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 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 1

Therapeutic antitumor effect of PD-1 or PD-L1 antibodies dependent on NK cells.

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Therapeutic antitumor effect of PD-1 or PD-L1 antibodies dependent on NK...
(A) NK, CD4+, and/or CD8+ T cells were depleted before s.c. injection of 106 RMA-S cells. Tumor volumes (mean ± SEM) are shown. Experiments depicted are representative of 2 performed. n = 4–5/group. Two-way ANOVA. ***P < 0.001. (B) PD-L1 expression was analyzed on cells stimulated or not with 20 ng/ml IFN-γ for 48 hours. Experiments depicted are representative of 3 performed. (C) 2 × 106 RMA-S or RMA-S–Pdl1 cells (naturally expressing CD45.2) or TRAMP-C2 cells (transduced with Thy1.1) were injected s.c. into C57BL/6J-CD45.1+ mice, and PD-L1 expression was analyzed on splenic or intratumoral cells, gating on dendritic cells (viable CD45.1+CD3–CD19–Ter119–NK1.1–CD11b+Ly6G–CD11chi), monocytes (viable CD45.1+CD3–CD19–Ter119–NK1.1–CD11b+Ly6G–CD11c–Ly6C+), and tumor cells (viable CD45.1–CD45.2+ cells for RMA-S and RMA-S–Pdl1; or viable CD45.2–Thy1.1+ cells for TRAMP-C2). The MFI of isotype control–stained cells was subtracted from the MFI of PD-L1–stained cells. Two experiments were pooled (n = 5–7/group). (D) 106 RMA-S–Pdl1 cells were injected in mice depleted of NK or CD8+ or CD4+ T cells. Tumor volumes (mean ± SEM) are shown. Experiments depicted are representative of 2 performed. n = 4–5/group. Two-way ANOVA. **P < 0.01. (E) 106 RMA-S–Pdl1 cells were injected in C57BL/6J mice, and after 2 days, 250 μg PD-1 or control antibody was administered. Some mice were depleted of NK cells 2 days before tumor cell injection. Pooled data from 2 of the 3 experiments performed are shown. n = 6–11/group. Two-way ANOVA. Both NK-depleted groups were significantly different than the corresponding undepleted groups. (F) 106 RMA-S–Pdl1 cells were injected, and tumors were allowed to grow to an average of 25 mm3, at which time (and 2 days later), mice were treated with 250 μg PD-1 antibody or control antibody. Experiments shown are representative of 2 performed. n = 5/group. Two-way ANOVA. (G–H) 0.5 × 106 RMA-S–Pdl1 tumor cells were mixed with Matrigel and either 20 μg anti–PD-1 or control Ig (E, G) or anti–PD-L1 or control Ig (F, H) and injected s.c. in C57BL/6 mice. Experiments were repeated at least 2 times, with n = 4–5/group. Two-way ANOVA.