SHP-1 phosphatase activity counteracts increased T cell receptor affinity
Michael Hebeisen, Lukas Baitsch, Danilo Presotto, Petra Baumgaertner, Pedro Romero, Olivier Michielin, Daniel E. Speiser, Nathalie Rufer
Michael Hebeisen, Lukas Baitsch, Danilo Presotto, Petra Baumgaertner, Pedro Romero, Olivier Michielin, Daniel E. Speiser, Nathalie Rufer
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Research Article Immunology

SHP-1 phosphatase activity counteracts increased T cell receptor affinity

Abstract

Anti-self/tumor T cell function can be improved by increasing TCR-peptide MHC (pMHC) affinity within physiological limits, but paradoxically further increases (Kd < 1 μM) lead to drastic functional declines. Using human CD8+ T cells engineered with TCRs of incremental affinity for the tumor antigen HLA-A2/NY-ESO-1, we investigated the molecular mechanisms underlying this high-affinity–associated loss of function. As compared with cells expressing TCR affinities generating optimal function (Kd = 5 to 1 μM), those with supraphysiological affinity (Kd = 1 μM to 15 nM) showed impaired gene expression, signaling, and surface expression of activatory/costimulatory receptors. Preferential expression of the inhibitory receptor programmed cell death-1 (PD-1) was limited to T cells with the highest TCR affinity, correlating with full functional recovery upon PD-1 ligand 1 (PD-L1) blockade. In contrast, upregulation of the Src homology 2 domain-containing phosphatase 1 (SHP-1/PTPN6) was broad, with gradually enhanced expression in CD8+ T cells with increasing TCR affinities. Consequently, pharmacological inhibition of SHP-1 with sodium stibogluconate augmented the function of all engineered T cells, and this correlated with the TCR affinity–dependent levels of SHP-1. These data highlight an unexpected and global role of SHP-1 in regulating CD8+ T cell activation and responsiveness and support the development of therapies inhibiting protein tyrosine phosphatases to enhance T cell–mediated immunity.

Authors

Michael Hebeisen, Lukas Baitsch, Danilo Presotto, Petra Baumgaertner, Pedro Romero, Olivier Michielin, Daniel E. Speiser, Nathalie Rufer

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Figure 1

Functionality, TCR-αβ surface expression levels, and TCR/CD8 downregulation in CD8+ T cells engineered with self/tumor-specific TCR of incremental affinities.

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Functionality, TCR-αβ surface expression levels, and TCR/CD8 downregulat...
(A) Ca2+ flux of TCR-transduced CD8+ T cells without (baseline) and with 1 μg/ml HLA-A2/NY-ESO–specific multimer stimulation. Maximal Ca2+ flux after ionomycin stimulation indicates equal capacity to mobilize calcium in all T cell variants. Data are expressed as Indo-1 (violet)/Indo-1 (blue) emission ratio. (B) Cytotoxic activity (% of maximal killing) against Me 275 and Me 290 (HLA-A2+/NY-ESO-1+) and Na8 (HLA-A2+/NY-ESO-1–) tumor cell lines at an effector target ratio of 10:1. (C) Percentage of primary CD8+ T cells expressing the affinity-optimized NY-ESO-1–specific TCRs as detected by A2/NY-ESO-1157–165–specific multimer staining (left panel). Cells with greater than 80% multimer labeling were used for further analysis. Surface expression levels (in MFI) of TCR β-chain BV13.1 (middle panel) and total αβTCR (right panel) are shown for all CD8+ transduced T cells. (D and E) Downregulation of CD8 coreceptor (D; in %) and TCR (E; in MFI) in engineered CD8+ T cells in the absence (baseline) or presence of 0.1 μg/ml unlabeled A2/NY-ESO-1–specific multimer. Data from T cells with reduced CD8 expression (D; CD8 low) are shown as percentage of total T cells (CD8 high and low). TCR downregulation following stimulation (E) is depicted as dark gray histograms or columns. Error bars represent mean ± SD.