title: Oxidative stress induces mitochondrial dysfunction in a subset of autism lymphoblastoid cell lines in a well-matched case control cohort.
abstract: There is increasing recognition that mitochondrial dysfunction is associated with the autism spectrum disorders. However, little attention has been given to the etiology of mitochondrial dysfunction or how mitochondrial abnormalities might interact with other physiological disturbances associated with autism, such as oxidative stress. In the current study we used respirometry to examine reserve capacity, a measure of the mitochondrial ability to respond to physiological stress, in lymphoblastoid cell lines (LCLs) derived from children with autistic disorder (AD) as well as age and gender-matched control LCLs. We demonstrate, for the first time, that LCLs derived from children with AD have an abnormal mitochondrial reserve capacity before and after exposure to increasingly higher concentrations of 2,3-dimethoxy-1,4-napthoquinone (DMNQ), an agent that increases intracellular reactive oxygen species (ROS). Specifically, the AD LCLs exhibit a higher reserve capacity at baseline and a sharper depletion of reserve capacity when ROS exposure is increased, as compared to control LCLs. Detailed investigation indicated that reserve capacity abnormalities seen in AD LCLs were the result of higher ATP-linked respiration and maximal respiratory capacity at baseline combined with a marked increase in proton leak respiration as ROS was increased. We further demonstrate that these reserve capacity abnormalities are driven by a subgroup of eight (32%) of 25 AD LCLs. Additional investigation of this subgroup of AD LCLs with reserve capacity abnormalities revealed that it demonstrated a greater reliance on glycolysis and on uncoupling protein 2 to regulate oxidative stress at the inner mitochondria membrane. This study suggests that a significant subgroup of AD children may have alterations in mitochondrial function which could render them more vulnerable to a pro-oxidant microenvironment derived from intrinsic and extrinsic sources of ROS such as immune activation and pro-oxidant environmental toxicants. These findings are consistent with the notion that AD is caused by a combination of genetic and environmental factors.
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: Shannon
authors.initials: S
authors.lastname: Rose
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Frye
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: John
authors.initials: J
authors.lastname: Slattery
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Wynne
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: Marie
authors.initials: M
authors.lastname: Tippett
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: Oleksandra
authors.initials: O
authors.lastname: Pavliv
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: Stepan
authors.initials: S
authors.lastname: Melnyk
authors.affiliation: Department of Pediatrics, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, United States of America.
authors.forename: S Jill
authors.initials: SJ
authors.lastname: James
mesh_terms: D001321:Autistic Disorder / Q000378:metabolism* / Q000473:pathology; D016022:Case-Control Studies; D002460:Cell Line; D019069:Cell Respiration; D002648:Child; D002675:Child, Preschool; D005260:Female; D006019:Glycolysis; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D051336:Mitochondrial Membranes / Q000378:metabolism* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000378:metabolism; D009285:Naphthoquinones / Q000494:pharmacology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011522:Protons; D017382:Reactive Oxygen Species / Q000819:agonists / Q000378:metabolism; D000071246:Uncoupling Protein 2
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D009285:Naphthoquinones; D011522:Protons; D017382:Reactive Oxygen Species; C000604389:UCP2 protein, human; D000071246:Uncoupling Protein 2; C063002:2,3-dimethoxy-1,4-naphthoquinone