부산대학교 도서관

Keywords: EGFR; transgenic mouse; DDC diet; cholestasis; liver disease; regeneration; inflammation; ductular reaction; hepatic progenitor cell Abstract Despite the well-known hepatoprotective role of the epidermal growth factor receptor (EGFR) pathway upon acute damage, its specific actions during chronic liver disease, particularly cholestatic injury, remain ambiguous and unresolved. Here, we analyzed the consequences of inactivating EGFR signaling in the liver on the regenerative response following cholestatic injury. For that, transgenic mice overexpressing a dominant negative mutant human EGFR lacking tyrosine kinase activity (ÎEGFR) in albumin-positive cells were submitted to liver damage induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC), an experimental model resembling human primary sclerosing cholangitis. Our results show an early activation of EGFR after 1-2days of a DDC-supplemented diet, followed by a signaling switch-off. Furthermore, ÎEGFR mice showed less liver damage and a more efficient regeneration following DDC injury. Analysis of the mechanisms driving this effect revealed an enhanced activation of mitogenic/survival signals, AKT and ERK1/2-MAPKs, and changes in cell turnover consistent with a quicker resolution of damage in response to DDC. These changes were concomitant with profound differences in the profile of intrahepatic immune cells, consisting of a shift in the M1/M2 balance towards M2 polarity, and the Cd4/Cd8 ratio in favor of Cd4 lymphocytes, overall supporting an immune cell switch into a pro-restorative phenotype. Interestingly, ÎEGFR livers also displayed an amplified ductular reaction, with increased expression of EPCAM and an increased number of CK19-positive ductular structures in portal areas, demonstrating an overexpansion of ductular progenitor cells. In summary, our work supports the notion that hepatocyte-specific EGFR activity acts as a key player in the crosstalk between parenchymal and non-parenchymal hepatic cells, promoting the pro-inflammatory response activated during cholestatic injury and therefore contributing to the pathogenesis of cholestatic liver disease. © 2022 The Pathological Society of Great Britain and Ireland. Article Note: No conflicts of interest were declared. CAPTION(S): Supplementary materials and methods Figure S1. Expression of EGFR family ligands in the livers of mice fed the DDC diet Figure S2. Expression of mRNAs for ligands and receptors of the EGFR family in the livers of patients with primary sclerosing cholangitis (PSC) and primary biliary cirrhosis (PBC) Figure S3. Analysis of lysyl oxidase-like 1 and 2 mRNA expression in ÎEGFR livers of mice fed the DDC diet Figure S4. Analysis of caspase-3 activation in ÎEGFR livers of mice fed the DDC diet Figure S5. Representative H&E images for visualization of inflammatory cells in the portal areas of WT and ÎEGFR livers of mice fed the DDC diet Figure S6. Analysis of the inflammatory response in ÎEGFR livers of mice fed the DDC diet Figure S7. Analysis of the ductular reaction in the livers of mice fed the DDC diet Figure S8. Analysis of the expression of the ÎEGFR transgene and EGFR signaling activation in oval cells Table S1. Primer sequences used in quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) (referred to in Supplementary materials and methods) Table S2. Analysis of ductal proliferation in the livers of mice fed the DDC diet Byline: Nerea Lazcanoiturburu, Juan García-Sáez, Carlos González-Corralejo, Cesáreo Roncero, Julián Sanz, Carlos Martín-Rodríguez, M Pilar Valdecantos, Adoración Martínez-Palacián, Laura Almalé, Paloma Bragado, Silvia Calero-Pérez, Almudena Fernández, María García-Bravo, Carmen Guerra, Lluis Montoliu, José Carlos Segovia, Ángela M Valverde, Isabel Fabregat, Blanca Herrera, Aránzazu Sánchez