Mechanisms of action of acetaldehyde in the up-regulation of the human α2(I) collagen gene in hepatic stellate cells: key roles of Ski, SMAD3, SMAD4, and SMAD7

Unaltered hepatic wound healing response in male rats with ancestral liver injury

The possibility that ancestral environmental exposure could result in adaptive inherited effects in mammals has been long debated. Numerous rodent models of transgenerational responses to various environmental factors have been published but due to technical, operational and resource burden, most still await independent confirmation. A previous study reported multigenerational epigenetic adaptation of the hepatic wound healing response upon exposure to the hepatotoxicant carbon tetrachloride (CCl4) in male rats. Here, we comprehensively investigate the transgenerational effects by repeating the original CCl4 multigenerational study with increased power, pedigree tracing, F2 dose-response and suitable randomization schemes. Detailed pathology evaluations do not support adaptive phenotypic suppression of the hepatic wound healing response or a greater fitness of F2 animals with ancestral liver injury exposure. However, transcriptomic analyses identified genes whose expression correlates with ancestral liver injury, although the biological relevance of this apparent transgenerational transmission at the molecular level remains to be determined. This work overall highlights the need for independent evaluation of transgenerational epigenetic inheritance paradigms in mammals.

Insights of mitochondrial involvement in alcoholic fatty liver disease

Alcoholic liver disease (ALD) is a global concern affecting most of the population and leading to the development of end-stage liver disease. Metabolic alterations due to increased alcohol consumption surge the hepatic accumulation of lipids and develop into a severe form of alcoholic steatohepatitis (ASH), depending on age and the consumption rate. The mitochondria in the hepatocyte actively regulate metabolic homeostasis and are disrupted in ALD pathogenesis. The increased NADH upon ethanol metabolism inhibits the mitochondrial oxidation of fatty acids, alters oxidative phosphorylation, and favors de novo lipogenesis. The higher mitochondrial respiration in early ALD increases free radical generation, whereas mitochondrial respiration is uncoupled in chronic ALD, affecting the cellular energy status. The defective glutathione importer due to excessive cholesterol loading and low adenosine triphosphate accounts for additional oxidative stress leading to hepatocyte apoptosis. The defective mitochondrial transcription machinery and sirtuins function in ALD affect mitochondrial function and biogenesis. The metabolites of ethanol metabolism epigenetically alter the gene expression profile of hepatic cell populations by modulating the promoters and sirtuins, aiding hepatic fibrosis and inflammation. The defect in mitophagy increases the accumulation of megamitochondria in hepatocytes and attracts immune cells by releasing mitochondrial damage-associated molecular patterns to initiate hepatic inflammation and ASH progression. Thus, maintaining mitochondrial lipid homeostasis and antioxidant capacity pharmacologically could provide a better outcome for ALD management.

A Meta-Analysis of Preclinical Studies to Investigate the Effect of Panax ginseng on Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) has become a major global concern, but the development of effective drugs remains a challenge despite numerous preclinical and clinical pieces of research on the effects of natural compounds. To address this, a meta-analysis was conducted on the efficacy of Panax ginseng for ALD based on preclinical studies. We identified 18 relevant studies from PubMed, Web of Science, and Cochrane Library database and evaluated their methodological quality using the Systematic Review Centre for Laboratory animal Experimentation tool. We analyzed the data using I2, p-values, and fixed effects models to assess overall efficacy and heterogeneity. The results of the meta-analysis suggested that Panax ginseng treatment is effective in reducing the levels of inflammatory markers associated with hepatic injury caused by ALD in animal experiments. Additionally, the administration of Panax ginseng was found to down-regulate inflammatory cytokines and attenuate lipid metabolism in ALD. Moreover, Panax ginseng markedly improved the antioxidant systems in ALD. Therefore, we concluded that Panax ginseng has the potential to be a promising therapeutic agent for ALD. Further research is needed to confirm these findings and to determine the optimal dosage and duration of treatment for patients with ALD.

Mycoviruses in Fungi: Carcinogenesis of Fungal Agents May Not Always Be Mycotoxin Related

Certain viruses have been found to induce diverse biological pathways to carcinogenesis, evidenced by the presence of viral gene products in some tumors. Despite the fact that many fungal agents contain mycoviruses, until recently, their possible direct effects on human health, including carcinogenesis and leukemogenesis, had not been explored. In this regard, most studies of fungal agents have rightly concentrated on their mycotoxin formation and effects. Recently, the direct role of yeasts and fungi in the etiology of cancers, including leukemia, have been investigated. While greater attention has been placed on the carcinogenic effects of Candida, the role of filamentous fungi in carcinogenesis has also been explored. Recent findings from studies using the enzyme-linked immunosorbent assay (ELISA) technique indicate that the plasma of patients with acute lymphoblastic leukemia (ALL) uniformly contains antibodies for a certain mycovirus-containing Aspergillus flavus, while controls are negative. The exposure of mononuclear leukocytes from patients with ALL in full remission, and long-term survivors, to the product of this organism was reported to result in the re-development of typical genetics and cell surface phenotypes characteristic of active ALL. Mycoviruses are known to be able to significantly alter the biological characteristics and functions of their host. The possible carcinogenic and leukemogenic role of mycoviruses, with and without their host, needs to be further investigated.

Overexpressed ski efficiently promotes neurorestoration, increases neuronal regeneration, and reduces astrogliosis after traumatic brain injury

Traumatic brain injury (TBI) survivors suffer from long-term disability and neuropsychiatric sequelae due to irreparable brain tissue destruction. However, there are still few efficient therapies to promote neurorestoration in damaged brain tissue. This study aimed to investigate whether the pro-oncogenic gene ski can promote neurorestoration after TBI. We established a ski-overexpressing experimental TBI mouse model using adenovirus-mediated overexpression through immediate injection after injury. Hematoxylin-eosin staining, MRI-based 3D lesion volume reconstruction, neurobehavioral tests, and analyses of neuronal regeneration and astrogliosis were used to assess neurorestorative efficiency. The effects of ski overexpression on the proliferation of cultured immature neurons and astrocytes were evaluated using imaging flow cytometry. The Ski protein level increased in the perilesional region at 3 days post injury. ski overexpression further elevated Ski protein levels up to 14 days post injury. Lesion volume was attenuated by approximately 36-55% after ski overexpression, with better neurobehavioral recovery, more newborn immature and mature neurons, and less astrogliosis in the perilesional region. Imaging flow cytometry results showed that ski overexpression elevated the proliferation rate of immature neurons and reduced the proliferation rate of astrocytes. These results show that ski can be considered a novel neurorestoration-related gene that effectively promotes neurorestoration, facilitates neuronal regeneration, and reduces astrogliosis after TBI.

Effect and mechanism of pirfenidone combined with 2-methoxy-estradiol perfusion through portal vein on hepatic artery hypoxia-induced hepatic fibrosis

PURPOSE

The aim of this study was to explore the effect and mechanism of pirfenidone (PFD) combined with 2-methoxyestradiol (2-ME2) perfusion through portal vein on hepatic artery hypoxia-induced hepatic fibrosis.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into 5 groups (n ​= ​3/group): control group, hepatic artery ligation (HAL) group, HAL ​+ ​PFD (portal vein perfusion of PFD) group, HAL+2-ME2 (portal vein perfusion of 2-ME2) group and HAL ​+ ​PFD+2-ME2 group depending on whether they received HAL and/or portal vein perfusion (PFD and/or 2-ME2). Livers were harvested for pathology, western blotting (WB), and quantitative real-time PCR (qRT-PCR).

RESULTS

Sirius red staining showed that portal vein perfusion of drugs resulted in degradation of liver fibrosis. Immunohistochemistry showed decreased hypoxia-inducible factor-1 α (HIF-1α) and α-smooth muscle actin (α-SMA) after portal intravenous drugs infusion compared with HAL group (P ​< ​0.05). WB analysis showed increased Smad7 in HAL ​+ ​PFD group compared with HAL group (P ​< ​0.05). qRT-PCR analysis showed decreased matrix metallo-proteinase 2 (MMP2), transforming growth factor β1 (TGF-β1), monocyte chemoattractant protein-1 (MCP-1), and Collagen I mRNA in HAL ​+ ​PFD group except for tissue inhibitor of metalloproteinase-1 (TIMP-1) compared with HAL group (P ​< ​0.05). Compared with HAL ​+ ​PFD group, the addition of 2-ME2 did not lead to better results in qRT-PCR analysis.

CONCLUSIONS

The portal vein perfusion of PFD significantly reduced the hepatic artery hypoxia-induced fibrosis degree in treated rats by down-regulating the expression of HIF-1α, α-SMA, MMP2, TGF-β1, MCP-1, and Collagen I, as well as up-regulating the TIMP-1 expression and Smad7 protein level. Combined 2-ME2 infusion was not better than PFD alone.

Analysis of the interaction between A1 R and A2A R proteins in living cells based on FRET imaging and batch processing method

The quantitative FRET analysis of living cells is a tedious and time-consuming task for freshman lacks technical training. In this study, FRET imaging and batch processing method were combined to analyze reagents-induced interactions of A₁ R and A_2A R on cell membranes. Results showed that the method had taken less time than if cell-by-cell was analyzed. The accuracy and repeatability of FRET efficiency values were likewise improved by removing the interference from anthropogenic factors. Then this method was applied to rapidly analyze acetaldehyde-induced interactions, which analyzed hundreds of single-cell trends by one operation, and the results revealed that interactions were consistently attenuated in LX-2 cells, and statistical differences appeared after 30 min. Combined with batch processing method, procedures of cells FRET analysis have been greatly simplified without additional technical work, which has broad prospects in large-scale analysis of cellar protein interaction.

A review on association of fungi with the development and progression of carcinogenesis in the human body

The role and impact of commensal and pathogenic fungi in different parts of the human body are being increasingly appreciated, unveiling the importance of such microorganisms in human health. A key function is the involvement of the mycobiota in cross-kingdom interactions within the microbiome. Any disturbance in the functionality of the microbiota could alter metabolic reactions, have a negative impact on homeostasis or induce diseases. The association of fungi with cancer development is the focus of this review. Several studies have reported direct or indirect involvement of fungal pathogens and mycobiome dysbiosis in induction of carcinogenesis. Most studies focused on cancers of the gastrointestinal tract. However, researchers are now investigating other organs, such as the skin, where the significant results obtained confirm the involvement of fungal pathogens and administration of antifungal drugs in development of cancer. This review gives an overview of the different organs affected and describes the mechanisms used by these eukaryotes or antifungals to induce oncogenesis.

cAMP Signaling in Pathobiology of Alcohol Associated Liver Disease

The importance of cyclic adenosine monophosphate (cAMP) in cellular responses to extracellular signals is well established. Many years after discovery, our understanding of the intricacy of cAMP signaling has improved dramatically. Multiple layers of regulation exist to ensure the specificity of cellular cAMP signaling. Hence, disturbances in cAMP homeostasis could arise at multiple levels, from changes in G protein coupled receptors and production of cAMP to the rate of degradation by phosphodiesterases. cAMP signaling plays critical roles in metabolism, inflammation and development of fibrosis in several tissues. Alcohol-associated liver disease (ALD) is a multifactorial condition ranging from a simple steatosis to steatohepatitis and fibrosis and ultimately cirrhosis, which might lead to hepatocellular cancer. To date, there is no FDA-approved therapy for ALD. Hence, identifying the targets for the treatment of ALD is an important undertaking. Several human studies have reported the changes in cAMP homeostasis in relation to alcohol use disorders. cAMP signaling has also been extensively studied in in vitro and in vivo models of ALD. This review focuses on the role of cAMP in the pathobiology of ALD with emphasis on the therapeutic potential of targeting cAMP signaling for the treatment of various stages of ALD.

Aldehyde Dehydrogenase, Liver Disease and Cancer

Acetaldehyde dehydrogenase 2 (ALDH2) is the key enzyme responsible for metabolism of the alcohol metabolite acetaldehyde in the liver. In addition to conversion of the acetaldehyde molecule, ALDH is also involved in other cellular functions. Recently, many studies have investigated the involvement of ALDH expression in viral hepatitis, alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), liver fibrosis, and liver cancer. Notably, ALDH2 expression has been linked with liver cancer risk, as well as pathogenesis and prognosis, and has emerged as a promising therapeutic target. Of note, approximately 8% of the world's population, and approximately 30-40% of the population in East Asia carry an inactive ALDH2 gene. This review summarizes new progress in understanding tissue-specific acetaldehyde metabolism by ALDH2 as well as the association of ALDH2 gene polymorphisms with liver disease and cancer. New research directions emerging in the field are also briefly discussed.

Alpha Mangostin Inhibits the Proliferation and Activation of Acetaldehyde Induced Hepatic Stellate Cells through TGF-β and ERK 1/2 Pathways

Liver fibrosis is characterized by excessive accumulation of extracellular matrix in chronic liver injury. Alcohol-induced fibrosis may develop into cirrhosis, one of the major causes of liver disease mortality. Previous studies have shown that alpha mangostin can decrease ratio of pSmad/Smad and pAkt/Akt in TGF-β-induced liver fibrosis model in vitro. Further investigation of the mechanism of action of alpha mangostin in liver fibrosis model still needs to be done. The present study aimed to analyze the mechanism of action of alpha mangostin on acetaldehyde induced liver fibrosis model on TGF-β and ERK 1/2 pathways. Immortalized HSCs, LX-2 cells, were incubated with acetaldehyde, acetaldehyde with alpha mangostin (10 and 20 μM), or alpha mangostin only (10 μM). Sorafenib 10 μM was used as positive control. LX-2 viability was counted using trypan blue exclusion method. The effect of alpha mangostin on hepatic stellate cells proliferation and activation markers and its possible mechanism of action via TGF-β and ERK1/2 were studied. Acetaldehyde was shown to increase proliferation and expression of profibrogenic and migration markers on HSC, while alpha mangostin treatment resulted in a reduced proliferation and migration of HSC and decreased Ki-67 and pERK 1/2 expressions. These findings were followed with decreased expressions and concentrations of TGF-β; decreased expression of Col1A1, TIMP1, and TIMP3; increased expression of MnSOD and GPx; and reduction in intracellular reactive oxygen species. These effects were shown to be dose dependent. Therefore, we conclude that alpha mangostin inhibits hepatic stellate cells proliferation and activation through TGF-β and ERK 1/2 pathways.

Smad4-dependent regulation of type I collagen expression in the muscle of grass carp fed with faba bean

Smad4 is the key regulator in the transforming growth factor β1 (TGF-β1)/Smads signal pathway, and is also the crux of the regulation of type I collagen expression in mammals. In fish, however, the relationship between Smad4 and type I collagen is still unknown. Given the widely accepted importance of type I collagen in fish muscle hardness, we seek to explore this issue by analyzing the expressions of the TGF-β1/Smads pathway molecules and type I collagen in the muscle of crisp grass carp fed with faba bean, which shows increased muscle hardness. The study found that (1) in the process of feeding the grass carp with faba bean, the mRNA and protein expressions of TGF-β1, Smad2 and Smad4 all increased along with the increase of type I collagen expression (Col1α1 and Col1α2); (2) one day after the injection of Smad4 over-expression vector, both mRNA and protein expressions of Col1α1 and Col1α2 significantly increased, reaching the maximum on the 2nd and 5th day, respectively; (3) one day after the injection of Smad4 RNAi interference vector, the mRNA and protein expressions of Col1α1 and Col1α2 decreased, reaching the minimum on the 5th day. These results revealed that Smad4 is the major regulator of type I collagen in the muscle of grass carp fed with faba bean. This study would provide an important mechanistic basis for nutritional regulation of type I collagen in the muscle of fish.

Organ and tissue fibrosis: Molecular signals, cellular mechanisms and translational implications

Fibrosis denotes excessive scarring, which exceeds the normal wound healing response to injury in many tissues. Although the extracellular matrix deposition appears unstructured disrupting the normal tissue architecture and subsequently impairing proper organ function, fibrogenesis is a highly orchestrated process determined by defined sequences of molecular signals and cellular response mechanisms. Persistent injury and parenchymal cell death provokes tissue inflammation, macrophage activation and immune cell infiltration. The release of biologically highly active soluble mediators (alarmins, cytokines, chemokines) lead to the local activation of collagen producing mesenchymal cells such as pericytes, myofibroblasts or Gli1 positive mesenchymal stem cell-like cells, to a transition of various cell types into myofibroblasts as well as to the recruitment of fibroblast precursors. Clinical observations and experimental models highlighted that fibrosis is not a one-way road. Specific mechanistic principles of fibrosis regression involve the resolution of chronic tissue injury, the shift of inflammatory processes towards recovery, deactivation of myofibroblasts and finally fibrolysis of excess matrix scaffold. The thorough understanding of common principles of fibrogenic molecular signals and cellular mechanisms in various organs - such as liver, kidney, lung, heart or skin - is the basis for developing improved diagnostics including biomarkers or imaging techniques and novel antifibrotic therapeutics.

Transcriptional cofactors Ski and SnoN are major regulators of the TGF-β/Smad signaling pathway in health and disease

The transforming growth factor-β (TGF-β) family plays major pleiotropic roles by regulating many physiological processes in development and tissue homeostasis. The TGF-β signaling pathway outcome relies on the control of the spatial and temporal expression of >500 genes, which depend on the functions of the Smad protein along with those of diverse modulators of this signaling pathway, such as transcriptional factors and cofactors. Ski (Sloan-Kettering Institute) and SnoN (Ski novel) are Smad-interacting proteins that negatively regulate the TGF-β signaling pathway by disrupting the formation of R-Smad/Smad4 complexes, as well as by inhibiting Smad association with the p300/CBP coactivators. The Ski and SnoN transcriptional cofactors recruit diverse corepressors and histone deacetylases to repress gene transcription. The TGF-β/Smad pathway and coregulators Ski and SnoN clearly regulate each other through several positive and negative feedback mechanisms. Thus, these cross-regulatory processes finely modify the TGF-β signaling outcome as they control the magnitude and duration of the TGF-β signals. As a result, any alteration in these regulatory mechanisms may lead to disease development. Therefore, the design of targeted therapies to exert tight control of the levels of negative modulators of the TGF-β pathway, such as Ski and SnoN, is critical to restore cell homeostasis under the specific pathological conditions in which these cofactors are deregulated, such as fibrosis and cancer.

Proteins that repress molecular signaling through the transforming growth factor-beta (TGF-β) pathway offer promising targets for treating cancer and fibrosis. Marina Macías-Silva and colleagues from the National Autonomous University of Mexico in Mexico City review the ways in which a pair of proteins, called Ski and SnoN, interact with downstream mediators of TGF-β to inhibit the effects of this master growth factor. Aberrant levels of Ski and SnoN have been linked to diverse range of diseases involving cell proliferation run amok, and therapies that regulate the expression of these proteins could help normalize TGF-β signaling to healthier physiological levels. For decades, drug companies have tried to target the TGF-β pathway, with limited success. Altering the activity of these repressors instead could provide a roundabout way of remedying pathogenic TGF-β activity in fibrosis and oncology.

Transcriptomic Profiling of Obesity-Related Nonalcoholic Steatohepatitis Reveals a Core Set of Fibrosis-Specific Genes

Nonalcoholic steatohepatitis (NASH) is strongly associated with obesity and type 2 diabetes. The molecular factors underlying the development of inflammation and severe fibrosis in NASH remain largely unknown. The purpose of this study was to identify gene expression patterns related to obesity-related NASH inflammation and fibrosis. We performed sequencing-based mRNA profiling analysis of liver samples from individuals with normal histology (n = 24), lobular inflammation (n = 53), or bridging fibrosis, incomplete cirrhosis, or cirrhosis (n = 65). Hepatic expression of a subset of mRNAs was validated using an orthogonal method, analyzed in a hepatic stellate cell line, and used to identify transcriptional patterns shared by other forms of cirrhosis. We observed evidence for differential levels of 3820 and 2980 transcripts in lobular inflammation and advanced fibrosis, respectively, compared with normal histology (false discovery rate ≤0.05), including 176 genes specific to fibrosis. Functional enrichment analysis of these genes revealed participation in pathways involving cytokine-cytokine receptor interaction, PI3K-Akt signaling pathway, focal adhesion, and extracellular matrix-receptor interaction. We identified 34 differentially expressed transcripts in comparisons of lobular inflammation and fibrosis, a proportion of which were also upregulated during activation of hepatic stellate cells. A set of 16 genes from a previous independent study of NASH bridging fibrosis/cirrhosis were replicated, several of which have also been associated with advanced fibrosis/cirrhosis due to hepatitis viruses or alcohol in human patients. Dysregulated mRNA expression is associated with inflammation and fibrosis in NASH. Advanced NASH fibrosis is characterized by distinct set of molecular changes that are shared with other causes of cirrhosis.

SREBP1c mediates the effect of acetaldehyde on Cidea expression in Alcoholic fatty liver Mice

Cell death inducing DNA fragmentation factor-alpha-like A (Cidea) is a member of cell death-inducing DFF45-like effector (CIDE) protein. The initial function of CIDE is the promotion of cell death and DNA fragmentation in mammalian cells. Cidea was recently reported to play critical roles in the development of hepatic steatosis. The purpose of present study is to determine the effect of chronic alcohol intake on Cidea expression in the livers of mice with alcoholic fatty liver disease. Cidea expression was significantly increased in the liver of alcohol-induced fatty liver mice. While, knockdown of Cidea caused lipid droplets numbers reduction. Next, we detected the activity of ALDH2 reduction and the concentration of serum acetaldehyde accumulation in our alcohol-induced fatty liver mice. Cidea expression was elevated in AML12 cells exposed to 100uM acetaldehyde. Interestingly, Dual-luciferase reporter gene assay showed that 100 uM acetaldehyde led to the activation of Cidea reporter gene plasmid which containing SRE element. What’s more, the knockdown of SREBP1c suppressed acetaldehyde-induced Cidea expression. Overall, our findings suggest that Cidea is highly associated with alcoholic fatty liver disease and Cidea expression is specifically induced by acetaldehyde, and this up-regulation is most likely mediated by SREBP1c.

Aldehyde dehydrogenase 2 gene polymorphisms and liver diseases

Liver diseases are one of major causes of disease burden in China. The composition of chronic liver diseases has changed significantly in China over the past years. The incidence of alcoholic liver disease has increased gradually. Acetaldehyde dehydrogenase 2 (ALDH2) is the principle enzyme responsible for hepatic metabolism of ethanol. Approximately 8% of individuals have the inactive ALDH2 genotype around the world, especially in the East Asian population. Presence of the mutant or inactive ALDH2*2 gene may lead to accumulation of acetaldehyde as the ethanol metabolite. Acetaldehyde is a toxic material which can cause multiple organs to be injured in the individuals with acetaldehyde accumulation. The relationship between the mutant ALDH2*2 gene and a variety of liver disorders including alcoholic liver disease needs to be explored. In the present article, we review the recent advances in understanding the relationship between ALDH2 gene polymorphisms and liver diseases, in order to provide a better understanding of the difference in the characteristics of liver disease between the Eastern and Western populations, which can help develop new strategies to prevent and treat liver diseases.

Intestinal flora imbalance promotes alcohol-induced liver fibrosis by the TGFβ/smad signaling pathway in mice

Intestinal flora performs a crucial role in human health and its imbalance may cause numerous pathological changes. The liver can also affect the intestinal function through bile secretion via the enterohepatic cycle. The pathophysiological association between the gut and the liver is described as the gut-liver axis. The present study investigated the role of intestinal flora in alcohol-induced liver fibrosis. A total of 36 C57 mice were randomly and equally divided into 3 different dietary regimes: Group I (alcohol injury; received alcohol); group II (alcohol injury with flora imbalance; received alcohol plus lincomycin hydrochloride) and group III (alcohol injury with corrected flora imbalance; received alcohol, lincomycin hydrochloride and extra probiotics). The present study then investigated several indicators of liver damage. Alkaline phosphatase (ALP) levels, aspartate aminotransferase (AST) levels and alanine aminotransferase (ALT) levels in mice serum were studied. Masson staining and Annexin V-fluorescein isothiocyanate/propidium iodide double staining was also performed, and the expression of mothers against decapentaplegic homolog (smad) 3 and smad4 proteins in hepatic stellate cells (HSCs) of the mice was examined using western blot analysis. The levels of serum ALP, AST and ALT were the highest in group II mice, and all 3 levels decreased in group III mice compared with those from group II. The degree of liver fibrosis was aggravated in group II mice compared with group I mice. The apoptosis of HSCs was significantly inhibited in group II mice, but was increased in group III mice. The HSCs in group II mice exhibited higher expression of smad3 and smad4, whilst group III mice (with corrected intestinal flora imbalance) exhibited downregulated expression of smad3 and smad4. The present data indicates that the intestinal flora perform a significant role in maintaining liver homeostasis. Furthermore, an imbalance of intestinal flora can exacerbate alcohol-induced liver fibrosis in mice through the transforming growth factor β/SMA/MAD homology signaling pathway, which subsequently leads to more serious liver damage.

miR‑21 promotes α‑SMA and collagen I expression in hepatic stellate cells via the Smad7 signaling pathway

The aim of the present study was to investigate the role of microRNA (miR)‑21 in regulating collagen I and Smad7 expression in activated rat hepatic stellate cells (HSCs). Rat HSCs were isolated by single‑step density gradient centrifugation with Nycodenz. Cellular content of miR‑21, SMAD7, α‑smooth muscle actin (α‑SMA), collagen type I alpha 1 (COLLA1) and COLL alpha 2 (A2) mRNA was examined by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR), and cellular content of Smad7 and α‑SMA protein was detected by western blotting. Binding of miR‑21 to the 3'‑untranslated region (UTR) of Smad7 was verified by dual‑luciferase assay. The authors observed that, in activated HSCs, expression of miR‑21 was significantly increased in a time‑dependent manner, while expression of Smad7 mRNA and protein was significantly reduced. In addition, miR‑21 mimics significantly enhanced cellular α‑SMA mRNA and protein content, while miR‑21 inhibitor significantly reduced α‑SMA mRNA and protein levels. Similarly, cellular content of COLLA1 and COLLA2 mRNA was significantly elevated by miR‑21 mimics, but reduced by miR‑21 inhibitor, in activated HSCs. Moreover, cellular content of Smad7 mRNA and protein was significantly reduced by miR‑21 mimics, but significantly increased by miR‑21 inhibitor. Furthermore, miR‑21 mimics activated firefly luciferase in HEK293 cells transfected with the wild type 3'‑UTR of Smad7. miR‑21 regulates expression of α‑SMA and collagen I in activated rat HSCs by directly targeting Smad7.

Purinergic P2X7 receptor mediates acetaldehyde-induced hepatic stellate cells activation via PKC-dependent GSK3β pathway

The activation of hepatic stellate cells (HSCs) is an essential part in the development of alcoholic liver fibrosis (ALF). In this study, stimulated HSCs with 200μM acetaldehyde for 48h was used to imitate alcoholic liver fibrosis in vitro. The western blot and qRT-PCR results showed that P2X7R expression was significantly increased in the activation of HSCs after acetaldehyde treatment. Interestingly, activation of P2X7R by stimulating with P2X7R agonist BzATP significantly promoted acetaldehyde-induced CyclinD1 expression, cell proportion in S phase, inflammatory response, and the protein and mRNA levels of α-SMA, collagen I. In contrast, blockage of P2X7R by stimulating with the inhibitor A438079 or transfecting with specific siRNA dramatically suppressed acetaldehyde-induced HSCs activation. Furthermore, PKC activation treated with PMA could obviously up-regulate the expression of α-SMA and collagen I and the phosphorylation of GSK3β, while inhibition of PKC significantly reduced GSK3β activation. Moreover, GSK3β inhibition harvested a dramatic decrease of the mRNA and protein levels of α-SMA and collagen I by suppressing GSK3β phosphorylation. Taken together, these results suggested that purinergic P2X7R mediated acetaldehyde-induced activation of HSCs via PKC-dependent GSK3β pathway, which maybe a novel target for limiting HSCs activation.

Ethanol and High Cholesterol Diet Causes Severe Steatohepatitis and Early Liver Fibrosis in Mice

Background and Aim

Because ethanol consumption is commonly associated with a high cholesterol diet, we examined whether combined consumption of ethanol and high cholesterol increases liver injury and fibrosis.

Methods

Male C57BL/6J mice were fed diets containing: 1) 35% of calories from corn oil (CTR), 2) CTR plus 0.5% (w/v) cholesterol (Chol), 3) CTR plus ethanol (27% of calories) (EtOH), or 4) EtOH+Chol for 3 months.

Results

In mice fed Chol or EtOH alone, ALT increased to ~160 U/L, moderate hepatic steatosis occurred, and leukocyte infiltration, necrosis, and apoptosis increased modestly, but no observable fibrosis developed. By contrast in mice fed EtOH+Chol, ALT increased to ~270 U/L, steatosis was more extensive and mostly macrovesicular, and expression of proinflammatory molecules (HMGB-1, TLR4, TNFα, ICAM-1) and leukocyte infiltration increased substantially. Necrosis and apoptosis also increased. Trichrome staining and second harmonic generation microscopy revealed hepatic fibrosis. Fibrosis was mostly sinusoidal and/or perivenular, but in some mice bridging fibrosis occurred. Expression of smooth muscle α-actin and TGF-β1 increased slightly by Chol, moderately by EtOH, and markedly by EtOH+Chol. TGF-β pseudoreceptor BAMBI increased slightly by Chol, remained unchanged by EtOH and decreased by EtOH+Chol. MicroRNA-33a, which enhances TGF-β fibrotic effects, and phospho-Smad2/3, the down-stream signal of TGF-β, also increased more greatly by EtOH+Chol than Chol or EtOH. Metalloproteinase-2 and -9 were decreased only by EtOH+Chol.

Conclusion

High dietary cholesterol and chronic ethanol consumption synergistically increase liver injury, inflammation, and profibrotic responses and suppress antifibrotic responses, leading to severe steatohepatitis and early fibrosis in mice.

Evaluation of urinary bladder fibrogenesis in a mouse model of long-term ketamine injection

Long-term ketamine abuse has been shown to affect the lower urinary tract and result in interstitial cystitis-like syndrome. However, the causative mechanism of ketamine-induced dysfunction remains unclear. The present study aimed to investigate the physiological, histological and molecular changes on ketamine-associated cystitis (KC) in a mouse model. Both male and female Balb/c mice were separately distributed into the control group (normal saline) and ketamine group, which received ketamine hydrochloride (100 mg/kg/day) daily by intraperitoneal injection for a total period of 20 weeks. In each group, the urine was analyzed by gas chromatography-mass spectrometry to measure the concentration of ketamine and its metabolites. Urinary frequency and urine volume were examined to investigate the urinary voiding functions. Mice bladders were excised for cDNA microarray and hematoxylin and eosin (HE) staining. The ketamine and metabolites were detected only in ketamine-treated mice urine. The voiding interval was reduced in the male mice group after 20 week ketamine administration. Additionally, the result of cDNA array analysis revealed a number of gene expression levels involved in chronic wound healing response and collagen accumulation, which were closely associated with fibrosis progression in the connective tissue. In HE staining of the bladder tissue, the ketamine-injected mice exhibited prominently denser blood vessel distribution in the submucosal layer. Based on the evidence in the present study, a mechanism that delineates fibrosis formation of urinary bladder induced by the pathogenesis of ketamine abuse can be constructed.

Microarray Study of Pathway Analysis Expression Profile Associated with MicroRNA-29a with Regard to Murine Cholestatic Liver Injuries

Accumulating evidence demonstrates that microRNA-29 (miR-29) expression is prominently decreased in patients with hepatic fibrosis, which consequently stimulates hepatic stellate cells' (HSCs) activation. We used a cDNA microarray study to gain a more comprehensive understanding of genome-wide gene expressions by adjusting miR-29a expression in a bile duct-ligation (BDL) animal model.

METHODS

Using miR-29a transgenic mice and wild-type littermates and applying the BDL mouse model, we characterized the function of miR-29a with regard to cholestatic liver fibrosis. Pathway enrichment analysis and/or specific validation were performed for differentially expressed genes found within the comparisons.

RESULTS

Analysis of the microarray data identified a number of differentially expressed genes due to the miR-29a transgene, BDL, or both. Additional pathway enrichment analysis revealed that TGF-β signaling had a significantly differential activated pathway depending on the occurrence of miR-29a overexpression or the lack thereof. Furthermore, overexpression was found to elicit changes in Wnt/β-catenin after BDL.

CONCLUSION

This study verified that an elevated miR-29a level could alleviate liver fibrosis caused by cholestasis. Furthermore, the protective effects of miR-29a correlate with the downregulation of TGF-β and associated with Wnt/β-catenin signal pathway following BDL.

Adipose tissue-liver axis in alcoholic liver disease

Alcoholic liver disease (ALD) remains an important health problem worldwide. The disease spectrum is featured by early steatosis, steatohepatitis (steatosis with inflammatory cells infiltration and necrosis), with some individuals ultimately progressing to fibrosis/cirrhosis. Although the disease progression is well characterized, no effective therapies are currently available for the treatment in humans. The mechanisms underlying the initiation and progression of ALD are multifactorial and complex. Emerging evidence supports that adipose tissue dysfunction contributes to the pathogenesis of ALD. In the first part of this review, we discuss the mechanisms whereby chronic alcohol exposure contributed to adipose tissue dysfunction, including cell death, inflammation and insulin resistance. It has been long known that aberrant hepatic methionine metabolism is a major metabolic abnormality induced by chronic alcohol exposure and plays an etiological role in the pathogenesis of ALD. The recent studies in our group documented the similar metabolic effect of chronic alcohol drinking on methionine in adipose tissue. In the second part of this review, we also briefly discuss the recent research progress in the field with a focus on how abnormal methionine metabolism in adipose tissue contributes to adipose tissue dysfunction and liver damage.

Metabolic derivatives of alcohol and the molecular culprits of fibro-hepatocarcinogenesis: Allies or enemies?

Chronic intake of alcohol undoubtedly overwhelms the structural and functional capacity of the liver by initiating complex pathological events characterized by steatosis, steatohepatitis, hepatic fibrosis and cirrhosis. Subsequently, these initial pathological events are sustained and ushered into a more complex and progressive liver disease, increasing the risk of fibro-hepatocarcinogenesis. These coordinated pathological events mainly result from buildup of toxic metabolic derivatives of alcohol including but not limited to acetaldehyde (AA), malondialdehyde (MDA), CYP2E1-generated reactive oxygen species, alcohol-induced gut-derived lipopolysaccharide, AA/MDA protein and DNA adducts. The metabolic derivatives of alcohol together with other comorbidity factors, including hepatitis B and C viral infections, dysregulated iron metabolism, abuse of antibiotics, schistosomiasis, toxic drug metabolites, autoimmune disease and other non-specific factors, have been shown to underlie liver diseases. In view of the multiple etiology of liver diseases, attempts to delineate the mechanism by which each etiological factor causes liver disease has always proved cumbersome if not impossible. In the case of alcoholic liver disease (ALD), it is even more cumbersome and complicated as a result of the many toxic metabolic derivatives of alcohol with their varying liver-specific toxicities. In spite of all these hurdles, researchers and experts in hepatology have strived to expand knowledge and scientific discourse, particularly on ALD and its associated complications through the medium of scientific research, reviews and commentaries. Nonetheless, the molecular mechanisms underpinning ALD, particularly those underlying toxic effects of metabolic derivatives of alcohol on parenchymal and non-parenchymal hepatic cells leading to increased risk of alcohol-induced fibro-hepatocarcinogenesis, are still incompletely elucidated. In this review, we examined published scientific findings on how alcohol and its metabolic derivatives mount cellular attack on each hepatic cell and the underlying molecular mechanisms leading to disruption of core hepatic homeostatic functions which probably set the stage for the initiation and progression of ALD to fibro-hepatocarcinogenesis. We also brought to sharp focus, the complex and integrative role of transforming growth factor beta/small mothers against decapentaplegic/plasminogen activator inhibitor-1 and the mitogen activated protein kinase signaling nexus as well as their cross-signaling with toll-like receptor-mediated gut-dependent signaling pathways implicated in ALD and fibro-hepatocarcinogenesis. Looking into the future, it is hoped that these deliberations may stimulate new research directions on this topic and shape not only therapeutic approaches but also models for studying ALD and fibro-hepatocarcinogenesis.

Transfection with recombinant adenovirus vector expressing secreted frizzled related protein inhibits liver fibrosis in mice

AIM: To construct a recombinant adenovirus vector expressing secreted frizzled related protein (SFRP), and to assess the inhibitory effect of SFRP overexpression on experimental hepatic fibrosis (HF) in mice.

METHODS: Liposome-mediated transfection was used to introduce recombinant adenovirus pAd-Track-PPARγ2-CMV carrying the SFRP5 gene into liver cells from mice with CCl₄ induced HF to obtain recombinant adenovirus infected HF cells. Western blot, immunofluorescence microscopy and confocal laser microscopy were used to analyze the inhibitory effect of SFRP overexpression on experimental HF.

RESULTS: Cells infected with the recombinant adenovirus vector had higher expression of SFRP5 protein. Double immunofluorescence showed SFRP5 over expression inhibited the expression of α-smooth muscle actin (α-SMA) and fibroblast-specific protein-1 (FSP-1) in liver cells. Pathological examination revealed that SFRP5 over expression significantly reduced the occurrence of epithelial-mesenchymal transition (EMT) in liver cells (SFRP group vs control group, P < 0.05).

CONCLUSION: We have successfully constructed a recombinant adenovirus containing the SFRP5 gene, and it can effectively increase the expression of SFRP5 gene in mouse HF cells, thereby inhibiting the occurrence of EMT and HF.

New Approaches for Studying Alcoholic Liver Disease

Alcoholic liver disease (ALD) is major cause of chronic liver injury which results in liver fibrosis and cirrhosis. According to the surveillance report published by the National Institute on Alcohol Abuse and Alcoholism, liver cirrhosis is the 12th leading cause of death in the United States with 48 % of these deaths being attributed to excessive alcohol consumption. ALD includes a spectrum of disorders from simple steatosis to steatohepatitis, fibrosis, and hepatocellular carcinoma. Several mechanisms play a critical role in the pathogenesis of ALD. These include ethanol-induced oxidative stress and depletion of glutathione, pathological methionine metabolism, increased gut permeability and release of endotoxins into the portal blood, recruitment and activation of inflammatory cells including bone marrow-derived and liver resident macrophages (Kupffer cells). Chronic alcohol consumption results in liver damage and activation of hepatic stellate cells (HSCs) and myofibroblasts, leading to liver fibrosis. Here we discuss the current view on factors that are specific for different stages of ALD and those that regulate its progression, including cytokines and chemokines, alcohol-responsive intracellular signaling pathways, and transcriptional factors. We also review recent studies demonstrating that alcohol-mediated changes can be regulated on an epigenetic level, including microRNAs. Finally, we discuss the reversibility of liver fibrosis and inactivation of HSCs as a potential strategy for treating alcohol-induced liver damage.