Alejandra Hernández1, Daniela Reyes2, Yana Geng3, Juan Pablo Arab4, Daniel Cabrera5, Rolando Sepulveda2, Nancy Solis2, Manon Buist-Homan3, Marco Arrese4, Han Moshage6. 1. Departamento de Gastroenterología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. 2. Departamento de Gastroenterología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. 3. Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. 4. Departamento de Gastroenterología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile, Santiago, Chile. 5. Departamento de Gastroenterología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile; Facultad de Ciencias Médicas, Universidad Bernardo O Higgins, Santiago, Chile; Departamento de Ciencias Químicas y Biológicas, Facultad de Salud, Universidad Bernardo O Higgins, Santiago, Chile. 6. Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. Electronic address: a.j.moshage@umcg.nl.
Abstract
BACKGROUND: The transition from steatosis to non-alcoholic steatohepatitis (NASH) is a key issue in non-alcoholic fatty liver disease (NAFLD). Observations in patients with obstructive sleep apnea syndrome (OSAS) suggest that hypoxia contributes to progression to NASH and liver fibrosis, and the release of extracellular vesicles (EVs) by injured hepatocytes has been implicated in NAFLD progression. AIM: To evaluate the effects of hypoxia on hepatic pro-fibrotic response and EV release in experimental NAFLD and to assess cellular crosstalk between hepatocytes and human hepatic stellate cells (LX-2). METHODS: HepG2 cells were treated with fatty acids and subjected to chemically induced hypoxia using the hypoxia-inducible factor 1 alpha (HIF-1α) stabilizer cobalt chloride (CoCl2). Lipid droplets, oxidative stress, apoptosis and pro-inflammatory and pro-fibrotic-associated genes were assessed. EVs were isolated by ultracentrifugation. LX-2 cells were treated with EVs from hepatocytes. The CDAA-fed mouse model was used to assess the effects of intermittent hypoxia (IH) in experimental NASH. RESULTS: Chemical hypoxia increased steatosis, oxidative stress, apoptosis and pro-inflammatory and pro-fibrotic gene expressions in fat-laden HepG2 cells. Chemical hypoxia also increased the release of EVs from HepG2 cells. Treatment of LX2 cells with EVs from fat-laden HepG2 cells undergoing chemical hypoxia increased expression pro-fibrotic markers. CDAA-fed animals exposed to IH exhibited increased portal inflammation and fibrosis that correlated with an increase in circulating EVs. CONCLUSION: Chemical hypoxia promotes hepatocellular damage and pro-inflammatory and pro-fibrotic signaling in steatotic hepatocytes both in vitro and in vivo. EVs from fat-laden hepatocytes undergoing chemical hypoxia evoke pro-fibrotic responses in LX-2 cells.
BACKGROUND: The transition from steatosis to non-alcoholic steatohepatitis (NASH) is a key issue in non-alcoholic fatty liver disease (NAFLD). Observations in patients with obstructive sleep apnea syndrome (OSAS) suggest that hypoxia contributes to progression to NASH and liver fibrosis, and the release of extracellular vesicles (EVs) by injured hepatocytes has been implicated in NAFLD progression. AIM: To evaluate the effects of hypoxia on hepatic pro-fibrotic response and EV release in experimental NAFLD and to assess cellular crosstalk between hepatocytes and human hepatic stellate cells (LX-2). METHODS:HepG2 cells were treated with fatty acids and subjected to chemically induced hypoxia using the hypoxia-inducible factor 1 alpha (HIF-1α) stabilizer cobalt chloride (CoCl2). Lipid droplets, oxidative stress, apoptosis and pro-inflammatory and pro-fibrotic-associated genes were assessed. EVs were isolated by ultracentrifugation. LX-2 cells were treated with EVs from hepatocytes. The CDAA-fed mouse model was used to assess the effects of intermittent hypoxia (IH) in experimental NASH. RESULTS: Chemical hypoxia increased steatosis, oxidative stress, apoptosis and pro-inflammatory and pro-fibrotic gene expressions in fat-laden HepG2 cells. Chemical hypoxia also increased the release of EVs from HepG2 cells. Treatment of LX2 cells with EVs from fat-laden HepG2 cells undergoing chemical hypoxia increased expression pro-fibrotic markers. CDAA-fed animals exposed to IH exhibited increased portal inflammation and fibrosis that correlated with an increase in circulating EVs. CONCLUSION: Chemical hypoxia promotes hepatocellular damage and pro-inflammatory and pro-fibrotic signaling in steatotic hepatocytes both in vitro and in vivo. EVs from fat-laden hepatocytes undergoing chemical hypoxia evoke pro-fibrotic responses in LX-2 cells.
Authors: Liting Zhang; Jing Gao; Dan Zhou; Xiaojun Wang; Junfeng Li; Juan Wang; Hong Chen; Xiaodong Xie; Tuo Chen Journal: Ann Transl Med Date: 2021-09
Authors: Julio Plaza-Díaz; Patricio Solís-Urra; Fernando Rodríguez-Rodríguez; Jorge Olivares-Arancibia; Miguel Navarro-Oliveros; Francisco Abadía-Molina; Ana I Álvarez-Mercado Journal: Int J Mol Sci Date: 2020-11-07 Impact factor: 5.923