Changes of the Hepatic Proteome in Hepatitis B-Infected Mouse Model at Early Stages of Fibrosis

Proteomic and transcriptomic studies of HBV-associated liver fibrosis of an AAV-HBV-infected mouse model

Background

Human hepatitis B virus (HBV) infection is an important public health issue in the Asia-Pacific region and is associated with chronic hepatitis, liver fibrosis, cirrhosis and even liver cancer. However, the underlying mechanisms of HBV-associated liver fibrosis remain incompletely understood.

Results

In the present study, proteomic and transcriptomic approaches as well as biological network analyses were performed to investigate the differentially expressed molecular signature and key regulatory networks that were associated with HBV-mediated liver fibrosis. RNA sequencing and 2DE-MALDI-TOF/TOF were performed on liver tissue samples obtained from HBV-infected C57BL/6 mouse generated via AAV8-HBV virus. The results showed that 322 genes and 173 proteins were differentially expressed, and 28 HBV-specific proteins were identified by comprehensive proteomic and transcriptomic analysis. GO analysis indicated that the differentially expressed proteins were predominantly involved in oxidative stress, which plays a key role in HBV-related liver fibrosis. Importantly, CAT, PRDX1, GSTP1, NXN and BLVRB were shown to be associated with oxidative stress among the differentially expressed proteins. The most striking results were validated by Western blot and RT-qPCR. The RIG-I like receptor signaling pathway was found to be the major signal pathway that changed during HBV-related fibrosis.

Conclusions

This study provides novel insights into HBV-associated liver fibrosis and reveals the significant role of oxidative stress in liver fibrosis. Furthermore, CAT, BLVRB, NXN, PRDX1, and IDH1 may be candidates for detection of liver fibrosis or therapeutic targets for the treatment of liver fibrosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3984-z) contains supplementary material, which is available to authorized users.

Annexin A2 promotes liver fibrosis by mediating von Willebrand factor secretion

BACKGROUND

Liver fibrosis can lead to cirrhosis and hepatocellular carcinoma if not treated in the early stages. The molecular mechanisms of the pathogenesis of hepatic fibrosis remain unclear.

AIM

To identify the molecules involved in the pathogenesis of liver fibrosis and to investigate the potential effect and mechanism of Annexin A2 up-regulation during liver fibrosis progression.

METHODS

Twenty Sprague-Dawley rats were divided into two groups: the carbon tetrachloride (CCl₄)-induced liver fibrosis group and the normal control group. Hematoxylin and eosin staining or Masson Trichrome staining and enzyme-linked immunosorbent assay were applied to assess the degree of liver damage and fibrosis in rats with CCl₄-induced liver fibrosis. Liver tissue protein profiles were analyzed using iTRAQ and mass spectrometry. RT-PCR and western blotting analyses were employed to validate differentially expressed proteins. Small interfering RNA-based silencing was performed to study the function of Annexin A2.

RESULTS

Twelve weeks after CCl₄ injection, significant body weight changes and liver injury and liver fibrosis were observed in rats. In addition, 130 proteins were differentially expressed in the liver fibrosis group. Overexpression of Annexin A2 was confirmed by RT-PCR and Western blotting analysis. Silencing of Annexin A2 expression in HepG2 and LX-2 cells significantly reduced the secretion of von Willebrand factor (vWF).

CONCLUSION

Annexin A2 promotes liver fibrosis by mediating vWF secretion, which can be used to mitigate the progression of liver fibrosis.

Specifically Formed Corona on Silica Nanoparticles Enhances Transforming Growth Factor β1 Activity in Triggering Lung Fibrosis

A corona is a layer of macromolecules formed on a nanoparticle surface in vivo. It can substantially change the biological identity of nanomaterials and possibly trigger adverse responses from the body tissues. Dissecting the role of the corona in the development of a particular disease may provide profound insights for understanding toxicity of nanomaterials in general. In our present study, we explored the capability of different silica nanoparticles (SiNPs) to induce silicosis in the mouse lung and analyzed the composition of coronas formed on these particles. We found that SiNPs of certain size and surface chemistry could specifically recruit transforming growth factor β1 (TGF-β1) into their corona, which subsequently induces the development of lung fibrosis. Once embedded into the corona on SiNPs, TGF-β1 was remarkably more stable than in its free form, and its fibrosis-triggering activity was significantly prolonged. Our study meaningfully demonstrates that a specific corona component on a certain nanoparticle could initiate a particular pathogenic process in a clinically relevant disease model. Our findings may shed light on the understanding of molecular mechanisms of human health risks correlated with exposure to small-scale substances.

Hepatitis B virus large surface protein: function and fame

Chronic infection with hepatitis B virus (HBV) is the leading cause of liver cirrhosis and hepatocellular carcinoma worldwide. HBV life cycle begins with viral attachment to hepatocytes, mediated by the large HBV surface protein (LHBs). Identification of the sodium-taurocholate cotransporting polypeptide (NTCP) as a HBV receptor has revealed a suitable target for viral entry inhibition. Analysis of serum hepatitis B surface antigen (HBsAg) level is a non-invasive diagnostic parameter that improves HBV treatment opportunities. Furthermore, HBsAg plays an important role in manipulation of host immune response by HBV. However, observations in patients with chronic hepatitis B under conditions of immune suppression and in transgenic mouse models of HBV infection suggest, that in absence of adaptive immune responses cellular mechanisms induced by HBV may also lead to the development of liver diseases. Thus, the multifaceted pathological aspects of HBsAg predetermine the design of new therapeutical options modulating associated biological implications.

Pathological impact of hepatitis B virus surface proteins on the liver is associated with the host genetic background

Background

While the immune pathogenesis caused by hepatitis B virus (HBV) infection has been studied extensively, little is known about direct pathogenic effects of HBV surface proteins. Here, we have investigated pathological cellular effects of HBV surface protein expression in the liver of transgenic mice with different genetic background.

Methods

The impact of HBV surface protein expression on the liver was studied in two mouse strains, BALB/c and C57BL/6. Histology and hydroxyproline assays were performed to investigate liver morphology and fibrosis. Gene expression and signaling were analyzed by microarray, qPCR and Western blotting.

Results

Expression of HBV surface proteins in the liver of transgenic mice induced activation of protein kinase-like endoplasmic reticulum kinase (PERK) and eukaryotic initiation factor 2α (eIF2α) phosphorylation. Phosphorylation of eIF2α resulted in activation of the ER stress markers glucose regulated protein (GRP) 78 and pro-apoptotic C/EBP homologous protein (CHOP) in transgenic mice on BALB/c genetic background leading to stronger liver injury and fibrosis in comparison with transgenic mice on C57BL/6 background. Hepatic stellate cells represented the main collagen-producing liver cells in HBV transgenic mice. The key regulators of hepatocyte proliferation, transcription factors c-Jun and STAT3 were activated in HBV transgenic mice. Tumour incidence in transgenic mice was strain- and sex-dependent.

Conclusions

Extent of liver injury, fibrosis, and tumour development induced by hepatic HBV surface protein expression considerably depends on host genetic background.

Proteome analysis of hepatic non-parenchymal cells of immune liver fibrosis rats

Elucidation of the mechanisms of liver fibrogenesis is important to treat liver fibrosis. In this study, we established rat models of liver fibrosis with stages from 0-1, 2, and 3-4 to 4 at 2, 4, 6, and 8 weeks, respectively, by injection of pig serum. Liver fibrogenesis was detected by Masson's trichrome staining. Rat non-parenchymal cells (NPCs) were enriched 4-fold by Percoll density gradient centrifugation. Protein extracts from NPCs were prepared at 4 and 8 weeks, separated by two-dimensional electrophoresis, and then stained with Coomassie Blue G-250. At 4 weeks, we identified 18 non-redundant differentially expressed proteins of which protein disulfide-isomerase associated protein 3 (PDIA3) and NDUV showed consistent expression at protein and mRNA levels from 4 to 8 weeks. PDIA3 was found to be down-regulated by Western blotting in the rat model and immunohistochemically in human liver. Our results revealed important aspects of the pathogenesis/progression of liver fibrosis and demonstrated important changes in protein expression levels of NPCs at various stages of liver fibrosis.

Dipyridamole prevents triple-negative breast-cancer progression

Dipyridamole is a widely prescribed drug in ischemic disorders, and it is here investigated for potential clinical use as a new treatment for breast cancer. Xenograft mice bearing triple-negative breast cancer 4T1-Luc or MDA-MB-231T cells were generated. In these in vivo models, dipyridamole effects were investigated for primary tumor growth, metastasis formation, cell cycle, apoptosis, signaling pathways, immune cell infiltration, and serum inflammatory cytokines levels. Dipyridamole significantly reduced primary tumor growth and metastasis formation by intraperitoneal administration. Treatment with 15 mg/kg/day dipyridamole reduced mean primary tumor size by 67.5 % (p = 0.0433), while treatment with 30 mg/kg/day dipyridamole resulted in an almost a total reduction in primary tumors (p = 0.0182). Experimental metastasis assays show dipyridamole reduces metastasis formation by 47.5 % in the MDA-MB-231T xenograft model (p = 0.0122), and by 50.26 % in the 4T1-Luc xenograft model (p = 0.0292). In vivo dipyridamole decreased activated β-catenin by 38.64 % (p < 0.0001), phospho-ERK1/2 by 25.05 % (p = 0.0129), phospho-p65 by 67.82 % (p < 0.0001) and doubled the expression of IkBα (p = 0.0019), thus revealing significant effects on Wnt, ERK1/2-MAPK and NF-kB pathways in both animal models. Moreover dipyridamole significantly decreased the infiltration of tumor-associated macrophages and myeloid-derived suppressor cells in primary tumors (p < 0.005), and the inflammatory cytokines levels in the sera of the treated mice. We suggest that when used at appropriate doses and with the correct mode of administration, dipyridamole is a promising agent for breast-cancer treatment, thus also implying its potential use in other cancers that show those highly activated pathways.

Plasma membrane proteome analysis of the early effect of alcohol on liver: implications for alcoholic liver disease

In humans, the over-consumption of alcohol can lead to serious liver disease. To examine the early effects of alcohol on liver disease, rats were given sufficient ethanol to develop liver cirrhosis. Rats before the onset of fibrosis were studied in this work. Plasma membranes (PM) of liver were extracted by twice sucrose density gradient centrifugation. The proteome profiles of PM from ethanol-treated rats and the controls were analyzed using two-dimensional gel electrophoresis (2-DE) and isobaric tag for relative and absolute quantitation (iTRAQ) technology. Ethanol treatment altered the amount of 15 different liver proteins: 10 of them were detected by 2-DE and 5 by iTRAQ. Keratin 8 was detected by both methods. Gene ontology analysis of these differentially detected proteins indicated that most of them were involved in important cell functions such as binding activity (including ion, DNA, ATP binding, etc.), cell structure, or enzyme activity. Among these, annexin A2, keratin 8, and keratin 18 were further verified using western blot analysis and annexin A2 was verified by immunohistochemistry. Our results suggested that alcohol has the potential to affect cell structure, adhesion and enzyme activity by altering expression levels of several relevant proteins in the PM. To the best of our knowledge, this is the first time to study the effect of alcohol on the liver PM proteome and it might be helpful for understanding the possible mechanisms of alcohol-induced liver disease.

Subcellular proteome analysis unraveled annexin A2 related to immune liver fibrosis

It is important to study the mechanism of liver fibrogenesis, and find new non-invasive biomarkers. In this study, we used subcellular proteomic technology to study the plasma membrane (PM) proteins related to immune liver fibrosis and search for new non-invasive biomarkers. A rat liver fibrosis model was induced by pig serum injection. The liver fibrogenesis from stage (S) S0-1, S2, S3-4, and S4 was detected by Masson staining and HE staining in this rat model after 2, 4, 6, and 8 weeks of treatment. The liver PM was enriched and analyzed using subcellular proteomic technology. The differentially expressed proteins were verified by Western blotting, immunohistochemistry, and ELISA. PM with 149-fold purification was obtained and 22 differentially expressed proteins were identified. Of which, annexin A2 (ANXA2) was detected to be increased obviously in S4 compared with S0-1, and verified by Western blotting of rat liver tissue and immunohistochemistry of rat and human liver tissue. The expression of ANXA2 in human plasma with S1-2 was also found to be up-regulated for 1.4-fold than that in S0. Furthermore, ANXA2 was detected to translocate from nuclear membrane and cytosol to PM as HBV stimulation through immunocytochemical analysis in vitro. This study identified 22 differentially expressed proteins related to liver fibrosis, and verified a potential biomarker (ANXA2) for non-invasive diagnosis of immune liver fibrosis. To our knowledge, it was the first time to dynamically study the proteins related to liver fibrosis and select biomarkers for liver fibrosis diagnosis through PM proteome research.

Integrated hepatic transcriptome and proteome analysis of mice with high-fat diet-induced nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver disease in the US and refers to a wide spectrum of liver damage, including simple steatosis, steatohepatitis, fibrosis and cirrhosis. The goal of the present study was to achieve a more detailed understanding of the molecular changes in response to high fat-induced liver steatosis through the identification of a differentially expressed liver transcriptome and proteome. Male C57/BL6 mice fed a high-fat lard diet for 8 weeks developed visceral obesity and hepatic steatosis characterized by significantly increased liver and plasma free fatty acid and triglyceride levels and plasma alanine aminotransferase activities. Transcriptome analysis demonstrated that, compared to the control diet (CD), high-fat diet changed the expression of 309 genes (132 up- and 177 down-regulated; by a twofold change and more, P<.05). Multiple genes encoding proteins involved in lipogenesis were down-regulated, whereas genes involved in fatty acid oxidation were up-regulated. Proteomic analysis revealed 12 proteins which were differentially expressed. Of these, glutathione S-transferases mu1 and pi1 and selenium-binding protein 2 were decreased at both the gene and protein levels. This is the first study to perform a parallel transcriptomic and proteomic analysis of diet-induced hepatic steatosis. Several key pathways involving xenobiotic and lipid metabolism, the inflammatory response and cell-cycle control were identified. These pathways provide targets for future mechanistic and therapeutic studies as related to the development and prevention of NAFLD.