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Gaul S, Leszczynska A, Alegre F, Kaufmann B, Johnson CD, Adams LA, Wree A, Damm G, Seehofer D, Calvente CJ, Povero D, Kisseleva T, Eguchi A, McGeough MD, Hoffman HM, Pelegrin P, Laufs U, Feldstein AE. Hepatocyte pyroptosis and release of inflammasome particles induce stellate cell activation and liver fibrosis. J Hepatol 2021; 74:156-167. [PMID: 32763266 PMCID: PMC7749849 DOI: 10.1016/j.jhep.2020.07.041] [Citation(s) in RCA: 250] [Impact Index Per Article: 83.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 07/13/2020] [Accepted: 07/28/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS Increased hepatocyte death contributes to the pathology of acute and chronic liver diseases. However, the role of hepatocyte pyroptosis and extracellular inflammasome release in liver disease is unknown. METHODS We used primary mouse and human hepatocytes, hepatocyte-specific leucine 351 to proline Nlrp3KICreA mice, and GsdmdKO mice to investigate pyroptotic cell death in hepatocytes and its impact on liver inflammation and damage. Extracellular NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasomes were isolated from mutant NLRP3-YFP HEK cells and internalisation was studied in LX2 and primary human hepatic stellate cells. We also examined a cohort of 154 adult patients with biopsy-proven non-alcoholic fatty liver disease (Sir Charles Gairdner Hospital, Nedlands, Western Australia). RESULTS We demonstrated that primary mouse and human hepatocytes can undergo pyroptosis upon NLRP3 inflammasome activation with subsequent release of NLRP3 inflammasome proteins that amplify and perpetuate inflammasome-driven fibrogenesis. Pyroptosis was inhibited by blocking caspase-1 and gasdermin D activation. The activated form of caspase-1 was detected in the livers and in serum from patients with non-alcoholic steatohepatitis and correlated with disease severity. Nlrp3KICreA mice showed spontaneous liver fibrosis under normal chow diet, and increased sensitivity to liver damage and inflammation after treatment with low dose lipopolysaccharide. Mechanistically, hepatic stellate cells engulfed extracellular NLRP3 inflammasome particles leading to increased IL-1β secretion and α-smooth muscle actin expression. This effect was abrogated when cells were pre-treated with the endocytosis inhibitor cytochalasin B. CONCLUSIONS These results identify hepatocyte pyroptosis and release of inflammasome components as a novel mechanism to propagate liver injury and liver fibrosis development. LAY SUMMARY Our findings identify a novel mechanism of inflammation in the liver. Experiments in cell cultures, mice, and human samples show that a specific form of cell death, called pyroptosis, leads to the release of complex inflammatory particles, the NLRP3 inflammasome, from inside hepatocytes into the extracellular space. From there they are taken up by other cells and thereby mediate inflammatory and pro-fibrogenic stress signals. The discovery of this mechanism may lead to novel treatments for chronic liver diseases in the future.
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Affiliation(s)
- Susanne Gaul
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA; Universität Leipzig, Klinik und Poliklinik für Kardiologie, Leipzig, Germany
| | | | - Fernando Alegre
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA; Department of Pharmacology, Faculty of Medicine, University of Valencia, Valencia, Spain
| | - Benedikt Kaufmann
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Casey D Johnson
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA; University of California Irvine, Irvine, CA, USA
| | - Leon A Adams
- Medical School, University of Western Australia, Perth, Australia
| | - Alexander Wree
- Department of Hepatology and Gastroenterology, Charité, Campus Virchow Klinikum and Charité, Universitätsmedizin Berlin, Berlin, Germany
| | - Georg Damm
- Department of Hepatobiliary Surgery and Visceral Transplantation, University Hospital, Leipzig University, Leipzig, Germany
| | - Daniel Seehofer
- Department of Hepatobiliary Surgery and Visceral Transplantation, University Hospital, Leipzig University, Leipzig, Germany
| | - Carolina J Calvente
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Davide Povero
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Tatiana Kisseleva
- Department of Surgery, University of California San Diego, La Jolla, CA, USA
| | - Akiko Eguchi
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA; Department of Gastroenterology and Hepatology, Mie University, Tsu, Mie, Japan
| | - Matthew D McGeough
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Hal M Hoffman
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Pablo Pelegrin
- Biomedical Research Institute of Murcia, Clinical University Hospital Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Ulrich Laufs
- Universität Leipzig, Klinik und Poliklinik für Kardiologie, Leipzig, Germany
| | - Ariel E Feldstein
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA.
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