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Baldacchino K, Peveler WJ, Lemgruber L, Smith RS, Scharler C, Hayden L, Komarek L, Lindsay SL, Barnett SC, Edgar JM, Linington C, Thümmler K. Myelinated axons are the primary target of hemin-mediated oxidative damage in a model of the central nervous system. Exp Neurol 2022; 354:114113. [PMID: 35569511 DOI: 10.1016/j.expneurol.2022.114113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/29/2022] [Accepted: 05/08/2022] [Indexed: 12/01/2022]
Abstract
Iron released from oligodendrocytes during demyelination or derived from haemoglobin breakdown products is believed to amplify oxidative tissue injury in multiple sclerosis (MS). However, the pathophysiological significance of iron-containing haemoglobin breakdown products themselves is rarely considered in the context of MS and their cellular specificity and mode of action remain unclear. Using myelinating cell cultures, we now report the cytotoxic potential of hemin (ferriprotoporphyrin IX chloride), a major degradation product of haemoglobin, is 25-fold greater than equimolar concentrations of free iron in myelinating cultures; a model that reproduces the complex multicellular environment of the CNS. At low micro molar concentrations (3.3 - 10 μM) we observed hemin preferentially binds to myelin and axons to initiate a complex detrimental response that results in targeted demyelination and axonal loss but spares neuronal cell bodies, astrocytes and the majority of oligodendroglia. Demyelination and axonal loss in this context are executed by a combination of mechanisms that include iron-dependent peroxidation by reactive oxygen species (ROS) and ferroptosis. These effects are microglial-independent, do not require any initiating inflammatory insult and represent a direct effect that compromises the structural integrity of myelinated axons in the CNS. Our data identify hemin-mediated demyelination and axonal loss as a novel mechanism by which intracerebral degradation of haemoglobin may contribute to lesion development in MS.
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Affiliation(s)
- Karl Baldacchino
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - William J Peveler
- WestCHEM, School of Chemistry, University of Glasgow, Joseph Black Building, G12 8QQ Glasgow, UK
| | - Leandro Lemgruber
- Glasgow Imaging Facility, Institute of Infection, Immunity and Inflammation, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Rebecca Sherrard Smith
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - Cornelia Scharler
- Institute of Experimental and Clinical Cell Therapy, Paracelsus Medical University, Salzburg, Austria
| | - Lorna Hayden
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - Lina Komarek
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - Susan L Lindsay
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - Susan C Barnett
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - Julia M Edgar
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - Christopher Linington
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom
| | - Katja Thümmler
- Institute of Infection, Immunity and Inflammation, University of Glasgow, G12 8TA Glasgow, United Kingdom.
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