) supplementation has been shown to decrease oxidative stress in a number of clinical settings. However, there are mixed results regarding the role of CoQ10 supplementation on exercise performance. Chronic kidney disease is recognized as an inflammatory state, and hemodialysis patients have low level of exercise performance. We aimed to evaluate the effect of CoQ10 supplementation on oxidative stress markers and exercise performance measures. This was a prospective, double-blind, placebo-controlled, crossover study in which all patients received placebo and oral CoQ10 200 mg/d. Participants underwent 6-minute walking test and cycle ergometer. Blood samples were drawn to determine malondialdehyde, oxidized low-density lipoprotein, superoxide dismutase, and glutathione peroxidase. Walking distance in 6-minute walking test and estimated maximal oxygen consumption (VO2max) were recorded. Twenty-eight patients were randomized, but 23 patients completed the study protocol. Serum CoQ10 level significantly increased with supplementation compared with basal values (P < 0.05). Neither walking distance nor estimated VO2max was different between the placebo and CoQ10 groups (P > 0.05). Serum malondialdehyde levels significantly increased in both groups compared with baseline values just after the exercise (P < 0.05). There was no difference in markers of oxidative stress and antioxidant system between placebo and CoQ10 supplementation with exercise (P > 0.05). The results of this study showed no significant effect of CoQ10 supplementation on exercise performance measures and oxidative system markers compared with placebo in maintenance hemodialysis patients.

Effects of coenzyme Q10 supplementation on C-reactive protein and homocysteine as the inflammatory markers in hemodialysis patients; a randomized clinical trial

Background: The most leading cause of death in end-stage renal disease (ESRD) patients are cardiovascular disease and inflammatory markers are related to coronary events. CO-Q10 (coenzyme Q10) is a protective supplement from free radical oxidative damage. In addition, hyperhomocysteinemia is an independent coronary artery disease (CAD) risk factor.

Objectives: Due to increasing oxidative stress in dialysis patients, and the effect of CO-Q10 in decrease oxidative stress, in this work, we assessed the effect of CO-Q10 on C-reactive protein (CRP) level as an inflammatory marker and homocysteine in dialysis patients.

Patients and Methods: This was a single-blind, randomized cross over clinical trial. Patients with ESRD were randomly allotted to two groups. All patients received placebo and C0- Q10 100mg/d during the three months in each stage, with two week washout period. Plasma level of CRP and homocysteine from the start of the work and at the conclusion of each menses, are evaluated.

Results: Thirty-four patients randomized, but 26 patients complete study protocol. The treatment effect of CO-Q10 on CRP level is significant (P < 0.001) (95% CI = -20.1 to -10.5) and it was also significant for the increasing albumin level. (P = 0.044) (95% CI = 0. 0-0.6), But there was not any substantial effect on serum homocysteine level (P = 0.630).

Conclusions: CO-Q10 could significantly decrease CRP level as an inflammatory marker and can protect cardiovascular events.

A review on the role of quinones in renal disorders

Quinones are electron and proton carriers that play a primary role in the aerobic metabolism of virtually every cell in nature. Most physiological quinones are benzoquinones. They undergo highly regulated redox reactions in the mitochondria, Golgi apparatus, plasma membrane and endoplasmic reticulum. Important consequences of these electron transfer reactions are the production of and protection against reactive oxygen species (ROS). Quinones have been extensively studied for both their cytotoxic as well as cellular protective properties and they have been particularly useful in rational drug design. The role of quinones in medicine is explored in this literature review with a particular focus on renal diseases. Due to their high basal metabolism and detoxification role, the kidneys are particularly sensitive to oxidative stress. Regardless of the underlying etiology, ROS plays an important role in both acute kidney injury (AKI) and chronic kidney diseases (CKD). Depending on the oxidative state of the kidney, quinones can be nephrotoxoic or nephro-protective. Many factors play a role in the interaction between quinones and the kidney and the consequences of this are just beginning to be explored.

Serum coenzyme Q10 levels are associated with coronary flow reserve in hemodialysis patients

Accelerated atherosclerosis is the major cause of mortality in patients on chronic hemodialysis (HD). The aim of this study was to evaluate the relation between coenzyme Q10 (CoQ10) levels and coronary flow reserve (CFR) in HD patients as an indicator of atherosclerosis. Seventy-one chronic HD patients and 65 age- and sex-matched healthy individuals were included in the study. Plasma CoQ10 levels were performed by high-performance liquid chromatography measurements. CFR was assessed by transthoracic Doppler echocardiography. Serum CoQ10 levels (1.36 ± 0.43 vs. 2.53 ± 0.55, P < 0.001) and CFR values (1.73 ± 0.11 vs. 2.32 ± 0.28, P < 0.001) were significantly lower in HD patients compared with controls. There was a significant positive correlation between CFR and serum levels of CoQ10 (r = 0.669, P < 0.001). A linear regression analysis showed that serum levels of CoQ10 were still significantly and positively correlated with CFR (regression coefficient = 0.235, P < 0.001). Our data have demonstrated that HD patients exhibit decreased plasma CoQ10 levels and CFR values. The study also showed for the first time that serum CoQ10 levels independently predict CFR in HD patients.