Dr. Valentina Venzin

France

CD4+ T cells license Kupffer cells to produce IL-27 and reverse CD8+ T cell dysfunction induced by hepatocellular priming

Valentina Venzin1,2, Cristian G. Beccaria1,2, Chiara Perucchini1,2, Pietro Delfino1, Elisa B. Bono1, Leonardo Giustini1, Federica Moalli1,3, Marta Grillo1,2, Valeria Fumagalli1,2, Chiara Laura1,2,4, Pietro Di Lucia1,2, Katharina Reinhard5, Jutta Petschenka6, Tana Annmarie Omokoko5, Anna Celant1,2, Sabrina Ottolini7,8, Keigo Kawashima1, Micol Ravà1,2, Marco De Giovanni1, Donato Inverso1,2, Mirela Kuka1,2, Patrick T. F. Kennedy9, Martin Guilliams10,11, Giulia Casorati1, Federica Pedica12, Maurilio Ponzoni12, Uğur Şahin5,13, Nina Le Bert7, Antonio Bertoletti7, Fulvia Vascotto13, Luca G. Guidotti1,2, and Matteo Iannacone1,2,3

1. Division of Immunology, Transplantation, and Infectious Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy
2. Vita-Salute San Raffaele University, Milan, Italy
3. Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan, Italy
4. Center for Omics Sciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
5. Biopharmaceutical New Technologies (BioNTech), BioNTech Cell & Gene Therapies GmbH, An der Goldgrube 12, 55131 Mainz, Germany
6. Boehringer Ingelheim International GmbH, Ingelheim am Rhein, Germany
7. Emerging Infectious Disease Program, Duke-NUS Medical School, Singapore, Singapore
8. Department of Molecular Medicine, University of Pavia, 27100 Pavia, Italy
9. Department of Hepatology, Centre for Immunobiology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
10. Laboratory Lab of Myeloid Cell Biology in Tissue Homeostasis and Regeneration, VIB-UGent Center for Inflammation Research
11. Department of Biomedical Molecular Biology, Faculty of Sciences, Ghent University, Ghent, Belgium
12. Vita-Salute San Raffaele University, Pathology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
13. TRON, Translational Oncology at the University Medical Center of the Johannes Gutenberg University Mainz gGmbH, Mainz, Germany

Abstract

Background

Efficient priming of CD8⁺T cell responses against non-cytolytic pathogens like HBV is believed to rely on CD4⁺T cell help. However, where when and how this issue occurs has never been described or mechanistically elucidated.

Methods

We took advantage of unique HBV transgenic mouse models, in which we have demonstrated that adoptive transferred HBV-specific CD8⁺T cells that recognize hepatocellular viral antigens undergo activation and proliferation but fail to differentiate into antiviral effector cells. To understand the extent to which CD4+T cells help intrahepatic CD8+T cell differentiation, we generated HBV-specific CD4⁺ TCR transgenic mice (Env126), where all CD4⁺T cells recognize an I-Ab-restricted T cell epitope of the HBV envelope protein.

Results

Adoptive transfer of TH1-like Env126 effector CD4⁺T cells in HBV-transgenic mice counteracts the CD8⁺T cell dysfunction induced by hepatocellular priming, boosting their proliferation and effector functions. This enhances T cell-mediated liver immunopathology and suppresses viral replication. Contrary to immunological dogma, CD4⁺T cell help occurs locally within the liver, bypassing secondary lymphoid organs and surprisingly, Kupffer cells, not dendritic cells, mediate intrahepatic T cell cooperation. Multiphoton microscopy reveals their simultaneous interaction with KCs, and as such, CD4⁺T cell help is lost upon KC depletion. Mechanistically, CD4⁺T cells engage KCs via CD40-CD40L interactions, leading to IL-12 and IL-27 production. IL-12 promotes CD4⁺T cell expansion, while IL-27 reinvigorates CD8⁺T cell response. Finally, therapeutic IL-27 administration restores HBV-specific CD8⁺T cell responses in both HBV-transgenic mice and T cells isolated from chronic HBV patients.

Conclusions

Our findings reveal a novel mechanism of CD4⁺ T cell help to CD8⁺ T cells that occurs outside secondary lymphoid organs, specifically in the liver, and involves antigen-presenting cells other than conventional dendritic cells. The described cellular and molecular mechanisms offer new insights for immunotherapeutic strategies against chronic hepatic infections and their life-threatening complications.