Therapeutic effects of CCAAT/enhancer-binding protein α gene on liver fibrosis in mice / 中华消化杂志

ABSTRACT

Objective To investigate the difference of CCAAT/enhancer-binding protein α (C/EBP-α) gene induced apoptosis between hepatocytes and hepatic stellate cells (HSC) in mice with liver fibrosis.Methods Sixty BALB/c mice were evenly divided into normal group,model group,treatment group,blank control group and negative control group,12 mice in each group.Except the mice of normal control group,the mice of other groups were treated with intraperitoneal injection of CCl4 to establish liver fibrosis mice model.Mice of treatment group,blank control group and negative control group were administrated with C/EBP-α carried adenovirus (Ad-C/EBP-α),phosphate buffered solution and empty vector of adenovirus (Ad-EGFP) respectively through tail vein for the first week.The expression of C/EBP-α and α-smooth muscle actin (α-SMA) was detected by immunohistochemistry method.Sinusoidal endothelial structure of peri-portal regions and far from portal regions was observed by transmission electron microscope (TEM).Terminal dexynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was applied to detect apoptosis of cells in liver tissue.The degree of liver fibrosis in mice was determined with sirius red staining and hydroxyproline content measurement.Single factor variance analysis was performed for comparison among multiple groups,and t test was used for comparison between two groups.Results C/EBP-α was expressed in nucleus of hepatocyte in normal control group mice.The expression decreased in model group,blank control group and negative control group.However,the expression of C/EBP-α of treatment group increased,and mainly expressed in cells located in perisinusoidal and perivascular.Hepatic sinusoids was distorted,blood vessel wall thickened.Hepatocyte degeneration and lots of lipid droplets was found in model group,blank control group and negative control group.The thicken degree of endothelial layer of blood vessel of treatment group was lower than that of model group.The percentage of sirius red positive cells of normal group,model group,treatment group,blank control group and negative control group was (0.10±0.03)％,(5.81±0.32)％,(2.32±0.45)％,(6.34± 0.81)％ and (6.10± 0.92)％,respectively; content of hydroxyproline was (0.07±0.00) μg/mg,(0.69 ± 0.10) μg/mg,(0.19±0.06) μg/mg,(0.56±0.03) μg/mg and (0.64±0.08) μg/mg,respectively; the percentage of α-SMA positive cells was (0.50 ±0.03)％,(5.30 ± 0.52)％,(2.15 ± 0.29)％,(5.53 ± 0.43) ％ and (5.42 ± 0.25) ％,respectively; the number of TUNEL positive cells was (0.25 ± 0.08),(0.15±0.02),(7.10±1.53),(0.13±0.03) and (0.18±0.07),respectively.The differences between the groups were statistically significant (F=113.74,148.29,292.43 and 140.25,all P＜0.05).The difference between normal group and model group,between model group and treatment group,between treatment group and blank control group,between treatment group and negative control group were statistically significant (tarirus positive cell =-52.54,-16.20,-10.60 and-7.99,thydroxyproline content =-168.00,11.53,11.07 and 12.54,ta SMA pusitive cells-24.77,-13.82,15.94 and 18.37,tTUNEL positive cells =3.26,-11.91,-11.95 and-11.88,all P＜ 0.05),there was no statistically significant difference between model group and blank control group,between model group and negative control group (both P＞0.05).TUNEL positive cells mainly located in perisinusoidal and perivascular of liver in mice,which was consistent with the distribution of α-SMA-positive cells.Conclusion C/EBP-α could effectively relieve CCl4 induced liver fibrosis in mice mainly through inducing HSC apoptosis,however no apoptosis effect on hepatocytes.