Immunomodulation for inhibitors in hemophilia A: the important role of Treg cells

Abstract

Approximately 25–30% of the hemophilia A patients develop inhibitory antibodies against Factor VIII (FVIII) following protein-replacement therapy. This problem is also thought to occur following gene-replacement therapy. Recently, many approaches have been investigated to modulate FVIII-specific immune responses in either protein-replacement or gene therapy hemophilia A mouse models. Several promising protocols have been demonstrated to successfully prevent or modulate the formation of anti-FVIII antibodies, including methods to manipulate antigen presentation, development of less immunogenic FVIII proteins, or formulations or gene therapy protocols to evade immune responses, as well as immunomodulation strategies to target either T- and/or B-cell responses. Most of these successful protocols involve the induction of activated Treg cells to create a regulatory immune environment during tolerance induction. Innovative strategies to overcome pre-existing anti-FVIII immune responses and induce long-term tolerance in primed subjects still need to be developed.

Keywords::

• antibody
• Factor VIII
• gene therapy
• hemophilia
• immunomodulation
• immunosuppressive regimen
• inhibitor
• protein-replacement therapy
• tolerance induction
• Treg

Financial & competing interests disclosure

Carol Miao is supported by the grants from NIH/NHLBI (R01 HL082600, R01 HL069049 and R21/R33 HL089038) and a special project grant from the Bayer Hemophilia Foundation. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.