title: Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase.
abstract: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown.
  
  
  
  Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone.
  
  
  
  In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100μg/cm2induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10μg/cm2) and rotenone (2nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91phox, p47phoxand p40phox); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47phoxand p67phoxtranslocation assembling active NADPH oxidase.
  
  
  
  ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our findings delineated the potential role of ultrafine particles alone and in combination with pesticide rotenone in the pathogenesis of PD.
authors.affiliation: Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191, China.
authors.forename: Yinxi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191, China.
authors.forename: Huifeng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191, China.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Beijing Center for Physical & Chemical Analysis, Beijing 100089, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Wei
authors.affiliation: School of Life Science, Beijing Normal University, Beijing 100875, China.
authors.forename: Yutong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Translational Medicine, Xiamen Institute of Rare Earth Materials, Chinese Academy of Sciences, Xiamen 361024, China.
authors.forename: Jieying
authors.initials: J
authors.lastname: Liao
authors.affiliation: Model Animal Research Center of Nanjing University, Nanjing 211800, China.
authors.forename: Hui-Ming
authors.initials: HM
authors.lastname: Gao
authors.affiliation: Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191, China. Electronic address: hardhui@gmail.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhou
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018920:Coculture Techniques; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D019255:NADPH Oxidases / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D052638:Particulate Matter; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D012402:Rotenone / Q000633:toxicity*; D012828:Silicones / Q000633:toxicity*; D053260:Soot / Q000633:toxicity*
chemical_list: D052638:Particulate Matter; D017382:Reactive Oxygen Species; D012828:Silicones; D053260:Soot; D012402:Rotenone; D019255:NADPH Oxidases
keywords: NADPH oxidase; Neuroinflammation; Parkinson's disease; Particulate matter; Rotenone; Ultrafine carbon black