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      Alcohol dysregulates miR-148a in hepatocytes through FoxO1, facilitating pyroptosis via TXNIP overexpression

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          Abstract

          Objective

          Alcoholic liver disease (ALD) is a leading cause of death among chronic liver diseases. However, its pathogenesis has not been completely established. MicroRNAs (miRNAs) are key contributors to liver diseases progression. This study investigated hepatocyte-abundant miRNAs dysregulated by ALD, its impact on hepatocyte injury and the underlying basis.

          Design

          Alcoholic hepatitis (AH) human and animal liver samples and hepatocytes were used to assess miR-148a levels. Pre-miR-148a was delivered specifically to hepatocytes in vivo using lentivirus. Immunoblottings, luciferase reporter assays, chromatin immunoprecipitation and immunofluorescence assays were carried out in cell models.

          Results

          The miRNA profile and PCR analyses enabled us to find substantial decrease of miR-148a in the liver of patients with AH. In mice subjected to Lieber-DeCarli alcohol diet or binge alcohol drinking, miR-148a levels were also markedly reduced. In cultured hepatocytes and mouse livers, alcohol exposure inhibited forkhead box protein O1 (FoxO1) expression, which correlated with miR-148a levels and significantly decreased in human AH specimens. FoxO1 was identified as a transcription factor for MIR148A transactivation. MiR-148a directly inhibited thioredoxin-interacting protein (TXNIP) expression. Consequently, treatment of hepatocytes with ethanol resulted in TXNIP overexpression, activating NLRP3 inflammasome and caspase-1-mediated pyroptosis. These events were reversed by miR-148a mimic or TXNIP small-interfering RNA transfection. Hepatocyte-specific delivery of miR-148a to mice abrogated alcohol-induced TXNIP overexpression and inflammasome activation, attenuating liver injury.

          Conclusion

          Alcohol decreases miR-148a expression in hepatocytes through FoxO1, facilitating TXNIP overexpression and NLRP3 inflammasome activation, which induces hepatocyte pyroptosis. Our findings provide information on novel targets for reducing incidence and progression of ALD.

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          Most cited references41

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          NLRP3 inflammasome activation results in hepatocyte pyroptosis, liver inflammation, and fibrosis in mice.

          Inflammasome activation plays a central role in the development of drug-induced and obesity-associated liver disease. However, the sources and mechanisms of inflammasome-mediated liver damage remain poorly understood. Our aim was to investigate the effect of NLRP3 inflammasome activation on the liver using novel mouse models. We generated global and myeloid cell-specific conditional mutant Nlrp3 knock-in mice expressing the D301N Nlrp3 mutation (ortholog of D303N in human NLRP3), resulting in a hyperactive NLRP3. To study the presence and significance of NLRP3-initiated pyroptotic cell death, we separated hepatocytes from nonparenchymal cells and developed a novel flow-cytometry-based (fluorescence-activated cell sorting; FACS) strategy to detect and quantify pyroptosis in vivo based on detection of active caspase 1 (Casp1)- and propidium iodide (PI)-positive cells. Liver inflammation was quantified histologically by FACS and gene expression analysis. Liver fibrosis was assessed by Sirius Red staining and quantitative polymerase chain reaction for markers of hepatic stellate cell (HSC) activation. NLRP3 activation resulted in shortened survival, poor growth, and severe liver inflammation; characterized by neutrophilic infiltration and HSC activation with collagen deposition in the liver. These changes were partially attenuated by treatment with anakinra, an interleukin-1 receptor antagonist. Notably, hepatocytes from global Nlrp3-mutant mice showed marked hepatocyte pyroptotic cell death, with more than a 5-fold increase in active Casp1/PI double-positive cells. Myeloid cell-restricted mutant NLRP3 activation resulted in a less-severe liver phenotype in the absence of detectable pyroptotic hepatocyte cell death. Our data demonstrate that global and, to a lesser extent, myeloid-specific NLRP3 inflammasome activation results in severe liver inflammation and fibrosis while identifying hepatocyte pyroptotic cell death as a novel mechanism of NLRP3-mediated liver damage. © 2014 by the American Association for the Study of Liver Diseases.
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            NLRP3 Gene Silencing Ameliorates Diabetic Cardiomyopathy in a Type 2 Diabetes Rat Model

            Background Nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is associated with metabolic disorder and cell death, which are important triggers in diabetic cardiomyopathy (DCM). We aimed to explore whether NLRP3 inflammasome activation contributes to DCM and the mechanism involved. Methods Type 2 diabetic rat model was induced by high fat diet and low dose streptozotocin. The characteristics of type 2 DCM were evaluated by metabolic tests, echocardiography and histopathology. Gene silencing therapy was used to investigate the role of NLRP3 in the pathogenesis of DCM. High glucose treated H9c2 cardiomyocytes were used to determine the mechanism by which NLRP3 modulated the DCM. The cell death in vitro was detected by TUNEL and EthD-III staining. TXNIP-siRNA and pharmacological inhibitors of ROS and NF-kB were used to explore the mechanism of NLRP3 inflammasome activation. Results Diabetic rats showed severe metabolic disorder, cardiac inflammation, cell death, disorganized ultrastructure, fibrosis and excessive activation of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), pro-caspase-1, activated caspase-1 and mature interleukin-1β (IL-1β). Evidence for pyroptosis was found in vivo, and the caspase-1 dependent pyroptosis was found in vitro. Silencing of NLRP3 in vivo did not attenuate systemic metabolic disturbances. However, NLRP3 gene silencing therapy ameliorated cardiac inflammation, pyroptosis, fibrosis and cardiac function. Silencing of NLRP3 in H9c2 cardiomyocytes suppressed pyroptosis under high glucose. ROS inhibition markedly decreased nuclear factor-kB (NF-kB) phosphorylation, thioredoxin interacting/inhibiting protein (TXNIP), NLRP3 inflammasome, and mature IL-1β in high glucose treated H9c2 cells. Inhibition of NF-kB reduced the activation of NLRP3 inflammasome. TXNIP-siRNA decreased the activation of caspase-1 and IL-1β. Conclusion NLRP3 inflammasome contributed to the development of DCM. NF-κB and TXNIP mediated the ROS-induced caspase-1 and IL-1β activation, which are the effectors of NLRP3 inflammasome. NLRP3 gene silencing may exert a protective effect on DCM.
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              Alcohol, Oxidative Stress, and Free Radical Damage

              Reactive oxygen species (ROS) are small, highly reactive, oxygen-containing molecules that are naturally generated in small amounts during the body’s metabolic reactions and can react with and damage complex cellular molecules such as fats, proteins, or DNA. Alcohol promotes the generation of ROS and/or interferes with the body’s normal defense mechanisms against these compounds through numerous processes, particularly in the liver. For example, alcohol breakdown in the liver results in the formation of molecules whose further metabolism in the cell leads to ROS production. Alcohol also stimulates the activity of enzymes called cytochrome P450s, which contribute to ROS production. Further, alcohol can alter the levels of certain metals in the body, thereby facilitating ROS production. Finally, alcohol reduces the levels of agents that can eliminate ROS (i.e., antioxidants). The resulting state of the cell, known as oxidative stress, can lead to cell injury. ROS production and oxidative stress in liver cells play a central role in the development of alcoholic liver disease.
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                Author and article information

                Journal
                Gut
                Gut
                gutjnl
                gut
                Gut
                BMJ Publishing Group (BMA House, Tavistock Square, London, WC1H 9JR )
                0017-5749
                1468-3288
                April 2019
                23 February 2018
                : 68
                : 4
                : 708-720
                Affiliations
                [1 ] departmentCollege of Pharmacy and Research Institute of Pharmaceutical Sciences , Seoul National University , Seoul, Republic of Korea
                [2 ] departmentDepartment of Biochemistry, School of Medicine , Konkuk University , Seoul, Republic of Korea
                [3 ] departmentLaboratory of Liver Cell Plasticity and Tissue Repair , Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticasy Digestivas (CIBERehd) , Barcelona, Spain
                Author notes
                [Correspondence to ] Dr. Sang Geon Kim, College of Pharmacy, Seoul National University, 1Gwanakro, Seoul 08826, Republic of Korea; sgk@ 123456snu.ac.kr
                Author information
                http://orcid.org/0000-0002-5420-2797
                Article
                gutjnl-2017-315123
                10.1136/gutjnl-2017-315123
                6581021
                29475852
                8f48cfcf-4ba5-4793-885a-7bf96bb67096
                © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2019. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

                This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

                History
                : 23 August 2017
                : 29 January 2018
                : 31 January 2018
                Categories
                Hepatology
                1506
                2312
                Original article
                Custom metadata
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                Gastroenterology & Hepatology
                alcohol-induced injury,inflammation,cell death,cell signalling
                Gastroenterology & Hepatology
                alcohol-induced injury, inflammation, cell death, cell signalling

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