Oxidative stress induces mitochondrial dysfunction in a subset of autism lymphoblastoid cell lines in a well-matched case control cohort

PLoS One. 2014 Jan 8;9(1):e85436. doi: 10.1371/journal.pone.0085436. eCollection 2014.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autistic Disorder / metabolism*
  • Autistic Disorder / pathology
  • Case-Control Studies
  • Cell Line
  • Cell Respiration
  • Child
  • Child, Preschool
  • Female
  • Glycolysis
  • Humans
  • Ion Channels / metabolism
  • Lymphocytes / metabolism*
  • Lymphocytes / pathology
  • Male
  • Mitochondria / metabolism*
  • Mitochondria / pathology
  • Mitochondrial Membranes / metabolism*
  • Mitochondrial Membranes / pathology
  • Mitochondrial Proteins / metabolism
  • Naphthoquinones / pharmacology
  • Oxidation-Reduction
  • Oxidative Stress*
  • Protons*
  • Reactive Oxygen Species / agonists
  • Reactive Oxygen Species / metabolism
  • Uncoupling Protein 2

Substances

  • Ion Channels
  • Mitochondrial Proteins
  • Naphthoquinones
  • Protons
  • Reactive Oxygen Species
  • UCP2 protein, human
  • Uncoupling Protein 2
  • 2,3-dimethoxy-1,4-naphthoquinone

Grant support

This research was funded by the National Institute for Child Health and Development (SJJ), the Arkansas Biosciences Institute (REF, SJJ), and the Jane Botsford Johnson Foundation (REF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.