title: Iron accumulation and neurotoxicity in cortical cultures treated with holotransferrin.
abstract: Nonheme iron accumulates in CNS tissue after ischemic and hemorrhagic insults and may contribute to cell loss. The source of this iron has not been precisely defined. After blood-brain barrier disruption, CNS cells may be exposed to plasma concentrations of transferrin-bound iron (TBI), which exceed that in the CSF by over 50-fold. In this study, the hypothesis that these concentrations of TBI produce cell iron accumulation and neurotoxicity was tested in primary cortical cultures. Treatment with 0.5-3mg/ml holotransferrin for 24h resulted in the loss of 20-40% of neurons, associated with increases in malondialdehyde, ferritin, heme oxygenase-1, and iron; transferrin receptor-1 expression was reduced by about 50%. Deferoxamine, 2,2'-bipyridyl, Trolox, and ascorbate prevented all injury, but apotransferrin was ineffective. Cell TBI accumulation was significantly reduced by deferoxamine, 2,2'-bipyridyl, and apotransferrin, but not by ascorbate or Trolox. After treatment with (55)Fe-transferrin, approximately 40% of cell iron was exported within 16h. Net export was increased by deferoxamine and 2,2'-bipyridyl, but not by apotransferrin. These results suggest that downregulation of transferrin receptor-1 expression is insufficient to prevent iron-mediated death when neurons are exposed to plasma concentrations of TBI. Chelator therapy may be beneficial for acute CNS injuries associated with loss of blood-brain barrier integrity.
authors.affiliation: Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
authors.forename: Jing
authors.initials: J
authors.lastname: Chen-Roetling
authors.forename: Wenpei
authors.initials: W
authors.lastname: Liu
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Regan
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D027682:Cation Transport Proteins / Q000096:biosynthesis; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005293:Ferritins / Q000096:biosynthesis; D051547:Heme Oxygenase-1 / Q000096:biosynthesis; D006801:Humans; D007501:Iron / Q000097:blood / Q000378:metabolism* / Q000633:toxicity*; D007502:Iron Chelating Agents / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011990:Receptors, Transferrin / Q000096:biosynthesis; D014168:Transferrin / Q000494:pharmacology*; D000098742:Ferroportin
chemical_list: D000975:Antioxidants; D027682:Cation Transport Proteins; D007502:Iron Chelating Agents; D011990:Receptors, Transferrin; C480029:Tfrc protein, mouse; D014168:Transferrin; C110714:holotransferrin; D000098742:Ferroportin; D005293:Ferritins; D007501:Iron; D051547:Heme Oxygenase-1