Cutting edge: Regulatory T cells directly suppress B cells in systemic lupus erythematosus - PubMed (original) (raw)

Cutting edge: Regulatory T cells directly suppress B cells in systemic lupus erythematosus

Noriko Iikuni et al. J Immunol. 2009.

Abstract

In systemic lupus erythematosus (SLE), adaptive CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) suppress Th cells that help autoantibody (autoAb)-producing B cells. It is not known whether naturally occurring Tregs can directly suppress B cells in SLE without an intermediate suppression of Th cells. This aspect is important for its implications in the natural course of SLE, because most if not all of the clinical and pathologic effects in SLE are associated with a dysregulated production of autoAbs. In this study, we show that natural Tregs can inhibit B cell activity in vitro and in vivo in SLE through cell contact-mediated mechanisms that directly suppress autoAb-producing B cells, including those B cells that increase numerically during active disease. These results indicate that one way by which natural Tregs attempt to limit humoral autoimmunity in SLE is by directly targeting autoreactive B cells.

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Conflict of interest statement

Disclosures

The authors have no financial conflict of interest.

Figures

FIGURE 1

Natural Tregs directly suppress lupus B cells in vitro. B cells (1 × 106) from old NZB/W mice were not stimulated or stimulated with LPS or anti-CD40 mAb and cocultured for 12 h with Tregs at a 1:10 ratio before ELISA assessment of Ab production in the supernatant. a, Production of IgG by anti-CD40 (aCD40)-stimulated B cells is inhibited by natural Tregs and not by CD4+CD25− Th cells; *, p < 0.005; **, _p_ < 0.04. _b_, Age does not affect the ability of Tregs to suppress B cells. ELISA for IgG content in the supernatant from cocultures of B cells with Tregs from young (10–12 wk old) or old (> 30 wk old) NZB/W mice was performed; *, p < 0.003; **, p < 0.04; ***, p < 0.01; ****, p < 0.03. c and d, Natural Tregs directly suppress anti-DNA autoAb production from old NZB/W lupus mice B cells after 16 h of coculture. c, Tregs of young NZB/W mice directly suppress production of anti-DNA Ab in unstimulated and stimulated B cells; *, p < 0.0001; **, p < 0.002; ***, p < 0.007. Similar results were obtained with Tregs from old mice (data not shown). d, Tregs from young or old mice suppress anti-DNA Ab production in both unstimulated and stimulated B cells from old mice; *, p < 0.01; **, p < 0.04.

FIGURE 2

Tregs induce apoptosis of B cells in SLE. B cells from old mice were cultured for 16 h in the presence or absence (as control) of syngeneic Tregs at 1:10 ratio before flow cytometry analysis for apoptosis in gated (CD19+) B cells. a, Tregs need cell-to-cell contact to suppress B cells. Tregs from NZB/W mice were cocultured with syngeneic B cells or in transwell inserts with 0.4-µm pores. Shown are flow cytometry data on gated B cells vs B cells alone. *, p < 0.006; **, p < 0.002. b, Apoptosis of B cells cultured in the presence of Tregs from young and old mice is dose dependent. B cells (1 × 105 per well) were cultured alone or in the presence of Tregs and staining for annexin V and 7-AAD was assessed by flow cytometry on gated B cells. *, p < 0.0001; **, p < 0.01; ***, p < 0.007; ****, p < 0.001. c, Perforins and granzymes are required for the suppressive activity of Tregs on B cells. Shown is B cell death in cocultures with Tregs in the absence (medium) or the presence of EGTA, anti-perforin (α-perf), and anti-granzyme (α-granz) mAbs *, p < 0.09; **, p < 0.001; ***, p < 0.003; ****, p < 0.0004.

FIGURE 3

Human Tregs directly suppress B cells in SLE. a and b, Tregs were cultured alone or together with autologous B cells (1:1) stimulated with anti-CD40 Ig, IL-4 and IL-10 for 16 h. a, B cell production of IgG by ELISA; *, p < 0.01; not significant between B cells vs B plus Tregs from controls. b, B cell death assessed by flow cytometry in the presence of Tregs; *, p < 0.001; **, p < 0.01; not significant between B only vs B plus Tregs in controls and B only from SLE vs controls. c, Cell death of untreated or anti-CD40Ig/IL-4/IL-10-stimulated (st) CD19+CD27high and CD19+CD27−IgD− B cells in the presence or absence of autologous Tregs. Data are mean ± SD from separate experiments in nine SLE patients. *, p < 0.04; **, p < 0.0007; ***, p < 0.009.

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Cutting edge: Regulatory T cells directly suppress B cells in systemic lupus erythematosus - PubMed (original) (raw)