A Binary Cre Transgenic Approach Dissects Microglia and CNS Border-Associated Macrophages

Area of Science:

• Immunology
• Neuroscience
• Cell Biology

Background:

• Tissue macrophages exhibit significant developmental and molecular heterogeneity.
• Macrophages reside in distinct anatomical locations within tissues, performing diverse physiological and pathophysiological roles.
• Existing Cre recombinase-mediated mutagenesis models offer limited specificity for targeting distinct macrophage populations.

Purpose of the Study:

• To develop a novel binary transgenic system for precise targeting of specific tissue macrophage populations.
• To differentiate between parenchymal microglia and vasculature-associated macrophages in the brain.
• To analyze the functional and molecular differences between these distinct macrophage subsets.

Main Methods:

• Generation of Sall1^ncre: Cx₃cr1^ccre mice to target parenchymal microglia.
• Generation of Lyve1^ncre: Cx₃cr1^ccre mice to target vasculature-associated macrophages.
• Utilized in vivo imaging and RiboTag for translatome analysis of targeted cell populations.

Main Results:

• The binary transgenic system successfully achieved specific targeting of distinct macrophage populations.
• Sall1^ncre: Cx₃cr1^ccre mice specifically labeled parenchymal microglia.
• Lyve1^ncre: Cx₃cr1^ccre mice specifically labeled vasculature-associated macrophages in the brain and other tissues.
• Differential translatomes and responses to challenges were identified between the targeted macrophage subsets.

Conclusions:

• Binary transgenesis is a valuable tool for dissecting distinct tissue macrophage compartments.
• This approach enables a deeper understanding of the specific functions of microglia and other tissue macrophages.
• The developed system facilitates the study of macrophage heterogeneity and their roles in health and disease.