Insulin Resistance, Ceramide Accumulation, and Endoplasmic Reticulum Stress in Human Chronic Alcohol-Related Liver Disease

Division of Gastroenterology, Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI 02903, USA.
Oxidative Medicine and Cellular Longevity (Impact Factor: 3.36). 04/2012; 2012(10):479348. DOI: 10.1155/2012/479348
Source: PubMed


Chronic alcohol-related liver disease (ALD) is mediated by insulin resistance, mitochondrial dysfunction, inflammation, oxidative stress, and DNA damage. Recent studies suggest that dysregulated lipid metabolism with accumulation of ceramides, together with ER stress potentiate hepatic insulin resistance and may cause steatohepatitis to progress.
We examined the degree to which hepatic insulin resistance in advanced human ALD is correlated with ER stress, dysregulated lipid metabolism, and ceramide accumulation.
We assessed the integrity of insulin signaling through the Akt pathway and measured proceramide and ER stress gene expression, ER stress signaling proteins, and ceramide profiles in liver tissue.
Chronic ALD was associated with increased expression of insulin, IGF-1, and IGF-2 receptors, impaired signaling through IGF-1R and IRS1, increased expression of multiple proceramide and ER stress genes and proteins, and higher levels of the C14, C16, C18, and C20 ceramide species relative to control.
In human chronic ALD, persistent hepatic insulin resistance is associated with dysregulated lipid metabolism, ceramide accumulation, and striking upregulation of multiple ER stress signaling molecules. Given the role of ceramides as mediators of ER stress and insulin resistance, treatment with ceramide enzyme inhibitors may help reverse or halt progression of chronic ALD.

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    • "First of all, acetaldehyde is a robust ER stress inducer [68]. Additionally, because studies of ceramiderelated ER stress are currently in progress [65] [69], the contribution of excessive FA-induced ER stress to ALD remains obscure. However, past experimental evidence has provided sufficient insight into ER stress caused in the hepatocytes of ALD by excess FA [61-63]. "
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    • "3.3. Effects of ethanol, NDEA, and both exposures on cerebellar neuronal and glial cell protein expression Cerebellar protein homogenates were used to measure Hu (neuronal), myelin-associated glycoprotein 1 (MAG-1; oligodendrocyte), glial fibrillary acidic protein (GFAP; astrocyte), Tau (neuronal cytoskeleton), phospho- Tau (pTau), choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and 4-hydroxy-2-nonenal (HNE; lipid peroxidation adduct) protein expression by duplex ELISAs with results normalized to RPLPO [15]. Two-way ANOVA tests demonstrated no significant effects of ethanol, NDEA, or combined exposures on the expression levels of Hu, Tau, pTau, ChAT, or AChE, or relative levels of Tau phosphorylation (pTau/Tau) (Table 1). "
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    • "Although both chronic (1–2 months) and acute (1–7 days) treatments with high doses of alcohol (i.e., 6.5 g/kg body weight) have been reported to induce ER stress response that contributed to liver injury (Ji, 2012; Galligan et al., 2012; Longato et al., 2012; Ramirez et al., 2013), it is not clear whether long-term (i.e., 1 year) alcohol feeding at moderate doses induces ER stress response and contributes to the observed hepatic tumorigenesis as well. To know that, we examined protein expression of the ER stress markers: GRP94, CHOP, active ATF6 (nATF6), and PDI in the liver of WT versus KO animals of different age groups. "
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