Hepatic fibrogenesis in response to chronic liver injury: novel insights on the role of cell-to-cell interaction and transition

IL-17a promotes hepatocellular carcinoma by increasing FAP expression in hepatic stellate cells via activation of the STAT3 signaling pathway

Studies have shown that hepatic stellate cells (HSCs) and interleukin-17a (IL-17a) play important roles in liver tumorigenesis. In addition, fibroblast activation protein-α (FAP) has been shown to be a key regulator of hepatic stellate cell activation. In this study, in vivo and in vitro experiments were performed to verify the promoting effects of IL-17a administration, IL-17a overexpression, and FAP upregulation in HSCs on liver fibrosis and liver tumorigenesis. The cleavage under targets & release using nuclease (CUT&RUN) technique was used to verify the binding status of STAT3 to the FAP promoter. The in vitro studies showed that IL-17a activated HSCs and promoted HCC development and progression. FAP and IL-17a overexpression also activated HSCs, promoted HCC cell proliferation and migration, and inhibited HCC cell apoptosis. The in vivo studies suggested that IL-17a and FAP overexpression in HSCs facilitated liver tumor development and progression. The CUT&RUN results indicated that FAP expression was regulated by STAT3, which could bind to the FAP promoter region and regulate its transcription status. We concluded that IL-17a promoted HCC by increasing FAP expression in HSCs via activation of the STAT3 signaling pathway.

Neuroimmunomodulation of adrenoblockers during liver cirrhosis: modulation of hepatic stellate cell activity

The sympathetic nervous system and the immune system are responsible for producing neurotransmitters and cytokines that interact by binding to receptors; due to this, there is communication between these systems. Liver immune cells and nerve fibres are systematically distributed in the liver, and the partial overlap of both patterns may favour interactions between certain elements. Dendritic cells are attached to fibroblasts, and nerve fibres are connected via the dendritic cell-fibroblast complex. Receptors for most neuroactive substances, such as catecholamines, have been discovered on dendritic cells. The sympathetic nervous system regulates hepatic fibrosis through sympathetic fibres and adrenaline from the adrenal glands through the blood. When there is liver damage, the sympathetic nervous system is activated locally and systemically through proinflammatory cytokines that induce the production of epinephrine and norepinephrine. These neurotransmitters bind to cells through α-adrenergic receptors, triggering a cellular response that secretes inflammatory factors that stimulate and activate hepatic stellate cells. Hepatic stellate cells are key in the fibrotic process. They initiate the overproduction of extracellular matrix components in an active state that progresses from fibrosis to liver cirrhosis. It has also been shown that they can be directly activated by norepinephrine. Alpha and beta adrenoblockers, such as carvedilol, prazosin, and doxazosin, have recently been used to reverse CCl₄-induced liver cirrhosis in rodent and murine models.KEY MESSAGESNeurotransmitters from the sympathetic nervous system activate and increase the proliferation of hepatic stellate cells.Hepatic fibrosis and cirrhosis treatment might depend on neurotransmitter and hepatic nervous system regulation.Strategies to reduce hepatic stellate cell activation and fibrosis are based on experimentation with α-adrenoblockers.

CD24+LCN2+ liver progenitor cells in ductular reaction contributed to macrophage inflammatory responses in chronic liver injury

BACKGROUND

CD24+CK19+/CD24+SOX9+ resident liver cells are activated and expanded after chronic liver injury in a ductular reaction. However, the sources and functions of these cells in liver damage remain disputed.

RESULTS

The current study combined genetic lineage tracing with in vitro small-molecule-based reprogramming to define liver progenitor cells (LPCs) derived from hepatic parenchymal and non-parenchymal tissues. tdTom+ hepatocytes were isolated from ROSA26tdTomato mice following AAV8-Tbg-Cre-mediated recombination, EpCAM+ biliary epithelial cells (BECs) from wild-type intrahepatic bile ducts and ALB/GFP-EpCAM- cells were isolated from AlbCreERT/R26GFP mice. A cocktail of small molecules was used to convert the isolated cells into LPCs. These in vitro cultured LPCs with CD24 and SOX9 expression regained the ability to proliferate. Transcriptional profiling showed that the in-vitro cultured LPCs derived from the resident LPCs in non-parenchymal tissues expressed Lipocalin-2 (Lcn2) at high levels. Accordingly, endogenous Cd24a+Lcn2+ LPCs were identified by integration of sc-RNA-sequencing and pathological datasets of liver dysfunction which indicates that LPCs produced by ductular reactions might also originate from the resident LPCs. Transplantation of in-vitro cultured Cd24a+Lcn2+ LPCs into CCl4-induced fibrotic livers exacerbated liver damage and dysfunction, possibly due to LCN2-dependent macrophage inflammatory response.

CONCLUSIONS

CD24+LCN2+ LPCs constituted the expanding ductular reaction and contributed to macrophage-mediated inflammation in chronic liver damage. The current findings highlight the roles of LPCs from distinct origins and expose the possibility of targeting LPCs in the treatment of chronic hepatic diseases.

Diagnostic accuracy of apparent diffusion coefficient values combined with γ-glutamyl transpeptidase-to-platelet ratio parameters for predicting hepatitis B-related fibrosis

OBJECTIVES

The accuracy of non-invasive liver fibrosis diagnosis based on the apparent diffusion coefficient (ADC) value combined with the γ-glutamyl transpeptidase-to-platelet ratio (GPR) model to predict the stage of hepatitis B-related fibrosis has not been reported. This study aimed to evaluate the diagnostic efficacy of ADC value combined with GPR for liver fibrosis grading.

METHODS

The data of 180 patients with chronic hepatitis B (CHB) diagnosed by liver biopsy were analyzed. The ADC value, GPR, and their combination were assessed in different cirrhosis stages using receiver operating characteristic curve analysis to evaluate their value in diagnosing liver fibrosis.

RESULTS

We observed that liver fibrosis stages were inversely associated with ADC values (r=-0.691, P<0.001), and positively associated with GPR (r=0.502, P<0.001). The area under the curve for diagnostic efficacy of ADC values, GPR, and their combination for F≥2 liver fibrosis was 0.831, 0.749, and 0.858, respectively, and for F≥3 was 0.872, 0.771, and 0.903, respectively. The diagnostic cutoffs of the combination for each stage were -7.07, -12.21 and -37.75, respectively.

CONCLUSIONS

The combined diagnostic tool of ADC and GPR may improve the accuracy of hepatitis B-related liver fibrosis diagnosis, especially for F≥3.

Congenital aflatoxicosis, mal-detoxification genomics & ontogeny trigger immune-mediated Kotb disease biliary atresia variant: SANRA compliant review

Biliary atresia (BA) is the most common indication for pediatric liver transplantation. We describe The BA variant: Kotb disease. Liver tissue in the Kotb disease BA is massively damaged by congenital aflatoxicosis resulting in inflammation, adhesions, fibrosis, bile duct proliferation, scarring, cholestasis, focal syncytial giant cell transformation, and typical immune response involving infiltration by CD4+, CD8+, CD68+, CD14+, neutrophil infiltration, neutrophil elastase spill, heavy loads of aflatoxin B1, accelerated cirrhosis, disruption of p53 and GSTPi, and have null glutathione S transferase M1 (GSTM1). All their mothers are heterozygous for GSTM1. This inability to detoxify aflatoxicosis results in progressive inflammatory adhesions and obliterative cholangiopathy early in life. The typical disruption of both p53 and GSTPi causes loss of fidelity of hepatic regeneration. Hence, regeneration in Kotb disease BA typically promotes accelerated cirrhosis. The immune response in Kotb disease BA is for damage control and initiation of regeneration, yet, this friendly fire incurs massive structural collateral damage. The Kotb disease BA is about actual ongoing hepatic entrapment of aflatoxins with lack of ability of safe disposal due to child detoxification-genomics disarray. The Kotb disease BA is a product of the interaction of persistent congenital aflatoxicosis, genetic lack of GSTM1 detoxification, ontogenically impaired activity of other hepatic detoxification, massive neutrophil-elastase, immune-induced damage, and disturbed regeneration. Ante-natal and neonatal screening for aflatoxicosis, avoiding cord milking, and stringent control of aflatoxicosis content of human, poultry and live-stock feeds might prove effective for prevention, prompt diagnosis and management based on our recent understanding of its patho-genomics.

Transient Receptor Potential Vanilloid-1 (TRPV1) Alleviates Hepatic Fibrosis via TGF-β Signaling

Hepatic fibrosis is a major global health problem and considered a leading cause of liver-related morbidity and mortality worldwide. Although previous studies have suggested that transient receptor potential vanilloid-1 (TRPV1) is protective against cardiac and renal fibrosis, its functional role in hepatic fibrosis has remained elusive. Herein, we characterize the effects of TRPV1 on carbon tetrachloride- (CCl4-) induced mice, in vitro transforming growth factor-β- (TGF-β-) treated hepatic stellate cells (HSCs), and human fibrosis specimens. Finally, our results demonstrated the significant TRPV1 downregulation in human liver fibrosis tissues. Knocking out TRPV1 significantly increased the expression of various hepatic fibrosis markers, while the expression of these biomarkers declined markedly in capsaicin-activated mice. Moreover, our study revealed that knocking down TRPV1 would enhance the promotive effect of TGF-β on HSC proliferation, cell cycle, cell apoptosis, and ECM expression. Also, such promotive effect can be partially reversible by capsaicin, an exogenous activator of TRPV1. Collectively, the obtained data suggest that TRPV1 may alleviate CCl4-induced hepatic fibrosis and attenuate the effect of TGF-β on HSC activation, proliferation, and apoptosis, which overall implies that targeting TRPV1 channel activity may be an effective therapeutic strategy for treating hepatic fibrosis.

Effect of Quercetin on the fructose-activated human hepatic stellate cells, LX-2, an in-vitro study

BACKGROUND

Hepatic fibrosis is one of the main reasons for mortality in the world. Hepatic stellate cells (HSCs) activate during chronic liver injury, express more Transforming growth factor beta (TGF-β), Collagen1α (COLA1) and actin-alpha smooth muscle (αSMA) that lead to hepatic fibrosis. Quercetin is a flavonoid in vegetables and fruits that has shown hepatoprotective potential, but little is known about its effects on HSCs activation. In this study, we investigated the antifibrotic activity of Quercetin on fructose-activated human HSCs and its underlying mechanism in vitro.

METHODS

First, the human HSCs were treated with fructose (25 mM) for 48 h and then with Quercetin for 24 h. Total RNAs were extracted, reversely transcribed into cDNA, Quantitative Real-time PCR and western blot were performed.

RESULTS

The results showed that the levels of mRNA expression of TGF-β, αSMA, Collagen1 genes, and phosphorylated smad3 protein were significantly reduced in fructose-activated HSCs after treatment with Quercetin compared to fructose-activated HSCs.

CONCLUSION

Quercetin is effective in reducing the expression of fibrogenic genes in fructose-activated human HSCs through downregulation of the TGF-β/smad3 signaling pathway. Therefore, Quercetin possesses significant antifibrotic properties in hepatic fibrosis.

Quercetin Reduces Hepatic Fibrogenesis by Inhibiting TGF-β/Smad3 Signaling Pathway in LX-2 Cell Line

Background: Liver fibrosis has become one of the leading causes of morbidity and mortality in the world. Liver fibrosis progresses to cirrhosis and can eventually lead to hepatocellular carcinoma (HCC). During fibrogenesis, the hepatic stellate cells (HSCs) remain active and continuously produce more extracellular matrix (ECM). Quercetin, one of the main flavonoids in vegetables, has shown hepatoprotective potential, but its effects on liver fibrosis are not apparent. Objectives: In this study, we investigated the antifibrotic activity of quercetin following stimulation of TGF-β in the LX-2 cell line (a type of HSC-derived cell line) and its underlying mechanism in vitro. Methods: The LX-2 cells were treated with TGF-β1 (2 ng/mL) for 24 h. Next, the cells were treated with quercetin for 24 h, and the mRNA expression of α-smooth muscle actin (α-SMA), collagen1α1, and p-Smad3 protein levels were measured. Results: The results showed that the expression of α-SMA, collagen 1α1 (COL1α1) genes, and also the level of p-Smad3 protein in the presence of TGF-β increased significantly compared to the control group. Moreover, quercetin in concentrations of 75 and 100 μM inhibited TGF-β1-induced expression of α-SMA and COL1α1 genes and the p-Smad3 protein in LX-2 cells. Conclusions: We conclude that quercetin inhibits further activation of HSCs by inhibiting the TGF-β/Smad3 signaling pathway and reduces ECM accumulation during liver fibrosis in vitro, and may prevent the progression of liver fibrosis. Thus, the use of quercetin is suggested as a potential therapeutic agent in the treatment of liver fibrosis.

Levels of isoforms of fibronectin and α5/CD49e integrin on lymphocytes and in blood plasma in the conditions of chronic diffuse liver diseases

Chronic diffuse liver diseases are characterized by accumulation of complex inflammatory infiltrate in the liver tissues, blood, and lympha, and activation of the immune system. Leukocytes become involved in the area of inflammation after the activation of receptors of blood adhesia, particularly integrins and their ligands. Plasma lymphocytes quickly activate the function of integrins by changing their conformation, leading to high affinity and underlying the formation of strong stable connection between the components of extracellular matrix. A vitally important role in the process of liver fibrogenesis is performed by a pro-fibrogenicic protein fibronectin which induces the expresson of collagen genes and precedes the deposition of other components of matrix. The studies were conducted in the group of patients suffering from chronic diffuse liver diseases of non-viral etiology aged 28–60 years, n = 36 and in the group of 15 practically healthy volunteer donors aged 25 to 52 years without a history of liver diseases using the methods of flow cytofluorometry, immunoenzymatic analysis, and quantitative real-time polymerase chain reaction. The patients of the group with chronic diffuse liver diseases were observed to have statistically significant decrease in the concentration of plasmatic form of fibronectin measuring 27.6% compared with the control group. We determined increase in the concentration of cellular fibronectin in blood plasma of patients with the diseases on average accounting for 63.8% compared with the norm, and the highest increase in this parameter equaling 77.2% was seen in patients suffering from drug-induced hepatitis. Significant increase in the level of exposure of cellular FN on blood lymphocytes was determined in patients with chronic diffuse liver diseases, measuring 231.8%, whereas the level of plasmatic form of fibronectin in these cells was decreased (statistically unreliable). For α5-integrin subunit, we determined a 390.8% increase in the level of its exposure in blood lymphocytes in the surveyed groups compared with the control. Level of blood lymphocytes that express the cellular fibronectin significantly decreased by 140.1%. Statistical characteristics of diagnostic possibility of the parameters of the level of plasmatic and cellular fibronectin in blood, determined over the analysis of ROC-curves, demonstrated excellent informativeness of these tests. Analysis of the possibility of predicting the presence of pathology using the model of logistic regression revealed zero error of prediction and maximum efficiency of the tests: intensity of exposure of α5-integrin receptor on the surface of lymphocytes, intensity of exposure of plasmatic fibronectin on the surface of lymphocytes, intensity of exposure of cellular fibronectin on the surface of lymphocytes, concentration of plasmatic fibronectin in blood, concentration of cellular fibronectin in blood plasma. These parameters may be proposed for further surveys for developing serologic biomarkers based on the parameters for diagnostics of chronic diffuse liver diseases.

Review of parenteral nutrition-associated liver disease

Parenteral nutrition has been widely used in patients whose gastrointestinal tract is anatomically or physiologically unavailable for sufficient food intake. It has been considered lifesaving but is not without adverse effects. It has been proven to cause liver injury through different mechanisms. We present a review of parenteral nutrition-associated liver disease.

Tormentic acid inhibits hepatic stellate cells activation via blocking PI3K/Akt/mTOR and NF-κB signalling pathways

The present study was to investigate the inhibitory effect and underlying mechanism of Tormentic acid (TA) on hepatic stellate cells (HSCs). HSC-T6 cells were stimulated with Platelet-derived growth factor-BB (PDGF-BB) and TA, and then cell proliferation, apoptosis, inflammatory factor, and collagen-related indicators were detected. In order to elucidate the potential mechanism, the PI3K/Akt/mTOR and NF-κB signalling pathways were also detected. The results showed that TA treatment markedly inhibited PDGF-BB-stimulated HSC-T6 cell activation, as evidenced by the inhibition of cell proliferation, migration and colony formation, as well as the decreased expression of TGF-β and α-SMA. TA treatment caused a significant increase in the activity of lactate dehydrogenase and significantly promoted cell apoptosis. TA treatment significantly reduced aspartate aminotransferase, alanine aminotransferase and total bilirubin activity. Importantly, TA inhibited the expression of collagen type I and III, alleviating the excessive deposition of extracellular matrix (ECM). Further experiments showed that TA administration significantly inhibited the phosphorylation of PI3K, Akt, FAK and mTOR and the protein expression of P70S6K, indicating the inhibition of the PI3K/Akt/mTOR pathway. Moreover, treatment with TA markedly decreased the phosphorylation of IκBα, NF-κB p65 and IKKα/β, thereby blocking the NF-κB signal transduction. In summary, this study demonstrates that TA significantly inhibits HSC activation and promotes cell apoptosis via the inhibition of the PI3K/Akt/mTOR and NF-κB signalling pathways. SIGNIFICANCE OF THE STUDY: Tormentic acid (TA) could inhibit HSC activation and alleviate collagen-based ECM deposition, suggesting that TA exerted anti-hepatic fibrosis. Further mechanism research revealed that the inhibition of TA on HSC activation might be through blocking the PI3K/Akt/mTOR and NF-κB signalling pathways. These findings provided a new cue to understand the protective effect of TA against liver fibrosis, which may provide a potential nature medicine for the treatment of liver fibrosis.

Liver Fibrosis: Mechanistic Concepts and Therapeutic Perspectives

Liver fibrosis due to viral or metabolic chronic liver diseases is a major challenge of global health. Correlating with liver disease progression, fibrosis is a key factor for liver disease outcome and risk of hepatocellular carcinoma (HCC). Despite different mechanism of primary liver injury and disease-specific cell responses, the progression of fibrotic liver disease follows shared patterns across the main liver disease etiologies. Scientific discoveries within the last decade have transformed the understanding of the mechanisms of liver fibrosis. Removal or elimination of the causative agent such as control or cure of viral infection has shown that liver fibrosis is reversible. However, reversal often occurs too slowly or too infrequent to avoid life-threatening complications particularly in advanced fibrosis. Thus, there is a huge unmet medical need for anti-fibrotic therapies to prevent liver disease progression and HCC development. However, while many anti-fibrotic candidate agents have shown robust effects in experimental animal models, their anti-fibrotic effects in clinical trials have been limited or absent. Thus, no approved therapy exists for liver fibrosis. In this review we summarize cellular drivers and molecular mechanisms of fibrogenesis in chronic liver diseases and discuss their impact for the development of urgently needed anti-fibrotic therapies.

Bariatric Surgery in Cirrhotic Patients: Is It Safe?

Introduction

Ten percent of cirrhotic patients are known to have a high risk of postoperative complications. Ninety percent of bariatric patients suffer from non-alcoholic fatty liver disease (NAFLD), and 50% of them may develop non-alcoholic steatohepatitis (NASH) which can progress to cirrhosis. The aim of this study was to assess whether the presence of cirrhosis at the time of bariatric surgery is associated with an increased rate and severity of short- and long-term cirrhotic complications.

Methods

A cohort of 110 bariatric patients, between May 2003 and February 2018, who had undergone liver biopsy at the time of bariatric surgery were reassessed for histological outcome and divided into two groups based on the presence (C, n = 26) or absence (NC, n = 84) of cirrhosis. The NC group consisted of NASH (n = 49), NAFLD (n = 24) and non-NAFLD (n = 11) liver histology. Medical notes were retrospectively assessed for patient characteristics, development of 30-day postoperative complications, severity of complications (Clavien-Dindo (CD) classification) and length of stay. The C group was further assessed for long-term cirrhosis-related outcomes.

Results

The C group was older (52 years vs 43 years) and had lower BMI (46 kg/m2 vs 52 kg/m2) and weight (126 kg vs 145 kg) compared to the NC group (p < 0.05). The C group had significantly higher overall complication rate (10/26 vs 14/84, p < 0.05) and severity of complications (CD class ≥ III, 12% vs 7%, p < 0.05) when compared to the NC group. The length of stay was similar between the two groups (5 days vs 4 days). The C group had significant improvement in model end-stage liver disease scores (7 vs 6, p < 0.01) with median follow-up of 4.5 years (range 2–11 years). There were no long-term cirrhosis-related complications or mortality in our studied cohort (0/26).

Conclusion

Bariatric surgery in cirrhotic patients has a higher risk of immediate postoperative complications. Long-term cirrhosis-related complications or mortality was not increased in this small cohort. Preoperative identification of liver cirrhosis may be useful for risk stratification, optimisation and informed consent. Bariatric surgery in well-compensated cirrhotic patients may be used as an aid to improve long-term outcome.

Liver Progenitors and Adult Cell Plasticity in Hepatic Injury and Repair: Knowns and Unknowns

The liver is a complex organ performing numerous vital physiological functions. For that reason, it possesses immense regenerative potential. The capacity for repair is largely attributable to the ability of its differentiated epithelial cells, hepatocytes and biliary epithelial cells, to proliferate after injury. However, in cases of extreme acute injury or prolonged chronic insult, the liver may fail to regenerate or do so suboptimally. This often results in life-threatening end-stage liver disease for which liver transplantation is the only effective treatment. In many forms of liver injury, bipotent liver progenitor cells are theorized to be activated as an additional tier of liver repair. However, the existence, origin, fate, activation, and contribution to regeneration of liver progenitor cells is hotly debated, especially since hepatocytes and biliary epithelial cells themselves may serve as facultative stem cells for one another during severe liver injury. Here, we discuss the evidence both supporting and refuting the existence of liver progenitor cells in a variety of experimental models. We also debate the validity of developing therapies harnessing the capabilities of these cells as potential treatments for patients with severe and chronic liver diseases.

Insulin/high-density lipoprotein cholesterol ratio: A newly-discovered predictor of esophageal varices in patients with hepatitis C virus-related cirrhosis in the absence of diabetes mellitus

BACKGROUND/AIMS

Insulin resistance (IR) is closely linked with chronic hepatitis C virus (HCV) and its complications, particularly hepatic fibrosis. The aim of the present study was to investigate some biochemical markers that are potentially related to IR as predictors of esophageal varices (EV) in patients with compensated HCV cirrhosis who do not have diabetes or metabolic syndrome.

MATERIALS AND METHODS

One hundred subjects without diabetes with compensated HCV-related cirrhosis who did not fulfill the diagnostic criteria of metabolic syndrome were subjected to clinical, laboratory, ultrasonographic, and endoscopic assessments.

RESULTS

EV were evident in 73 patients with lower platelet counts and high-density lipoprotein cholesterol (HDL-C) levels. On the contrary, the fasting values of both insulin and glucose, the homeostatic model assessment for insulin resistance (HOMA-IR) score, and the bipolar diameter of the spleen of patients with EV were higher than those of other patients who were varices-free. Multivariate analysis confirmed insulin/HDL-C ratio (P=0.01) and HOMA-IR score (P=0.039) as predictors for the presence of varices. The best cut-off values above which the risk of the latter occurrence increased were 0.147 (sensitivity 89%) and 2.24 (sensitivity 72.6%) for both predictors, respectively.

CONCLUSION

The present study recorded two valid predictors of HCV-related EV: HOMA-IR score and insulin/HDL-C ratio. The latter is more sensitive and is likely more convenient in the case of individuals without diabetes. The validity of two IR-related predictors in the absence of metabolic syndrome confirmed the suggestion that the mechanism of IR-related HCV is different from that of the traditional metabolic syndrome.

A critical role of autophagy in regulating the mesenchymal transition of ductular cells in liver cirrhosis

Our previous studies have shown that autophagy mediates the link between ductular reaction (DR) and liver cirrhosis. Whether the subsequent fibrogenic response is regulated by increased autophagy in DR remains unclear. Here, using both human liver specimens and a rat model of liver cirrhosis induced by 2-acetylaminofluorene (AAF) and carbon tetrachloride (CCL4), we explored the involvement of autophagy in regulating mesenchymal transition of ductular cells. Ductular cells from AAF/CCL4 livers exhibited increased autophagy compared to those of normal livers. These cells showed morphological and functional characteristics of mesenchymal cells. Blocking autophagy using bafilomycin A1 or siRNA targeting ATG7 reduced the expression of mesenchymal markers in these ductular cells from AAF/CCL4 livers, indicating a role for autophagy in regulating the mesenchymal phenotype of ductular cells. Furthermore, we show that the mesenchymal transition in DR requires the activation of transforming growth factor-β (TGF-β) signaling in an autophagy-dependent manner. Importantly, in cirrhotic human livers, ductular cells that are positive for LC3B also showed increased expression of TGF-β and fibroblast-specific protein-1. Our data suggest activation of autophagy in ductular cells, and also demonstrate that it is required for the mesenchymal transition during the DR, processes that are critically involved in the pathogenesis of cirrhosis.

Notch Inhibition Promotes Differentiation of Liver Progenitor Cells into Hepatocytes via sox9b Repression in Zebrafish

Liver regeneration after most forms of injury is mediated through the proliferation of hepatocytes. However, when hepatocyte proliferation is impaired, such as during chronic liver disease, liver progenitor cells (LPCs) arising from the biliary epithelial cell (BEC) compartment can give rise to hepatocytes to mediate hepatic repair. Promotion of LPC-to-hepatocyte differentiation in patients with chronic liver disease could serve as a potentially new therapeutic option, but first requires the identification of the molecular mechanisms driving this process. Notch signaling has been identified as an important signaling pathway promoting the BEC fate during development and has also been implicated in regulating LPC differentiation during regeneration. SRY-related HMG box transcription factor 9 (Sox9) is a direct target of Notch signaling in the liver, and Sox9 has also been shown to promote the BEC fate during development. We have recently shown in a zebrafish model of LPC-driven liver regeneration that inhibition of Hdac1 activity through MS-275 treatment enhances sox9b expression in LPCs and impairs LPC-to-hepatocyte differentiation. Therefore, we hypothesized that inhibition of Notch signaling would promote LPC-to-hepatocyte differentiation by repressing sox9b expression in zebrafish. We ablated the hepatocytes of Tg(fabp10a:CFP-NTR) larvae and blocked Notch activation during liver regeneration through treatment with γ-secretase inhibitor LY411575 and demonstrated enhanced induction of Hnf4a in LPCs. Alternatively, enhancing Notch signaling via Notch3 intracellular domain (N3ICD) overexpression impaired Hnf4a induction. Hepatocyte ablation in sox9b heterozygous mutant embryos enhanced Hnf4a induction, while BEC-specific Sox9b overexpression impaired LPC-to-hepatocyte differentiation. Our results establish the Notch-Sox9b signaling axis as inhibitory to LPC-to-hepatocyte differentiation in a well-established in vivo LPC-driven liver regeneration model.

Hepatocyte-Specific β-Catenin Deletion During Severe Liver Injury Provokes Cholangiocytes to Differentiate Into Hepatocytes

Liver regeneration after injury is normally mediated by proliferation of hepatocytes, although recent studies have suggested biliary epithelial cells (BECs) can differentiate into hepatocytes during severe liver injury when hepatocyte proliferation is impaired. We investigated the effect of hepatocyte-specific β-catenin deletion in recovery from severe liver injury and BEC-to-hepatocyte differentiation. To induce liver injury, we administered choline-deficient, ethionine-supplemented (CDE) diet to three different mouse models, the first being mice with deletion of β-catenin in both BECs and hepatocytes (Albumin-Cre; Ctnnb1^flox/flox mice). In our second model, we performed hepatocyte lineage tracing by injecting Ctnnb1^flox/flox ; Rosa-stop^flox/flox -EYFP mice with the adeno-associated virus serotype 8 encoding Cre recombinase under the control of the thyroid binding globulin promoter, a virus that infects only hepatocytes. Finally, we performed BEC lineage tracing via Krt19-Cre^ERT ; Rosa-stop^flox/flox -tdTomato mice. To observe BEC-to-hepatocyte differentiation, mice were allowed to recover on normal diet following CDE diet-induced liver injury. Livers were collected from all mice and analyzed by quantitative real-time polymerase chain reaction, western blotting, immunohistochemistry, and immunofluorescence. We show that mice with lack of β-catenin in hepatocytes placed on the CDE diet develop severe liver injury with impaired hepatocyte proliferation, creating a stimulus for BECs to differentiate into hepatocytes. In particular, we use both hepatocyte and BEC lineage tracing to show that BECs differentiate into hepatocytes, which go on to repopulate the liver during long-term recovery. Conclusion: β-catenin is important for liver regeneration after CDE diet-induced liver injury, and BEC-derived hepatocytes can permanently incorporate into the liver parenchyma to mediate liver regeneration.

Junctional adhesion molecules JAM-B and JAM-C promote autoimmune-mediated liver fibrosis in mice

Fibrosis remains a serious health concern in patients with chronic liver disease. We recently reported that chemically induced chronic murine liver injury triggers increased expression of junctional adhesion molecules (JAMs) JAM-B and JAM-C by endothelial cells and de novo synthesis of JAM-C by hepatic stellate cells (HSCs). Here, we demonstrate that biopsies of patients suffering from primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) or autoimmune hepatitis (AIH) display elevated levels of JAM-C on portal fibroblasts (PFs), HSCs, endothelial cells and cholangiocytes, whereas smooth muscle cells expressed JAM-C constitutively. Therefore, localization and function of JAM-B and JAM-C were investigated in three mouse models of autoimmune-driven liver inflammation. A PBC-like disease was induced by immunization with 2-octynoic acid-BSA conjugate, which resulted in the upregulation of both JAMs in fibrotic portal triads. Analysis of a murine model of PSC revealed a role of JAM-C in PF cell-cell adhesion and contractility. In mice suffering from AIH, endothelial cells increased JAM-B level and HSCs and capsular fibroblasts became JAM-C-positive. Most importantly, AIH-mediated liver fibrosis was reduced in JAM-B^-/- mice or when JAM-C was blocked by soluble recombinant JAM-C. Interestingly, loss of JAM-B/JAM-C function had no effect on leukocyte infiltration, suggesting that the well-documented function of JAMs in leukocyte recruitment to inflamed tissue was not effective in the tested chronic models. This might be different in patients and may even be complicated by the fact that human leukocytes express JAM-C. Our findings delineate JAM-C as a mediator of myofibroblast-operated contraction of the liver capsule, intrahepatic vasoconstriction and bile duct stricture. Due to its potential to interact heterophilically with endothelial JAM-B, JAM-C supports also HSC/PF mural cell function. Together, these properties allow JAM-B and JAM-C to actively participate in vascular remodeling associated with liver/biliary fibrosis and suggest them as valuable targets for anti-fibrosis therapies.

Pathophysiology of liver fibrosis and the methodological barriers to the development of anti-fibrogenic agents

Liver fibrosis and cirrhosis resulting from long-standing liver damage represents a major health care burden worldwide. To date, there is no anti-fibrogenic agent available, making liver transplantation the only curative treatment for decompensated cirrhotic liver disease. Liver fibrosis can result from different underlying chronic liver disease, such as chronic viral infection, excessive alcohol consumption, fatty liver disease or autoimmune liver diseases. It is becoming increasingly recognised that as a result from different pathogenic mechanisms liver fibrosis must be considered as many different diseases for which individual treatment strategies need to be developed. Moreover, the pathogenic changes of both liver architecture and vascularisation in cirrhotic livers, as well as the lack of "true-to-life" in vitro models have impeded the development of an effective anti-fibrogenic drug. Thus, in order to identify an efficient anti-fibrogenic compound, novel in-vitro models mimicking the interplay between pro-fibrogenic cell populations, immune cells and, importantly, the extracellular matrix need to be developed.

Decellularized tongue tissue as an in vitro model for studying tongue cancer and tongue regeneration

The decellularization of tissues or organs provides an efficient strategy for preparing functional scaffolds for tissue engineering. The microstructures of native extracellular matrices and biochemical compositions retained in the decellularized matrices provide tissue-specific microenvironments for anchoring cells. Here, we report the tongue extracellular matrix (TEM), which showed favorable cytocompatibility for normal tongue-derived cells and tongue squamous cell carcinoma (TSCC) cells under static or stirring culture conditions. Our results show that TEM retained tongue-specific integrated microstructures and abundant matrix components, which offer mechanical support and spatial signals for regulating cell behavior and function. Reconstructed TSCC by TEM presented characteristics resembling clinical TSCC histopathology, suggesting the possibility for TSCC research. In addition, TEM might be capable of guiding tongue-derived cells to the niche, benefiting cell survival, proliferation and differentiation.

STATEMENT OF SIGNIFICANCE

In this study, we prepared decellularized tongue extracellular matrix (TEM) and evaluated the possibility for tongue squamous cell carcinoma (TSCC) research and tongue regeneration. TEM has six irreplaceable advantages: (1) tongue-specific intricate structures of TEM, which offer mechanical support for the cells; (2) abundant matrix components and spatial signals benefiting for cell attachment, survival, differentiation, and long-term viability of the highly functional phenotypes of tongue cells or TSCC cells; (3) reconstructed TSCC by TEM exhibited tumor heterogeneity, extremely resembling clinical TSCC histopathology; (4) ideal model to evaluate TSCC movement mode; (5) guiding tongue-derived cells to the site-appropriate niche; and (6) the possibility for static or stirred cell culture. These properties might be considered in TSCC research or tongue regeneration.

Non-alcoholic fatty liver disease, to struggle with the strangle: Oxygen availability in fatty livers

Nonalcoholic fatty liver diseases (NAFLD) is one of the most common chronic liver disease in Western countries. Oxygen is a central component of the cellular microenvironment, which participate in the regulation of cell survival, differentiation, functions and energy metabolism. Accordingly, sufficient oxygen supply is an important factor for tissue durability, mainly in highly metabolic tissues, such as the liver. Accumulating evidence from the past few decades provides strong support for the existence of interruptions in oxygen availability in fatty livers. This outcome may be the consequence of both, impaired systemic microcirculation and cellular membrane modifications which occur under steatotic conditions. This review summarizes current knowledge regarding the main factors which can affect oxygen supply in fatty liver.

Nonalcoholic fatty liver disease and bariatric surgery: a comprehensive review

CONTEXT AND OBJECTIVE:

Nonalcoholic fatty liver disease (NAFLD) has been increasingly diagnosed worldwide and is now recognized as a source of public health concern. It comprises a wide spectrum of histological features that range from simple steatosis to severe forms of fibrosis, steatohepatitis and even cirrhosis. The impact of bariatric surgery on the course of NAFLD in individuals with obesity has been extensively studied.

DESIGN AND SETTING:

Narrative review; public university hospital.

METHODS:

A comprehensive review was conducted based on an online search on the electronic databases MEDLINE and LILACS using the MeSH terms "fatty liver" and "bariatric surgery".

RESULTS:

The exact mechanisms that lead to improvement in NAFLD following bariatric surgery are not completely understood. Since Roux-en-Y gastric bypass (RYGB) is the bariatric surgical procedure most performed worldwide, it is also the one from which the effects on NAFLD have been most studied, although there is also consistent evidence regarding the effects from gastric banding, sleeve gastrectomy and biliopancreatic diversions.

CONCLUSION:

According to the currently available evidence, bariatric surgery leads to significant improvement in NAFLD. Further research, especially by means of randomized controlled trials enrolling larger cohorts of individuals, is needed to determine the optimal procedure for this group of subjects.

Fibronectin expression is critical for liver fibrogenesis in vivo and in vitro

Increased fibronectin (FN) expression has an important role during liver fibrosis. The present study examined FN expression in rats subjected to carbon tetrachloride (CCl4)‑induced liver fibrosis. In addition, the potential mechanisms underlying fibrogenesis were investigated by exposing hepatic stellate cells (HSCs) to transforming growth factor‑β (TGF‑β), which is a known inducer of myofibroblastic transformation of HSCs. Briefly, a rat model of liver fibrosis was created by administering intraperitoneal injections of CCl4. Furthermore, HSC‑T6 cells were stimulated with increasing doses of recombinant TGF‑β over 24 h. Hepatic fibrosis gradually increased following CCl4 administration in vivo. Western blotting and immunohistochemistry demonstrated that fibronectin (FN), TGF‑β and α‑smooth muscle actin (SMA) expression was increased following CCl4 injection, and the maximum expression levels were observed at 8 weeks. Once CCl4 treatment had been terminated, the expression levels of FN, TGF‑β and α‑SMA progressively declined to near baseline levels. Western blotting and quantitative polymerase chain reaction demonstrated that FN expression was gradually increased in response to TGF‑β‑stimulation of HSCs; maximum expression was achieved 12 h post‑treatment (P<0.01 vs. the baseline). In conclusion, these findings indicated that FN expression is an early and progressive event that occurs during liver fibrogenesis in vivo and in vitro.

LPS-induced TNF-α factor mediates pro-inflammatory and pro-fibrogenic pattern in non-alcoholic fatty liver disease

Lipopolysaccharide (LPS) is currently considered one of the major players in non-alcoholic fatty liver disease (NAFLD) pathogenesis and progression. Here, we aim to investigate the possible role of LPS-induced TNF-α factor (LITAF) in inducing a pro-inflammatory and pro-fibrogenic phenotype of non-alcoholic steatohepatitis (NASH).We found that children with NAFLD displayed, in different liver-resident cells, an increased expression of LITAF which correlated with histological traits of hepatic inflammation and fibrosis. Total and nuclear LITAF expression increased in mouse and human hepatic stellate cells (HSCs). Moreover, LPS induced LITAF-dependent transcription of IL-1β, IL-6 and TNF-α in the clonal myofibroblastic HSC LX-2 cell line, and this effect was hampered by LITAF silencing. We showed, for the first time in HSCs, that LITAF recruitment to these cytokine promoters is LPS dependent. However, preventing LITAF nuclear translocation by p38MAPK inhibitor, the expression of IL-6 and TNF-α was significantly reduced with the aid of p65NF-ĸB, while IL-1β transcription exclusively required LITAF expression/activity. Finally, IL-1β levels in plasma mirrored those in the liver and correlated with LPS levels and LITAF-positive HSCs in children with NASH.In conclusion, a more severe histological profile in paediatric NAFLD is associated with LITAF over-expression in HSCs, which in turn correlates with hepatic and circulating IL-1β levels outlining a panel of potential biomarkers of NASH-related liver damage. The in vitro study highlights the role of LITAF as a key regulator of the LPS-induced pro-inflammatory pattern in HSCs and suggests p38MAPK inhibitors as a possible therapeutic approach against hepatic inflammation in NASH.

Macrophage Depletion Attenuates Extracellular Matrix Deposition and Ductular Reaction in a Mouse Model of Chronic Cholangiopathies

Chronic cholangiopathies, such as primary and secondary sclerosing cholangitis, are progressive disease entities, associated with periportal accumulation of inflammatory cells, encompassing monocytes and macrophages, peribiliary extracellular matrix (ECM) deposition and ductular reaction (DR). This study aimed to elucidate the relevance of macrophages in the progression of chronic cholangiopathies through macrophage depletion in a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) mouse model. One group of mice received a single i.p. injection of Clodronate encapsulated liposomes (CLOLipo) at day 7 of a 14 day DDC treatment, while control animals were co-treated with PBSLipo instead. Mice were sacrificed after 7 or respectively 14 days of treatment for immunohistochemical assessment of macrophage recruitment (F4/80), ECM deposition (Sirius Red, Laminin) and DR (CK19). Macrophage depletion during a 14 day DDC treatment resulted in a significant inhibition of ECM deposition. Porto-lobular migration patterns of laminin-rich ECM and ductular structures were significantly attenuated and a progression of DR was effectively inhibited by macrophage depletion. CLOLipo co-treatment resulted in a confined DR to portal regions without amorphous cell clusters. This study suggests that therapeutic options selectively directed towards macrophages might represent a feasible treatment for chronic cholestatic liver diseases.

Piceatannol increases the expression of hepatocyte growth factor and IL-10 thereby protecting hepatocytes in thioacetamide-induced liver fibrosis

Piceatannol is a polyphenolic analog of resveratrol that selectively inhibits the non-receptor tyrosine kinase-Syk. This study investigates the potential ability of piceatannol to attenuate liver fibrosis and protect hepatocytes from injury. Thioacetamide was injected in adult male mice (100 mg/kg, i.p., 3 times/week) for 8 weeks. Piceatannol (1 or 5 mg/kg per day) was administered by oral gavage during the last 4 weeks. Liver function biomarkers, tissue malondialdehyde (MDA), cytokeratin-18 (CK18), hepatocyte growth factor (HGF), and interleukin-10 (IL-10) were measured. Necroinflammation, fibrosis, expression of transforming growth factor (TGF)-β1, and α-smooth muscle actin (SMA) were scored by histopathological examination and immunohistochemistry. Obtained results showed ability of piceatannol (1 mg/kg) to restore liver function and reduce inflammation. It significantly (p < 0.001) reduced MDA, CK18, TGF-β1, and α-SMA expression, and increased HGF and IL-10. It can be concluded that piceatannol at low dose can inhibit TGF-β1 induced hepatocytes apoptosis and exerts an anti-inflammatory effect attenuating fibrosis progression.

Mechanisms of adaptation of the hepatic vasculature to the deteriorating conditions of blood circulation in liver cirrhosis

PubMed, EMBASE, Orphanet, MIDLINE, Google Scholar and Cochrane Library were searched for articles published between 1983 and 2015. Relevant articles were selected by using the following terms: “Liver cirrhosis”, “Endothelial dysfunction”, “Sinusoidal remodeling”, “Intrahepatic angiogenesis” and “Pathogenesis of portal hypertension”. Then the reference lists of identified articles were searched for other relevant publications as well. Besides gross hepatic structural disorders related to diffuse fibrosis and formation of regenerative nodules, the complex morphofunctional rearrangement of the hepatic microvascular bed and intrahepatic angiogenesis also play important roles in hemodynamic disturbances in liver cirrhosis. It is characterized by endothelial dysfunction and impaired paracrine interaction between activated stellate hepatocytes and sinusoidal endotheliocytes, sinusoidal remodeling and capillarization, as well as development of the collateral microcirculation. In spite of the fact that complex morphofunctional rearrangement of the hepatic microvascular bed and intrahepatic angiogenesis in liver cirrhosis are the compensatory-adaptive reaction to the deteriorating conditions of blood circulation, they contribute to progression of disease and development of serious complications, in particular, related to portal hypertension.

Comparative study of antifibrotic activity of some magnesium-containing supplements on experimental liver toxicity. Molecular study

INTRODUCTION

Liver fibrosis is the excessive accumulation of extracellular matrix (ECM) proteins including collagen that occurs in most types of chronic liver diseases. This study aimed to investigate and compare the therapeutic efficacy of different magnesium (Mg)-containing supplements (formulations A, B, and C) on carbon tetrachloride (CCl₄)-induced liver fibrosis in rats.

METHODS

Liver fibrosis was induced by intraperitoneal injection of rats with CCl₄ (1:1 in olive oil, 2 mL/kg, three times/week) for 4 weeks, and then rats were orally treated with different Mg-containing supplements (formulations A, B, and C) once daily for another one month. Liver fibrosis was quantified by evaluation of expressions of Collagen I, transforming growth factor β-1 (TGFβ1), platelet-derived growth factor-C (PDGF-C), nuclear factor kappa-β (NF-κβ), and measurement of hepatic collagen (hydroxyproline) level. Also, malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH) level, superoxide dismutase (SOD), and glutathione-S-transferase (GST) activities were estimated.

RESULTS

CCl₄ administration significantly elevated expressions of the studied genes, hepatic hydroxyproline, MDA, and NO levels and caused depletion of GSH level, decreased SOD, and GST activities when compared with those of their corresponding control, p < 0.05. All magnesium supplements significantly inhibited expressions of the studied genes and attenuated the hepatic hydroxyproline level as compared with those of CCl₄-treated group_; p < 0.05; for NF-κβ, the highest inhibition was by formulations B and C. Regarding Collagen I, TGFβ1, and hepatic hydroxyproline content, the highest inhibition was by Formulation C, and Formulation A revealed highest inhibition for PDGF-C. All magnesium supplements revealed normalization of oxidant and antioxidants parameters. Histopathological examination supports the biochemical and molecular findings.

CONCLUSION

Mg supplements were effective in the treatment of hepatic CCl₄-induced fibrosis-rat model.

Murine junctional adhesion molecules JAM-B and JAM-C mediate endothelial and stellate cell interactions during hepatic fibrosis

Classical junctional adhesion molecules JAM-A, JAM-B and JAM-C influence vascular permeability, cell polarity as well as leukocyte recruitment and immigration into inflamed tissue. As the vasculature becomes remodelled in chronically injured, fibrotic livers we aimed to determine distribution and role of junctional adhesion molecules during this pathological process. Therefore, livers of naïve or carbon tetrachloride-treated mice were analyzed by immunohistochemistry to localize all 3 classical junctional adhesion molecules. Hepatic stellate cells and endothelial cells were isolated and subjected to immunocytochemistry and flow cytometry to determine localization and functionality of JAM-B and JAM-C. Cells were further used to perform contractility and migration assays and to study endothelial tubulogenesis and pericytic coverage by hepatic stellate cells. We found that in healthy tissue, JAM-A was ubiquitously expressed whereas JAM-B and JAM-C were restricted to the vasculature. During fibrosis, JAM-B and JAM-C levels increased in endothelial cells and JAM-C was de novo generated in myofibroblastic hepatic stellate cells. Soluble JAM-C blocked contractility but increased motility in hepatic stellate cells. Furthermore, soluble JAM-C reduced endothelial tubulogenesis and endothelial cell/stellate cell interaction. Thus, during liver fibrogenesis, JAM-B and JAM-C expression increase on the vascular endothelium. More importantly, JAM-C appears on myofibroblastic hepatic stellate cells linking them as pericytes to JAM-B positive endothelial cells. This JAM-B/JAM-C mediated interaction between endothelial cells and stellate cells stabilizes vessel walls and may control the sinusoidal diameter. Increased hepatic stellate cell contraction mediated by JAM-C/JAM-C interaction may cause intrahepatic vasoconstriction, which is a major complication in liver cirrhosis.

Total Parenteral Nutrition-Induced Cholestasis: Prevention and Management

When cholestasis occurs in patients receiving total parenteral nutrition, it is the result of many pathogenic pathways converging on the hepatic acinus. The result may be a temporary rise in liver function tests. The resulting fibrosis, portal hypertension, and jaundice are hallmarks of type 3 intestinal-associated liver disease to which children are more susceptible than adults. The key to prevention is in identifying high-risk scenarios, meticulous monitoring, and personalized prescription of parenteral nutrition solutions combined with an active approach in reducing the impact of inflammatory events when they occur by prompt use of antibiotics and line locks.

Treating morbid obesity in cirrhosis: A quest of holy grail

The problem of obesity is increasing worldwide in epidemic proportions; the situation is similarly becoming more common in patients with cirrhosis which negatively affect the prognosis of disease and also makes liver transplantation difficult especially in the living donor liver transplantation setting where low graft to recipient weight ratio negatively affects survival. Treatment of obesity is difficult in cirrhosis due to difficulty in implementation of lifestyle measures, limited data on safety of anti-obesity drugs and high risk of surgery. Currently approved anti-obesity drugs have limited data in patients with cirrhosis. Bariatric surgery remains an option in selected compensated cirrhotic patients. Endoscopic interventions for obesity are emerging and are quite promising in patients with cirrhosis as these are minimally invasive. In present review, we briefly discuss various modalities of weight reduction in obese patients and their applicability in patients with cirrhosis.

Resveratrol attenuates the progress of liver fibrosis via the Akt/nuclear factor-κB pathways

Liver fibrosis is a wound-healing response to chronic liver injury that results in the accumulation of extracellular matrix proteins. It eventually leads to cirrhosis of the liver and liver failure, and it is a critical threat to the health and lives of patients with chronic liver diseases. No effective treatment is currently available. Resveratrol is a polyphenol with antioxidant, anti‑cancer and anti‑inflammatory properties. It has been reported that resveratrol prevents liver fibrosis, possibly by inhibiting NF‑κB activation. The present study investigated the mechanisms by which resveratrol prevented liver fibrosis, focusing on the possible involvement of the NF‑κB pathway. Mice with carbon tetrachloride (CCl4)‑induced liver fibrosis were treated with various concentrations of resveratrol. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and tumor necrosis factor (TNF)‑α were detected by ELISAs. Expression of α‑smooth muscle actin (α‑SMA), collagen I, inhibitor of NF‑κB (IκB) and NF‑κB were detected by western blot analysis. In addition, the present study examined the effects of resveratrol on the expression of fibrosis markers in LX‑2 cells. Western blot analysis was further used to detect the levels of Akt and phosphorylated Akt, as well as the nuclear levels of IκB, phosphorylated IκB and NF‑κB p65. The expression of α‑SMA in resveratrol‑treated LX‑2 cells was detected by immunofluorescence and flow cytometry, which demonstrated that resveratrol decreased the expression of α‑SMA in LX‑2 cells. Resveratrol also decreased CCl4‑induced upregulation of serum AST, ALT, TNF‑α, α‑SMA and collagen I. Finally, resveratrol prevented the activation of NF‑κB and Akt. The results of the present study therefore indicated that resveratrol attenuates liver fibrosis via the Akt/NF-κB pathways.

Differentiation of Bone Marrow: Derived Mesenchymal Stem Cells into Hepatocyte-like Cells

Cirrhosis is the end-stage liver fibrosis, whereby normal liver architecture is disrupted by fibrotic bands, parenchymal nodules and vascular distortion. Portal hypertension and hepatocyte dysfunction are the end results and give rise to major systemic complications and premature death. Mesenchymal stem cells (MSC) have the capacity of self-renew and to give rise to cells of various lineages, so MSC can be isolated from bone marrow (BM) and induced to differentiate into hepatocyte-like cells. MSC were induced to differentiate into hepatocyte-like cells by hepatotic growth factor (HGF) and fibroblast growth factor-4 (FGF-4). Differentiated cells were examined for the expression of hepatocyte-specific markers and hepatocyte functions. MSC were isolated. Flow cytometry analysis showed that they expressed the MSC-specific markers, reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated that MSC expressed the hepatocyte-specific marker cytokeratin 18 (CK-18) following hepatocyte induction. This study demonstrates that BM-derived-MSC can differentiate into functional hepatocyte-like cells following the induction of HGF and FGF-4. MSC can serve as a favorable cell source for tissue engineering in the treatment of liver disease.

A novel technique for simultaneous whole-body and multi-organ decellularization: umbilical artery catheterization as a perfusion-based method in a sheep foetus model

The aim of this study was to develop a method to generate multi-organ acellular matrices. Using a foetal sheep model have developed a method of systemic pulsatile perfusion via the umbilical artery which allows for simultaneous multi-organ decellularization. Twenty sheep foetuses were systemically perfused with Triton X-100 and sodium dodecyl sulphate. Following completion of the whole-body decellularization, multiple biopsy samples were taken from different parts of 21 organs to ascertain complete cell component removal in the preserved extracellular matrices. Both the natural and decellularized organs were subjected to several examinations. The samples were obtained from the skin, eye, ear, nose, throat, cardiovascular, respiratory, gastrointestinal, urinary, musculoskeletal, central nervous and peripheral nervous systems. The histological results depicted well-preserved extracellular matrix (ECM) integrity and intact vascular structures, without any evidence of residual cellular materials, in all decellularized bioscaffolds. Scanning electron microscope (SEM) and biochemical properties remained intact, similar to their age-matched native counterparts. Preservation of the collagen structure was evaluated by a hydroxyproline assay. Dense organs such as bone and muscle were also completely decellularized, with a preserved ECM structure. Thus, as shown in this study, several organs and different tissues were decellularized using a perfusion-based method, which has not been previously accomplished. Given the technical challenges that exist for the efficient generation of biological scaffolds, the current results may pave the way for obtaining a variety of decellularized scaffolds from a single donor. In this study, there have been unique responses to the single acellularization protocol in foetuses, which may reflect the homogeneity of tissues and organs in the developing foetal body.

Increased Autophagy Markers Are Associated with Ductular Reaction during the Development of Cirrhosis

Autophagy is a regulatory pathway in liver fibrosis. We investigated the roles of autophagy in human cirrhotic livers. Cirrhotic and noncirrhotic liver tissues were obtained from patients with hepatocellular carcinoma, and liver tissues from live donors served as control. Patients with cirrhotic livers had significantly increased levels of various essential autophagy-related genes compared with noncirrhotic livers. In addition, colocalization of autophagy marker microtubule-associated protein 1 light chain 3B (LC3B) with lysosome-associated membrane protein-1, increased levels of lysosome-associated membrane protein-2, and increased maturation of lysosomal cathepsin D were observed in cirrhotic livers. By using dual-immunofluorescence staining, we demonstrated that increased LC3B was located mainly in the cytokeratin 19-labeled ductular reaction (DR) in human cirrhotic livers and in an experimental cirrhosis induced by 2-acetylaminofluorene (AAF) with carbon tetrachloride (CCl4), indicating a conserved response to chronic liver damage. Furthermore, an AAF/CCl4-mediated increase in DR and fibrosis were attenuated after chloroquine treatment, suggesting that the autophagy-lysosome pathway was essential for AAF/CCl4-induced DR-fibrosis. In conclusion, we demonstrated that increased autophagy marker positively correlated with DR during the development of cirrhosis. Therefore, targeting autophagy may hold therapeutic value for liver cirrhosis.

Hepatic progenitor cells in children with chronic hepatitis C: correlation with histopathology, viremia, and treatment response

OBJECTIVE

Hepatic progenitor cells (HPCs) are bipotential stem cells that can differentiate towards the hepatocytic and cholangiocytic lineages. Many studies have investigated HPCs in adults with hepatitis C virus infection; however, none has been carried out in the pediatric population. Therefore, this work aimed to investigate HPCs expansion in children with chronic hepatitis C (CHC) and its correlation with histopathology, viremia, and treatment response.

PATIENTS AND METHODS

Eighty children with CHC, 73 of whom received interferon-based therapy, were recruited. Sections of their liver biopsies were prepared for immunostaining of HPCs using cytokeratin-7 antibody.

RESULTS

HPCs were expanded in most children (81.3%) with CHC. Expansion occurred in two forms: intraparenchymal isolated hepatic progenitor cell form and periportal ductular reaction form. There was a significant increase in HPCs expansion in higher stages of fibrosis (50, 81.8, and 100% in no, mild, and moderate fibrosis, respectively, with P=0.029). Also, HPCs expansion increased with increased grade of necroinflammatory activity (0, 77.8, 81.8, and 100%, in no, minimal, mild, and moderate activity, respectively), although this was statistically insignificant. Moreover, a significant positive correlation was found between the isolated hepatic progenitor cell number and ductular reaction grade (r=0.755, P<0.0001), and both were significantly correlated with the level of viremia and the grade of necroinflammatory activity. Finally, HPCs expansion was not related to the treatment response.

CONCLUSION

The relationship of HPCs with both the severity of hepatitis and the stage of fibrosis may be because of a role of HPCs in their pathogenesis.

Antifibrotic effects of luteolin on hepatic stellate cells and liver fibrosis by targeting AKT/mTOR/p70S6K and TGFβ/Smad signalling pathways

BACKGROUND & AIMS

Luteolin has been reported to exert antifibrogenic effects in CCl4 -induced hepatic fibrosis in mice. However, limited information is available on the cellular and molecular events responsible for this effect. This study focused on the action of luteolin on hepatic stellate cells (HSCs) and the relevant signalling molecules and pathways as well as the antifibrotic efficacy in multiple models of fibrosis.

METHODS

The in vitro effect of luteolin on rat HSCs and HSC-T6 cells was assessed using proliferation assays, invasion chamber, quantitative real-time PCR analysis and Western blotting. The in vivo effect of luteolin on progression of fibrosis was assessed in three experimental rat models induced by CCl4 , dimethylnitrosamine (DMN) and bile duct ligation (BDL).

RESULTS

Luteolin inhibited proliferation, migration, collagen synthesis as well as expression of fibrosis-related genes in the activated HSCs and HSC-T6 cells stimulated with or without transforming growth factor-β1(TGFβ1) or platelet-derived growth factor (PDGF). Luteolin induced HSC apoptosis associated with the increased caspase 3 activity and p53 expression, and induced G1 arrest with the decreased expression of bcl-2, Cyclin E and p-Cdk-2. Moreover, luteolin significantly inhibited PDGF and TGFβ1-simulated phosphorylation of AKT and Smad pathway. In vivo study showed that luteolin administration markedly alleviated hepatic fibrosis along with reduced elevations of alanine aminotransferase and aspartate aminotransferase. HSCs were found to undergo apoptosis and decreased expression of p-Smad2 and p-AKT in luteolin-treated animals.

CONCLUSIONS

This study demonstrates that luteolin prevents the progression of liver fibrosis through multiple mechanisms and indicates that luteolin has potential for effective treatment of liver fibrosis.

Analysis of the intrahepatic ductular reaction and progenitor cell responses in hepatitis C virus recurrence after liver transplantation

Fibrosis in livers with hepatitis C virus (HCV) recurrence after liver transplantation (LT) can be rapidly progressive, and the mechanisms underlying this process are poorly understood. In livers with HCV infections in the non-LT setting, there is a significant relationship between the development of structures known as the ductular reaction (DR), hepatic progenitor cells (HPCs), and fibrosis. This study characterizes the DR, HPCs, and fibrosis associated with HCV recurrence after LT. Immunohistochemistry and confocal microscopy were used to characterize the DR, HPC, and fibrosis in liver biopsy specimens. Key findings were confirmed in a separate, independent cohort. The initial characterization cohort had 194 biopsy samples from 105 individuals with HCV recurrence after LT. The immunophenotype, morphology, and location of the DR were consistent with an HPC origin. The DR correlated with intrahepatic fibrosis (rs  = 0.529, P < 0.001) and the number of activated hepatic stellate cells (HSCs; rs  = 0.446, P < 0.001). There was an early occurrence of hepatocyte replicative arrest as well as increased hepatocyte proliferation that correlated with the DR (rs  = 0.295, P < 0.001). Replicative arrest preceded hepatocyte proliferation in early-stage injury. Hepatocyte proliferation decreased with advanced fibrosis; in contrast, the extent of the DR and the number of activated HSCs continued to increase. In the second cohort of 37 individuals, the DR and the number of HPCs similarly correlated with fibrosis and inflammation after LT. In conclusion, this is the first characterization of the DR in HCV-associated liver injury after LT. There was a significant correlation between the DR and the development of progressive fibrosis in HCV recurrence. These results suggest a pivotal role for both the DR and the HPC responses in the aggressive fibrosis seen with HCV recurrence after LT.

Endoplasmic reticulum stress is the crossroads of autophagy, inflammation, and apoptosis signaling pathways and participates in liver fibrosis

OBJECTIVE

The objective of the review is to examine the crossroads of autophagy, inflammation, and apoptosis signaling pathways and their participation in liver fibrosis.

INTRODUCTION

Endoplasmic reticulum (ER) stress was emerged as a common feature relevant to the pathogenesis of diseases associated with organ fibrosis. However, the functional consequences of these alterations on ER stress and the possible involvement in liver fibrosis were currently largely unexplored. Here, we will survey the recent literature in the field and discuss recent insights focusing on some cellular models expressing mutant proteins involved in liver fibrosis.

METHODS

A computer-based online search with PubMed, Scopus and Web of Science databases was performed for articles published, concerning ER stress, adaptation, inflammation and apoptosis with relevance to liver fibrosis.

RESULTS AND CONCLUSIONS

Progression of liver fibrosis requires sustained inflammation leading to hepatocytes apoptosis through ER stress, whereas associated with activation of hepatic stellate cells (HSCs) into a fibrogenic and proliferative cell type. Faced with persistent and massive ER stress, HSCs adaptation starts to fail and apoptosis occurs in reversal of liver fibrosis, possibly mediated through calcium perturbations, unfolded protein response, and the pro-apoptotic transcription factor CHOP. Although limited in scope, current studies underscored that ER stress is tightly linked to adaptation, inflammation and apoptosis, and recent evidences suggested that these processes are related to the pathogenesis of liver fibrosis and its recovery.

Endoplasmic reticulum stress-induced hepatic stellate cell apoptosis through calcium-mediated JNK/P38 MAPK and Calpain/Caspase-12 pathways

Recent reports considered that it was the disturbance of calcium homeostasis and the accumulation of misfolded proteins in the endoplasmic reticulum (ER) that activated hepatic stellate cells (HSCs) apoptosis and promoted fibrosis resolution. However, the signal-transducing events that are activated by ER stress after HSCs activation were incompletely understood. In this study, we induced ER stress with thapsigargin (TG), and determined the activation of calpain and the cleavage of caspase by analyzing the protein levels and the correspondingly increased intracellular calcium levels and the induction of the proapoptotic transcription factor CHOP. Moreover, the phosphorylation of JNK and p38 MAPK were followed by the activation of the executioner caspases, caspase-3. As expected, preventing an increase in intracellular calcium levels using intracellular calcium chelators, EGTA, and BAPTA/AM, could substantially inhibit the phosphorylation of JNK and p38 MAPK, abolish the activation of calpains, namely caspase-12, caspase-9, and caspase-3, and provide significant protection for TG-treated activated HSCs. Interestingly, pretreatment with p38 MAPK inhibitor SB202190, JNK inhibitor SP600125, the pan-caspase inhibitor z-VAD-FMK, or calpain inhibitors calpeptin, significantly reduced the cell apoptosis and the cleavage of caspase-12 and caspase-3. However, pretreatment with z-VAD-FMK failed to reduce the activation of calpain. Additionally, pretreatment with SB202190 and SP600125 also decreased the expression of CHOP. Importantly, PDGF-induced collagen Col1α1 and α-smooth muscle actin (α-SMA), markers for the perpetuation phase of HSCs activation, were inhibited in TG-treated activated HSCs. These findings showed that the Calpain/Caspase-12 activation induced by ER stress and the JNK/p38 MAPK phosphorylation induced by the increase of intracellular calcium concentration releasing from ER are the novel signaling pathway underlying the molecular mechanism of fibrosis recovery.

Caffeine prevents experimental liver fibrosis by blocking the expression of TGF-β

BACKGROUND

There is a growing body of evidence that caffeine exerts beneficial effects on the liver; however, the molecular mechanisms by which caffeine exerts beneficial effects on the liver are poorly defined.

AIMS

The aim of the present study was to examine the efficacy of caffeine in preventing thioacetamide (TAA)-induced cirrhosis in rats.

MATERIALS AND METHODS

Cirrhosis was induced by chronic TAA administration and the effects of coadministration of caffeine for 8 weeks were evaluated, including control groups.

RESULTS

The administration of TAA induced liver cirrhosis, which was inhibited by caffeine. Caffeine prevents elevation of liver enzymes. Liver histopathology and hydroxyproline levels were significantly lower in the rats treated with TAA plus caffeine compared with TAA only. Caffeine shows antioxidant properties by restoring the redox equilibrium [lipid peroxidation and glutathione peroxidase (GPx) levels]. Western blot assays showed blockade of the expression of transforming growth factor-β and its downstream inductor connective tissue growth factor. Similarly, caffeine decreases messenger RNA levels of these profibrogenic proteins. In addition, caffeine inhibits hepatic stellate cells because of blockade of the expression of α-smooth muscle actin; in the western blot assay, we also found low levels of mRNA of collagen α1. Zymography assays showed that caffeine had an effect on the activity of matrix metalloproteinases 2 and 9, but no effect on the expression of tissue inhibitor of metalloproteinases-1, using RT-PCR.

CONCLUSION

Our results show that caffeine prevents experimental cirrhosis; the mechanisms of action are associated with its antioxidant properties and mainly by its ability to block the elevation of the profibrogenic cytokine transforming growth factor-β, which may be associated with attenuation of the inflammatory and fibrotic processes.

Antifibrotic activity of galangin, a novel function evaluated in animal liver fibrosis model

This study aimed to investigate the effects of galangin on liver fibrosis in rats induced by subcutaneous injection of carbon tetrachloride (CCl4). The administration of CCl4 to rats for 12 weeks caused significant increase of hyaluronic acid, laminin, alanine transaminase, aspartate transaminase and decrease of total protein, albumin in serum, while the influences could be reversed by galangin. Galangin markedly reduced hepatic malondialdehyde, hydroxyproline concentration, increased activities of liver superoxide dismutase, glutathione peroxidase compared with CCl4-treated rats. Histological results indicated that galangin alleviated liver damage. In addition, treatment with galangin significantly down-regulated expressions of α-smooth muscle actin and transforming growth factor β1. These results suggest galangin can inhibit liver fibrosis induced by CCl4 in rats, which was probably associated with its effect on removing oxygen free radicals, decreasing lipid peroxidation, as well as inhibiting hepatic stellate cells activation and proliferation.

Biliary Proliferative Lesions in the Sprague-Dawley Rat

Whether biliary proliferative lesions in nonclinical species are predictive of potential hepatotoxicity in humans depends, at least in part, on the nature and severity of such changes in the nonclinical species. We reviewed published literature (clinical and nonclinical) and experimental data from rat toxicology studies conducted by GlaxoSmithKline and the National Institute of Environmental Health Sciences’ National Toxicology Program in an effort to better characterize the relative risk of hepatobiliary effects in humans. Available evidence supports the interpretation that minimal “typical” appearing bile duct hyperplasia limited to the portal triads may be considered non-adverse in the rat and is of little to no concern to humans. The toxicological relevance of mild to moderate “typical” hyperplasia is less certain, and may be considered adverse in the rat and potentially pose a risk for humans, particularly if accompanied by evidence of hepatobiliary injury or functional compromise. In addition, any proliferative lesion that includes atypical or dysplastic epithelial changes, oval cell proliferation, and/or significant extension beyond the portal tracts is considered more ominous and may be considered adverse in the rat.

Semaphorin 7A contributes to TGF-β-mediated liver fibrogenesis

Semaphorin7A (SEMA7A) is a membrane-anchored protein involved in immune and inflammatory responses, exerting an effect on pulmonary fibrosis. Thus, we aimed to investigate the role of SEMA7A in hepatic fibrosis. Liver injury was induced in vivo by carbon tetrachloride i.p. injection or bile duct ligation in wild-type and SEMA7A knockout (KO) mice. Human and mouse liver samples and primary mouse hepatic cell populations were used for Western blot analysis, quantitative real-time RT-PCR, and immunohistochemistry. SEMA7A is highly expressed in hepatic stellate cells (HSCs). The expression of SEMA7A and its receptor β1-integrin subunit increase during liver injury and in activated HSCs. Transforming growth factor β-stimulated HSCs showed increased expression of SEMA7A in a SMAD2/3-independent manner, leading to increased expression of fibrogenic and inflammation markers. This pattern was significantly blunted in SEMA7A KO HSCs. Overexpression of SEMA7A in HSCs showed increased fibrogenic and inflammation markers expression. In vivo, SEMA7A KO mice treated with carbon tetrachloride and bile duct ligation developed reduced fibrosis versus wild-type mice. Moreover, SEMA7A expression increased in liver samples of patients with fibrosis versus healthy controls. SEMA7A was expressed in the liver and was increased in the course of liver fibrosis, both in mice and in humans. SEMA7A was mainly expressed in HSCs with respect to other cell types in the liver and plays a critical role in regulating fibrosis.

An efficient method for decellularization of the rat liver

BACKGROUND/PURPOSE

Using gradient ionic detergent, we optimized the preparation procedure for the decellularized liver biologic scaffold, and analyzed its immunogenicity and biocompatibility.

METHODS

EDTA, hypotonic alkaline solution, Triton X-100, and gradient sodium dodecyl sulfate (1%, 0.5%, and 0.1%, respectively) were prepared for continuous perfusion through the hepatic vascular system. The decellularization of the liver tissue was performed with the optimized reagent buffer and washing protocol. In addition, the preservation of the original extracellular matrix was observed. To analyze its biocompatibility, the scaffold was embedded in a heterologous animal and the inflammation features, including the surrounding cell infiltration and changes of the scaffold architecture, were detected. The cell-attachment ability was also validated by the perfusion culture of HepG2 cells with the scaffold.

RESULTS

By using gradient ionic detergent, we completed the decellularization process in approximately 5 h, which was shorter than >10 hours in previous experiments (p<0.001). The extracellular matrix was kept relatively intact, with no obvious inflammatory cellular infiltration or structural damage in the grafted tissue. The engraftment efficiencies of HepG2 were 86±5% (n=8). The levels of albumin and urea synthesis were significantly superior to the ones in traditional two-dimensional culture.

CONCLUSION

The current new method can be used efficiently for the decellularization of the liver biologic scaffold with satisfying biocomparability for application both in vivo and in vitro.

Mechanism of autoimmune hepatic fibrogenesis induced by an adenovirus encoding the human liver autoantigen cytochrome P450 2D6

Autoimmune hepatitis type 2 (AIH-2) is a severe autoimmune liver disease with unknown etiology. We recently developed the CYP2D6 mouse model for AIH-2, in which mice are challenged with an adenovirus (Ad-2D6) expressing human cytochrome P450 2D6 (hCYP2D6), the major autoantigen in AIH-2. Such mice develop chronic hepatitis with cellular infiltrations and generation of hCYP2D6-specific antibodies and T cells. Importantly, the CYP2D6 model represents the only model displaying chronic fibrosis allowing for a detailed investigation of the mechanisms of chronic autoimmune-mediated liver fibrogenesis. We found that hCYP2D6-dependent chronic activation of hepatic stellate cells (HSC) resulted in an increased extracellular matrix deposition and elevated expression of α-smooth muscle actin predominantly in and underneath the liver capsule. The route of Ad-2D6 infection dramatically influenced the activation and trafficking of inflammatory monocytes, NK cells and hCYP2D6-specific T cells. Intraperitoneal Ad-2D6 infection caused subcapsular fibrosis and persistent clustering of inflammatory monocytes. In contrast, intravenous infection caused an accumulation of hCYP2D6-specific CD4 T cells throughout the liver parenchyma and induced a strong NK cell response preventing chronic HSC activation and fibrosis. In summary, we found that the location of the initial site of inflammation and autoantigen expression caused a differential cellular trafficking and activation and thereby determined the outcome of AIH-2-like hepatic damage and fibrosis.