title: Cu(II) enhances the effect of Alzheimer's amyloid-β peptide on microglial activation.
abstract: BACKGROUND
  Aggregated forms of amyloid-β (Aβ) peptides are important triggers for microglial activation, which is an important pathological component in the brains of Alzheimer's patients. Cu(II) ions are reported to be coordinated to monomeric Aβ, drive Aβ aggregation, and potentiate Aβ neurotoxicity. Here we investigated whether Cu(II) binding modulates the effect of Aβ on microglial activation and the subsequent neurotoxicity.
  
  
  METHODS
  Aβ peptides were incubated with Cu(II) at an equimolar ratio to obtain the Cu(II)-Aβ complex. Primary and BV-2 microglial cells were treated with Cu(II)-Aβ, Aβ, or Cu(II). The tumor necrosis factor-α (TNF-α) and nitric oxide levels in the media were determined. Extracellular hydrogen peroxide was quantified by a fluorometric assay with Amplex Red. Mitochondrial superoxide was detected by MitoSOX oxidation.
  
  
  RESULTS
  Incubation of Cu(II) with Aβ confers different chemical properties on the resulting complex. At the subneurotoxic concentrations, Cu(II)-Aβ (but not Aβ or Cu(II) alone) treatment induced an activating morphological phenotype of microglia and induced the microglial release of TNF-α and nitric oxide as well as microglia-mediated neuronal damage. Cu(II)-Aβ-triggered microglial activation was blocked by nuclear factor (NF)-κB inhibitors and was accompanied with NF-κB activation. Moreover, Cu(II)-Aβ induced hydrogen peroxide release, which was not affected by NADPH oxidase inhibitors. Mitochondrial superoxide production was increased after Cu(II)-Aβ stimulation. N-acetyl-cysteine, a scavenger of reactive oxygen species (ROS), inhibited Cu(II)-Aβ-elicited microglial release of TNF-α and nitric oxide as well as the microglia-mediated neurotoxic effect.
  
  
  CONCLUSIONS
  Our observations suggest that Cu(II) enhances the effect of Aβ on microglial activation and the subsequent neurotoxicity. The Cu(II)-Aβ-triggered microglial activation involves NF-κB activation and mitochondrial ROS production.
authors.affiliation: Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
authors.forename: Fengxiang
authors.initials: F
authors.lastname: Yu
authors.affiliation: Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Gong
authors.affiliation: Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
authors.forename: Zhuqin
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Qiu
authors.affiliation: Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
authors.forename: Yongyao
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Gao
authors.affiliation: Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China. yaoli@shsmu.edu.cn.
authors.forename: Hongzhuan
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China. lijuanpharm@163.com.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D003300:Copper / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008262:Macrophage Activation / Q000187:drug effects; D051379:Mice; D017628:Microglia / Q000187:drug effects*; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D009474:Neurons / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D016166:Free Radical Scavengers; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D009569:Nitric Oxide; D003300:Copper; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases