Lipid peroxidation biomarkers for evaluating oxidative stress in equine neuroaxonal dystrophy

BackgroundHypothesisEquine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disorder affecting genetically predisposed foals maintained on an -tocopherol (-TOH) deficient diet. Currently no antemortem diagnostic test for eNAD/EDM is available. Because -TOH deficiency is associated with increased lipid peroxidation, it was hypothesized that F-2-isoprostanes (F(2)IsoP), F-4-neuroprostanes (F4NP) and oxysterols derived from free radical oxidation would be increased in the cerebrospinal fluid (CSF) and neural tissue of eNAD/EDM affected horses and could serve as potential biomarkers for disease. AnimalsProceduresIsoprostane Study A: 14 Quarter horse foals (10 healthy foals and 4 eNAD/EDM affected foals) at 1 and 6 months of age. Isoprostane Study B: 17 eNAD/EDM affected and 10 unaffected horses1-4 years of age. Oxysterol study: eNAD/EDM affected (n=14, serum; n=11, CSF; n=10, spinal cord [SC]) and unaffected horses 1-4 years of age (n=12, serum; n=10, CSF; n=7, SC). Cerebrospinal fluid [F(2)IsoP] and [F4NP] were assessed using gas chromatography-negative ion chemical ionization mass spectrometry. Serum, CSF, and cervical SC [oxysterols] were quantified using high performance liquid chromatography mass spectrometry. Results were compared with respective -TOH concentrations. ResultsConclusions and Clinical ImportanceSpinal cord [7-ketocholesterol], [7-hydroxycholesterol], and [7-keto-27-hydrocholesterol] were higher in eNAD/EDM horses whereas [24-ketocholesterol] was lower. No significant difference was found in CSF [F(2)IsoP] and [F4NP], serum [oxysterols] and CSF [oxysterols] between eNAD/EDM affected and unaffected horses. No correlation was found between [F(2)IsoP], [F4NP], or [oxysterols] and respective [-TOH]. In the SC, targeted markers of cholesterol oxidation were significantly increased in horses with eNAD/EDM.