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IL-1 receptor antagonist prevents apoptosis and caspase-3 activation after spinal cord injury
1Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77555-0652, USA. Olnesic@utmb.edu
Abstract:
One of the consequences of cytokine-orchestrated inflammation after CNS trauma is apoptosis. Our hypothesis is that cell death in the spinal cord after injury results in part from increased synthesis and release of IL-1beta. Using a ribonuclease protection assay, we demonstrated that there is increased transient expression of IL-1beta mRNA and, by using IL-1beta protein ELISA assay, that there are increased IL-1beta protein levels in the contused rat spinal cord, initially localized to the impact region of the spinal cord (segment T8). Using an ELISA cell death assay, we showed that there is apoptosis in the spinal cord 72 h after injury, a finding that was confirmed by measuring caspase-3 activity, which also significantly increased at the site of injury 72 h after trauma. Treatment of the contused spinal cord at the site of injury with the IL-1 receptor antagonist (rmIL-lra, 750 ng/mL) for 72 h using an osmotic minipump completely abolished the increases in contusion-induced apoptosis and caspase-3 activity.
Insights
Spinal cord injury triggers inflammation and apoptosis, partly due to increased interleukin-1 beta (IL-1beta). Blocking IL-1beta with an antagonist significantly reduced cell death and caspase-3 activity after trauma.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Cytokine-mediated inflammation is a key consequence of central nervous system (CNS) trauma.
- Apoptosis, or programmed cell death, is a significant factor in secondary damage following spinal cord injury.
Purpose of the Study:
- To investigate the role of interleukin-1 beta (IL-1beta) in apoptosis after spinal cord injury.
- To determine if inhibiting IL-1beta signaling can mitigate post-traumatic cell death.
Main Methods:
- Utilized ribonuclease protection assays to measure IL-1beta mRNA expression.
- Employed ELISA assays to quantify IL-1beta protein levels and assess cell death.
- Measured caspase-3 activity as an indicator of apoptosis.
- Administered recombinant IL-1 receptor antagonist (rmIL-1ra) via osmotic minipump.
Main Results:
- Demonstrated transient increases in IL-1beta mRNA and protein levels in the contused spinal cord.
- Confirmed significant apoptosis and elevated caspase-3 activity at the injury site 72 hours post-trauma.
- Showed that rmIL-1ra treatment completely abolished the increases in apoptosis and caspase-3 activity.
Conclusions:
- Increased IL-1beta synthesis and release contribute to apoptosis following spinal cord injury.
- IL-1beta receptor antagonism is a potential therapeutic strategy to reduce cell death after CNS trauma.