Activated Microglia-Derived Extracellular Vesicles Elicit a Pro-Inflammatory Astrocytic Response via Cargo-Dependent...

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Neuroinflammation involves microglia and astrocytes coordinating responses via cytokines and extracellular vesicles (EVs).
• The precise mechanisms of EV-mediated communication between these glial cells in neuroinflammation remain unclear.

Purpose of the Study:

• To investigate how EVs derived from activated microglia (ABEVs) affect astrocyte polarization and inflammatory signaling.
• To analyze the protein cargo of different EV subtypes (microvesicles and exosomes) to understand their functional roles.

Main Methods:

• Activated BV-2 microglial cells were used to isolate microvesicles (ABMVs) and exosomes (ABEXs).
• Primary mouse astrocytes were treated with lipopolysaccharide (LPS), ABMVs, or ABEXs.
• Gene expression of astrocyte markers and inflammatory mediators was quantified.
• EV protein cargo was analyzed using mass spectrometry and proteomics.

Main Results:

• Activated microglia-derived exosomes (ABEXs) mimicked LPS-induced astrocyte reactivity, upregulating markers like C3 and Serpina3n.
• ABEXs also increased inflammatory mediators (Lcn2, Il-1β) in astrocytes, partially replicating microglial inflammatory effects.
• Proteomic analysis revealed distinct cargo profiles, with ABEXs enriched in proteins related to NOD-like receptor signaling and ribosome biogenesis compared to ABMVs.

Conclusions:

• Microglia-derived EVs modulate astrocyte polarization and cytokine profiles in a cargo-dependent manner.
• Exosomes play a more significant role than microvesicles in mediating these microglial-astrocyte communication effects.
• These findings identify novel targets for modulating neuroinflammation through EV-based mechanisms.