Motoneuronal inflammasome activation triggers excessive neuroinflammation and impedes regeneration after sciatic nerve injury

Journal of Neuroinflammation, 2022 · DOI: https://doi.org/10.1186/s12974-022-02427-9 · Published: March 1, 2022

Regenerative Medicine Immunology Neurology

Simple Explanation

Peripheral nerve injuries lead to inflammatory reactions that can hinder recovery if over-activated. The inflammasome pathway is a potent pro-inflammatory pathway, leading to the release of IL-1β. After sciatic nerve injury, NLRP3 inflammasome elements were upregulated in the spinal cord, leading to inflammasome assembly and IL-1β secretion. Inflammasome activation was found exclusively in motoneurons. Inhibition of this activation enhanced nerve regeneration.

Study Duration

8 weeks

Participants

135 male BALB/c mice

Evidence Level

Not specified

Key Findings

1
NLRP3 inflammasome components are markedly upregulated in the L4–L5 segments of the spinal cord in the first 3 days after sciatic nerve injury.
2
In the acute phase, inflammasome activation was found exclusively in affected motoneurons of the ventral horn.
3
Inhibition of neuronal inflammasome activation leads to a significant reduction of microgliosis and has a beneficial effect on recovery.

Research Summary

This study investigates the role of NLRP3 inflammasome activation in sciatic nerve injury, focusing on motoneurons, microgliosis, and regeneration. The central reaction to sciatic nerve injury begins with inflammasome activation in motoneurons, triggering inflammation and microglia activation. Inhibition of neuronal inflammasome activation reduces microgliosis and enhances recovery, indicating its detrimental role.

Practical Implications

Therapeutic Target Identification

P2X4 receptors and inflammasomes may serve as potential therapeutic targets in peripheral nerve injury.

Microgliosis Reduction

Inhibition of neuronal inflammasome activation could lead to new strategies for reducing microgliosis after nerve injuries.

Enhanced Axonal Recovery

Targeting neuronal inflammation may improve motoneuronal survival and motor axon regeneration after peripheral nerve coaptation.

Study Limitations

1
The study primarily focuses on male mice, potentially limiting generalizability to females.
2
The study acknowledges that while it focuses on central mechanisms, local inflammation in the injured nerve also contributes.
3
The study uses pharmacological inhibitors that have systemic effects, making it difficult to completely isolate spinal cord motoneuron effects.

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