Antibody-secreting cell destiny emerges during the initial stages of B-cell activation

Abstract

Upon stimulation, B cells assume heterogeneous cell fates, with only a fraction differentiating into antibody-secreting cells (ASC). Here we investigate B cell fate programming and heterogeneity during ASC differentiation using T cell-independent models. We find that maximal ASC induction requires at least eight cell divisions in vivo, with BLIMP-1 being required for differentiation at division eight. Single cell RNA-sequencing of activated B cells and construction of differentiation trajectories reveal an early cell fate bifurcation. The ASC-destined branch requires induction of IRF4, MYC-target genes, and oxidative phosphorylation, with the loss of CD62L expression serving as a potential early marker of ASC fate commitment. Meanwhile, the non-ASC branch expresses an inflammatory signature, and maintains B cell fate programming. Finally, ASC can be further subseted based on their differential responses to ER-stress, indicating multiple development branch points. Our data thus define the cell division kinetics of B cell differentiation in vivo, and identify the molecular trajectories of B cell fate and ASC formation.

Roadmap to a plasma cell: Epigenetic and transcriptional cues that guide B cell differentiation

“…23 Consistent with other scRNA profiling of GC B cell populations, 113,114 we observed substantial heterogeneity within the activated, dividing B cell population. 23 One scRNA-seq analytical approach is to take advantage of the heterogeneity and small differences between cells to order cells along a response trajectory termed pseudotime. 115 This analysis is ideally suited to the data described above where GC-dependent memory, and long-lived ASC.…”

“…22 A follow-up study with finer temporal mapping showed the emergence of ASC occurred between 54 hours and 60 hours of stimulation and that only cells that had divided eight times and acquired CD138 surface expression secreted antibodies in ELISPOT assays. 23 Altering the dose of LPS only affected the number of responding B cells but not the requirement for eight divisions before ASCs were observed in this model. When B cells were transferred and stimulated with LPS in wildtype (WT) hosts, we observed a small number of CD138 + ASC forming as early as division 5.…”

“…Therefore, like the gene expression programs they control, transcription factors are dynamically expressed and exhibit stage-specific activity during differentiation.To begin to understand how gene expression programs developed in tandem with cell division during in vivo B cell differentiation, we isolated B cells after adoptive transfer and LPS stimulation from divisions 0, 1, 3, 5, and 8 that were either CD138-or CD138+. RNAseq was performed using synthetic ERCC spike-in controls53 that allowed precise measurement of gene expression in the form of mRNA copies per cell 21,23. This revealed a global amplification of gene expression that was progressive through the divisions and peaked with ~6-fold more total mRNA in division 8 CD138 + cells.…”

What Will B Will B: Identifying Molecular Determinants of Diverse B-Cell Fate Decisions Through Systems Biology

“…Recent single-cell RNAseq data indicate a bifurcation during the early stages of B-cell activation, committing a portion of cells to an ASC destiny ( Scharer et al, 2020 ). This requires Interferon Regulatory Factor 4 (IRF4) induction, with higher and sustained activation biasing cells toward ASC fates ( Ochiai et al, 2013 ).…”

Role of Polycomb Complexes in Normal and Malignant Plasma Cells

“…Therefore, it has been suggested that in the absence of EZH2, ASC cannot proliferate due to their inability to suppress cell cycle inhibitors [44]. The phenotype and transcriptome of ASC produced at each mitosis were studied using an in vivo cell tracking model [47,48]. This analysis showed that in the absence of EZH2, the first three divisions after activation are normal, but most ASC become unable to continue to proliferate up to eight divisions.…”