BioProject

Microglia are resident immune cells of the central nervous system, yet their functions far exceed those related to immunology. More...

Microglia are resident immune cells of the central nervous system, yet their functions far exceed those related to immunology. From pruning neural synapses during development to preventing excessive neural activity throughout life, microglia are intimately involved in the brain’s most basic processes. Studies have reported a close interaction between microglia and endothelial cells, as well as both helpful and harmful roles for microglia at the blood-brain barrier (BBB) in the context of disease. However, much less work has been done to understand microglia-endothelial cell interactions in the healthy brain. Here, we aim to determine the role of microglia at the healthy BBB. We used the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 to deplete microglia and analyzed BBB ultrastructure, permeability, and transcriptome. Interestingly, we found that, despite their direct contact with endothelial cells, microglia are not necessary for maintenance of BBB structure, function, or gene expression in the healthy brain. However, we found that PLX5622 treatment alters brain endothelial cholesterol metabolism, and this effect was independent from microglial depletion, suggesting PLX5622 has off-target effects on brain vasculature. Overall design: To determine whether PLX5622 alters cholesterol metabolism in astrocytes (the main cholesterol-producing cells in the adult brain), we put GFAP-Cre; RiboTag mice on PLX5622 diet or control diet for one month. We then attempted to isolate astrocytes using RiboTag methods. Ultimately, the sequenced population also included some neurons and oligodendrocytes, the other two cell types in the brain that produce cholesterol. Thus, we were able to assess whether PLX5622 alters cholesterol metabolism across multiple neuroglial cell types. Less...