Meningeal γδ T cell-derived IL-17 controls synaptic plasticity and short-term memory

Area of Science:

• Neuroimmunology
• Cognitive Neuroscience

Background:

• The brain's immune privilege concept is evolving, recognizing immune cell roles in neurophysiology.
• Mechanisms linking immunity to learning and memory are not fully understood.

Purpose of the Study:

• To investigate the role of immune cells and their products in regulating cognitive functions, specifically learning and memory.

Main Methods:

• Utilized mouse models lacking specific T cell subsets (γδ T cells) or key signaling molecules (IL-17).
• Assessed cognitive performance using spatial learning paradigms.
• Examined synaptic plasticity, including long-term potentiation (LTP) in the hippocampus.
• Analyzed the impact of IL-17 on glial cell-derived neurotrophic factor (GDNF) production.

Main Results:

• Mice deficient in γδ T cells or IL-17 showed impaired short-term memory but intact long-term memory.
• Reduced glutamatergic synaptic plasticity and hippocampal LTP were observed in IL-17-deficient mice.
• IL-17 promoted glial production of brain-derived neurotrophic factor (BDNF).
• Exogenous BDNF administration rescued synaptic and memory deficits in IL-17-deficient mice.

Conclusions:

• A novel subset of meningeal γδ T cells produces noninflammatory IL-17, essential for cognitive function.
• IL-17 plays a critical role in regulating short-term memory and synaptic plasticity via BDNF.
• This study reveals a significant link between the immune system and cognitive processes, particularly memory formation.