title: Comparing the potential renal protective activity of desferrioxamine B and the novel chelator desferrioxamine B-N-(3-hydroxyadamant-1-yl)carboxamide in a cell model of myoglobinuria.
abstract: Accumulating Mb (myoglobin) in the kidney following severe burns promotes oxidative damage and inflammation, which leads to acute renal failure. The potential for haem-iron to induce oxidative damage has prompted testing of iron chelators [e.g. DFOB (desferrioxamine B)] as renal protective agents. We compared the ability of DFOB and a DFOB-derivative {DFOB-AdAOH [DFOB-N-(3-hydroxyadamant-1-yl)carboxamide]} to protect renal epithelial cells from Mb insult. Loading kidney-tubule epithelial cells with dihydrorhodamine-123 before exposure to 100 μM Mb increased rhodamine-123 fluorescence relative to controls (absence of Mb), indicating increased oxidative stress. Extracellular Mb elicited a reorganization of the transferrin receptor as assessed by monitoring labelled transferrin uptake with flow cytometry and inverted fluorescence microscopy. Mb stimulated HO-1 (haem oxygenase-1), TNFα (tumour necrosis factor α), and both ICAM (intercellular adhesion molecule) and VCAM (vascular cell adhesion molecule) gene expression and inhibited epithelial monolayer permeability. Pre-treatment with DFOB or DFOB-AdAOH decreased Mb-mediated rhodamine-123 fluorescence, HO-1, ICAM and TNFα gene expression and restored monolayer permeability. MCP-1 (monocyte chemotactic protein 1) secretion increased in cells exposed to Mb-insult and this was abrogated by DFOB or DFOB-AdAOH. Cells treated with DFOB or DFOB-AdAOH alone showed no change in permeability, MCP-1 secretion or HO-1, TNFα, ICAM or VCAM gene expression. Similarly to DFOB, incubation of DFOB-AdAOH with Mb plus H2O2 yielded nitroxide radicals as detected by EPR spectroscopy, indicating a potential antioxidant activity in addition to metal chelation; Fe(III)-loaded DFOB-AdAOH showed no nitroxide radical formation. Overall, the chelators inhibited Mb-induced oxidative stress and inflammation and improved epithelial cell function. DFOB-AdAOH showed similar activity to DFOB, indicating that this novel low-toxicity chelator may protect the kidney after severe burns.
authors.affiliation: Discipline of Pathology, Redox Biology Group and Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Ludwig K
authors.initials: LK
authors.lastname: Groebler
authors.forename: Joe
authors.initials: J
authors.lastname: Liu
authors.forename: Anu
authors.initials: A
authors.lastname: Shanu
authors.forename: Rachel
authors.initials: R
authors.lastname: Codd
authors.forename: Paul K
authors.initials: PK
authors.lastname: Witting
mesh_terms: D000818:Animals; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology*; D003676:Deferoxamine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004285:Dogs; D004705:Endocytosis; D004847:Epithelial Cells / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D007684:Kidney Tubules / Q000166:cytology*; D015394:Molecular Structure; D009211:Myoglobin / Q000633:toxicity; D009212:Myoglobinuria / Q000188:drug therapy*
chemical_list: D002614:Chelating Agents; D009211:Myoglobin; D003676:Deferoxamine