Characterization of meningeal type 2 innate lymphocytes and their response to CNS injury.

The meningeal space is occupied by a diverse repertoire of immune cells. Central nervous system (CNS) injury elicits a rapid immune response that affects neuronal survival and recovery, but the role of meningeal inflammation remains poorly understood. Here, we describe type 2 innate lymphocytes (ILC2s) as a novel cell type resident in the healthy meninges that are activated after CNS injury. ILC2s are present throughout the naive mouse meninges, though are concentrated around the dural sinuses, and have a unique transcriptional profile. After spinal cord injury (SCI), meningeal ILC2s are activated in an IL-33-dependent manner, producing type 2 cytokines. Using RNAseq, we characterized the gene programs that underlie the ILC2 activation state. Finally, addition of wild-type lung-derived ILC2s into the meningeal space of IL-33R-/- animals partially improves recovery after SCI. These data characterize ILC2s as a novel meningeal cell type that responds to SCI and could lead to new therapeutic insights for neuroinflammatory conditions.