Heterogeneity and developmental dynamics of LYVE-1 perivascular macrophages distribution in the mouse brain

Brain perivascular macrophages (PVMs) belong to border-associated macrophages. PVMs are situated along blood vessels in the Virchow-Robin space and are thus found at a unique anatomical position between the endothelium and the parenchyma. Owing to their location and phagocytic capabilities, PVMs are regarded as important components that regulate various aspects of brain physiology in health and pathophysiological states. Here, used LYVE-1 to identify PVMs in the mouse brain. We used brain-tissue sections and cleared whole-brains to learn how they are distributed within the brain and across different developmental postnatal stages. We find that LYVE-1+ PVMs associate with the vasculature in a brain-region-dependent manner, where the hippocampus shows the highest density of LYVE-1+ PVMs. We show that their postnatal distribution is developmentally dynamic and peaks at P10-P20 depending on the brain region. We further demonstrate that their density is reduced in the APP/PS1 mouse model of Alzheimers Disease. In conclusion, our results show an unexpected heterogeneity and dynamics of LYVE-1+ PVMs, and support an important role for this population of PVMs during development and in regulating brain functions in steady-state and disease conditions.