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

Hepatic BMAL1 and HIF1α regulate a time-dependent hypoxic response and prevent hepatopulmonary-like syndrome

The transcriptional response to hypoxia is temporally regulated, yet the molecular underpinnings and physiological implications are unknown. We examined the roles of hepatic Bmal1 and Hif1α in the circadian response to hypoxia in mice. We found that the majority of the transcriptional response to hypoxia is dependent on either Bmal1 or Hif1α, through shared and distinct roles that are daytime determined. We further show that hypoxia-inducible factor (HIF)1α accumulation upon hypoxia is temporally regulated and Bmal1 dependent. Unexpectedly, mice lacking both hepatic Bmal1 and Hif1α are hypoxemic and exhibit increased mortality upon hypoxic exposure in a daytime-dependent manner. These mice display mild liver dysfunction with pulmonary vasodilation likely due to extracellular signaling regulated kinase (ERK) activation, endothelial nitric oxide synthase, and nitric oxide accumulation in lungs, suggestive of hepatopulmonary syndrome. Our findings indicate that hepatic BMAL1 and HIF1α are key time-dependent regulators of the hypoxic response and can provide molecular insights into the pathophysiology of hepatopulmonary syndrome.

Synergistic Hepatoprotective Effects of Mesenchymal Stem Cells and Platelet-Rich Plasma in a Rat Model of Bile Duct Ligation-Induced Liver Cirrhosis

Liver cirrhosis poses a global health challenge marked by significant prevalence and mortality. Current therapeutic options are limited by high costs and immune-mediated rejection, necessitating the exploration of innovative strategies to enhance hepatic self-rehabilitation, and counteract the underlying pathological mechanisms. We evaluated the hepatoprotective activity of rat adipose-derived mesenchymal stem cells (ADMSCs) in combination with platelet-rich plasma (PRP) and recombinant human hepatocyte growth factor (rh-HGF) on a rat model of liver fibrosis/cirrhosis induced by bile duct ligation (BDL). Treatment with PRP or rh-HGF alone did not yield significant hepatoprotection in the BDL-induced liver cirrhosis model. However, ADMSC transplantation alone exhibited the potential to alleviate impaired liver conditions. The combination of PRP and rh-HGF demonstrated superior ameliorative effects compared to either treatment alone. Notably, the combination of ADMSC + PRP or ADMSC + rh-HGF significantly enhanced hepatoprotective capacity compared to individual or combined PRP and rh-HGF therapies. Injection of ADMSC via the tail vein reduced inflammation, hepatocyte damage, and collagen deposition, improving overall liver function. This improvement was more pronounced when ADMSC was administered with PRP and rh-HGF versus monotherapy. Our study concludes that ADMSCs exert antifibrotic effects by inhibiting hepatic stellate cell proliferation, collagen synthesis, and inducing apoptosis. ADMSCs also demonstrate immune-modulatory effects and transdifferentiate into hepatic progenitor cells, secreting trophic factors, cytokines, and chemokines that promote impaired liver regeneration. The observed arrest in liver fibrosis progression highlights the potential therapeutic impact of these interventions.

Evaluation of score parameters for severity assessment of surgery and liver cirrhosis in rats

Severity assessment in animals is an ongoing field of research. In particular, the question of objectifiable and meaningful parameters of score-sheets, as well as their best combination, arise. This retrospective analysis investigates the suitability of a score-sheet for assessing severity and seeks to optimise it for predicting survival in 89 male Sprague Dawley rats (Rattus norvegicus), during an experiment evaluating the influence of liver cirrhosis by bile duct ligation (BDL) on vascular healing. The following five parameters were compared for their predictive power: (i) overall score; (ii) relative weight loss; (iii) general condition score; (iv) spontaneous behaviour score; and (v) the observer's assessment whether pain might be present. Suitable cut-off values of these individual parameters and the combination of multiple parameters were investigated. A total of ten rats (11.2%; 10/89) died or had to be sacrificed at an early stage due to pre-defined humane endpoints. Neither the overall score nor any individual parameter yielded satisfactory results for predicting survival. Using retrospectively calculated cut-off values and combining the overall score with the observer's assessment of whether the animal required analgesia (dipyrone) for pain relief resulted in an improved prediction of survival on the second post-operative day. This study demonstrates that combining score parameters was more suitable than using single ones and that experienced human judgement of animals can be useful in addition to objective parameters in the assessment of severity. By optimising the score-sheet and better understanding the burden of the model on rats, this study contributes to animal welfare.

Quercetin ameliorates acute lung injury in a rat model of hepatopulmonary syndrome

BACKGROUND

Common bile duct ligation (BDL) is a rat experimental model to induce biliary cirrhosis. Lung fibrosis and pulmonary vascular angiogenesis and congestion are the most common complications of biliary cirrhosis that is known as hepatopulmonary syndrome. The aim of the present work is to investigate the acute lung injury in a BDL model and to investigate the possible protective effect of quercetin on this injury.

METHODS

Twenty-four adult male albino rats of the Wister strain (weighing 150-250 g). Animals were divided into 3 groups, with 8 rats each: Group I: Sham-operated group (control). Group II: Bile duct ligation group (BDL) sacrificed after 28 days from the surgery. Group III: Quercetin-treated bile duct ligation group (Q-BDL) was given orally by gastric gavage in a dose of 50 mg/kg/day, starting from the 4th day of the operation until the 28th day. At the end of the experiment, at day 28, all rats were sacrificed. Lung specimens were processed to measure Endothelin B receptor gene expression by PCR, lung surfactant by ELISA, "eNO" s by immunohistochemistry. Histological assessment was done using; H&E, Masson's trichrome, PAS, toluidine blue-stained semi-thin sections, transmission electron microscope. Histomorphometric and statistical studies were done.

RESULTS

BDL group showed significant increase in lung index together with mononuclear cellular infiltration denoting lung inflammatory state. Also, the significant increase in pulmonary endothelial nitric oxide synthase ("eNO" s) area percent and endothelin B receptor (ET_B) gene expression indicates enhanced angiogenesis. Pulmonary surfactant concentration was significantly decreased together with thickening of interalveolar septa denoting lung injury and fibrosis. Quercetin led to significant decrease in lung index, pulmonary "eNO" s area percent, ET_B gene expression and significant increase in pulmonary surfactant concentration. Quercetin treatment improved histological changes and morphometric measurements, limited mononuclear cellular infiltration and decreased perivascular and perialveolar collagen deposition.

CONCLUSION

Quercetin ameliorates the hepatopulmonary syndrome-induced lung injury through its anti-inflammatory, antioxidative and antifibrotic effects.

Silymarin Administration Attenuates Cirrhotic-induced Cardiac Abnormality in the Rats: A Possible Role of β1-adrenergic Receptors and L-type Voltage-Dependent Calcium Channels

Background

Cirrhotic cardiomyopathy is a well-recognized cardiac dysfunction in cirrhotic patients. Studies have confirmed the protective effects of silymarin in different types of cardiac injury. This study aimed to examine the effectiveness and molecular mechanism of silymarin against myocardial dysfunction and hypertrophy in a rat model of cirrhosis.

Methods

The experiment was performed at Alborz University of Medical Sciences (Karaj, Iran) during 2020-2021. Thirty-two male Wistar rats were randomly divided into four groups of Sham-operated (control group for surgical procedures), Bile Duct Ligated (BDL), and two Silymarin extract (SE)-treated groups of 300 and 600 mg/Kg/day. After 28 days, serum levels of AST, ALT, GGT, and ALP, liver histopathological status, as well as cardiac mechanical function, were assessed. Cardiac β₁-adrenergic receptors (β₁-AR), L-type voltage-dependent calcium channels (L-VDCC), and GATA4 mRNA expression were also determined using real-time RT-PCR. Data analysis was performed using the one-way ANOVA followed by Duncan's multiple range test. Histological data has been analyzed with Kruskal-Wallis nonparametric test. The analysis was performed at P≤0.05.

Results

BDL was associated with a significant elevation in serum AST, ALT, GGT, and ALP, development of necrosis and fibrosis of the liver texture, increased Heart Weight and Heart Weight to Body Weight ratio, enhanced cardiac mechanical function as well as a significant up-regulation of ventricular β₁-AR and L-VDCC. Administration of SE600, but not SE300, significantly reduced the serum levels of the enzymes and alleviated signs of liver necrosis and fibrosis. Cirrhotic-induced cardiac dysfunction was also restored by SE600, but not by the lower dose. In addition, cardiac expression of the β₁-AR and L-VDCC was down-regulated toward normal values by either higher or lower doses of the SE.

Conclusion

Silymarin treatment in higher dose attenuated cirrhosis-associated cardiac remodeling and reduced cardiac mechanical dysfunctions.

Evidence of Ventricular Arrhythmogenicity and Cardiac Sympathetic Hyperinnervation in Early Cirrhotic Cardiomyopathy

Cirrhotic cardiomyopathy (CMP) is associated with altered cardiac electrophysiological (EP) properties, which leads to the risk of ventricular arrhythmias (VAs). We aimed to evaluate the EP properties, autonomic, and structural remodeling in a rabbit model with early liver cirrhosis (LC). Twelve rabbits were assigned to the sham and LC groups. The early-stage LC was induced by the ligation of the common bile duct. All rabbits received an EP study, VA inducibility test, myocardial, and liver histology staining. Western blot analyses of protein expression and tyrosine hydroxylase stain for sympathetic nerves were performed. The effective refractory period the LC group was significantly longer than the sham group [i.e., left ventricle (LV) 205.56 ± 40.30 vs. 131.36 ± 7.94 ms; right ventricle (RV) 206.78 ± 33.07 vs. 136.79 ± 15.15 ms; left atrium (LA) 140.56 ± 28.75 vs. 67.71 ± 14.29 ms; and right atrium (RA) 133.78 ± 40.58 vs. 65.43 ± 19.49 ms, all p < 0.01], respectively. The VA inducibility was elevated in the LC group when compared with the sham group (i.e., 21.53 ± 7.71 vs. 7.76 ± 2.44%, p = 0.013). Sympathetic innervation (10²/μm²/mm²) was increased in all cardiac chambers of the LC group compared with the sham group (i.e., LV 9.11 ± 4.86 vs. 0.17 ± 0.15, p < 0.01; RV 4.36 ± 4.95 vs. 0.18 ± 0.12, p = 0.026; LA 6.79 ± 1.02 vs. 0.44 ± 0.20, p = 0.018; and RA 15.18 ± 5.12 vs. 0.10 ± 0.07, p = 0.014), respectively. Early LC is presented with an increased ventricular vulnerability, structural heterogeneity, and sympathetic innervation. Close monitoring for fatal arrhythmias is warranted in patients with early stages of LC.

M2 macrophage accumulation contributes to pulmonary fibrosis, vascular dilatation, and hypoxemia in rat hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) markedly increases the mortality of patients. However, its pathogenesis remains incompletely understood. Rat HPS develops in common bile duct ligation (CBDL)-induced, but not thioacetamide (TAA)-induced cirrhosis. We investigated the mechanisms of HPS by comparing these two models. Pulmonary histology, blood gas exchange, and the related signals regulating macrophage accumulation were assessed in CBDL and TAA rats. Anti-polymorphonuclear leukocyte (antiPMN) and anti-granulocyte-macrophage colony stimulating factor (antiGM-CSF) antibodies, clodronate liposomes (CL), and monocyte chemoattractant protein 1 (MCP1) inhibitor (bindarit) were administrated in CBDL rats, GM-CSF, and MCP1 were administrated in bone marrow-derived macrophages (BMDMs). Pulmonary inflammatory cell recruitment, vascular dilatation, and hypoxemia were progressively developed by 1 week after CBDL, but only occurred at 4 week after TAA. Neutrophils were the primary inflammatory cells within 3 weeks after CBDL and at 4 week after TAA. M2 macrophages were the primary inflammatory cells, meantime, pulmonary fibrosis, GM-CSFR, and CCR2 were specifically increased from 4 week after CBDL. AntiPMN antibody treatment decreased neutrophil and macrophage accumulation, CL or the combination of antiGM-CSF antibody and bindarit treatment decreased macrophage recruitment, resulting in pulmonary fibrosis, vascular dilatation, and hypoxemia in CBDL rats alleviated. The combination treatment of GM-CSF and MCP1 promoted cell migration, M2 macrophage differentiation, and transforming growth factor-β1 (TGF-β1) production in BMDMs. Conclusively, our results highlight neutrophil recruitment mediates pulmonary vascular dilatation and hypoxemia in the early stage of rat HPS. Further, M2 macrophage accumulation induced by GM-CSF/GM-CSFR and MCP1/CCR2 leads to pulmonary fibrosis and promotes vascular dilatation and hypoxemia, as a result, HPS develops.

Bilirubin Induces Pain Desensitization in Cholestasis by Activating 5-Hydroxytryptamine 3A Receptor in Spinal Cord

Background

Cholestasis patients often suffer from pain desensitization, resulting in serious complications in perioperative period. This study was aim to investigate the mechanism of bilirubin in cholestasis mediating pain desensitization through 5-hydroxytryptamine 3A (5-HT_3A ) receptor activation in spinal dorsal horn (SDH).

Methods

A cholestasis model was established by bile duct ligation (BDL) in rats. Pain thresholds of rats were measured after BDL or intrathecally injecting bilirubin in the presence or absence of agonist (mCPBG) and antagonists (ondansetron, bicuculline, or CGP55845). Expression of 5-HT₃ receptors, and the affinity and binding mode of bilirubin to 5-HT_3A receptor were determined. Effects of bilirubin on γ-aminobutyric acid (GABA) pathway and the interactions with 5-HT_3A receptor were tested.

Results

Bilirubin was elevated significantly in both serum and CSF in BDL rats, accompanied with the up-regulation of pain thresholds. Both of 5-HT_3A receptor and GABA _A receptor antagonists could reverse the increased pain threshold in BDL rats. Further, 5-HT_3A and GABA _A receptor expressions were increased in BDL rats or intervention with bilirubin. Molecular docking suggested that bilirubin entered the hydrophobic pocket pre-formed in 5-HT_3A receptor with potential hydrogen bonding. Bilirubin also increased GABA concentrations in CSF and GABAergic spontaneous inhibitory postsynaptic current in spinal cord, and directly induced inward currents in HEK293 cells which were overexpressed 5-HT_3A receptor by lentivirus.

Conclusion

In conclusion, bilirubin induced pain desensitization in cholestasis by activating 5-HT_3A receptor in spinal cord. The activation of 5-HT_3A receptor might regulate pain threshold by acting on the GABA pathway.

Transporter Activity Changes in Nonalcoholic Steatohepatitis: Assessment with Plasma Coproporphyrin I and III

Expression and functional changes in the organic anion transporting polypeptide (OATP)-multidrug resistance-associated protein (MRP) axis of transporters are well reported in patients with nonalcoholic steatohepatitis (NASH). These changes can impact plasma and tissue disposition of endo- and exogenous compounds. The transporter alterations are often assessed by administration of a xenobiotic or by transporter proteomic analysis from liver biopsies. Using gene expression, proteomics, and endogenous biomarkers, we show that the gene expression and activity of OATP and MRP transporters are associated with disease progression and recovery in humans and in preclinical animal models of NASH. Decreased OATP and increased MRP3/4 gene expression in two cohorts of patients with steatosis and NASH, as well as gene and protein expression in multiple NASH rodent models, have been established. Coproporphyrin I and III (CP I and III) were established as substrates of MRP4. CP I plasma concentration increased significantly in four animal models of NASH, indicating the transporter changes. Up to a 60-fold increase in CP I plasma concentration was observed in the mouse bile duct-ligated model compared with sham controls. In the choline-deficient amino acid-defined high-fat diet (CDAHFD) model, CP I plasma concentrations increased by >3-fold compared with chow diet-fed mice. In contrast, CP III plasma concentrations remain unaltered in the CDAHFD model, although they increased in the other three NASH models. These results suggest that tracking CP I plasma concentrations can provide transporter modulation information at a functional level in NASH animal models and in patients. SIGNIFICANCE STATEMENT: Our analysis demonstrates that multidrug resistance-associated protein 4 (MRP4) transporter gene expression tracks with nonalcoholic steatohepatitis (NASH) progression and intervention in patients. Additionally, we show that coproporphyrin I and III (CP I and III) are substrates of MRP4. CP I plasma and liver concentrations increase in different diet- and surgery-induced rodent NASH models, likely explained by both gene- and protein-level changes in transporters. CP I and III are therefore potential plasma-based biomarkers that can track NASH progression in preclinical models and in humans.

CX3CR1 regulates angiogenesis and activation of pro-angiogenic factors and triggers macrophage accumulation in experimental hepatopulmonary syndrome model

OBJECTIVE

Prevalence of hepatopulmonary syndrome (HPS) ranges from 4% to 47% in patients with cirrhosis. This study aimed to explore possible relationship between CX3CR1 and angiogenesis or macrophage accumulation in pathological process of HPS.

MATERIAL AND METHODS

Wide-type C57Bl/6 mice were divided into WT-sham, WT-common bile duct ligation (WT-CBDL), WT-CBDL plus antibody (WT-CBDL+Ab) and WT-CBDL plus Bevacizumab. The CX3CR1^GFP/GFP mice were grouping into CX3CR1 GFP/GFP-sham, CX3CR1 GFP/GFP-CBDL and CX3CR1 GFP/GFP-CBDL+Bevacizumab group. Intrapulmonary expression of Akt, pAkt, ERK, pERK, iNOS, VEGF, PDGF was measured using biological technology. Hematoxylin-eosin (H&E) staining and immunohistochemical analysis were used to evaluate changes of pulmonary tissues including pathological abnormality, angiogenesis and macrophage accumulation.

RESULTS

Blockade CX3CR1 pathway inhibited angiogenesis, macrophage accumulation and pathological changes of lung tissues. Blockade of CX3CR1 pathway reduced pAkt, pERK, iNOS, PDGF and VEGF activation. CX3CR1 contributed to the process of angiogenesis and activate the pro-angiogenic factors. CX3CR1 deficiency obviously reduced the macrophage accumulation. Inhibition of VEGF by Bevacizumab improved intrapulmonary angiogenesis and pathological changes of lung tissues. Inhibition of VEGF by Bevacizumab retarded the production of pAKt, PDGF, and iNOS. Inhibition of VEGF by Bevacizumab reduced CX3CL1 production.

CONCLUSION

CX3CR1 could regulate the angiogenesis and activation of pro-angiogenic factors, including pAKT, pERK, iNOS, VEGF and PDGF in the process of hepato-pulmonary syndrome. Moreover, CX3CR1 could also contribute to the macrophage accumulation.

Recent advances in understanding the molecular mechanisms of cholestatic pruritus: A review

Cholestasis, a condition characterized by an abnormal decrease in bile flow, is accompanied by various symptoms such as pruritus. Although cholestatic pruritus is a prominent condition, its precise mechanisms have largely been elusive. Recently, advancements have been made for understanding the etiology and pathogenesis of cholestatic pruritus. The current review therefore focuses on summarizing the overall progress made in the elucidation of its molecular mechanisms. We have reviewed the available animal models on cholestasis to compare the differences between them, characterized potential pruritogens involved in cholestatic pruritus, and have summarized the receptor and ion channels implicated in the condition. Finally, we have discussed the available treatment options for alleviation of cholestatic pruritus. As our understanding of the mechanisms of cholestatic pruritus deepens, novel strategies to cure this condition are awaited.

Effect of Bile Duct Ligation-induced Liver Dysfunction on Methamphetamine Pharmacokinetics and Locomotor Activity in Rats

PURPOSE

Methamphetamine (METH) abuse is associated with hepatic dysfunction related comorbidities such as HIV, hepatitis C, and polysubstance abuse with acetaminophen-containing opioid formulations. We aimed to develop a bile duct ligation (BDL)-induced hepatic dysfunction model for studying both METH and experimental treatments for METH abuse in this comorbidity.

METHODS

Sham or BDL surgery was performed in male Wistar rats on day 0. Liver function was measured throughout the study. On days 7 and 19, serum pharmacokinetics studies were performed with 1 mg/kg subcutaneous (sc) METH. On day 21, this dose was repeated to determine 2 h post-METH brain concentrations. METH-induced open field behaviors were measured every other day (days 12 - 16) with ascending sc doses (0.3 - 3 mg/kg).

RESULTS

BDL transiently increased alanine aminotransferase levels and altered liver structure, which resulted in significantly greater METH serum and brain exposure. In the BDL compared to sham group, there was a longer duration of METH-induced locomotor activity (after 1 and 3 mg/kg) and stereotypy (after 3 mg/kg).

CONCLUSIONS

In rats, liver dysfunction reduced METH clearance, increased brain METH concentrations, and enhanced METH effects on locomotor activity in a dose dependent manner. In addition, this model could be further developed to simulate the associated hepatic dysfunction of key METH abuse comorbidities for preclinical testing of novel pharmacotherapies for effectiveness and/or toxicity in vulnerable populations.

Hepatocyte-derived exosomal MiR-194 activates PMVECs and promotes angiogenesis in hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a serious vascular complication in the setting of liver disease. Factors produced by the liver are essential to regulate pulmonary angiogenesis in the pathogenesis of HPS; however, the pathogenic mechanisms of pulmonary angiogenesis are not fully understood. We investigated the role of HPS rat serum exosomes (HEs) and sham-operated rat serum exosomes (SEs) in the regulation of angiogenesis. We found that HEs significantly enhance PMVEC proliferation, migration, and tube formation. We further identified miR-194 was the most notably increased miRNA in HEs compared to SEs. Once released, hepatocyte-derived exosomal miR-194 was internalized by PMVECs, leading to the promotion of PMVEC proliferation, migration, and tube formation through direct targeting of THBS1, STAT1, and LIF. Importantly, the pathogenic role of exosomal miR-194 in initiating angiogenesis was reversed by P53 inhibition, exosome secretion inhibition or miR-194 inhibition. Additionally, high levels of miR-194 were found in serum exosomes and were positively correlated with P(A-a)O₂ in HPS patients and rats. Thus, our results highlight that the exosome/miR-194 axis plays a critical pathologic role in pulmonary angiogenesis, representing a new therapeutic target for HPS.

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.

Loss of cell polarity regulated by PTEN/Cdc42 enrolled in the process of Hepatopulmonary Syndrome

One central factor in hepatopulmonary syndrome (HPS) pathogenesis is pulmonary vascular remodelling (PVR) which involves dysregulation of proliferation and migration in pulmonary microvascular endothelial cells (PMVECs). Growing evidence suggests that Apical/basolateral polarity plays an important role in cell proliferation, migration, adhesion and differentiation. In this study, we explored whether cell polarity is involved and critical in experimental HPS rats that are induced by common bile duct ligation (CBDL). Cell polarity related proteins were analysed in CBDL rats lung and PMVECs under the HPS serum stimulation by immunofluorescence assay. Cdc42/PTEN activity, cell proliferation and migration and Annexin A2 (AX2) in PMVECs were determined, respectively. Cell polarity related proteins, lost their specialized luminal localization in PMVECs of the CBDL rat. The loss of cell polarity was induced by abnormal activity of Cdc42, which was strongly enhanced by the interaction between p‐PTEN and Annexin A2 in PMVECs, after treatment with serum from CBDL rats. It led to over‐proliferation and high migration ability of PMVECs. Down‐regulation of PTEN‐Cdc42 activity in PMVECs restored cell polarity and thus reduced their ability of migration and proliferation. Our study suggested that the loss of cell polarity plays a critical role in the pathogenesis of HPS‐associated PVR and may become a potentially effective therapeutic target.

Transplantation of Human Amniotic Membrane over the Liver Surface Reduces Hepatic Fibrosis in a Cholestatic Model in Young Rats

Purpose

Biliary atresia precedes liver cirrhosis and liver transplantation. Amniotic membrane (AM) promotes tissue regeneration, inhibits fibrosis, and reduces inflammation. Here, we test amniotic membrane potential as a therapeutic tool against cholestatic liver fibrosis.

Methods

Three groups of rats were used: sham surgery (SS), bile duct ligature (BDL), and bile duct ligature plus human amniotic membrane (BDL + AM). After surgery, animals were sacrificed at different weeks. Biochemical and histopathological analyses of liver tissue were performed. Collagen was expressed as a percentage of total liver tissue area. qPCR was performed to analyse gene expression levels of transforming growth factor-β1 (Tgfb1) and apelin (Apln). Statistical analysis performed considered p < 0.05 was significant.

Results

Groups undergoing BDL developed cholestasis. Biochemical markers from BDL + AM group improved compared to BDL group. Ductular reaction, portal fibrosis, and bile plugs were markedly reduced in the BDL + AM group compared to BDL group. Collagen area in BDL + AM group was statistically decreased compared to BDL group. Finally, expression levels of both Apln and Tgfb1 mRNA were statistically downregulated in BDL + AM group versus BDL group.

Conclusion

AM significantly reduces liver fibrosis in a surgical animal model of cholestasis. Our results suggest that AM may be useful as a therapeutic tool in liver cirrhosis.

miR144-3p inhibits PMVECs excessive proliferation in angiogenesis of hepatopulmonary syndrome via Tie2

BACKGROUND/AIM

Increasing evidence show microRNAs (miRNAs) are associated with hepatopulmonary syndrome (HPS). The aim of this study was to investigate the role of miR-144 in the angiogenesis of HPS, as well as to identify its underlying mechanism.

METHODS

The expression levels of miR-144-3p were assessed in pulmonary micro-vascular endothelial cells (PMVECs), as well as in lung tissues from rats with HPS. We predicted the potential target of miR-144-3p. Tyrosine kinase 2(Tie2) was identified as a target gene of miR144-3p, which has an essential role in the angiogenesis of lung vessel. In addition, the effects of miR-144-3p regulated on Tie2 was examined. The upregulation and down-regulation of miR-144-3p can affect the proliferation of PMVECs.

RESULTS

We found that the levels of miR-144-3p were frequently downregulated in HPS tissues and cell lines, and overexpression of miR-144-3p dramatically inhibited PMVECs proliferation and cell cycle. We further verified the Tie2 as a novel and direct target of miR-144-3p in HPS.

CONCLUSION

miR-144-3p can negatively regulate PMVECs proliferation by Tie2 expression. In addition, overexpression of miR-144-3p may prove beneficial as a therapeutic strategy for HPS treatment.

AMD3100 treatment attenuates pulmonary angiogenesis by reducing the c-kit (+) cells and its pro-angiogenic activity in CBDL rat lungs

Recent studies have shown that pulmonary angiogenesis is an important pathological process in the development of hepatopulmonary syndrome (HPS), and growing evidence has indicated that Stromal cell-derived factor 1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) axis is involved in pulmonary vascular disease by mediating the accumulation of c-kit+ cells. This study aimed to test the effect of AMD3100, an antagonist of CXCR4, in HPS pulmonary angiogenesis. Common bile duct ligation (CBDL) rats were used as experimental HPS model and were treated with AMD3100 (1.25mg/kg/day, i.p.) or 0.9% saline for 3weeks. The sham rats underwent common bile duct exposure without ligation. The c-kit+ cells accounts and its angiogenic-related functions, prosurvival signals, pulmonary angiogenesis and arterial oxygenation were analysed in these groups. Our results showed that pulmonary SDF-1/CXCR4, Akt, Erk and VEGF/VEGFR2 were significantly activated in CBDL rats, and the numbers of circulating and pulmonary c-kit+ cells were increased in CBDL rats compared with control rats. Additionally, the angiogenic-related functions of c-kit+ cells and pulmonary microvessel counts were also elevated in CBDL rats. CXCR4 inhibition reduced pulmonary c-kit+ cells and microvessel counts and improved arterial oxygenation within 3weeks in CBDL rats. The pulmonary prosurvival signals and pro-angiogenic activity of c-kit+ cells were also down-regulated in AMD3100-treated rats. In conclusion, AMD3100 treatment attenuated pulmonary angiogenesis in CBDL rats and prevented the development of HPS via reductions in pulmonary c-kit+ cells and inhibition of the prosurvival signals. Our study provides new insights in HPS treatment.

3D in vitro models of liver fibrosis

Animal testing is still the most popular preclinical assessment model for liver fibrosis. To develop efficient anti-fibrotic therapies, robust and representative in vitro models are urgently needed. The most widely used in vitro fibrosis model is the culture-induced activation of primary rodent hepatic stellate cells. While these cultures have contributed greatly to the current understanding of hepatic stellate cell activation, they seem to be inadequate to cover the complexity of this regenerative response. This review summarizes recent progress towards the development of 3D culture models of liver fibrosis. Thus far, only a few hepatic culture systems have successfully implemented hepatic stellate cells (or other non-parenchymal cells) into hepatocyte cultures. Recent advances in bioprinting, spheroid- and precision-cut liver slice cultures and the use of microfluidic bioreactors will surely lead to valid 3D in vitro models of liver fibrosis in the near future.

Bile duct ligature in young rats: A revisited animal model for biliary atresia

Biliary atresia leads to cirrhosis in the vast majority of patients and constitutes the first cause of paediatric liver transplantation. Animal models allow us to understand the molecular basis and natural history of diseases. The aim of this study is to describe a surgically created animal model of biliary atresia with emphasis in long-term liver function. Forty-two 3-week-old Sprague-Dawley rats were randomly divided into two groups: bile duct ligature (BDL) and control. The animals were sacrificed on the 2nd, 4th, and 6th postoperative weeks. Blood samples were collected for liver function analysis. The spleen to body weight ratio was determined. Histopathological examination of liver tissue was performed by hematoxylin-eosin and Sirius red staining. Collagen quantification was determined by using colorimetric digital image analysis and was expressed as a percentage of total liver tissue area. Quantitative real-time polymerase chain reaction was performed to analyse gene expression levels of transforming growth factor-β1 (Tgfb1) and apeline (Apln) genes. Statistical analysis was performed where P&lt;0.05 was considered significant. Animals from BDL group developed increasing cholestasis with clinical and laboratory features. Splenomegaly was detected at 4th and 6th week (P&lt;0.05). Histological evaluation of the liver showed ductular reaction, portal fibrosis and bile plugs. Collagen area to total liver tissue area had a median of 2.5% in the control group and 6.5 %, 14.3 % and 37.7 % in BDL rats at 2nd, 4th and 6th weeks respectively (P&lt;0.001). Tgfb1 mRNA expression level was significantly higher at 6th week (P&lt;0.001) in BDL group when compared to control. Apln mRNA expression level was significantly higher at 4th and 6th week (P&lt;0.001) and showed a positive linear correlation (r = 0.975, P&lt;0.05) in BDL group when compared to control. Bile duct ligature in young rats is an animal model that recreates clinical, laboratory, histological and molecular findings of biliary atresia. Bile duct ligature constitutes a good animal model to investigate therapeutic approaches for modifying the progression of liver fibrosis in biliary atresia.

The ET-1-mediated carbonylation and degradation of ANXA1 induce inflammatory phenotype and proliferation of pulmonary artery smooth muscle cells in HPS

Hepatopulmonary syndrome (HPS) is a serious complication of advanced liver disease, which markedly increases mortality. Pulmonary vascular remodelling (PVR) induced by circulating mediators plays an important role in the pathogenesis of HPS, while the underlying mechanism remains undefined. In the present study, we reported that endothelin-1 (ET-1) is up-regulated and annexin A1(ANXA1) is down-regulated in HPS rat, and ET-1 decreases the ANXA1 expression in a dose-dependent manner in rat pulmonary arterial smooth muscle cells (PASMCs). Then, we showed that ANXA1 can decrease nuclear p-ERK1/2 accumulation and decrease the cyclin D1 expression, thus resulting in the subsequent inhibition of PASMCs proliferation. As previously reported, we confirmed that ET-1 decreases the ANXA1 protein levels by the carbonylation and degradation of ANXA1. In conclusion, our research links the signaling cascade of ET1-ANXA1-cell proliferation to a potential therapeutic strategy for blocking IPS-associated PVR.

Inhibition of autophagy ameliorates pulmonary microvascular dilation and PMVECs excessive proliferation in rat experimental hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a defective liver-induced pulmonary vascular disorder with massive pulmonary microvascular dilation and excessive proliferation of pulmonary microvascular endothelial cells (PMVECs). Growing evidence suggests that autophagy is involved in pulmonary diseases, protectively or detrimentally. Thus, it is interesting and important to explore whether autophagy might be involved in and critical in HPS. In the present study, we report that autophagy was activated in common bile duct ligation (CBDL) rats and cultured pulmonary PMVECs induced by CBDL rat serum, two accepted in vivo and in vitro experimental models of HPS. Furthermore, pharmacological inhibition of autophagy with 3-methyladenine (3-MA) significantly alleviated pathological alterations and typical symptom of HPS in CBDL rats in vivo, and consistently 3-MA significantly attenuated the CBDL rat serum-induced excessive proliferation of PMVECs in vitro. All these changes mediated by 3-MA might explain the observed prominent improvement of pulmonary appearance, edema, microvascular dilatation and arterial oxygenation in vivo. Collectively, these results suggest that autophagy activation may play a critical role in the pathogenesis of HPS, and autophagy inhibition may have a therapeutic potential for this disease.

The angiogenic related functions of bone marrow mesenchymal stem cells are promoted by CBDL rat serum via the Akt/Nrf2 pathway

Hepatopulmonary syndrome (HPS) is a complication of severe liver disease. It is characterized by an arterial oxygenation defect. Recent studies have demonstrated that pulmonary angiogenesis contributes to the abnormal gas exchange found in HPS. Additionally, mesenchymal stem cells (MSCs) are considered the stable source of VEGF-producing cells and have the potential to differentiate into multiple cell types. However, it has not been determined whether bone marrow mesenchymal stem cells (BM-MSCs) are mobilized and involved in the pulmonary angiogenesis in HPS. In this study, a CFU-F assay showed that the number of peripheral blood MSCs was increased in common bile duct ligation (CBDL) rats; however, there was no significant difference found in the number of BM-MSCs. In vitro, CBDL rat serum induced the overexpression of CXCR4 and PCNA in BM-MSCs. Consistently, the directional migration as well as the proliferation ability of BM-MSCs were enhanced by CBDL rat serum, as determined by a transwell migration and MTT assays. Moreover, the secretion of VEGF by BM-MSCs increased after treatment with CBDL rat serum. We also found that the expression of phospho-Akt, phospho-ERK, and Nrf2 in BM-MSCs was significantly up-regulated by CBDL rat serum in a time dependent manner, and the blockage of the Akt/Nrf2 signalling pathway with an Akt Inhibitor or Nrf2 siRNA, instead of an ERK inhibitor, attenuated the migration, proliferation and paracrine capacity of BM-MSCs. In conclusion, these findings indicated that the number of MSCs increased in the peripheral blood of CBDL rats, and the Akt/Nrf2 pathway plays a vital role in promoting the angiogenic related functions of BM-MSCs, which could be a potent contributor to pulmonary angiogenesis in HPS.

Dexmedetomidine Attenuates Bilirubin-Induced Lung Alveolar Epithelial Cell Death In Vitro and In Vivo

Objective:

To investigate bilirubin-induced lung alveolar epithelial cell injury together with the protection afforded by dexmedetomidine.

Design:

Prospective, randomized, controlled study.

Setting:

Research laboratory.

Subjects:

Sprague Dawley rats.

Interventions:

Alveolar epithelial A549 cell lines were cultured and received bilirubin (from 0 to 160 μM) to explore the protective pathway of dexmedetomidine on bilirubin-induced alveolar epithelial cell injury assessed by immunochemistry and flow cytometry. Sprague-Dawley rats were subjected to common bile duct ligation surgery to explore the protective effect of dexmedetomidine on hyperbilirubinemia-induced alveolar epithelial cell injury and respiratory failure in comparison with the Sham (subjected to the surgery procedure but without bile duct ligation) or dexmedetomidine control (only received intraperitoneal injection of dexmedetomidine).

Measurements and Main Results:

In vitro, dexmedetomidine reversed the collapse of mitochondrial membrane potential (Δψm), upregulation of cytochrome C, B cell leukemia 2 associated X protein, and cleaved-caspase 3 and 9 in A549 epithelial cells with bilirubin challenge. Furthermore, dexmedetomidine reversed the arrest of cell cycle and the downregulation of the transforming growth factorβ, phosphorylated mammalian target of rapamycin, and p42/44 mitogen-activated protein kinase induced by bilirubin. In vivo, pulmonary edema and inflammation were found after common bile duct ligation. Bilirubin and Paco₂ were significantly increased, and oxygen (Pao₂) was significantly decreased in the blood of common bile duct ligation rats from the postsurgery day 7 to day 21 when compared with those in the sham controls, respectively (p < 0.01). Daily intraperitoneal injection of dexmedetomidine significantly alleviated the lung edema and injury and prevented respiratory failure.

Conclusion:

Our data both in vitro and in vivo demonstrated that dexmedetomidine protected alveolar epithelial cell from bilirubin-induced injury. Dexmedetomidine may be a good choice of anesthetic/sedative for patients with chronic liver disease during the perioperative period.

Mechanical characteristics of the pulmonary artery in beagle dogs with hepatopulmonary syndrome and portopulmonary hypertension

The continuous changes in pulmonary hemodynamic properties in hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PoPH) have not been fully characterized in large animal models of HPS and PoPH. Beagle dog models of HPS and PoPH were induced by chronic common bile duct ligation and Sephadex microspheres, respectively. The model was validated by catheter examination and pathological analyses, and the hemodynamic characteristics of the models were observed. The results revealed that the cross-sectional area of the blood vessel was significantly increased in HPS models, but it was significantly decreased in the PoPH models. Furthermore, the resistance of pulmonary circulation was elevated in models of HPS, but it was decreased in models of PoPH. The present findings renew the traditional view that pulmonary hypertension is due to the enhanced peripheral resistance.

Bone morphogenic protein-2 regulates the myogenic differentiation of PMVECs in CBDL rat serum-induced pulmonary microvascular remodeling

Hepatopulmonary syndrome (HPS) is characterized by an arterial oxygenation defect induced by intrapulmonary vasodilation (IPVD) that increases morbidity and mortality. In our previous study, it was determined that both the proliferation and the myogenic differentiation of pulmonary microvascular endothelial cells (PMVECs) play a key role in the development of IPVD. However, the molecular mechanism underlying the relationship between IPVD and the myogenic differentiation of PMVECs remains unknown. Additionally, it has been shown that bone morphogenic protein-2 (BMP2), via the control of protein expression, may regulate cell differentiation including cardiomyocyte differentiation, neuronal differentiation and odontoblastic differentiation. In this study, we observed that common bile duct ligation (CBDL)-rat serum induced the upregulation of the expression of several myogenic proteins (SM-α-actin, calponin, SM-MHC) and enhanced the expression levels of BMP2 mRNA and protein in PMVECs. We also observed that both the expression levels of Smad1/5 and the activation of phosphorylated Smad1/5 were significantly elevated in PMVECs following exposure to CBDL-rat serum, which was accompanied by the down-regulation of Smurf1. The blockage of the BMP2/Smad signaling pathway with Noggin inhibited the myogenic differentiation of PMVECs, a process that was associated with relatively low expression levels of both SM-α-actin and calponin in the setting of CBDL-rat serum exposure, although SM-MHC expression was not affected. These findings suggested that the BMP2/Smad signaling pathway is involved in the myogenic differentiation of the PMVECs. In conclusion, our data highlight the pivotal role of BMP2 in the CBDL-rat serum-induced myogenic differentiation of PMVECs via the activation of both Smad1 and Smad5 and the down-regulation of Smurf1, which may represent a potential therapy for HPS-induced pulmonary vascular remodeling.