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Proc Natl Acad Sci U S A. 2017 Nov 21;114(47):E10161-E10168. doi: 10.1073/pnas.1710680114. Epub 2017 Nov 6.

Blocking immunosuppression by human Tregs in vivo with antibodies targeting integrin αVβ8.

Author information

1
de Duve Institute, Université catholique de Louvain, B-1200 Brussels, Belgium.
2
Ludwig Institute for Cancer Research, Brussels branch, B-1200 Brussels, Belgium.
3
Department of Pathology, University of California, San Francisco, CA 94110.
4
Department of Medicine, University of California, San Francisco, CA 94143.
5
de Duve Institute, Université catholique de Louvain, B-1200 Brussels, Belgium; sophie.lucas@uclouvain.be.

Abstract

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.

KEYWORDS:

GARP (LRRC32); TGF-β; cancer immunotherapy; human regulatory T cells; integrin αVβ8

PMID:
29109269
PMCID:
PMC5703296
DOI:
10.1073/pnas.1710680114
[Indexed for MEDLINE]
Free PMC Article

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