K+ Efflux-Independent NLRP3 Inflammasome Activation by Small Molecules Targeting Mitochondria

Christina J Groß; Ritu Mishra; Katharina S Schneider; Guillaume Médard; Jennifer Wettmarshausen; Daniela C Dittlein; Hexin Shi; Oliver Gorka; Paul-Albert Koenig; Stephan Fromm; Giovanni Magnani; Tamara Ćiković; Lara Hartjes; Joachim Smollich; Avril A B Robertson; Matthew A Cooper; Marc Schmidt-Supprian; Michael Schuster; Kate Schroder; Petr Broz; Claudia Traidl-Hoffmann; Bruce Beutler; Bernhard Kuster; Jürgen Ruland; Sabine Schneider; Fabiana Perocchi; Olaf Groß

doi:10.1016/j.immuni.2016.08.010

K⁺ Efflux-Independent NLRP3 Inflammasome Activation by Small Molecules Targeting Mitochondria

Immunity. 2016 Oct 18;45(4):761-773. doi: 10.1016/j.immuni.2016.08.010. Epub 2016 Sep 27.

Authors

Christina J Groß¹, Ritu Mishra¹, Katharina S Schneider¹, Guillaume Médard², Jennifer Wettmarshausen³, Daniela C Dittlein⁴, Hexin Shi⁵, Oliver Gorka¹, Paul-Albert Koenig¹, Stephan Fromm⁶, Giovanni Magnani¹, Tamara Ćiković¹, Lara Hartjes¹, Joachim Smollich¹, Avril A B Robertson⁷, Matthew A Cooper⁷, Marc Schmidt-Supprian⁸, Michael Schuster⁶, Kate Schroder⁷, Petr Broz⁹, Claudia Traidl-Hoffmann⁴, Bruce Beutler⁵, Bernhard Kuster¹⁰, Jürgen Ruland¹¹, Sabine Schneider¹², Fabiana Perocchi³, Olaf Groß¹³

Affiliations

¹ Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar, Technische Universität München (TUM), 81675 Munich, Germany.
² Chair of Proteomics and Bioanalytics, TUM, 85354 Freising, Germany.
³ Genzentrum, Department of Biochemistry, Ludwig-Maximilians-Universität München, 81377 Munich, and Institute of Human Genetics, Helmholtz Zentrum München, 85764 Neuherberg, Germany.
⁴ Chair and Institute of Environmental Medicine, UNIKA-T, TUM, 86156 Augsburg, and Helmholtz Zentrum München, 85764 Neuherberg, Germany.
⁵ Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
⁶ Fachgruppe Analytische Chemie, Department of Chemistry, TUM, 85748 Garching, Germany.
⁷ Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4067, Australia.
⁸ Department of Hematology and Oncology, Klinikum rechts der Isar, TUM, 81675 Munich, Germany; TranslaTUM: Zentralinstitut für translationale Krebsforschung, TUM, 81675 Munich, Germany.
⁹ Focal Area Infection Biology, Biozentrum, University of Basel, 4003 Basel, Switzerland.
¹⁰ Chair of Proteomics and Bioanalytics, TUM, 85354 Freising, Germany; Center for Integrated Protein Science Munich (CIPSM), 81377 Munich, Germany.
¹¹ Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar, Technische Universität München (TUM), 81675 Munich, Germany; TranslaTUM: Zentralinstitut für translationale Krebsforschung, TUM, 81675 Munich, Germany.
¹² Department of Chemistry, TUM, 85748 Garching, Germany; Center for Integrated Protein Science Munich (CIPSM), 81377 Munich, Germany.
¹³ Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar, Technische Universität München (TUM), 81675 Munich, Germany; TranslaTUM: Zentralinstitut für translationale Krebsforschung, TUM, 81675 Munich, Germany. Electronic address: olaf.gross@tum.de.

PMID: 27692612
DOI: 10.1016/j.immuni.2016.08.010

Abstract

Imiquimod is a small-molecule ligand of Toll-like receptor-7 (TLR7) that is licensed for the treatment of viral infections and cancers of the skin. Imiquimod has TLR7-independent activities that are mechanistically unexplained, including NLRP3 inflammasome activation in myeloid cells and apoptosis induction in cancer cells. We investigated the mechanism of inflammasome activation by imiquimod and the related molecule CL097 and determined that K⁺ efflux was dispensable for NLRP3 activation by these compounds. Imiquimod and CL097 inhibited the quinone oxidoreductases NQO2 and mitochondrial Complex I. This induced a burst of reactive oxygen species (ROS) and thiol oxidation, and led to NLRP3 activation via NEK7, a recently identified component of this inflammasome. Metabolic consequences of Complex I inhibition and endolysosomal effects of imiquimod might also contribute to NLRP3 activation. Our results reveal a K⁺ efflux-independent mechanism for NLRP3 activation and identify targets of imiquimod that might be clinically relevant.

MeSH terms

Animals
Electron Transport Complex I / metabolism
Inflammasomes / metabolism*
Mice
Mitochondria / drug effects*
Mitochondria / metabolism*
NIMA-Related Kinases / metabolism
NLR Family, Pyrin Domain-Containing 3 Protein / metabolism*
Potassium / metabolism*
Quinone Reductases / metabolism
RNA, Small Nuclear / pharmacology*
Reactive Oxygen Species / metabolism
Toll-Like Receptor 7 / metabolism

Substances

Inflammasomes
NLR Family, Pyrin Domain-Containing 3 Protein
Nlrp3 protein, mouse
RNA, Small Nuclear
Reactive Oxygen Species
Toll-Like Receptor 7
NRH - quinone oxidoreductase2
Quinone Reductases
NIMA-Related Kinases
Electron Transport Complex I
Potassium