| Hepatic fibrosis, of which cirrhosis is the most advanced stage, can result from chronic liver disease due to any cause. The current view envisions fibrosis as a programmed response to injury, which is dynamic and reversible. The main pathological characteristic of hepatic fibrosis is the increased and irregular deposition of extracellular matrix (ECM) components. Hepatic stellate cells (HSCs) play a pivotal role in this process. The activation of HSCs may result in their spontaneous proliferation with a strong fibrogenic activity. In recovery period, the apoptosis of HSCs increases significantly. So the proliferation and apoptosis of HSCs play a key role in the process of formation and resolution of hepatic fibrosis.Integrins are the main mediators of the complicated interaction between HSCs and ECM components. A number of observations strongly suggest that ligand occupancy, integrin receptor clustering and their combination trigger the aggregation of focal adhesion kinase(FAK) in focal adhesion plaque(FAP) and autophosphorylation of FAK at Tyr397 in the N-terminal domain. The activation of FAK may initiate many of the signaling pathways. Among them, RAS-dependent mitogen-activated protein kinase (MAPK) pathway is the clearest. Extracellular signal-regulated kinase1/2(ERK1/2) is a member of MAPK family. The RAS-RAF-MEK-ERK pathway is involved in many cellular behaviors, such as proliferation, migration, adhesion and apoptosis.Up to now, the expression and function of integrins and ECM components such as fibronectin(FN)have been reported in liver, but few studies have addressed the intercellular signal transduction pathways. Hence, we set about our research from the interaction of HSCs and ECM.Through experiments in vivo and in vitro, the roles of integrin signal pathways in hepatic fibrosis and HSC proliferation and apoptosis were studied. The experiments contained four parts as below: Part One: Increased Expression of FAK, ERK, during Hepatic Fibrogenesis and Proliferation, Apoptosis of HSCs Objective: To explore the dynamic expression of FAK, ERK1 and their mRNA in the hepatic flbrogenesis and the relation with HSC proliferation and apoptosis in ratsMethods: The Sprague Dawley rats were randomly divided into two groups, i.e., sham operation group and model group(bile duct ligation, BDL). Livers in model group were harvested at fixed time points: 2hr, 6hr, 2d, Iwk, 2wk, 3wk and 4wk after operation. Livers in sham operation group were harvested at 4wk after operation. Histopathological changes were evaluated by hematoxylin and eosin staining, and by Masson's trichrome method. FAK, ERKi mRNA in the livers were determined by reverse transcription-polymerase chain reaction (RT-PCR), while the distributions of FAK >. ERKi in the livers were assessed immunohistochemistrically. Numbers of activated HSCs were quantified after alpha smooth muscle actin( a -SMA) staining. HSC apoptosis was detected by terminal UDP-nick end labelling (TUNEL) staining together with a -SMA staining, and quantified at each time point. Results: With the development of hepatic fibrosis, the positive cells of a -SMA increased obviously. They mainly resided in the cells of portal ducts, fiber septa, perisinuses and around the proliferated bile ducts. The positive areas of the rat livers in model groups at week 1 to 4(12.88%+ 2.63%, 22.65%+2.16%, 27.45%+1.86%, 35.25%+2.34%) were larger than that in control group(5.88%+ 1.46%) , P<0.01. The numbers of apoptotic HSCs in normal livers were small, but with the developing of liver fibrosis, the numbers of them increased. The positive cells of FAK, ERKi increased a lot, they were mainly situated in portal ducts, fiber septa and around the bile ducts , vascular endothelial cells andperisinusoidal cells. ERKi also existed in hepatocytes. Both FAK and ERK1 correlated with a -SMA positively, r value was 0.963 and 0.958 respectively, P<0.05 FAK ERK1 mRNA expressed in normal rat livers as well, they were up-regulated at day 2 and hour 6 after operation and the levels of them...
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