IDO1 suppresses inhibitor development in hemophilia A treated with factor VIII
Davide Matino, Marco Gargaro, Elena Santagostino, Matteo N.D. Di Minno, Giancarlo Castaman, Massimo Morfini, Angiola Rocino, Maria E. Mancuso, Giovanni Di Minno, Antonio Coppola, Vincenzo N. Talesa, Claudia Volpi, Carmine Vacca, Ciriana Orabona, Rossana Iannitti, Maria G. Mazzucconi, Cristina Santoro, Antonella Tosti, Sara Chiappalupi, Guglielmo Sorci, Giuseppe Tagariello, Donata Belvini, Paolo Radossi, Raffaele Landolfi, Dietmar Fuchs, Louis Boon, Matteo Pirro, Emanuela Marchesini, Ursula Grohmann, Paolo Puccetti, Alfonso Iorio, Francesca Fallarino
Davide Matino, Marco Gargaro, Elena Santagostino, Matteo N.D. Di Minno, Giancarlo Castaman, Massimo Morfini, Angiola Rocino, Maria E. Mancuso, Giovanni Di Minno, Antonio Coppola, Vincenzo N. Talesa, Claudia Volpi, Carmine Vacca, Ciriana Orabona, Rossana Iannitti, Maria G. Mazzucconi, Cristina Santoro, Antonella Tosti, Sara Chiappalupi, Guglielmo Sorci, Giuseppe Tagariello, Donata Belvini, Paolo Radossi, Raffaele Landolfi, Dietmar Fuchs, Louis Boon, Matteo Pirro, Emanuela Marchesini, Ursula Grohmann, Paolo Puccetti, Alfonso Iorio, Francesca Fallarino
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Research Article Hematology

IDO1 suppresses inhibitor development in hemophilia A treated with factor VIII

Abstract

The development of inhibitory antibodies to factor VIII (FVIII) is a major obstacle in using this clotting factor to treat individuals with hemophilia A. Patients with a congenital absence of FVIII do not develop central tolerance to FVIII, and therefore, any control of their FVIII-reactive lymphocytes relies upon peripheral tolerance mechanisms. Indoleamine 2,3-dioxygenase 1 (IDO1) is a key regulatory enzyme that supports Treg function and peripheral tolerance in adult life. Here, we investigated the association between IDO1 competence and inhibitor status by evaluating hemophilia A patients harboring F8-null mutations that were either inhibitor negative (n = 50) or positive (n = 50). We analyzed IDO1 induction, expression, and function for any relationship with inhibitor occurrence by multivariable logistic regression and determined that defective TLR9-mediated activation of IDO1 induction is associated with an inhibitor-positive status. Evaluation of experimental hemophilic mouse models with or without functional IDO1 revealed that tryptophan metabolites, which result from IDO1 activity, prevent generation of anti-FVIII antibodies. Moreover, treatment of hemophilic animals with a TLR9 agonist suppressed FVIII-specific B cells by a mechanism that involves IDO1-dependent induction of Tregs. Together, these findings indicate that strategies aimed at improving IDO1 function should be further explored for preventing or eradicating inhibitors to therapeutically administered FVIII protein.

Authors

Davide Matino, Marco Gargaro, Elena Santagostino, Matteo N.D. Di Minno, Giancarlo Castaman, Massimo Morfini, Angiola Rocino, Maria E. Mancuso, Giovanni Di Minno, Antonio Coppola, Vincenzo N. Talesa, Claudia Volpi, Carmine Vacca, Ciriana Orabona, Rossana Iannitti, Maria G. Mazzucconi, Cristina Santoro, Antonella Tosti, Sara Chiappalupi, Guglielmo Sorci, Giuseppe Tagariello, Donata Belvini, Paolo Radossi, Raffaele Landolfi, Dietmar Fuchs, Louis Boon, Matteo Pirro, Emanuela Marchesini, Ursula Grohmann, Paolo Puccetti, Alfonso Iorio, Francesca Fallarino

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Figure 7

CpGH DC treatment from inhibitor-negative patients promotes Treg responses.

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CpGH DC treatment from inhibitor-negative patients promotes Treg respons...
(A) ELISA measurements of the relative amounts (A450) of p65 and p52 in DCs from inhibitor-negative and inhibitor-positive patients treated with CpG-ODN (3 μg/ml) at different times. Data represent mean ± SD of 3 independent experiments. *P < 0.05, Dunnett test (treatment vs. time 0). IDO1 transcripts (B) and l-kynurenine production (C) in FL-DCs from inhibitor-positive and inhibitor-negative patients, either untreated or treated with CpG-ODN (3 μg/ml); n = 5. IDO1 mRNA is presented relative to expression in the respective, freshly isolated DCs (in which fold change = 1; dotted line). Data represent mean ± SD of 3 experiments. **P < 0.01; ***P < 0.001, Student’s t test. (D) Representative results of CD4+FOXP3+ cell frequency (top right quadrants) among CD4+ T cells, cultured for 5 days with DCs, either untreated or CpG treated, with or without rhFVIII. Representative results from 1 experiment of 5. (E) CD4+FOXP3+ cell frequency in cultures established as in D; n = 5. Mean ± SD (3 independent experiments). (F) Cytokine analysis in cells treated as in D on day 4. *P < 0.05; **P < 0.01, Student’s t test.