Antje Mohs1, Tobias Otto1, Kai Markus Schneider1, Mona Peltzer1, Mark Boekschoten2, Christian H Holland3, Christian A Hudert4, Laura Kalveram5, Susanna Wiegand5, Julio Saez-Rodriguez6, Thomas Longerich7, Jan G Hengstler8, Christian Trautwein9. 1. Department of Internal Medicine III, University Hospital RWTH Aachen, Aachen, Germany. 2. Department of Agrotechnology and Food Sciences, University Wageningen, Wageningen, the Netherlands. 3. Faculty of Medicine, Institute of Computational Biomedicine, Heidelberg University, Bioquant, Heidelberg, Germany; Faculty of Medicine, Joint Research Centre for Computational Biomedicine (JRC-COMBINE), RWTH Aachen University, Aachen, Germany; Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund (IfADo), Dortmund, Germany. 4. Department of Pediatric Gastroenterology, Charité - Universitätsmedizin Berlin, Germany. 5. Center for Chronically Sick Children, Charité - Universitätsmedizin Berlin, Berlin, Germany. 6. Faculty of Medicine, Institute of Computational Biomedicine, Heidelberg University, Bioquant, Heidelberg, Germany; Faculty of Medicine, Joint Research Centre for Computational Biomedicine (JRC-COMBINE), RWTH Aachen University, Aachen, Germany. 7. Institute of Pathology, University of Heidelberg, Heidelberg, Germany. 8. Systems Toxicology, Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund (IfADo), Dortmund, Germany. 9. Department of Internal Medicine III, University Hospital RWTH Aachen, Aachen, Germany. Electronic address: ctrautwein@ukaachen.de.
Abstract
BACKGROUND & AIMS: In chronic liver diseases, inflammation induces oxidative stress and thus may contribute to the progression of liver injury, fibrosis, and carcinogenesis. The KEAP1/NRF2 axis is a major regulator of cellular redox balance. In the present study, we investigated whether the KEAP1/NRF2 system is involved in liver disease progression in humans and mice. METHODS: The clinical relevance of oxidative stress was investigated by liver RNA sequencing in a well-characterized cohort of patients with non-alcoholic fatty liver disease (n = 63) and correlated with histological and clinical parameters. For functional analysis, hepatocyte-specific Nemo knockout (NEMOΔhepa) mice were crossed with hepatocyte-specific Keap1 knockout (KEAP1Δhepa) mice. RESULTS: Immunohistochemical analysis of human liver sections showed increased oxidative stress and high NRF2 expression in patients with chronic liver disease. RNA sequencing of liver samples in a human pediatric NAFLD cohort revealed a significant increase of NRF2 activation correlating with the grade of inflammation, but not with the grade of steatosis, which could be confirmed in a second adult NASH cohort. In mice, microarray analysis revealed that Keap1 deletion induces NRF2 target genes involved in glutathione metabolism and xenobiotic stress (e.g., Nqo1). Furthermore, deficiency of one of the most important antioxidants, glutathione (GSH), in NEMOΔhepa livers was rescued after deleting Keap1. As a consequence, NEMOΔhepa/KEAP1Δhepa livers showed reduced apoptosis compared to NEMOΔhepa livers as well as a dramatic downregulation of genes involved in cell cycle regulation and DNA replication. Consequently, NEMOΔhepa/KEAP1Δhepa compared to NEMOΔhepa livers displayed decreased fibrogenesis, lower tumor incidence, reduced tumor number, and decreased tumor size. CONCLUSIONS: NRF2 activation in patients with non-alcoholic steatohepatitis correlates with the grade of inflammation, but not steatosis. Functional analysis in mice demonstrated that NRF2 activation in chronic liver disease is protective by ameliorating fibrogenesis, initiation and progression of hepatocellular carcinogenesis. LAY SUMMARY: The KEAP1 (Kelch-like ECH-associated protein-1)/NRF2 (erythroid 2-related factor 2) axis has a major role in regulating cellular redox balance. Herein, we show that NRF2 activity correlates with the grade of inflammation in patients with non-alcoholic steatohepatitis. Functional studies in mice actually show that NRF2 activation, resulting from KEAP1 deletion, protects against fibrosis and cancer.
BACKGROUND & AIMS: In chronic liver diseases, inflammation induces oxidative stress and thus may contribute to the progression of liver injury, fibrosis, and carcinogenesis. The KEAP1/NRF2 axis is a major regulator of cellular redox balance. In the present study, we investigated whether the KEAP1/NRF2 system is involved in liver disease progression in humans and mice. METHODS: The clinical relevance of oxidative stress was investigated by liver RNA sequencing in a well-characterized cohort of patients with non-alcoholic fatty liver disease (n = 63) and correlated with histological and clinical parameters. For functional analysis, hepatocyte-specific Nemo knockout (NEMOΔhepa) mice were crossed with hepatocyte-specific Keap1 knockout (KEAP1Δhepa) mice. RESULTS: Immunohistochemical analysis of human liver sections showed increased oxidative stress and high NRF2 expression in patients with chronic liver disease. RNA sequencing of liver samples in a human pediatric NAFLD cohort revealed a significant increase of NRF2 activation correlating with the grade of inflammation, but not with the grade of steatosis, which could be confirmed in a second adult NASH cohort. In mice, microarray analysis revealed that Keap1 deletion induces NRF2 target genes involved in glutathione metabolism and xenobiotic stress (e.g., Nqo1). Furthermore, deficiency of one of the most important antioxidants, glutathione (GSH), in NEMOΔhepa livers was rescued after deleting Keap1. As a consequence, NEMOΔhepa/KEAP1Δhepa livers showed reduced apoptosis compared to NEMOΔhepa livers as well as a dramatic downregulation of genes involved in cell cycle regulation and DNA replication. Consequently, NEMOΔhepa/KEAP1Δhepa compared to NEMOΔhepa livers displayed decreased fibrogenesis, lower tumor incidence, reduced tumor number, and decreased tumor size. CONCLUSIONS: NRF2 activation in patients with non-alcoholic steatohepatitis correlates with the grade of inflammation, but not steatosis. Functional analysis in mice demonstrated that NRF2 activation in chronic liver disease is protective by ameliorating fibrogenesis, initiation and progression of hepatocellular carcinogenesis. LAY SUMMARY: The KEAP1 (Kelch-like ECH-associated protein-1)/NRF2 (erythroid 2-related factor 2) axis has a major role in regulating cellular redox balance. Herein, we show that NRF2 activity correlates with the grade of inflammation in patients with non-alcoholic steatohepatitis. Functional studies in mice actually show that NRF2 activation, resulting from KEAP1 deletion, protects against fibrosis and cancer.
Authors: Laura Hurtado-Navarro; Diego Angosto-Bazarra; Pablo Pelegrín; Alberto Baroja-Mazo; Santiago Cuevas Journal: Antioxidants (Basel) Date: 2022-04-28
Authors: Daniela Fonseca Abdo Rocha; Pedro Alves Machado-Junior; Ana Beatriz Farias Souza; Thalles de Freitas Castro; Guilherme de Paula Costa; André Talvani; Frank Silva Bezerra; Silvia Dantas Cangussú Journal: Biomed Res Int Date: 2021-11-25 Impact factor: 3.411