School of Medicine and Health Sciences Poster Presentations
Dietary Spermidine protects against Ethanol and Lipopolysaccharide induced Hepatic Oxidative Stress and Fibrosis
Poster Number
12
Document Type
Poster
Publication Date
3-2016
Abstract
Alcohol liver disease (ALD) is a leading cause of death worldwide. The well-accepted two-hit model of ethanol and endotoxin, lipopolysaccharide (LPS) for ALD mimics the human disease by combining ethanol mediated oxidative stress caused by the metabolites of ethanol or endotoxin mediated increase in cytokines resulting in a deleterious positive feedback loop that propagates inflammation and fibrosis. In the first hit, ethanol is oxidized to acetaldehyde by alcohol dehydrogenase and cytochrome P4502E1 in hepatocytes, generating reactive oxygen species (ROS) within the cells. The second hit perpetuates liver injury and fibrosis as a result of endotoxin-induced activation of Kupffer cells resulting in oxidative stress and the activation of hepatic stellate cells (HSC), causing the up regulation of fibrogenic markers, platelet derived growth factor β-receptor (PDGFβR), α-smooth muscle actin (αSMA), collagen I (Col1) and fibronectin; and epigenetic repressor gene, methyl-CpG binding protein 2 (MeCP2). In contrast, the adipogenic gene, peroxisome proliferator-activated receptor γ (PPARγ) is suppressed leading to the transdifferentiation of HSC from quiescent to activated myofibroblastic phenotype, resulting in fibrosis. Spermidine, a naturally occurring polyamine found in soybean, mushrooms and whole grains is known for anti-aging properties and resistance to stress. In this study, the role of dietary spermidine in ethanol-LPS induced hepatic oxidative stress and fibrosis was investigated. Ethanol-LPS mediated liver injury was induced in C57BL/6 mice using chronic 5% ethanol fed in a liquid diet for 4 weeks plus a single dose of ethanol (5g/kg body wt, gavage) and LPS (2mg/kg body wt, ip), 6h prior to the experiment. Spermidine (5mg/kg body wt) was added to the liquid diet for 4 weeks. Oxidative stress was determined using ROS and glutathione (GSH) fluorescent assays and expression of superoxide dismutase (SOD). The above mentioned genes and their products were measured using RT-PCR and Western blot, respectively. The extent of fibrosis was determined by measuring the hydroxyproline content for collagen and Sirius Red stain. Spermidine protected against ethanol-LPS induced oxidative stress by decreasing the levels of ROS and the expression of SOD, and increasing the levels of the GSH. It also prevented the activation of HSC by suppressing the up regulated MeCP2, that coordinately reversed the down regulated PPARγ and the up regulated fibrogenic genes (αSMA, PDGFβR, Col1 and fibronectin). Spermidine also prevented fibrosis by decreasing hydroxyproline content and collagen fibers. These data suggest that spermidine may have potential as an anti-oxidant and anti-fibrotic agent for the prevention/treatment of ALD.
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Open Access
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Dietary Spermidine protects against Ethanol and Lipopolysaccharide induced Hepatic Oxidative Stress and Fibrosis
Alcohol liver disease (ALD) is a leading cause of death worldwide. The well-accepted two-hit model of ethanol and endotoxin, lipopolysaccharide (LPS) for ALD mimics the human disease by combining ethanol mediated oxidative stress caused by the metabolites of ethanol or endotoxin mediated increase in cytokines resulting in a deleterious positive feedback loop that propagates inflammation and fibrosis. In the first hit, ethanol is oxidized to acetaldehyde by alcohol dehydrogenase and cytochrome P4502E1 in hepatocytes, generating reactive oxygen species (ROS) within the cells. The second hit perpetuates liver injury and fibrosis as a result of endotoxin-induced activation of Kupffer cells resulting in oxidative stress and the activation of hepatic stellate cells (HSC), causing the up regulation of fibrogenic markers, platelet derived growth factor β-receptor (PDGFβR), α-smooth muscle actin (αSMA), collagen I (Col1) and fibronectin; and epigenetic repressor gene, methyl-CpG binding protein 2 (MeCP2). In contrast, the adipogenic gene, peroxisome proliferator-activated receptor γ (PPARγ) is suppressed leading to the transdifferentiation of HSC from quiescent to activated myofibroblastic phenotype, resulting in fibrosis. Spermidine, a naturally occurring polyamine found in soybean, mushrooms and whole grains is known for anti-aging properties and resistance to stress. In this study, the role of dietary spermidine in ethanol-LPS induced hepatic oxidative stress and fibrosis was investigated. Ethanol-LPS mediated liver injury was induced in C57BL/6 mice using chronic 5% ethanol fed in a liquid diet for 4 weeks plus a single dose of ethanol (5g/kg body wt, gavage) and LPS (2mg/kg body wt, ip), 6h prior to the experiment. Spermidine (5mg/kg body wt) was added to the liquid diet for 4 weeks. Oxidative stress was determined using ROS and glutathione (GSH) fluorescent assays and expression of superoxide dismutase (SOD). The above mentioned genes and their products were measured using RT-PCR and Western blot, respectively. The extent of fibrosis was determined by measuring the hydroxyproline content for collagen and Sirius Red stain. Spermidine protected against ethanol-LPS induced oxidative stress by decreasing the levels of ROS and the expression of SOD, and increasing the levels of the GSH. It also prevented the activation of HSC by suppressing the up regulated MeCP2, that coordinately reversed the down regulated PPARγ and the up regulated fibrogenic genes (αSMA, PDGFβR, Col1 and fibronectin). Spermidine also prevented fibrosis by decreasing hydroxyproline content and collagen fibers. These data suggest that spermidine may have potential as an anti-oxidant and anti-fibrotic agent for the prevention/treatment of ALD.
Comments
Presented at: GW Research Days 2016