Comparison of three research models of portal hypertension in mice: macroscopic, histological and portal pressure evaluation

Endothelial Gab1 deficiency aggravates splenomegaly in portal hypertension independent of angiogenesis

Certain pathological changes, including angiogenesis, actively contribute to the pathogenesis of splenomegaly in portal hypertension (PH), although the detailed molecular and cellular mechanisms remain elusive. In this study, we demonstrated that endothelial Grb-2-associated binder 1 (Gab1) plays a negative role in PH-associated splenomegaly independent of angiogenesis. PH, which was induced by partial portal vein ligation, significantly enhanced Gab1 expression in endothelial cells in a time-dependent manner. Compared with controls, endothelium-specific Gab1 knockout (EGKO) mice exhibited a significant increase in spleen size while their PH levels remained similar. Pathological analysis indicated that EGKO mice developed more severe hyperactive white pulp and fibrosis in the enlarged spleen but less angiogenesis in both the spleen and mesenteric tissues. Mechanistic studies showed that the phosphorylation of endothelial nitric oxide synthase (eNOS) in EGKO mice was significantly lower than in controls. In addition, the dysregulation of fibrosis and inflammation-related transcription factors [e.g., Krüppel-like factor (KLF) 2 and KLF5] and the upregulation of cytokine genes (e.g., TNF-α and IL-6) were observed in EGKO mice. We thus propose that endothelial Gab1 mediates multiple pathways in inhibition of the pathogenesis of splenomegaly in PH via prevention of endothelial dysfunction and overproduction of proinflammatory/profibrotic cytokines.

A comparison of two common bile duct ligation methods to establish hepatopulmonary syndrome animal models

The major drawback of the current common bile duct ligation (CBDL)-induced hepatopulmonary syndrome (HPS) animal model is the extremely high mortality rate that hinders experimental studies. The purpose of this study was to investigate an improved method of CBDL with the goal of developing a simple and reproducible rat HPS model after a single CBDL treatment. Two groups of male Sprague–Dawley rats underwent separate methods of CBDL: (1) the upper common bile duct ligation (UCBDL) group ( n = 40), in which the first ligature was made near the junction of the hepatic ducts, and the second ligature was made above the entrance of the pancreatic duct; (2) the middle of the common bile duct ligation (MCBDL) group ( n = 40), in which the first ligature was made in the middle of the common bile duct, and the second ligature was made above the entrance of the pancreatic duct. The CBDL-induced HPS rats were evaluated by pulse oximeter, arterial blood analysis, histopathology, and cerebral uptake of intravenous technetium-99m-labeled albumin macroaggregates (which reflects intrapulmonary vascular dilation). The mortality rates of the UCBDL group and the MCBDL group were 42.5% and 77.5%, respectively ( P < 0.05). These results suggest that the UCBDL, a single improved procedure, provides a better method compared to the established HPS model, because of the relatively high success rate and the decreased risk of complications.

Role of Bone Marrow Mesenchymal Stem Cells in the Treatment of CCL4 Induced Liver Fibrosis in Albino Rats: A Histological and Immunohistochemical Study

BACKGROUND AND OBJECTIVES

Variety of pathological factors including viral hepatitis, alcohol and drug abuse, metabolic diseases, autoimmune diseases and congenital abnormalities can cause hepatic injury. Liver transplantation is the treatment of choice for end-stage liver diseases, however, it faces several difficulties. So the aim of the work is to evaluate the effect of bone marrow derived mesenchymal stem cells (BM-MSCs) on the liver structure in carbon tetra chloride CCL4 induced liver fibrosis in rats.

MATERIALS AND RESULTS

BM-MSCs were isolated and characterized from long bones of twenty male albino rats. Sixty female rats were divided into the following two groups: Group I; thirty rats which were the control group. Group II; thirty rats were injected intra-peritoneal (IP) by CCL4 twice weekly for four weeks and was further subdivided into the following three subgroups: Subgroup IIA (CCL4 alone); included ten rats which were sacrificed after this four weeks. Subgroup IIB (CCL4/MSCs); included ten rats which were IP injected by a single dose of BM-MSCs and were sacrificed after four weeks. Subgroup IIC (CCL4/recovery); included ten rats which were left for another four weeks without any intervention. Histological examination of liver specimens showed that CCl4 caused variable pathological changes with elevated liver enzymes. Injection of BM-MSCs revealed an improvement in the histological picture of the liver and its enzymatic profile. On the other hand, most of the pathological lesion were still detected in rats of recovery group.

CONCLUSIONS

BM-MSC could restore the liver structure and function in experimental model of liver fibrosis.

Monitoring of systemic and hepatic hemodynamic parameters in mice

The use of mouse models in experimental research is of enormous importance for the study of hepatic physiology and pathophysiological disturbances. However, due to the small size of the mouse, technical details of the intraoperative monitoring procedure suitable for the mouse were rarely described. Previously we have reported a monitoring procedure to obtain hemodynamic parameters for rats. Now, we adapted the procedure to acquire systemic and hepatic hemodynamic parameters in mice, a species ten-fold smaller than rats. This film demonstrates the instrumentation of the animals as well as the data acquisition process needed to assess systemic and hepatic hemodynamics in mice. Vital parameters, including body temperature, respiratory rate and heart rate were recorded throughout the whole procedure. Systemic hemodynamic parameters consist of carotid artery pressure (CAP) and central venous pressure (CVP). Hepatic perfusion parameters include portal vein pressure (PVP), portal flow rate as well as the flow rate of the common hepatic artery (table 1). Instrumentation and data acquisition to record the normal values was completed within 1.5 h. Systemic and hepatic hemodynamic parameters remained within normal ranges during this procedure. This procedure is challenging but feasible. We have already applied this procedure to assess hepatic hemodynamics in normal mice as well as during 70% partial hepatectomy and in liver lobe clamping experiments. Mean PVP after resection (n= 20), was 11.41 ± 2.94 cmH2O which was significantly higher (P<0.05) than before resection (6.87 ± 2.39 cmH2O). The results of liver lobe clamping experiment indicated that this monitoring procedure is sensitive and suitable for detecting small changes in portal pressure and portal flow rate. In conclusion, this procedure is reliable in the hands of an experienced micro-surgeon but should be limited to experiments where mice are absolutely needed.

Pathological changes in pulmonary circulation in carbon tetrachloride (CCl4)-induced cirrhotic mice

RATIONALE

Lack of an experimental model of portopulmonary hypertension (POPH) has been a major obstacle in understanding of pathophysiological mechanisms underlying the disease.

OBJECTIVE

We investigated the effects of CCl4-mediated cirrhosis on the pulmonary vasculature, as an initial step towards an improved understanding of POPH.

METHODS AND RESULTS

Male C57BL/6 mice received intraperitoneal injection of either sterile olive oil or CCl4 3 times/week for 12 weeks. Cirrhosis and portal hypertension were confirmed by evidence of bridging fibrosis and nodule formation in CCl4-treated liver determined by trichrome/picrosirius red staining and an increase in spleen weight/body weight ratio, respectively. Staining for the oxidative stress marker, 4-hydroxynonenal (4-HNE), was strong in the liver but was absent in the lung, suggesting that CCl4 did not directly induce oxidative injury in the lung. Pulmonary acceleration time (PAT) and the ratio of PAT/pulmonary ejection time (PET) measured by echocardiography were significantly decreased in cirrhotic mice. Increase in right ventricle (RV) weight/body weight as well as in the weight ratio of RV/(left ventricle + septum) further demonstrated the presence of pathological changes in the pulmonary circulation in these mice. Histological examination revealed that lungs of cirrhotic mice have excessive accumulation of perivascular collagen and thickening of the media of the pulmonary artery.

CONCLUSION

Collectively, our data demonstrate that chronic CCl4 treatment induces pathological changes in pulmonary circulation in cirrhotic mice. We propose that this murine cirrhotic model provides an exceptional tool for future studies of the molecular mechanisms mediating pulmonary vascular diseases associated with cirrhosis and for evaluation of novel therapeutic interventions.

Evaluation of liver fibrosis and hepatic venous pressure gradient with MR elastography in a novel swine model of cirrhosis

PURPOSE

To assess the correlation among MR elastography (MRE) measured liver stiffness (LS), liver fibrosis, and hepatic venous pressure gradient (HVPG) in a swine model of cirrhosis.

MATERIALS AND METHODS

Three swine served as controls, and liver fibrosis was induced in eight swine by transarterial embolization. LS and HVPG were obtained at baseline and 4 weeks (prenecropsy) following induction of liver fibrosis.

RESULTS

Four weeks following the induction of liver cirrhosis, experimental animals developed an increase in HVPG of 8.0±6.4 mmHg compared with 0.3±1.2 mmHg for controls (P=0.08). Over the same timeframe, mean MRE-measured LS increased 0.82±0.39 kPa for experimental swine and 0.1±0.05 kPa for controls (P=0.01). A positive correlation was observed between increases in HVPG and LS (ρ=0.682; P=0.02). Liver fibrosis was measured on explanted livers at 4 weeks and yielded mean fibrosis scores of 2.8 for experimental animals and 0 for controls (P=0.0016). A positive correlation was observed between higher LS and liver fibrosis (ρ=0.884; P=0.0003).

CONCLUSION

MRE is a reliable noninvasive technique to measure LS in a swine model of cirrhosis. Significant positive correlations were observed between LS and HVPG as well as LS and fibrosis.

Involvement of opioidergic and nitrergic systems in memory acquisition and exploratory behaviors in cholestatic mice

Bile duct ligation (BDL) is an animal model used in cholestatic disease research. Both opioidergic and nitrergic systems are known to be involved in cholestasis. The aim of this study was to investigate the possible interaction between these two systems in BDL-induced memory formation and exploratory behaviors in mice. Male mice weighing 25-30 g were divided into nonoperated controls, sham-operated, and BDL groups. One-trial step-down and hole-board paradigms were used to assess memory acquisition and exploratory behaviors, respectively. Cholestasis did not alter memory acquisition while increasing exploratory behaviors 7 days after BDL. A pretraining intraperitoneal injection of L-arginine (50, 100, and 200 mg/kg), L-NG-nitroarginine methyl ester (L-NAME) (5, 10, 20, and 40 mg/kg), or naloxone (0.125, 0.25, and 0.5 mg/kg) did not alter memory acquisition or exploratory behaviors, whereas morphine (5 and 7.5 mg/kg) decreased memory acquisition in sham-operated animals. Moreover, although injection of L-NAME and naloxone exerted no effect on memory acquisition in the 7 days post-BDL mice, L-arginine (100 and 200 mg/kg) and morphine (2.5, 5, and 7.5 mg/kg) injection reduced it. In contrast, L-NAME and naloxone, but not morphine or L-arginine, reduced the BDL-induced exploratory behaviors. Coadministration of subthreshold doses of morphine (1.25 mg/kg) and L-arginine (50 mg/kg) caused a memory deficit in 7 days post-BDL mice. However, the memory deficit induced by the effective doses of morphine (2.5 mg/kg) or L-arginine (200 mg/kg) in these mice was restored by the administration of either naloxone (0.5 mg/kg) or L-NAME (40 mg/kg). In addition, naloxone and L-NAME reduced the exploratory behaviors in L-arginine-pretreated mice but not in morphine-pretreated mice. We conclude that there appears to be a synergistic effect between opioidergic and nitrergic systems on memory acquisition and exploratory behaviors in cholestatic mice.

Synergistic effects between CA1 mu opioid and dopamine D1-like receptors in impaired passive avoidance performance induced by hepatic encephalopathy in mice

BACKGROUND AND AIM

Numerous investigations have indicated that hepatic encephalopathy (HE) alters the levels of various neurotransmitters. However, comprehensive data regarding the effects of CA1 opioidergic and dopaminergic (DAergic) systems on HE-induced amnesia are still lacking.

METHODS

Following intra-dorsal hippocampal (CA1) injection of mu opioid and dopamine D1- and D2-like receptors antagonists in male mice, one-trial step-down and hole-board paradigms were used to assess memory and exploratory behaviors, respectively.

RESULTS

Our data demonstrated that HE impairs memory 24 days after bile duct ligation (BDL). Furthermore, while the higher dose of DA D1-like receptor antagonist (SCH23390, 0.5 μg/mouse) induced amnesia and anxiogenic-like behaviors, mu receptor antagonist (naloxone: 0.0125, 0.025 and 0.05 μg/mouse) and DA D2-like receptor antagonist (sulpiride: 0.0625, 0.125 and 0.25 μg/mouse) by themselves, could not exert an effect on memory performance in passive avoidance task. On the other hand, pre-test injection of all drugs reversed the HE-induced amnesia 24 days after BDL, while having no effect on exploratory behaviors. Pre-test co-administration of the subthreshold dose SCH23390 (0.25 μg/mouse) and sulpiride (0.0625 μg/mouse) or naloxone (0.0125 μg/mouse) could likewise reverse the BDL-induced amnesia. However, when the subthreshold sulpiride plus naloxone were co-administered, BDL-induced amnesia was not blocked.

CONCLUSIONS

Memory performance is impaired 24 days post BDL and CA1 mu opioid and DA D1-like receptors antagonist synergistic effects are likely involved in this phenomenon.

Animal models of chronic liver diseases

Chronic liver diseases are frequent and potentially life threatening for humans. The underlying etiologies are diverse, ranging from viral infections, autoimmune disorders, and intoxications (including alcohol abuse) to imbalanced diets. Although at early stages of disease the liver regenerates in the absence of the insult, advanced stages cannot be healed and may require organ transplantation. A better understanding of underlying mechanisms is mandatory for the design of new drugs to be used in clinic. Therefore, rodent models are being developed to mimic human liver disease. However, no model to date can completely recapitulate the "corresponding" human disorder. Limiting factors are the time frame required in humans to establish a certain liver disease and the fact that rodents possess a distinct immune system compared with humans and have different metabolic rates affecting liver homeostasis. These features account for the difficulties in developing adequate rodent models for studying disease progression and for testing new pharmaceuticals to be translated into the clinic. Nevertheless, traditional and new promising animal models that mimic certain attributes of chronic liver diseases are established and being used to deepen our understanding in the underlying mechanisms of distinct liver diseases. This review aims at providing a comprehensive overview of recent advances in animal models recapitulating different features and etiologies of human liver diseases.

The lung in liver disease: old problem, new concepts

Liver dysfunction has been recognized to influence the lung in many different clinical situations, although the mechanisms for these effects are not well understood. One increasingly recognized interaction, the hepatopulmonary syndrome (HPS) occurs in the context of cirrhosis and results when alveolar microvascular dilation causes arterial gas exchange abnormalities and hypoxemia. HPS occurs in up to 30% of patients with cirrhosis and significantly increases mortality in affected patients. Currently, liver transplantation is the only curative therapy. Experimental biliary cirrhosis induced by common bile duct ligation (CBDL) in the rat reproduces the pulmonary vascular and gas exchange abnormalities of human HPS and has been contrasted with other experimental models of cirrhosis in which HPS does not develop. Microvascular dilation, intravascular monocyte infiltration, and angiogenesis in the lung have been identified as pathologic features that drive gas exchange abnormalities in experimental HPS. Our recent studies have identified biliary epithelium and activation and interaction between the endothelin-1 (ET-1)/endothelial endothelin B (ETB) receptor and CX3CL1/CX3CR1 pathways as important mechanisms for the observed pathologic events. These studies define novel interactions between the lung and liver in cirrhosis and may lead to effective medical therapies.

Dietary honey and ginseng protect against carbon tetrachloride-induced hepatonephrotoxicity in rats

Liver diseases are amongst the most serious health problems in the world today and hepatocellular carcinoma is one of the world's deadliest cancers. The aim of the current study was to evaluate the protective effect of sider honey and/or Korean ginseng extract (KGE) against carbon tetrachloride (CCl(4))-induced hepato-nephrotoxicity in rat. Eighty male Sprague-Dawley (SD) rats were allocated into different groups and over a 4-week period, they orally received honey and/or KGE or were treated either with CCl(4) alone (100 mg/kg b.w) or with CCl(4) after a pretreatment period with honey, KGE or a combination of both. Clinical, clinico-pathological and histopathological evaluations were done and CCl(4)-treated groups were compared with rats receiving no treatment and with rats given honey, KGE or a combination of these substances. The results indicated that oral administration of CCl(4) induced severe hepatic and kidney injury associated with oxidative stress. The combined treatment with CCl(4) plus honey and/or KGE resulted in a significant improvement in all evaluated parameters. This improvement was prominent in the group receiving CCl(4) after combined pretreatment with honey and KGE. Animals receiving honey and/or KGE (without CCl(4)-treatment) were comparable to the control untreated group. It could be concluded that honey and KGE protect SD rats against the severe CCl(4)-induced hepatic and renal toxic effects. Our results suggest that the protective activity of honey and KGE may have been related to their antioxidant properties.

Hepatopulmonary syndrome: update on pathogenesis and clinical features

Hepatopulmonary syndrome (HPS) is a serious vascular complication of liver disease that occurs in 5-32% of patients with cirrhosis. The presence of HPS markedly increases mortality. No effective medical therapies are currently available and liver transplantation is the only established treatment option for HPS. The definition and diagnosis of HPS are established by the presence of a triad of liver disease with intrapulmonary vascular dilation that causes abnormal arterial gas exchange. Experimental biliary cirrhosis induced by common bile duct ligation in the rat reproduces the pulmonary vascular and gas exchange abnormalities of human HPS and serves as a pertinent animal model. Pulmonary microvascular dilation and angiogenesis are two central pathogenic features that drive abnormal pulmonary gas exchange in experimental HPS, and thus might underlie HPS in humans. Defining the mechanisms involved in the microvascular alterations of HPS has the potential to lead to effective medical therapies. This Review focuses on the current understanding of the pathogenesis, clinical features and management of HPS.

Animal models of cutaneous and hepatic fibrosis

Fibrosis occurs as a part of normal wound healing. However, excessive or dysregulated fibrosis can lead to severe organ dysfunction and is a feature of a variety of diseases. Due to its insidious onset, fibrosis tends to go undetected in its early stages. This is in part why these diseases remain so poorly understood. Animal models have provided a means to examine these early stages and to isolate and understand the effect of perturbations in signaling pathways, chemokines, and cytokines. Here, we summarize recent progress in the understanding of the molecular pathogenesis of fibrosis, both its initiation and its maintenance phases, from animal models of fibrosis in the skin and liver. Due to these organs' properties, modeling fibrosis in them poses unique challenges. Elegant solutions have therefore been developed for modeling fibrosis in each, and now, great potential for animal models to contribute to our understanding appears scientifically imminent.

Portal hypertension correlates with splenic stiffness as measured with MR elastography

PURPOSE

To investigate the correlation between MR elastography (MRE) assessed spleen stiffness and direct portal vein pressure gradient (D-HVPG) measurements in a large animal model of portal hypertension.

MATERIALS AND METHODS

Cholestatic liver disease was established in adult canines by common bile duct ligation. A spin echo based echo planar imaging (EPI) MRE sequence was used to acquire three-dimensional/three axis (3D/3-axis) abdominal MRE data at baseline, 4 weeks, and 8 weeks. Liver biopsies, blood samples, and D-HVPG measurements were obtained simultaneously.

RESULTS

Animals developed portal hypertension (D-HVPG: 11.0 ± 5.1 mmHg) with only F1 fibrosis after 4 weeks. F3 fibrosis was confirmed after 8 weeks despite no further rise in portal hypertension (D-HVPG: 11.3 ± 3.2 mmHg). Mean stiffnesses of the spleen increased over two-fold from baseline (1.72 ± 0.33 kPa) to 4 weeks (3.54 ± 0.31 kPa), and stabilized at 8 weeks (3.38 ± 0.06 kPa) in a pattern consistent with changes in portal pressure. A positive correlation was observed between spleen stiffness and D-HVPG (r(2) = 0.86; P < 0.01).

CONCLUSION

These findings indicate a temporal relationship between portal hypertension and the development of liver fibrosis in a large animal model of cholestatic liver disease. The observed direct correlation between spleen stiffness and D-HVPG suggest a noninvasive MRE approach to diagnose and screen for portal hypertension.

Alterations of serum protein N-glycosylation in two mouse models of chronic liver disease are hepatocyte and not B cell driven

N-glycosylation of immunoglobulin G (IgG) has an important impact on the modification of the total serum N-glycome in chronic liver patients. Our aim was to determine the role and magnitude of the alterations in which hepatocytes and B cells are involved in two mouse models of chronic liver disease. Common bile duct ligation (CBDL) and subcutaneous injections with CCl(4) were induced in B cell-deficient and wild-type (WT) mice. IgG depletion was performed with beads covered with protein A/G and the depletions were evaluated by SDS-PAGE and Western blot analysis. N-glycan analysis was performed by improved DSA-FACE technology. Structural analysis of the mouse serum N-glycans was performed by exoglycosidase digests and MALDI-TOF mass spectrometry of permethylated glycans. The alterations seen in B cell-deficient mice closely resembled the alterations in WT mice, in both the CBDL and the CCl(4) models. N-glycan analysis of the IgG fraction in both mouse models revealed different changes compared with humans. Overall, the impact of IgG glycosylation on total serum glycosylation was marginal. Interestingly, the amount of fibrosis present in CBDL B cell-deficient mice was significantly increased compared with CBDL WT mice, whereas the opposite was true for the CCl(4) model as determined by Sirius red staining. However, this had no major effect on the alteration of N-glycosylation of serum proteins. Alterations of total serum N-glycome in mouse models of chronic liver disease are hepatocyte-driven. Undergalactosylation of IgG is not present in mouse models of chronic liver disease.

Animal models for the study of hepatic fibrosis

Animal models are being used for several decades to study fibrogenesis and to evaluate the anti-fibrotic potential of therapies and strategies. Although immensely valuable for our understanding of pathophysiological processes, they remain models and none of them reproduces a human disease. Each model (meaning stimulus, design, strain and species) displays specific characteristics in the nature of the pathogenesis, the topography and the evolution of fibrosis. We review here the most used as well as some newly described but potentially interesting models including models for studying biliary, immune, alcohol-induced, NASH-associated and viral fibrosis and provide insight on underlying disease processes and practical details. We attempted to delineate the benefits, advantages, limitations and drawbacks of those models. We also report the new opportunities provided by genetically engineered mice for tracking and manipulating cells that participate to fibrosis. Finally, we emphasize the importance of adapting study design to the question addressed.

Vascular corrosion casting: analyzing wall shear stress in the portal vein and vascular abnormalities in portal hypertensive and cirrhotic rodents

Vascular corrosion casting is an established method of anatomical preparation that has recently been revived and has proven to be an excellent tool for detailed three-dimensional (3D) morphological examination of normal and pathological microcirculation. In addition, the geometry provided by vascular casts can be further used to calculate wall shear stress (WSS) in a vascular bed using computational techniques. In the first part of this study, the microvascular morphological changes associated with portal hypertension (PHT) and cirrhosis in vascular casts are described. The second part of this study consists of a quantitative analysis of the WSS in the portal vein in casts of different animal models of PHT and cirrhosis using computational fluid dynamics (CFD). Microvascular changes in the splanchnic, hepatic and pulmonary territory of portal hypertensive and cirrhotic mice are described in detail with stereomicroscopic examination and scanning electron microscopy. To our knowledge, our results are the first to report the vascular changes in the common bile duct ligation cirrhotic model. Calculating WSS using CFD methods is a feasible technique in PHT and cirrhosis, enabling the differentiation between different animal models. First, a dimensional analysis was performed, followed by a CFD calculation describing the spatial and temporal WSS distributions in the portal vein. WSS was significantly different between sham/cirrhotic/pure PHT animals with the highest values in the latter. Up till now, no techniques have been developed to quantify WSS in the portal vein in laboratory animals. This study showed for the first time that vascular casting has an important role not only in the morphological evaluation of animal models of PHT and cirrhosis, but also in defining the biological response of the portal vein wall to hemodynamic changes. CFD in 3D geometries can be used to describe the spatial and temporal variations in WSS in the portal vein and to better understand the forces affecting mechanotransduction in the endothelium.

Morphological and molecular pathology of CCL4-induced hepatic fibrosis in connexin43-deficient mice

Gap junction channels, formed by connexins (Cx), are involved in the maintenance of tissue homeostasis, cell growth, differentiation, and development. Several studies have shown that Cx43 is involved in the control of wound healing in dermal tissue. However, it remains unknown whether Cx43 plays a role in the control of liver fibrogenesis. Our study investigated the roles of Cx43 heterologous deletion on carbon tetrachloride (CCl(4))-induced hepatic fibrosis in mice. We administered CCl(4) to both Cx43-deficient (Cx43(+/-)) and wild-type mice and examined hepatocellular injury and collagen deposition by histological and ultrastructural analyses. Serum biochemical analysis was performed to quantify liver injury. Hepatocyte proliferation was analyzed immunohistochemically. Protein and messenger RNA (mRNA) expression of liver connexins were evaluated using immunohistochemistry as well as immunoblotting analysis and quantitative real-time PCR. We demonstrated that Cx43(+/-) mice developed excessive liver fibrosis compared with wild-type mice after CCl(4) -induced chronic hepatic injury, with thick and irregular collagen fibers. Histopathological evaluation showed that Cx43(+/-) mice present less necroinflammatory lesions in liver parenchyma and consequent reduction of serum aminotransferase activity. Hepatocyte cell proliferation was reduced in Cx43(+/-) mice. There was no difference in Cx32 and Cx26 protein or mRNA expression in fibrotic mice. Protein expression of Cx43 increased in CCl(4)-treated mice, although with aberrant protein location on cytoplasm of perisinusoidal cells. Our results demonstrate that Cx43 plays an important role in the control and regulation of hepatic fibrogenesis.

Impact of elevation of total bilirubin level and etiology of the liver disease on serum N-glycosylation patterns in mice and humans

The GlycoFibroTest and GlycoCirrhoTest are noninvasive alternatives for liver biopsy that can be used as a follow-up tool for fibrosis patients and to diagnose cirrhotic patients, respectively. These tests are based on the altered N-glycosylation of total serum protein. Our aim was to investigate the impact of etiology on the alteration of N-glycosylation and whether other characteristics of liver patients could have an influence on N-glycosylation. In human liver patients, no specific alteration could be found to make a distinction according to etiological factor, although alcoholic patients had a significant higher mean value for the GlycoCirrhoTest. Undergalactosylation did not show a significantly different quantitative alteration in the cirrhotic and noncirrhotic population of all etiologies. Importantly, patients with an elevation of total bilirubin level (>2 mg/dl) had a strong increase of glycans modified with alpha1-6 fucose. The fucosylation index was therefore significantly higher in fibrosis/cirrhosis and hepatocellular carcinoma patients with elevated total bilirubin levels irrespective of etiology. Furthermore, in a multiple linear regression analysis, only markers for cholestasis significantly correlated with the fucosylation index. In mouse models of chronic liver disease, the fucosylation index was uniquely significantly increased in mice that were induced with a common bile duct ligation. Mice that were chronically injected with CCl(4) did not show this increase. Apart from this difference, common changes characteristic to fibrosis development in mice were observed. Finally, mice induced with a partial portal vein ligation did not show biological relevant changes indicating that portal hypertension does not contribute to the alteration of N-glycosylation.

A canine portal hypertension model induced by intra-portal administration of Sephadex microsphere

BACKGROUND AND AIM

Big animal models of portal hypertension are important for the research into this disease. The aim of this study was to establish a canine portal hypertension model by intra-portal administration of microspheres.

METHODS

Sixteen mongrel dogs were assigned to control group and experimental group randomly. The catheterization of portal vein was performed by laparotomy and the outer end of the catheter was fixed subcutaneously in the abdominal wall. The dogs of the experimental group were given intra-portal injections of microspheres at a five-day interval, six times in total. Portal hemodynamics, blood cell counting, liver and renal function test, portography, gastroscopy, liver, spleen and lung histological examination were taken to evaluate the model.

RESULTS

1, 2, 3 and 4 months after initial injection of microspheres, portal venous pressure rose from baseline 8.7 +/- 0.7 mmHg to 24.3 +/- 1.6, 20.6 +/- 2.1, 19.0 +/- 1.8 and 17.7 +/- 2.0 mmHg, respectively (P < 0.01). The diameter of portal vein increased from 7.6 +/- 0.3 to 8.6 +/- 0.3 mm, calculated portal resistance increased from 0.46 +/- 0.06 to 1.06 +/- 0.20 (mmHg/mL/min/kg body weight); velocity of portal blood flow decreased from 35.1 +/- 1.7 to 26.1 +/- 2.4 cm/s (P < 0.01, respectively). The animals of experimental group developed marked splenomegaly and profuse portosystemic collateral circulations with normal liver and renal function.

CONCLUSION

Repeated intra-portal administration of microspheres can induce stable and reproducible chronic portal hypertension in dogs with normal liver and renal functions. This model can meet multiple demands of both basic and clinical research of portal hypertension.

A real-time, telemetric method for continuous measurement of portal pressures

The ability to longitudinally monitor portal and splanchnic pressures would greatly enhance the understanding of acute and chronic liver disease by helping to assess the immediate and long-term impact of therapeutic manipulations. However, a technique for measuring portal pressures in the ambulatory setting is not currently available. To overcome this difficulty, we utilized an approach that involved the implantation of a miniature telemetric device, equipped with a specially-designed pressure transmission catheter, into the spleen of an anesthetized mouse. Using this approach, portal pressures were measured continuously over 5 d in conscious, unrestrained animals, the availability of which will help facilitate studies of the portal circulation requiring long-term stability.

A novel model of CCl4-induced cirrhosis with ascites in the mouse

BACKGROUND/AIMS

The current approaches to study the molecular mechanisms involved in the pathophysiology of liver diseases often rely on the use of transgenic mice. However, experimental models of decompensated cirrhosis have not been clearly established in mice. Thus, we aimed to set an efficient and well-tolerated protocol to induce cirrhosis in mice able to progress up to the ascitic stage.

METHODS

C57BL/6N mice received CCl(4) subcutaneously, intraperitoneally or by inhalation. In the latter group, gaseous CCl(4) was administered according to three different schedules: increasing exposure times, twice weekly (traditional protocol; TP), short inhalation cycles, twice or three times weekly.

RESULTS

Portal hypertension, sodium retention, and ascites developed in all groups between 11 and 15 weeks. Mortality reached 70% in the TP group, but it was only 0-10% with all other protocols. All the inhalation groups had significantly more ascites at sacrifice than those receiving CCl(4) subcutaneously and intraperitoneally. Extensive abdominal adhesions and evidence of enhanced hepatic inflammation, as suggested by the increased gene expression of pro-inflammatory cytokines in liver tissue, were found in the intraperitoneal group, while large granulomas at the injection site and marked neutrophil infiltration of lungs developed in the subcutaneous group. No extra-hepatic damage could be detected in mice inhaling CCl(4).

CONCLUSIONS

The use of short cycles of CCl(4) inhalation represents a novel, safe, and effective method to induce decompensated cirrhosis in mice. Intraperitoneal CCl(4) leads instead to abdominal adhesions precluding a correct evaluation of ascites, while subcutaneous CCl(4) causes an unwanted systemic inflammatory response.

Role of placental growth factor in mesenteric neoangiogenesis in a mouse model of portal hypertension

BACKGROUND & AIMS

Portal hypertension is responsible for the major complications associated with cirrhosis. Angiogenesis has been associated with the pathophysiology of portal hypertension. We investigated the role of placental growth factor (PlGF) and tested the effects of monoclonal antibodies against PlGF (alphaPlGF) in a mouse model of portal hypertension.

METHODS

Using a mouse model of prehepatic portal hypertension, we measured PlGF levels in the mesenteric tissue at different time points. We used knockout mice and alphaPlGF to determine the role of PlGF in the splanchnic hyperdynamic system and portosystemic collateral formation, examining its effects before and after portal hypertension was induced.

RESULTS

PlGF was significantly up-regulated in the mesenteric tissue of mice with portal hypertension. Compared with wild-type animals, the vascular density in the mesentery was reduced in PlGF knockout hypertensive mice, preventing collateral formation and attenuation of mesenteric artery flow without affecting portal pressure. In the prevention study, alphaPlGF showed similar findings as in the knockout study. In mice with portal hypertension, administration of alphaPlGF resulted in a 32% decrease in portal pressure, compared with mice given immunoglobulin G(1) (control).

CONCLUSIONS

Pathologic angiogenesis in the mesenteric tissues of mice with portal hypertension is mediated by PlGF. Blocking PlGF could be an effective strategy for reducing collateral formation and lowering portal pressure; further research into the effects in cirrhosis is warranted.

Bile duct ligation in rats: A reliable model of hepatorenal syndrome?

The two most widely used experimental models of advanced liver disease are the administration of carbon tetrachloride, and common bile duct ligation (BDL), however, neither has been systematically evaluated as a model of hepatorenal syndrome (HRS). The BDL model in rats, studied at diverse time points, induced a progressive renal dysfunction without structural changes in the kidney. The authors concluded that BDL is a good model for further studies of HRS and its treatment. However, the renal impairment observed at the acute phase of the BDL model is based on a different pathophysiology than that of HRS. Specifically, in acute obstructive jaundice, cholemia predominates over parenchymal liver disease (reversible at this stage without portal hypertension or cirrhosis) and independently induces negative inotropic and chronotropic effects on the heart, impaired sympathetic vasoconstriction response and profound natriuresis and diuresis that might lead to volume depletion. In addition, systemic endotoxemia contributes to the prerenal etiology of renal impairment and promotes direct nephrotoxicity and acute tubular necrosis. On the other hand, the renal failure observed in the chronic BDL model (with development of biliary cirrhosis, portal hypertension and ascites) shares pathophysiological similarities with HRS, but the accordance of the chronic BDL model to the diagnostic criteria of HRS (e.g. absence of spontaneous bacterial peritonitis, no renal function improvement after plasma volume expansion) should have been confirmed. In conclusion, we think that the BDL model is not suitable for the study of the natural history of HRS, but the chronic BDL model might be valid for the study of established HRS and its potential therapies.