Act1 mediates IL-17-induced EAE pathogenesis selectively in NG2+ glial cells.

Area of Science:

• Neuroimmunology
• Cellular and Molecular Neuroscience

Background:

• Interleukin 17 (IL-17) is a key cytokine produced by Th17 cells.
• NF-κB activator 1 (Act1) is essential for IL-17 receptor signaling.
• Previous studies showed Act1 deletion in neuroectodermal lineage attenuates experimental autoimmune encephalomyelitis (EAE) severity.

Purpose of the Study:

• To investigate the specific cell types within the neuroectodermal lineage responsible for mediating IL-17 effects in EAE.
• To identify the primary cellular targets of IL-17 signaling in the central nervous system (CNS) during EAE.

Main Methods:

• Utilized conditional knockout mice to delete Act1 in specific neural cell populations (neurons, oligodendrocytes, astrocytes, NG2(+) glia).
• Assessed EAE disease severity following Act1 deletion in different cell types.
• Investigated IL-17-induced inflammatory mediator expression in NG2(+) glial cells.
• Examined the effects of IL-17 on oligodendrocyte lineage cell maturation and survival in vitro.

Main Results:

• Deletion of Act1 in neurons, mature oligodendrocytes, or astrocytes did not significantly impact EAE severity.
• Act1 deletion specifically in NG2(+) glia markedly reduced EAE severity.
• IL-17 induced inflammatory mediator expression in NG2(+) glial cells.
• IL-17 inhibited oligodendrocyte lineage cell maturation and survival in vitro.

Conclusions:

• NG2(+) glia are identified as the major CNS cellular targets of IL-17 in the context of EAE.
• IL-17 exhibits direct toxicity towards oligodendrocyte lineage cells, impacting their maturation and survival.
• These findings suggest a direct link between neuroinflammation and neurodegeneration in conditions like multiple sclerosis.