The Effect Of Leukocyte Derived Chemokine 2(LECT2) On Liver Lipotoxicity

Background and aimNonalcoholic fatty liver disease(Nonalcoholic fatty liver disease,NAFLD)is a clinical pathological syndrome characterized by the accumulation of diffuse large vacuoles of fat in the liver not caused by alcohol use and other clear etiologies,NAFLD is the most common chronic liver disorder in china.An increasing number of studies suggest that the important mechanism of Nonalcoholic steatohepatitis(NASH)is lipotoxic injury,but the molecular level mediated mechanism of substance and pathway is not yet well understood.Leukocyte cell-derived chemotaxin 2(LECT2)is a kind of neutophil chemotactic factor,it is also considered as a member of the liver factor in recent years,it can directly affect the carbohydrate and fat metabolism by regulating inflammation and insulin signaling cascade system.We examine the effect of LECT2 in the pathogenesis of nonalcoholic fatty liver by establishing a cell model of hepatic lipotoxicity.Materials and methodsHepG2 cells were treated with palmitic acid(PA),after 24 hours treatment,the cell viability,cytotoxicity and apoptosis were respectively detected by CCK8,LDH and Caspase3 activity assay kit.The expression level of TNF-a in cell supernatant was measured by ELISA method.The expression level of LECT2 in cells was measured by fluorescence quantitative PCR(q-PCR).Small interference RNA(Si-RNA)technique was used to knockout LECT2 and NF-κB expression,Western blot(WB)and q-PCR was used to detect the efficiency.The broad-spectrum apoptosis inhibitor Z-VAD was used to inhibit apoptosis.The WB method was used to detect the activation of the NF-κB pathway.ResultsHepG2 cells were treated with PA-containing medium for 24 hours,the cell activity decreased,the cell cytotoxicity and cell apoptosis increased,the level of cytokines tumor necrosis factor(TNF-alpha,TNF-a)increased.The mRNA level of LECT2 significantly increased after PA stimulation in HepG2 cells.Under the condition of lipid toxicity,the cell activity of the LECT2 knockout group was further decreased compared with the control group,and the cytotoxicity was further enhanced,accompanied by a further increase in apoptosis.When inhibitor Z-VAD was used to inhibit apoptosis,the increase of liver cell lipotoxicity caused by knocking down the expression of LECT2 was disappeared.We explored the possible cellular pathways of the phenomenon:it was found that in the lipotoxic state,the expression of NF-κB pathway was significantly activated after knockout LECT2,and it could partially reduce the lipotoxicity of liver cells when knockout LECT2 and P65 at the same time compared with LECT2 knockout alone.ConclusionsLECT2 has protective effect on liver lipotoxicity.It can inhibit the apoptosis induced by inhibiting NF-κB dependent pathway,thereby protecting liver cells from lipid toxicity.