Different Contacted Cell Types Contribute to Acquiring Different Properties in Brain Microglial Cells upon...

Area of Science:

• Neuroscience
• Cell Biology
• Immunology

Background:

• Microglial cells (MGs) are key immune cells in the brain.
• MGs interact with various brain cells, including astrocytes (ACs), pericytes (PCs), and endothelial cells (ECs).
• The specific impact of these cell-cell interactions on microglial phenotypes remains largely unknown.

Purpose of the Study:

• To investigate how ACs, PCs, and ECs influence microglial cell traits through direct cell-cell contact.
• To identify common and cell type-specific effects of these interactions on MGs.
• To explore the role of gap junction protein alpha 1 (Gja1) in mediating these interactions.

Main Methods:

• Coculturing of mouse brain-derived MGs with ACs, PCs, or ECs to enable direct cell contact.
• Microarray analysis to assess changes in gene expression.
• Immunohistochemistry and immunofluorescence to confirm protein expression and intercellular communication.
• Fluorescence-activated cell sorting (FACS) to analyze cell transfer.
• Gja1 inhibition experiments to determine its role.

Main Results:

• ACs and PCs increased MG numbers, while ECs decreased them in a dose-dependent manner.
• Cell-cell contact with ACs, PCs, and ECs altered MG cell fate-related genes, including those involved in cell cycle, proliferation, growth, death, and apoptosis.
• Gap junction protein alpha 1 (Gja1) was upregulated in MGs upon co-incubation with ACs, PCs, or ECs.
• Gja1 inhibition demonstrated that ACs and PCs positively regulate MG numbers, whereas ECs negatively regulate them.

Conclusions:

• Astrocytes, pericytes, and endothelial cells exert both shared and distinct cell type-specific effects on microglial cells via intercellular interactions.
• These interactions significantly influence microglial cell numbers and gene expression profiles.
• The findings highlight that microglial phenotypes are context-dependent, varying based on their surrounding cell types in the brain.