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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Immunol. | doi: 10.3389/fimmu.2019.02030

Activation of human NK cells by Bordetella pertussis requires Inflammasome activation in macrophages

 Michiel M. Kroes1, 2, Rob Mariman1, Daniëlle Hijdra1, Hendrik-Jan Hamstra1,  Karlijn J. van Boxtel1,  Jos P. van Putten2,  Jelle de Wit1 and  Elena Pinelli1*
  • 1Centre for Infectious Disease Control (RIVM), Netherlands
  • 2Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Netherlands

Pertussis is a highly contagious respiratory infection caused by the bacterium Bordetella pertussis. Humans are the only known natural reservoir of B. pertussis. In mice, macrophages and NK cells have a key role in confining B. pertussis to the respiratory tract. However, the mechanisms underlying this process, particularly during human infections, remain unclear. Here we characterized the activation of human macrophages and NK cells in response to B. pertussis and unraveled the role of inflammasomes in this process. NLRP3 inflammasome activation by B. pertussis in human macrophage-like THP-1 cells and primary monocyte-derived macrophages (mo-MΦ) was shown by the visualization of ASC-speck formation, pyroptosis, and the secretion of caspase-mediated IL-1β and IL-18. In contrast to macrophages, stimulation of human CD56+CD3- NK cells by B. pertussis alone did not result in activation of these cells. However, co-culture of B. pertussis-stimulated mo-MΦ and autologous NK cells resulted in high amounts of IFNγ secretion and an increased frequency of IL-2Rα+ and HLA-DR+ NK cells, indicating NK cell activation. This activation was significantly reduced upon inhibition of inflammasome activity or blocking of IL-18 in the mo-MΦ/NK cell co-culture. Furthermore, we observed increased secretion of proinflammatory cytokines in the B. pertussis-stimulated mo-MΦ/NK co-culture compared to the mo-MΦ single culture. Our results demonstrate that B. pertussis induces inflammasome activation in human macrophages and that the IL-18 produced by these cells is required for the activation of human NK cells, which in turn enhances the pro-inflammatory response to this pathogen. Our data provides a better understanding of the underlying mechanisms involved in the induction of innate immune responses against B. pertussis. These findings contribute to the knowledge required for the development of improved intervention strategies to control this highly contagious disease.

Keywords: NLRP3, crosstalk, Interferon - γ, IL-18, innate immuity, Bordetella pertussis, Inflammasome, human

Received: 26 Mar 2019; Accepted: 12 Aug 2019.

Copyright: © 2019 Kroes, Mariman, Hijdra, Hamstra, van Boxtel, van Putten, de Wit and Pinelli. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Elena Pinelli, Centre for Infectious Disease Control (RIVM), Bilthoven, 3720, Netherlands, elena.pinelli.ortiz@rivm.nl