T cell receptor–targeted immunotherapeutics drive selective in vivo HIV- and CMV-specific T cell expansion in humanized mice
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
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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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 6

pp65-synTac expanded pp65-specific CD8+ T cells from a HIV-seronegative donor are polyfunctional and potently inhibit CMV infection.

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pp65-synTac expanded pp65-specific CD8+ T cells from a HIV-seronegative ...
(A) Frequency of pp65-specific cells that are TN, TCM, TTE, and TEM. Data represent 2 independent experiments showing mean ± SD. (B and C) Intracellular cytokine staining of IFN-γ and TNF-α (upper panels) or CD107a and IFN-γ (lower panels), in pp65-specific CD8+ T cells expanded by treatment with the indicated synTac after overnight stimulation with (B) pp65- or (C) SL9-pulsed T2 cells. Dot plots shown were gated from the pp65-tetramer+ population and are representative of 2 independent experiments. (D) Quantification of cells that express IFN-γ, TNF-α and IFN-γ, TNF-α, and IFN-γ and CD107a combined from 2 independent experiments showing mean ± SD and statistically analyzed using ordinary 1-way ANOVA followed by Tukey’s multiple comparisons test. (E) Twelve days after treatment with the indicated synTac, cytolytic activity directed at pp65- or SL9-peptide–pulsed T2 cells was evaluated after 4-hour culture at the indicated E/T ratios using an EuTDA cytotoxicity assay. Data shown represent mean ± SD of 3 experimental replicates and are representative of 2 independent experiments. (F and G) PBMCs treated with the indicated synTac (0.1 nM) for 7 days were cocultured with HLA-A*0201–expressing human fibroblasts infected with a recombinant CMV-luc (MOI = 3) at E/T ratios of (F) 1:2 and (G) 1:5. After 3 days, luciferase activity was measured. Results from an experiment representative of 2 independent experiments are shown and statistical analysis was performed using Tukey’s multiple comparisons test.