The Relationship Between Endoplasmic Reticulum Stress And TRAIL In Apoptosis Of Hepatic Stellate T6Cells

Liver fibrosis is caused by a variety of pathogenic factors of intrahepatic connective tissue dysplasia, resulting in the excessive deposition of the pathological process of diffuse intrahepatic diffuse extracellular matrix. It is the middle of the development of chronic liver disease to cirrhosis. With the development of liver disease, liver cell necrosis, diffuse nodular regeneration of liver parenchyma and deposition of collagen fibers which ultimately caused the liver structural changes, eventually lead to cirrhosis. Recent studies have found that liver fibrosis can be reversed after the removal of the damage factor, expressed as reduced collagen deposition, degree of liver pathology and liver function recovery. Hepatic stellate cells play an important role in liver damage and repair, induced apoptosis of hepatic stellate cells is one important way to promote the recovery of liver fibrosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a tumor necrosis factor family members, which induced by a variety of tumor cell apoptosis selectively. Our previously study found that KC and activated HSC by inducing TRAIL and other apoptosis-stimulating factor to promote HSC apoptosis in liver fibrosis recovery period, promoting the degradation of ECM, thereby promoting the reversal of liver fibrosis.The endoplasmic reticulum stress can mediated apoptosis signaling pathway following the death receptor activation and mitochondrial damage. In hypoxia, oxidative stress, calcium homeostasis in the endoplasmic reticulum unfolded protein will be significantly increased, and when beyond the handling capacity of the endoplasmic reticulum, the cell activation-related signaling cascades to respond to changes in external conditions in order to restore endoplasmic reticulum protein folding environment, start the endoplasmic reticulum stress disorder caused by the physiological functions of the endoplasmic reticulum. Endoplasmic reticulum stress apoptosis can induce a variety of apoptosis as a new cell signaling pathway. Numerous studies found that the endoplasmic reticulum stress and the occurrence of a variety of liver diseases are closely related.Endoplasmic reticulum stress-related protein in liver fibrosis model and its reversal in how the changes have not been reported. The experiment by using CCl4induced animal models of hepatic fibrosis, research endoplasmic reticulum stress-related protein liver fibrosis in the course of dynamic changes, and explore the role of endoplasmic reticulum stress in liver fibrosis in the course of disease. Based on in vitro cultured rat hepatic stellate cells (HSC-T6) to further explore the endoplasmic reticulum stress and the relationship between TRAIL in apoptosis of rat hepatic stellate cells, the study includes the following sections:1.Dynamic expression changes of endoplasmic reticulum stress-related proteins in a rat liver fibrosis modelIn this study, CCl4was subcutaneous injection of12weeks in the rat liver fibrosis model. The pathology HE staining and VG collagen staining showed that the model of rat liver tissue can be seen a large number of collagen deposition extended to lobular edge, thickening of the fibrous septa and have a large number of fat vacuoles. Stop injecting by CCl44weeks,8weeks, significantly reduced the degree of liver tissue fiber deposition, fat vacuoles reduce the fiber interval smaller and narrower. Indicated that liver fibrosis model was established successfully, stop CCl4subcutaneous injection for4weeks, after8weeks, hepatic fibrosis in rats have a spontaneous tendency of reversal.Immunohistochemical detection of endoplasmic reticulum stress-related protein expression found that endoplasmic reticulum stress markers protein CHOP and GRP78cytoplasm slightly stained in normal liver tissue. In the hepatic fibrosis model group, CHOP and GRP78coloring significantly deepened, the positive expression was significantly higher than the normal group, suggesting that the endoplasmic reticulum stress response is closely related to hepatic fibrosis in rats. Further observed that to stop injecting by CCl44weeks,8weeks, hepatic fibrosis into the reversal of convalescence, this time CHOP and GRP78positive expression decreases compared with model group, the staining Dodge, shown along with the reversal of liver fibrosis, the degree of ER stress response reduced.RT-PCR test results also show that CHOP and GRP78mRNA levels in the liver fibrosis model of significantly up-regulated. Compared with model group, with the recovery of4and8weeks of fibrosis severity reduced, CHOP snd GRP78mRNA expression decreased. It is demonstrate that liver fibrosis endoplasmic induce reticulum stress. Endoplasmic reticulum stress involved in the occurrence and the reversal of hepatic fibrosis in rats, plays an important role in this process. Western blot results are consistent with the above. These results suggest that endoplasmic reticulum stress exist in the process of hepatic fibrosis in rats, there is a close contact may be related to the occurrence, development and reversal of liver fibrosis.2. In vitro study of the relationship between endoplasmic reticulum stress and TRAIL in the rat HSC-T6cells apoptosis and its mechanismIn vitro rat hepatic stellate cells HSC-T6, take Thapsigargin (TG) as the endoplasmic reticulum stress-inducing agents, ursodeoxycholic acid (UDCA) for the endoplasmic reticulum stress inhibitors, SP600125as a INK inhibitor, application of small interference RNA to silence CHOP gene. Flow cytometry found that with the TG concentration (1μM,2μM,4μM,8μM,16μM) increasing, can induce HSC-T6apoptosis; RT-PCR and Western blot showed that the endoplasmic reticulum stress protein marker CHOP induction TARIL receptor DR5is upregulated.Furthermore, siCHOP and INK inhibitor SP600125can attenuate DR5expression in the HSC cells. Indicated that within the endoplasmic reticulum stress and TRAIL in the existence of certain links in the mechanism of apoptosis in HSC-T6. CHOP and INK may be a potential factor regulating DR5expression regulation plays an important role for the TRAIL receptor DR5.In summary, the datas show that the endoplasmic reticulum stress involved in the process of hepatic fibrosis in rats and played an important role in this process. It is prove that TG can induce the HSC-T6cells the endoplasmic reticulum stress cause apoptosis; found that endoplasmic reticulum stress links with TRAIL in the mechanism of apoptosis in HSC-T6. CHOP and INK are two potential factors regulating DR5expression regulation plays an important role for the TRAIL death receptor DR5.