Fibrodynamics-elucidation of the mechanisms and sites of liver fibrogenesis

Angiotensin-converting enzyme inhibitor prevents oxidative stress, inflammation, and fibrosis in carbon tetrachloride-treated rat liver

Hepatic fibrosis is a common feature of chronic liver injury, and the involvement of angiotensin II in such process has been studied earlier. We hypothesized that anti-angiotensin II agents may be effective in preventing hepatic fibrosis. In this study, Long Evans female rats were used and divided into four groups such as Group-I, Control; Group-II, Control + ramipril; Group-III, CCl4; and Group-IV, CCl4 + ramipril. Group II and IV are treated with ramipril for 14 d. At the end of treatment, the livers were removed, and the level of hepatic marker enzymes (aspartate aminotransferase, Alanine aminotransferase, and alkaline phosphatase), nitric oxide, advanced protein oxidation product , catalase activity, and lipid peroxidation were determined. The degree of fibrosis was evaluated through histopathological staining with Sirius red and trichrome milligan staining. Carbon-tetrachloride (CCl4) administration in rats developed hepatic dysfunction and raised the hepatic marker enzymes activities significantly. CCl4 administration in rats also produced oxidative stress, inflammation, and fibrosis in liver. Furthermore, angiotensinogen-inhibitor ramipril normalized the hepatic enzymes activities and improved the antioxidant enzyme catalase activity. Moreover, ramipril treatment ameliorated lipid peroxidation and hepatic inflammation in CCl4-treated rats. Ramipril treatment also significantly reduced hepatic fibrosis in CCl4-administered rats. In conclusion, our investigation suggests that the antifibrotic effect of ramipril may be attributed to inhibition of angiotensin-II mediated oxidative stress and inflammation in liver CCl4-administered rats.

Effects of estradiol on type I, III collagens and TGF β1 in hepatic fibrosis in rats

AIM

To study the effects of estradiol on the production of collagen I, III and transforming growth factor β₁ (TGF β₁) in experimental fibrosis in rats induced by carbon tetrachloride (CCL4), and to investigate the suppressive effects of estrogen on liver fibrosis.

METHODS

Rats were randomly allocated into a normal control group, a model control group, a therapy control group and an estradiol group. Liver fibrosis was induced by CCL₄ administration. The estradiol group, apart from the administration of CCL₄, was treated subcutaneously with estradiol (benzoic estradiol) 1 mg/kg twice weekly. At the end of week 8, all the rats were sacrificed. Liver inflammation and collagen deposition were observed with HE and Masson's collagen stains, analyzed with scoring and staging systems. Type I, III collagens and TGF β₁ were observed with immunohistochemical method.

RESULTS

CCL₄ group had the typical liver fibrosis compared with normal control group. The fibrous septa were formed in CCL₄ group rats, and collagens were accumulated and deposited in the sinusoids and liver lobules. The expression of type I , III collagens (0.58±0.26 vs 6.34±2.24, 1.07±0.49 vs 5.28±1.28, P<0.001) and TGF β₁ was significantly increased. Estradiol significantly attenuated collagen accumulation (P<0.05) in the fibrotic livers, and decreased type I , III collagens (2.47±0.76 vs 6.34±2.24, 3.02±1.20 vs 5.28±1.28, P<0.05) and TGF β₁ expression in the liver.

CONCLUSION

Estradiol treatment reduces the synthesis of hepatic type I , III collagens and TGF β₁ in the fibrotic liver induced by CCL₄ administration, and attenuates hepatic fibrosis.

Effects of ET-1 and NO on hepatic hemodynamics at various stages of isolated perfused cirrhotic liver in rats

AIM

To investigate the effects of ET-1, NO on hepatic hemodynamics in isolated perfused rat liver at various stages of liver cirrhosis (LC).

METHODS

LC was induced by an intraperitoneal injection of CCL₄ combined with ethanol as drinking water. According to time points of CCL₄ injection, and combined with histopathological changes of liver and ascites, the isolated perfusion of liver was performed at a constant flow rate to determine the modulating effects of ET-1 and NO in the ends of 9th week (E-LC) and 14^th week (L-LC) after injected CCL₄.

RESULTS

After perfusion of L-NAME into the portal vein, there were no significant changes in the perfused pressure of portal vein (PP) and the hepatic venous pressure (Phv) of the L-LC group, the E-LC group and control group (P>0.05). After perfusion of ET-1, the PP of each group increased significantly (P<0.01). The elevated ranges of PP of the L-LC group was more than that of the E-LC group (P<0.01), both of which were higher than that of the control group (P<0.01). Compared with the ET-1 groups, the PP of the control group, the E-LC group and the L-LC group increased significantly (P<0.05) after perfusion of ET-1+L-NAME. There were no significant differences between the elevated ranges of PP of the L-LC and that of the E-LC group (P>0.05), both of which were more than that of the control group (P<0.01).

CONCLUSION

ET-1 plays a key role in elevating intra-hepatic resistance, facilitating synthesis of NO, which grow stronger in LC. With the development of LC, the compensation of NO decreases further. It is considered that antagonist of ET receptor and NO provider can increase synthesis of NO and be thus used in treatment of the high pressure of portal vein.

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Changes in serum and histology of patients with chronic hepatitis B after interferon alpha-2b treatment

AIM: Chronic hepatitis B is a serious health problem. Interferon has long been used to treat Chronic hepatitis B. To evaluate the effects of interferon on chronic hepatitis B better, we designed the study to investigate the changes in sera and liver histology of patients with chronic hepatitis B after interferon alpha-2b treatment.

METHODS: Twenty-four patients with chronic hepatitis B were enrolled in this study. They all received interferon alpha-2b treatment as following: 3 million units, i.m. t.i.w., for 18 weeks. Sera of all patients were obtained respectively for evaluation of ALT, HBsAg, HBcAg, HBeAg, HBV DNA and TIMP-1 before and after interferon treatment, also a liver biopsy pre- and post-treatment was performed for comparison of HAI, HBsAg, HBcAg, HBeAg, TIMP-1 and activated HSC in the liver tissue.

RESULTS: Patients who had normalization of serum ALT and seroconversion of HBeAg and/or HBV DNA (blot hybridization) after treatment were defined as responders. The response rate in this study group was 37.5% (7/24). Compared to pretreatment, the serum HBV DNA and TIMP-1 decreased significantly (P < 0.05), so did the HAI, HBcAg, HBeAg, TIMP-1 and activated HSC (P < 0.05).

CONCLUSION: The significant decrease in HBV DNA in sera, the seroconversion of HBeAg, and the decrease of viral expression in liver indicated that interferon alpha-2b treatment can inhibit viral replication. The normalization of ALT in sera and the improvement of HAI in liver showed that interferon alpha-2b can improve the liver histology of patients with chronic hepatitis B. At the same time, interferon alpha-2b treatment can reduce the TIMP-1 in serum and liver and decrease the number of activated HSC, which may allievate or inhibit hepatic fibrosis. Although the response rate was unsatisfactory, interferon play a benefical role on patients with chronic hepatitis B in other respects. We still need further studies to improve the therapy effects.

Effects of tetrandrine on calcium and potassium currents in isolated rat hepatocytes

AIM: To study the effects of tetrandrine (Tet) on calcium release-activated calcium current (I_CRAC), delayed rectifier potassium current (I_K), and inward rectifier potassium currents (I_K1) in isolated rat hepatocytes.

METHODS: Hepatocytes of rat were isolated by using perfusion method. Whole cell patch-clamp techniques were used in our experiment.

RESULTS: The peak amplitude of I_CRAC was -508 ± 115 pA (n = 15), its reversal potential of I_CRAC was about 0 mV. At the potential of -100 mV, Tet inhibited the peak amplitude of I_CRAC from -521 ± 95 pA to -338 ± 85 pA (P < 0.01 vs control, n = 5), with the inhibitory rate of 35% at 10 µmol/L and from -504 ± 87 pA to -247 ± 82 pA (P < 0.01 vs control, n = 5), with the inhibitory rate of 49% at 100 µmol/L, without affecting its reversal potential. The amplitude of I_CRAC was dependent on extracellular Ca²⁺ concentration. The peak amplitude of I_CRAC was -205 ± 105 pA (n = 3) in tyrode’s solution with Ca²⁺ 1.8 mmol/L (P < 0.01 vs the peak amplitude of I_CRAC in external solution with Ca²⁺ 10 mmol/L). Tet at the concentration of 10 and 100 µmol/L did not markedly change the peak amplitude of delayed rectifier potassium current and inward rectifier potassium current (P > 0.05 vs control).

CONCLUSION: Tet protects hepatocytes by inhibiting I_CRAC, which is not related to I_K and I_K1.

Estrogen reduces CCL4- induced liver fibrosis in rats

AIM: Chronic liver diseases, such as fibrosis or cirrhosis, are more common in men than in women. This gender difference may be related to the effects of sex hormones on the liver. The aim of the present work was to investigate the effects of estrogen on CCL₄-induced fibrosis of the liver in rats.

METHODS: Liver fibrosis was induced in male, female and ovariectomized rats by CCL₄ administration. All the groups were treated with estradiol (1 mg/kg) twice weekly. And tamoxifen was given to male fibrosis model. At the end of 8 wk, all the rats were killed to study serum indicators and the livers.

RESULTS: Estradiol treatment reduced aspartate aminotransferase (AST), alanine aminotransferase (ALT), hyaluronic acid (HA) and type IV collagen (CIV) in sera, suppressed hepatic collagen content, decreased the areas of hepatic stellate cells (HSC) positive for α-smooth muscle actin (α-SMA), and lowered the synthesis of hepatic type I collagen significantly in both sexes and ovariectomy fibrotic rats induced by CCL₄ administration. Whereas, tamoxifen had the opposite effect. The fibrotic response of the female liver to CCL₄ treatment was significantly weaker than that of male liver.

CONCLUSION: Estradiol reduces CCL₄-induced hepatic fibrosis in rats. The antifibrogenic role of estrogen in the liver may be one reason for the sex associated differences in the progression from hepatic fibrosis to cirrhosis.

Salvia miltiorrhiza monomer IH764-3 induces hepatic stellate cell apoptosis via caspase-3 activation

AIM: To investigate the effects of IH764-3 on HSC apoptosis, and the expression of caspase-3 protein in HSC apoptotic process.

METHODS: HSCs were cultured in medium with different IH764-3 doses (10 μg·mL^-1, 20 μg·mL^-1, 30 μg·mL^-1, 40 μg·mL^-1) and without IH764-3, and HSC proliferation was quantitatively measured by ³H-thymidine incorporation. The morphological changes of HSCs were observed with transmission electron microscope after exposure to the dose of 40 μg·mL^-1 of IH764-3 for 48 hr. The apoptosis rates were detected by annexin V/PI and TdT-mediated dUTP nick end labeling (TUNEL). The expression of caspase-3 protein was determined by flow cytometry.

RESULTS: (1) HSC proliferation rates induced with different IH764-3 doses (10 μg·mL^-1, 20 μg·mL^-1, 30 μg·mL^-1, 40 μg·mL^-1) were significantly reduced compared with that of the control group (P < 0.01). (2) With the doses above, IH764-3 dose-dependently produced HSC apoptosis rates of 6.7% (9.4%), 9.3% (21.6%), 15.1% (27.2%) and 19.0% (28.4%) respectively, by annexin V and PI-labeled flow cytometry assay (or TUNEL), while it was only 2.3% (6.7%) in the control. (3) The expression of caspase-3 protein in IH764-3 groups was significantly higher than that of the control (P < 0.05).

CONCLUSION: Within the dose range used in present study, IH764-3 can inhibit HSC proliferation, as well as enhance HSC apoptosis. Furthermore, IH764-3 can significantly increase the caspase-3 protein expression.

Effects of Yigan Decoction on proliferation and apoptosis of hepatic stellate cells

AIM: To investigate the effects of Chinese herb Yigan Decoction on proliferation and apoptosis of the hepatic stellate cells (HSC) in vitro.

METHODS: The study in vitro was carried out in the culture of HSC lines. Various concentrations of Yigan Decoction were added and incubated. Cell proliferation was detected with MTT colorimetric assay. Cell apoptosis was detected by electron microscopy, flow cytometry and TUNEL.

RESULTS: The proliferation of HSC was inhibited by Yigan Decoction, which depending on dose and time significantly. The HSC proliferation rates of groups at the end concentrations 144 and 72 (g·L^-1) were 21.62% and 40.54% respectively, significantly lower than that of normal control group (P < 0.01). The HSC proliferation rates of groups at the end concentrations 36, 18 and 9 (g·L^-1) were 54.05%, 45.95% and 51.35% respectively, lower than that of control group (P < 0.05). When the end concentration was 4.5 g·L^-1, the proliferation rate was 83.78%, which appeared no significant differences compared with control group. At the same concentrations of 18 g·L^-1, the inhibitory effects of Yigan Decoction at 24 h, 48 h and 72 h time point were observed, the effects were time-dependent, and reached a peak at 72 h. Meanwhile, it was showed that the inducing effects of Yigan Decoction on HSC apoptosis were dose-dependent and time-dependent. The apoptosis index (AI) was detected by TUNEL. After Yigan Decoction had been incubated for 48 h at the end concentration of 18 g·L^-1, the AI (14.5 ± 3.1)% was significantly higher than that of control group (4.3 ± 1.3)% (P < 0.01). When visualized under transmission electron microscopy, some apoptotic stellate cells were found, i.e. dilated endoplasmic reticulum, irregular nuclei, chromatin condensation and heterochromatin ranked along inside of nuclear membrane. By flow cytometry detection, after HSC was treated with Yigan Decoction at different concentrations of 36, 18 and 9 (g·L^-1) for 48 h, AI (%) were 13.3 ± 3.2, 10.7 ± 2.7 and 10.1 ± 2.5 respectively, which were significantly higher than that of control group (4.1 ± 1.9) (P < 0.01). At the same concentration of 18 g· L^-1 for 24 h, 48 h and 72 h, AI (%) were 9.3 ± 1.8, 10.7 ± 2.7 and 14.6 ± 4.3 respectively, which were significantly higher than that of control group (P < 0.01).

CONCLUSION: Yigan Decoction could significantly inhibit HSC proliferation and increase the apoptosis index of HSC dose-dependently and time-dependently, which may be related to its mechanism of antifibrosis.

Protective effect of estradiol on hepatocytic oxidative damage

AIM: To examine the protective effect of estradiol on the cultured hepatocytes under oxidative stress.

METHODS: Hepatocytes of rat were isolated by using perfusion method, and oxidative stress was induced by a serum-free medium and FeNTA. MDA level was determined with TBA method. Cell damage was assessed by LDH assay. Apoptosis of hepatocytes was assessed with cytoflowmetric analysis. Expression of Bcl-xl in cultured hepatocytes was detected by Western blot. The radical-scavenging activity of estradiol was valued by its ability to scavenge the stable free radical of DDPH.

RESULTS: Oxidative stress increased LDH (from 168 ± 25 × 10^-6 IU•cell^-1 to 780 ± 62 × 10^-6 IU•cell^-1) and MDA (from 0.28 ± 0.07 × 10^-6 nmol·cell^-1 to 1.35 ± 0.12 × 10^-6 nmol•cell^-1) levels in cultured hepatocyte, and estradiol inhibited both LDH and MDA production in a dose dependent manner. In the presence of estradiol 10^-6 mol•L^-1, 10^-7 mol•L^-1 and 10^-8 mol•L^-1, the LDH levels are 410 ± 53 × 10^-6 IU•cell^-1 (P < 0.01 vs oxidative group), 530 ± 37 × 10^-6 IU•cell^-1 (P < 0.01 vs oxidative group), 687 ± 42 × 10^-6 IU•cell^-1 (P < 0.05 vs oxidative group) respectively, and the MDA level are 0.71 ± 0.12 × 10^-6 nmol•cell^-1 (P < 0.01vs oxidative group), 0.97 ± 0.11 × 10^-6 nmol•cell^-1 (P < 0.01 vs oxidative group) and 1.27 ± 0.19 × 10^-6 nmol•cell^-1 respectively. Estradiol suppressed apoptosis of hepatocytes induced by oxidative stress, administration of estradiol (10^-6 mol/L)decreased the apoptotic rate of hepatocytes under oxidative stress from 18.6% ± 1.2% to 6.5% ± 2.5%, P < 0.01. Bcl-xl expression was related to the degree of liver cell damage due to oxidative stress, and estradiol showed a protective action.

CONCLUSION: Estradiol protects hepatocytes from oxidative damage by means of its antioxidant activity.

Effects of AT1 receptor antagonist, losartan, on rat hepatic fibrosis induced by CCl4

AIM: To investigate effect o f losartan, an AT1 receptor antagonist, on hepatic fibrosis induced by CCl₄; and to determine whether or not AT1 receptors are expressed on hepatic stellate cells.

METHODS AND RESULTS: Fifty male Sprague-Dawley rats, weighing (180 ± 20) g, were randomized into five groups (control group, model group, and three los artan treated groups), in which all rats were given the subcutaneous injection o f 40% CCl₄ (every 3 days for 6 weeks) except for rats of control group. Rats of losartan-treated groups were treated with losartan (20 mg/kg, 10 mg/kg, 5 mg/kg, daily gavage). After 6 weeks liver tissue and serum samples of all rats were examined. Serum hyaluronic acid (HA), procollagen type III (PC III) were detected by radioimmunoassays. van Giesion collagen staining was used to evaluate the extracellular matrix of rats with liver fibrosis. The expression of AT1 receptors, transforming growth factor-beta (TGF-β), and alpha-smooth muscle actin (α-SMA) in liver tissue were determined by immunohistochemical techniques. Compared with model group, serum ALT and AST of losartan-treated groups were significantly reduced (t = 4. 20, P < 0.01 and t = 4.57, P < 0.01). Serum HA and PC III also had significant differences (t = 3.53, P < 0.01 and t = 2.20, P < 0.05). The degree of fibrosis was improved by losartan and correlated with the expressions of AT1 receptors, TGF-β, and α-SMA in liver tissue.

CONCLUSION: AT1 receptor antagonist, losartan, could limit the progression of the hepatic fibrosis induced by CCl₄. The mechanism may be relat ed to the decrease in the expression of AT1 receptors and TGF-β, a meliorating the injury of hepatocytes; activation of local renin-angiotensin system might relate to hepatic fibrosis; and during progression of fibrosis, activated hepatic stellate cells might express AT1 receptors.