New Potential Biomarker Proteins for Alcoholic Liver Disease Identified by a Comparative Proteomics Approach

Exposure to a choline-deficient diet during pregnancy and lactation alters the liver transcriptome profile in offspring of dams with fatty liver

BACKGROUND & AIMS

The developmental origin of health and disease hypothesis shows that early adverse exposures can have lifelong health effects. Thus, the aim of this study was to analyze the impact of choline intake during pregnancy and/or lactation on gene expression profiles in the liver of 24-day-old male rat offspring from dams with non-alcoholic fatty liver disease (NAFLD).

METHODS

Phenotypic characteristic, histological examination and global transcriptome pattern of liver tissue specimens obtained from offspring of dams suffering from fatty liver, provided with proper choline intake during pregnancy and lactation (NN), fed a choline-deficient diet during both periods (DD), deprived of choline only during pregnancy (DN), or only during lactation (ND), was performed. The global gene expression profile was analyzed by using microarray approach (Affymetrix® Rat Gene 2.1 ST Array Strip). The relative expression of selected genes was validated by real-time polymerase chain reaction (qPCR).

RESULTS

The histological examination of rat liver sections indicated alternations typical for fatty liver in all analyzed groups with increased progression among groups deprived of choline. Choline deficiency in the maternal diet was associated with changes in body mass and composition but not with biochemical marker levels, except for the high density lipoprotein fraction of cholesterol (HDL). Enhanced expression of genes involved in oxidative stress, cell proliferation, activation of catabolic processes related to hepatocyte dysfunction and cell membrane composition were simultaneously observed in all choline-deficient groups.

CONCLUSIONS

An adequate amount of choline in the diet of a mother with fatty liver during pregnancy and/or lactation can regulate gene expression in the offspring's liver and contribute to a milder stage of the disease in the progeny. Moreover, proper choline supply during the postpartum period is as crucial as during the prenatal period.

Protective effects of yeast extract against alcohol-induced liver injury in rats

Oxidative stress, inflammatory response, and gut-liver axis dysbiosis have been suggested as the primarily involved in the pathogenesis of alcoholic liver injury. Previous research established that yeast extract (YE) has antioxidant, immune-boosting or microbiota-regulating properties. However, there is currently lack of information regarding the efficacy of YE on alcoholic liver injury. This study seeks to obtain data that will help to address this research gap using a Wistar male rat experimental model. Histologic and biochemical analysis results showed that the groups treated with both low-dose yeast extract (YEL) and high-dose yeast extract (YEH) had lower degrees of alcohol-induced liver injury. The abundance of Peptococcus and Ruminococcus reduced in the low-dose yeast extract (YEL) group, while that of Peptococcus, Romboutsia, Parasutterella, and Faecalibaculum reduced in the high-dose (YEH) group. Furthermore, Spearman analysis showed that the gut microbes were significantly associated with several liver-related indicators. For the analysis of differential metabolites and enriched pathways in the YEL group, the abundance of lysophosphatidylcholine (16:0/0:0) significantly increased, and then the levels of histamine, adenosine and 5' -adenine nucleotide were remarkedly elevated in the YEH group. These findings suggest that both high and low doses of YE can have different protective effects on liver injury in alcoholic liver disease (ALD) rats, in addition to improving gut microbiota disorder. Besides, high-dose YE has been found to be more effective than low-dose YE in metabolic regulation, as well as in dealing with oxidative stress and inflammatory responses.

Parthenolide leads to proteomic differences in thyroid cancer cells and promotes apoptosis

Background

Parthenolide has anti-inflammatory, immunomodulatory and anti-cancer activities. But its effect on thyroid cancer cells is still largely unknown.

Methods

Label-free quantitative proteomics and bioinformatics analysis were used to investigate the differentially expressed proteins and their functions in thyroid cancer treated with parthenolide and control pair. Hoechst 33258 fluorescent staining and Annexin V-FITC/PI double staining flow cytometry were used to detected BCPAP cells apoptosis. Parallel reaction monitoring (PRM) and quantitative real-time PCR were used to verify the expression of apoptosis-related differential proteins and their mRNA.

Results

Sixty up-regulated and 96 down-regulated differentially expressed proteins were identified in parthenolide treated thyroid cancer cells BCPAP compared with control thyroid cancer cells. The proteins were mainly relevant to various biological processes that included metabolic processes, response to extracellular stimulus and interaction with host. The molecular functions of most differentially expressed proteins were associated with binding functions and nucleotidyltransferase activity. According to the Kyoto Encyclopedia of Genes and Genomes, the differentially expressed proteins identified are primarily related to various types of metabolic pathways and DNA replication. In cell experiments in vitro, with the increase of the dose of parthenolide, the number of cells gradually decreased, the apoptosis rate gradually increased. PRM verified that the apoptosis-related proteins HMOX1 and GCLM were up-regulated and IL1B was down-regulated in BCPAP cells treated with parthenolide. The mRNA expressions of HMOX1, GCLM, ITGA6 and CASP8 were up-regulated and HSPA1A was down-regulated by PCR.

Conclusions

Parthenolide may influence the biological behavior of human thyroid cancer cells by affecting the expression of proteins related to cell metabolism and DNA replication. Parthenolide induced significant cellular morphological changes and apoptosis in human thyroid cancer cells, leading to an anti-proliferative effect.

Oxidative Stress-A Key Player in the Course of Alcohol-Related Liver Disease

Oxidative stress is known to be an inseparable factor involved in the presentation of liver disorders. Free radicals interfere with DNA, proteins, and lipids, which are crucial in liver metabolism, changing their expression and biological functions. Additionally, oxidative stress modifies the function of micro-RNAs, impairing the metabolism of hepatocytes. Free radicals have also been proven to influence the function of certain transcriptional factors and to alter the cell cycle. The pathological appearance of alcohol-related liver disease (ALD) constitutes an ideal example of harmful effects due to the redox state. Finally, ethanol-induced toxicity and overproduction of free radicals provoke irreversible changes within liver parenchyma. Understanding the underlying mechanisms associated with the redox state in the course of ALD creates new possibilities of treatment for patients. The future of hepatology may become directly dependent on the effective action against reactive oxygen species. This review summarizes current data on the redox state in the natural history of ALD, highlighting the newest reports on this topic.

Non-invasive diagnosis and biomarkers in alcohol-related liver disease

Even though alcohol-related liver disease (ALD) is a major cause of severe liver disease worldwide, most patients with ALD are diagnosed at the decompensation stage. Liver biopsy is still considered the gold standard for establishing a definite diagnosis and assessing the fibrosis stage of ALD, but it is an invasive procedure, associated with significant morbidity. During the last decade, non-invasive tests have been developed to estimate the severity of liver fibrosis and steatosis. Measurement of liver stiffness by transient elastography has become the most commonly used non-invasive parameter to evaluate fibrosis. In ALD, transient elastography has been demonstrated to have an excellent performance to detect advanced fibrosis and cirrhosis. However, aspartate aminotransferase levels must be considered when interpreting liver stiffness cut-offs. Non-invasive biological tests have also been evaluated to assess liver fibrosis in ALD. The commercially available Enhanced Liver Fibrosis test and FibroTest have comparable performance for the diagnosis of advanced fibrosis in ALD, with studies suggesting that they are better than other biological tests (i.e. FIB-4 and APRI). Although ultrasound is still accepted as an initial screen for fatty liver diagnosis, new methods have recently been developed to detect steatosis. Magnetic resonance spectroscopy and magnetic resonance imaging techniques are highly accurate and reproducible, with superior sensitivities and specificities for detecting histological steatosis than ultrasound. However, low availability and high cost limit the use of magnetic resonance techniques in routine clinical practice. More recently, controlled attenuation parameter was developed as a novel tool to non-invasively assess liver steatosis; performed in combination with transient elastography, it was suggested to be superior to regular ultrasound for detecting steatosis and was shown to have acceptable diagnostic accuracy. New serum biomarkers are under investigation to non-invasively diagnose more severe forms of ALD and to predict prognosis of patients.

Label‑free quantitative proteomics and bioinformatics analyses of alcoholic liver disease in a chronic and binge mouse model

As a significant cause of mortality and morbidity, alcoholic liver disease (ALD) has been widely investigated. However, little is known about the underlying metabolic mechanisms involved in the complicated pathological processes of ALD. The present study used label‑free quantitative proteomics and bioinformatics analyses to investigate the differentially expressed proteins (DEPs) and their functions in the livers of alcohol‑feed (AF) and control pair‑feed (PF) mice. As a result, 87 upregulated DEPs and 133 downregulated DEPs were identified in AF liver tissues compared with PF livers. Gene ontology and Kyoto encyclopedia of genes and genomes bioinformatics analyses demonstrated that the DEPs were significantly enriched in 'protein binding', 'metabolism', 'signal conduction' and 'immune response'. The expression of several core proteins including thyroid hormone receptor interactor 12 (TRIP12), NADH dehydrogenase (ubiquinone)1 α subcomplex, assembly factor 3 (NDUFAF3) and guanine monophosphate synthetase (GMPS) was validated by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) in a larger series of samples. The RT‑qPCR results confirmed that TRIP12, NDUFAF3 and GMPS genes were significantly differentially expressed in between the AF and PF samples. These results extend our understanding of the molecular mechanisms underlying the occurrence and development of ALD. The present study indicated that the majority of DEPs serve vital roles in multiple metabolic pathways and this extends our knowledge of the molecular mechanisms involved in the occurrence and progression of ALD.

Key Events Participating in the Pathogenesis of Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a leading cause of morbidity and mortality worldwide. It ranges from fatty liver to steatohepatitis, fibrosis, cirrhosis and hepatocellular carcinoma. The most prevalent forms of ALD are alcoholic fatty liver, alcoholic hepatitis (AH) and alcoholic cirrhosis, which frequently progress as people continue drinking. ALD refers to a number of symptoms/deficits that contribute to liver injury. These include steatosis, inflammation, fibrosis and cirrhosis, which, when taken together, sequentially or simultaneously lead to significant disease progression. The pathogenesis of ALD, influenced by host and environmental factors, is currently only partially understood. To date, lipopolysaccharide (LPS) translocation from the gut to the portal blood, aging, gender, increased infiltration and activation of neutrophils and bone marrow-derived macrophages along with alcohol plus iron metabolism, with its associated increase in reactive oxygen species (ROS), are all key events contributing to the pathogenesis of ALD. This review aims to introduce the reader to the concept of alcohol-mediated liver damage and the mechanisms driving injury.