Immunity https://doi.org/10.1016/j.immuni.2018.12.012 (2018)

In the central nervous system, the cytokine IL-1 controls sleep regulation, memory consolidation, neurodegeneration and sickness behavior. In Immunity, Quan and colleagues use a mouse model that allows the in vivo visualization of cells that express mRNA encoding the IL-1 receptor IL-1R1 (Il1r1) and the cell-type-specific re-expression of endogenous IL-1R1 to investigate the effect of IL-1 in the brain. Under physiological conditions, Il1r1 is expressed in endothelial cells, dentate gyrus neurons and choroid plexus cells and at very low levels in astrocytes but not in microglia or macrophages. After intra-cerebroventricular injection of IL-1β, endothelial IL-1R (eIL-1R1) mediates sickness behavior; eIL-1-R1 and myeloid IL-1R1 inhibit neurogenesis; and ventricular (choroid plexus) IL-1R1 (vIL-1R1) recruits monocytes. vIL-1R1 and eIL-1R1 mediate the infiltration of neutrophils via the ventricular route and vascular route, respectively, and induce activation of microglia, while eIL-1R1 induces the production of inflammatory mediators in microglia.