Similar to mammals, zebrafish have multi-layered meninges and scRNA-seq profiling of the adult zebrafish meningeal layers, revealed multiple uncharacterized meningeal cell populations. We are extending on these findings to build a comprehensive descriptive “catalog” of the location, morphology, and molecular character of cell types residing in the adult zebrafish meningeal layers. We carry out detailed histological and Transmitted Electron Microscopy (TEM) characterization of the adult zebrafish meninges to pinpoint the location and ultrastructural morphology of specific meningeal cell populations. Additionally, to determine whether a zebrafish meningeal cell type has an analogous counterpart in mammals, we use scRNA-seq analysis to identify and validate known and especially novel cell clusters in the leptomeninges and dural mater, taking advantage of available mammalian and zebrafish transcriptomic datasets. Upon identification of selected cell cluster-specific markers we generate reporter transgenic lines for high-resolution confocal imaging of distinct populations in vivo, prioritizing promoters of genes expressed exclusively in novel uncharacterized cell clusters, especially if there is evidence implicating them in neuro-vascular development, waste removal, or neurodegeneration. 

Infection of the meninges causes meningitis, and the meningeal ability to remove CSF waste declines as we age, suggesting a potential age-dependent degeneration of meningeal scavenging abilities. Some meningeal cells express pathogen recognition receptors and are thought to protect the brain from potential meningitis-causing pathogens. To determine how meningeal cells control neuro-vascular health, we investigate the effects of infection and aging on meningeal cells in: (1) Control versus Meningitis-infected animals and/or (2) young vs. old animals. These studies will eventually be complemented by examining these effects in meningeal mutants isolated from genetic screens, via reverse-genetic targeting of candidate genes identified in by scRNA-seq profiling, or, potentially, in animals with ablated meningeal cell populations.