Model Of Alcoholic Steatohepatitis Research Articles

RNA Binding Protein ZFP36L1 Regulates Alcoholic Steatohepatitis in Mice

Zinc finger protein 36 like 1 (ZFP36L1) regulates mRNA levels by binding to AU‐rich elements (ARE’s) on the 3′untranslated regions (3′UTR) of specific mRNAs and enhancing their turnover. While the biochemical function of ZFP36L1 is somewhat understood, its physiological and pathological functions remain unknown. Here, we sought to investigate the roles of ZFP36L1 in liver physiology and pathology by generating liver‐specific deletion of ZFP36L1 (Zfp36l1LKO) using Cre‐loxP approach and subjecting them to alcoholic steatohepatitis. Liver‐specific loss of ZFP36L1 did not result in any aberrant phenotype in mice. However, Zfp36l1LKO mice were significantly protected from developing alcohol‐induced hepatic steatosis in Lieber‐DeCarli liquid diet‐induced model of alcoholic steatohepatitis. Serum levels of ALT did not significantly increase in Zfp36l1LKO mice upon alcohol consumption while serum levels of ALT were significantly upregulated in wild type (WT) alcohol‐treated mice. Transcriptomic analysis showed less than 170 differentially expressed transcripts in alcohol‐treated Zfp36l1LKO mice compared to greater than 500 differentially expressed transcripts in alcohol‐treated WT mice. Mechanistically, the levels of fibroblast growth factor 21 (Fgf21) mRNA were significantly increased and lipoprotein lipase (Lpl) mRNA were significantly reduced in the livers of alcohol‐treated Zfp36l1LKO mice compared to alcohol‐treated WT group. We further found evidence that Fgf21 mRNA is a direct target of ZFP36L1. FGF21 is a metabolic regulator of glucose and lipid metabolism and has been previously found to be significantly induced upon alcohol consumption and protect against alcohol‐induced liver injury. In summary, our results demonstrate that FGF21 is post‐transcriptionally regulated by ZFP36L1 in alcoholic liver injury. Modulation of levels of ZFP36L1 may be beneficial in the prevention or treatment of human alcoholic liver disease.Support or Funding InformationStart Up Funds, LSUSVM

697 – Intestinal Permeability is an Important Factor in the Development of Alcoholic Liver Disease in a Chronic and Binge Mouse Model of Alcoholic Steatohepatitis

697 – Intestinal Permeability is an Important Factor in the Development of Alcoholic Liver Disease in a Chronic and Binge Mouse Model of Alcoholic Steatohepatitis

Cranberry (Vaccinium macrocarpon) peel polyphenol-rich extract attenuates rat liver mitochondria impairments in alcoholic steatohepatitis in vivo and after oxidative treatment in vitro

Abstract Alcoholic steatohepatitis is an important medical problem but its effective therapies are still not available. Plant polyphenols are widely used for prevention of toxic liver damages. The aim of the study was to evaluate the hepatoprotective mechanism(s) of a cranberry peel polyphenol-rich extract, focusing on the effects of the polyphenols on the mitochondrial function. The main components of cranberry peel phenolic compounds were anthocyanins, flavan-3-ols, procyanidins, flavonols, phenolic acids, as was detected using UHPLC-ESI-QTOF-MS. The treatment of rats receiving ethanol (4 g/kg bw, 8 weeks) with cranberry polyphenols (daily, 4 mg/kg bw) partially prevented alcoholic liver damage, ameliorating steatosis and inflammatory signs in the liver, decreasing serum and liver triglyceride contents, ALT and AST activities, as well as diminishing TNFα and TGFβ levels in serum. The polyphenols inhibited Ca2+ - induced mitochondrial permeability transition, free radical generation in mitochondria during intoxication. The polyphenols (25 µg/ml) prevented mitochondrial oxidative impairments in vitro. In conclusion, the cranberry peel polyphenols with antioxidant properties exerted a hepatoprotective and anti-inflammatory effects in the model of alcoholic steatohepatitis via prevention of liver mitochondria dysfunction.

Activation of Fas/FasL and its downstream signaling pathway promotes development of alcoholic steatohepatitis and liver fibrosis in mice

To explore the role and mechanism of the Fas/Fas ligand (FasL) system and its downstream signaling pathway related to the progression of alcoholic steatohepatitis and liver fibrosis. Eighteen C57BL/6J mice were randomly divided into three groups: controls; alcoholic steatohepatitis model, given four-weeks of a 4% ethanol-containing Lieber-DeCarli liquid diet; alcoholic steatohepatitis and liver fibrosis model, given the four-week alcohol diet followed by twice weekly intraperitoneal injections of carbon tetrachloride (5% olive oil solution; 2 mL/kg dose) during the fifth to eighth weeks. Mice in the model groups were sacrificed at the end of week 4 and 8, respectively, along with control mice for comparative analyses. Liver tissue sections were evaluated for hepatocellular apoptosis by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. The mRNA expression of Fas, FasL, cysteine aspartate-specific proteases 3 (caspase 3), and cytochrome P450 2E1 (CYP 2E1) in liver tissues was detected by reverse transcription (RT)-PCR, visualized by ethidium bromide staining, and normalized to the gray-value of GAPDH expression. The protein expression of Fas and caspase 3 were detected by western blotting (b-actin normalized), and of FasL and CYP 2E1 by immunohistochemistry staining. Intergroup differences and statistical significance were evaluated by single factor analysis of variance and the least squares difference-t test or the Kruskal-Wallis H test and the Mann-Whitney U test. The number of apoptotic cells in the liver sections was significantly higher in both model groups with alcoholic steatohepatitis (vs. controls) and the amount in the alcoholic steatohepatitis plus liver fibrosis model was significantly higher than that in the model with only alcoholic steatohepatitis. In addition, activation of Fas, FasL and its downstream signaling pathway showed an increasing trend with extent of liver injury. The hepatic mRNA (by RT-PCR) and protein (by western blotting) normalized expression levels in the controls, alcoholic steatohepatitis models, and alcoholic steatohepatitis plus liver fibrosis models were, respectively: Fas mRNA: 0.50+/-0.05, 0.61+/-0.10, 0.76+/-0.03 (H=12.137, P less than 0.05), protein: 0.52+/-0.14, 0.86+/-0.10, 0.99+/-0.09 (F=12.758, P less than 0.01); FasL mRNA: 0.31+/-0.03, 0.53+/-0.02, 1.02+/-0.04 (F=153.260, P less than 0.01); caspase 3 mRNA: 0.86+/-0.11, 0.85+/-0.05, 1.33+/-0.16 (F=8.740, P less than 0.01), protein: 0.40+/-0.03, 0.69+/-0.06, 1.02+/-0.10 (F=90.785, P less than 0.01); CYP 2E1 mRNA: 0.72+/-0.14, 1.00+/-0.15, 1.30+/-0.20 (H=4.713, P less than 0.01). The changes in hepatic FasL and CYP 2E1 expression detected by immunohistochemistry were consistent with the mRNA expression. Activation of Fas/FasL and its downstream signaling pathway, which induces hepatocellular apoptosis, contributes to the development of alcoholic steatohepatitis and liver fibrosis.

Role of osteopontin in regulating hepatic inflammatory responses and toxic liver injury

Osteopontin (OPN) produced by cells of the immune system, epithelial tissue, smooth muscle cells, osteoblasts and tumor cells has been implicated in various pathophysiological functions such as cell binding, spreading and migration, and tumor metastasis. OPN is known to bind to integrins expressed on macrophages through the arginine-glycine-aspartic acid (RGD) motif and promote migration of cells resulting in granuloma. In the liver, it has been reported that hepatic Kupffer cells secrete OPN facilitating macrophage infiltration in necrotic areas following carbon tetrachloride liver toxicity. Recent work has underlined the importance of OPN as a pivotal cytokine/chemokine in the generated hepatic neutrophil response during early phase alcoholic liver injury. Increased hepatobiliary OPN expression correlated well with higher neutrophil infiltration in a rat model of alcoholic steatohepatitis. In the same model of alcoholic steatohepatitis, higher hepatic expression of OPN in females was attributed to the higher neutrophil infiltration and consequent higher female sensitivity to liver damage. OPN as a potential biomarker for inflammatory liver disease has also been recently assessed. This review will focus on studies demonstrating the role of OPN in mediating hepatic inflammation (neutrophils, monocytes/macrophages and lymphocytes) and the ensuing liver toxicity.

Role of osteopontin in regulating hepatic inflammatory responses and toxic liver injury

Osteopontin (OPN) produced by cells of the immune system, epithelial tissue, smooth muscle cells, osteoblasts and tumor cells has been implicated in various pathophysiological functions such as cell binding, spreading and migration, and tumor metastasis. OPN is known to bind to integrins expressed on macrophages through the arginine-glycine-aspartic acid (RGD) motif and promote migration of cells resulting in granuloma. In the liver, it has been reported that hepatic Kupffer cells secrete OPN facilitating macrophage infiltration in necrotic areas following carbon tetrachloride liver toxicity. Recent work has underlined the importance of OPN as a pivotal cytokine/chemokine in the generated hepatic neutrophil response during early phase alcoholic liver injury. Increased hepatobiliary OPN expression correlated well with higher neutrophil infiltration in a rat model of alcoholic steatohepatitis. In the same model of alcoholic steatohepatitis, higher hepatic expression of OPN in females was attributed to the higher neutrophil infiltration and consequent higher female sensitivity to liver damage. OPN as a potential biomarker for inflammatory liver disease has also been recently assessed. This review will focus on studies demonstrating the role of OPN in mediating hepatic inflammation (neutrophils, monocytes/macrophages and lymphocytes) and the ensuing liver toxicity.