Probes for CCR1

Microglia are specialized macrophages in the brain parenchyma that exist in multiple transcriptional states and reside within a wide range of neuronal environments1-4. However, how and where these states are generated remains poorly understood. Here, using the mouse somatosensory cortex, we demonstrate that microglia density and molecular state acquisition are determined by the local composition of pyramidal neuron classes. Using single-cell and spatial transcriptomic profiling, we unveil the molecular signatures and spatial distributions of diverse microglia populations and show that certain states are enriched in specific cortical layers, whereas others are broadly distributed throughout the cortex. Notably, conversion of deep-layer pyramidal neurons to an alternate class identity reconfigures the distribution of local, layer-enriched homeostatic microglia to match the new neuronal niche. Leveraging the transcriptional diversity of pyramidal neurons in the neocortex, we construct a ligand-receptor atlas describing interactions between individual pyramidal neuron subtypes and microglia states, revealing rules of neuron-microglia communication. Our findings uncover a fundamental role for neuronal diversity in instructing the acquisition of microglia states as a potential mechanism for fine-tuning neuroimmune interactions within the cortical local circuitry.

Chronic infusion of Ang II caused increased of leukocyte (CD45+) content in PVAT in both WT and ACKR2-/- mice. This increase was particularly evident for T cell subsets in WT but not in ACKR2-/-. However the number of macrophages (F4/80+CD11b+) was increased in both groups. Interestingly, ACKR2-/- revealed decreased T cell number infiltrating PVAT upon Ang II infusion in comparison to WT. Hypertension was associated with increased CCR1, CCR2 and CCR3 expression in PVAT in both WT and ACKR2-/-. However, ACKR2-/- revealed higher expression of CCR1 and CCR2 but not CCR3 in comparison to WT. Interestingly, increased expression of CCR5 in PVAT upon Ang II infusion in WT was not observed in ACKR2-/-. Hypertension resulted in increased RANTES level in aorta and PVAT to the same extent in both WT and ACKR2-/-. However, MCP-1, MIP-1 alpha and MIP-1 beta level was higher in ACKR2-/- aorta than in WT aorta upon Ang II infusion. ACKR2 expression was lower in PVAT than in aorta. Interestingly, Ang II administration decreased the expression of ACKR2 in aorta but increased ACKR2 level in thoracic PVAT. RNAscope analysis revealed ACKR2 expression in vascular smooth muscle cells (VSMC). Vessels isolated from ACKR2-/- were protected from vascular dysfunction and revealed reduced ROS production in comparison to WT upon Ang II administration. ACKR2-/- mice developed similar extent of blood pressure increase as WT in hypertension.