Hepatic fibrosis. Pathogenesis and principles of therapy

Effects of the tyrosine protein kinase inhibitor genistein on the proliferation, activation of cultured rat hepatic stellate cells

AIM: Hepatic stellate cell (HSC) plays a pivotal role in liver fibrosis and is considered as the therapeutic target for the treatment of hepatic fibrosis. Tyrosine protein kinase plays an important role in the proliferation, activation of HSC. The purpose of the study is to investigate the effects of the tyrosine protein kinase inhibitor genistein on the proliferation and activation of cultured rat HSC.

METHODS: Rat HSC were isolated from Wistar rats by in situ perfusion of collagenase and pronase and single-step density Nycodenz gradient. Culture-activated HSC were serum-starved and incubated with 10^-9 to 10^-5 mol/L concentration of genistein for 24, 48 or 72 h. In PDGF-induced HSC proliferation, HSC were stimulated with 10 μg·L^-1 PDGF-BB for 15 min, and then treated with genistein for the same time. Cell proliferation was measured by MTT assay and based on flow cytometric analysis of cell cycle. The α-smooth muscle actin (α-SMA) expression in HSC was studied with confocal laser microscopy and flow cytometry. c-fos, c-jun and cyclin D1 expression in HSC was also detected by flow cytometry.

RESULTS: Genistein inhibited basal and PDGF-induced proliferation of HSC at the concentration of 10^-8 to 10^-5 mol/L, and treatment with 10^-7 mol/L concentration of genistein for 48 h inhibited the HSC proliferation significantly (the inhibition rate was 70.3%, P < 0.05). Immunofluorescence detected by confocal laser microscopy and flow cytometry showed that treatment with 10^-7 mol/L genistein for 48 h suppressed the expression of α-SMA significantly in HSC (the specific fluorescence intensity were 60.2 ± 21.5 vs 35.3 ± 11.6 and 12.8 ± 10.4 vs 9.54 ± 6.39, respectively, both P < 0.05). The intensity of c-fos, c-jun and cyclin D1 expression of HSCs treated with 10^-7 mol/L genistein for 48 h was also significantly decreased compared with the controls.

CONCLUSION: Genistein influences proliferation of HSC, suppresses the expression of α-SMA in HSC and t inhibits the intensity of c-fos, c-jun and cyclin D1 expression of HSCs. Genistein has therapeutic potential against liver fibrosis.

Apoptosis of rat hepatic stellate cells induced by anti-focal adhesion kinase antibody

AIM: To explore the role of focal adhesion kinase (FAK) in the apoptosis in culture-activated rat hepatic stellate cells (HSCs) using a specific anti-FAK antibody.

METHODS: Rat HSCs were prepared from Wistar rats by in situ perfusion of collagenase and pronase and single-step density Nycodenze gradient. Culture-activated HSCs were serum-starved and treated with the anti-FAK antibodies for 24, 48 or 72 h. The apoptosis of HSC was detected by DNA-fragment assay, flow cytometry and caspase-3 activity determination. The expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA was assessed by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS: The experiment showed that anti-FAK antibodies induced apoptosis of culture-activated rat HSCs. This phenomenon displayed the classical features of apoptotic cell death (DNA fragmentation, cell cycle analysis) after treated with 30 mg·L^-1 FAK antibody for 72 h, and accompanied by a significant increase of caspase-3 activity (1208 ± 76) vs (309 ± 28) nmol·min^-1·g^-1, t = 208.5, P < 0.05. Meanwhile, treatment with the FAK antibody in HSCs could markedly decrease the TIMP-1 mRNA expression (0.07 ± 0.01 vs 0.38 ± 0.03, t = 2.72, P < 0.05).

CONCLUSION: FAK plays an important role in the survival of HSCs and the specific anti-FAK antibody could induce the apoptosis in rat HSCs.

Future research directions in idiopathic pulmonary fibrosis: summary of a National Heart, Lung, and Blood Institute working group

Idiopathic pulmonary fibrosis (IPF) is an insidious inflammatory fibroproliferative disease whose cause and course before diagnosis are unknown, and for which existing treatments are of limited benefit. The National Heart, Lung, and Blood Institute convened a working group to develop specific recommendations for future IPF research. Inflammatory and immune processes are involved in IPF pathogenesis, and current therapeutic strategies are aimed at suppressing the inflammation. Recent data suggest that the molecular processes underlying the fibrogenesis may provide new opportunities for therapeutic intervention. Specific areas of future research recommended by the working group include studies to elucidate the etiology of IPF, to develop novel diagnostic techniques and molecular diagnostics, to establish a program for identification of molecular targets for IPF treatment and identification and generation of agonists or antagonists that inhibit fibrogenesis, to foster investigations that couple the use of new technologies (e.g., laser capture microdissection, microarrays, and mass spectroscopic analysis of proteins) with data from the human genome project, to establish a national consortium of Clinical Centers of Excellence to conduct coordinated clinical and laboratory studies of well-characterized patients and patient-derived materials, and to stimulate research to develop animal models of persistent and progressive pulmonary fibrosis for evaluation of new intervention approaches.

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.