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Interleukin-6 contributes to CNS axon regeneration upon inflammatory stimulation
M Leibinger1, A Müller, P Gobrecht
1Department of Neurology, Heinrich-Heine-University of Düsseldorf, Merowingerplatz 1a, Düsseldorf, Germany.
Cell Death & Disease
|April 27, 2013
Summary
Interleukin-6 (IL-6) promotes optic nerve regeneration in mature retinal ganglion cells (RGCs) by enhancing neurite outgrowth and reducing growth inhibitors. IL-6 is crucial for inflammatory stimulation-mediated axon repair.
Area of Science:
- Neuroscience
- Ophthalmology
- Regenerative Medicine
Background:
- Mature retinal ganglion cells (RGCs) typically fail to regenerate injured axons and undergo apoptosis.
- Inflammatory stimulation (IS) promotes neuroprotection and optic nerve axon regeneration.
- Ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) are known mediators of IS effects.
Purpose of the Study:
- To investigate the role of interleukin-6 (IL-6) as a contributing factor in IS-mediated RGC axon regeneration.
- To determine the mechanisms by which IL-6 influences RGC neurite outgrowth and growth inhibition.
Main Methods:
- Assessed IL-6 expression in retinal tissue after optic nerve injury and IS.
- Treated cultured RGCs with IL-6 or its receptor agonist, examining neurite outgrowth and growth inhibition pathways (JAK/STAT3, PI3K/Akt, mTOR).
- Evaluated IL-6's in vivo effects on RGCs and optic nerve regeneration in wild-type and IL-6-ablated mice.
Main Results:
- IL-6 expression was significantly induced in the retina post-injury and IS; RGCs expressed the IL-6 receptor.
- IL-6 treatment increased RGC neurite outgrowth via JAK/STAT3 and PI3K/Akt pathways and reduced myelin-mediated growth inhibition via mTOR.
- In vivo, IL-6 promoted RGC axon regeneration beyond the lesion site, while IL-6 genetic ablation impaired IS-mediated regeneration and myelin disinhibition.
Conclusions:
- IL-6 is a key mediator of IS-induced optic nerve regeneration, contributing to neuroprotection and axon regrowth.
- IL-6's ability to reduce myelin-mediated growth inhibition is a significant feature of its regenerative effects.
- IL-6 administration or receptor activation represents a promising therapeutic strategy for enhancing optic nerve regeneration.
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