T cell receptor–targeted immunotherapeutics drive selective in vivo HIV- and CMV-specific T cell expansion in humanized mice
Mengyan Li, … , Steven C. Almo, Harris Goldstein
Mengyan Li, … , Steven C. Almo, Harris Goldstein
Published October 21, 2021
Citation Information: J Clin Invest. 2021;131(23):e141051. https://doi.org/10.1172/JCI141051.
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Research Article AIDS/HIV Immunology

T cell receptor–targeted immunotherapeutics drive selective in vivo HIV- and CMV-specific T cell expansion in humanized mice

Abstract

To delineate the in vivo role of different costimulatory signals in activating and expanding highly functional virus-specific cytotoxic CD8+ T cells, we designed synTacs, infusible biologics that recapitulate antigen-specific T cell activation signals delivered by antigen-presenting cells. We constructed synTacs consisting of dimeric Fc-domain scaffolds linking CD28- or 4-1BB–specific ligands to HLA-A2 MHC molecules covalently tethered to HIV- or CMV-derived peptides. Treatment of HIV-infected donor PBMCs with synTacs bearing HIV- or CMV-derived peptides induced vigorous and selective ex vivo expansion of highly functional HIV- and/or CMV-specific CD8+ T cells, respectively, with potent antiviral activities. Intravenous injection of HIV- or CMV-specific synTacs into immunodeficient mice intrasplenically engrafted with donor PBMCs markedly and selectively expanded HIV-specific (32-fold) or CMV-specific (46-fold) human CD8+ T cells populating their spleens. Notably, these expanded HIV- or CMV-specific CD8+ T cells directed potent in vivo suppression of HIV or CMV infections in the humanized mice, providing strong rationale for consideration of synTac-based approaches as a therapeutic strategy to cure HIV and treat CMV and other viral infections. The synTac platform flexibility supports facile delineation of in vivo effects of different costimulatory signals on patient-derived virus-specific CD8+ T cells, enabling optimization of individualized therapies, including HIV cure strategies.

Authors

Mengyan Li, Scott J. Garforth, Kaitlyn E. O’Connor, Hang Su, Danica M. Lee, Alev Celikgil, Rodolfo J. Chaparro, Ronald D. Seidel, R. Brad Jones, Ravit Arav-Boger, Steven C. Almo, Harris Goldstein

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Figure 1

Structural representation of synTac proteins and their production and functional activity.

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Structural representation of synTac proteins and their production and fu...
(A) SynTacs were constructed as a split sc-pMHC-Fc fusion, with the β2M and the MHC HLA-A*0201 alpha chain linked through engineered interchain disulfide bonds, and the FLAG, αCD28, or 4-1-BBL domains linked to the β2M carboxy end. (B) Outline of protocol for production of SL9- or pp65-FLAG, -αCD28, and -4-1BBL synTacs. (C) SDS-PAGE gel showing the molecular weights of the reduced synTacs. (D) 4-1BB expression on Jurkat/MA cells that were transduced with a 4-1BB–encoding lentiviral vector. (E) Quantification of synTac (1 nM) bound to 4-1BB–expressing Jurkat/MA cells. (F) 4-1BB–expressing Jurkat/MA cells that express an NFAT-driven luciferase reporter were incubated with synTac constructs (100 nM) or stimulated with PMA/ionomycin. After overnight incubation, luciferase activity was measured. (G) Jurkat/MA cells were transduced with a lentivector encoding a TCR specific for either SL9 (left) or KK10 (right), incubated with the indicated synTac molecules (1.56 nM) for 30 minutes, and bound synTac molecules were detected by flow cytometry. (H) Luciferase activity was quantified after overnight incubation of SL9-TCR–transduced Jurkat/MA cells with synTac molecules (0.2 nM to 200 nM).