Decrease in the hepatic clearance of hepatocyte growth factor in carbon tetrachloride-intoxicated rats

Therapeutic potential of Vanillylacetone against CCl4 induced hepatotoxicity by suppressing the serum marker, oxidative stress, inflammatory cytokines and apoptosis in Swiss albino mice

The aim of this research was to investigate the therapeutic potential of Vanillylacetone against carbon tetrachloride (CCl₄) induced hepatotoxicity in mice through understanding the serum marker, oxidative stress mechanism and cytokine networks. Carbon tetrachloride is highly hepatotoxic used as research based on animal model. The mice were classified into five groups and each had eight mice. Group-I was controlled and the vehicle was given orally. Group-II was toxic and carbon tetrachloride (1.5 ml/kg) twice a week for 15 days was administered by intra-peritoneal injections. Group- III and IV were pre-treated with Vanillylacetone 50 & 100 mg kg^-1 body weight given every day p.o. while, Group-V received only Vanillylacetone (100 mg kg^-1 body weight) for 15 days orally. The finding indicates that the administration of CCl₄ causes significant elevation of enzyme markers, oxidative stress, inflammatory cytokine and apoptotic markers in Group-II as compared to Group-I. The administration of Vanillylacetone (50 and100 mg kg^-1) significantly suppresses the elevated serum enzymes, oxidative stress (TBARS), an inflammatory cytokine (IL2 and TNFα) and apoptotic markers (Caspase-3 and 9) in Group-III and IV as compared to Group-II. It was also noticed that the higher dose of Vanillylacetone (100 mg) is more effective than lower dose of Vanillylacetone (50 mg). There were no significant changes observed with higher dose of Vanillylacetone (100 mg kg^-1) in Group-V as compared to Group-I. Histopathological analysis also supported the above findings. Overall, this results shows that Vanillylacetone has a good antioxidant and therapeutic properties which can help in preventing the chemically (CCl₄) induced hepatotoxicity.

Liver uptake of cefditoren is mediated by OATP1B1 and OATP2B1 in humans and Oatp1a1, Oatp1a4, and Oatp1b2 in rats

OATPs and Oatps mediated liver uptake of cefditoren in humans and in rats.

Flavonoids from Heliotropium subulatum exudate and their evaluation for antioxidant, antineoplastic and cytotoxic activities II

The flavonoids are the largest group of phenolic compounds isolated from a wide range of higher plants. These compounds work as antimicrobials, anti-insect agents and protect plants from other types of biotic and abiotic stresses. Various researchers have suggested that flavonoids possessed antioxidant, antineoplastic and cytotoxic activities. The main objective of this study was to test dichloromethane fraction of resinous exudate of Heliotropium subulatum for their antioxidant, antineoplastic and cytotoxic activities, as well as to search new antioxidant and antineoplastic agents for pharmaceutical formulations. Five flavonoids were isolated from resinous exudate of this plant species and screened for their in vitro and in vivo antioxidant models (DPPH radical scavenging, reducing power, superoxide anion scavenging, metal chelating scavenging systems, catalase and lipid peroxidation), antineoplastic (Sarcoma 180), and cytotoxic (Chinese hamster V79 cells) activities. Tricetin demonstrated maximum antioxidant activity against both in vitro and in vivo experimental systems while galangin exhibited maximum inhibition (78.35%) at a dose of 10 µg/kg/day against Sarcoma 180. Similarly, it was found that galangin also showed highest activity (21.1 ± 0.15%) at a concentration of 70 µg/ml to Chinese hamster V79 cells. The observed results suggest that tricetin has a potential to scavenge free radicals in both in vitro and in vivo models while the galangin could be considered as antitumor and cytotoxic agent.

Liver Failure Impairs the Intrahepatic Elimination of Interleukin-6, Tumor Necrosis Factor-Alpha, Hepatocyte Growth Factor, and Transforming Growth Factor-Beta

The strategic location of the liver and its metabolic activity make it a key organ regulating homeostasis. Our purpose was to examine its participation in removal of cytokines: interleukin-6 (Il-6), tumor necrosis factor-alpha (TNF-α), hepatocyte growth factor (HGF), and transforming growth factor-beta (TGF-β) from the portal circulation in human. 20 liver donors and 20 patients with end-stage liver failure were included in the study. Their blood was collected during liver transplantation from the portal, hepatic, and peripheral vein, and the hepatic artery and cytokines' concentrations were determined. Using the results the mathematical model of cytokine elimination by the liver was developed. In donors significantly lower levels of IL-6, TNF-α, HGF, and TGF-β were detected in portal blood compared to hepatic vein. In patients with cirrhosis there were no significant differences of IL-6, TNF-α, and TGF-β levels between portal and hepatic veins. Significantly higher level of HGF in hepatic compared to portal vein was observed. In healthy liver elimination of the cytokines prevailed over their synthesis, as reflected by the positive values of the elimination ratios. In the cirrhotic liver elimination ratios of Il-6, HGF, and TGF-β were negative indicating the prevalence of intrahepatic synthesis of cytokines over their removal.

FTY720, a sphingosine-1 phosphate receptor modulator, improves liver fibrosis in a mouse model by impairing the motility of bone marrow-derived mesenchymal stem cells

FTY720 is a novel immunosuppressant that modulates sphingosine 1-phosphate (S1P) receptors for the treatment of several diseases. Several hallmarks of liver fibrosis are influenced by S1P, and the interference of S1P signaling by treatment with FTY720 results in beneficial effects in various animal models of fibrosis. However, whether these treatment strategies suppress liver fibrosis progression is incompletely understood. Here, we investigated the effects and mechanisms by which FTY720 improves liver fibrosis in the carbon tetrachloride (CCl4)-induced mouse model. FTY720 treatment significantly attenuated the expression of fibrotic markers in the injured liver of both wild-type and SCID-beige mice. The migration of bone marrow-derived mesenchymal stem cells (BMSCs) to circulation, and subsequently the injured liver, was suppressed by FTY720. Furthermore, in vitro, phosphorylated-FTY720 blocked the migration of BMSCs mediated by S1P. Thus, FTY720 is an effective therapy for liver fibrosis via the suppression of BMSC migration in the CCl4-induced mouse model.

Rodent models and imaging techniques to study liver regeneration

The liver has the unique capability of regeneration from various injuries. Different animal models and in vitro methods are used for studying the processes and mechanisms of liver regeneration. Animal models were established either by administration of hepatotoxic chemicals or by surgical approach. The administration of hepatotoxic chemicals results in the death of liver cells and in subsequent hepatic regeneration and tissue repair. Surgery includes partial hepatectomy and portal vein occlusion or diversion: hepatectomy leads to compensatory regeneration of the remnant liver lobe, whereas portal vein occlusion leads to atrophy of the ipsilateral lobe and to compensatory regeneration of the contralateral lobe. Adaptation of modern radiological imaging technologies to the small size of rodents made the visualization of rodent intrahepatic vascular anatomy possible. Advanced knowledge of the detailed intrahepatic 3D anatomy enabled the establishment of refined surgical techniques. The same technology allows the visualization of hepatic vascular regeneration. The development of modern histological image analysis tools improved the quantitative assessment of hepatic regeneration. Novel image analysis tools enable us to quantify reliably and reproducibly the proliferative rate of hepatocytes using whole-slide scans, thus reducing the sampling error. In this review, the refined rodent models and the newly developed imaging technology to study liver regeneration are summarized. This summary helps to integrate the current knowledge of liver regeneration and promises an enormous increase in hepatological knowledge in the near future.

Pharmacokinetics and pharmacodynamics following intravenous administration of recombinant human hepatocyte growth factor in rats with renal injury

BACKGROUND/AIM

Hepatocyte growth factor (HGF) plays a role in the regeneration and protection of the kidney, but little information is available concerning the pharmacokinetics of therapeutic treatment with HGF. In this study, HGF was administered after the onset of renal injury, and pharmacokinetic analysis was performed simultaneously with an efficacious dose.

METHODS

For the study of pharmacodynamics, recombinant human HGF was intravenously administered to rats with glycerol-induced acute kidney injury (AKI). In the pharmacokinetic study, rats subjected to glycerol injection or renal ischemia-reperfusion were used as models of AKI, and rats subjected to 5/6 nephrectomy were used as models of chronic kidney disease (CKD).

RESULTS

After intravenous administration of HGF at doses of 0.5-2.0 mg/kg, the elevation of blood urea nitrogen was suppressed, indicating that HGF had a pharmacodynamic effect. However, no significant difference was seen in the pharmacokinetic parameters such as clearance, distribution volume and half-life between the normal, AKI and CKD groups.

CONCLUSION

The intravenous administration of HGF after the onset of renal dysfunction exerted a pharmacological effect on AKI, and renal injury did not affect the clearance of plasma HGF. This unaffected profile may serve as a base for the safety of HGF during therapeutic administration.

OATP and MRP2-mediated hepatic uptake and biliary excretion of eprosartan in rat and human

BACKGROUND

Eprosartan is an angiotensin II receptor antagonist, used in the treatment of hypertension and heart failure in clinical patients. The objective of this study was to clarify the mechanism underlying hepatic uptake and biliary excretion of eprosartan in rats and humans.

METHODS

Perfused rat liver in situ, rat liver slices, isolated rat hepatocytes and human organic anion-transporting polypeptide (OATP)-transfected cells in vitro were used in this study.

RESULTS

Extraction ratio of eprosartan was decreased by rifampicin in perfused rat livers. Uptake of eprosartan in rat liver slices and isolated rat hepatocytes was significantly inhibited by Oatp modulators such as ibuprofen, digoxin, rifampicin and cyclosporine A, but not by tetraethyl ammonium or p-aminohippurate. Uptake of eprosartan in rat hepatocytes indicated a saturable process. Although uptake of eprosartan in OATP1B3-human embryonic kidney cells (HEK) 293 cells was not observed, significant differences in cellular accumulations of eprosartan between vector- and OATP1B1-Madin-Darby canine kidney strain (MDCK) II cells were found in transcellular transport study. Moreover, cumulative biliary excretion rate of eprosartan in the presence of probenecid (Multidrug resistance-associated protein 2 (Mrp2) inhibitor) was significantly decreased in perfused rat livers. Vectorial basal-to-apical transport of eprosartan was also observed in OATP1B1/MRP2 double transfectants.

CONCLUSIONS

Eprosartan was transported by multiple Oatps (at least Oatp1a1 and Oatp1a4)/Mrp2 in rat and OATP1B1/MRP2, at least, in human.

Synthesis of tetra-substituted imidazoles and 2-imidazolines by Ni(0)-catalyzed dehydrogenation of benzylic-type imines

A one pot methodology using simple imines allowed the formation of N-substituted imidazoles and imidazolines.

Pharmacokinetic modeling of hepatocyte growth factor in experimental animals and humans

Hepatocyte growth factor (HGF) is under development for treatment of renal failure. This study was designed to clarify changes in HGF pharmacokinetics in renal failure and to establish a pharmacokinetic model applicable to single and repeated doses. The plasma concentration profile in mice with glycerol-induced acute renal failure was similar to that in normal mice, indicating a minimal contribution of kidney to systemic clearance of HGF. Nevertheless, accumulation of fluorescein-4-isocyanate-labeled HGF in renal tubules in both cases suggests the occurrence of efficient endocytosis of HGF in kidney. A pharmacokinetic model including plasma and liver compartments was constructed, incorporating both high- and low-affinity receptors for association and subsequent endocytosis of HGF because HGF is eliminated via specific receptor c-Met and heparin-like substance. The model well explained the plasma concentration profiles at all doses examined after bolus injection in animals and humans, and those during infusion in rodents. It includes externalization of receptors, which is negatively regulated by HGF, and can explain the gradual increase in trough concentration during repeated dosing in monkeys. Overall pharmacokinetic profiles of HGF are governed by at least two receptors and are well described by this pharmacokinetic model, which should assist in safe management of clinical trials.

Molecular mechanisms of biliary excretion of cefditoren and the effects of cefditoren on the expression levels of hepatic transporters

Cefditoren, a third generation cephalosporin antibiotics, has been used in clinics extensively. Previous results have indicated that cefditoren is excreted into bile as unchanged form. To investigate whether canalicular membrane transporters of hepatocytes were involved in the biliary excretion of cefditoren, we examined the hepatobiliary disposition of cefditoren using probenecid, novobiocin and verapamil as inhibitors of Mrp2, Bcrp and P-gp respectively in perfused rat livers. The values for the hepatic extraction ratio had no statistical significance, whereas cumulative biliary excretion rates of cefditoren were significantly reduced to 43.8% and 79.5% over 25 min in the perfused probenecid and novobiocin rats, respectively. We further investigated the effects of cefditoren on the expression of hepatic transporters by RT-PCR and Western blot after oral administration of cefditoren one week. The expression levels of Mrp2, Bcrp, Oat2 mRNA were markedly increased, while P-gp and Oct1 mRNA were decreased. In concordance with RT-PCR results, Mrp2 expression level increased by Western blotting. These results indicate that Mrp2 and Bcrp may be involved in the biliary excretion of cefditoren. Cefditoren can up-regulate the expression levels of Mrp2, Bcrp and Oat2, and down-regulate P-gp and Oct1 mRNA expression. These results provide important data for drug-drug interactions.

PEGylation of osteoprotegerin/osteoclastogenesis inhibitory factor (OPG/OCIF) results in decreased uptake into rats and human liver

OBJECTIVES

Our aim was to investigate the effect of PEGylation on the uptake of osteoprotegerin/osteoclastogenesis inhibitory factor (OPG/OCIF) into rat liver, kidney and spleen, and human liver.

METHODS

Copolymer of polyethyleneglycol allylmethylether and maleamic acid sodium salt with OCIF (poly(PEG)-OCIF) (0.5 mg/kg) was administered to rats and the concentrations of poly(PEG)-OCIF in the liver, kidney and spleen at 15 min after administration were measured by ELISA. For human liver uptake, the liver perfusion of OCIF and (3)H-labelled poly(PEG)-OCIF was conducted using fresh human liver block.

KEY FINDINGS

The tissue uptake of poly(PEG)-OCIF in rats was significantly lower compared with that of OCIF. In fresh human liver perfusion, (3)H-poly(PEG)-OCIF was rarely taken up into the liver. On the other hand, more than 50% of the perfused OCIF was taken up.

CONCLUSIONS

PEGylation of OCIF using poly(PEG) dramatically suppressed the uptake of OCIF into human liver as well as into rat liver and could be a promising approach for improving the pharmacokinetic and pharmacological effects of OCIF in the clinical setting.

Therapeutic potential of transdifferentiated cells

Cell therapy means treating diseases with the body's own cells. The ability to produce differentiated cell types at will offers a compelling new approach to cell therapy and therefore for the treatment and cure of a plethora of clinical conditions, including diabetes, Parkinson's disease and cardiovascular disease. Until recently, it was thought that differentiated cells could only be produced from embryonic or adult stem cells. Although the results from stem cell studies have been encouraging, perhaps the most startling findings have been the recent observations that differentiated cell types can transdifferentiate (or convert) into a completely different phenotype. Harnessing transdifferentiated cells as a therapeutic modality will complement the use of embryonic and adult stem cells in the treatment of degenerative disorders. In this review, we will examine some examples of transdifferentiation, describe the theoretical and practical issues involved in transdifferentiation research and comment on the long-term therapeutic possibilities.

Animal models of liver regeneration

Owing to its powers of regeneration, the liver is capable of in vivo "tissue engineering" which enables complete restoration of liver architecture and re-establishment of the specific functions of the liver after various types of liver injury. Our current understanding of liver regeneration forms the basis of modern liver surgery and is now taken into consideration in the treatment of many liver diseases, in liver transplantation and hepatic tissue engineering. These advances have been achieved primarily by studies of liver regeneration in animal models after partial hepatectomy, attention being focused on the general mechanisms of cell proliferation. In recent years, however, toxin-induced models of liver regeneration have assumed growing importance, and by studying the interaction between cell damage and cell regeneration have made possible an investigation of liver regeneration of greater clinical relevance. However, the mechanisms of liver regeneration in patients with pre-existing chronic liver damage such as liver cirrhosis are still largely unexplored. This review examines and critically appraises the various approaches to the study of liver regeneration in animal models, including both surgical and pharmacological approaches.

Up-regulation of hepatocyte growth factor caused by an over-expression of transforming growth factor beta, in the rat model of fulminant hepatic failure

BACKGROUND

The role of transforming growth factor beta (TGF-beta), a potent regulator of cellular growth, was investigated in the rat model of fulminant hepatic failure (FHF).

MATERIALS AND METHODS

The rat FHF model was created by a combination of a 68% partial hepatectomy (PH) and 7% of necrosis (each n = 25 in Groups 1, 2 and 3). Adenovirus mediated gene transfer of mature human TGF-beta1 gene was performed by the systemic injection of AxCAhTGFb1 (1 x 10(9) pfu) in Group 1, 3 days before FHF. In control Groups 2 and 3, recombinant lacZ adenovirus (AxCAlacZ, Group 2) and normal saline (1 ml, Group 3) were used, instead of AxCAhTGFb1.

RESULTS

An excessive expression of TGF-beta1 in Group 1 resulted in an inhibition of hepatocyte proliferation (24-48 h after FHF) and gaining of liver weight (24-48 h), increased expression of HGF in liver tissue (24 h), and decreased expression of TGF-alpha (24 h), compared to those in control Groups 2 and 3. Serum IL-6 levels were also elevated by a TGF-beta1 over-expression at 24 hrs after FHF in Group 1.

CONCLUSIONS

The forced expression of TGF-beta1 in the FHF liver yields both a secondary increase of HGF production and a suppression of liver regeneration, which might explain the mechanism of increased serum HGF observed in a clinical FHF. TGF-beta1 is thus thought to have an important role in inhibiting liver regeneration after FHF.

Hepatocyte growth factor may act as an early therapeutic predictor in pneumonia

High serum levels of hepatocyte growth factor (HGF) may reflect the regenerative effect and enhanced local and systemic production of this cytokine after organ injuries. The possibility of using serial serum HGF values in order to predict the results of therapy for pneumonia was investigated in this study. In a prospective multicenter study we investigated the serum levels of HGF and CRP before and within 48 h after treatment in 70 patients with pneumonia. Serum levels of HGF before treatment were significantly higher than the HGF levels of a normal population (p < 0.0001). Within 48 h serum HGF levels had decreased significantly in those patients who ultimately responded to the initial antibiotic therapy (p < 0.0001). Serum HGF levels at 48 h were unchanged or increased in cases in whom the initial therapy was ineffective and had to be changed. CRP and HGF levels were significantly correlated. Using multivariate logistic regression analysis it was found that individual changes in acute serum HGF levels and serum HGF levels obtained within 48 h could predict the results of therapy at least as significantly (p < 0.003) as CRP (p = 0.05), although CRP levels were known and used by the physician to decide whether or not to change the initial therapy. We conclude that serial control of serum HGF levels can be used as an early indicator to predict the results of therapy during treatment of pneumonia.

CCl4-induced acute liver injury in mice is inhibited by hepatocyte growth factor overexpression but stimulated by NK2 overexpression

Hepatocyte growth factor (HGF) inhibits acute liver injury. NK2 acts as an antagonist to HGF in vitro, but its in vivo function has reached no consensus conclusions. We have investigated in vivo effects of HGF and NK2 on CCl4-induced acute liver injury. Elevation of the serum alanine aminotransferase level and extension of centrilobular necrosis were inhibited in HGF transgenic mice but were promoted in NK2 transgenic mice. Hepatocyte proliferation after liver injury was not inhibited in NK2 transgenic mice. Thus, this study indicates that HGF inhibits liver injury, and NK2 antagonizes HGF on liver injury, however, NK2 may not antagonize HGF on hepatocyte proliferation.

Hepatocyte growth factor and 24-hour ambulatory blood pressure monitoring

In recent years, many growth factors and cytokines have been shown to be related to arteriosclerosis, and hepatocyte growth factor (HGF) has been reported to be associated with hypertension. In the present study, we investigated the relationship between HGF and hypertension by measuring the serum HGF concentration and performing 24-h ambulatory blood pressure monitoring (ABPM) in 47 randomly selected male and female subjects who underwent a medical examination for cardiovascular disease. The results were as follows. 1) The mean serum HGF concentration in the subjects was 0.35+/-0.14 ng/ml. 2) The serum HGF concentration was positively correlated with both the nighttime systolic and diastolic blood pressures (r=0.42, p<0.05 and r=0.47, p<0.01, respectively). 3) No correlation was found between serum HGF concentration and daytime systolic or diastolic blood pressure. 4) When subjects were divided into two groups based on the difference between daytime and nighttime systolic blood pressure, i.e., a group in which the difference was less than 10 mmHg and a group in which the difference was 10 mmHg or more, the HGF concentration was significantly higher in the former group (0.39+/-0.14 vs. 0.30+/-0.12 ng/ml, p<0.05); similarly, when subjects were divided into a group in which the difference between daytime and nighttime diastolic blood pressure was 5 mmHg and a group in which the difference was 5 mmHg or more, the HGF concentration was significantly higher in the former group (0.42+/-0.15 vs. 0.31+/-0.12 ng/ml, p<0.05). The results indicated that there is a relationship between blood pressure measured by ABPM and serum HGF concentration, and that this relationship might be an index of damage to blood vessels in patients with hypertension.

Plasma human hepatocyte growth factor concentrations in patients with biliary obstruction

BACKGROUND

It has been suggested that human hepatocyte growth factor (hHGF) maintains the growth and viability of hepatocytes and biliary epithelial cells. The purpose of this study was to determine plasma hHGF concentrations in patients with obstructive jaundice and to correlate these findings with clinical outcome.

METHODS

The study included 22 patients who had biliary obstruction and underwent percutaneous transhepatic biliary drainage. The plasma concentrations of hHGF, standard liver function tests, daily bile flow and the half-life of serum total bilirubin were measured following the drainage.

RESULTS

Plasma hHGF concentrations were significantly higher in patients with biliary obstruction compared with a control group (P<0.01). The plasma hHGF concentrations correlated with white cell count, prothrombin time and bilirubin half-life (P<0.05), but not with the values from other liver function tests. Seven patients who died within 3 months after biliary drainage had significantly higher concentrations of plasma hHGF than the 15 patients who survived for at least 3 months (P<0.05). The patients who experienced a poor outcome also had lower bile flows and prolonged bilirubin half-lives compared with the survivors (P<0.05). The plasma hHGF concentrations decreased significantly after biliary drainage in the survivors (P<0.01), but not in the patients with a poor outcome.

CONCLUSIONS

These results suggest that systemic inflammation and the hepatic dysfunction caused by obstructive jaundice cause an increase in the plasma concentrations of hHGF. In addition, the plasma concentrations of hHGF may be a predictor of poor outcome in jaundiced patients.

Hepatocyte growth factor prevents endotoxin-induced lethal hepatic failure in mice

Sepsis and endotoxemia are involved in the development of fulminant hepatic failure, the prognosis of which is extremely poor and the mortality is high, with no available effective therapy. Here, we report that hepatocyte growth factor (HGF) exerts potent antiapoptotic effects in vivo and effectively prevents endotoxin-induced fulminant hepatic failure in mice. The animals were intraperitoneally injected three times with 120 micrograms human recombinant HGF or saline 6 hours and 30 minutes before and 3 hours after an intraperitoneal injection of lipopolysaccharide (LPS) and D-galactosamine (GalN). Administration of LPS + GalN, without HGF, rapidly led to massive hepatocyte apoptosis and severe liver injury, and all mice died of hepatic failure within 8 hours. In contrast, administration of human recombinant HGF strongly suppressed extensive progress of hepatocyte apoptosis and the liver injury induced by LPS + GalN, and 75% of the HGF-treated mice survived. Moreover, HGF strongly induced Bcl-xL expression and blocked apoptotic signal transduction upstream of CPP32 (caspase-3) in the liver, thereby leading to inhibition of massive hepatocyte apoptosis. We suggest that HGF may well have the potential to prevent fulminant hepatic failure, at least through its potent antiapoptotic action.

Expression of hepatocyte growth factor (HGF) and HGF receptor (c-met) proteins in liver diseases: an immunohistochemical study

BACKGROUND

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes in vivo as well as in vitro. Serum levels of HGF vary in liver diseases, reflecting liver damage and dysfunction. However there are no studies reporting expression of HGF and HGF receptor (c-met protein) simultaneously in various liver diseases.

METHODS

To clarify the clinical significance of HGF/c-met protein expression in liver diseases, liver tissues from 62 patients consisting of 7 with acute hepatitis (AH), 20 with chronic hepatitis (CH), 9 with liver cirrhosis (LC) and 26 with hepatocellular carcinoma (HCC) were immunohistochemically examined.

RESULTS

Intense staining of HGF was observed in patients from AH, CH and LC, although no immunoreactivity was seen in HCC. The expression of c-met protein was higher in patients with HCC and AH than in those with CH (p < 0.05). A correlation of immunoreactivity between HGF and c-met protein was not observed expect in patients with LC (p < 0.01). The extent of c-met expression had no correlation with differentiation of HCC, tumour size, presence of portal invasion, or serum AFP levels.

CONCLUSION

The results of the present study suggest that HGF plays an important role in human liver diseases, mostly in a manner independent of c-met protein expression.

Ligand-induced downregulation of receptor-mediated clearance of hepatocyte growth factor in rats

The change in tissue uptake clearance of 125I-labeled hepatocyte growth factor (HGF) after an intravenous injection of an excess (120 micrograms/kg) of unlabeled HGF was examined in rats. The heparin-washable component of the hepatic uptake clearance of 125I-HGF was only slightly changed, whereas the heparin-resistant component was significantly reduced 30 min after injection of excess HGF, followed by gradual recovery with a half-life of 3.2 h. Because the former clearance mainly represents 125I-HGF association with heparan sulfate proteoglycan on the cell surface and/or extracellular matrix, whereas the latter includes relatively specific clearance, such as receptor-mediated endocytosis, this result suggests that injection of excess HGF selectively causes downregulation of receptor-mediated HGF clearance in the liver. Downregulation could also be observed for HGF receptor density in isolated liver plasma membrane, assessed by Western blot analysis by means of anti-receptor antibody, 30 min after injection of excess unlabeled HGF, supporting the hypothesis that the overall elimination of HGF from the systemic circulation can be affected by a change in HGF receptor density on the liver cell surface.

Protamine enhances the proliferative activity of hepatocyte growth factor in rats

The effect of protamine on the proliferative activity of hepatocyte growth factor (HGF) was examined in alpha-naphthyl isothiocyanate-intoxicated rats. Protamine pre-injection increased the hepatocyte labeling index induced by HGF four- to fivefold. A similar effect was also observed in partially hepatectomized rats. Because a cell surface heparin-like substance can bind to HGF and protamine has an affinity for heparin, protamine may affect HGF pharmacokinetics. In fact, protamine injection caused a transient increase in plasma HGF concentrations after administration of HGF and, in vitro, protamine eluted HGF prebound to heparin-Sepharose. Protamine also reduced the plasma clearance of HGF and increased 2.5-fold the exposure of hepatocytes to HGF in vivo. The enhancing effect of protamine on the mitogenic response of hepatocytes to HGF was also observed in vitro (approximately 2-fold after protamine pretreatment compared with HGF alone), suggesting that the enhancing effect of protamine on HGF-induced liver regeneration results from dual effects exerted by protamine 1) lowering the overall elimination of HGF and 2) directly stimulating hepatocyte mitosis induced by HGF.

Existence of two nonlinear elimination mechanisms for hepatocyte growth factor in rats

Nonlinearity in the overall elimination of hepatocyte growth factor (HGF) was examined in rats. After intravenous administration, the plasma clearance (CLplasma) of HGF exhibited a dose-dependent biphasic reduction with high- and low-affinity components. If we consider our previous finding that both receptor-mediated endocytosis (RME) and a low-affinity uptake mechanism, probably mediated by heparan sulfate proteoglycan (HSPG), in the liver are major HGF clearance mechanisms, it may be that saturation of CLplasma at lower and higher doses represents saturation of RME and HSPG-mediated uptake, respectively. At an HGF dose (1.46 nmol/kg), which completely saturates the high-affinity component, CLplasma was almost completely reduced when HGF was premixed with heparin. However, CLplasma was reduced by heparin to, at most, one-fifth that after HGF alone in a dose near the linear range (3.66 pmol/kg). Saturation of CLplasma for HGF premixed with heparin was monophasic and nonlinear only at the lowest HGF doses. In vitro, high-affinity binding of [35S]heparin to HGF was found, showing that one HGF molecule binds to the penta- or hexasaccharide unit. Because mitogenic activity of HGF has been reported in the presence of heparin, these results suggest that heparin mainly inhibits low-affinity HGF uptake by complexing with HGF, whereas its effect on RME is relatively minor.

Plasma hepatocyte growth factor levels are increased in systemic inflammatory response syndrome

Interleukin-1 (IL-1), a cytokine released from macrophages by endotoxin stimulation, has been shown to upregulate the genetic expression of the hepatocyte growth factor (HGF). The present study was conducted to determine whether plasma HGF is increased in patients with systemic inflammatory response syndrome (SIRS). The plasma levels of HGF, endotoxin, and beta-glucan were measured in 41 surgical patients without hepatic diseases, 18 of whom had been diagnosed with sepsis, and 33, with nonseptic SIRS. The plasma HGF was found to be significantly increased in the 18 patients with sepsis, at 0.69 +/- 0.47 ng/ml (mean +/- SD), and in the 23 patients with nonseptic SIRS, at 0.49 +/- 0.37 ng/ml, compared to values in 40 normal controls, at 0.10 +/- 0.03 ng/ml (P < 0.001). No significant correlations were observed between the plasma levels of HGF and endotoxin (r = 0.02) or beta-glucan (r = -0.05) in any of the patients; however, plasma HGF was significantly correlated with the WBC count (r = 0.34, P < 0.05) and with total bilirubin (r = 0.45, P < 0.01). Plasma HGF was also strongly correlated with alanine transaminase (ALT) in 8 patients with ALT levels higher than 50 U/l (r = 0.70), but there was no such correlation in 33 patients with ALT levels of 50 U/l or less (r = 0.30). Thus, although the clinicopathologic significance of HGF is not well understood, the present findings indicate that plasma HGF increases in response to infection or inflammation.

Contribution of parenchymal and non-parenchymal liver cells to the clearance of hepatocyte growth factor from the circulation in rats

PURPOSE

The distribution of 125I-hepatocyte growth factor (HGF) to either liver parenchymal cells (PC) or non-parenchymal cells (NPC) was investigated in rats.

METHODS

After injection of a trace amount of 125I-HGF, the distribution of radioactivity determined by microautoradiography closely resembled that of 125I-epidermal growth factor which distributes mainly to PC.

RESULTS

The uptake clearance of 125I-HGF estimated by determining the radioactivity of isolated liver cells was three times higher for PC than for NPC. This suggests that HGF distributes mainly to PC at relatively low doses. On the other hand, the uptake clearance by PC fell on coadministering an excess (80 micrograms/kg) of unlabeled HGF, while no change was observed for NPC, indicating that a saturable process for the hepatic handling of HGF exists only in PC where the HGF receptor is expressed.

CONCLUSIONS

At such a dose the uptake clearance was comparable for both PC and NPC showing that HGF distributes to both cell types although NPC have few HGF receptors. Since the distribution to NPC was relatively non-specific and heparin-sensitive, it may be that heparin-like substances, which are believed to exist on PC and/or the extracellular matrix, also exist on NPC.

Hepatocyte growth factor--pleiotropic cytokine produced by human leukemia cells

Hepatocyte growth factor (HGF) was identified, purified and molecularly cloned as a potent mitogen for mature rat hepatocytes in primary culture. It is one of the largest cytokines and is composed of disulfide-linked subunits of approximately 60 (heavy chain) and 35 kilodaltons (light chain). Recent observations revealed that HGF is mitogenic to various epithelial cells other than hepatocytes and to endothelial cells, and that it also acts as a motogen, morphogen and tumor-suppressor as well as a mitogen. These various biological activities of HGF are presumably transduced through the same receptor, c-Met, which is a member of the tyrosine kinase receptor family. Although it shows multiple biological activities on cells in culture, HGF is most likely the physiological hepatotrophic factor which triggers liver regeneration. It may also function as a renotrophic and pulmotrophic factor after tissue injury. HGF production in the liver, kidney and lung increases after injury to these organs. An elevated HGF level may act as an inducer of compensatory DNA synthesis. The regulation of HGF production is, therefore, important for the control of organ regeneration. HGF is produced mainly by mesenchymal cells such as fibroblasts and vascular smooth muscle cells. Various types of human leukemia cells also secrete HGF both in vitro and in vivo. Some biological activities of HGF on hematopoietic cells, including co-mitogenic activity on myeloid leukemia cell lines, were recently demonstrated. HGF gene expression and the protein production in leukemia and fibroblast cells are modulated by various cytokines and hormones. Those modulators may indirectly affect organ regeneration and other biological processes by controlling HGF production.

Sulfated oligosaccharides promote hepatocyte growth factor association and govern its mitogenic activity

Hepatocyte growth factor (HGF) is a potent mitogen, motogen, and morphogen for various epithelial cell types. The pleiotropic effects of HGF are mediated by its binding to a specific high affinity receptor, c-Met. In addition, HGF binds to heparan sulfate proteoglycans on cell surfaces and within the extracellular matrix. Incubation of HGF with 0.1, 1.0, and 10 micrograms/ml of heparin, heparan sulfate, or dextran sulfate resulted in a concentration-dependent increase in mitogenic potency in a primary rat hepatocyte bioassay, whereas sodium sulfate or fucoidan did not. Although co-incubation of HGF with sulfated compounds that enhanced HGF-dependent mitogenesis did not alter the binding isotherm of HGF for the c-Met receptor in a solid phase assay, an increase in autophosphorylation of the c-Met receptor in intact A549 cells was observed upon their addition. A series of chemically sulfated malto-oligosaccharides varying in unit size and charge was tested in the bioassay in order to provide additional insights into the nature of the HGF-heparin interaction. While sulfated di-, tri-, tetra-, and pentasaccharides did not significantly potentiate HGF-dependent mitogenesis, larger oligosaccharides such as the sulfated hexa-, hepta-, or a sulfated oligosaccharide mixture containing decasaccharides resulted in an approximate 2-, 4-, and 7-fold enhancement, respectively. We observed a correlation between the sulfated oligosaccharide preparations that enhanced mitogenic potency and those that promoted HGF oligomerization in vitro, as measured by gel filtration and analytical ultracentrifugation. These findings indicate that heparin-like molecules can stabilize HGF oligomers, which may facilitate c-Met receptor dimerization and activation.

Serum hepatocyte growth factor levels in liver diseases: clinical implications

Although recent studies have shown that hepatocyte growth factor (HGF) is a potent mitogen in vivo, the significance of serum HGF in liver diseases remains unclear. To clarify clinical significance of serum HGF in liver diseases, serum HGF was measured in 127 patients with liver diseases and in 200 healthy individuals, using a highly sensitive immunoradiometric assay (IRMA). This assay is specific for HGF and is sensitive enough to detect 0.1 ng/mL of HGF. Mean values for serum HGF in acute hepatitis (AH), chronic hepatitis (CH), liver cirrhosis (LC), hepatocellular carcinoma (HCC), primary biliary cirrhosis (PBC), fulminant hepatic failure (FHF), and normal controls were 0.45, 0.40, 1.05, 1.06, 0.44, 16.40, and 0.27 ng/mL, respectively. Serum HGF levels in these diseases were significantly increased compared with those in the controls (P < .001), and exhibited a positive correlation with total bilirubin, indocyanine green (ICG) test (R15), asparate aminotransferase (AST), and a negative correlation with albumin and prothrombin time (P < .001). Cirrhotic patients with modified Child class C had higher levels of serum HGF than those graded as modified Child class A or B (P < .001). In CH, serum HGF levels were significantly related to the histological activity index (HAI) score (P < .002). Seven patients with HCC who underwent transcatheter arterial embolization (TAE) exhibited a gradual increase in serum HGF levels up to day 4 after treatment; these higher levels were maintained until day 7, although AST reached a peak on day 2 and then decreased gradually.(ABSTRACT TRUNCATED AT 250 WORDS)