The Effect And Mechanism Of 20-HETE On Liver Fibrosis Through The TGF-β/Smad Signaling Pathway

In the human body,cytochrome P450-4A enzyme（Cytochrome P450 4A,CYP4A enzyme）can promote the metabolism of free arachidonic acid（Arachidonic acid,AA）to produce 20-hydroxy-eicosatetraenoic acid（20-Hydroxyeicosatetraenoic acid,20-HETE）.20-HETE is a vasoconstrictor in pharmacological studies,and it has been shown to promote TGF secretion and vascular epithelial cell fibrosis.According to related articles,researchers found that the AA content in the serum of non-alcoholic steatohepatitis（Nonalcoholic steatohepatitis,NASH）patients was significantly higher than the AA content in the serum of healthy people.The more severe the liver cirrhosis,the more obvious the increase of 20-HETE metabolite 20-carboxyarachidonic acid（20-Carboxy-Arachidonic Acid,20-COOH-AA）.The CYP4A enzyme induces an increase in 20-HETE.20-HETE stimulates the increase of TGF-βto activate the Smad pathway to activate hepatic stellate cells（Hepatic stellate cells,HSC）.TGF-β1 activates the Smad signaling protein to phosphorylate it,and the phosphorylated P-Smad3 conducts fibrotic signals,thereby causing fibrosis Over-expression and synthesis of collagen and other genes.After a lot of research,it can be proved that the disorder of TGF-β1/Smad signaling pathway is an important mechanism that promotes liver fibrosis.After HSC is activated,cell proliferation begins,the cell morphology changes,and it becomes myofibroblasts.The abnormal deposition of extracellular matrix（Excessive extracellular matrix,ECM）leads to the increase of proteins,mainly including collagen（Collagen type I alpha 1,COL1A1）and smooth muscle agonist protein（α-smooth muscle actin,α-SMA）,etc.These ECMs exist in large amounts in the extracellular space,and they accumulate slowly over time,and the final quantitative changes produce qualitative changes,leading to the production of liver fibrosis.Objective:To review the literature and conduct literature analysis,through in vivo and in vitro experiments,to study the effect of 20-HETE induced by CYP4A enzyme on liver fibrosis through the TGF-β/Smad3 pathway.Method:For a more in-depth study,the experiment was performed in cultured HSC-T6 cells and C57BL/6 mice with liver fibrosis induced by carbon tetrachloride（Carbon tetrachloride,CCl₄）.By screening the effects of different concentrations of20-HETE on HSC-T6 cells,the study found that 20-HETE activates the TGF-β/Smad3pathway,thereby increasing the protein expression ofα-SMA and COL1A1 at a certain concentration.In in vitro cell experiments,CYP4A enzyme agonists and inhibitors were added to the cells,and the cells were transfected to study the effect of CYP4A enzyme on HSC-T6 cells.Then,in vivo experiments of lentiviral silencing and CYP4A14 gene overexpression were used to study its effect.The role of liver fibrosis in mice.Results:CYP4A enzyme can induce an increase in 20-HETE.20-HETE activates the hepatic stellate cell（HSC）by stimulating the increase of TGF-βto activate the Smad pathway.TGF-β1 activates the Smad signaling protein to phosphorylate it,causing abnormal deposition of the extracellular matrix ECM and leading to the increase of protein.It mainly includes collagen（COL1A1）and smooth muscle agonist protein（α-SMA）.The overexpression of CYP4A in vitro promotes HSC activation and has the effect of promoting fibrosis;injection of lentivirus of CYP4A14 gene in mice can increase the content of 20-HETE in serum and aggravate liver fibrosis in mice.Conclusion:20-HETE activates HSCs through TGF-β/Smad pathway to promote fibrosis.Exploring the relationship between liver fibrosis and CYP4A enzyme and its arachidonic acid metabolite 20-HETE reveals a new link in the pathological mechanism of liver fibrosis.The study of CYP4A/20-HETE’s mechanism of promoting liver fibrosis provides a new target for anti-liver fibrosis treatment.