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
View: Text | PDF
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

×

Figure 5

Myeloid accessory cell cytokine-dependent NK cell activation.

Options: View larger image (or click on image) Download as PowerPoint
Myeloid accessory cell cytokine-dependent NK cell activation. Nonvaccina...
Nonvaccinated control PBMCs, purified NK cells, or purified NK cells plus CD14+ monocyte–enriched population (mono) were stimulated with EBOV GP (A–C) (n = 5). PBMCs were also left unstimulated or stimulated with EBOV GP in the presence of blocking antibodies against IL-12 and IL-18 or appropriate isotype control (Iso.) (n = 16). NK cell function was analyzed by flow cytometry. Graphs show CD56bright IFN-γ, CD107a, and CD25 expression (A–C), total NK cell CD25 MFI (D) or percentage (E), or CD56bright CD25 MFI (F) or percentage (G), and total NK cell CD107a (H) and IFN-γ expression (I). Concentrations of IL-18 in culture supernatant and intracellular IL-12 expression were determined by ELISA and flow cytometry respectively, the relationship between IL-18 and total NK cell CD25 expression was determined by Spearman’s coefficient (J–L). IL-12(p40)+ B cells (CD19+), myeloid DC (mDC; CD19–CD14–CD11c+), total CD14–, and total CD14+ cells were gated as per gating strategy in Supplemental Figure 5A. Graphs show box-and-whisker plots with median, IQR (box), and 10th to 90th percentile (whiskers) or 1 point per donor. Comparisons were performed using Wilcoxon signed-rank test and correlations were determined using Spearman’s correlation. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.