Continuous hepatocyte growth factor supply prevents lipopolysaccharide-induced liver injury in rats

Novel indirect co-culture of immortalised hepatocytes with monocyte derived macrophages is characterised by pro-inflammatory cytokine networks

The liver is composed of different cell populations. Interactions of different cell populations can be investigated by a newly established indirect co-culture system consisting of immortalised primary human hepatocytes and human monocyte derived macrophages (MDMs). Using the time-dependent cytokine secretion of the co-cultures and single cultures, correlation networks (including the cytokines G-CSF, CCL3, MCP-1, CCL20, FGF, TGF-β1, GM-CSF, IL-8 IL-6, IL-1β, and IL-18) were generated and the correlations were validated by application of IL-8 and TNF-α-neutralising antibodies. The data reveal that IL-8 is crucial for the interaction between hepatocytes and macrophages in vitro. In addition, transcriptome analyses showed that a change in the ratio between macrophages and hepatocytes may trigger pro-inflammatory signalling pathways of the acute phase response and the complement system (release of, e.g., certain cyto- and chemokines). Using diclofenac and LPS showed that the release of cytokines is increasing with higher ratios of MDMs. Altogether, we could demonstrate that the current co-culture system is better suited to mirror the in vivo situation when compared to previously established co-culture systems composed of HepG2 and differentiated THP-1 cells. Further, our data reveal that the cytokine IL-8 is crucial for the interaction between hepatocytes and macrophages in vitro.

Yi Guan Jian decoction may enhance hepatic differentiation of bone marrow‑derived mesenchymal stem cells via SDF‑1 in vitro

A previous study reported that Yi Guan Jian (YGJ) may increase the proliferation and differentiation of hepatic oval cells in a rat liver cirrhosis model. The aim of the present study was to investigate the effect and mechanism of action of YGJ on inducing hepatic differentiation in bone marrow-derived mesenchymal stem cells (BM-MSCs) via stromal-cell derived factor-1 (SDF-1). Murine BM-MSCs were isolated with whole bone marrow adherence, then identified by immunocytochemical staining and flow cytometry. Passage 2 cells were divided into 8 groups and their differentiation was induced by cell factors added to the medium, including hepatocyte growth factor (HGF), SDF-1 and YGJ. Each of the cell factors was used alone and any two or three of them were combined to establish different cell microenvironments in the different treatment groups. Albumin (ALB) was selected as a hepatocellular marker and cytokeratin-18 (CK-18) as a cholangiocellular marker. The protein and mRNA expression levels of ALB and CK-18 were used to determine the differentiation of BM-MSCs using immunocytochemical staining, western blotting and reverse transcription-quantitative polymerase chain reaction on days 7, 14, 21 and 28 during induction. The relative expression levels of ALB and CK-18 resulted in time-dependent increases in the groups supplemented only with HGF, SDF-1 or YGJ. Combination treatment of any two HGF, SDF-1 and YGJ led to a higher expression of ALB and CK-18 compared with only one cell factor treatment. Additionally, when all three were used in a combined treatment the expression levels of ALB and CK-18 occurred at an earlier time and was higher overall. Therefore, the present study suggested that YGJ had an effect on inducing hepatic differentiation in BM-MSCs via SDF-1 and may act in a synergistic manner with HGF and SDF-1.

Is Serum Angiotensin-Converting Enzyme Level Useful For Determining Necroinflammatory Activity In Chronic Hepatitis B Infection?

AIM

The purpose of this study was to investigate the relationship between the findings from liver biopsy and the serum angiotensin-converting enzyme (ACE) level to determine whether ACE might serve as a potential noninvasive sign of necroinflammatory activity in patients with Chronic Hepatitis B (CHB) infection.

METHODS

A total of 54 CHB patients referred for liver biopsy were enrolled in the study. Serum ACE levels were determined photometrically with a kinetic test.

RESULTS

The aspartate aminotransferase (AST), alanine aminotransferase (ALT), hepatitis B virus-deoxyribonucleic acid (HBV-DNA), histological activity index (HAI), and white blood cell counts were higher in patients with severe fibrosis, while albumin levels were low. The serum ACE levels showed a statistically significant correlation with HBV-DNA, HAI score, and ALT-AST levels.

DISCUSSION

In this study, a statistically significant relation between serum ACE levels and HAI scores was observed. This represents the first analysis to compare necroinflammation of the liver and serum ACE levels. There may be some explanations that the suppression of hepatocyte growth factor (HGF) by Angiotensin II and increased inflammatory damage might be a reason for the correlation between HAI and ACE. Serum ACE levels, HBV-DNA levels, and serum transaminase levels might be used together as noninvasive markers for the prediction of necroinflammation in CHB patients.

Effects of platelet-rich plasma and triamcinolone acetonide on interleukin-1ß-stimulated human rotator cuff-derived cells

Objectives

Triamcinolone acetonide (TA) is widely used for the treatment of rotator cuff injury because of its anti-inflammatory properties. However, TA can also produce deleterious effects such as tendon degeneration or rupture. These harmful effects could be prevented by the addition of platelet-rich plasma (PRP), however, the anti-inflammatory and anti-degenerative effects of the combined use of TA and PRP have not yet been made clear. The objective of this study was to determine how the combination of TA and PRP might influence the inflammation and degeneration of the rotator cuff by examining rotator cuff-derived cells induced by interleukin (IL)-1ß.

Methods

Rotator cuff-derived cells were seeded under inflammatory stimulation conditions (with serum-free medium with 1 ng/ml IL-1ß for three hours), and then cultured in different media: serum-free (control group), serum-free + TA (0.1mg/ml) (TA group), serum-free + 10% PRP (PRP group), and serum-free + TA (0.1mg/ml) + 10% PRP (TA+PRP group). Cell morphology, cell viability, and expression of inflammatory and degenerative mediators were assessed.

Results

Exposure to TA significantly decreased cell viability and changed the cell morphology; these effects were prevented by the simultaneous administration of PRP. Compared with the control group, expression levels of inflammatory genes and reactive oxygen species production were reduced in the TA, PRP, and TA+PRP groups. PRP significantly decreased the expression levels of degenerative marker genes.

Conclusions

The combination of TA plus PRP exerts anti-inflammatory and anti-degenerative effects on rotator cuff-derived cells stimulated by IL-1ß. This combination has the potential to relieve the symptoms of rotator cuff injury.

Cite this article: T. Muto, T. Kokubu, Y. Mifune, A. Inui, R. Sakata, Y. Harada, F. Takase, M. Kurosaka. Effects of platelet-rich plasma and triamcinolone acetonide on interleukin-1ß-stimulated human rotator cuff-derived cells. Bone Joint Res 2016;5:602–609. DOI: 10.1302/2046-3758.512.2000582.

Novel role for endogenous hepatocyte growth factor in the pathogenesis of intracranial aneurysms

Inflammation plays a key role in formation and rupture of intracranial aneurysms. Because hepatocyte growth factor (HGF) protects against vascular inflammation, we sought to assess the role of endogenous HGF in the pathogenesis of intracranial aneurysms. Circulating HGF concentrations in blood samples drawn from the lumen of human intracranial aneurysms or femoral arteries were compared in 16 patients. Tissue from superficial temporal arteries and ruptured or unruptured intracranial aneurysms collected from patients undergoing clipping (n=10) were immunostained with antibodies to HGF and its receptor c-Met. Intracranial aneurysms were induced in mice treated with PF-04217903 (a c-Met antagonist) or vehicle. Expression of inflammatory molecules was also measured in cultured human endothelial, smooth muscle cells and monocytes treated with lipopolysaccharides in presence or absence of HGF and PF-04217903. We found that HGF concentrations were significantly higher in blood collected from human intracranial aneurysms (1076±656 pg/mL) than in femoral arteries (196±436 pg/mL; P<0.001). HGF and c-Met were detected by immunostaining in superficial temporal arteries and in both ruptured and unruptured human intracranial aneurysms. A c-Met antagonist did not alter the formation of intracranial aneurysms (P>0.05), but significantly increased the prevalence of subarachnoid hemorrhage and decreased survival in mice (P<0.05). HGF attenuated expression of vascular cell adhesion molecule-1 (P<0.05) and E-Selectin (P<0.05) in human aortic endothelial cells. In conclusion, plasma HGF concentrations are elevated in intracranial aneurysms. HGF and c-Met are expressed in superficial temporal arteries and in intracranial aneurysms. HGF signaling through c-Met may decrease inflammation in endothelial cells and protect against intracranial aneurysm rupture.

Synthesis of IL-6 by hepatocytes is a normal response to common hepatic stimuli

Exogenous interleukin 6 (IL-6), synthesized at the initiation of the acute phase response, is considered responsible for signaling hepatocytes to produce acute phase proteins. It is widely posited that IL-6 is either delivered to the liver in an endocrine fashion from immune cells at the site of injury, or alternatively, in a paracrine manner by hepatic immune cells within the liver. A recent publication showed there was a muted IL-6 response in lipopolysaccharide (LPS)-injured mice when nuclear NFκB was specifically inactivated in the hepatocytes. This indicates hepatocellular signaling is also involved in regulating the acute phase production of IL-6. Herein, we present extensive in vitro and in vivo evidence that normal hepatocytes are directly induced to synthesize IL-6 mRNAs and protein by challenge with LPS, a bacterial hepatotoxin, and by HGF, an important regulator of hepatic homeostasis. As the IL-6 receptor is found on the hepatocyte, these results reveal that induction of the acute phase response can be regulated in an autocrine as well as endocrine/paracrine fashion. Further, herein we provide data indicating that following partial hepatectomy (PHx), HGF differentially regulates IL-6 production in hepatocytes (induces) versus immune cells (suppresses), signifying disparate regulation of the cell sources involved in IL-6 production is a biologically relevant mechanism that has previously been overlooked. These findings have wide ranging ramifications regarding how we currently interpret a variety of in vivo and in vitro biological models involving elements of IL-6 signaling and the hepatic acute phase response.

Quantitative proteomic analysis of hepatocyte-secreted extracellular vesicles reveals candidate markers for liver toxicity

Extracellular vesicles have created great interest as possible source of biomarkers for different biological processes and diseases. Although the biological function of these vesicles is not fully understood, it is clear that they participate in the removal of unnecessary cellular material and act as carriers of various macromolecules and signals between the cells. In this report, we analyzed the proteome of extracellular vesicles secreted by primary hepatocytes. We used one- and two-dimensional liquid chromatography combined with data-independent mass spectrometry. Employing label-free quantitative proteomics, we detected significant changes in vesicle protein expression levels in this in vitro model after exposure to well-known liver toxins (galactosamine and Escherichia coli-derived lipopolysaccharide). The results allowed us to identify candidate markers for liver injury. We validated a number of these markers in vivo, providing the basis for the development of novel methods to evaluate drug toxicity. This report strongly supports the application of proteomics in the study of extracellular vesicles released by well-controlled in vitro cellular systems. Analysis of such systems should help to identify specific markers for various biological processes and pathological conditions.

BIOLOGICAL SIGNIFICANCE

Identification of low invasive candidate marker for hepatotoxicity. Support to apply proteomics in the study of extracellular vesicles released by well-controlled in vitro cellular systems to identify low invasive markers for diseases.

HGF mediates the anti-inflammatory effects of PRP on injured tendons

Platelet-rich plasma (PRP) containing hepatocyte growth factor (HGF) and other growth factors are widely used in orthopaedic/sports medicine to repair injured tendons. While PRP treatment is reported to decrease pain in patients with tendon injury, the mechanism of this effect is not clear. Tendon pain is often associated with tendon inflammation, and HGF is known to protect tissues from inflammatory damages. Therefore, we hypothesized that HGF in PRP causes the anti-inflammatory effects. To test this hypothesis, we performed in vitro experiments on rabbit tendon cells and in vivo experiments on a mouse Achilles tendon injury model. We found that addition of PRP or HGF decreased gene expression of COX-1, COX-2, and mPGES-1, induced by the treatment of tendon cells in vitro with IL-1β. Further, the treatment of tendon cell cultures with HGF antibodies reduced the suppressive effects of PRP or HGF on IL-1β-induced COX-1, COX-2, and mPGES-1 gene expressions. Treatment with PRP or HGF almost completely blocked the cellular production of PGE2 and the expression of COX proteins. Finally, injection of PRP or HGF into wounded mouse Achilles tendons in vivo decreased PGE2 production in the tendinous tissues. Injection of platelet-poor plasma (PPP) however, did not reduce PGE2 levels in the wounded tendons, but the injection of HGF antibody inhibited the effects of PRP and HGF. Further, injection of PRP or HGF also decreased COX-1 and COX-2 proteins. These results indicate that PRP exerts anti-inflammatory effects on injured tendons through HGF. This study provides basic scientific evidence to support the use of PRP to treat injured tendons because PRP can reduce inflammation and thereby reduce the associated pain caused by high levels of PGE2.

Improvement of sepsis by hepatocyte growth factor, an anti-inflammatory regulator: emerging insights and therapeutic potential

Sepsis-induced multiple organ failure (MOF) is the most frequent lethal disease in intensive care units. Thus, it is important to elucidate the self-defensive mechanisms of sepsis-induced MOF. Hepatocyte growth factor (HGF) is now recognized as an organotrophic factor, which is essential for organogenesis during embryonic growth and regeneration in adulthood. HGF production is enhanced in response to infectious challenges, but the increase in endogenous HGF levels is transient and insufficient, with a time lag between tissue injuries and HGF upregulation, during progression of septic MOF. Thus, administration of active-formed HGF might be a new candidate for therapeutic development of MOF. HGF has an ability to target endotoxin-challenged macrophages and inhibits the upregulation of inflammatory cytokines through nuclear factor-κB-inactivated mechanisms. HGF also targets the endothelium and epithelium of various organs to suppress local inflammation, coagulation, and apoptotic death. This paper summarizes the novel mechanisms of HGF for attenuating sepsis-related pathological conditions with a focus on sepsis-induced MOF.

Gene therapy for liver regeneration: experimental studies and prospects for clinical trials

The liver is an exceptional organ, not only because of its unique anatomical and physiological characteristics, but also because of its unlimited regenerative capacity. Unfolding of the molecular mechanisms that govern liver regeneration has allowed researchers to exploit them to augment liver regeneration. Dramatic progress in the field, however, was made by the introduction of the powerful tool of gene therapy. Transfer of genetic materials, such as hepatocyte growth factor, using both viral and non-viral vectors has proved to be successful in augmenting liver regeneration in various animal models. For future clinical studies, ongoing research aims at eliminating toxicity of viral vectors and increasing transduction efficiency of non-viral vectors, which are the main drawbacks of these systems. Another goal of current research is to develop gene therapy that targets specific liver cells using receptors that are unique to and highly expressed by different liver cell types. The outcome of such investigations will, undoubtedly, pave the way for future successful clinical trials.

Low-dose simultaneous delivery of adenovirus encoding hepatocyte growth factor and vascular endothelial growth factor in dogs enhances liver proliferation without systemic growth factor elevation

BACKGROUND

Hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) gene transfer proved to enhance liver regeneration. However, elevation of their plasma levels may induce potentially serious distant effects such as tumorigenesis or proliferative retinopathy.

AIMS

This study was performed to examine whether simultaneous administration of low-dose adenovirus encoding HGF and VEGF genes in dogs will stimulate liver proliferation but without inducing liver toxicity or systemic elevation of HGF and VEGF levels.

METHODS

Adult dogs received an intravenous injection of low-dose adenoviral vectors encoding human HGF and VEGF (HGF/VEGF), beta-galactosidase (lacZ) or phosphate-buffered saline (PBS). Liver proliferation was measured using the proliferating cell nuclear antigen (PCNA) immunostaining labelling index. HGF and VEGF plasma concentrations and transaminases were repeatedly measured. Transgene expression was evaluated using reverse-transcription polymerase chain reaction.

RESULTS

Human HGF and VEGF expressions were detected only in the liver of HGF/VEGF dogs at day 2 after injection but declined at sacrifice (day 7). No expression was detected in the liver of the lacZ or PBS groups. Plasma levels of HGF and VEGF were not statistically different from those in the lacZ group (P=0.81, P=0.22 respectively). The PCNA labelling index was five-fold higher in the HGF/VEGF group compared with the lacZ group (P<0.01). No immunostaining was detected in the PBS group. Transaminases were only elevated (P<0.01) in the lacZ group compared with the other groups.

CONCLUSIONS

We showed that simultaneous administration of low-dose adenoviral vectors encoding human HGF and VEGF genes can induce transgene expression and liver proliferation without liver toxicity or systemic growth factor elevation.

Hepatocyte growth factor: a regenerative drug for acute hepatitis and liver cirrhosis

Liver cirrhosis is a major cause of morbidity worldwide and is characterized by the loss of hepatocytes with interstitial fibrosis. In this review, we discuss the potential uses of hepatocyte growth factor for treating hepatic diseases, focusing on the molecular mechanisms whereby hepatocyte growth factor reverses liver cirrhosis. Hepatic myofibroblasts play a central role in the development of liver cirrhosis, while myofibroblasts acquire c-Met. Using a rat model of liver cirrhosis, we recently delineated the direct effect of hepatocyte growth factor toward myofibroblasts: the induction of apoptotic cell death associated with matrix degradation, the inhibition of overproliferation and the suppression of transforming growth factor-beta1 production in myofibroblasts. Hepatocyte growth factor elicits mitogenic, anti-apoptotic and anti-inflammatory functions in hepatocytes, therefore contributing to reversing liver dysfunction. Considering the insufficient production of hepatocyte growth factor is responsible for the manifestation of chronic hepatitis, supplementation with or reinduction of hepatocyte growth factor represents a new strategy for attenuating intractable liver diseases.

Serum hyaluronate level for predicting subclinical liver dysfunction after hepatectomy

The serum hyaluronate (HA) level reflects sinusoidal endothelial cell function correlated with liver function. We have reviewed multiple liver function indicators from 37 patients who underwent hepatectomy for various liver diseases. The serum HA level was well correlated with the indocyanine green retention rate at 15 minutes (ICGR15), lectin-cholesterol (LCAT), hepatocyte growth factor (HGF), liver uptake ratio of technetium-99m galactosyl human serum albumin (99mTc-GSA) at 15 minutes (HH15), prealbumin, and hepatic uptake ratio of 99mTc-GSA at 15 minutes (LHL15). In addition, the model for end-stage liver disease (MELD) score at 7 days after operation was well correlated with serum HA, ICGR15, HH15, and LHL15. In patients who showed serum an HA level of = 100 ng/ml before hepatectomy, the MELD score had significantly deteriorated by 7 days after hepatectomy. Of the 20 patients who showed a serum HA level < 100 ng/ml before hepatectomy, 11 had high serum HA after hepatectomy. The bilirubin level 7 days after operation in this group was much higher than that for patients who maintained a serum HA level < 100 ng/ml after hepatectomy. In addition, the serum HGF level before hepatectomy in this group was significantly lower. We concluded that the serum HA level is a reliable indicator when evaluating liver function and predicting liver dysfunction after hepatectomy. Furthermore, patients with a significantly low HGF level who have a normal HA level are susceptible to liver dysfunction after hepatectomy.

Hepatocyte growth factor and c-Met expression in rat and human liver fibrosis

BACKGROUND

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes in vitro.

AIMS

Substitution of HGF was suggested for human liver disease on the basis of animal experiments. The cellular sources of HGF and its receptor, c-Met, in liver disease in vivo are not well defined.

METHODS

We characterised HGF and c-Met expression in normal and cirrhotic human livers and rat livers at various time points after CCl4 administration by in situ hybridisation and immunohistology. HGF transcripts were restricted to resting and activated stellate cells in rat and human liver.

RESULTS

In rat liver, HGF showed peak levels 6-12 h following acute intoxication, and remained increased after repeated CCl4 injury. HGF transcript levels were very low in normal human liver, but excessively raised in fibrosis/cirrhosis. In contrast, HGF immunoreactivity was found not only in perisinusoidal/periductular cells but also in cholangiocytes of proliferating ductules. c-Met RNA and protein was expressed in hepatocytes, cholangiocytes, and arteriolar endothelial cells.

CONCLUSIONS

The HGF-specific immunostaining of proliferating cholangioles in the absence of HGF RNA suggests c-Met-mediated uptake of HGF and paracrine stimulation of cholangiocellular proliferation. Mitogenic effects of HGF on hepatocytes may therefore be accompanied by undesired cholangiogenesis and angiogenesis limiting its therapeutic value in chronic liver disease.

Delayed liver regeneration with negative regulation of hepatocyte growth factor and positive regulation of transforming growth factor-beta1 mRNA after portal branch ligation in biliary obstructed rats

BACKGROUND

The influence of obstructive jaundice on liver regeneration is still controversial. The aim of this study was to investigate liver regeneration after portal branch ligation (PBL) in the jaundiced rat, focusing on hepatocyte growth factor (HGF) and transforming growth factor-beta1 (TGF-beta 1).

METHODS

Male Wistar rats underwent PBL or a sham operation 7 days after a common bile duct ligation. Liver wet weight, proliferating cell nuclear antigen labeling, HGF and TGF-beta 1 mRNA expression, and immunohistochemical staining with alpha-smooth muscle actin antibody were studied.

RESULTS

The rate of liver regeneration in jaundiced liver was decreased as compared to a non-jaundiced liver. DNA synthesis in the jaundiced non-ligated lobe was significantly lower than in the non-jaundiced liver as was the peak level of HGF mRNA expression after PBL. In contrast, the level of TGF-beta 1 mRNA expression was higher in the jaundiced liver, and alpha-smooth muscle actin staining showed that hepatic stellate cells were gradually activated into myofibroblast-like cells.

CONCLUSIONS

Obstructive jaundice decreased the expression of HGF mRNA and increased the expression of TGF-beta 1 mRNA, resulting in delayed liver regeneration after PBL. We suggest that hepatic stellate cells activated in obstructive jaundice may affect the expression of these growth factors.

Liver gene regulation in rats following both 70 or 90% hepatectomy and endotoxin treatment

BACKGROUND

The metabolic state effect of liver failure on liver gene regulation was evaluated in a rat model.

METHODS

Following 70 or 90% hepatectomy and lipopolysaccharide or vehicle treatment at intervals up to 24 h, the liver remnants were analyzed for mRNA levels for acute-phase, liver-specific and growth-related proteins.

RESULTS

After 70% hepatectomy mRNA for alpha 1-acid glycoprotein, alpha 2-macroglobulin, thiostatin and fibrinogen, haptoglobin increased three- to sevenfold (P < 0.05), and mRNA for cyclin D and histone 3 increased seven- and 15-fold (P < 0.05), respectively. After lipopolysaccharide injection and 70% hepatectomy were done, mRNA for acute-phase proteins raised significantly (P < 0.05), more to five to 20-fold, while mRNA for growth-related proteins raised significantly (P < 0.05) less to three- to fourfold. After 90% hepatectomy, acute-phase protein mRNA increased five- to ninefold (P < 0.05) more than after 70% hepatectomy, while mRNA for histone 3 and cyclin D did not increase within 24 h, which indicates a delayed growth after 90% hepatectomy. In 90% of hepatectomized rats treated with lipopolysaccharide, acute-phase protein mRNA raised three- to sixfold (P < 0.05) less than after vehicle treatment.

CONCLUSION

In endotoxemia from liver failure, the synthesis of acute-phase proteins is upregulated by gene regulation at the expense of that for regeneration, which may be an appropriate response for immediate survival. In severe liver failure, endotoxin may interfere with the appropriate gene regulation.

Delivery of a retroviral vector expressing human beta-glucuronidase to the liver and spleen decreases lysosomal storage in mucopolysaccharidosis VII mice

Mucopolysaccharidosis VII (MPS VII) is caused by beta-glucuronidase (beta-gluc) deficiency and results in lysosomal storage due to the inability to degrade glycosaminoglycans. Transfer of a beta-gluc gene into the liver reduces hepatic pathology as well as storage in other organs via uptake of secreted protein. A Moloney murine leukemia-based retroviral vector expressing the human beta-gluc cDNA was injected intravascularly into MPS VII mice during hepatocyte replication, which was induced with im injection of an adenoviral vector that transiently expressed hepatocyte growth factor (Ad.CMV. HGF). This procedure resulted in transduction of approximately 1% of hepatocytes, 1% of normal liver enzyme activity, and a reduction in lysosomal storage in the liver at 3.5 months. Surprisingly, controls that received retroviral vector without HGF had transduction of nonparenchymal cells in the liver, significant levels of enzyme and RNA in the liver at 2 but not 3.5 months, and reduced lysosomal storage at 3.5 months. Transduction was also achieved in the replicating cells of the spleen, where lysosomal storage was reduced. An approach using a retroviral vector without a growth factor might temporarily reduce lysosomal storage in the liver and spleen in humans. Addition of HGF might be used to augment and prolong gene transfer.

Hepatocyte growth factor in renal failure: promise and reality

Can science discover some secrets of Greek mythology? In the case of Prometheus, we can now suppose that his amazing hepatic regeneration was caused by a peptide growth factor called hepatocyte growth factor (HGF). Increasing evidence indicates that HGF acts as a multifunctional cytokine on different cell types. This review addresses the molecular mechanisms that are responsible for the pleiotropic effects of HGF. HGF binds with high affinity to its specific tyrosine kinase receptor c-met, thereby stimulating not only cell proliferation and differentiation, but also cell migration and tumorigenesis. The three fundamental principles of medicine-prevention, diagnosis, and therapy-may be benefited by the rational use of HGF. In renal tubular cells, HGF induces mitogenic and morphogenetic responses. In animal models of toxic or ischemic acute renal failure, HGF acts in a renotropic and nephroprotective manner. HGF expression is rapidly up-regulated in the remnant kidney of nephrectomized rats, inducing compensatory growth. In a mouse model of chronic renal disease, HGF inhibits the progression of tubulointerstitial fibrosis and kidney dysfunction. Increased HGF mRNA transcripts were detected in mesenchymal and tubular epithelial cells of rejecting kidney. In transplanted patients, elevated HGF levels may indicate renal rejection. When HGF is considered as a therapeutic agent in human medicine, for example, to stimulate kidney regeneration after acute injury, strategies need to be developed to stimulate cell regeneration and differentiation without an induction of tumorigenesis.

Experimental study of the effects of deletion variant of hepatocyte growth factor on hepatic ischaemia-reperfusion injury

BACKGROUND

Hepatic ischaemia-reperfusion (IR) injury is still a serious complication following liver surgery. The effect of the deletion variant of hepatocyte growth factor (dHGF) on hepatic IR injury was examined in rats.

METHODS

Male Wistar rats were divided into two groups after 90 min of partial liver ischaemia: the dHGF group which was given dHGF 0.5 mg/kg intravenously immediately after reperfusion, followed by 0.5 mg/kg every 12 h, and the control group, which received vehicle buffer only. Serum chemistry, histopathological findings and liver weights were compared between the groups.

RESULTS

In the dHGF group, the increase in serum alanine transaminase and hyaluronic acid levels was significantly reduced, and the serum albumin level increased after reperfusion. The extent of hepatic necrosis 24 h after reperfusion was decreased in the dHGF group. Moreover, the proportion of terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labelling-positive hepatocytes 6 h after reperfusion was reduced in the dHGF group. The non-ischaemic-, ischaemic- and whole-liver weight : body-weight ratio significantly increased in the dHGF group after reperfusion. The proportion of proliferating cell nuclear antigen-positive hepatocytes in the dHGF group markedly increased after 6 h after reperfusion in the non-ischaemic lobes, while in the ischaemic lobes it increased 24 h after reperfusion.

CONCLUSION

These data suggest that dHGF not only improves recovery from IR injury, but also accelerates recovery from these injuries. dHGF may be an effective pharmacological agent for prevention and treatment of hepatic IR injury.

Hepatoprotective action of adenovirus-transferred HNF-3gamma gene in acute liver injury caused by CCl(4)

Hepatocyte nuclear factor-3gamma (HNF-3gamma) is an important regulator of liver-specific genes and the expression of this factor is reduced in the liver injured by carbon tetrachloride (CCl(4)). Wistar rats were infected with a recombinant adenovirus carrying the cDNA for HNF-3gamma (AxCAHNF3gamma) via the tail vein and were treated with CCl(4) by intraperitoneal injection. Liver damage, such as swelling of the hepatocytes and increases in serum marker enzymes were markedly alleviated by AxCAHNF3gamma infection. Interestingly, hepatocyte growth factor (HGF) was strongly induced in the AxCAHNF3gamma-infected liver. Likewise, HNF-1alpha and HNF-1beta levels were increased, but HNF-3alpha and HNF-3beta levels were depressed in the liver. Our results suggest that the transduced HNF-3gamma gene leads to a hepatoprotective effect via the induction of HGF by the combined actions of liver-enriched transcription factors.

Hepatocyte growth factor supply accelerates compensatory hypertrophy caused by portal branch ligation in normal and jaundiced rats

BACKGROUND

Hepatocyte growth factor (HGF), first identified as the most potent mitogen for hepatocytes, significantly stimulates liver regeneration after hepatectomy. In this report, we examined whether HGF is also useful in accelerating compensatory hypertrophy caused by portal branch ligation in normal and jaundiced rats.

MATERIALS AND METHODS

Normal and reversible obstructive jaundiced rats underwent portal ligation of the left lateral and median branches, which supply approximately 70% of the total volume of the liver. Simultaneously, the animals were continuously treated with either recombinant human HGF (rhHGF) or vehicle alone via an intraperitoneally implanted osmotic pump. Two and four days after portal ligation, the degree of compensatory hypertrophy in unoccluded lobes was examined by measuring the wet weight ratios of the unoccluded lobes to the whole liver and the 5-bromo-2'-deoxyuridine labeling index of hepatocytes in each group.

RESULTS

The HGF treatment significantly increased the wet weight ratios and the DNA synthesis in nonoccluded lobes 2 and 4 days after portal ligation in both normal and jaundiced rats. Moreover, rhHGF supply promptly decreased serum total bilirubin level in jaundiced rats.

CONCLUSIONS

Continuous rhHGF administration not only accelerates compensatory hypertrophy in normal and jaundiced rats but also ameliorates hyperbilirubinemia in jaundiced rats.

Morphologic alteration of hepatocytes and sinusoidal endothelial cells in rat fatty liver during cold preservation and the protective effect of hepatocyte growth factor

BACKGROUND

Fatty liver grafts are considered to be one of the main factors of primary nonfunctioning graft in transplantation. We investigated here, the hepatic damage during cold preservation in a rat fatty liver model by ultrastructural observation, and examined the effect of human recombinant hepatocyte growth factor (hrHGF) on amelioration of the cold-preserved graft condition.

METHODS

Wistar rats were fed a choline-deficient diet (CDD) for 7 days. Livers were stored in cold University of Wisconsin (UW) solution for 0, 4, and 24 hr. We evaluated the ultrastructural alteration of the hepatocytes, sinusoidal architecture, and endothelial cells (SECs) by scanning and transmission electron microscopy. Ex vivo, we measured alanine aminotransferase (ALT) in first effluent as an index of hepatocyte injury and the hyaluronic uptake rate (HUR) as that of SEC damage. We injected hrHGF into rats fed CDD for 7 days through the portal vein and also added it to the UW solution to determine whether or not the agent ameliorated the hepatic damage in cold-preserved fatty livers.

RESULTS

In rats fed CDD for 7 days, the lesion occupied by fat deposits appeared to enlarge with the duration of cold preservation leading to the disarrangement of sinusoidal architecture. Furthermore, sinusoidal endothelial damage, in which gaps, blebs, microvilli, and sinusoid denudation were detected, appeared to be more severe in these livers than in the corresponding control livers. ALT significantly increased in the 4-hr cold-preserved livers of rats fed CDD for 7 days. HUR decreased with 4-hr cold preservation and/or with CDD feeding. Administration of hrHGF prevented the expansion of fatty droplets and reduced SEC injury as detected by morphological observations. Increase of ALT in first effluent was inhibited to about one fourth the level observed in the 4-hr cold-preserved livers of rats fed CDD. Moreover, HUR significantly increased with the pretreatment of hrHGF.

CONCLUSION

The hepatic injury in both hepatocytes and SECs in cold-preserved fatty liver graft developed more rapidly and severely than in the corresponding controls and demonstrated a protective effect of hrHGF.

Hepatocyte growth factor prevents lipopolysaccharide-induced hepatic sinusoidal endothelial cell injury and intrasinusoidal fibrin deposition in rats

BACKGROUND

Acute endotoxemia is known to cause activation of Kupffer cells as well as serious injury in parenchymal and nonparenchymal cells in the liver. We have recently shown that a continuous recombinant hepatocyte growth factor (rHGF) supply prevents lipopolysaccharide (LPS)-induced liver injury in rats. As an attempt to elucidate the mechanism, here we investigate the cytoprotective effect of rHGF on sinusoidal endothelial cells (SECs) in LPS-induced liver injury in rats.

MATERIALS AND METHODS

In order to supply rHGF continuously to the liver, syngenic rat fibroblasts genetically modified to secret rat rHGF were implanted in the spleen. Fourteen days after cell implantation, we injected LPS intravenously and evaluated SEC damage histologically and blood chemically.

RESULTS

Phosphotungstic acid-hematoxylin staining revealed that rHGF treatment greatly attenuated intrasinusoidal LPS-induced fibrin deposition. The ultrastructural changes in SECs caused by LPS administration in control rats were barely detectable in rHGF-treated rats. Blood chemical analyses showed that rHGF potently suppressed the LPS-induced increase in serum hyaluronic acid and transaminase levels.

CONCLUSIONS

Our results indicate an important role for HGF in SEC protection in vivo and would suggest a novel therapeutic strategy for liver diseases with SEC injury.

Portal branch ligation with a continuous hepatocyte growth factor supply makes extensive hepatectomy possible in cirrhotic rats

In a cirrhotic liver, the regenerative ability and specific functions are so impaired that excessive resection easily complicates postoperative liver dysfunction, which frequently leads to life-threatening multiple-organ failure. Hepatocyte growth factor (HGF), first identified as the most potent stimulator of DNA synthesis in primary hepatocytes, not only stimulates liver regeneration, but also accelerates hepatic function, improves fibrosis, and protects liver cells against injury. Therefore, we investigated the efficacy of preoperative portal branch ligation (PBL) (which can induce compensatory hypertrophy of the unaffected lobes) combined with a continuous HGF supply in the performance of extensive hepatectomy in cirrhotic rats. Cirrhosis was induced by intraperitoneal injections of dimethylnitrosamine (DMN) three times per week for 3 weeks. Five days after the last injection, when 70% hepatectomy is lethal, the rats underwent portal ligation of the left lateral and median branches (corresponding to approximately 70% of the total volume of the liver). Simultaneously, they were continuously treated with either recombinant human HGF (rhHGF) or vehicle from an intraperitoneally implanted osmotic pump. Four days after the portal ligation, the occluded lobes were resected. The HGF treatment rapidly increased both the wet weight of the unoccluded lobes and the hepatocellular DNA synthesis. The blood chemical analysis indicated that HGF significantly suppressed the posthepatectomy liver dysfunction. Most importantly, the HGF treatment markedly improved the survival rate of the rats at 48 hours after the major hepatectomy. In conclusion, PBL combined with a continuous HGF supply makes extensive hepatectomy possible in cirrhotic rats, mainly by promoting the hypertrophy of the unaffected lobes.

Hepatocyte growth factor induces hepatocyte proliferation in vivo and allows for efficient retroviral-mediated gene transfer in mice

Recombinant retroviral vectors are an attractive means of transferring genes into the liver because they integrate into the host cell genome and result in permanent gene expression. However, efficient in vivo gene transfer is limited by the requirement of active cell division for integration. Traditional approaches to induce liver proliferation have the disadvantage of inducing hepatocellular injury by delivery of toxins or by surgical partial hepatectomy. As a nontraumatic alternative, we show that exogenous hepatocyte growth factor (HGF) is a powerful and safe mitogen for the mature intact murine liver when delivered continuously into the portal vein. A 5-day infusion of human HGF (5 mg/kg/d) resulted in > 140% increase in relative liver mass, which returned to normal in 4 to 5 weeks. This clearly shows that an exogenous growth factor can induce robust liver proliferation in vivo. In addition, we show that the HGF-induced proliferation was independent of interleukin-6, an essential cytokine involved in liver regeneration after partial hepatectomy. When recombinant retroviral vectors were infused in combination with HGF, 30% of hepatocytes were stably transduced with no indication of hepatic injury or histopathology. These results show the ability to obtain a clinically relevant transduction efficiency with retroviral vectors in vivo without the prior induction of liver injury. The level of hepatic gene transfer achieved has the potential to be curative for a large number of genetic liver diseases.

Hepatocyte growth factor promotes liver regeneration with prompt improvement of hyperbilirubinemia in hepatectomized cholestatic rats

BACKGROUND

In hepatectomy for patients with liver cirrhosis or cholestasis, prolonged postoperative hyperbilirubinemia is a troublesome complication and, if uncontrolled, often leads to life-threatening hepatic failure. Hepatocyte growth factor (HGF), first identified as the most potent mitogen for primary hepatocytes, has been shown to have multiple biological properties on liver, including mitogenic, antifibrotic, and cytoprotective activities. This study investigated the beneficial effects of a perioperative HGF supply to jaundiced liver after hepatectomy in rats.

MATERIALS AND METHODS

As a model of jaundiced liver, we used an alpha-naphtylisocyocyanate (ANIT)-induced intrahepatic cholestasis model. Forty-eight hours after intraperitoneal injection of ANIT (75 mg/kg), when the total serum bilirubin level was moderately increased, a 70 % hepatectomy was performed. Human recombinant HGF (250 microgram/kg) (n = 15) or vehicle alone (n = 15) was intermittently administered to the rats 12 h before surgery and every 12 h after that until sacrifice.

RESULTS

Perioperative HGF treatment effectively accelerated hepatocellular DNA synthesis of cholestatic liver followed by increase in the regenerated liver weight. Moreover, HGF supply promptly improved hyperbilirubinemia within 24 h after surgery. Histological examination revealed that HGF administration attenuated periportal inflammation and formation of bile duct obstructions. Postoperative serum concentrations of tumor necrosis factor-alpha, a representative inflammatory cytokine, were not altered by HGF treatment.

CONCLUSIONS

Perioperative HGF supply not only promotes liver regeneration but also ameliorates hyperbilirubinemia in hepatectomized cholestatic rats. This mode of HGF treatment may be clinically useful for hepatectomy in patients with cholestasis.

Perioperative continuous hepatocyte growth factor supply prevents postoperative liver failure in rats with liver cirrhosis

Insufficient regeneration and dysfunction of cirrhotic liver following partial hepatectomy often make the resection extremely vulnerable to postoperative liver failure, which frequently leads to multiple organ failure. Hepatocyte growth factor (HGF), first identified as the most potent mitogen for primary hepatocytes, not only stimulates hepatic regeneration but also accelerates liver function, improves fibrosis, and protects liver cells against injury. Therefore, we investigated the ability of a continuous supply of HGF to cirrhotic livers to prevent postoperative liver failure in rats. After liver cirrhosis was induced in 40 rats by the intraperitoneal injection of dimethylnitrosamine (DMN) for 4 weeks, fibroblasts genetically modified to secret rat HGF or control fibroblasts were implanted in the spleens of 20 syngenic rats per group to supply HGF continuously and directly to the cirrhotic livers. Two weeks after the implantation, all rats underwent a 30% hepatectomy. The HGF administration significantly improved liver fibrosis at the time of operation, attenuated the postoperative hepatic damage on histological examination, markedly accelerated the liver regeneration at 24 h after the hepatectomy. The blood chemical analysis indicated that HGF significantly suppressed postoperative liver failure. Most importantly, the HGF treatment significantly improved the survival rate of the rats at 48 h after the hepatectomy. The perioperative continuous supply of HGF from the spleen effectively prevented liver failure following resection of cirrhotic livers in rats.