Ebola virus glycoprotein stimulates IL-18–dependent natural killer cell responses
Helen R. Wagstaffe, Elizabeth A. Clutterbuck, Viki Bockstal, Jeroen N. Stoop, Kerstin Luhn, Macaya Douoguih, Georgi Shukarev, Matthew D. Snape, Andrew J. Pollard, Eleanor M. Riley, Martin R. Goodier
Helen R. Wagstaffe, Elizabeth A. Clutterbuck, Viki Bockstal, Jeroen N. Stoop, Kerstin Luhn, Macaya Douoguih, Georgi Shukarev, Matthew D. Snape, Andrew J. Pollard, Eleanor M. Riley, Martin R. Goodier
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Clinical Research and Public Health Immunology

Ebola virus glycoprotein stimulates IL-18–dependent natural killer cell responses

Abstract

BACKGROUND NK cells are activated by innate cytokines and viral ligands to kill virus-infected cells. These functions are enhanced during secondary immune responses and after vaccination by synergy with effector T cells and virus-specific antibodies. In human Ebola virus infection, clinical outcome is strongly associated with the initial innate cytokine response, but the role of NK cells has not been thoroughly examined.METHODS The novel 2-dose heterologous Adenovirus type 26.ZEBOV (Ad26.ZEBOV) and modified vaccinia Ankara-BN-Filo (MVA-BN-Filo) vaccine regimen is safe and provides specific immunity against Ebola glycoprotein, and is currently in phase 2 and 3 studies. Here, we analyzed NK cell phenotype and function in response to Ad26.ZEBOV, MVA-BN-Filo vaccination regimen and in response to in vitro Ebola glycoprotein stimulation of PBMCs isolated before and after vaccination.RESULTS We show enhanced NK cell proliferation and activation after vaccination compared with baseline. Ebola glycoprotein–induced activation of NK cells was dependent on accessory cells and TLR-4–dependent innate cytokine secretion (predominantly from CD14+ monocytes) and enriched within less differentiated NK cell subsets. Optimal NK cell responses were dependent on IL-18 and IL-12, whereas IFN-γ secretion was restricted by high concentrations of IL-10.CONCLUSION This study demonstrates the induction of NK cell effector functions early after Ad26.ZEBOV, MVA-BN-Filo vaccination and provides a mechanism for the activation and regulation of NK cells by Ebola glycoprotein.TRIAL REGISTRATION ClinicalTrials.gov NCT02313077.FUNDING United Kingdom Medical Research Council Studentship in Vaccine Research, Innovative Medicines Initiative 2 Joint Undertaking, EBOVAC (grant 115861) and Crucell Holland (now Janssen Vaccines and Prevention B.V.), European Union’s Horizon 2020 research and innovation programme and European Federation of Pharmaceutical Industries and Associations (EFPIA).

Authors

Helen R. Wagstaffe, Elizabeth A. Clutterbuck, Viki Bockstal, Jeroen N. Stoop, Kerstin Luhn, Macaya Douoguih, Georgi Shukarev, Matthew D. Snape, Andrew J. Pollard, Eleanor M. Riley, Martin R. Goodier

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Figure 6

Regulation of NK cell IFN-γ production by EBOV GP induced IL-10.

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Regulation of NK cell IFN-γ production by EBOV GP induced IL-10. The cor...
The correlation between NK cell IFN-γ secretion determined by intracellular staining and IL-10 secretion measured by Luminex in response to EBOV GP (in baseline trial samples) was determined by Spearman’s coefficient (A) (n = 70). Nonvaccinated control PBMCs were stimulated in the presence of blocking antibodies against IL-10R or isotype control (n = 16). Total NK cell IFN-γ (B), CD107a (C), and CD25 (D) expression was determined. Intracellular IL-10 was also measured by flow cytometry (gating strategy as per Supplemental Figure 5A) in B cells (CD19+), myeloid DCs (mDC; CD14–CD11c+), total CD14– and total CD14+ cells, NK cells (CD3–CD56+), and T cells (CD3+) (E). The proportion of IL-10+ events per cell type determined by back-gating is also shown as a pie chart (F). Graphs show box-and-whisker plots with median, IQR (box), and 10th to 90th percentile (whiskers). Comparisons were performed using Wilcoxon signed-rank test. **P < 0.01, ***P < 0.001, ****P < 0.0001.