Review of experimental models for inducing hepatic cirrhosis by bile duct ligation and carbon tetrachloride injection

Fucoidan alleviates the hepatorenal syndrome through inhibition organic solute transporter α/β to reduce bile acids reabsorption

The high levels of bile acids are a critical factor in hepatorenal syndrome. Organic solute transporter α/β (Ostα/β) participate in bile acids reabsorption in the kidney. Fucoidan has the great potential in protecting against liver and kidney injury. However, whether Ostα/β increase bile acids reabsorption in bile duct ligature (BDL)-induced hepatorenal syndrome and the blockade of fucoidan are still not clear. Male mice that received BDL were given to fucoidan (at 12.5, 25 and 50 ​mg/kg) through intraperitoneal injection once daily for three weeks. The serum, liver and kidney samples of these experimental mice were collected to carry out biochemical, pathological and Western blot analysis. In this study, fucoidan significantly lowered serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), decreased serum levels of uric acid, creatinine and uric nitrogen, restored the deregulation of the renal urate transporter 1 (URAT1), organic anion transporter 1 (OAT1), and organic cation/carnitine transporter 1/2 (OCTN1/2), consistence with alleviation BDL-induced liver and kidney dysfunction, inflammation and fibrosis in mice. Furthermore, fucoidan significantly hampered Ostα/β and reduced bile acids reabsorption in BDL-induced mice, protected against AML12 and HK-2 ​cells injury in vitro. These results demonstrate that fucoidan alleviates BDL-induced hepatorenal syndrome through inhibition Ostα/β to reduce bile acids reabsorption in mice. Therefore, suppression of Ostα/β by fucoidan may be a novel strategy for attenuating hepatorenal syndrome.

Preventive effect of isostrictiniin from Nymphaea candida on carbon tetrachloride-induced hepatic fibrosis in mice

This study aimed to investigate the preventive effect of isostrictiniin (ISO) from Nymphaea candida against CCl₄-induced hepatic fibrosis (HF) in mice. HF in mice was induced by intraperitoneally injecting 10% CCl₄ olive oil solution twice a week. After intragastric administration for 8 weeks. ISO (25, 50, or 100 mg/kg) could significantly reduce the serum AST, ALT, ALP, HA, LN, PC-III, C-IV, IL-1β, and TNF-α levels in HF mice, and the collagen fiber deposition in ISO group was significantly less than that in the model group. Compared with control group, the protein expression of IKKα, NF-ҡB p65, p-NF-ҡKB p65, p-IҡBα in model group were increased as well as the relative content of IKKα, NF-ҡB p65, and IҡBα mRNA. ISO could reverse the expression of these relative proteins and mRNA in HF mice. Our findings confirm that ISO has anti-HF activity, and its mechanism is related to the regulation of NF-ҡB pathway.

An update on animal models of liver fibrosis

The development of liver fibrosis primarily determines quality of life as well as prognosis. Animal models are often used to model and understand the underlying mechanisms of human disease. Although organoids can be used to simulate organ development and disease, the technology still faces significant challenges. Therefore animal models are still irreplaceable at this stage. Currently, in vivo models of liver fibrosis can be classified into five categories based on etiology: chemical, dietary, surgical, transgenic, and immune. There is a wide variety of animal models of liver fibrosis with varying efficacy, which have different implications for proper understanding of the disease and effective screening of therapeutic agents. There is no high-quality literature recommending the most appropriate animal models. In this paper, we will describe the progress of commonly used animal models of liver fibrosis in terms of their development mechanisms, applications, advantages and disadvantages, and recommend appropriate animal models for different research purposes.

Selective biliary occlusion in rodents: description of a new technique

Background

Modern therapy concepts are of limited success in patients with cholestasis (e.g., biliary occluding malignancies). Therefore, we established a new animal model enabling simultaneous investigation of liver regeneration and hepato-biliary remodelling in biliary obstructed and biliary non-obstructed liver lobes.

Methods

Biliary occlusion of different extent was induced in 50 male rats: Ligation and transection of the common bile duct (100% of liver, tBDT, n=25); or of the left bile duct (70% of liver, sBDT, n=25). At postoperative days 1, 3, 7, 14 and 28 we assessed the hepatic histomorphological alterations, proliferative repair, progress of liver fibrosis (HE, BrdU, EvG) and signs of liver regeneration (liver lobe weight gain). In addition, we determined systemic markers of hepatocellular injury (ASAT, ALAT), cholestasis (Bilirubin) and synthetic liver function (INR). The animals were monitored daily (body weight gain, stress score, survival).

Results

All animals survived until the planned date of sacrifice. sBDT induced in the biliary occluded liver lobes similar histomorphological alterations, proliferative repair and progress of liver fibrosis like tBDT. In the biliary non-ligated liver lobes in sBDT animals we noticed a temporarily enhanced biliary proliferation and a persistent low grade liver fibrosis in the periportal area.

Conclusions

Our model of sBDT represents a safe and valid method to induce selective cholestasis. The model enables further comparative investigation of liver regeneration in different extents of occlusive cholestasis (e.g., mimicking biliary occluding malignancies).

The Interplay Between Biliary Occlusion and Liver Regeneration: Repeated Regeneration Stimuli Restore Biliary Drainage by Promoting Hepatobiliary Remodeling in a Rat Model

Background and Aims

Patients with malignant biliary obstruction do not seem to benefit from “two-stage hepatectomy” due to an impairment of liver regeneration. We designed a novel model of “repeated regeneration stimuli” in rats mimicking a “two-stage hepatectomy” with selective or complete biliary occlusion mimicking Klatskin tumors III° or IV°. Using this new model, we wanted to investigate (1) the impact of preexistent cholestasis of different extent on the time course of liver regeneration and (2) the dynamics of hepatobiliary remodeling under regeneration conditions.

Materials and Methods

Rats were subjected to a sequence of three operations: surgical induction of biliary occlusion, followed by “repeated regeneration stimuli” consisting of ligation of the left branch of the portal vein (supplying 70% of the liver volume, sPVL) as first stage and a 70%-hepatectomy (70%PHx) as second stage. Biliary occlusion (1st procedure) was induced by ligating and transection of either the common (100%, tBDT) or the left bile duct (70%, sBDT). A sham operation without ligating the bile duct was performed as control (0%, Sham). Two weeks later, on day 14 (POD14), the sPVL (2nd procedure) was performed. Another week later (POD 21), the 70%PHx (3rd procedure) took place and animals were observed for 1 week (POD 28). The first experiment (n = 45 rats) was dedicated to investigating liver regeneration (hypertrophy/atrophy), proliferative activity and hepatobiliary histomorphology (2D-histology: HE, BrdU) in the future liver remnant (FLR). The second experiment (n = 25 rats) was performed to study the dynamics of hepatobiliary remodeling in livers with different regenerative pressure (tBDT only POD21 vs. tBDT only POD 28 vs. tBDT + sPVL vs. tBDT + 70%PHx vs. tBDT + sPVL + 70%PHx) using μCT scans of explanted livers.

Results

Effect of biliary occlusion

Total biliary occlusion (tBDT) led to a 2.4-fold increase in whole liver volume due to severe biliary proliferation within 14 days. In contrast, partial biliary occlusion (sBDT) caused only a volume gain of the obstructed liver lobes due to biliary proliferates, resulting in a minor increase of total liver volume (1.7-fold) without an increase in bilirubin levels.

Liver regeneration and atrophy

As expected, sPVL caused substantial volume gain (tBDT: 3-fold; sBDT: 2.8-fold; Sham 2.8-fold) of FLR and a substantial volume loss (tBDT: 0.9-fold; sBDT: 0.6-fold; Sham: 0.4-fold) of the portally deprived “future resected lobes” compared to the preoperative liver volume. The subsequent 70%PHx promoted a further volume gain of the FLR in all groups (tBDT: 4-fold; sBDT: 3-fold; Sham 3-fold compared to original volume) until POD 28. Hepatobiliary remodeling: After tBDT, we identified histologically three phases of hepatobiliary remodeling in the FLR. Following tBDT, biliary proliferates developed, replacing about 15% of the hepatocellular tissue. After sPVL we found incomplete restoration of the hepatocellular tissue with a visible reduction of the biliary proliferates. The 70%PHx led to an almost complete recovery of the hepatocellular tissue in the FLR with a nearly normal liver architecture. In contrast, after sBDT and Sham we observed a near normal liver morphology in the FLR at all time points. CT-scanning of the explanted livers and subsequent 3D reconstruction visualized the development of extrahepatic biliary collaterals. Collaterals were detected in 0/5 cases 1 week after sPVL (first regeneration stimulus), and in even more cases (3/5) 1 week after the 70%PHx (second regeneration stimulus). Histological workup identified the typical biliary cuboid epithelium as inner lining of the collaterals and peribiliary glands.

Conclusion

Liver volume of the FLR increased in cholestatic rats mainly due to biliary proliferates. Application of repeated regeneration stimuli in the style of a “two-stage hepatectomy” promoted almost full restoration of hepatocellular tissue and architecture in the FLR by reestablishing biliary drainage via formation of biliary collaterals. Further exploration of the dynamics in hepatobiliary modeling using this model might help to better understand the underlying mechanism.

Lingonberry Anthocyanins Inhibit Hepatic Stellate Cell Activation and Liver Fibrosis via TGFβ/Smad/ERK Signaling Pathway

Phytochemicals from lingonberry have rich pharmacological value and may play an essential role in treating liver diseases. We investigated the regulatory role of lingonberry anthocyanins (LA) on HSC activation in vitro and liver fibrogenesis in vivo. The viability of HSCs treated with LA was significantly reduced in a dose-dependent manner at the concentration of 25-100 μg/mL, in which the monomers of LA also reduced the proliferation of HSCs via IC50 assay. The inducer transforming growth factor β1 (TGFβ1) and the effector α-smooth muscle actin (α-SMA) of HSC activation were all decreased both in protein and RNA levels treated by LA. Moreover, LA alleviated CCl₄-induced liver fibrosis in rats, reducing collagen aggregation and production and decreasing the hydroxyproline (HYP) and malondialdehyde (MDA) levels in the liver tissue. Moreover, LA reduced the indexes of serum liver fibrosis and reversed the index of serum liver function in CCl₄-induced rats. Furthermore, the antioxidant enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT), in the liver tissue and serum were significantly increased upon treatment with LA. Importantly, LA promoted hepatic parenchymal cell proliferation and inhibited the expression of TGFβ/Smad/extracellular regulated protein kinase (ERK) signaling pathway-related genes. This study demonstrates the anti-liver fibrosis activity of LA and investigates its mechanism, which may provide a novel strategy for treating liver fibrosis using lingonberry.

Influence of Liver Cirrhosis on Blood Glucose, Insulin Sensitivity and Islet Function in Mice

BACKGROUND

The relationship between cirrhosis and diabetes is controversial. We studied the influence of cirrhosis on glucose levels and islet function and explored its possible mechanisms.

MATERIALS AND METHODS

Cirrhosis was induced in male C57BL/6 mice by bile duct ligation (BDL). Serum biochemical parameters were determined, and oral glucose tolerance tests (OGTT) were performed at 4 and 8 weeks after BDL. Histopathology and phospho-NF-κB-p65/I-kappa B α immunohistochemical staining of the liver and islet were observed. The protein levels of the insulin signaling system and the gene expression of insulin-degrading enzyme (IDE) in the liver and muscle were determined. The activity of glucokinase (GCK) and glucose 6-phosphatase (G6P) and glycogen levels in liver homogenates were measured.

RESULTS

After BDL, the mice developed cirrhosis, and fasting glucose decreased significantly, but 2 h postprandial glucose increased, and the insulin areas under the curves increased. At 4 weeks of BDL, the ratios of phospho-NF-κB-p65/I-kappa B α accumulation in the liver and islet increased, the activity of G6P and the glycogen content in liver homogenates decreased, the insulin signaling system and the gene expression of IDE in the liver was downregulated, and the islet areas were decreased. After 8 weeks, these changes were more severe.

CONCLUSIONS

In different periods of cirrhosis, the levels of fasting glucose and 2 h postprandial glucose changed in different amplitudes. Glycogen concentrations and the activity of G6P in the liver were decreased. The mice developed insulin resistance and the islet areas were decreased. The NF-κB pathway may play a role in the process.

Hepatoprotective effect of ethanolic extract of sugarcane (Saccharum officinarum Linn.) leaves

OBJECTIVES

The sugarcane leaf is rich inphytochemical content. It is rarely used because it is a waste although it has potential activity as antimutation, anti inflammation, and antioxidation. There is no study about its hepatoprotective activity yet. This study was conducted to determine the hepatoprotection of sugarcane leaves in tested animals with liver acute injury induced by carbon tetrachloride (CCl₄).

METHODS

Twenty-four Wistar strain rats were divided into three groups of experimental animals (dose 300, 400, and 500 mg/kg) and three control groups (normal, positive, and negative). The ethanol extract of sugarcane leaves obtained from Panti, Jember, was made using the maceration method. The animals were treated for 14 days by giving the extract to the treatment group. One hour after treatment on the last day, the test animals were given CCl₄ intraperitoneally except for the normal group. On the 15th day, the blood of the test animal was taken to be tested for the biochemical value of the liver (aspartate transaminase (AST), alanine aminotransferase (ALT), alanine phosphatase (ALP), and bilirubin) and examined for its liver to be made histological preparations.

RESULTS

The results showed that the treatment with a dose of 500 mg/kg was able to decrease AST, ALT, ALP, and bilirubin parameters compared to the negative control. The extract also provided improvements in liver tissue histology compared to the negative control.

CONCLUSIONS

Sugarcane leaf ethanol extract (SCLE) has a potential hepatoprotective effect.

Liver inflammation at the time of spinal cord injury enhances intraspinal pathology, liver injury, metabolic syndrome and locomotor deficits

The current high obesity rates mean that neurological injuries are increasingly sustained on a background of systemic pathology, including liver inflammation, which likely has a negative impact on outcomes. Because obesity involves complex pathology, the effect of hepatic inflammation alone on neurological recovery is unknown. Thus, here we used a gain-of-function model to test if liver inflammation worsens outcome from spinal cord injury (SCI) in rats. Results show liver inflammation concomitant with SCI exacerbated intraspinal pathology and impaired locomotor recovery. Hepatic inflammation also potentiated SCI-induced non-alcoholic steatohepatitis (NASH), endotoxemia and insulin resistance. Circulating and cerebrospinal levels of the liver-derived protein Fetuin-A were higher in SCI rats with liver inflammation, and, when microinjected into intact spinal cords, Fetuin-A caused macrophage activation and neuron loss. Thus, liver inflammation functions as a disease modifying factor to impair recovery from SCI, and Fetuin-A is a potential neuropathological mediator. Since SCI alone induces acute liver inflammation, the liver may be a novel clinical target for improving recovery from SCI.

Liver fibrosis-induced muscle atrophy is mediated by elevated levels of circulating TNFα

Liver cirrhosis is a critical health problem associated with several complications, including skeletal muscle atrophy, which adversely affects the clinical outcome of patients independent of their liver functions. However, the precise mechanism underlying liver cirrhosis-induced muscle atrophy has not been elucidated. Here we show that serum factor induced by liver fibrosis leads to skeletal muscle atrophy. Using bile duct ligation (BDL) model of liver injury, we induced liver fibrosis in mice and observed subsequent muscle atrophy and weakness. We developed culture system of human primary myotubes that enables an evaluation of the effects of soluble factors on muscle atrophy and found that serum from BDL mice contains atrophy-inducing factors. This atrophy-inducing effect of BDL mouse serum was mitigated upon inhibition of TNFα signalling but not inhibition of myostatin/activin signalling. The BDL mice exhibited significantly up-regulated serum levels of TNFα when compared with the control mice. Furthermore, the mRNA expression levels of Tnf were markedly up-regulated in the fibrotic liver but not in the skeletal muscles of BDL mice. The gene expression analysis of isolated nuclei revealed that Tnf is exclusively expressed in the non-fibrogenic diploid cell population of the fibrotic liver. These findings reveal the mechanism through which circulating TNFα produced in the damaged liver mediates skeletal muscle atrophy. Additionally, this study demonstrated the importance of inter-organ communication that underlies the pathogenesis of liver cirrhosis.

Novel imaging-based approaches for predicting the hepatic venous pressure gradient in a porcine model of liver cirrhosis and portal hypertension

AIMS

Hepatic venous pressure gradient (HVPG) is critical for staging and prognosis prediction of portal hypertension (PH). However, HVPG measurement has limitations (e.g., invasiveness). This study examined the value of non-invasive, imaging-based approaches including magnetic resonance elastography (MRE) and intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) for the prediction of HVPG in a porcine model of liver cirrhosis and PH.

MAIN METHODS

Male Bama miniature pigs were used to establish a porcine model of liver cirrhosis and PH induced by embolization. They were randomly assigned to an experimental group (n = 12) and control group (n = 3). HVPG was examined before and after transjugular intrahepatic portosystemic shunt (TIPS). MRE and IVIM-DWI were performed to obtain quantitative parameters including liver stiffness (LS) in MRE, tissue diffusivity (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) in IVIM-DWI. The correlation between HVPG and the parameters was assessed.

KEY FINDINGS

LS values were significantly greater in the experimental group, while f values were significantly decreased at 4, 8, and 12 weeks after embolization compared to the control group. Furthermore, HVPG was significantly lower immediately after versus before TIPS. In parallel, LS and f values showed significant alterations after TIPS, and these changes were consistent with a reduction in HVPG. Spearman analysis revealed a significant correlation between the parameters (LS and f) and HVPG. The equation was eventually generated for prediction of HVPG.

SIGNIFICANCE

The findings show a good correlation between HVPG and the quantitative parameters; thus, imaging-based techniques have potential as non-invasive methods for predicting HVPG.

Regenerative effect of mesenteric fat stem cells on ccl4-induced liver cirrhosis, an experimental study

Background

Liver cirrhosis is a chronic disease in which normal liver tissue is replaced by fibrous tissue, leads to liver malfunction. Although transplantation is the most certain cure, stem cell therapies are shedding light on efforts to regenerate cirrhotic liver. The purpose of this study was to evaluate the regenerative potential of mesenteric fat stem cells in CCL4-induced liver cirrhosis in an animal model.

Methods

Thirty rats were treated with the mixture of CCL4 and olive oil intraperitoneally by a dose of 0.2 ml (0.1 ml CCL4 and 0.1 ml olive oil) every other day for 16 weeks till cirrhosis signs appeared. Fifteen rats were randomly selected as control group. Others treated by mesenteric fat derived mesenchymal stem cells transferred into the liver parenchyma.

Results

After 5 weeks, rats received stem cells had improved clinically by increased movements, appetite, improvement in overall behavior and decreased abdomen size. Histopathologically, liver cells showed state of regeneration and forming new colonies.

Conclusion

Liver cirrhosis was induced. The mesenchymal stem cells derived from mesenteric adipose tissue could improve hepatic status of the rats, as cirrhotic livers were regenerated back into normal appearing parenchyma. Rats' clinical behavior also reached healthy status.

Carbon tetrachloride (CCl4) accelerated development of non-alcoholic fatty liver disease (NAFLD)/steatohepatitis (NASH) in MS-NASH mice fed western diet supplemented with fructose (WDF)

BACKGROUND

Multiple murine models of nonalcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) have been established by using obesogenic diets and/or chemical induction. MS-NASH mouse (formally FATZO) is a spontaneously developed dysmetabolic strain that can progress from hepatosteatosis to moderate fibrosis when fed a western diet supplemented with 5% fructose (WDF). This study aimed to use carbon tetrachloride (CCl4) to accelerate and aggravate progression of NAFLD/NASH in MS-NASH mouse.

METHODS

Male MS-NASH mice at 8 weeks of age were fed WDF for the entire study. Starting at 16 weeks of age, CCl4 was intraperitoneally administered twice weekly at a dose of 0.2 mL/kg for 3 weeks or 0.08 mL/kg for 8 weeks. Obeticholic acid (OCA, 30 mg/kg, QD) was administered in both MS-NASH and C57Bl/6 mice fed WDF and treated with CCl4 (0.08 mL/kg).

RESULTS

WDF enhanced obesity and hepatosteatosis, as well as induced moderate fibrosis in MS-NASH mice similar to previous reports. Administration of CCl4 accelerated liver fibrosis with increased bridging and liver hydroxyproline contents, but had no significant impact on liver steatosis and lipid contents. High dose CCl4 caused high mortality and dramatic elevation of ALT and ASL, while low dose CCl4 resulted in a moderate elevation of ALT and AST with low mortality. Compared to C57BI/6 mice with WDF and CCl4 (0.08 mL/kg), MS-NASH mice had more prominent hepatosteatosis and fibrosis. OCA treatment significantly lowered liver triglycerides, steatosis and fibrosis in both MS-NASH and C57Bl/6 mice fed WDF with CCl4 treatment.

CONCLUSIONS

CCl4 reduced induction time and exacerbated liver fibrosis in MS-NASH mice on WDF, proving a superior NASH model with more prominent liver pathology, which has been used favorably in pharmaceutical industry for testing novel NASH therapeutics.

Roseotoxin B alleviates cholestatic liver fibrosis through inhibiting PDGF-B/PDGFR-β pathway in hepatic stellate cells

Identifying effective anti-fibrotic therapies is a major clinical need that remains unmet. In the present study, roseotoxin B was shown to possess an improving effect on cholestatic liver fibrosis in bile duct–ligated mice, as proved by histochemical and immunohistochemical staining, hepatic biochemical parameters, and TUNEL apoptotic cell detection in tissue sections. Using cellular thermal shift assay, computational molecular docking, microscale thermophoresis technology, and surface plasmon resonance biosensor, we confirmed that PDGFR-β was a direct target of roseotoxin B in fibrotic livers. Of note, human tissue microarrays detected pathologically high expression of p-PDGFR-β in liver samples of ~80% of patients with liver fibrosis and cirrhosis. PDGF-B/PDGFR-β pathway promotes transdifferentiation and excessive proliferation of hepatic stellate cells (HSCs), which is a very crucial driver for liver fibrosis. Meaningfully, roseotoxin B blocked the formation of PDGF-BB/PDGFR-ββ complex by targeting the D2 domain of PDGFR-β, thereby inhibiting the PDGF-B/PDGFR-β pathway in HSCs. In summary, our study provided roseotoxin B as a unique candidate agent for the treatment of liver fibrosis.

Dysregulation of UDP-glucuronosyltransferases in CCl4 induced liver injury rats

UDP-glucuronosyltransferases (UGTs) are a family of phase II drug metabolizing enzymes that catalyze glucuronidation of numerous endogenous and exogenous substrates. Carbon tetrachloride (CCl₄) is widely used to develop liver injuries mimicking human liver diseases. However, effects of CCl₄ on the expression and activities of UGTs and the mechanism have not been fully elucidated. The present study aims to elucidate the dysregulation patterns of major UGTs induced by CCl₄. Biochemical and histopathological results showed that CCl₄ exerted hepatotoxicity in rats. The mRNA levels of UGTs were all significantly reduced in acute liver injury rats. However, mRNA levels of UGT1A1, 1A6, 2B1 and 2B2 were up-regulated while the UGT2B3, 2B6 and 2B12 levels were reduced in chronic CCl₄-induced liver fibrosis rats. The protein expression of UGT1A1, 1A6 and 2B were decreased in acute liver injury rats. UGT1A1 and 1A6 proteins were increased, whereas UGT2B protein was reduced in liver fibrosis rats. In addition, CCl₄ inhibited the enzyme activities of UGTs in rats. Moreover, the dysregulation of UGTs was accompanied by the decreased mRNA expression of Nrf2, CAR, FXR, PXR, PPAR-α and their corresponding target genes, except for Nrf2, HO-1, AhR and CYP1A1 in liver fibrosis rats. These findings suggest that dysregulation of UGTs under CCl₄ exposure is isoform-specific, which could have a complex impact on drug efficacy and endogenous metabolism. Different exposure durations of CCl₄ (single vs multiple doses) could have differential effects on rat hepatic UGTs expression.

MicroRNAs in Animal Models of HCC

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality. Molecular heterogeneity and absence of biomarkers for patient allocation to the best therapeutic option contribute to poor prognosis of advanced stages. Aberrant microRNA (miRNA) expression is associated with HCC development and progression and influences drug resistance. Therefore, miRNAs have been assayed as putative biomarkers and therapeutic targets. miRNA-based therapeutic approaches demonstrated safety profiles and antitumor efficacy in HCC animal models; nevertheless, caution should be used when transferring preclinical findings to the clinics, due to possible molecular inconsistency between animal models and the heterogeneous pattern of the human disease. In this context, models with defined genetic and molecular backgrounds might help to identify novel therapeutic options for specific HCC subgroups. In this review, we describe rodent models of HCC, emphasizing their representativeness with the human pathology and their usefulness as preclinical tools for assessing miRNA-based therapeutic strategies.

Impairment of natriuresis and diuresis induced by intrarenal adrenoceptor mechanisms in an experimental model of cirrhosis in rats

The contribution of intrarenal alpha-2 adrenergic receptors in mediating the enhanced renal excretory responses evoked by the alpha-2-agonist xylazine was examined in a model of cirrhosis in rats. In sham-operated rats, xylazine (0.2 mg/kg, i.v.) increased diuresis and natriuresis (urine flow, control: 78 ± 12.1, 10 min: 155 ± 17, 20 min: 194 ± 19, 30 min: 146 ± 16, 40 min: 114 ± 13, 50 min: 95 ± 10.5 μl/min/g; urinary sodium excretion, control: 6.75 ± 2.08, 10 min: 7.12 ± 2.1, 20 min: 13.4 ± 4.6, 30 min: 14.6 ± 4.02, 40 min: 12.05 ± 2.35, 50 min: 12.7 ± 2.45 μeq/min/g), which was accompanied by a significant reduction in renal sympathetic nerve activity (RSNA) (control: 100, 10 min: 39.5 ± 5.8, 20 min: 53 ± 8.8, 30 min: 72 ± 7.0, 40 min: 83 ± 5.0, 50 min: 94 ± 6.1 AU). Xylazine (0.2 mg/kg) in cirrhotic animals, despite resulting in a significant reduction in RSNA (control: 100, 10 min: 73 ± 4.3*, 20 min: 70 ± 5.0*, 30 min: 76 ± 7.0*, 40 min: 85 ± 5.5*, 50 min: 92 ± 4.8* AU), was unable to increase natriuresis. A higher dose (20 mg/kg) of xylazine was not capable of increasing natriuresis and diuresis, even in the presence of a robust reduction in RSNA. Renal denervation did not alter the onset and time course of cirrhosis. The results indicated that during the development of cirrhosis, there is an adaptive process that disables the intrarenal alpha-2 adrenoceptor mechanisms that selectively promote water and urinary sodium excretion via a sympathetic renal nerve-independent mechanism. Thus, in cirrhotic rats, the diuresis/natriuresis induced by xylazine is independent on RSNA. Intrarenal and/or hormonal changes are probably involved in the impairment of xylazine-induced diuresis/natriuresis in cirrhosis.

Rat multicellular 3D liver microtissues to explore TGF-β1 induced effects

Chronic liver damage can lead to fibrosis, encompassing hepatocellular injury, activation of Kupffer cells (KC), and activation of hepatic stellate cells (HSC). Inflammation and TGF-β1 are known mediators in the liver fibrosis adverse outcome pathway (AOP). The aim of this project was to develop a suitable rodent cell culture model for the investigation of key events involved in the development of liver fibrosis, specifically the responses to pathophysiological stimuli such as TGF-β1 and LPS-triggered inflammation. We optimized a single step protocol to purify rat primary hepatocytes (Hep), HSC and KC cells to generate 3D co-cultures based on the hanging drop method. This primary multicellular model responded to the profibrotic cytokine TGF-β1 (1 ng/mL) with signs of hepatocellular damage, inflammation and ultimately HSC activation (increase in αSMA expression). LPS elicited an inflammatory response characterized by increased expression of cytokines. 3D-monocultures comprising only Hep displayed different responses, underlying that parenchymal and non-parenchymal cells need to be present in the system to recapitulate fibrosis. The data also suggest that pre-activated HSC may reverse to a quiescent phenotype in 3D, probably due to the more physiological conditions.

A new rhodium(I) NHC complex inhibits TrxR: In vitro cytotoxicity and in vivo hepatocellular carcinoma suppression

Thioredoxin reductase (TrxR) is often overexpressed in different types of cancer cells including hepatocellular carcinoma (HCC) cells and regarded as a target with great promise for anticancer drug research and development. Here, we have synthesized and characterized nine new designed rhodium(I) N-heterocyclic carbene (NHC) complexes. All of them were effective towards cancer cells, especially complex 1e was more active than cisplatin and manifested strong antiproliferative activity against HCC cells. In vivo anticancer studies showed that 1e significantly repressed tumor growth in an HCC nude mouse model and ameliorated liver lesions in a chronic HCC model caused by CCl₄. Notably, a mechanistic study revealed that 1e can strongly inhibit TrxR system both in vitro and in vivo. Furthermore, 1e promoted intracellular ROS accumulation, damaged mitochondrial membrane potential, promoted cancer cell apoptosis and blocked the cells in the G1 phase.

Common Bile Duct Ligation as Model for Secondary Biliary Cirrhosis

Cholestatic liver disease covers a range of biliary disorders marked by an impaired bile duct flow. Various conditions can result in bile obstruction including choledocholithiasis, surgical trauma, and autoimmune disorders. Cholestatic liver disease can be mild but generally progresses to more severe conditions with increased hepatobiliary injury, cholangitis, and ultimately liver fibrosis and cirrhosis. An extensively used experimental model to investigate the pathophysiology of biliary cirrhosis and potential novel therapies is the common bile duct ligation in mice and rats. Common bile duct ligation induces the different stages of cholestatic-induced liver disease being cholestasis, subsequently accompanied by inflammation and finally liver fibrosis and cirrhosis. In this protocol, an outline of the surgical procedures to conduct common bile duct ligation in mice is provided. The major steps include the isolation of the common bile duct, followed by ligation and dissection.

Assessment of animal experimental models of toxic liver injury in the context of their potential application as preclinical models for cell therapy

Preclinical animal models allow to study development and progression of several diseases, including liver disorders. These studies, for ethical reasons and medical limits, are impossible to carry out in human patients. At the same time, such experimental models constitute an important source of knowledge on pathomechanisms for drug- and virus-induced hepatotoxicity, both acute and chronic. Carbon tetrachloride, D-Galactosamine, and retrorsine are xenobiotics that can be used in immunocompetent animal models of hepatotoxicity, where chemical-intoxicated livers present histological features representative of human viruses-related infection. A prolonged derangement into liver architecture and functions commonly lead to cirrhosis, eventually resulting in hepatocellular carcinoma. In human, orthotopic liver transplantation commonly resolve most the problems related to cirrhosis. However, the shortage of donors does not allow all the patients in the waiting list to receive an organ on time. A promising alternative treatment for acute and chronic liver disease has been advised in liver cell transplantation, but the limited availability of hepatocytes for clinical approaches, in addition to the immunosuppressant regiment required to sustain cellular long-term engraftment have been encouraging the use of alternative cell sources. A recent effective source of stem cells have been recently identified in the human amnion membrane. Human amnion epithelial cells (hAEC) have been preclinically tested and proven sufficient to rescue immunocompetent rodents lethally intoxicated with drugs. The adoption of therapeutic procedures based on hAEC transplant in immunocompetent recipients affected by liver diseases, as well as patients with immune-related disorders, may constitute a successful new alternative therapy in regenerative medicine.

Development and validation of a primate model for liver fibrosis

INTRODUCTION

Many liver diseases involve liver fibrosis. Most preclinical studies of liver fibrosis are carried out in small animals such as rodents, and thus lack direct potential for extrapolation to human diseases. The aim of the current study was to develop a primate model for liver fibrosis with greater relevance to translational research.

METHODS

Liver fibrosis was induced in adult male healthy rhesus monkeys using repeated CCl₄ treatment (40% in olive oil, 1.5 ml/kg once every 3 days via peritoneal injection, subcutaneous injection or gastric gavage). Liver biopsy was conducted at various time points for histologic examination. Blood samples were taken for standard liver function test.

RESULTS

Gastric gavage was the optimal approach for establishing stably liver fibrosis without animal loss due to toxicity. The progression of fibrosis appeared to involve epithelial to mesenchymal transition and hepatic ductular reaction.

CONCLUSION

Repeated CCl₄ gavage in rhesus monkeys results in stable liver fibrosis. Such a model may be an effective platform for future studies of human liver fibrosis.

Ischemic Postconditioning (IPostC) Protects Fibrotic and Cirrhotic Rat Livers after Warm Ischemia

BACKGROUND

Decreased organ function following liver resection is a major clinical issue. The practical method of ischemic postconditioning (IPostC) has been studied in heart diseases, but no data exist regarding fibrotic livers.

AIMS

We aimed to determine whether IPostC could protect healthy, fibrotic, and cirrhotic livers from ischemia reperfusion injury (IRI).

METHODS

Fibrosis was induced in male SD rats using bile duct ligation (BDL, 4 weeks), and cirrhosis was induced using thioacetamide (TAA, 18 weeks). Fibrosis and cirrhosis were histologically confirmed using HE and EvG staining. For healthy, fibrotic, and cirrhotic livers, isolated liver perfusion with 90 min of warm ischemia was performed in three groups (each with n=8): control, IPostC 8x20 sec, and IPostC 4x60 sec. additionally, healthy livers were investigated during a follow-up study. Lactate dehydrogenase (LDH) and thromboxane B₂ (TXB₂) in the perfusate, as well as bile flow (healthy/TAA) and portal perfusion pressure, were measured.

RESULTS

LDH and TXB₂ were reduced, and bile flow was increased by IPostC, mainly in total and in the late phase of reperfusion. The follow-up study showed that the perfusate derived from a postconditioned group had much less damaging potential than perfusate derived from the nonpostconditioned group.

CONCLUSION

IPostC following warm ischemia protects healthy, fibrotic, and cirrhotic livers against IRI. Reduced efflux of TXB₂ is one possible mechanism for this effect of IPostC and increases sinusoidal microcirculation. These findings may help to improve organ function and recovery of patients after liver resection.

MicroRNA-Based Prophylaxis in a Mouse Model of Cirrhosis and Liver Cancer

Most hepatocellular carcinomas (HCCs) arise in the context of chronic liver disease and/or cirrhosis. Thus, chemoprevention in individuals at risk represents an important but yet unproven approach. In this study, we investigated the ability of microRNA (miRNA)-based molecules to prevent liver cancer development in a cirrhotic model. To this end, we developed a mouse model able to recapitulate the natural progression from fibrosis to HCC, and then we tested the prophylactic activity of an miRNA-based approach in the model. The experiments were carried out in the TG221 transgenic mouse, characterized by the overexpression of miR-221 in the liver and predisposed to the development of liver tumors. TG221 as well as wild-type mice were exposed to the hepatotoxin carbon tetrachloride (CCl4) to induce chronic liver damage. All mice developed liver cirrhosis, but only TG221 mice developed nodular lesions in 100% of cases within 6 months of age. The spectrum of lesions ranged from dysplastic foci to carcinomas. To investigate miRNA-based prophylactic approaches, anti-miR-221 oligonucleotides or miR-199a-3p mimics were administered to TG221 CCl4-treated mice. Compared to control animals, a significant reduction in number, size, and, most significantly, malignant phenotype of liver nodules was observed, thus demonstrating an important prophylactic action of miRNA-based molecules. In summary, in this article, we not only report a simple model of liver cancer in a cirrhotic background but also provide evidence for a potential miRNA-based approach to reduce the risk of HCC development.

The therapeutic potential of induced hepatocyte-like cells generated by direct reprogramming on hepatic fibrosis

BACKGROUND

Until now, there is no effective anti-fibrotic therapy available for liver cirrhosis. Stem cell therapies have been studied for the treatment of hepatic fibrosis. However, the use of embryonic stem cells or induced pluripotent stem cells (iPSC) has limitations such as ethical concern or malignancy potential. Induced hepatocyte-like cells (iHEPs) generated by direct reprogramming technology may overcome these limitations.

METHODS

In this study, we generated iHEPs by direct reprogramming from mouse embryonic fibroblast (MEF) either using specific transcription factors such as c-Myc and Klf-4 (type A), or adding small molecules to HNF1α (type B).

RESULTS

We investigated the effect of iHEPs on acute liver injury and chronic hepatic fibrosis animal models induced by CCl₄ intra-peritoneal injection in BALB/C nude mice. In acute liver injury model, serum AST/ALT levels peaked at 24 h after CCl₄ injection. Intra-splenic transplantation of iHEPs significantly attenuated CCl₄-induced acute liver injury. GFP-labeled iHEPs (type A) migrated to the liver after intra-splenic transplantation that was confirmed by Western blotting and immunofluorescence staining. We found that GFP and albumin were co-localized in migrated iHEPs in the liver suggesting migrated iHEPs were functional. In chronic hepatic fibrosis mice experiment, transplantation of either type A or type B iHEPs significantly attenuated liver fibrosis induced by CCl₄ injection for 10 weeks.

CONCLUSIONS

Our study suggests that iHEPs may be used as a novel therapeutic strategy for the treatment of hepatic fibrosis.

The Role of S1P and the Related Signaling Pathway in the Development of Tissue Fibrosis

Tissue fibrosis, including pulmonary fibrosis, hepatic fibrosis, and cardiac fibrosis, is an important stage in the development of many diseases. It can lead to structural damage and dysfunction and even severe carcinogenesis or death. There is currently no effective method for the treatment of fibrosis. At present, the molecular mechanism of tissue fibrosis has not yet been fully elucidated, but many studies have demonstrated that it is involved in conveying the complex messages between fibroblasts and various cytokines. Sphingosine 1-phosphate (S1P) is a naturally bioactive sphingolipid. S1P and the related signaling pathways are important intracellular metabolic pathways involved in many life activities, including cell proliferation, differentiation, apoptosis, and cellular signal transduction. Increasing evidence suggests that S1P and its signaling pathways play an important role in the development of tissue fibrosis; however, the mechanisms of these effects have not yet been fully elucidated, and even the role of S1P and its signaling pathways are still controversial. This article focuses on the role of S1P and the related signaling pathways in the development of fibrosis of lung, liver, heart, and other tissues, with emphasis on the application of inhibitors of some of molecules in the pathway in clinical treatment of fibrosis diseases.

Treatment with Melatonin Improves Cognitive Behavior and Motor Skills in a Rat Model of Liver Fibrosis

INTRODUCTION AND AIM

Patients with liver cirrhosis (LC) and minimal hepatic encephalopaty have a higher accident rate. LC impairs the normal sleep-awake cycle and produces disturbances in behavior, cognition and motor skills. Abnormal melatonin (MT) levels have also been identified in LC. Administration of MT may regulate circadian rhythms and prevent the oxidative damage. We studied the effects of MT on spatial memory acquisition (SMA) and motor skills in a liver fibrosis model (LF)s.

MATERIALS AND METHODS

Forty-five rats, divided into 4 groups. [G1: LF; G2: LF + MT; G3: MT; G4: Healthy control (HC)]. LF was induced by carbon tetrachloride intraperitoneal injection (0.2 mL/kg) for 5 months. MT was administered during 5 weeks (0.4 mg/kg/day). SMA was evaluated by using the Morris Water Maze protocol where the escape latency (EL) and mean speed were measured. Data were registered by SMART®.

RESULTS

The EL measurement analyzed by two way ANOVA: cirrhosis presented a higher EL than controls or those treated with MT suggesting impaired memory acquisition which is rescued by MT treatment. The mean speed analysis revealed that LF presented higher speed than LF+MT or HC, suggesting that LF affects motor skills, which are improved by MT. To discard whether EL is affected by altered motor skills in LF treated with MT, we compared the average EL and speed between days 2 and 6 of the training protocol. Speed was not improved during the trials unlike EL, suggesting that memory acquisition is independent of motor skills.

CONCLUSION

These findings suggest that MT improves cognition and motor skills in the LF model.

Single versus double experimental bile duct ligation model for inducing bacterial translocation

BACKGROUND

Double common bile duct ligation plus section in rats is used as a model for bacterial translocation, a phenomenon that has been correlated with the degree of liver damage. This study analyzes whether a simpler variant of the technique is also a valid model to study bacterial translocation.

METHODS

Fifty-six male Sprague Dawley rats underwent one of three surgical interventions: a) proximal double ligation and section of the common bile duct; b) proximal simple ligation of the bile duct; and c) sham operation. Bacterial translocation was measured by cultures of mesenteric lymph nodes, blood, spleen and liver. Stool culture and histological analysis of liver damage were also performed.

RESULTS

The incidence of bacterial translocation in SBL and DBDL groups was 23,5% and 25% respectively. Mortality was similar between ligation groups (11.2% versus 10%). Liver cirrhosis developed in the group of double ligation and section (100% of the animals at 4 weeks), while portal hypertension appeared starting at week 3. None of the animals submitted to simple ligation developed liver cirrhosis.

CONCLUSIONS

Simple bile duct ligation is associated with a similar incidence of bacterial translocation as double ligation, but without cirrhosis or portal hypertension.

Gastrointestinal iron excretion and reversal of iron excess in a mouse model of inherited iron excess

The current paradigm in the field of mammalian iron biology states that body iron levels are determined by dietary iron absorption, not by iron excretion. Iron absorption is a highly regulated process influenced by iron levels and other factors. Iron excretion is believed to occur at a basal rate irrespective of iron levels and is associated with processes such as turnover of intestinal epithelium, blood loss, and exfoliation of dead skin. Here we explore iron excretion in a mouse model of iron excess due to inherited transferrin deficiency. Iron excess in this model is attributed to impaired regulation of iron absorption leading to excessive dietary iron uptake. Pharmacological correction of transferrin deficiency not only normalized iron absorption rates and halted progression of iron excess but also reversed body iron excess. Transferrin treatment did not alter the half-life of ⁵⁹Fe in mutant mice. ⁵⁹Fe-based studies indicated that most iron was excreted via the gastrointestinal tract and suggested that iron-loaded mutant mice had increased rates of iron excretion. Direct measurement of urinary iron levels agreed with ⁵⁹Fe-based predictions that urinary iron levels were increased in untreated mutant mice. Fecal ferritin levels were also increased in mutant mice relative to wild-type mice. Overall, these data suggest that mice have a significant capacity for iron excretion. We propose that further investigation into iron excretion is warranted in this and other models of perturbed iron homeostasis, as pharmacological targeting of iron excretion may represent a novel means of treatment for diseases of iron excess.

Animal models of cholestasis: An update on inflammatory cholangiopathies

Cholestasis is a frequent clinical condition initiating or complicating chronic liver diseases, particularly cholangiopathies, where the biliary epithelium is the primary target of the pathogenetic sequence. Until a few decades ago, understanding of cholestasis relied mostly on the experimental model of bile duct ligation in rodents. However, a simple model of biliary obstruction cannot reproduce the complex mechanisms and networks leading to cholestasis in cholangiopathies. These networks are underpinned by an intricate dysregulation of pro-inflammatory and pro-fibrotic signals involving besides cholangiocytes, multiple cell elements of both innate and adaptive immunity. Therefore, in the last years, a wide range of animal models of biliary injury have been developed, mostly in mice, following three main approaches, chemical induction, immunization and genetic manipulation. In this review, we will give an update of the animal models of the two main cholangiopathies, primary sclerosing cholangitis and primary biliary cholangitis, which have provided us with the most relevant insights into the pathogenesis of these still controversial diseases.

Hepatoprotective effect of Forsythiae Fructus water extract against carbon tetrachloride-induced liver fibrosis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Forsythia suspensa (Thunb.) Vahl, named Forsythiae Fructus (Lian-Qiao), is a well-known traditional Chinese medicine (TCM) used for clearing away heat and toxic material, eliminating the mass and relieving swelling.

AIM OF THE STUDY

This study aims to observe the attenuation of the water extract of Forsythiae Fructus (FSE) on carbon tetrachloride (CCl₄)-induced hepatic fibrosis in male C57BL/6 mice.

MATERIALS AND METHODS

Hepatic fibrosis was induced in male C57BL/6 mice by intraperitoneal injection with 2 ml/kg CCl₄ (mixed 1: 3 in olive oil) twice a week for 4 weeks. At the same time, the mice were orally given with FSE (1, 2 g/kg) every day for 4 weeks. Serum biochemical parameters, gene and protein expression related to liver fibrosis were analyzed. The contents of forsythiaside A and forsythin in FSE were measured by high-performance liquid chromatography (HPLC).

RESULTS

Results of serum alanine/aspartate aminotransferase (ALT/AST) activity and liver histological evaluation both showed the protection of FSE against CCl₄-induced liver injury. Further, the anti-fibrotic effects of FSE was evidenced by the results of Masson's trichrome and Sirius red staining, liver hydroxyproline content, and serum amounts of hyaluronic acid, laminin, collagen Ⅳ and type III procollagen (PCIII). FSE also reduced the expression of α-smooth muscle actin (α-SMA) in livers from CCl₄-injured mice. Additionally, FSE decreased the increased hepatic expression of fibroblast-specific protein 1 (FSP1) and vimentin induced by CCl₄ in mice.

CONCLUSIONS

FSE attenuates CCl₄-induced liver fibrosis in mice by inhibiting hepatic stellate cells (HSCs) activation, reducing hepatic extracellular matrix (ECM) disposition and reversing epithelial-mesenchymal transition (EMT).

Animal models to study bile acid metabolism

The use of animal models, particularly genetically modified mice, continues to play a critical role in studying the relationship between bile acid metabolism and human liver disease. Over the past 20 years, these studies have been instrumental in elucidating the major pathways responsible for bile acid biosynthesis and enterohepatic cycling, and the molecular mechanisms regulating those pathways. This work also revealed bile acid differences between species, particularly in the composition, physicochemical properties, and signaling potential of the bile acid pool. These species differences may limit the ability to translate findings regarding bile acid-related disease processes from mice to humans. In this review, we focus primarily on mouse models and also briefly discuss dietary or surgical models commonly used to study the basic mechanisms underlying bile acid metabolism. Important phenotypic species differences in bile acid metabolism between mice and humans are highlighted.

Genome‑wide identification of long noncoding RNAs in CCl4‑induced liver fibrosis via RNA sequencing

Liver fibrosis occurs as a result of chronic liver lesions, which may subsequently develop into liver cirrhosis and hepatocellular carcinoma. The involvement of long noncoding RNAs (lncRNAs) in liver fibrosis is being increasingly recognized. However, the exact mechanisms and functions of the majority of lncRNAs are poorly characterized. In the present study, the hepatotoxic substance carbon tetrachloride (CCl4) was employed to induce liver fibrosis in an animal model and agenome‑wide identification of lncRNAs in fibrotic liver tissues compared with CCl4 untreated liver tissues was performed using RNA sequencing. Sprague‑Dawley rats were treated with CCl4 for 8 weeks. Histopathogical alterations were observed in liver tissues, and serum levels of alanine aminotransferase, aspartate aminotransferase, transforming growth factor‑β1 and tumor necrosis factor‑α were significantly higher, in the CCl4‑treated group compared with the CCl4 untreated group. RNA sequencing of liver tissues demonstrated that 231 lncRNAs and 1,036 mRNAs were differentially expressed between the two groups. Furthermore, bioinformatics analysis demonstrated that the differentially expressed mRNAs were predominantly enriched in 'ECM‑receptor interaction', 'PI3K‑Akt signaling pathway' and 'focal adhesion' pathways, all of which are essential for liver fibrosis development. Validation of 12 significantly aberrant lncRNAs by reverse transcription‑quantitative polymerase chain reaction indicated that the expression patterns of 11 lncRNAs were consistent with the sequencing data. Furthermore, overexpression of lncRNA NR_002155.1, which was markedly downregulated in CCl4‑treated liver tissues, was demonstrated to inhibit HSC‑T6 cell proliferation in vitro. In conclusion, the present study determined the expression patterns of mRNAs and lncRNAs in fibrotic liver tissue induced by CCl4. The identified differentially expressed lncRNAs may serve as novel diagnostic biomarkers and therapeutic targets for liver fibrosis.

Hepatoprotective activity of Macrothelypteris torresiana (Gaudich.) aerial parts against CCl4-induced hepatotoxicity in rodents and analysis of polyphenolic compounds by HPTLC

Macrothelypteris torresiana is a fern species belonging to family Thelypteridaceae. The present study was conducted to evaluate hepatoprotective potential of ethanol extract from M. torresiana aerial parts (EEMTAP) and detect the polyphenolic compounds present in the extract using high performance thin layer chromatography (HPTLC). Hepatoprotective potential of EEMTAP were tested at doses of 300 and 600 mg/kg, per os (p.o.), on Wistar albino rats. The extract and silymarin treated animal groups showed significant decrease in activities of different biochemical parameters like serum glutamic oxaloacetic transaminase (SGOT), serum glutamate-pyruvate transaminase (SGPT), alkaline phosphatase (ALP), which were elevated by carbon tetrachloride (CCl₄) intoxication. The levels of total bilirubin and total protein alongwith the liver weight were also restored to normalcy by EEMTAP and silymarin treatment. After CCl₄ administration the level of hepatic antioxidant enzymes such as Glutathione (GSH) and Catalase (CAT) were decreased whereas the level of hepatic lipid peroxidation (LPO) was elevated. The level of these hepatic antioxidant enzymes were also brought to normalcy by EEMTAP and silymarin treatment. Histological studies supported the biochemical findings and treatment with EEMTAP at doses 300 and 600 mg/kg, p.o. was found to be effective in restoring CCl₄-induced hepatotoxicity in rats. A simple HPTLC analysis was conducted for the detection of polyphenolic compounds in EEMTAP, and the result revealed the presence of caffeic acid as phenolic acid and quercetin as flavonoid. The proposed HPTLC method is simple, concise and provides a good resolution of caffeic acid and quercetin from other constituents present in EEMTAP.

Activation of autophagy is required for Oroxylin A to alleviate carbon tetrachloride-induced liver fibrosis and hepatic stellate cell activation

Liver fibrosis is a reversible pathophysiological process correlated with intense repair and cicatrization mechanisms, and its end-stage cirrhosis is responsible for high morbidity and mortality worldwide. Interestingly, the use of natural products as a realistic option for the treatment of liver fibrosis has broadly been accepted. Oroxylin A, a safe and natural product, shows a wide range of pharmacological activities such as anti-inflammatory, anti-oxidant, and anti-tumor properties. However, the effects of Oroxylin A on liver fibrosis remain poorly understood. In the present study, we sought to determine the effect of Oroxylin A on carbon tetrachloride (CCl₄)-induced liver fibrosis, and to further examine the molecular mechanisms. We found that treatment with Oroxylin A markedly decreased the level of liver injury markers, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT), in a dose dependent manner. Moreover, Oroxylin A treatment remarkably inhibited extracellular matrix (ECM) deposition, and significantly down-regulated the mRNA and protein expression of liver fibrosis markers including α1(I)collagen, fibronectin, alpha-smooth muscle actin (α-SMA), PDGF-βR, and TGF-βR1 in CCl₄-induced murine model of liver fibrosis. Furthermore, experimental results in vitro showed that Oroxylin A treatment reduced the mRNA and protein expression of HSC activation markers, α-SMA, desmin, α1 (I) collagen, fibronectin, TGF-β, and TNF-α, in a dose dependent manner. Attractively, Oroxylin A treatment also markedly up-regulated the expression of autophagy makers, LC3-B, Atg3, Atg4, Atg5, Beclin1/Atg6, Atg7, Atg9, ATG12, and Atg14, and apparently reduced the expression of autophagy substrate p62 in both CCl₄-induced murine model of liver fibrosis and PDGF-BB-treated HSCs. Importantly, inhibition of autophagy by specific inhibitor 3-methyladenine (3-MA) completely abolished Oroxylin A-induced anti-fibrosis effect, indicating that activation of autophagy was required for Oroxylin A to alleviate liver fibrosis. Overall, these results provide novel implications to reveal the molecular mechanism of Oroxylin A-induced anti-fibrosis properties, by which points to the possibility of using Oroxylin A for the treatment of liver fibrosis.

Comparative restoration of acute liver failure by menstrual blood stem cells compared with bone marrow stem cells in mice model

BACKGROUND AIMS

The application of menstrual blood stem cells (MenSCs) in regenerative medicine is gaining increasing attention. The aim of this study was to investigate the therapeutic potential of MenSCs compared with bone marrow-derived stem cells (BMSCs) in an animal model of CCl₄-induced acute hepatic failure.

METHODS

Injured Balb/C mice were divided into multiple groups and received MenSCs, BMSCs or hepatocyte progenitor-like (HPL) cells derived from these cells.

RESULTS

Tracking of green fluorescent protein-labeled cells showed homing of cells in injured areas of the liver. In addition, the liver engraftment of MenSCs was shown by immunofluorescence staining using anti-human mitochondrial antibody. Microscopically examination, periodic acid-Schiff and Masson's trichrome staining of liver sections demonstrated the considerable liver regeneration post-cell therapy in all groups. Assessment of serum parameters including aspartate aminotransferase, alanine aminotransferase, total bilirubin, urea and cholesterol at day 7 exhibited significant reduction, such that this downward trend continued significantly until day 30. The restoration of liver biochemical markers, changes in mRNA levels of hepatic markers and the suppression of inflammatory markers were more significant in the MenSC-treated group compared with the BMSC-treated group. On the other hand, HPL cells in reference to undifferentiated cells had better effectiveness in the treatment of the acute liver injury.

CONCLUSIONS

Our data show that MenSCs may be considered an appropriate alternative stem cell population to BMSCs for treatment of acute liver failure.

A Novel Perspective on the ApoM-S1P Axis, Highlighting the Metabolism of ApoM and Its Role in Liver Fibrosis and Neuroinflammation

Hepatocytes, renal proximal tubule cells as well as the highly specialized endothelium of the blood brain barrier (BBB) express and secrete apolipoprotein M (apoM). ApoM is a typical lipocalin containing a hydrophobic binding pocket predominantly carrying Sphingosine-1-Phosphate (S1P). The small signaling molecule S1P is associated with several physiological as well as pathological pathways whereas the role of apoM is less explored. Hepatic apoM acts as a chaperone to transport S1P through the circulation and kidney derived apoM seems to play a role in S1P recovery to prevent urinal loss. Finally, polarized endothelial cells constituting the lining of the BBB express apoM and secrete the protein to the brain as well as to the blood compartment. The review will provide novel insights on apoM and S1P, and its role in hepatic fibrosis, neuroinflammation and BBB integrity.

Expression of classical mediators in hearts of rats with hepatic dysfunction

Liver cirrhosis is associated with impairment of cardiovascular function including alterations of the heart innervation, humoral and nervous dysregulation, changes in systemic circulation and electrophysiological abnormalities. Choline acetyltransferase (ChAT), enzyme forming acetylcholine, tyrosine hydroxylase (TH), and dopamine-β-hydroxylase (DBH), enzymes participating in noradrenaline synthesis, are responsible for the production of classical neurotransmitters, and atrial natriuretic peptide (ANP) is produced by cardiomyocytes. The aim of this study was to evaluate the influence of experimentally induced hepatic dysfunction on the expression of proANP, ChAT, TH, and DBH in the heart. Hepatic dysfunction was induced by application of thioacetamide (TAA) or by ligation of bile duct. Biochemical parameters of hepatic injury and levels of peroxidation in the liver and heart were measured. Liver enzymes measured in the plasma were significantly elevated. Cardiac level of peroxidation was increased in operated but not TAA group animals. In the left atrium of operated rats, the expression of TH and DBH was lower, while expression of ChAT remained unchanged. In TAA group, no significant differences in the expression of the genes compared to controls were observed. Liver injury induced by ligation leads to an imbalance in the intracardiac innervation, which might impair nervous control of the heart.

Animal models of biliary injury and altered bile acid metabolism

In the last 25years, a number of animal models, mainly rodents, have been generated with the goal to mimic cholestatic liver injuries and, thus, to provide in vivo tools to investigate the mechanisms of biliary repair and, eventually, to test the efficacy of innovative treatments. Despite fundamental limitations applying to these models, such as the distinct immune system and the different metabolism regulating liver homeostasis in rodents when compared to humans, multiple approaches, such as surgery (bile duct ligation), chemical-induced (3,5-diethoxycarbonyl-1,4-dihydrocollidine, DDC, α-naphthylisothiocyanate, ANIT), viral infections (Rhesus rotavirustype A, RRV-A), and genetic manipulation (Mdr2, Cftr, Pkd1, Pkd2, Prkcsh, Sec63, Pkhd1) have been developed. Overall, they have led to a range of liver phenotypes recapitulating the main features of biliary injury and altered bile acid metabolisms, such as ductular reaction, peribiliary inflammation and fibrosis, obstructive cholestasis and biliary dysgenesis. Although with a limited translability to the human setting, these mouse models have provided us with the ability to probe over time the fundamental mechanisms promoting cholestatic disease progression. Moreover, recent studies from genetically engineered mice have unveiled 'core' pathways that make the cholangiocyte a pivotal player in liver repair. In this review, we will highlight the main phenotypic features, the more interesting peculiarities and the different drawbacks of these mouse models. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Pro-fibrotic compounds induce stellate cell activation, ECM-remodelling and Nrf2 activation in a human 3D-multicellular model of liver fibrosis

Background & Aims

Currently most liver fibrosis research is performed in vivo, since suitable alternative in vitro systems which are able to recapitulate the cellular events leading to liver fibrosis are lacking. Here we aimed at generating a system containing cells representing the three key players of liver fibrosis (hepatocyte, Kupffer cells and stellate cells) and assess their response to pro-fibrotic compounds such as TGF-β1, methotrexate (MTX) and thioacetamide (TAA).

Methods

Human cell lines representing hepatocytes (HepaRG), Kupffer cell (THP-1 macrophages) and stellate cells (hTERT-HSC) were co-cultured using the InSphero hanging drop technology to generate scaffold-free 3D microtissues, that were treated with pro-fibrotic compounds (TGF-β1, MTX, TAA) for up to 14 days. The response of the microtissues was evaluated by determining the expression of cytokines (TNF-α, TGF-β1 and IL6), the deposition and secretion of ECM proteins and induction of gene expression of fibrosis biomarkers (e.g. αSMA). Induction of Nrf2 and Keap1, as key player of defence mechanism, was also evaluated.

Results

We could demonstrate that the multicellular 3D microtissue cultures could be maintained in a non-activated status, based on the low expression levels of activation markers. Macrophages were activated by stimulation with LPS and hTERT-HSC showed activation by TGF-β1. In addition, MTX and TAA elicited a fibrotic phenotype, as assessed by gene-expression and protein-deposition of ECM proteins such as collagens and fibronectin. An involvement of the antioxidant pathway upon stimulation with pro-fibrotic compounds was also observed.

Conclusion

Here, for the first time, we demonstrate the in vitro recapitulation of key molecular and cellular events leading to liver fibrosis: hepatocellular injury, antioxidant defence response, activation of Kupffer cells and activation of HSC leading to deposition of ECM.

Intrahepatic upregulation of MRTF-A signaling contributes to increased hepatic vascular resistance in cirrhotic rats with portal hypertension

BACKGROUND

Portal hypertension in cirrhosis is mediated, in part, by increased intrahepatic resistance, reflecting massive structural changes associated with fibrosis and intrahepatic vasoconstriction. Activation of the Rho/MRTF/SRF signaling pathway is essential for the cellular regulatory network of fibrogenesis. The aim of this study was to investigate MRTF-A-mediated regulation of intrahepatic fibrogenesis in cirrhotic rats.

METHODS

Portal hypertension was induced in rats via an injection of CCl₄ oil. Hemodynamic measurements were obtained using a polyethylene PE-50 catheter and pressure transducers. Expression of hepatic fibrogenesis was measured using histological staining. Expression of protein was measured using western blotting.

RESULTS

Upregulation of MRTF-A protein expression in the livers of rats with CCl₄-induced cirrhosis was relevant to intrahepatic resistance and hepatic fibrogenesis in portal hypertensive rats with increased modeling time. Inhibition of MRTF-A by CCG-1423 decelerated hepatic fibrosis, decreased intrahepatic resistance and portal pressure, and alleviated portal hypertension.

CONCLUSION

Increased intrahepatic resistance in rats with CCl₄-induced portal hypertension is associated with an upregulation of MRTF-A signaling. Inhibition of this pathway in the liver can decrease hepatic fibrosis and intrahepatic resistance, as well as reduce portal pressure in cirrhotic rats with CCl₄-induced portal hypertension.

Melatonin Alleviates Liver Apoptosis in Bile Duct Ligation Young Rats

Bile duct ligation (BDL)-treated rats display cholestasis and liver damages. The potential protective activity of melatonin in young BDL rats in terms of apoptosis, mitochondrial function, and endoplasmic reticulum (ER) homeostasis has not yet been evaluated. Three groups of young male Sprague-Dawley rats were used: one group received laparotomy (Sham), a second group received BDL for two weeks (BDL), and a third group received BDL and intraperitoneal melatonin (100 mg/day) for two weeks (BDL + M). BDL group rats showed liver apoptosis, increased pro-inflamamtory mediators, caspases alterations, anti-apoptotic factors changes, and dysfunction of ER homeostasis. Melatonin effectively reversed apoptosis, mainly through intrinsic pathway and reversed ER stress. In addition, in vitro study showed melatonin exerted its effect mainly through the melatonin 2 receptor (MT2) in HepG2 cells. In conclusion, BDL in young rats caused liver apoptosis. Melatonin rescued the apoptotic changes via the intrinsic pathway, and possibly through the MT2 receptor. Melatonin also reversed ER stress induced by BDL.

The Dimethylnitrosamine Induced Liver Fibrosis Model in the Rat

Four to six week old, male Wistar rats were used to produce animal models of liver fibrosis. The process requires four weeks of administration of 10 mg/kg dimethylnitrosamine (DMN), given intraperitoneally for three consecutive days per week. Intraperitoneal injections were performed in the fume hood as DMN is a known hepatoxin and carcinogen. The model has several advantages. Firstly, liver changes can be studied sequentially or at particular stages of interest. Secondly, the stage of liver disease can be monitored by measurement of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzymes. Thirdly, the severity of liver damage at different stages can be confirmed by sacrifice of animals at designated time points, followed by histological examination of Masson's Trichome stained liver tissues. After four weeks of DMN dosing, the typical fibrosis score is 5 to 6 on the Ishak scale. The model can be reproduced consistently and has been widely used to assess the efficacy of potential anti-fibrotic agents.

The Effect of rhCygb on CCl4-Induced Hepatic Fibrogenesis in Rat

This study aims to investigate whether the use of recombinant human cytoglobin (rhCygb) impact on hepatic fibrogenesis caused by CCl₄. SD (n = 150) rats were randomly divided into three groups of normal, CCl₄ model and rhCygb groups. After model establishment, rats in rhCygb groups were administered daily with rhCygb (2 mg/kg, s.c.). Histological lesions were staged according to metavir. Serum parameters including ALT, AST, HA, LN, Col III and Col IV were determined. The liver proteins were separated by 2-DE and identified. As a result, the stage of hepatic damage and liver fibrosis in rhCygb groups were significantly milder than that in CCl₄ model groups. Meanwhile, rhCygb dramatically reversed serum levels of ALT and AST, and also markedly decreased the liver fibrosis markers levels of LN, HA, Col III and Col IV. In 2-DE, 33 proteins among three groups with the same changing tendency in normal and rhCygb treated groups compared with CCl₄ model group were identified. GO analysis showed that several identified proteins involved in oxidative stress pathway. The study provides new insights and data for administration of rhCygb reversing CCl₄-induced liver fibrosis suggesting that rhCygb might be used in the treatment of liver fibrosis.

Hepatoprotective effect of orally applied water-soluble pristine C60 fullerene against CCl4-induced acute liver injury in rats

Oral administration of water-soluble pristine C₆₀ fullerene in small dose prevents acute liver injury caused by carbon tetrachloride in rats.

Chemical exchange saturation transfer (CEST) MR technique for in-vivo liver imaging at 3.0 tesla

PURPOSE

To evaluate Chemical Exchange Saturation Transfer (CEST) MRI for liver imaging at 3.0-T.

MATERIALS AND METHODS

Images were acquired at offsets (n = 41, increment = 0.25 ppm) from -5 to 5 ppm using a TSE sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified as the asymmetric magnetization transfer ratio (MTRasym) at 3.5 ppm and the total MTRasym integrated from 0.5 to 1.5 ppm, respectively, from the corrected Z-spectrum. Reproducibility was assessed for rats and humans. Eight rats were devoid of chow for 24 hours and scanned before and after fasting. Eleven rats were scanned before and after one-time CCl4 intoxication.

RESULTS

For reproducibility, rat liver APTw and GlycoCEST measurements had 95 % limits of agreement of -1.49 % to 1.28 % and -0.317 % to 0.345 %. Human liver APTw and GlycoCEST measurements had 95 % limits of agreement of -0.842 % to 0.899 % and -0.344 % to 0.164 %. After 24 hours, fasting rat liver APTw and GlycoCEST signals decreased from 2.38 ± 0.86 % to 0.67 ± 1.12 % and from 0.34 ± 0.26 % to -0.18 ± 0.37 % respectively (p < 0.05). After CCl4 intoxication rat liver APTw and GlycoCEST signals decreased from 2.46 ± 0.48 % to 1.10 ± 0.77 %, and from 0.34 ± 0.23 % to -0.16 ± 0.51 % respectively (p < 0.05).

CONCLUSION

CEST liver imaging at 3.0-T showed high sensitivity for fasting as well as CCl4 intoxication.

KEY POINTS

• CEST MRI of in-vivo liver was demonstrated at clinical 3 T field strength. • After 24-hour fasting, rat liver APTw and GlycoCEST signals decreased significantly. • After CCl4 intoxication both rat liver APTw and GlycoCEST signals decreased significantly. • Good scan-rescan reproducibility of liver CEST MRI was shown in healthy volunteers.