IL-1α Gene Deletion Protects Oligodendrocytes after Spinal Cord Injury through Upregulation of the Survival Factor Tox3.

TitleIL-1α Gene Deletion Protects Oligodendrocytes after Spinal Cord Injury through Upregulation of the Survival Factor Tox3.
Publication TypeJournal Article
Year of Publication2015
AuteursBastien, D, Landete, VBellver, Lessard, M, Vallières, N, Champagne, M, Takashima, A, Tremblay, M-È, Doyon, Y, Lacroix, S
JournalJ Neurosci
Volume35
Issue30
Pagination10715-30
Date Published2015 Jul 29
ISSN1529-2401
KeywordsAnimals, Cell Line, Disease Models, Animal, Female, Flow Cytometry, Gene Deletion, Humans, Immunoblotting, Immunohistochemistry, Interleukin-1alpha, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Microscopy, Confocal, Nerve Degeneration, Oligodendroglia, Oligonucleotide Array Sequence Analysis, Real-Time Polymerase Chain Reaction, Receptors, Progesterone, Recovery of Function, Spinal Cord Injuries, Up-Regulation
Abstract

UNLABELLED: Spinal cord injury (SCI) causes the release of danger signals by stressed and dying cells, a process that leads to neuroinflammation. Evidence suggests that inflammation plays a role in both the damage and repair of injured neural tissue. We show that microglia at sites of SCI rapidly express the alarmin interleukin (IL)-1α, and that infiltrating neutrophils and macrophages subsequently produce IL-1β. Infiltration of these cells is dramatically reduced in both IL-1α(-/-) and IL-1β(-/-) mice, but only IL-1α(-/-) mice showed rapid (at day 1) and persistent improvements in locomotion associated with reduced lesion volume. Similarly, intrathecal administration of the IL-1 receptor antagonist anakinra restored locomotor function post-SCI. Transcriptome analysis of SCI tissue at day 1 identified the survival factor Tox3 as being differentially regulated exclusively in IL-1α(-/-) mice compared with IL-1β(-/-) and wild-type mice. Accordingly, IL-1α(-/-) mice have markedly increased Tox3 levels in their oligodendrocytes, beginning at postnatal day 10 (P10) and persisting through adulthood. At P10, the spinal cord of IL-1α(-/-) mice showed a transient increase in mature oligodendrocyte numbers, coinciding with increased IL-1α expression in wild-type animals. In adult mice, IL-1α deletion is accompanied by increased oligodendrocyte survival after SCI. TOX3 overexpression in human oligodendrocytes reduced cellular death under conditions mimicking SCI. These results suggest that IL-1α-mediated Tox3 suppression during the early phase of CNS insult plays a crucial role in secondary degeneration.SIGNIFICANCE STATEMENT: The mechanisms underlying bystander degeneration of neurons and oligodendrocytes after CNS injury are ill defined. We show that microglia at sites of spinal cord injury (SCI) rapidly produce the danger signal interleukin (IL)-1α, which triggers neuroinflammation and locomotor defects. We uncovered that IL-1α(-/-) mice have markedly increased levels of the survival factor Tox3 in their oligodendrocytes, which correlates with the protection of this cell population, and reduced lesion volume, resulting in unprecedented speed, level, and persistence of functional recovery after SCI. Our data suggest that central inhibition of IL-1α or Tox3 overexpression during the acute phase of a CNS insult may be an effective means for preventing the loss of neurological function in SCI, or other acute injuries such as ischemia and traumatic brain injuries.

DOI10.1523/JNEUROSCI.0498-15.2015
Alternate JournalJ. Neurosci.
PubMed ID26224856
Grant ListMOP-84558 / / Canadian Institutes of Health Research / Canada