Contribution of NK cells to immunotherapy mediated by PD-1/PD-L1 blockade
Joy Hsu, … , David H. Raulet, Michele Ardolino
Joy Hsu, … , David H. Raulet, Michele Ardolino
Published October 1, 2018; First published September 10, 2018
Citation Information: J Clin Invest. 2018;128(10):4654-4668. https://doi.org/10.1172/JCI99317.
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Research Article Immunology

Contribution of NK cells to immunotherapy mediated by PD-1/PD-L1 blockade

Abstract

Checkpoint blockade immunotherapy targeting the PD-1/PD-L1 inhibitory axis has produced remarkable results in the treatment of several types of cancer. Whereas cytotoxic T cells are known to provide important antitumor effects during checkpoint blockade, certain cancers with low MHC expression are responsive to therapy, suggesting that other immune cell types may also play a role. Here, we employed several mouse models of cancer to investigate the effect of PD-1/PD-L1 blockade on NK cells, a population of cytotoxic innate lymphocytes that also mediate antitumor immunity. We discovered that PD-1 and PD-L1 blockade elicited a strong NK cell response that was indispensable for the full therapeutic effect of immunotherapy. PD-1 was expressed on NK cells within transplantable, spontaneous, and genetically induced mouse tumor models, and PD-L1 expression in cancer cells resulted in reduced NK cell responses and generation of more aggressive tumors in vivo. PD-1 expression was more abundant on NK cells with an activated and more responsive phenotype and did not mark NK cells with an exhausted phenotype. These results demonstrate the importance of the PD-1/PD-L1 axis in inhibiting NK cell responses in vivo and reveal that NK cells, in addition to T cells, mediate the effect of PD-1/PD-L1 blockade immunotherapy.

Authors

Joy Hsu, Jonathan J. Hodgins, Malvika Marathe, Chris J. Nicolai, Marie-Claude Bourgeois-Daigneault, Troy N. Trevino, Camillia S. Azimi, Amit K. Scheer, Haley E. Randolph, Thornton W. Thompson, Lily Zhang, Alexandre Iannello, Nikhita Mathur, Karen E. Jardine, Georgia A. Kirn, John C. Bell, Michael W. McBurney, David H. Raulet, Michele Ardolino

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Figure 2

PD-1 is expressed on tumor-infiltrating NK cells and suppresses NK cell cytotoxicity in vitro.

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PD-1 is expressed on tumor-infiltrating NK cells and suppresses NK cell ...
(A–B) C57BL/6J mice were injected s.c. with 2 × 106 RMA-S cells or PBS; BALB/cJ mice were injected with 0.5 × 106 CT26 cells. PD-1 expression was assessed after 13 days on NK cells from spleens, axillary LNs, inguinal LNs, and tumors. Staining for PD-1 (dark gray histograms) or control IgG (cIg) (light gray histograms) is shown. NK cells were gated as viable Ter119–CD3–CD19–F4/80–NKp46+ cells in BALB/cJ or Ter119–CD3–CD19–F4/80–NKp46+NK1.1+ cells in C57BL/6J mice. Experiments shown are representative of 6 performed. n = 3–5. (C) Summary of PD-1 expression on intratumoral NK and CD8+ T cells in mice injected with RMA, RMA-S, B16, C1498, CT26, 4T1, or A20 cells or on intratumoral NK cells in the prostates or thymi from spontaneous cancer models (TRAMP and Eu-Myc models, respectively) or in KP sarcomas. PD-1 expression on NK cells in each model was assessed in at least 3 independent experiments with at least n = 3. (D–E) IL-2–activated NK cells previously transduced with a Pdcd1 expression vector were stimulated with RMA-S or RMA-S–Pdl1 cells at different T/E ratios before determining degranulation (D) and IFN-γ production (E) of PD-1+ NK cells. Experiments depicted are representative of 3 performed. Every T/E ratio is shown as average ± SD of 3 technical replicates. Two-way ANOVA. (F–G) NK92 cells transduced with Pdcd1 (Pdcd1 encodes PD-1) or an empty vector were stimulated with K562 or K562-Pdl1 cells, and lysis of target cells (F) or degranulation of effector cells (G) was assessed by flow cytometry. Data shown in F and G are representative of 4 and 2 experiments performed, respectively. Every T/E ratio shows the average of 3 technical replicates. Note that in instances in which responses increase with more target cells, we plotted T/E ratios, wherease in cases in which the response increases with more effector cells, we plotted E/T ratios. Two-way ANOVA with repeated measures.