Single-cell profiling identifies myeloid cell subsets with distinct fates during neuroinflammation

Area of Science:

• Neuroimmunology
• Cellular and Molecular Neuroscience
• Innate Immunity

Background:

• The healthy central nervous system (CNS) contains diverse innate immune cells, primarily parenchymal and non-parenchymal macrophages.
• Inflammatory conditions in the CNS lead to the recruitment of circulating myeloid cells, increasing immune cell complexity.
• The specific disease-associated myeloid subsets, their transcriptional profiles, and dynamics during CNS pathology remain largely uncharacterized.

Purpose of the Study:

• To comprehensively characterize unappreciated myeloid subsets in various CNS compartments during neuroinflammation.
• To investigate the transcriptional profiles and dynamic behavior of these myeloid subsets.
• To understand the functional roles of endogenous CNS tissue macrophages during inflammatory processes.

Main Methods:

• Deep single-cell transcriptome analysis.
• Fate mapping and in vivo imaging techniques.
• Clonal analysis and transgenic mouse models were employed.

Main Results:

• Identified and characterized previously unrecognized myeloid subsets within the CNS during neuroinflammation.
• Observed that CNS macrophage subsets undergo self-renewal during inflammation.
• Demonstrated a shift from random proliferation to clonal expansion in myeloid cells during inflammatory states.
• Functional studies indicated that endogenous CNS tissue macrophages are redundant for antigen presentation.

Conclusions:

• Neuroinflammation significantly alters the diversity and dynamics of myeloid cell populations in the CNS.
• Endogenous CNS macrophages play a limited role in antigen presentation, suggesting specialized functions.
• This research provides critical insights into the heterogeneity and behavior of the brain's innate immune system during disease.