CNS antigen-specific control of early B-lineage development in the meninges

In this work we report that early developing B cells present in the meninges of mice at all ages. Single cell RNA-sequencing (scRNA-seq) analysis revealed a consecutive trajectory of meningeal developing B cells in mice and non-human primates (NHPs). Parabiosis together with lineage tracing of hematopoietic stem cells (HSCs) showed that meningeal developing B cells are continuously replenished from the HSC-derived progenitors via a circulation-independent route. Importantly, autoreactive immature B cells which recognize myelin oligodendrocyte glycoprotein (MOG), a central nervous system (CNS)-specific antigen, are eliminated from the meninges but not BM. Furthermore, genetic deletion of MOG tolerated the development/presence/residence of self-reactive B cells in the meninges. Thus, we propose that meninges function as a unique reservoir for B cell development, allowing in situ negative selection of CNS-antigen-autoreactive B cell clones to ensure a local non-self-reactive immune repertoire. Flow-sorted murine meningeal cells (CD45–CD11b–), which were pre-labeled with hashtag antibodies (Biolegend), were pooled and loaded at 30,000 cells per channel. Flow-sorted macaque immune cell population (CD45–CD11b–CD3–) were loaded at 8,000 cells per channel. The cells were then partitioned into the GemCode instrument, where individual cells were lysed and mixed with beads carrying unique barcodes in individual oil droplets. The products were subjected to reverse transcription, emulsion breaking, cDNA amplification, and sample index attachment. Libraries were pair-end (150+ 150 bp) sequenced on a NovaSeq (Illumina).