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The Effect of Methylmalonic Acid Treatment on Human Neuronal Cell Coenzyme Q₁₀ Status and Mitochondrial Function.

ABSTRACT: Methylmalonic acidemia is an inborn metabolic disease of propionate catabolism, biochemically characterized by accumulation of methylmalonic acid (MMA) to millimolar concentrations in tissues and body fluids. However, MMA's role in the pathophysiology of the disorder and its status as a "toxic intermediate" is unclear, despite evidence for its ability to compromise antioxidant defenses and induce mitochondrial dysfunction. Coenzyme Q₁₀ (CoQ₁₀) is a prominent electron carrier in the mitochondrial respiratory chain (MRC) and a lipid-soluble antioxidant which has been reported to be deficient in patient-derived fibroblasts and renal tissue from an animal model of the disease. However, at present, it is uncertain which factors are responsible for inducing this CoQ₁₀ deficiency or the effect of this deficit in CoQ₁₀ status on mitochondrial function. Therefore, in this study, we investigated the potential of MMA, the principal metabolite that accumulates in methylmalonic acidemia, to induce a cellular CoQ₁₀ deficiency. In view of the severe neurological presentation of patients with this condition, human neuroblastoma SH-SY5Y cells were used as a neuronal cell model for this investigation. Following treatment with pathological concentrations of MMA (>0.5 mM), we found a significant (p = 0.0087) ~75% reduction in neuronal cell CoQ₁₀ status together with a significant (p = 0.0099) decrease in MRC complex II-III activity at higher concentrations (>2 mM). The deficits in neuronal CoQ₁₀ status and MRC complex II-III activity were associated with a loss of cell viability. However, no significant impairment of mitochondrial membrane potential (??m) was detectable. These findings indicate the potential of pathological concentrations of MMA to induce a neuronal cell CoQ₁₀ deficiency with an associated loss of MRC complex II-III activity. However, in the absence of an impairment of ??m, the contribution this potential deficit in cellular CoQ₁₀ status makes towards the disease pathophysiology methylmalonic acidemia has yet to be fully elucidated.

SUBMITTER: Proctor EC

PROVIDER: S-EPMC7730949 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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The Effect of Methylmalonic Acid Treatment on Human Neuronal Cell Coenzyme Q10 Status and Mitochondrial Function.

Proctor Emma C EC Turton Nadia N Boan Elle Jo EJ Bennett Emily E Philips Suzannah S Heaton Robert A RA Hargreaves Iain P IP

International journal of molecular sciences 20201130 23

Methylmalonic acidemia is an inborn metabolic disease of propionate catabolism, biochemically characterized by accumulation of methylmalonic acid (MMA) to millimolar concentrations in tissues and body fluids. However, MMA's role in the pathophysiology of the disorder and its status as a "toxic intermediate" is unclear, despite evidence for its ability to compromise antioxidant defenses and induce mitochondrial dysfunction. Coenzyme Q10 (CoQ10) is a prominent electron carrie ...[more]

PMID: 33266298

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Project description:BackgroundOxidative stress is highly prevalent in patients with end-stage renal disease and is linked to excess cardiovascular risk. Identifying therapies that reduce oxidative stress has the potential to improve cardiovascular outcomes in patients undergoing maintenance dialysis.Study designPlacebo-controlled, 3-arm, double-blind, randomized, clinical trial.Setting & participants65 patients undergoing thrice-weekly maintenance hemodialysis.InterventionPatients were randomly assigned in a 1:1:1 ratio to receive once-daily coenzyme Q10 (CoQ10; 600 or 1,200mg) or matching placebo for 4 months.OutcomesThe primary outcome was plasma oxidative stress, defined as plasma concentration of F2-isoprotanes. Secondary outcomes included levels of plasma isofurans, levels of cardiac biomarkers, predialysis blood pressure, and safety/tolerability.MeasurementsF2-isoprostanes and isofurans were measured as plasma markers of oxidative stress, and N-terminal pro-brain natriuretic peptide and troponin T were measured as cardiac biomarkers at baseline and 1, 2, and 4 months.ResultsOf 80 randomly assigned patients, 15 were excluded due to not completing at least 1 postbaseline study visit and 65 were included in the primary intention-to-treat analysis. No treatment-related major adverse events occurred. Daily treatment with 1,200mg, but not 600mg, of CoQ10 significantly reduced plasma F2-isoprostanes concentrations at 4 months compared to placebo (adjusted mean changes of -10.7 [95% CI, -7.1 to -14.3] pg/mL [P<0.001] and -8.3 [95% CI, -5.5 to -11.0] pg/mL [P=0.1], respectively). There were no significant effects of CoQ10 treatment on levels of plasma isofurans, cardiac biomarkers, or predialysis blood pressures.LimitationsStudy not powered to detect small treatment effects; difference in baseline characteristics among randomized groups.ConclusionsIn patients undergoing maintenance hemodialysis, daily supplementation with 1,200mg of CoQ10 is safe and results in a reduction in plasma concentrations of F2-isoprostanes, a marker of oxidative stress. Future studies are needed to determine whether CoQ10 supplementation improves clinical outcomes for patients undergoing maintenance hemodialysis.

Project description:Statins are efficient cholesterol-lowering medicines utilized worldwide. However, 10% of patients suffer from adverse effects specially related to skeletal muscle function. Pro- or anti-oxidant effects of statins have been reported. Here we hypothesized that statins induce muscle mitochondrial oxidative stress leading to mitochondrial permeability transition (MPT) which may explain statin muscle toxicity. Thus, our aims were to investigate the effects of statin chronic treatment on muscle mitochondrial respiration rates, MPT and redox state indicators in the context of hypercholesterolemia. For this purpose, we studied muscle biopsies of the hypercholesterolemic LDL receptor knockout mice (LDLr-/-) treated with pravastatin during 3 months. Plantaris, but not soleus muscle of treated mice showed significant inhibition of respiration rates induced by ADP (-14%), oligomycin (-20%) or FCCP (-40%). Inhibitions of respiratory rates were sensitive to EGTA (Ca2+ chelator), cyclosporin A (MPT inhibitor), ruthenium red (inhibitor of mitochondria Ca2+ uptake) and coenzyme Q10 (antioxidant), indicating that pravastatin treatment favors Ca2+ induced MPT. Diet supplementation with creatine (antioxidant) also protected treated mice against pravastatin sensitization to Ca2+ induced MPT. Among several antioxidant enzymes analyzed, only catalase activity was increased by 30% in plantaris muscle of pravastatin treated mice. Oxidized lipids, but not proteins biomarkers were identified in treated LDLr-/- plantaris muscle. Taken together, the present results suggest that chronic pravastatin administration to a model of familial hypercholesterolemia promotes mitochondrial dysfunctions in plantaris muscle that can be counteracted by antioxidants administered either in vitro (CoQ10) or in vivo (creatine). Therefore, we propose that inhibition of muscle mitochondrial respiration by pravastatin leads to an oxidative stress that, in the presence of calcium, opens the permeability transition pore. This mitochondrial oxidative stress caused by statin treatment also signals for cellular antioxidant system responses such as catalase upregulation. These results suggest that the detrimental effects of statins on muscle mitochondria could be prevented by co-administration of a safe antioxidant such as creatine or CoQ10.

Dataset Information

The Effect of Methylmalonic Acid Treatment on Human Neuronal Cell Coenzyme Q₁₀ Status and Mitochondrial Function.

Publications

The Effect of Methylmalonic Acid Treatment on Human Neuronal Cell Coenzyme Q<sub>10</sub> Status and Mitochondrial Function.

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