A Microglia-Astrocyte Signaling Axis Regulates Astrocyte Piezo1 Expression and Inflammatory Responses

Area of Science:

• Neuroscience
• Cell Biology
• Immunology

Background:

• Astrocytes are crucial for brain homeostasis and are mechanosensitive.
• The role of astrocyte mechanosensation in brain disorders is understudied.
• Inflammatory triggers' effects on astrocytic mechanosensation remain largely unknown.

Purpose of the Study:

• To investigate how inflammatory triggers modulate the expression of the mechanosensitive ion channel Piezo1 in astrocytes.
• To elucidate the molecular mechanisms of astrocyte mechanosensation during pathological conditions.

Main Methods:

• Primary astrocyte and microglia cultures exposed to inflammatory stimuli (LPS, oAβ).
• Analysis of Piezo1 expression in astrocytes and microglia.
• Use of conditioned media from microglia to treat astrocytes.
• Microglial depletion in 5xFAD mice.
• Piezo1 activation (Yoda2) and knockdown experiments in astrocytes.

Main Results:

• Direct inflammatory stimuli minimally affected astrocytic Piezo1 expression.
• Microglia exposed to inflammatory stimuli upregulated Piezo1, which in turn upregulated astrocytic Piezo1 via released cytokines (IL-1α, IL-1β, TNF-α).
• Microglial depletion in vivo reduced astrocytic Piezo1 expression.
• Piezo1 activation modulated astrocyte inflammatory gene expression, while knockdown enhanced it, promoting microglial activation.

Conclusions:

• Astrocytic Piezo1 expression is regulated by microglia-derived inflammatory signals.
• This microglia-astrocyte signaling axis is physiologically relevant in pathological conditions.
• Astrocytic Piezo1 plays a context-dependent role in astrocyte reactivity and neuroinflammation.