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Gallego-Delgado P, James R, Browne E, Meng J, Umashankar S, Tan L, Picon C, Mazarakis ND, Faisal AA, Howell OW, Reynolds R. Neuroinflammation in the normal-appearing white matter (NAWM) of the multiple sclerosis brain causes abnormalities at the nodes of Ranvier. PLoS Biol 2020; 18:e3001008. [PMID: 33315860 PMCID: PMC7769608 DOI: 10.1371/journal.pbio.3001008] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 12/28/2020] [Accepted: 11/20/2020] [Indexed: 01/02/2023] Open
Abstract
Changes to the structure of nodes of Ranvier in the normal-appearing white matter (NAWM) of multiple sclerosis (MS) brains are associated with chronic inflammation. We show that the paranodal domains in MS NAWM are longer on average than control, with Kv1.2 channels dislocated into the paranode. These pathological features are reproduced in a model of chronic meningeal inflammation generated by the injection of lentiviral vectors for the lymphotoxin-α (LTα) and interferon-γ (IFNγ) genes. We show that tumour necrosis factor (TNF), IFNγ, and glutamate can provoke paranodal elongation in cerebellar slice cultures, which could be reversed by an N-methyl-D-aspartate (NMDA) receptor blocker. When these changes were inserted into a computational model to simulate axonal conduction, a rapid decrease in velocity was observed, reaching conduction failure in small diameter axons. We suggest that glial cells activated by pro-inflammatory cytokines can produce high levels of glutamate, which triggers paranodal pathology, contributing to axonal damage and conduction deficits. Current thinking on the mechanisms by which multiple sclerosis gives rise to cumulative neurological disability revolves largely around focal lesions of inflammation and demyelination. However, some of the debilitating symptoms, such as severe fatigue, might be better explained by a more diffuse pathology. This study shows that paranodes in the white matter become abnormal as a result of neuroinflammation, which may be the result of the action of cytokines that cause glia to release glutamate.
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Affiliation(s)
- Patricia Gallego-Delgado
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Rachel James
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Eleanor Browne
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Joanna Meng
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Swetha Umashankar
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Li Tan
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Carmen Picon
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Nicholas D. Mazarakis
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - A. Aldo Faisal
- Department of Bioengineering, Faculty of Engineering, Imperial College London, London, United Kingdom
- Department of Computing, Faculty of Engineering, Imperial College London, London, United Kingdom
- Data Science Institute, Imperial College London, London, United Kingdom
| | - Owain W. Howell
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
- Institute of Life Sciences, Swansea University Medical School, Swansea University, Swansea, Wales
| | - Richard Reynolds
- Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
- Centre for Molecular Neuropathology, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- * E-mail:
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