Hepatic Hepatocyte Growth Factor Levels Research Articles

Cylindromatosis gene CYLD regulates hepatocyte growth factor expression in hepatic stellate cells through interaction with histone deacetylase 7.

Hepatic fibrosis is considered as a physiological wound-healing response to liver injury. The process involves several factors, such as hepatocyte growth factor (HGF), which restrains hepatic injury and facilitates reversibility of fibrotic reaction in response to an acute insult. Chronic liver injury and sustained inflammation cause progressive fibrosis and, ultimately, organ dysfunction. The mechanisms tipping the balance from restoration to progressive liver tissue scarring are not well understood. In the present study, we identify a mechanism in which the tumor-suppressor gene, cylindromatosis (CYLD), confers protection from hepatocellular injury and fibrosis. Mice lacking CYLD (CYLD-/-) were highly susceptible to hepatocellular damage, inflammation, and fibrosis and revealed significantly lower hepatic HGF levels, compared to wild-type (WT) animals. Exogenous application of HGF rescued the liver injury phenotype of CYLD-/- mice. In the absence of CYLD, gene transcription of HGF in hepatic stellate cells was repressed through binding of histone deacetylase 7 (HDAC7) to the promoter of HGF. In WT cells, CYLD removed HDAC7 from the HGF promoter and induced HGF expression. Of note, this interaction occurred independently of the deubiquitinating activity of CYLD. Our findings highlight a novel link between CYLD and HDAC7, offering mechanistic insight into the contribution of these proteins to progression of liver disease. Thus, through regulation of HGF level, CYLD ameliorates hepatocellular damage and liver fibrogenesis.

Improvement of metabolic syndrome by irbesartan via the PPARγ/HGF pathway in apolipoprotein E knockout mice

Irbesartan, a partial agonist of peroxisome proliferators activated receptor-γ (PPARγ), has been reported to improve insulin resistance and lipid profile in patients with diabetes mellitus or metabolic syndrome (MS). However, the down effectors of PPARγ have yet to be elucidated. Thus, in this study, we focused on the role of the hepatocyte growth factor (HGF) in the anti-metabolic effects of irbesartan, using apolipoprotein E (ApoE) knockout (KO) mice. ApoE KO mice placed on a high-fat diet (HFD) for 12 weeks were divided into four groups: i) the control (HFD only), ii) the HFD + irbesartan (5 mg/kg/day), iii) the HFD + irbesartan + GW9662, a PPARγ antagonist (0.5 mg/kg/day) and iv) the HFD + irbesartan + anti-HGF neutralizing antibody (200 μg/week). The liver and epididymal adipose tissues were evaluated histologically. Serum adiponectin and HGF levels were also measured by ELISA. Fatty liver (as detected by oil-red O staining) and macrophage infiltration were markedly reduced by irbesartan. Irbesartan treatment also reduced macrophage infiltration into epididymal adipose tissue and hypertrophy of adipocytes. However, these effects of irbesartan were attenuated by GW9662 as well as by anti-HGF neutralizing antibody. Serum and hepatic HGF levels were also markedly increased by irbesartan, whereas GW9662 decreased the HGF level. In conclusion, irbesartan, an angiotensin (Ang) receptor blocker (ARB) and partial agonist of PPARγ (metabosartan), demonstrated a reduction in fatty liver and chronic inflammation, such as macrophage infiltration, beyond its blood pressure-lowering effect. These favorable characteristics of irbesartan might be due to local HGF activation through its partial PPARγ agonistic action, in addition to Ang II blockade. Upregulation of local HGF by irbesartan might provide a novel advantage in a strategy for the prevention and treatment of cardiovascular diseases (CVDs).

Evaluation of hepatocyte growth factor in patients with biliary atresia

Background Hepatocyte growth factor (HGF) is a potent mitogen for mature hepatocytes in primary culture and seems to be a trigger factor for liver regeneration and proliferation after liver injury. The aim of this study was to evaluate the expression of HGF in patients with biliary atresia (BA). Methods Plasma levels of HGF were determined using an enzyme-linked immunosorbent assay from 19 patients with BA, 10 at the time of Kasai procedure (KP) and 9 at liver transplantation (LT), and 10 patients with nonicteric choledochal cyst served as control. Hepatic HGF level was quantitatively estimated using enzyme-linked immunosorbent assay and Western blotting. Hepatocyte growth factor messenger RNA (mRNA) expression of liver was measured with quantitative reverse transcriptase polymerase chain reaction. Immunohistochemical study of liver sections was evaluated by HGF staining. Results Plasma HGF levels in LT patients were significantly higher than in KP patients (2977.30 ± 1251.42 vs 960.17 ± 559.82 pg/mL, P < .01). Western blots showed increased hepatic HGF levels in LT group than in KP group (2.02 ± 0.86 vs 1.44 ± 0.72 pg/ μg total protein, P < .05). However, there were no differences in HGF mRNA expression. Immunohistochemical study showed significantly increased HGF staining in hepatocytes of LT livers than of KP livers. Conclusions Elevation of plasma and liver HGF levels could be related to the progression of liver cirrhosis in patients with BA. Hepatocyte growth factor might have a protective role, probably through the induction of hepatocyte proliferation, during the development of BA-associated liver cirrhosis.

P53 may positively regulate hepatocyte proliferation in rats

p53, known as a tumor suppressor gene, is a transcription factor that regulates various cellular functions. Recently, several growth factor gene promoters, including that of transforming growth factor α (TGF-α), were shown to be direct targets of p53-mediated transcription. Hepatic p53 mRNA is up-regulated during liver regeneration in rats. The aim of this study is to examine the role of p53 in hepatocyte proliferation. p53 protein levels were examined in rat hepatocytes cultured in the medium containing hepatocyte growth factor (HGF). p53 levels began to increase after 6 hours of incubation, reached a maximum at 18 hours, and decreased thereafter. DNA synthesis increased at 12 hours and peaked at 30 hours. When hepatocytes were incubated with p53 antisense oligonucleotide in addition to HGF, increases of p53 and TGF-α levels were suppressed, and DNA synthesis was reduced. The increases of TGF-α levels and DNA synthesis were also suppressed by a chemical inhibitor of p53, pifithrin-α. In rats after two-thirds partial hepatectomy, hepatic p53 increased and reached maximal levels around 16 hours when hepatic HGF levels have been shown to reach a maximum followed by an increase in hepatic TGF-α levels or hepatocyte proliferation. In contrast, sham-operated rats showed minor elevations of hepatic p53 levels. In conclusion, p53 production is stimulated by HGF and may contribute to the proliferation of rat hepatocytes. Considering previous findings indicating the importance of endogenous TGF-α for the proliferation of hepatocytes stimulated by HGF, TGF-α might play a role in HGF-p53 mediated hepatocyte proliferation. (H EPATOLOGY 2002;36:336-344.)

Polymorphonuclear neutrophils are a source of hepatocyte growth factor in patients with severe alcoholic hepatitis

Background/Aims: Hepatocyte growth factor (HGF) is a pleiotropic cytokine involved in liver regeneration. Plasma HGF levels correlate with survival and hepatocyte proliferation in alcoholic hepatitis (AH). As AH is accompanied by inflammation, neutrophilia and polymorphonuclear neutrophil (PMN) infiltration of the liver, we postulated that PMN could be a source of HGF in such patients. Methods: We studied 25 patients with severe AH in comparison with 20 alcoholic cirrhotic patients without AH and 20 healthy controls; the impact of a 28-day course of corticosteroids was evaluated in patients with AH. Results: On day 0, HGF plasma and homogenized liver tissue levels were markedly increased in AH patients as compared to controls. The role of PMN in HGF production during AH was confirmed by a significantly higher ex-vivo HGF production capacity of lipopolysaccharide-stimulated blood PMN from AH patients relative to both control groups. Formyl-Methionyl-Leucyl-Phenylalanine-induced PMN release of HGF (degranulation conditions) was also higher in AH patients. In this setting, we found that HGF release by PMN ex vivo correlated strongly with HGF plasma levels, and that the degree of hepatic PMN correlated strongly with hepatic HGF levels. HGF plasma levels and ex-vivo HGF release by PMN were unaffected by steroid therapy. Conclusions: These findings suggest that, by releasing HGF, PMN could participate in liver regeneration during severe alcoholic hepatitis.

The Mitogenic Activity of Hepatocyte Growth Factor on Rat Hepatocytes Is Dependent upon Endogenous Transforming Growth Factor-α

Both transforming growth factor-alpha (TGF-alpha) and hepatocyte growth factor (HGF) induce DNA synthesis in hepatocytes in vitro and in vivo. Hepatic and circulating levels of HGF have been reported to increase before an increase in TGF-alpha levels in several rat models of liver regeneration. In addition, serum TGF-alpha levels increase after an increase in serum HGF levels in patients with either partial hepatectomy or acute hepatitis. In this study, we investigate the significance of TGF-alpha in hepatocyte proliferation. TGF-alpha contents and DNA synthesis in cultured rat hepatocytes increased in response to HGF addition to the culture medium in a dose-related manner. These increases were suppressed by the addition of anti-sense TGF-alpha mRNA oligonucleotide. Furthermore, the addition of anti-TGF-alpha rabbit IgG suppressed the increase in DNA synthesis. When the anti-TGF-alpha antibody was administered to rats after partial hepatectomy, the number of mitotic hepatocytes was reduced in comparison to rats treated with normal rabbit IgG. These results were observed even though hepatic HGF levels were increased equally in rats given either anti-TGF-alpha antibody or normal rabbit IgG. Our results suggest that HGF stimulates TGF-alpha production in rat hepatocytes, and that the mitogenic activity of HGF depends on endogenous TGF-alpha activity.

Involvement of Hepatocyte Growth Factor on Hepatocarcinogenesis Induced by Peroxisome Proliferators

Hepatocyte growth factor (HGF) has been known to enhance the growth of normal hepatocytes, but also to inhibit the growth of neoplastic cells. This article examines the involvement of HGF in the hepatocarcinogenesis caused by peroxisome proliferators (PPs). Up to 78 wk after male F-344 rats were orally given (4-chloro-6-[2,3-xylidino]-2-pyrimidinylthio) acetic acid (Wy-14,643), the hepatocarcinomas and (pre)neoplastic nodules in the livers were observed. At that time, the content of HGF and the expression of HGF mRNA in the liver tumors were significantly decreased. These changes were observed also in the liver of rats treated with other PPs, such as dehydroepiandrosterone and di(2-ethylhexyl)phthalate, but were not observed in tumors induced by genotoxic carcinogens (diethylnitrosamine-phenobarbital). In in vivo experiments, the formation of preneoplastic lesions and the tumors caused by Wy-14,643 administration were markedly suppressed by i.v.-injection of HGF in a dose-dependent manner. In the colony assay using (pre)neoplastic cells from livers of Wy-14,643-treated rats, HGF inhibited the colony formation of (pre)neoplastic cells in a dose-dependent manner. These findings may indicate that decreases in hepatic HGF levels are common and specific events induced by PPs, but not by genotoxic carcinogens, and that those changes play an important role in the promotion of neoplastic or preneoplastic cell growth induced by PPs.

Transforming Growth Factor α Levels in Liver and Blood Correlate Better than Hepatocyte Growth Factor with Hepatocyte Proliferation during Liver Regeneration

Transforming growth factor alpha (TGFalpha) and hepatocyte growth factor (HGF) are mitogens for hepatocytes in vitro and in vivo, produced by hepatocytes or nonparenchymal cells such as stellate cells in the liver. It is still uncertain whether TGFalpha and HGF are essential for liver regeneration. To assess the role of these growth factors in liver regeneration, their circulating and hepatic levels were studied in various rat models of liver regeneration. Hepatic and plasma HGF levels were increased with increased number of mitotic hepatocytes in rats after partial hepatectomy or carbon tetrachloride intoxication. However, hepatic HGF levels were decreased despite an increased number of mitotic hepatocytes and increased or unchanged plasma HGF levels in rats given phenobarbital and in rats after dimethylnitrosamine intoxication, which can induce hepatic necrosis after apoptosis of hepatic stellate cells. In contrast, hepatic and serum TGFalpha levels were increased in all of the models. In sham-operated rats with no increased number of mitotic hepatocytes, hepatic and circulating levels of HGF were increased, whereas those levels of TGFalpha were unchanged. The results indicate that TGFalpha levels in liver and blood more closely correlate with hepatocyte mitogenesis than HGF levels.

Decreased hepatocyte growth factor level by Wy-14,643, non-genotoxic hepatocarcinogen in F-344 rats.

We examined the role of hepatocyte growth factor (HGF) in the hepatocarcinogenesis caused by [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (Wy-14,643), a peroxisome proliferator. Wy-14,643 (100 mg/kg body wt or 0.1% (w/w) in diet) was given orally to male F-344 rats for up to 78 weeks. At 78 weeks the hepatocarcinomas or adenomas in the livers of Wy-14,643-treated rats were observed. Markedly decreased amounts of hepatic HGF mRNA were observed in rats fed Wy-14,643 for 78 weeks. The degree of reduction was higher in the tumour portions of the liver than in the normal portions. After 7 days of treatment with Wy-14,643 (100 mg/kg body wt), the expression of hepatic HGF mRNA was slightly decreased. Wy-14,643 treatment resulted in a time-dependent decrease in hepatic HGF mRNA levels to 63% of the control level after 14 days of treatment. In long-term treatment (18-40 weeks), hepatic HGF mRNA levels were reduced further, reaching 44% of the control level at the 40-week stage. As shown by ELISA, the amounts of hepatic and plasma HGF were significantly decreased by 60 and 50%, respectively, compared with controls. The degree of the reduction correlated with the level of hepatic HGF mRNA. In the lung and kidney, also HGF secretory organs, Wy-14,643 slightly reduced the amount of HGF mRNA. In the colony assay using preneoplastic or neoplastic cells from Wy-14,643-treated livers, 5-15 ng/ml of HGF, which induces proliferation in normal hepatocytes, inhibited the colony formation of neoplastic or preneoplastic cells. The inhibitory effect was dependent on HGF concentration. In the presence of 300 ng/ml HGF, the growth of colonies was suppressed to 36% of the control level. These findings indicate that reductions in hepatic HGF levels, induced by Wy-14,643, may play an important role in the promotion of neoplastic or preneoplastic cell growth.