Ceruloplasmin Protects Injured Spinal Cord from Iron-Mediated Oxidative Damage

Abstract

CNS injury-induced hemorrhage and tissue damage leads to excess iron, which can cause secondary degeneration. The mechanisms that handle this excess iron are not fully understood. We report that spinal cord contusion injury (SCI) in mice induces an "iron homeostatic response" that partially limits iron-catalyzed oxidative damage. We show that ceruloplasmin (Cp), a ferroxidase that oxidizes toxic ferrous iron, is important for this process. SCI in Cp-deficient mice demonstrates that Cp detoxifies and mobilizes iron and reduces secondary tissue degeneration and functional loss. Our results provide new insights into how astrocytes and macrophages handle iron after SCI. Importantly, we show that iron chelator treatment has a delayed effect in improving locomotor recovery between 3 and 6 weeks after SCI. These data reveal important aspects of the molecular control of CNS iron homeostasis after SCI and suggest that iron chelator therapy may improve functional recovery after CNS trauma and hemorrhagic stroke.

Inhibition of the Ca2+-Dependent K+Channel,KCNN4/KCa3.1, Improves Tissue Protection and Locomotor Recovery after Spinal Cord Injury

“…Finally, reducing iNOS expression has been associated with neuroprotection and better functional outcomes after SCI (Isaksson et al, 2005;Ló pez-Vales et al, 2006). iNOS is not expressed in the healthy adult CNS, but after spinal cord injury, proinflammatory cytokines can induce it in microglia and astrocytes (Murphy, 2000;Xu et al, 2001;Rathore et al, 2008), and its expression is seen as late as 14 d after injury. The subsequent production of NO and NO-derived reactive nitrogen species (e.g., peroxynitrite) can kill neurons by inhibiting mitochondrial cytochrome oxidase (Brown and Cooper, 1994;Bal-Price and Brown, 2001), and by causing lipid peroxidation and DNA oxidative damage (Bolaños et al, 1995;Scott et al, 1999;Liu et al, 2000;Szabó , 2003).…”

“…7C) (p Ͻ 0.05). This time was chosen because iNOS has been shown previously to be expressed up to 7-14 d after SCI (Ló pez-Vales et al, 2005;Yang et al, 2007;Rathore et al, 2008), and this is a time point when one sees robust astrocyte and macrophage responses. iNOS can be generated by several pathways, only one of which is likely to be blocked by TRAM-34, and this might account for the partial reduction seen.…”

Iron Efflux from Oligodendrocytes Is Differentially Regulated in Gray and White Matter

“…Cells were stained for 30 min at room temperature with mouse anti-A2B5 (1:100; R&D Systems), mouse anti-O4 (1:100; Millipore Bioscience Research Reagents) or mouse anti-Gal-C (1:100; Millipore Bioscience Research Reagents), and rabbit anti-Heph (1:400; Chris Vulpe, University of California, Berkeley, Berkeley, CA) or rabbit anti-Fpn (1:200; Alpha Diagnostics). Primary antibodies were visualized with rhodamineconjugated goat anti-mouse IgG (1:400; Jackson ImmunoResearch) and Al- (Jeong and David, 2006;Rathore et al, 2008). Sections were coverslipped with DAPI-containing medium and viewed with a Zeiss Axioskop 2 Plus microscope.…”

Mitogen-Activated Protein Kinase-Activated Protein Kinase 2 (MK2) Contributes to Secondary Damage after Spinal Cord Injury

“…Tissue sections were first blocked with an anti-mouse IgG antibody (1:100; Jackson ImmunoResearch) for 2 h when immunostaining with an antibody generated in mouse. A rabbit polyclonal antibody against 3-nitrotyrosine (1:400; Millipore) was used to identify nitric oxide-mediated damage and its binding was revealed using HRP-conjugated secondary antibody and the chromogen diaminobenzidine, as previously described (Rathore et al, 2008). Tissue sections were stained with Luxol Fast Blue (LFB) to assess myelin loss and with cresyl violet to assess neuron loss in the ventral horn.…”