Jalan, R;
De Chiara, F;
Balasubramaniyan, V;
Andreola, F;
Khetan, V;
Malago, M;
Pinzani, M;
... Rombouts, K; + view all
(2016)
Ammonia produces pathological changes in human hepatic stellate cells and is a target for therapy of portal hypertension.
Journal of Hepatology
, 64
(4)
pp. 823-833.
10.1016/j.jhep.2015.11.019.
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Abstract
BACKGROUND AND AIMS: Hepatic stellate cells (HSCs) are vital to hepatocellular function and the liver response to injury. They share a phenotypic homology with astrocytes that are central in the pathogenesis of hepatic encephalopathy, a condition in which hyperammonemia plays a pathogenic role. This study tested the hypothesis that ammonia modulates human HSC activation in vitro and in vivo, and evaluated whether ammonia lowering, by using l-ornithine phenylacetate (OP), modifies HSC activation in vivo and reduces portal pressure in a bile duct ligation (BDL) model. METHODS: Primary human HSCs were isolated and cultured. Proliferation (BrdU), metabolic activity (MTS), morphology (transmission electron, light and immunofluorescence microscopy), HSC activation markers, ability to contract, changes in oxidative status (ROS) and endoplasmic reticulum (ER) were evaluated to identify effects of ammonia challenge (50 μM, 100 μM, 300 μM) over 24–72 h. Changes in plasma ammonia levels, markers of HSC activation, portal pressure and hepatic eNOS activity were quantified in hyperammonemic BDL animals, and after OP treatment. RESULTS: Pathophysiological ammonia concentrations caused significant and reversible changes in cell proliferation, metabolic activity and activation markers of hHSC in vitro. Ammonia also induced significant alterations in cellular morphology, characterised by cytoplasmic vacuolisation, ER enlargement, ROS production, hHSC contraction and changes in pro-inflammatory gene expression together with HSC-related activation markers such as α-SMA, myosin IIa, IIb, and PDGF-Rβ. Treatment with OP significantly reduced plasma ammonia (BDL 199.1 μmol/L ± 43.65 vs. BDL + OP 149.27 μmol/L ± 51.1, p <0.05) and portal pressure (BDL 14 ± 0.6 vs. BDL + OP 11 ± 0.3 mmHg, p <0.01), which was associated with increased eNOS activity and abrogation of HSC activation markers. CONCLUSIONS: The results show for the first time that ammonia produces deleterious morphological and functional effects on HSCs in vitro. Targeting ammonia with the ammonia lowering drug OP reduces portal pressure and deactivates hHSC in vivo, highlighting the opportunity for evaluating ammonia lowering as a potential therapy in cirrhotic patients with portal hypertension.
| Type: | Article |
|---|---|
| Title: | Ammonia produces pathological changes in human hepatic stellate cells and is a target for therapy of portal hypertension |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.jhep.2015.11.019 |
| Publisher version: | http://dx.doi.org/10.1016/j.jhep.2015.11.019 |
| Language: | English |
| Additional information: | Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ |
| Keywords: | Science & Technology, Life Sciences & Biomedicine, Gastroenterology & Hepatology, Human hepatic stellate cells, (hHSC), Ammonia, Glutamine synthetase, (GS), Ornithine phenylacetate, (OP), Bile duct ligation, (BDL), Endoplasmic reticulum stress, (ER), Oxidative stress, Hepatic encephalopathy, (HE), P38 Map Kinase, Liver Fibrosis, Glutamine-synthetase, Tyrosine Nitration, Cirrhotic Rats, L-Ornithine, In-Vivo, Brain, Encephalopathy, Protein |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Inst for Liver and Digestive Hlth |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1536356 |
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