The Role Of Mitochondrial NIX Protein In Experimental Hepatic Fibrosis Inhibition By Ursodeoxycholic Acid

Objectives: After the damage of the pathogenic factors,the liver develops liver cirrhosis mainly through hepatic fibrosis.There are many complications of advanced liver cirrhosis,high cancer rate,and high mortality rate,which seriously endanger human health.The main pathogenesis of hepatic fibrosis is excessive diffuse deposition of extracellular matrix(ECM).Previous reports that activated hepatic stellate cells(HSCs)are the main cells that produce ECM.Ursodeoxycholic acid(UDCA)has an anti-fibrotic effect,but the specific pharmacological mechanism remains unclear.The pathogenesis of multiple system diseases is closely related to mitochondrial function,and mitochondrial NIP3-like protein X(NIX)may be involved in the progression of hepatic fibrosis.The purpose of this experiment was to investigate the relationship between the expression of mitochondrial NIX protein and the inhibition of experimental hepatic fibrosis by UDCA.Methods: The HSC-LX2 cell line was used for in vitro experiment,and the liver tissue of a rat model of hepatic fibrosis induced by CCl4 was used for in vivo experiment.Western blot(WB)was used to detect the difference of expression of ?-SMA and NIX between LX2 cells in each groups.Real-time quantitative PCR(qRT-PCR)was used to compared the expression of COL1A2 mRNA in LX2 cells and differential expression of COL1A2 mRNA and NIX mRNA in Liver tissue.Apoptosis of LX2 cells in groups was detected by flow cytometry.Masson staining assesses liver fibrosis in rats.Results: The expression of ?-SMA,NIX,COL1 mRNA in TGF?1 activated LX-2 cells were increased by 60.9%,51.0%,and 185.2% compared with the control group respectively.UDCA inhibited the expression of ?-SMA and COL1A2 mRNA after activation of TGF?1 in LX2 cells.The inhibition rates of UDCA were 55.6% and 86.1%,which was positively correlated with the significant down-regulation of NIX expression.UDCA promote apoptosis of LX2 cells after TGF?1 activation.In vivo experiments further showed that after UDCA treatment of CCI4-induced liver fibrosis in rats can significantly inhibit the formation of collagen in the liver,compared with the model group at the same time inhibition of NIX mRNA,COL1A2 mRNA expression,inhibition rates were 70.0%,47.9 %.Conclusions: The progression of hepatic fibrosis has increased the expression of NIX protein.UDCA down-regulates the expression of mitochondrial NIX protein and exerts its anti-fibrotic effect,which may provide a new pharmacological mechanism for UDCA treatment of hepatic fibrosis.