title: Vulnerability to oxidative stress in vitro in pathophysiology of mitochondrial short-chain acyl-CoA dehydrogenase deficiency: response to antioxidants.
abstract: OBJECTIVE
  To elucidate the pathophysiology of SCAD deficient patients who have a unique neurological phenotype, among fatty acid oxidation disorders, with early developmental delay, CNS malformations, intractable seizures, myopathy and clinical signs suggesting oxidative stress.
  
  
  METHODS
  We studied skin fibroblast cultures from patients homozygous for ACADS common variant c.625G>A (n = 10), compound heterozygous for c.625G>A/c.319C>T (n = 3) or homozygous for pathogenic c.319C>T (n = 2) and c.1138C>T (n = 2) mutations compared to fibroblasts from patients with carnitine palmitoyltransferase 2 (CPT2) (n = 5), mitochondrial trifunctional protein (MTP)/long-chain L-3-hydroxyacyl-CoA dehydrogenase (LCHAD) (n = 7), and medium-chain acyl-CoA dehydrogenase (MCAD) deficiencies (n = 4) and normal controls (n = 9). All were exposed to 50 µM menadione at 37°C. Additional conditions included exposure to 39°C and/or hypoglycemia. Time to 100% cell death was confirmed with trypan blue dye exclusion. Experiments were repeated with antioxidants (Vitamins C and E or N-acetylcysteine), Bezafibrate or glucose and temperature rescue.
  
  
  RESULTS
  The most significant risk factor for vulnerability to menadione-induced oxidative stress was the presence of a FAO defect. SCADD fibroblasts were the most vulnerable compared to other FAO disorders and controls, and were similarly affected, independent of genotype. Cell death was exacerbated by hyperthermia and/or hypoglycemia. Hyperthermia was a more significant independent risk factor than hypoglycemia. Rescue significantly prolonged survival. Incubation with antioxidants and Bezafibrate significantly increased viability of SCADD fibroblasts.
  
  
  CONCLUSIONS
  Vulnerability to oxidative stress likely contributes to neurotoxicity of SCADD regardless of ACADS genotype and is significantly exacerbated by hyperthermia. We recommend rigorous temperature control in SCADD patients during acute illness. Antioxidants and Bezafibrate may also prove instrumental in their management.
authors.affiliation: Neurometabolic Research Laboratory, Division of Neurology, Department of Pediatrics, Hospital for Sick Children, Toronto, Canada.
authors.forename: Zarazuela
authors.initials: Z
authors.lastname: Zolkipli
authors.forename: Christina B
authors.initials: CB
authors.lastname: Pedersen
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Lamhonwah
authors.forename: Niels
authors.initials: N
authors.lastname: Gregersen
authors.forename: Ingrid
authors.initials: I
authors.lastname: Tein
mesh_terms: D042964:Acyl-CoA Dehydrogenase / Q000172:deficiency / Q000378:metabolism; D000293:Adolescent; D000975:Antioxidants / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008052:Lipid Metabolism, Inborn Errors / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D024483:Vitamin K 3 / Q000633:toxicity
chemical_list: D000975:Antioxidants; D024483:Vitamin K 3; D042964:Acyl-CoA Dehydrogenase