Defective endothelial nitric oxide synthase signaling is mediated by rho-kinase activation in rats with secondary biliary cirrhosis

Potent Efficacy of 3-Amino-4-hydroxy Benzoic Acid, a Small Molecule Having Anti-fibrotic Activity, in a Mouse Model of Non-alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH), which is on the rise due to the increasing obese population and changing lifestyles, causes fibrosis over time and carries the risk of progression to cirrhosis and hepatocellular carcinoma. However, there are no approved effective treatments for NASH. Recent studies suggest that increased lipid metabolism and reduced nitric oxide content are responsible for NASH; 3-amino-4-hydroxy benzoic acid (AHBA) was identified as an inhibitor for the phosphatase activity of soluble epoxy hydrolase, which in turn inhibits lipid metabolism and endothelial nitric oxide synthase activity. The aim of this study was to assess the efficacy of AHBA in a mouse model of NASH. NASH was induced in mice by streptozotocin administration and a high-fat diet loading. The efficacy of AHBA was determined by measuring liver function using serum and liver samples and conducting a morphological assessment. AHBA considerably attenuated the increase in the liver weight and alkaline phosphatase content, which occurred due to the progression of NASH. Hepatocellular steatosis, inflammatory cell infiltration, and hepatocellular ballooning of hepatocytes remained unaltered. In contrast, AHBA treatment significantly ameliorated the fibrotic alterations within liver tissue that were induced by the onset of NASH. These results demonstrate the potential of AHBA as a therapeutic pharmaceutical compound that can treat NASH.

Outcomes of Patients with Child-Pugh B and Unresectable Hepatocellular Carcinoma Undergoing First-Line Systemic Treatment with Sorafenib, Lenvatinib, or Atezolizumab Plus Bevacizumab

INTRODUCTION

Systemic therapy is recommended for patients with Child-Pugh A in hepatocellular carcinoma (HCC). We analyzed the outcomes of a cohort of patients with HCC who received either sorafenib (Sor), lenvatinib (Len) or atezolizumab plus bevacizumab (Atezo + Bev) as first-line systemic therapy for HCC, with the aim of identifying prognostic factors for survival.

METHODS

A total of 825 patients with advanced HCC and Child-Pugh A or B received either Sor, Len or Atezo + Bev as first-line systemic therapy. Liver function was assessed according to the Child-Pugh score and the modified albumin-bilirubin (mALBI) grade.

RESULTS

Prognosis was analyzed according to liver function such as Child-Pugh classifications, scores, and mALBI grades that worsened with a decline in liver function (p <0.001 for all). A Child-Pugh score of 7 was a factor significantly associated with OS. In patients with a Child-Pugh score of 7, an mALBI grade of 3 was an independent predictor of OS. In Child-Pugh B patients with HCC, receiving Atezo + Bev was identified as a factor associated with PFS.

CONCLUSION

Determining the hepatic reserve of patients with unresectable HCC might be useful for identifying patents suitable for systemic treatment for HCC. Atezo + Bev might prolong the PFS of patients with a Child-Pugh score of 7.

Modulating T Cell Phenotype and Function to Treat Hypertension

Hypertension is the leading modifiable risk factor of worldwide morbidity and mortality because of its effects on cardiovascular and renal end-organ damage. Unfortunately, BP control is not sufficient to fully reduce the risks of hypertension, underscoring the need for novel therapies that address end-organ damage in hypertension. Over the past several decades, the link between immune activation and hypertension has been well established, but there are still no therapies for hypertension that specifically target the immune system. In this review, we describe the critical role played by T cells in hypertension and hypertensive end-organ damage and outline potential therapeutic targets to modulate T-cell phenotype and function in hypertension without causing global immunosuppression.

Rho-kinase inhibition ameliorates non-alcoholic fatty liver disease in type 2 diabetic rats

Non-alcoholic fatty liver disease (NAFLD) is linked to type 2 diabetes mellitus (T2DM), obesity, and insulin resistance. The Rho/ROCK pathway had been involved in the pathophysiology of diabetic complications. This study was designed to assess the possible protective impacts of the Rho/Rho-associated coiled-coil containing protein kinase (Rho/ROCK) inhibitor fasudil against NAFLD in T2DM rats trying to elucidate the underlying mechanisms. Animals were assigned into control rats, non-treated diabetic rats with NAFLD, and diabetic rats with NAFLD that received fasudil treatment (10 mg/kg per day) for 6 weeks. The anthropometric measures and biochemical analyses were performed to assess metabolic and liver function changes. The inflammatory and oxidative stress markers and the histopathology of rat liver tissues were also investigated. Groups with T2DM showed increased body weight, serum glucose, and insulin resistance. They exhibited disturbed lipid profile, enhancement of inflammatory cytokines, and deterioration of liver function. Fasudil administration reduced body weight, insulin resistance, and raised liver enzymes. It improved the disturbed lipid profile and attenuated liver inflammation. Moreover, it slowed down the progression of high fat diet (HFD)-induced liver injury and reduced the caspase-3 expression. The present study demonstrated beneficial amelioration effect of fasudil on NAFLD in T2DM. The mechanisms underlying these impacts are improving dyslipidemia, attenuating oxidative stress, downregulated inflammation, improving mitochondrial architecture, and inhibiting apoptosis.

Intercellular crosstalk of liver sinusoidal endothelial cells in liver fibrosis, cirrhosis and hepatocellular carcinoma

Intercellular crosstalk among various liver cells plays an important role in liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Capillarization of liver sinusoidal endothelial cells (LSECs) precedes fibrosis and accumulating evidence suggests that the crosstalk between LSECs and other liver cells is critical in the development and progression of liver fibrosis. LSECs dysfunction, a key event in the progression from fibrosis to cirrhosis, and subsequently obstruction of hepatic sinuses and increased intrahepatic vascular resistance (IHVR) contribute to development of portal hypertension (PHT) and cirrhosis. More importantly, immunosuppressive tumor microenvironment (TME), which is closely related to the crosstalk between LSECs and immune liver cells like CD8+ T cells, promotes advances tumorigenesis, especially HCC. However, the connections within the crosstalk between LSECs and other liver cells during the progression from liver fibrosis to cirrhosis to HCC have yet to be discussed. In this review, we first summarize the current knowledge of how different crosstalk between LSECs and other liver cells, including hepatocytes, hepatic stellate cells (HSCs), macrophoges, immune cells in liver and extra cellular matrix (ECM) contribute to the physiological function and the progrssion from liver fibrosis to cirrhosis, or even to HCC. Then we examine current treatment strategies for LSECs crosstalk in liver fibrosis, cirrhosis and HCC.

Strategies Targeting the Innate Immune Response for the Treatment of Hepatitis C Virus-Associated Liver Fibrosis

Direct-acting antivirals eliminate hepatitis C virus (HCV) in more than 95% of treated individuals and may abolish liver injury, arrest fibrogenesis, and reverse fibrosis and cirrhosis. However, liver regeneration is usually a slow process that is less effective in the late stages of fibrosis. What is more, fibrogenesis may prevail in patients with advanced cirrhosis, where it can progress to liver failure and hepatocellular carcinoma. Therefore, the development of antifibrotic drugs that halt and reverse fibrosis progression is urgently needed. Fibrosis occurs due to the repair process of damaged hepatic tissue, which eventually leads to scarring. The innate immune response against HCV is essential in the initiation and progression of liver fibrosis. HCV-infected hepatocytes and liver macrophages secrete proinflammatory cytokines and chemokines that promote the activation and differentiation of hepatic stellate cells (HSCs) to myofibroblasts that produce extracellular matrix (ECM) components. Prolonged ECM production by myofibroblasts due to chronic inflammation is essential to the development of fibrosis. While no antifibrotic therapy is approved to date, several drugs are being tested in phase 2 and phase 3 trials with promising results. This review discusses current state-of-the-art knowledge on treatments targeting the innate immune system to revert chronic hepatitis C-associated liver fibrosis. Agents that cause liver damage may vary (alcohol, virus infection, etc.), but fibrosis progression shows common patterns among them, including chronic inflammation and immune dysregulation, hepatocyte injury, HSC activation, and excessive ECM deposition. Therefore, mechanisms underlying these processes are promising targets for general antifibrotic therapies.

Prognostic values of immune scores and immune microenvironment-related genes for hepatocellular carcinoma

It is crucial to grasp the characteristics of tumour immune microenvironment to improve effects of immunotherapy. In this study, the immune and stromal scores of 371 cases were calculated for quantitative analysis of immune and stromal cell infiltration in the tumour microenvironment of hepatocellular carcinoma (HCC). The weighted gene co-expression network analysis and protein–protein interaction network were analysed to identify immune microenvironment-related genes. The results showed that patients with high immune scores had a higher 4-year recurrence-free rate. TP53, CTNNB1, and AXIN1 mutations significantly varied with immune scores. In immune score-related modules analysis, Kyoto encyclopaedia of genes and genomes pathways and gene ontology terms were closely related to immune processes, tumorigenesis, and metastasis. Twelve new immune microenvironment-related genes were identified and had significantly positive correlations with seven immune checkpoint genes. In prognostic analysis, eleven immune microenvironment-related genes exhibited high expression, nine of which were validated in the GSE62232 dataset and were significantly associated with a good prognosis. Our findings suggest that calculating immune score and stromal score could help to determine tumour purity and immune cell infiltration in the tumour microenvironment. Nine immune microenvironment-related genes identified in this study had potential as prognostic markers for HCC.

Tissue-Specific Approaches Reveal Diverse Metabolic Functions of Rho-Kinase 1

Rho-kinase 1 (ROCK1) has been implicated in diverse metabolic functions throughout the body, with promising evidence identifying ROCK1 as a therapeutic target in diabetes and obesity. Considering these metabolic roles, several pharmacological inhibitors have been developed to elucidate the mechanisms underlying ROCK1 function. Y27632 and fasudil are two common ROCK1 inhibitors; however, they have varying non-specific selectivity to inhibit other AGC kinase subfamily members and whole-body pharmacological approaches lack tissue-specific insight. As a result, interpretation of studies with these inhibitors is difficult, and alternative approaches are needed to elucidate ROCK1's tissue specific metabolic functions. Fortunately, recent technological advances utilizing molecular carriers or genetic manipulation have facilitated discovery of ROCK1's tissue-specific mechanisms of action. In this article, we review the tissue-specific roles of ROCK1 in the regulation of energy balance and substrate utilization. We highlight prominent metabolic roles in liver, adipose, and skeletal muscle, in which ROCK1 regulates energy expenditure, glucose uptake, and lipid metabolism via inhibition of AMPK2α and paradoxical modulation of insulin signaling. Compared to ROCK1's roles in peripheral tissues, we also describe contradictory functions of ROCK1 in the hypothalamus to increase energy expenditure and decrease food intake via leptin signaling. Furthermore, dysregulated ROCK1 activity in either of these tissues results in metabolic disease phenotypes. Overall, tissue-specific approaches have made great strides in deciphering the many critical metabolic functions of ROCK1 and, ultimately, may facilitate the development of novel treatments for metabolic disorders.

Early changes in ammonia levels and liver function in patients with advanced hepatocellular carcinoma treated by lenvatinib therapy

We aimed to investigate the early changes in ammonia levels and liver function in patients with advanced hepatocellular carcinoma treated with lenvatinib. This retrospective study included 23 patients with advanced hepatocellular carcinoma who were able to receive lenvatinib continuously for at least 1 week. We compared their ammonia levels (NH3), total bilirubin (Bil), albumin, and prothrombin (PT) activity at before and after 1 week of lenvatinib administration, and additionally, compared the 2 groups which were divided based on the presence/absence of portosystemic collaterals (PSCs). Before administration of lenvatinib the patients with PSCs had significantly worse ammonia levels and liver function than the patients without PSCs (NH₃: P = 0.013, Bil: P = 0.004, PT: P = 0.047, respectively). Moreover, the indices were worse in all the patients after 1 week of lenvatinib than before administration (NH3: P = 0.001, Bil: P = 0.025, PT: P < 0.001, respectively). Moreover, the changes in ammonia levels were investigated for 4 weeks. The ammonia level increased, to peak at 2 weeks, but decreased after 3 weeks. None of the patients discontinued lenvatinib therapy because of an adverse event. The ammonia levels of the study patients increased from baseline at 1 week after lenvatinib administration, but therapy could be continued for 4 weeks by appropriate management.

Hepatic microcirculation and mechanisms of portal hypertension

The liver microcirculatory milieu, mainly composed of liver sinusoidal endothelial cells (LSECs), hepatic stellate cells (HSCs) and hepatic macrophages, has an essential role in liver homeostasis, including in preserving hepatocyte function, regulating the vascular tone and controlling inflammation. Liver microcirculatory dysfunction is one of the key mechanisms that promotes the progression of chronic liver disease (also termed cirrhosis) and the development of its major clinical complication, portal hypertension. In the present Review, we describe the current knowledge of liver microcirculatory dysfunction in cirrhotic portal hypertension and appraise the preclinical models used to study the liver circulation. We also provide a comprehensive summary of the promising therapeutic options to target the liver microvasculature in cirrhosis.

Percutaneous transvenous shunt occlusion for portosystemic encephalopathy due to lenvatinib administration to a patient with hepatocellular carcinoma and portosystemic shunt

We report a 74-year-old male patient with compensated cirrhosis after hepatic C virus eradication. After the patient underwent hepatectomy for hepatocellular carcinoma, multiple lung and lymph node metastases were detected by computed tomography. Computed tomography also revealed a portosystemic shunt from the superior mesenteric vein to the right testicular vein. He was administered lenvatinib (12 mg). Five days after the initiation of lenvatinib, he developed grade 3 hepatic encephalopathy, and his ammonia level increased. Lenvatinib was stopped, with improvement of the encephalopathy and decrease in ammonia level. When lenvatinib was restarted, grade 2 encephalopathy recurred which then improved upon stopping the drug. We thought that the encephalopathy was due to the portosystemic shunt, and occlusion of the shunt was performed. The day after shunt occlusion, lenvatinib (8 mg) was restarted, and the lenvatinib dose was increased to 12 mg at 2 days after shunt occlusion. Subsequently, the ammonia level remained stable and the patient remained alert and conscious. Lenvatinib was continued until the time of this report (40 days after shunt occlusion), and after 1 month of lenvatinib therapy, the computed tomography verified absence of the portosystemic shunt and stable disease of hepatocellular carcinoma.

Research progress on signaling pathways in cirrhotic portal hypertension

Portal hypertension (PHT) is an important consequence of liver cirrhosis, which can lead to complications that adversely affect a patient’s quality of life and survival, such as upper gastrointestinal bleeding, ascites, and portosystemic encephalopathy. In recent years, advances in molecular biology have led to major discoveries in the pathological processes of PHT, including the signaling pathways that may be involved: PI3K-AKT-mTOR, RhoA/Rho-kinase, JAK2/STAT3, and farnesoid X receptor. However, the pathogenesis of PHT is complex and there are numerous pathways involved. Therefore, the targeting of signaling pathways for medical management is lagging. This article summarizes the progress that has been made in understanding the signaling pathways in PHT, and provides ideas for treatment of the disorder.

Transcriptomic Analysis of Hepatic Cells in Multicellular Organotypic Liver Models

Liver homeostasis requires the presence of both parenchymal and non-parenchymal cells (NPCs). However, systems biology studies of the liver have primarily focused on hepatocytes. Using an organotypic three-dimensional (3D) hepatic culture, we report the first transcriptomic study of liver sinusoidal endothelial cells (LSECs) and Kupffer cells (KCs) cultured with hepatocytes. Through computational pathway and interaction network analyses, we demonstrate that hepatocytes, LSECs and KCs have distinct expression profiles and functional characteristics. Our results show that LSECs in the presence of KCs exhibit decreased expression of focal adhesion kinase (FAK) signaling, a pathway linked to LSEC dedifferentiation. We report the novel result that peroxisome proliferator-activated receptor alpha (PPARα) is transcribed in LSECs. The expression of downstream processes corroborates active PPARα signaling in LSECs. We uncover transcriptional evidence in LSECs for a feedback mechanism between PPARα and farnesoid X-activated receptor (FXR) that maintains bile acid homeostasis; previously, this feedback was known occur only in HepG2 cells. We demonstrate that KCs in 3D liver models display expression patterns consistent with an anti-inflammatory phenotype when compared to monocultures. These results highlight the distinct roles of LSECs and KCs in maintaining liver function and emphasize the need for additional mechanistic studies of NPCs in addition to hepatocytes in liver-mimetic microenvironments.

Reactive oxygen species-responsive polymeric nanoparticles for alleviating sepsis-induced acute liver injury in mice

Sepsis-associated acute liver injury contributes to the pathogenesis of multiple organ dysfunction syndrome and is associated with increased mortality. Currently, no specific therapeutics for sepsis-associated liver injury are available. With excess levels of reactive oxygen species (ROS) being implicated as key players in sepsis-induced liver injury, we hypothesize that ROS-responsive nanoparticles (NPs) formed via the self-assembly of diblock copolymers of poly(ethylene glycol) (PEG) and poly(propylene sulfide) (PPS) may function as an effective drug delivery system for alleviating sepsis-induced liver injury by preferentially releasing drug molecules at the disease site. However, there are no reports available on the biocompatibility and effect of PEG-b-PPS-NPs in vivo. Herein, this platform was tested for delivering the promising antioxidant therapeutic molecule melatonin (Mel), which currently has limited therapeutic efficacy because of its poor pharmacokinetic properties. The mPEG-b-PPS-NPs efficiently encapsulated Mel using the oil-in-water emulsion technique and provided sustained, on-demand release that was modulated in vitro by the hydrogen peroxide concentration. Animal studies using a mouse model of sepsis-induced acute liver injury revealed that Mel-loaded mPEG-b-PPS-NPs are biocompatible and much more efficacious than an equivalent amount of free drug in attenuating oxidative stress, the inflammatory response, and subsequent liver injury. Accordingly, this work indicates that mPEG-b-PPS-NPs show potential as an ROS-mediated on-demand drug delivery system for improving Mel bioavailability and treating oxidative stress-associated diseases such as sepsis-induced acute liver injury.

Role of estrogen receptor β selective agonist in ameliorating portal hypertension in rats with CCl4-induced liver cirrhosis

AIM: To investigate the role of diarylpropionitrile (DPN), a selective agonist of estrogen receptor β (ERβ), in liver cirrhosis with portal hypertension (PHT) and isolated hepatic stellate cells (HSCs).

METHODS: Female Sprague-Dawley rats were ovariectomized (OVX), and liver cirrhosis with PHT was induced by CCl₄ injection. DPN and PHTPP, the selective ERβ agonist and antagonist, were used as drug interventions. Liver fibrosis was assessed by hematoxylin and eosin (HE) and Masson’s trichrome staining and by analyzing smooth muscle actin expression. Hemodynamic parameters were determined in vivo using colored microspheres technique. Protein expression and phosphorylation were determined by immunohistochemical staining and Western blot analysis. Messenger RNA levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Collagen gel contraction assay was performed using gel lattices containing HSCs treated with DPN, PHTPP, or Y-27632 prior to ET-1 addition.

RESULTS: Treatment with DPN in vivo greatly lowered portal pressure and improved hemodynamic parameters without affecting mean arterial pressure, which was associated with the attenuation of liver fibrosis and intrahepatic vascular resistance (IHVR). In CCl₄-treated rat livers, DPN significantly decreased the expression of RhoA and ROCK II, and even suppressed ROCK II activity. Moreover, DPN remarkedly increased the levels of endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS, and promoted the activities of protein kinase G (PKG), which is an NO effector in the liver. Furthermore, DPN reduced the contractility of activated HSCs in the 3-dimensional stress-relaxed collagen lattices, and decreased the ROCK II activity in activated HSCs. Finally, in vivo/in vitro experiments demonstrated that MLC activity was inhibited by DPN.

CONCLUSION: For OVX rats with liver cirrhosis, DPN suppressed liver RhoA/ROCK signal, facilitated NO/PKG pathways, and decreased IHVR, giving rise to reduced portal pressure. Therefore, DPN represents a relevant treatment choice against PHT in cirrhotic patients, especially postmenopausal women.

Molecular pathophysiology of portal hypertension

Over the past two decades the advances in molecular cell biology have led to significant discoveries about the pathophysiology of portal hypertension (PHT). In particular, great progress has been made in the study of the molecular and cellular mechanisms that regulate the increased intrahepatic vascular resistance (IHVR) in cirrhosis. We now know that the increased IHVR is not irreversible, but that both the structural component caused by fibrosis and the active component caused by hepatic sinusoidal constriction can be, at least partially, reversed. Indeed, it is now apparent that the activation of perisinusoidal hepatic stellate cells, which is a key event mediating the augmented IHVR, is regulated by multiple signal transduction pathways that could be potential therapeutic targets for PHT treatment. Furthermore, the complexity of the molecular physiology of PHT can also be appreciated when one considers the complex signals capable of inducing vasodilatation and hyporesponsiveness to vasoconstrictors in the splanchnic vascular bed, with several vasoactive molecules, controlled at multiple levels, working together to mediate these circulatory abnormalities. Added to the complexity is the occurrence of pathological angiogenesis during the course of disease progression, with recent emphasis given to understanding its molecular machinery and regulation. Although much remains to be learned, with the current availability of reagents and new technologies and the exchange of concepts and data among investigators, our knowledge of the molecular basis of PHT will doubtless continue to grow, accelerating the transfer of knowledge generated by basic research to clinical practice. This will hopefully permit a better future for patients with PHT.

Pathophysiology of Portal Hypertension

The bases of our current knowledge on the physiology of the hepatic portal system are largely owed to the work of three pioneering vascular researchers from the sixteenth and the seventeenth centuries: A. Vesalius, W. Harvey, and F. Glisson. Vesalius is referred to as the founder of modern human anatomy, and in his influential book, De humani corporis fabrica libri septem, he elaborated the first anatomical atlas of the hepatic portal venous system (Vesalius 2013). Sir William Harvey laid the foundations of modern cardiovascular research with his Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (Harvey 1931) in which he established the nature of blood circulation. Finally, F. Glisson characterized the gastrointestinal-hepatic vascular system (Child 1955). These physiological descriptions were later complemented with clinical observations. In the eighteenth and nineteenth centuries, Morgagni, Puckelt, Cruveilhier, and Osler were the first to make the connection between common hepatic complications – ascites, splenomegaly, and gastrointestinal bleeding – and obstruction of the portal system (Sandblom 1993). These were the foundations that allowed Gilbert, Villaret, and Thompson to establish an early definition of portal hypertension at the beginning of the twentieth century. In this period, Thompson performed the first direct measurement of portal pressure by laparotomy in some patients (Gilbert and Villaret 1906; Thompson et al. 1937). Considering all these milestones, and paraphrasing Sir Isaac Newton, if hepatologists have seen further, it is by standing on the shoulders of giants.

Nowadays, our understanding of the pathogenesis of portal hypertension has largely improved thanks to the progress in preclinical and clinical research. However, this field is ever-changing and hepatologists are continually identifying novel pathological mechanisms and developing new therapeutic strategies for this clinical condition. Hence, the aim of this chapter is to summarize the current knowledge about this clinical condition.

Rho-kinase inhibitor targeting the liver prevents ischemia/reperfusion injury in the steatotic liver without major systemic adversity in rats

Rho-kinase (ROCK) inhibitors improve liver blood flow after ischemia/reperfusion (IR) injury, especially in the setting of steatosis, by decreasing the resistance of intrahepatic microcirculation through hepatic stellate cell (HSC) relaxation. However, the systemic administration of ROCK inhibitors causes severe hypotension; therefore, liver-specific ROCK inhibition is required. Here, we tested vitamin A (VA)-coupled liposomes carrying the ROCK inhibitor Y-27632 for targeted HSCs in steatotic rats. Rat livers with steatosis induced by a choline-deficient diet were subjected to IR injury. The delivery site and effect of the ROCK inhibitor were investigated. After liposomal Y-27632 injection, the survival rate after IR, the liver blood flow, the portal perfused pressure, and the hemodynamics were investigated. Immunohistochemical studies showed VA-coupled liposome accumulation in livers. Liposomal Y-27632 was 100-fold more effective in inhibiting HSC activation than free Y-27632. Liposomal Y-27632 improved the survival rate after IR injury, the liver blood flow, and the portal perfusion pressure without severe hypotension. In contrast, untargeted Y-27632 elicited severe systemic hypotension. We conclude that VA-coupled liposomes carrying the ROCK inhibitor yield enhanced drug accumulation in the liver and thus mitigate IR injury in the steatotic liver and reduce major systemic adversity.

Sodium ferulate lowers portal pressure in rats with secondary biliary cirrhosis through the RhoA/Rho-kinase signaling pathway: a preliminary study

Cirrhotic rats show higher expression levels of hepatic RhoA and Rho-kinase than normal healthy rats, and the activation of this signaling pathway leads to portal hypertension. Sodium ferulate (SF) has been shown to decrease the production of geranylgeranyl pyrophosphate (GGPP), a substance essential for RhoA activation. In the present study, to investigate the effects of SF on fibrosis, portal hypertension and the RhoA/Rho-kinase pathway, hepatic cirrhosis was induced in rats by bile duct ligation. Liver function and fibrogenesis-related biochemical parameters, the hepatic hydroxyproline content, the pathological characteristics of the liver sections and the levels of hepatic α-smooth muscle actin (α-SMA; by immunohistochemistry) were analyzed to assess effects of SF on hepatic fibrosis. In addition, hepatic RhoA, Rho-kinase and endothelial nitric oxide synthase (eNOS) expression was examined by immunohistochemistry. Apoptosis in the SF-treated and SF + GGPP-treated rat primary hepatic stellate cells (HSCs) and a human stellate cell line (LX-2) was examined by flow cytometry. Intrahepatic resistance and responsiveness to the α1-adrenoceptor agonist, methoxamine, were investigated by in situ liver perfusion. Treatment with SF did not affect fibrosis-related biochemical parameters or the hydroxyproline content; however, SF reduced the histological evidence of fibrosis and hepatocyte damage. The SF-treated rats had a significantly lower expression of α-SMA and Rho-kinase, as well as an increased hepatic eNOS content; however, SF did not affect RhoA expression. The SF-treated HSCs had a significantly increased apoptotic rate compared to the untreated rats. Following the addition of GGPP, the rate apoptotic rate decreased. SF reduced basal intrahepatic resistance and the responsiveness of hepatic vascular smooth muscle to methoxamine. Therefore, our data demonstrate that SF reduces fibrogenesis, decreases portal pressure in cirrhotic rats and inhibits the activation of the RhoA/Rho-kinase signaling pathway.

Shed Syndecan-1 is involved in chemotherapy resistance via the EGFR pathway in colorectal cancer

Background:

Syndecan-1 (Sdc-1) shedding induced by matrix metalloproteinase-7 (MMP-7) and additional proteases has an important role in cancer development. However, the impact of Sdc-1 shedding on chemotherapeutic resistance has not been reported.

Methods:

We examined Sdc-1 shedding in colorectal cancer by enzyme-linked immunosorbent assay (ELISA), Dot blot, reverse transcription-PCR (RT-PCR), immunohistochemistry and so on, its impact on chemotherapeutic sensitivity by collagen gel droplet embedded culture-drug sensitivity test (CD-DST) and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide), and potential mechanisms of action by Dot blot, western blot and immunofluorescence.

Results:

Sdc-1 shedding was increased in colorectal cancer patients, Sdc-1 serum levels in postoperative patients were lower than in preoperative patients, but still higher than those observed in healthy adults. Patients with high preoperative Sdc-1 serum levels were less responsive to 5-Fluorouracil, Oxaliplatin, Irintecan, Cisplatin or Paclitaxel chemotherapy. Moreover, the disease-free survival of patients with high preoperative Sdc-1 serum levels was significantly poorer. The possible mechanism of chemotherapy resistance in colorectal cancer can be attributed to Sdc-1 shedding, which enhances EGFR phosphorylation and downstream signalling.

Conclusions:

Shed Sdc-1 is involved in chemotherapy resistance via the EGFR pathway in colorectal cancer, and Sdc-1 serum levels could be a new prognostic marker in colorectal cancer.

Effect of nitric oxide pathway regulation on water/sodium balance and renal function in a rodent model of acute liver and renal failure

BACKGROUND

The pathomechanism of acute hepatorenal syndrome (HRS), a particular form of acute renal failure that occurs in the course of acute liver injury, is still poorly understood. The aim of our study was to estimate the influence of the activation and inhibition of the nitric oxide pathway on the water/sodium balance and development of acute renal failure in the course of HRS.

MATERIAL AND METHODS

We used male Sprague-Dawley rats in the acute galactosamine (Ga1N) model of HRS. The nitric oxide synthase (NOS) inhibitors L-NAME and L-arginine were administered intraperitoneally before and after liver damage.

RESULTS

HRS developed in all tested groups. L-NAME increased osmotic clearance and urine volume more effectively before liver injury. Furthermore, administration of L-NAME increased creatinine clearance both before and after Ga1N injection. A double dose of L-NAME did not yield further improvement before Ga1N injection, but improved creatinine clearance after Ga1N intoxication. Injection of L-arginine increased sodium excretion and urine volume, but only after liver injury. Moreover, L-arginine injected after Ga1N caused significant improvement of the creatinine clearance in a dose-dependent manner.

CONCLUSIONS

Our study shows that inhibition of the nitric oxide pathway improves parameters of water and sodium balance and prevents development of acute renal failure in the course of acute liver injury and liver failure. Activation of the nitric oxide system also has a favorable influence on water/sodium balance and renal failure, but only after liver injury.

Effect of laparoscopic splenectomy on portal haemodynamics in patients with liver cirrhosis and portal hypertension

BACKGROUND

The effect of splenomegaly in patients with liver cirrhosis and portal hypertension is not fully understood. This study was designed to determine the effect of laparoscopic splenectomy on portal haemodynamics in these patients.

METHODS

Patients with liver cirrhosis and portal hypertension who underwent laparoscopic splenectomy in Kyushu University Hospital from January 2006 to March 2009 were evaluated retrospectively. Correlations between splenic size and portal haemodynamics, and changes in portal haemodynamics and in levels of the vasoactive agents endothelin (ET) 1 and nitric oxide metabolites (NOx) before and 7-10 days after laparoscopic splenectomy were analysed.

RESULTS

Portal venous (PV) blood flow, PV cross-sectional area and PV congestion index correlated significantly with splenic size (P < 0·050). All three were significantly reduced following splenectomy in 59 patients. The hepatic venous pressure gradient, measured in 18 patients, decreased by 25 per cent after splenectomy (P < 0·001). Portal vascular resistance was also reduced, by 21 per cent (P = 0·009). The peripheral blood concentration of ET-1 decreased from 2·95 to 2·11 pg/ml (P < 0·001), and that of NOx tended to decrease (from 29·2 to 25·0 pg/ml; P = 0·068). In hepatic venous blood, the level of ET-1 decreased from 2·37 to 1·83 pg/ml (P = 0·006), whereas NOx concentration tended to increase (from 24·5 to 30·9 pg/ml; P = 0·067).

CONCLUSION

In patients with liver cirrhosis and portal hypertension, splenectomy reduced portal venous pressure. A decrease in splanchnic blood flow, by eliminating splenic blood flow, and reduction in intrahepatic vascular resistance, by normalizing hepatic concentrations of ET-1 and NOx, may both have contributed.

Autophagy enhances hepatocellular carcinoma progression by activation of mitochondrial β-oxidation

BACKGROUND

Several types of cancers, including hepatocellular carcinoma (HCC), show resistance to hypoxia and nutrient starvation. Autophagy is a means of providing macromolecules for energy generation under such stressed-conditions. The aim of this study was to clarify the role of autophagy in HCC development under hypoxic conditions.

METHODS

The expression of microtubule-associated protein 1 light chain 3 (LC3), which is a key gene involved in autophagosome formation, was evaluated in human HCC using immunohistochemistry and western blot. The relationship between LC3 and hypoxia-induced factor 1α (HIF1α) expression was examined using real-time PCR. In addition, human HCC cell line Huh7 was treated with pharmacological autophagy-inhibitor and inactive mutant of Atg4B (Atg4B(C74A)) under hypoxic condition to evaluate the effects of hypoxia-induced autophagy on cell survival, intracellular ATP, and mitochondrial β-oxidation.

RESULTS

LC3 was significantly highly expressed in HCC as compared with noncancerous tissues. LC3 expression, correlated with HIF1α expression, was also significantly correlated with tumor size, and only in the context of large tumors, was an independent predictor of HCC recurrence after surgery. In addition, Huh7 treated with autophagy-inhibitor under hypoxia had lower viability, with low levels of intracellular ATP due to impaired mitochondrial β-oxidation.

CONCLUSIONS

Autophagy in HCC works to promote HIF1α-mediated proliferation through the maintenance of intracellular ATP, depending on the activation of mitochondrial β-oxidation. These findings demonstrated the feasibility of anti-autophagic treatment as a potential curative therapy for HCC, and improved understanding of the factors determining adaptive metabolic responses to hypoxic conditions.

Effects of fasudil on the portal and systemic hemodynamics of patients with cirrhosis

BACKGROUND AND AIM

Fasudil, a Rho-kinase inhibitor, has been shown to reduce portal venous pressure in cirrhotic rats. However, its effects on portal and systemic hemodynamics have not been investigated in cirrhotic patients with portal hypertension. The aim of this study was to assess the effects of fasudil on the portal and systemic hemodynamics of cirrhotic patients with portal hypertension.

METHODS

Twenty-three patients with cirrhosis and portal hypertension were studied. Systemic and portal hemodynamics were measured prior to and 50 min after the initiation of intravenous administration of 30 mg fasudil (n = 15) or placebo (n = 8).

RESULTS

After fasudil, there were significant decreases in both mean arterial pressure (P < 0.05) and systemic vascular resistance (P < 0.05), whereas the heart rate increased significantly (P < 0.05). There was a significant decrease in the hepatic venous pressure gradient (P < 0.05). Portal vascular resistance also decreased significantly (P < 0.01). Placebo caused no significant effects. There were no symptomatic reactions caused by changes in the mean arterial pressure or heart rate after fasudil.

CONCLUSIONS

In cirrhotic patients with portal hypertension, fasudil lowers portal vascular resistance, resulting in decreased portal venous pressure with reducing arterial pressure.

Current concepts on the role of nitric oxide in portal hypertension

Portal hypertension (PHT) is defined as a pathological increase in portal venous pressure and frequently accompanies cirrhosis. Portal pressure can be increased by a rise in portal blood flow, an increase in vascular resistance, or the combination. In cirrhosis, the primary factor leading to PHT is an increase in intra-hepatic resistance to blood flow. Although much of this increase is a mechanical consequence of architectural disturbances, there is a dynamic and reversible component that represents up to a third of the increased vascular resistance in cirrhosis. Many vasoactive substances contribute to the development of PHT. Among these, nitric oxide (NO) is the key mediator that paradoxically regulates the sinusoidal (intra-hepatic) and systemic/splanchnic circulations. NO deficiency in the liver leads to increased intra-hepatic resistance while increased NO in the circulation contributes to the hyperdynamic systemic/splanchnic circulation. NO mediated-angiogenesis also plays a role in splanchnic vasodilation and collateral circulation formation. NO donors reduce PHT in animals models but the key clinical challenge is the development of an NO donor or drug delivery system that selectively targets the liver.

Endothelin-1 derived from spleen-activated Rho-kinase pathway in rats with secondary biliary cirrhosis

AIM

  Splenectomy or partial splenic embolism has been reported to improve liver function in patients with hypersplenism and liver dysfunction. The aim of this study was to investigate the mechanism of improvement after splenectomy.

METHODS

  Liver cirrhosis was induced by bile duct ligation (BDL). Rats underwent sham operation, splenectomy (Sp group), BDL, or BDL plus splenectomy (BDL + Sp group), and were subjected to experiments at 2 weeks after the operation. Portal venous pressure (PVP) and hepatic tissue blood flow (HTBF) were measured in each group. The plasma concentration of endothelin-1 (ET-1) and endothelial nitric oxide synthase (eNOS), RhoA and Rho-kinase expressions were studied.

RESULTS

  There were significant differences in PVP (17.9 ± 0.91 vs 23.3 ± 3.91 cmH(2) O; P < 0.01) and HTBF (16.6 ± 1.72 vs 13.3 ± 1.82 mL/min; P < 0.01) between the BDL + Sp and BDL groups. In the liver of BDL rats, eNOS phosphorylation and NOx levels were decreased, accompanied by RhoA activation compared with the BDL + Sp group. Splenectomy decreased serum ET-1 levels, RhoA activation and consequently increased eNOS phosphorylation.

CONCLUSION

  ET-1 derived from the spleen might increase intrahepatic resistance by downregulating Rho signaling in liver cirrhosis. Splenectomy for splenomegaly in liver cirrhosis might partially improve liver function by enhancing intrahepatic microcirculation.

Antagonism of sphingosine 1-phosphate receptor 2 causes a selective reduction of portal vein pressure in bile duct-ligated rodents

Sinusoidal vasoconstriction, in which hepatic stellate cells operate as contractile machinery, has been suggested to play a pivotal role in the pathophysiology of portal hypertension. We investigated whether sphingosine 1-phosphate (S1P) stimulates contractility of those cells and enhances portal vein pressure in isolated perfused rat livers with Rho activation by way of S1P receptor 2 (S1P(2) ). Rho and its effector, Rho kinase, reportedly contribute to the pathophysiology of portal hypertension. Thus, a potential effect of S1P(2) antagonism on portal hypertension was examined. Intravenous infusion of the S1P(2) antagonist, JTE-013, at 1 mg/kg body weight reduced portal vein pressure by 24% without affecting mean arterial pressure in cirrhotic rats induced by bile duct ligation at 4 weeks after the operation, whereas the same amount of S1P(2) antagonist did not alter portal vein pressure and mean arterial pressure in control sham-operated rats. Rho kinase activity in the livers was enhanced in bile duct-ligated rats compared to sham-operated rats, and this enhanced Rho kinase activity in bile duct-ligated livers was reduced after infusion of the S1P(2) antagonist. S1P(2) messenger RNA (mRNA) expression, but not S1P(1) or S1P(3) , was increased in bile duct-ligated livers of rats and mice and also in culture-activated rat hepatic stellate cells. S1P(2) expression, determined in S1P 2LacZ/+ mice, was highly increased in hepatic stellate cells of bile duct-ligated livers. Furthermore, the increase of Rho kinase activity in bile duct-ligated livers was observed as early as 7 days after the operation in wildtype mice, but was less in S1P 2-/- mice.

CONCLUSION

S1P may play an important role in the pathophysiology of portal hypertension with Rho kinase activation by way of S1P(2) . The S1P(2) antagonist merits consideration as a novel therapeutic agent for portal hypertension.

Strain of experimental animals and modulation of nitric oxide pathway: their influence on development of renal failure in an experimental model of hepatorenal syndrome

INTRODUCTION

Pathomechanism of HRS is still poorly understood. The aim of our study was: (1) to test whether different strains of rats could develop typical HRS, and (2) to estimate the influence of activation and inhibition of nitric oxide for development of renal failure in course of HRS.

MATERIAL AND METHODS

First, we used 16 of Wistar and 16 of Sprague-Dawley rats in galactosamine model of HRS. Next, we used 48 of SDR rats, which received saline, N-nitro-L-arginine or L-arginine before and after liver damage. Twenty four hours urine and blood samples were collected 48 h after saline or Ga1N injection. Biochemical parameters were determined in serum or urine and then creatinine clearance and osmolality clearance were calculated. Liver and kidney tissues were collected for histopathological examination.

RESULTS

Liver failure developed in all tested groups with significant increase of bilirubin (p < 0.001), ALT (p < 0.001) and ammonia (p < 0.001). Nevertheless we did not achieve any evidence of renal failure in Wistar, but we found typical renal failure in Sprague-Dawley group with significant decrease in creatinine clearance (p < 0.0012) and increase in concentration of creatinine and urea (p < 0.001) and (p < 0.001) respectively. Inhibition of NOS prevented development of renal failure with significant improvement of GFR both before (p < 0.0017) and after (p < 0.003) Ga1N injection. Injection of L-arginine after Ga1N injection did not caused significant improvement of GFR.

CONCLUSIONS

Our study showed, that genetic factors might be responsible for development of renal failure in course of HRS and nitric oxide play important role in acute model of this syndrome.

Diacylglycerol kinase alpha enhances hepatocellular carcinoma progression by activation of Ras-Raf-MEK-ERK pathway

BACKGROUND & AIMS

Diacylglycerol kinases (DGKs) were recently recognized as key regulators in cell signaling pathways. We investigated whether DGKα is involved in human hepatocellular carcinoma (HCC) progression.

METHODS

We silenced or overexpressed DGKα in HCC cells and assessed its effect on tumor progression. DGKα expression in 95 surgical samples was analyzed by immunohistochemistry, and the expression status of each sample was correlated with clinicopathological features.

RESULTS

DGKα was detected in various HCC cell lines but at very low levels in the normal liver. Knockdown of DGKα significantly suppressed cell proliferation and invasion. Overexpression of wild type (WT) DGKα, but not its kinase-dead (KD) mutant, significantly enhanced cell proliferation. DGKα knockdown impaired MEK and ERK phosphorylation, but did not inhibit Ras activation in HCC cells. In a xenograft model, WT DGKα overexpression significantly enhanced tumor growth compared to the control, but KD DGKα mutant had no effect. Immunohistochemical studies showed that DGKα was expressed in cancerous tissue, but not in adjacent non-cancerous hepatocytes. High DGKα expression (≥20%) was associated with high Ki67 expression (p<0.05) and a high rate of HCC recurrence (p=0.033) following surgery. In multivariate analyses, high DGKα expression was an independent factor for determining HCC recurrence after surgery.

CONCLUSIONS

DGKα is involved in HCC progression by activation of the MAPK pathway. DGKα could be a novel target for HCC therapeutics as well as a prognostic marker.

Rho inhibitor prevents ischemia-reperfusion injury in rat steatotic liver

BACKGROUND & AIMS

Hepatic stellate cells are thought to play a role in modulating intrahepatic vascular resistance based on their capacity to contract via Rho signaling. We investigated the effect of a Rho-kinase inhibitor on ischemia-reperfusion injury in the steatotic liver.

METHODS

Steatotic livers, induced by a choline-deficient diet in rats, were subjected to ischemia-reperfusion injury. Hepatic stellate cells isolated from steatotic livers were analyzed for contractility and Rho signaling activity. The portal pressure of the perfused rat liver and the survival rate after ischemia-reperfusion were also investigated.

RESULTS

Hepatic stellate cells from steatotic livers showed increased contractility and upregulation of Rho-kinase 2 compared with those from normal livers. Furthermore, endothelin-1 significantly enhanced the contractility and phosphorylation level of myosin light chain and cofilin in hepatic stellate cells isolated from steatotic livers. A specific Rho-kinase inhibitor, fasudil, significantly suppressed the contractility and decreased the phosphorylation levels of myosin light chain and cofilin. Serum levels of endothelin-1 were markedly increased after IR in rats with steatotic livers, whereas fasudil significantly decreased endothelin-1 serum levels. Rats with steatotic livers showed a significant increase in portal perfusion pressure after ischemia-reperfusion and a significant decrease in survival rate; fasudil treatment significantly reduced these effects.

CONCLUSIONS

Activation of Rho/Rho-kinase signaling in hepatic stellate cells isolated from steatotic livers is associated with an increased susceptibility to ischemia-reperfusion injury. A Rho-kinase inhibitor attenuated the activation of hepatic stellate cells isolated from steatotic livers and improved ischemia-reperfusion injury in steatotic rats.

Roles of vascular endothelial growth factor and endothelial nitric oxide synthase during revascularization and regeneration after partial hepatectomy in a rat model

PURPOSE

Angiogenesis is an essential process in liver regeneration. Nitric oxide (NO) and vascular endothelial growth factor (VEGF) are the main regulators of normal and pathological angiogenesis. This study aimed to determine the roles of NO derived from endothelial nitric oxide synthase (eNOS) and VEGF in sinusoidal endothelial cell (SEC) proliferation during liver regeneration.

METHODS

Sprague-Dawley rats underwent a 70% partial hepatectomy (PHx), and were euthanized 0, 24, 48, 72, or 168 h later. Liver regeneration and SEC proliferation were evaluated. The protein expression of VEGF and eNOS was examined by a Western blot analysis. The rats were also treated with the NO synthase inhibitor N (G)-nitro-L-arginine-methyl ester (L-NAME) to examine its effects on liver regeneration and SEC proliferation.

RESULTS

The proliferating cell nuclear antigen (PCNA) labeling index of hepatocytes was significantly increased at 24 h after PHx. The eNOS protein expression and NO production were significantly increased from 72 to 168 h. The expression of VEGF protein was significantly increased at 72 h. L-NAME significantly inhibited the increases in the liver mass and decreased the PCNA labeling index of hepatocytes at 24 h. L-NAME also inhibited the induction of VEGF protein at 72 h.

CONCLUSIONS

Endothelial NOS and VEGF coordinately regulate SEC proliferation during liver regeneration. Sinusoidal endothelial cell proliferation is necessary and is an important step in liver regeneration.

Liver regeneration is promoted by increasing serotonin content in rat liver with secondary biliary cirrhosis

AIM

  Liver cirrhosis clinically shows thrombocytopenia and hypersplenism. Although splenectomy is performed to achieve higher platelet count and better hemostasis, the effect of splenectomy for liver cirrhosis remains unclear. The aim of the present study that was focused on serotonin was to investigate the relationship between splenectomy and liver regeneration in rats with secondary biliary cirrhosis.

METHODS

  Liver cirrhosis was induced in Sprague-Dawley rats by bile duct ligation (BDL). In addition, splenectomy and administration of ketanserin, which selectively antagonizes 5-HT2A and 2B serotonin receptors, were performed. Three weeks after the interventions, whole blood, plasma, serum, and liver specimens were obtained for the following studies: peripheral platelet counts, hemodynamics of serotonin, histopathological examination, immunostaining, and quantification of mRNA expression.

RESULTS

  Splenectomy induced thrombocytosis, and increased serotonin content in cirrhotic liver. Stimulation of liver regeneration was indicated by the following parameters: hepatocyte ratio to the entire liver area, Ki67-positive hepatocyte count, and expression of phosphorylated extracellular signal-regulated kinases. This enhancement of liver regeneration was negated by ketanserin.

CONCLUSION

  Our results showed that splenectomy promoted liver regeneration by increasing serotonin content in liver even under cirrhotic conditions.

TGF-β1 mediated activation of Rho kinase induces TGF-β2 and endothelin-1 expression in human hepatic stellate cells

BACKGROUND & AIMS

TGF-β1 a key pro-fibrotic factor activates signaling via the canonical ALK/SMAD as well as the Rho GTPase pathways. Rho kinase is a major downstream effector of Rho GTPase signaling. To understand the contribution of Rho kinase activation towards the synthesis of fibrotic mediators by hepatic stellate cells (HSC), we first profiled activated HSC and fibrotic liver tissues to identify common transcripts that were most significantly up-regulated across all samples. We then applied a pharmacologic as well as a genomics approach in a TGF-β1 activated human HSC line (LX-2) to study the involvement of Rho kinase signaling in the expression of a subset of these up-regulated fibrotic genes.

METHODS

Total RNA was profiled using microarray chips. Data analysis was performed using Ingenuity Pathway Analysis software. LX-2 cells were activated with 10 ng/ml of TGF-β1 for 24 h. Activation of downstream pathways was assessed by Western blotting with phospho-specific target biomarker antibodies. Targeted knockdown of Rho kinase isoforms 1 and 2 was achieved with RNAi. Secreted levels of endothelin-1, TGF-β2, and thrombospondin-1 were measured by ELISA.

RESULTS

TGF-β1 activated Rho kinase and Smad pathways in LX-2 cells. The syntheses of endothelin-1 and TGF-β2 were significantly inhibited in TGF-β1 treated LX-2 cells, by isoform non-selective Rho kinase inhibitors. siRNA knockdown of each isoform suggested that endothelin-1 synthesis was largely mediated by the Rho kinase-1 isoform, while both isoforms contributed to the synthesis of TGF-β2.

CONCLUSIONS

The TGF-β1 mediated secretion of endothelin-1 and TGF-β2 is mediated by Rho kinase activation in human HSC.

Treatment with the leukotriene inhibitor montelukast for 10 days attenuates portal hypertension in rat liver cirrhosis

The mechanisms underlying intrahepatic vasoconstriction are not fully elucidated. Here we investigated the Kupffer cell (KC)-dependent increase in portal pressure by way of actions of vasoconstrictive cysteinyl leukotrienes (Cys-LTs). Liver cirrhosis was induced in rats by bile duct ligation (BDL for 4 weeks; controls: sham-operation) and thioacetamide application (18 weeks). Infusion of leukotriene (LT) C(4) or LTD(4) in isolated perfused livers (20 nM, BDL and sham) demonstrated that LTC(4) is a more relevant vasoconstrictor. In BDL animals the Cys-LT(1) receptor inhibitor montelukast (1 microM) reduced the maximal portal perfusion pressure following LTC(4) or LTD(4) infusion. The infusion of LTC(4) or D(4) in vivo (15 microg/kg b.w.) confirmed LTC(4) as the more relevant vasoconstrictor. Activation of KCs with zymosan (150 microg/mL) in isolated perfused BDL livers increased the portal perfusion pressure markedly, which was attenuated by LT receptor blockade (Ly171883, 20 microM). Cys-LTs in the effluent perfusate increased with KC activation but less with additional blockade of KCs with gadolinium chloride (10 mg/kg body weight, 48 and 24 hours pretreatment). KCs were isolated from normal rat livers and activated with zymosan or lipopolysaccharide at different timepoints. This resulted in an increase in Cys-LT production that was not influenced by preincubation with montelukast (1 microM). Infusion of LTC(4) (20 nM) and the thromboxane analog U46619 (0.1 microM) further enhanced portal pressure, indicating additive effects. Treatment with montelukast for 10 days resulted in an impressive reduction in the basal portal pressure and an attenuation of the KC-dependent increase in portal pressure.

CONCLUSION

Activation of isolated KCs produced Cys-LTs. Infusion of Cys-LTs increased portal pressure and, vice versa, treatment with montelukast reduced portal pressure in rat liver cirrhosis. Therefore, montelukast may be of therapeutic benefit for patients with portal hypertension.

Sex-dependent differences in Rho activation contribute to contractile dysfunction in type 2 diabetic mice

The objective of this study was to determine if mechanisms involved in vascular dysfunction in type 2 diabetes differ with sex. Vascular reactivity, expression, and activation of rhoA and rho kinase were measured in aorta from male and female nondiabetic C57BLKS/J and diabetic BKS.Cg-m(+/+) Lepr(db)/J (db/db) mice, a model of type 2 diabetes. Relaxation to acetylcholine and nitroprusside was similar in aorta from nondiabetic male and female mice. Relaxation to acetylcholine was reduced approximately 50% in both male and female diabetic mice. Although inhibition of rho kinase with H-1152 increased relaxation to acetylcholine and nitroprusside in nondiabetic males, it had no effect on the response in either nondiabetic or diabetic females or diabetic males. Contraction to serotonin was increased similarly in male and female diabetic mice compared with nondiabetic mice and was reduced following inhibition of rho kinase with either fasudil or H-1152. Activation of rhoA and its downstream effector, rho kinase, was greater in aorta from diabetic males compared with nondiabetic males. In contrast, there were no differences in vascular activation of rhoA or rho kinase in diabetic females. The increased activity of rhoA and rho kinase in diabetic mice was not due to a change in protein expression of rhoA or rho kinase (ROCK1 and ROCK2) in vessels from either males or females. Although contractile dysfunction in vessels occurs in both male and female diabetic mice, the dysfunction in diabetic males is dependent upon activation of rhoA and rho kinase. Alternative mechanisms affecting rho kinase activation may be involved in females.

Lack of effect of norfloxacin on hyperdynamic circulation in bile duct-ligated rats despite reduction of endothelial nitric oxide synthase function: result of unchanged vascular Rho-kinase?

BACKGROUND/AIMS

In cirrhosis, portal hypertension is maintained by splanchnic vasodilation owing to overproduction of the vasodilator nitric oxide (NO) and defective contractile signalling by Rho-kinase. NO overproduction is partially caused by bacterial translocation from the gut to mesenteric lymph nodes. However, the effects of intestinal bacterial decontamination on hyperdynamic circulation or vascular contractility are unknown. We investigated the haemodynamic and vascular effects of norfloxacin in rats with secondary biliary cirrhosis.

METHODS

Cirrhosis was induced by bile duct ligation (BDL). One group was treated with norfloxacin (20 mg/kg/day, 5 days, orally). Bacterial growth in the lymph nodes was determined on blood agar plates. Invasive haemodynamic measurements were combined with coloured microspheres. Aortic contractility was assessed myographically. Protein expression/phosphorylation was examined by Western blot analysis.

RESULTS

Norfloxacin treatment of BDL rats abolished bacterial translocation to mesenteric lymph nodes. BDL rats had hyperdynamic circulation, including portal hypertension and splanchnic vasodilation. None of these parameters was changed by norfloxacin, although norfloxacin reduced endothelial NO synthase expression and phosphorylation. The latter was associated with a diminished activity of protein kinase G (PKG), which mediates NO-induced vasodilation. However, norfloxacin had no effect on aortic contractility to methoxamine or Ca2+, or the aortic expression of RhoA, Rho-kinase and beta-arrestin 2, or the phosphorylation of the Rho-kinase substrate moesin.

CONCLUSIONS

Short-term treatment of BDL rats with norfloxacin does not change hyperdynamic circulation or vascular contractility, despite reduction of PKG activity.

Sorafenib targets dysregulated Rho kinase expression and portal hypertension in rats with secondary biliary cirrhosis

BACKGROUND AND PURPOSE

Extrahepatic vasodilation and increased intrahepatic vascular resistance represent attractive targets for the medical treatment of portal hypertension in liver cirrhosis. In both dysfunctions, dysregulation of the contraction-mediating Rho kinase plays an important role as it contributes to altered vasoconstrictor responsiveness. However, the mechanisms of vascular Rho kinase dysregulation in cirrhosis are insufficiently understood. They possibly involve mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)-dependent mechanisms in extrahepatic vessels. As the multikinase inhibitor sorafenib inhibits ERK, we tested the effect of sorafenib on haemodynamics and dysregulated vascular Rho kinase in rats with secondary biliary cirrhosis.

EXPERIMENTAL APPROACH

Secondary biliary cirrhosis was induced by bile duct ligation (BDL). Sorafenib was given orally for 1 week (60 mg.kg(-1).d(-1)). Messenger RNA levels were determined by quantitative real time polymerase chain reaction, protein expressions and protein phosphorylation by Western blot analysis. Aortic contractility was studied by myographic measurements, and intrahepatic vasoregulation by using livers perfused in situ. In vivo, haemodynamic parameters were assessed invasively in combination with coloured microspheres.

KEY RESULTS

In BDL rats, treatment with sorafenib decreased portal pressure, paralleled by decreases in hepatic Rho kinase expression and Rho kinase-mediated intrahepatic vascular resistance. In aortas from BDL rats, sorafenib caused up-regulation of Rho kinase and an improvement of aortic contractility. By contrast, mesenteric Rho kinase remained unaffected by sorafenib.

CONCLUSIONS AND IMPLICATIONS

Intrahepatic dysregulation of vascular Rho kinase expression is controlled by sorafenib-sensitive mechanisms in rats with secondary biliary cirrhosis. Thus, sorafenib reduced portal pressure without affecting systemic blood pressure.

Advances in drug treatment of portal hypertension

Intrahepatic vascular resistance augmentation and portal blood flow increase are main mechanisms of portal hypertension. The former as an initial factor is mainly due to liver structure changes and motivity changes (reversible). It has been demonstrated that this reversible resistance can be reduced by 20%-30% with drugs. Portosystemic shunt or transjugular intrahepatic portosystemic shunt (TIPS) may induce many severe complications such as hepatic encephalopathy and stent re-obstruction. Therefore, researchers have performed plenty of experimental investigations about drug treatment of portal hypertension, and this article introduces their new advances in this field.