Higher Vulnerability of Menadione-Exposed Cortical Astrocytes of Glutaryl-CoA Dehydrogenase Deficient Mice to Oxidative Stress, Mitochondrial Dysfunction, and Cell Death: Implications for the Neurodegeneration in Glutaric Aciduria Type I

Abstract

Patients affected by glutaric aciduria type I (GA-I) show progressive cortical leukoencephalopathy whose pathogenesis is poorly known. In the present work, we exposed cortical astrocytes of wild-type (Gcdh ) and glutaryl-CoA dehydrogenase knockout (Gcdh ) mice to the oxidative stress inducer menadione and measured mitochondrial bioenergetics, redox homeostasis, and cell viability. Mitochondrial function (MTT and JC1-mitochondrial membrane potential assays), redox homeostasis (DCFH oxidation, nitrate and nitrite production, GSH concentrations and activities of the antioxidant enzymes SOD and GPx), and cell death (propidium iodide incorporation) were evaluated in primary cortical astrocyte cultures of Gcdh and Gcdh mice unstimulated and stimulated by menadione. We also measured the pro-inflammatory response (TNFα levels, IL1-β and NF-ƙB) in unstimulated astrocytes obtained from these mice. Gcdh mice astrocytes were more vulnerable to menadione-induced oxidative stress (decreased GSH concentrations and altered activities of the antioxidant enzymes), mitochondrial dysfunction (decrease of MTT reduction and JC1 values), and cell death as compared with Gcdh astrocytes. A higher inflammatory response (TNFα, IL1-β and NF-ƙB) was also observed in Gcdh mice astrocytes. These data indicate a higher susceptibility of Gcdh cortical astrocytes to oxidative stress and mitochondrial dysfunction, probably leading to cell death. It is presumed that these pathomechanisms may contribute to the cortical leukodystrophy observed in GA-I patients.

Oxidative damage in glutaric aciduria type I patients and the protective effects of l‐carnitine treatment

“…Our human findings agree with the animal data showing inflammation and oxidative stress in the genetic mouse GA‐I model . In this context, it is emphasized that increased pro‐inflammatory cytokines can be related to an excessive production of reactive species, contributing to inflammation .…”

“…This may be possibly explained by the fact that L-car has antinitrative properties, preventing nitration of protein tyrosine residues caused by peroxynitrite. 43,44 In this context, it is emphasized that increased pro-inflammatory cytokines can be related to an excessive production of reactive species, contributing to inflammation. 42 We also observed that GA-I patients presented an increase of the pro-inflammatory cytokines IL-6, IL-8, GM-CSF, and TNF-α in plasma, in relation to the control group, indicating a pro-inflammatory state in these patients, that has not been so far evaluated in GA-I patients.…”

“…4 Our human findings agree with the animal data showing inflammation and oxidative stress in the genetic mouse GA-I model. 43,44 In this context, it is emphasized that increased pro-inflammatory cytokines can be related to an excessive production of reactive species, contributing to inflammation. 45 Furthermore, the NFκB can be activated by TNF-α, resulting in increased NO and H 2 O 2 production in the cells and, consequently, RNS, mainly peroxynitrite, which, in turn, can lead to a nitrosative stress and damage to the biomolecules.…”

Elevated levels of BDNF and cathepsin‐das possible peripheral markers of neurodegeneration in plasma of patients with glutaric acidemia type I

“…It should be also noted that GA1 patients present high levels of proinflammatory cytokines (Guerreiro et al, 2018), as well as marked elevation of various parameters of oxidative stress in plasma and urine (Guerreiro et al, 2015;Mescka et al, 2013). In line with these findings, disturbance of redox homeostasis, glutamatergic neurotransmission, vascular alterations, and inflammatory processes were also observed in cortex and striatum of the GA1 knockout animal model (Amaral et al, 2015;Rodrigues et al, 2016;Wajner et al, 2019). It was also demonstrated that disturbance of redox homeostasis were associated with inflammatory processes induced by quinolinic acid administration in striatum of these mice subjected to dietary lysine overload (Seminotti et al, , 2014.…”

Protective effects of grape seed procyanidin on isoflurane-induced cognitive impairment in mice

“…If cellular antioxidants fail to scavenge ROS, oxidative damage ensues, leading to cytotoxicity and resulting in protein collapse, enzyme failure and lipid destruction (Lee et al 2012). Furthermore, this could result in the destruction of the neuronal tissue, causing cognitive impairment (Kojima et al 2013;Rodrigues et al 2017).…”