Sukumar Namineni1, Tracy O'Connor2, Suzanne Faure-Dupuy3, Pål Johansen4, Tobias Riedl3, Kaijing Liu5, Haifeng Xu6, Indrabahadur Singh7, Prashant Shinde8, Fanghui Li6, Aleksandra Pandyra6, Piyush Sharma9, Marc Ringelhan10, Andreas Muschaweckh11, Katharina Borst12, Patrick Blank12, Sandra Lampl13, Katharina Neuhaus3, David Durantel14, Rayan Farhat14, Achim Weber15, Daniela Lenggenhager15, Thomas M Kündig4, Peter Staeheli16, Ulrike Protzer17, Dirk Wohlleber13, Bernhard Holzmann18, Marco Binder19, Kai Breuhahn5, Lisa Mareike Assmus20, Jacob Nattermann21, Zeinab Abdullah20, Maude Rolland22, Emmanuel Dejardin22, Philipp A Lang8, Karl S Lang6, Michael Karin23, Julie Lucifora14, Ulrich Kalinke12, Percy A Knolle13, Mathias Heikenwalder24. 1. Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Virology, Technical University of Munich and Helmholtz Zentrum München, Schneckenburgerstrasse 8, 81675 Munich, Germany; Institute of Molecular Immunology and Experimental Oncology, Technical University of Munich, Ismaningerstraße 22, 81675 Munich, Germany. 2. Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Molecular Immunology and Experimental Oncology, Technical University of Munich, Ismaningerstraße 22, 81675 Munich, Germany. 3. Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany. 4. Department of Dermatology, University Hospital Zurich and University of Zurich, Gloriastrasse 31, 8091 Zurich, Switzerland. 5. Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany. 6. Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Hufelandstr. 55, Essen 45147, Germany. 7. Emmy Noether Research Group Epigenetic Machineries and Cancer, Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany. 8. Department of Molecular Medicine II, Medical Faculty, Heinrich Heine University, Universitätstr.1, 40225 Düsseldorf, Germany. 9. Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Hufelandstr. 55, Essen 45147, Germany; Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA, 38105. 10. Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Virology, Technical University of Munich and Helmholtz Zentrum München, Schneckenburgerstrasse 8, 81675 Munich, Germany; Department of Internal Medicine II, University Hospital rechts der Isar, Technical University of Munich, Ismaninger Str. 22, 81675 Munich, Germany. 11. Klinikum rechts der Isar, Department of Neurology, Technical University of Munich, Ismaninger Str. 22, 81675 Munich, Germany. 12. Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Hanover Medical School and the Helmholtz Centre for Infection Research, Brunswick, Germany. 13. Institute of Molecular Immunology and Experimental Oncology, Technical University of Munich, Ismaningerstraße 22, 81675 Munich, Germany. 14. INSERM, U1052, Cancer Research Center of Lyon (CRCL), Université de Lyon (UCBL1), CNRS UMR 5286, Centre Léon Bérard, Lyon, France. 15. Department of Pathology and Molecular Pathology, University Hospital of Zurich, 8091 Zurich, Switzerland. 16. Institute of Virology, University of Freiburg, Freiburg, Germany. 17. Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Virology, Technical University of Munich and Helmholtz Zentrum München, Schneckenburgerstrasse 8, 81675 Munich, Germany. 18. Department of Surgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany. 19. Research Group "Dynamics of Early Viral Infection and the Innate Antiviral Response", Division Virus-Associated Carcinogenesis (F170), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany. 20. Institute of Experimental Immunology, Bonn, Germany. 21. Department of Internal Medicine, University of Bonn, Bonn, Germany. 22. Laboratory of Molecular Immunology and Signal Transduction, GIGA-Institute, University of Liège, 4000 Liège, Belgium. 23. Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California San Diego (UCSD), 9500 Gilman Drive, La Jolla, California 92093, USA. 24. Division of Chronic Inflammation and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Virology, Technical University of Munich and Helmholtz Zentrum München, Schneckenburgerstrasse 8, 81675 Munich, Germany; Institute of Molecular Immunology and Experimental Oncology, Technical University of Munich, Ismaningerstraße 22, 81675 Munich, Germany. Electronic address: m.heikenwaelder@dkfz-heidelberg.de.
Abstract
BACKGROUND & AIMS: Hepatic innate immune control of viral infections has largely been attributed to Kupffer cells, the liver-resident macrophages. However, hepatocytes, the parenchymal cells of the liver, also possess potent immunological functions in addition to their known metabolic functions. Owing to their abundance in the liver and known immunological functions, we aimed to investigate the direct antiviral mechanisms employed by hepatocytes. METHODS: Using lymphocytic choriomeningitis virus (LCMV) as a model of liver infection, we first assessed the role of myeloid cells by depletion prior to infection. We investigated the role of hepatocyte-intrinsic innate immune signaling by infecting mice lacking canonical NF-κB signaling (IkkβΔHep) specifically in hepatocytes. In addition, mice lacking hepatocyte-specific interferon-α/β signaling-(IfnarΔHep), or interferon-α/β signaling in myeloid cells-(IfnarΔMyel) were infected. RESULTS: Here, we demonstrate that LCMV activates NF-κB signaling in hepatocytes. LCMV-triggered NF-κB activation in hepatocytes did not depend on Kupffer cells or TNFR1 signaling but rather on Toll-like receptor signaling. LCMV-infected IkkβΔHep livers displayed strongly elevated viral titers due to LCMV accumulation within hepatocytes, reduced interferon-stimulated gene (ISG) expression, delayed intrahepatic immune cell influx and delayed intrahepatic LCMV-specific CD8+ T cell responses. Notably, viral clearance and ISG expression were also reduced in LCMV-infected primary hepatocytes lacking IKKβ, demonstrating a hepatocyte-intrinsic effect. Similar to livers of IkkβΔHep mice, enhanced hepatocytic LCMV accumulation was observed in livers of IfnarΔHep mice, whereas IfnarΔMyel mice were able to control LCMV infection. Hepatocytic NF-κB signaling was also required for efficient ISG induction in HDV-infected dHepaRG cells and interferon-α/β-mediated inhibition of HBV replication in vitro. CONCLUSIONS: Together, these data show that hepatocyte-intrinsic NF-κB is a vital amplifier of interferon-α/β signaling, which is pivotal for strong early ISG responses, immune cell infiltration and hepatic viral clearance. LAY SUMMARY: Innate immune cells have been ascribed a primary role in controlling viral clearance upon hepatic infections. We identified a novel dual role for NF-κB signaling in infected hepatocytes which was crucial for maximizing interferon responses and initiating adaptive immunity, thereby efficiently controlling hepatic virus replication.
BACKGROUND & AIMS: Hepatic innate immune control of viral infections has largely been attributed to Kupffer cells, the liver-resident macrophages. However, hepatocytes, the parenchymal cells of the liver, also possess potent immunological functions in addition to their known metabolic functions. Owing to their abundance in the liver and known immunological functions, we aimed to investigate the direct antiviral mechanisms employed by hepatocytes. METHODS: Using lymphocytic choriomeningitis virus (LCMV) as a model of liver infection, we first assessed the role of myeloid cells by depletion prior to infection. We investigated the role of hepatocyte-intrinsic innate immune signaling by infecting mice lacking canonical NF-κB signaling (IkkβΔHep) specifically in hepatocytes. In addition, mice lacking hepatocyte-specific interferon-α/β signaling-(IfnarΔHep), or interferon-α/β signaling in myeloid cells-(IfnarΔMyel) were infected. RESULTS: Here, we demonstrate that LCMV activates NF-κB signaling in hepatocytes. LCMV-triggered NF-κB activation in hepatocytes did not depend on Kupffer cells or TNFR1 signaling but rather on Toll-like receptor signaling. LCMV-infected IkkβΔHep livers displayed strongly elevated viral titers due to LCMV accumulation within hepatocytes, reduced interferon-stimulated gene (ISG) expression, delayed intrahepatic immune cell influx and delayed intrahepatic LCMV-specific CD8+ T cell responses. Notably, viral clearance and ISG expression were also reduced in LCMV-infected primary hepatocytes lacking IKKβ, demonstrating a hepatocyte-intrinsic effect. Similar to livers of IkkβΔHep mice, enhanced hepatocytic LCMV accumulation was observed in livers of IfnarΔHep mice, whereas IfnarΔMyel mice were able to control LCMVinfection. Hepatocytic NF-κB signaling was also required for efficient ISG induction in HDV-infected dHepaRG cells and interferon-α/β-mediated inhibition of HBV replication in vitro. CONCLUSIONS: Together, these data show that hepatocyte-intrinsic NF-κB is a vital amplifier of interferon-α/β signaling, which is pivotal for strong early ISG responses, immune cell infiltration and hepatic viral clearance. LAY SUMMARY: Innate immune cells have been ascribed a primary role in controlling viral clearance upon hepatic infections. We identified a novel dual role for NF-κB signaling in infected hepatocytes which was crucial for maximizing interferon responses and initiating adaptive immunity, thereby efficiently controlling hepatic virus replication.