Frontiers in Immunology (Apr 2021)

BTLA Expression and Function Are Impaired on SLE B Cells

  • Annika Wiedemann,
  • Annika Wiedemann,
  • Marie Lettau,
  • Marie Lettau,
  • Sarah Y. Weißenberg,
  • Sarah Y. Weißenberg,
  • Ana-Luisa Stefanski,
  • Ana-Luisa Stefanski,
  • Eva-Vanessa Schrezenmeier,
  • Eva-Vanessa Schrezenmeier,
  • Eva-Vanessa Schrezenmeier,
  • Hector Rincon-Arevalo,
  • Hector Rincon-Arevalo,
  • Hector Rincon-Arevalo,
  • Hector Rincon-Arevalo,
  • Karin Reiter,
  • Karin Reiter,
  • Tobias Alexander,
  • Tobias Alexander,
  • Falk Hiepe,
  • Falk Hiepe,
  • Andreia C. Lino,
  • Andreia C. Lino,
  • Thomas Dörner,
  • Thomas Dörner

DOI
https://doi.org/10.3389/fimmu.2021.667991
Journal volume & issue
Vol. 12

Abstract

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B- and T-lymphocyte attenuator (BTLA/CD272) is an inhibitory checkpoint molecule expressed on T and B cells. Prior studies reported defective function of BTLA by T cells in patients with systemic lupus erythematosus (SLE), whereas nothing is known about its role on B cells in SLE, a disease with various B cell abnormalities. Peripheral blood mononuclear cells (PBMCs) from 23 healthy donors (HD) and 34 SLE patients were stained for BTLA and its expression on B cells was assessed. PBMCs or CD27-IgD+ naive B cells were stimulated together with an activating anti-BTLA antibody or an inhibitor of spleen tyrosine kinase (SYK) and differentiation as well as the expression of activation markers CD71, PD-1 and CD86 were analyzed. Our phenotypic and functional studies revealed reduced BTLA expression on CD27-IgD+ naïve B cells from SLE patients (p=0.0017) related to anti-dsDNA antibody titers (p=0.0394) and SIGLEC-1/CD169 expression on monocytes (p=0.0196), a type I interferon marker related to disease activity. BTLA engagement was found to control CpG/TLR9 activation limiting plasmablast (p=0.0156) and B cell memory induction (p=0.0078) in normal B cells in contrast to other B cell activation pathways (CD40, BCR). These BTLA functions were impaired in SLE B cells. Inhibition of SYK was found to mimic the effects of BTLA activity in vitro. Thus, is it possible that reduced BTLA expression and function of CD27-IgD+ antigen- and T cell-inexperienced SLE B cells could be overcome by SYK inhibition which should be tested in future studies as potential therapeutic principle.

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