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 4

pp65 synTac stimulates in vitro expansion of functional pp65-specific CD8+ T cells from HLA-A*0201 HIV-infected donors.

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pp65 synTac stimulates in vitro expansion of functional pp65-specific CD...
(A) PBMCs from HIV-seropositive donor OM265 were treated with the indicated synTacs (0.1 nM), cultured for 12 days in complete IMDM with IL-2 (100 U/mL) and Raltegravir (1 μM) and analyzed by flow cytometry. (B) Summary data from 7 different donors (OM265, HGLK9, CIRC0145, HGLK5, 603, 0315B, and 619) of pp65-specific CD8+ T cells after treatment with indicated synTacs are shown as mean ± SD with statistical analysis performed using ordinary 1-way ANOVA followed by Tukey’s multiple comparisons test. (C) Baseline level of CD28 or 4-1BBL expression from pp65-specific CD8+ T cells of 5 HIV-infected donors shown in B. (D) PD-1 (left), LAG-3 (middle), and TIM-3 (right) expression on SL9-specific (red shade) or pp65-specific (blue shaded) CD8+ T cells from HIV-seropositive donor 619. The numbers in each panel indicate the percentage positive for each marker compared with the isotype control (gray shaded). (E) Frequency of TN (naive, CD45RO–CCR7+), TCM (central memory, CD45RO+CCR7+), TTE (terminal effector, CD45RO–CCR7–), and TEM (effector memory, CD45RO+CCR7–) from pp65-specific CD8+ T cells expanded by pp65-synTac treatment of seropositive donor OM265 PBMCs. Data represent the mean ± SD of 2 independent experiments of this donor. (F) Intracellular cytokine expression of pp65-specific CD8+ T cells from 5 different donors expanded by treatment with the indicated synTac that expresses IFN-γ, TNF-α and IFN-γ, or CD107a and IFN-γ after stimulation with pp65- or SL9-peptide–pulsed T2 cells. (G) Cytolytic activity of synTac-expanded pp65-specific CD8+ T cells from HIV-seropositive donor HGLK5 directed at pp65- or SL9-peptide–pulsed T2 cells determined using EuTDA cytotoxicity assay cocultured at the indicated E/T ratios. Data shown represent mean ± SD of 3 experimental replicates and 2 independent experiments.