Plasticity following lesion: help and harm from the immune system

Area of Science:

• Neuroscience
• Immunology
• Regenerative Medicine

Background:

• The central nervous system (CNS) exhibits immune privilege, suppressing immune responses to minimize secondary damage after injury.
• This immune privilege, however, limits the beneficial effects of inflammation, such as clearing inhibitory myelin debris and adaptive immune system support for neuronal survival.
• Immune cells like macrophages and T cells play crucial roles in tissue repair, but their function is often inhibited in the CNS.

Purpose of the Study:

• To investigate the mechanisms suppressing immune cell function in the CNS after injury.
• To explore the role of death ligands, such as CD95L and TRAIL, in regulating immune cell apoptosis and brain cell death.
• To evaluate the potential of blocking death ligands for promoting CNS regeneration.

Main Methods:

• Analysis of immune cell behavior and apoptosis in the CNS following experimental lesions.
• Investigation of the expression and function of death ligands (CD95L, TRAIL) and their receptors on brain cells and immune cells.
• Exploration of the effects of death ligand blockade on immune cell survival and CNS tissue repair.

Main Results:

• The CNS actively suppresses immune cell recruitment and activation, hindering tissue repair.
• Death ligands, including CD95L, are upregulated in the injured CNS, leading to apoptosis of both immune cells and brain cells.
• T cells express death ligands, contributing to T cell-mediated apoptosis of brain cells.

Conclusions:

• Targeting death ligand pathways presents a promising therapeutic strategy for CNS injury.
• Blocking death ligands could simultaneously enhance beneficial immune cell functions and reduce detrimental immune-mediated damage.
• This approach may overcome the CNS's inherent failure to regenerate after axonal lesions, promoting functional recovery.