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      Hepatic protein-tyrosine phosphatase 1B disruption and pharmacological inhibition attenuate ethanol-induced oxidative stress and ameliorate alcoholic liver disease in mice

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          Abstract

          Alcoholic liver disease (ALD) is a major health problem and a significant cause of liver-related death. Currently, the mainstay for ALD therapy is alcohol abstinence highlighting the need to develop pharmacotherapeutic approaches. Protein-tyrosine phosphatase 1B (PTP1B) is an established regulator of hepatic functions, but its role in ALD is mostly unexplored. In this study, we used mice with liver-specific PTP1B disruption as well as pharmacological inhibition to investigate the in vivo function of this phosphatase in ALD. We report upregulation of hepatic PTP1B in the chronic plus binge mouse model and, importantly, in liver biopsies of alcoholic hepatitis patients. Also, mice with hepatic PTP1B disruption attenuated ethanol-induced injury, inflammation, and steatosis compared with ethanol-fed control animals. Moreover, PTP1B deficiency was associated with decreased ethanol-induced oxidative stress in vivo and ex vivo. Further, pharmacological modulation of oxidative balance in hepatocytes identified diminished oxidative stress as a contributor to the salutary effects of PTP1B deficiency. Notably, PTP1B pharmacological inhibition elicited beneficial effects and mitigated hepatic injury, inflammation, and steatosis caused by ethanol feeding. In summary, these findings causally link hepatic PTP1B and ALD and define a potential therapeutic target for the management of this disease.

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          Highlights

          • Hepatic PTP1B expression is elevated in a mouse model of ALD and AH patients.

          • Liver-specific PTP1B disruption ameliorated ALD in mice.

          • PTP1B deficiency was associated with decreased ethanol-induced oxidative stress.

          • PTP1B pharmacological inhibition attenuated alcohol-induced hepatic injury in mice.

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          Most cited references60

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          Mouse model of chronic and binge ethanol feeding (the NIAAA model).

          Chronic alcohol consumption is a leading cause of chronic liver disease worldwide, leading to cirrhosis and hepatocellular carcinoma. Currently, the most widely used model for alcoholic liver injury is ad libitum feeding with the Lieber-DeCarli liquid diet containing ethanol for 4-6 weeks; however, this model, without the addition of a secondary insult, only induces mild steatosis, slight elevation of serum alanine transaminase (ALT) and little or no inflammation. Here we describe a simple mouse model of alcoholic liver injury by chronic ethanol feeding (10-d ad libitum oral feeding with the Lieber-DeCarli ethanol liquid diet) plus a single binge ethanol feeding. This protocol for chronic-plus-single-binge ethanol feeding synergistically induces liver injury, inflammation and fatty liver, which mimics acute-on-chronic alcoholic liver injury in patients. This feeding protocol can also be extended to chronic feeding for longer periods of time up to 8 weeks plus single or multiple binges. Chronic-binge ethanol feeding leads to high blood alcohol levels; thus, this simple model will be very useful for the study of alcoholic liver disease (ALD) and of other organs damaged by alcohol consumption.
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            CYP2E1 and oxidative liver injury by alcohol.

            Ethanol-induced oxidative stress seems to play a major role in mechanisms by which ethanol causes liver injury. Many pathways have been suggested to contribute to the ability of ethanol to induce a state of oxidative stress. One central pathway seems to be the induction of cytochrome P450 2E1 (CYP2E1) by ethanol. CYP2E1 metabolizes and activates many toxicological substrates, including ethanol, to more reactive, toxic products. Levels of CYP2E1 are elevated under a variety of physiological and pathophysiological conditions and after acute and chronic alcohol treatment. CYP2E1 is also an effective generator of reactive oxygen species such as the superoxide anion radical and hydrogen peroxide and, in the presence of iron catalysts, produces powerful oxidants such as the hydroxyl radical. This review article summarizes some of the biochemical and toxicological properties of CYP2E1 and briefly describes the use of cell lines developed to constitutively express CYP2E1 and CYP2E1 knockout mice in assessing the actions of CYP2E1. Possible therapeutic implications for treatment of alcoholic liver injury by inhibition of CYP2E1 or CYP2E1-dependent oxidative stress will be discussed, followed by some future directions which may help us to understand the actions of CYP2E1 and its role in alcoholic liver injury.
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              Reversible inactivation of protein-tyrosine phosphatase 1B in A431 cells stimulated with epidermal growth factor.

              Stimulation of various cells with growth factors results in a transient increase in the intracellular concentration of H2O2 that is required for growth factor-induced protein tyrosine phosphorylation. The effect of H2O2 produced in response to epidermal growth factor (EGF) on the activity of protein-tyrosine phosphatase 1B (PTP1B) was investigated in A431 human epidermoid carcinoma cells. H2O2 inactivated recombinant PTP1B in vitro by oxidizing its catalytic site cysteine, most likely to sulfenic acid. The oxidized enzyme was reactivated more effectively by thioredoxin than by glutaredoxin or glutathione at their physiological concentrations. Oxidation by H2O2 prevented modification of the catalytic cysteine of PTP1B by iodoacetic acid, suggesting that it should be possible to monitor the oxidation state of PTP1B in cells by measuring the incorporation of radioactivity into the enzyme after lysis of the cells in the presence of radiolabeled iodoacetic acid. The amount of such radioactivity associated with PTP1B immunoprecipitated from A431 cells that had been stimulated with EGF for 10 min was 27% less than that associated with PTP1B from unstimulated cells. The amount of iodoacetic acid-derived radioactivity associated with PTP1B reached a minimum 10 min after stimulation of cells with EGF and returned to base line values by 40 min, suggesting that the oxidation of PTP1B is reversible in cells. These results indicate that the activation of a receptor tyrosine kinase by binding of the corresponding growth factor may not be sufficient to increase the steady state level of protein tyrosine phosphorylation in cells and that concurrent inhibition of protein-tyrosine phosphatases by H2O2 might also be required.
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                Author and article information

                Contributors
                Journal
                Redox Biol
                Redox Biol
                Redox Biology
                Elsevier
                2213-2317
                24 July 2020
                September 2020
                24 July 2020
                : 36
                : 101658
                Affiliations
                [a ]Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA, 95616, USA
                [b ]Department of Inflammation and Immunity, Cleveland Clinic Foundation, Cleveland, OH, 44195, USA
                [c ]Comprehensive Cancer Center, University of California Davis, Sacramento, CA, 95817, USA
                [d ]Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, University of California Davis, Sacramento, CA, 95817, USA
                Author notes
                []Corresponding author. The University of California Davis, Department of Nutrition, 3135 Meyer Hall, Davis, CA 95616, USA. mfhsu@ 123456ucdavis.edu
                [∗∗ ]Corresponding author. The University of California Davis, Department of Nutrition, 3135 Meyer Hall, Davis, CA 95616, USA. fghaj@ 123456ucdavis.edu
                [1]

                Current address: University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA.

                Article
                S2213-2317(20)30863-6 101658
                10.1016/j.redox.2020.101658
                7408361
                32769011
                84253ddc-d5cd-40fe-bc2e-f66436eadc7f
                © 2020 The Authors

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

                History
                : 15 May 2020
                : 29 June 2020
                : 21 July 2020
                Categories
                Research Paper

                alcoholic liver disease,hepatocyte,protein-tyrosine phosphatase 1b,oxidative stress,inflammation,steatosis

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