Chronic stimulation drives human NK cell dysfunction and epigenetic reprograming
Aimee Merino, … , Jeffrey S. Miller, Frank Cichocki
Aimee Merino, … , Jeffrey S. Miller, Frank Cichocki
Published June 18, 2019
Citation Information: J Clin Invest. 2019;129(9):3770-3785. https://doi.org/10.1172/JCI125916.
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Research Article Immunology

Chronic stimulation drives human NK cell dysfunction and epigenetic reprograming

Abstract

A population of NK cells expressing the activating receptor NKG2C and the maturation marker CD57 expands in response to human CMV (HCMV) infection. CD3–CD56dimCD57+NKG2C+ NK cells are similar to CD8+ memory T cells with rapid and robust effector function upon restimulation, persistence, and epigenetic remodeling of the IFNG locus. Chronic antigen stimulation drives CD8+ memory T cell proliferation, while also inducing genome-wide epigenetic reprograming and dysfunction. We hypothesized that chronic stimulation could similarly induce epigenetic reprograming and dysfunction in NK cells. Here, we show that chronic stimulation of adaptive NK cells through NKG2C using plate-bound agonistic Abs in combination with IL-15 drove robust proliferation and activation of CD3–CD56dimCD57+NKG2C+ NK cells, while simultaneously inducing high expression of the checkpoint inhibitory receptors LAG-3 and PD-1. Marked induction of checkpoint inhibitory receptors was also observed on the surface of adaptive NK cells cocultured with HCMV-infected endothelial cells. Chronically stimulated adaptive NK cells were dysfunctional when challenged with tumor targets. These cells exhibited a pattern of epigenetic reprograming, with genome-wide alterations in DNA methylation. We believe our study has important implications for cancer immunotherapy and propose that exhausted NK cells could be targeted with inhibitory checkpoint receptor blockade.

Authors

Aimee Merino, Bin Zhang, Philip Dougherty, Xianghua Luo, Jinhua Wang, Bruce R. Blazar, Jeffrey S. Miller, Frank Cichocki

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Figure 7

Adaptive NK cells cocultured with HCMV-infected HUVECs upregulate LAG-3 and PD-1 and exhibit impaired IFN-γ production.

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Adaptive NK cells cocultured with HCMV-infected HUVECs upregulate LAG-3 ...
HUVECs were infected with a GFP-expressing TB40/e clinical strain of HCMV at a MOI of 0.5 or spun down in parallel without virus (mock-infected) and used for 7-day coculture experiments with CD3/CD19-depleted PBMCs from HCMV-seropositive donors (n = 4). Cultures contained 10 ng/ml IL-15. (A) Representative FACS plots and summary data of the percentages of CD3–CD56+NKG2C+ cells from mock-infected and TB40/e-infected HUVEC cocultures. (B) Representative FACS plots and summary data of the percentages of CD3–CD56+NKG2C– and CD3–CD56+NKG2C+ NK cells expressing CD45RO and CD45RO MFI on each cell subset (n = 4). (C) Representative FACS plots and summary data of LAG-3 and PD-1 expression on CD3–CD56+NKG2C– and CD3–CD56+NKG2C+ NK cells from mock- and TB40/e-infected HUVEC cocultures (n = 4). (D) Summary data of intracellular IFN-γ in CD3–CD56+ NK cells gated by NKG2C and LAG-3 expression from mock-infected and TB40/e-infected HUVEC cocultures stimulated with K562 cells at an E/T ratio of 2:1 (n = 4). Results are from 2 independent experiments. *P ≤ 0.05 and **P ≤ 0.01, by paired t test. P values of multiple group comparisons (A, 4 pairwise comparisons as shown; B, same comparisons as in A) were adjusted using the Hommel method.