Peripherally derived myeloid cells induce disease-dependent phenotypic changes in microglia.

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Peripherally derived myeloid cells infiltrate the central nervous system (CNS) during injury and disease, contributing to neuroinflammation.
• The phenotype and function of these infiltrating cells vary with injury type and disease phase, influencing interactions with resident microglia.

Purpose of the Study:

• To develop an in vitro system for investigating communication between peripheral myeloid cells and microglia.
• To uncover differences in myeloid cell-microglia crosstalk based on disease model (experimental autoimmune encephalomyelitis [EAE] and cerebral ischemia [pMCAO]) and disease timing.

Main Methods:

• Isolation of peripheral myeloid cells from EAE and pMCAO mouse models at different time points post-disease onset.
• Co-culture of isolated peripheral myeloid cells with primary microglia to assess phenotypic and gene expression changes.
• Analysis of microglial morphology and gene expression related to inflammatory and phagocytic pathways.

Main Results:

• Peripheral myeloid cells from acute EAE induced microglial morphological changes and increased inflammatory gene expression.
• Peripheral myeloid cells from chronic pMCAO induced inflammatory and phagocytic gene expression changes in microglia without altering morphology.
• Identified disease-specific and time-dependent alterations in myeloid cell-microglia interactions.

Conclusions:

• The impact of infiltrating myeloid cells on microglia is context-dependent, varying by disease model and phase.
• The developed in vitro assay is a valuable tool for studying myeloid cell interactions in various CNS neuroinflammatory conditions.
• Findings highlight the importance of considering disease context and timing for myeloid cell-mediated neuroinflammation and potential therapeutic strategies.