Mitochondrial Dysfunction and Redox Homeostasis Impairment as Pathomechanisms of Brain Damage in Ethylmalonic Encephalopathy: Insights from Animal and Human Studies

Cellular and Molecular Neurobiology - Ethylmalonic encephalopathy (EE) is a severe intoxication disorder caused by mutations in the ETHE1 gene that encodes a mitochondrial sulfur dioxygenase...     

Maternal Hypermethioninemia Affects Neurons Number,Neurotrophins Levels,Energy Metabolism,and Na<Superscript>+</Superscript>,K<Superscript>+</Superscript>-ATPase Expression/Content in Brain of Rat Offspring

In the current study, we verified the effects of maternal hypermethioninemia on the number of neurons, apoptosis, nerve growth factor, and brain-derived neurotrophic factor levels, energy metabolism parameters (succinate dehydrogenase, complex II, and cytochrome c oxidase), expression and immunocontent of Na⁺,K⁺-ATPase, edema formation, inflammatory markers (tumor necrosis factor-alpha and interleukin-6), and mitochondrial hydrogen peroxide levels in the encephalon from the offspring. Pregnant Wistar rats were divided into two groups: the first one received saline (control) and the second group received 2.68 μmol methionine/g body weight by subcutaneous injections twice a day during gestation (approximately 21 days). After parturition, pups were killed at the 21st day of life for removal of encephalon. Neuronal staining (anti-NeuN) revealed a reduction in number of neurons, which was associated to decreased nerve growth factor and brain-derived neurotrophic factor levels. Maternal hypermethioninemia also reduced succinate dehydrogenase and complex II activities and increased expression and immunocontent of Na⁺,K⁺-ATPase alpha subunits. These results indicate that maternal hypermethioninemia may be a predisposing factor for damage to the brain during the intrauterine life.     

3-Hydroxy-3-methylglutaric and 3-methylglutaric acids impair redox status and energy production and transfer in rat heart: relevance for the pathophysiology of cardiac dysfunction in 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency

3-Hydroxy-3-methylglutaryl-coenzyme A lyase (HL) deficiency is characterized by tissue accumulation of 3-hydroxy-3-methylglutaric (HMG), and 3-methylglutaric (MGA) acids. Affected patients present cardiomyopathy, whose pathomechanisms are not yet established. We investigated the effects of HMG and MGA on energy and redox homeostasis in rat heart using in vivo and in vitro models. In vivo experiments showed that intraperitoneal administration of HMG and MGA decreased the activities of the respiratory chain complex II and creatine kinase (CK), whereas HMG also decreased the activity of complex II–III. Furthermore, HMG and MGA injection increased reactive species production and carbonyl formation, and decreased glutathione concentrations. Regarding the enzymatic antioxidant defenses, HMG and MGA increased glutathione peroxidase (GPx) and glutathione reductase (GR) activities, while only MGA diminished the activities of superoxide dismutase (SOD) and catalase, as well as the protein content of SOD1. Pre-treatment with melatonin (MEL) prevented MGA-induced decrease of CK activity and SOD1 levels. In vitro results demonstrated that HMG and MGA increased reactive species formation, induced lipid peroxidation and decreased glutathione. We also verified that reactive species overproduction and glutathione decrease provoked by HMG and MGA were abrogated by MEL and lipoic acid (LA), while only MEL prevented HMG- and MGA-induced lipoperoxidation. Allopurinol (ALP) also prevented reactive species overproduction caused by both metabolites. Our data provide solid evidence that bioenergetics dysfunction and oxidative stress are induced by HMG and MGA in heart, which may explain the cardiac dysfunction observed in HL deficiency, and also suggest that antioxidant supplementation could be considered as adjuvant therapy for affected patients.     

Antioxidant properties of mesenchymal stem cells against oxidative stress in a murine model of colitis

Objective

To investigate the effects of oxidative stress injury in dextran sulfate sodium (DSS)-induced colitis in mice treated with mesenchymal stem cells (MSC).

Results

Mice exposed to oral administration of 2% DSS over 7 days presented a high disease activity index and an intense colonic inflammation. Systemic infusion of MSC protected from severe colitis, reducing weight loss and diarrhea while lowering the infiltration of inflammatory cells. Moreover, toxic colitis injury increased oxidative stress. Administration of DSS decreased reduced glutathione (GSH) and superoxide dismutase (SOD) activity, and increased thiobarbituric acid-reactive substances levels in the colon. No alteration was found in catalase (CAT) and glutathione peroxidase (GPx) activity. Otherwise, MSC transplantation was able to prevent the decrease of GSH levels and SOD activity suggestive of an antioxidant property of MSC.

Conclusion

The oxidative stress is a pathomechanism underlying the pathophysiology of colitis and MSC play an important role in preventing the impairment of antioxidants defenses in inflamed colon.

     

Creatine nanoliposome reverts the HPA-induced damage in complex II–III activity of the rats’ cerebral cortex

Molecular Biology Reports - Phenylketonuria (PKU) is a metabolic disorder accumulating phenylalanine (Phe) and its metabolites in plasma and tissues of the patients. Regardless of the mechanisms,...     

Long-chain 3-hydroxy fatty acids accumulating in long-chain 3-hydroxyacyl-CoA dehydrogenase and mitochondrial trifunctional protein deficiencies uncouple oxidative phosphorylation in heart mitochondria

Cardiomyopathy is a common clinical feature of some inherited disorders of mitochondrial fatty acid β-oxidation including mitochondrial trifunctional protein (MTP) and isolated long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiencies. Since individuals affected by these disorders present tissue accumulation of various fatty acids, including long-chain 3-hydroxy fatty acids, in the present study we investigated the effect of 3-hydroxydecanoic (3 HDCA), 3-hydroxydodecanoic (3 HDDA), 3-hydroxytetradecanoic (3 HTA) and 3-hydroxypalmitic (3 HPA) acids on mitochondrial oxidative metabolism, estimated by oximetry, NAD(P)H content, hydrogen peroxide production, membrane potential (ΔΨ) and swelling in rat heart mitochondrial preparations. We observed that 3 HTA and 3 HPA increased resting respiration and diminished the respiratory control and ADP/O ratios using glutamate/malate or succinate as substrates. Furthermore, 3 HDDA, 3 HTA and 3 HPA decreased ΔΨ, the matrix NAD(P)H pool and hydrogen peroxide production. These data indicate that these fatty acids behave as uncouplers of oxidative phosphorylation. We also verified that 3 HTA-induced uncoupling-effect was not mediated by the adenine nucleotide translocator and that this fatty acid induced the mitochondrial permeability transition pore opening in calcium-loaded organelles since cyclosporin A prevented the reduction of mitochondrial ΔΨ and swelling provoked by 3 HTA. The present data indicate that major 3-hydroxylated fatty acids accumulating in MTP and LCHAD deficiencies behave as strong uncouplers of oxidative phosphorylation potentially impairing heart energy homeostasis.     

Neurochemical Evidence that the Metabolites Accumulating in 3-Methylcrotonyl-CoA Carboxylase Deficiency Induce Oxidative Damage in Cerebral Cortex of Young Rats

Isolated 3-methylcrotonyl-CoA carboxylase deficiency (3MCCD) is an autosomal recessive disorder of leucine metabolism biochemically characterized by accumulation of 3-methylcrotonylglycine (3MCG), 3-methylcrotonic acid (3MCA) and 3-hydroxyisovaleric acid. A considerable number of affected individuals present neurological symptoms with or without precedent crises of metabolic decompensation and brain abnormalities whose pathogenesis is poorly known. We investigated the in vitro effects of 3MCG and 3MCA on important parameters of oxidative stress in cerebral cortex of young rats. 3MCG and 3MCA significantly increased TBA-RS and carbonyl formation, indicating that these compounds provoke lipid and protein oxidation, respectively. In contrast, nitric oxide production was not affected by 3MCG and 3MCA. Furthermore, 3MCG- and 3MCA-induced elevation of TBA-RS values was fully prevented by melatonin, trolox and reduced glutathione, but not by the nitric oxide inhibitor N^??-nitro-l-arginine methyl ester or the combination of catalase plus superoxide dismutase, indicating that reactive oxygen species were involved in the oxidative damage caused by these compounds. We also found that the activity of the antioxidant enzymes glutathione peroxidase, catalase, superoxide dismutase and glutathione reductase were not altered in vitro by 3MCG and 3MCA. It is therefore presumed that alterations of the cellular redox homeostasis caused by the major metabolites accumulating in 3MCCD may potentially be involved in the pathophysiology of the neurological dysfunction and structural brain alterations found in patients affected by this disorder.     

Promotion of Lipid and Protein Oxidative Damage in Rat Brain by Ethylmalonic Acid

High concentrations of ethylmalonic acid are found in tissues and biological fluids of patients affected by ethylmalonic encephalopathy, deficiency of short-chain acyl-CoA dehydrogenase activity and other illnesses characterized by developmental delay and neuromuscular symptoms. The pathophysiological mechanisms responsible for the brain damage in these patients are virtually unknown. Therefore, in the present work we investigated the in vitro effect of EMA on oxidative stress parameters in rat cerebral cortex. EMA significantly increased chemiluminescence and thiobarbituric acid-reactive species levels (lipoperoxidation), as well as carbonyl content and oxidation of sulfhydryl groups (protein oxidative damage) and DCFH. EMA also significantly decreased the levels of reduced glutathione (non-enzymatic antioxidant defenses). In contrast, nitrate and nitrite levels were not affected by this short organic acid. It is therefore presumed that oxidative stress may represent a pathomechanism involved in the pathophysiology of the neurologic symptoms manifested by patients affected by disorders in which EMA accumulates.