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Hellenbrand DJ, Quinn CM, Piper ZJ, Morehouse CN, Fixel JA, Hanna AS. Inflammation after spinal cord injury: a review of the critical timeline of signaling cues and cellular infiltration. J Neuroinflammation 2021; 18:284. [PMID: 34876174 PMCID: PMC8653609 DOI: 10.1186/s12974-021-02337-2] [Citation(s) in RCA: 147] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/30/2021] [Indexed: 03/02/2023] Open
Abstract
Traumatic spinal cord injury (SCI) is a devastating neurological condition that results in a loss of motor and sensory function. Although extensive research to develop treatments for SCI has been performed, to date, none of these treatments have produced a meaningful amount of functional recovery after injury. The primary injury is caused by the initial trauma to the spinal cord and results in ischemia, oxidative damage, edema, and glutamate excitotoxicity. This process initiates a secondary injury cascade, which starts just a few hours post-injury and may continue for more than 6 months, leading to additional cell death and spinal cord damage. Inflammation after SCI is complex and driven by a diverse set of cells and signaling molecules. In this review, we utilize an extensive literature survey to develop the timeline of local immune cell and cytokine behavior after SCI in rodent models. We discuss the precise functional roles of several key cytokines and their effects on a variety of cell types involved in the secondary injury cascade. Furthermore, variations in the inflammatory response between rats and mice are highlighted. Since current SCI treatment options do not successfully initiate functional recovery or axonal regeneration, identifying the specific mechanisms attributed to secondary injury is critical. With a more thorough understanding of the complex SCI pathophysiology, effective therapeutic targets with realistic timelines for intervention may be established to successfully attenuate secondary damage.
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Affiliation(s)
- Daniel J Hellenbrand
- Department of Neurological Surgery, School of Medicine and Public Health (UWSMPH), University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA
| | - Charles M Quinn
- Department of Neurological Surgery, School of Medicine and Public Health (UWSMPH), University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA
| | - Zachariah J Piper
- Department of Neurological Surgery, School of Medicine and Public Health (UWSMPH), University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA
| | - Carolyn N Morehouse
- Department of Neurological Surgery, School of Medicine and Public Health (UWSMPH), University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA
| | - Jordyn A Fixel
- Department of Neurological Surgery, School of Medicine and Public Health (UWSMPH), University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA
| | - Amgad S Hanna
- Department of Neurological Surgery, School of Medicine and Public Health (UWSMPH), University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA.
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