Blocking immunosuppression by human Tregs in vivo with antibodies targeting integrin aVß8

• Published in: Proceedings of the National Academy of Sciences - PNAS 2017-11, Vol.114 (47), p.E10161
• Main Authors: Stockis, Julie, Liénart, Stéphanie, Colau, Didier, Collignon, Amandine, Nishimura, Stephen L, Sheppard, Dean, Coulie, Pierre G, Lucas, Sophie
• Format: Article
• Language: English
• Subjects: Antibodies; Blocking; Blocking antibodies; Cancer; Cancer therapies; Cell activation; Dimers; Graft-versus-host reaction; Immunodeficiency; Immunoglobulins; Immunoregulation; Immunosuppression; Immunotherapy; Integrins; Lymphocytes; Lymphocytes T; T cell receptors; Transforming growth factor-b1; Xenografts
• ISSN: 0027-8424; 1091-6490

Human regulatory T cells (Tregs) suppress other T cells by converting the latent, inactive form of TGF-β1 into active TGF-β1. In Tregs, TGF-β1 activation requires GARP, a transmembrane protein that binds and presents latent TGF-β1 on the surface of Tregs stimulated through their T cell receptor. However, GARP is not sufficient because transduction of GARP in non-Treg T cells does not induce active TGF-β1 production. RGD-binding integrins were shown to activate TGF-β1 in several non-T cell types. Here we show that αVβ8 dimers are present on stimulated human Tregs but not in other T cells, and that antibodies against αV or β8 subunits block TGF-β1 activation in vitro. We also show that αV and β8 interact with GARP/latent TGF-β1 complexes in human Tregs. Finally, a blocking antibody against β8 inhibited immunosuppression by human Tregs in a model of xenogeneic graft-vs.-host disease induced by the transfer of human T cells in immunodeficient mice. These results show that TGF-β1 activation on the surface of human Tregs implies an interaction between the integrin αVβ8 and GARP/latent TGF-β1 complexes. Immunosuppression by human Tregs can be inhibited by antibodies against GARP or against the integrin β8 subunit. Such antibodies may prove beneficial against cancer or chronic infections.