Immune tolerance against infused FVIII in hemophilia A is mediated by PD-L1+ Tregs
Janine Becker-Gotot, … , Johannes Oldenburg, Christian Kurts
Janine Becker-Gotot, … , Johannes Oldenburg, Christian Kurts
Published September 15, 2022
Citation Information: J Clin Invest. 2022;132(22):e159925. https://doi.org/10.1172/JCI159925.
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Research Article Hematology Immunology

Immune tolerance against infused FVIII in hemophilia A is mediated by PD-L1+ Tregs

Abstract

A major complication of hemophilia A therapy is the development of alloantibodies (inhibitors) that neutralize intravenously administered coagulation factor VIII (FVIII). Immune tolerance induction therapy (ITI) by repetitive FVIII injection can eradicate inhibitors, and thereby reduce morbidity and treatment costs. However, ITI success is difficult to predict and the underlying immunological mechanisms are unknown. Here, we demonstrated that immune tolerance against FVIII under nonhemophilic conditions was maintained by programmed death (PD) ligand 1–expressing (PD-L1–expressing) regulatory T cells (Tregs) that ligated PD-1 on FVIII-specific B cells, causing them to undergo apoptosis. FVIII-deficient mice injected with FVIII lacked such Tregs and developed inhibitors. Using an ITI mouse model, we found that repetitive FVIII injection induced FVIII-specific PD-L1+ Tregs and reengaged removal of inhibitor-forming B cells. We also demonstrated the existence of FVIII-specific Tregs in humans and showed that such Tregs upregulated PD-L1 in patients with hemophilia after successful ITI. Simultaneously, FVIII-specific B cells upregulated PD-1 and became killable by Tregs. In summary, we showed that PD-1–mediated B cell tolerance against FVIII operated in healthy individuals and in patients with hemophilia A without inhibitors, and that ITI reengaged this mechanism. These findings may impact monitoring of ITI success and treatment of patients with hemophilia A.

Authors

Janine Becker-Gotot, Mirjam Meissner, Vadim Kotov, Blanca Jurado-Mestre, Andrea Maione, Andreas Pannek, Thilo Albert, Chrystel Flores, Frank A. Schildberg, Paul A. Gleeson, Birgit M. Reipert, Johannes Oldenburg, Christian Kurts

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Figure 8

PD-1 stimulation induces apoptosis in human FVIII- and FIX-specific B cells.

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PD-1 stimulation induces apoptosis in human FVIII- and FIX-specific B ce...
(A) MFI of PD-1 expression by FVIII- and FIX-specific and nonspecific B cells from 9 healthy donors detected by flow cytometry. *P < 0.05 by 1-way ANOVA with Dunn’s post hoc test. NS, not significant. (B) Example of PD-1 expression by FVIII-specific B cells from 1 representative donor. (C–F) Percentage of apoptotic FVIII-specific (C), FIX-specific (D), non–FVIII-specific (E), and GFP-specific (F) B cells without and after incubation with a PD-L1 chimeric protein that specifically stimulates PD-1 in vitro. (G) The presence of FVIII-specific CD4+ T cells was analyzed in blood samples of an HLA-matched patient sample (n = 3) who had undergone successful ITI. (H) The percentage of CD25+CD127– (Tregs) of HLA-matched tetramer+CD4+ cells is depicted as a representative example. (I) The geometric MFI of PD-L1 was analyzed on FVIII-specific CD4+ HLA-matched Tregs versus nonspecific Tregs from the same patient blood sample. *P < 0.05 by 1-way ANOVA with Dunn’s post hoc test (A) or paired, 2-tailed Student’s t test (C–F and I). NS, not significant.