OX40L/OX40 axis impairs follicular and natural Treg function in human SLE
Clément Jacquemin, Jean-François Augusto, Marc Scherlinger, Noémie Gensous, Edouard Forcade, Isabelle Douchet, Emeline Levionnois, Christophe Richez, Estibaliz Lazaro, Pierre Duffau, Marie-Elise Truchetet, Julien Seneschal, Lionel Couzi, Jean-Luc Pellegrin, Jean-François Viallard, Thierry Schaeverbeke, Virginia Pascual, Cécile Contin-Bordes, Patrick Blanco
Clément Jacquemin, Jean-François Augusto, Marc Scherlinger, Noémie Gensous, Edouard Forcade, Isabelle Douchet, Emeline Levionnois, Christophe Richez, Estibaliz Lazaro, Pierre Duffau, Marie-Elise Truchetet, Julien Seneschal, Lionel Couzi, Jean-Luc Pellegrin, Jean-François Viallard, Thierry Schaeverbeke, Virginia Pascual, Cécile Contin-Bordes, Patrick Blanco
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Research Article Immunology

OX40L/OX40 axis impairs follicular and natural Treg function in human SLE

Abstract

Tregs are impaired in human systemic lupus erythematosus (SLE) and contribute to effector T cell activation. However, the mechanisms responsible for the Treg deficiency in SLE remain unclear. We hypothesized that the OX40L/OX40 axis is implicated in Treg and regulatory follicular helper T (Tfr) cell dysfunction in human SLE. OX40L/OX40 axis engagement on Tregs and Tfr cells not only specifically impaired their ability to regulate effector T cell proliferation, but also their ability to suppress T follicular helper (Tfh) cell–dependent B cell activation and immunoglobulin secretion. Antigen-presenting cells from patients with active SLE mediated Treg dysfunction in an OX40L-dependent manner, and OX40L-expressing cells colocalized with Foxp3+ cells in active SLE skin lesions. Engagement of the OX40L/OX40 axis resulted in Foxp3 downregulation in Tregs, and expression in SLE Tregs correlated with the proportion of circulating OX40L-expressing myeloid DCs. These data support that OX40L/OX40 signals are implicated in Treg dysfunction in human SLE. Thus, blocking the OX40L/OX40 axis appears to be a promising therapeutic strategy.

Authors

Clément Jacquemin, Jean-François Augusto, Marc Scherlinger, Noémie Gensous, Edouard Forcade, Isabelle Douchet, Emeline Levionnois, Christophe Richez, Estibaliz Lazaro, Pierre Duffau, Marie-Elise Truchetet, Julien Seneschal, Lionel Couzi, Jean-Luc Pellegrin, Jean-François Viallard, Thierry Schaeverbeke, Virginia Pascual, Cécile Contin-Bordes, Patrick Blanco

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Figure 1

OX40L impairs the suppressive function of Tregs.

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OX40L impairs the suppressive function of Tregs. (A and B) Sorted effect...
(A and B) Sorted effector T4 (Eff.T4) cells (104 cells) were labeled with CFSE (5 μM), activated (anti-CD3, 1 μg/ml and anti-CD28, 3 μg/ml) or not for unstimulated condition, and cultured for 3 days alone or with sorted Tregs (104 cells) in the presence or absence of soluble OX40L (sOX40L) (100 ng/ml). Eff.T4 cell proliferation was assessed after 3 days of culture. (A) Representative dot plot showing proliferation (CFSEdim) of Eff.T4 cells after 3 days of culture. (B) Percentage of inhibition of Eff.T4 cell proliferation. The percentage of inhibition was calculated in reference to proliferation observed with stimulated Eff.T4 cells cultured alone. Error bars indicate the mean ± SEM, n = 4 independent experiments. Statistical analysis was undertaken using the Mann-Whitney U test. *P < 0.05. (C–F) GM-CSF+IL-4 DCs or SLE DCs were cultured with purified Eff.T4 cells and Tregs for 3 days. Analysis of Eff.T4 cell proliferation was performed by (3H) thymidine incorporation measurement. (C) Analysis of Treg-suppressive function toward Eff.T4 cell proliferation at 3 different ratios of GM+IL-4 DCs or SLC DCs with Eff.T4 cells or Tregs (0.03:1:1, 0.1:1:1 and 0.3:1:1) of 3 independent experiments. (D) Analysis of Treg-suppressive function toward Eff.T4 cell proliferation at 4 different Treg/Eff.T4 cell ratios (0:1, 0.5:1, 1:1, and 2:1) of 3 independent experiments. (E) Representative experiment performed in triplicate showing that DCs, Tregs, and Eff.T4 cells were cocultured at a 0.1:1:1 ratio, respectively. Anti-OX40L blocking mAb restores Treg-suppressive function. (F) Cumulative data obtained with 6 GM-CSF+IL-4 DCs and 10 SLE DCs. GM-CSF+IL-4 DCs or SLE DCs, Eff.T4 cells, and Tregs were cultured at 0.1:1:1 ratio, respectively. Treg-suppressive function was defined as the percentage of Eff.T4 cell proliferation inhibition and calculated as follows: (Eff.T4 + Treg)condition cpm/(Eff.T4)condition cpm) × 100. Statistical analysis was done using the Kruskal-Wallis test followed by Dunn’s multiple comparison correction. *P < 0.05, **P < 0.002.