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

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)-1?, and that infiltrating neutrophils and macrophages subsequently produce IL-1?. Infiltration of these cells is dramatically reduced in both IL-1?(-/-) and IL-1?(-/-) mice, but only IL-1?(-/-) 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-1?(-/-) mice compared with IL-1?(-/-) and wild-type mice. Accordingly, IL-1?(-/-) 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-1?(-/-) mice showed a transient increase in mature oligodendrocyte numbers, coinciding with increased IL-1? expression in wild-type animals. In adult mice, IL-1? 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-1?-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)-1?, which triggers neuroinflammation and locomotor defects. We uncovered that IL-1?(-/-) 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-1? 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.

SUBMITTER: Bastien D

PROVIDER: S-EPMC6605111 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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

Bastien Dominic D Bellver Landete Victor V Lessard Martine M Vallières Nicolas N Champagne Mathieu M Takashima Akira A Tremblay Marie-Ève MÈ Doyon Yannick Y Lacroix Steve S

The Journal of neuroscience : the official journal of the Society for Neuroscience 20150701 30

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 ...[more]

PMID: 26224856

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Project description:BackgroundThere is emerging evidence that astaxanthin plays a significant role in protecting neuro-cells from apoptosis after central nervous system injury. Our study examined the effects of astaxanthin on neuro-cell apoptosis after spinal cord injury.MethodsOne hundred and forty-four healthy adult Sprague-Dawley rats were randomly divided into the experimental group, control group, and sham operation group (n=48). Spinal cord injury was induced using the modified Allen method in the control group and the experimental group; while in the sham operation group, the lamina was removed without spinal cord injury. The rats in the experimental group were given astaxanthin (75 mg/kg) by gavage immediately after the operation, and in the other groups were given the same amount of olive oil. Motor function was assessed by blood-brain barrier (BBB) scores. The malondialdehyde (MDA) content and the activity of superoxide dismutase (SOD) at 24 h was determined after the operation. The apoptosis index (AI) was determined at 6, 24, and 48 h after the operation. At 48 h after the operation, we calculated the water content of the spinal cord, the lesion ratio of the spinal cord, the ultrastructure of the spinal cord, and the ultrastructure score.ResultsThe BBB scores of the control and experimental groups were significantly lower than the sham operation group at each postoperative time (P<0.05), and the BBB score of the experimental group was significantly higher than the control group at 1-4 weeks postoperatively (P<0.05). At 24 hours postoperatively, MDA content was highest in the control group and lowest in the sham operation group, while SOD activity was highest in the sham operation group and lowest in the control group (P<0.05). At each time point postoperatively, the sham operation group had the lowest AI and the control group had the highest AI (P<0.05). At 48 h after the operation, the water content and the lesion ratio of the spinal cord, and the ultrastructure score were the lowest in the sham operation group and the highest in the control group (P<0.05).ConclusionsAstaxanthin significantly improved the motor function of rats with spinal cord injury.

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Project description:BackgroundSpinal cord injury (SCI) induces a multitude of deleterious processes, including neuroinflammation and oxidative stress (OS) which contributed to neuronal damage and demyelination. Recent studies have suggested that increased formation of reactive oxygen species (ROS) and the consequent OS are critical events associated with SCI. However, there is still little information regarding the impact of these events on SCI. Astrocytes are key regulators of oxidative homeostasis in the CNS and astrocytic antioxidant responses promote the clearance of oxidants produced by neurons. Therefore, dysregulation of astrocyte physiology might largely contribute to oxidative damage. Nuclear factor erythroid 2-related factor 2 (Nrf2) is the main transcriptional regulator of cellular anti-oxidative stress responses.MethodsIn the current study, we hypothesized that astrocytic activation of Nrf2 protects the spinal cord post injury via suppression of neuroinflammation. Thus, using mice line with a GFAP-specific kelch-like ECH-associated protein 1 (Keap1)-deletion, we induced a hyperactivation of Nrf2 in astrocytes and further its effects on SCI outcomes. SCI-induction was performed in mice using the Infinite Horizon Spinal Cord Impactor with a force of 60 kdyn. To assess the quantitative pattern of Nrf2/ARE-activation, we included transgenic ARE-Luc mice. Data were analyzed with GraphPad Prism 8 (GraphPad Software Inc., San Diego, CA, USA). Brown-Forsythe test was performed to test for equal variances and normal distribution was tested with Shapiro-Wilk.ResultsIn ARE-Luc mice, a significant induction of luciferase-activity was observed as early as 1 day post-injury, indicating a functional role of Nrf2-activity at the epicenter of SCI. Furthermore, SCI induced loss of neurons and oligodendrocytes, demyelination and inflammation in wild type mice. The loss of myelin and oligodendrocytes was clearly reduced in Keap1 KO mice. In addition, Keap-1 KO mice showed a significantly better locomotor function and lower neuroinflammation responses compared to wild type mice.ConclusionsIn summary, our in vivo bioluminescence data showed Nrf2-ARE activation during primary phase of SCI. Furthermore, we found that cell specific hyperactivation of Nrf2 was sufficient to protect the spinal cord against injury which indicate a promising therapeutic approach for SCI-treatment.

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

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

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