Phosphatidylserine Outer Layer Translocation Is Implicated in IL-10 Secretion by Human Regulatory B Cells

PLoS One. 2017 Jan 10;12(1):e0169755. doi: 10.1371/journal.pone.0169755. eCollection 2017.

Abstract

B cells can have a regulatory role, mainly mediated by interleukin 10 (IL-10). IL-10 producing B cells (B10 cells) cells remain to be better characterized. Annexin V binds phosphatidylserine (PS), which is externalized during apoptosis. Previous works suggested that B10 cells are apoptotic cells since they bind Annexin V. Others showed that Annexin V binding could also be expressed on viable B cells. We aimed to explore if PS exposure can be a marker of B10 cells and if PS exposure has a functional role on B cell IL-10 production in healthy subjects. We found that B10 cells were significantly more often Annexin V+ than IL-10 non-producing B cells. After CpG activation, Annexin V+ B cells differentiated more often into B10 cells than Annexin Vneg B cells. Cell death and early apoptosis were similar between Annexin V+ and Annexin Vneg B cells. PS blockage, using biotinylated AnV and glyburide, decreased B10 cell differentiation. This study showed that B10 cells have an increased PS exposure independently of any apoptotic state. B cells exposing PS differentiate more into B10 cells whereas PS blockage inhibits B10 cells generation. These results strongly suggest a link between PS exposure and B10 cells.

MeSH terms

  • Apoptosis
  • B-Lymphocytes, Regulatory / metabolism*
  • Cell Membrane / metabolism*
  • Cells, Cultured
  • Humans
  • Interleukin-10 / metabolism*
  • Phosphatidylserines / metabolism*

Substances

  • Phosphatidylserines
  • Interleukin-10

Grants and funding

This work was funded by UCB Pharma France S.A. (SIRIUS grant) and also supported by the Centre Hospitalier Universitaire Montpellier (France). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.