| Objective: The level of serum resistin and the expression of resistin in the liver, and the correlation of them with insulin resistance(IR), alanine aminotransferase(ALT), tumor necrosis factor-α(TNF-α) and the histological manifestations of liver in patients with nonalcoholic fatty liver disease(NAFLD) were investigated, to reveal the effect of resistin on the pathogenesis of NAFLD and to provide theory basis for the prevention and therapy of this kind of disease.Methods: 47 NAFLD patients in our hospital from July 2006 to June 2007 were chosen in our study, consistent with the clinical diagnostic criteria revised by Fatty Liver and Alcoholic Liver Disease Study Group of the Chinese Liver Disease Association in February 2006. 16 patients were confirmed by liver biopsy. The patients were divided into two groups, nonalcoholic steatohepatitis(NASH) group and simple fatty liver group. There were 20 persons in the control group. 15 of them were healthy persons and 5 of them were persons who received resection of hemangiomas of liver.Serum ALT, fasting blood glucose (FBG), and fasting insulin (FINS) were measured using an Olympus AU2700 auto-biochemical analyzer and radio-immune assay respectively. Insulin resistance index was calculated according to homeostasis model assessment(HOMA) model, HOMA-IR=(FINS×FBG)/22.5. Enzyme-linked immunosorbent assay (ELISA) was used for quantitative measurement of serum resistin and TNF-αconcentration. Haematoxylin-eosin(HE) staining was used for the general pathologic observation of liver, and the percentage of steatotic hepatocytes was calculated. The activity of hepatic inflammation was determined by the histological scoring system designed and validated by Pathology Committee of the NASH Clinical Research Network in USA in 2005. Masson staining was used for the observation of hepatic fibrosis. Immunohistochemical staining (Power VisionTM method) was used to measure the expression of resistin andα-smooth muscle action(α-SMA) in the liver. The percentage of collagen and the expression of resistin was calculated by multifunctional pathological image analyzer (Beijing Aerospace University). The average area density(the percentage of positive area to statistical area) was calculated under 20 power object lens.SPSS 13.0 was used to process all data.Result: 1 BMI and biochemical indexes: The level of BMI and HOMA-IR of NASH group and simple fatty liver group was higher than that of control group(P <0.01), and there was no statistical difference between NASH group and simple fatty liver group(P >0.05). The level of serum ALT and TNF-αof NASH group was higher than that of simple fatty liver group and control group(p <0.01), and there was no statistical difference between simple fatty liver group and control group(P >0.05). The serum resistin concentration was different among the three groups. The serum resistin concentration of NASH group and simple fatty liver group was higher than that of control group(P <0.01), and serum resistin concentration of NASH group was higher than that of simple fatty liver group(P <0.01). 2 Pathologic changes: The hepatocytes of NAFLD patients presented modest to big bubble steatosis. There was different degree of inflammation and fibrosis in the liver of NASH patients. 3 The expression of resistin: Resistin expressed mainly in perisinusoidal cells, and in areas of inflammation and portal areas of the liver. The positive cells were brownish yellow. The relative quantity of resistin in liver of NASH group was remarkably higher compared with that of simple fatty liver group and control group(P <0.01), and there was no statistical difference between simple fatty liver group and control group(P >0.05). 4 Correlation analysis: In all patients, the serum resistin concentration correlated positively with the level of BMI, HOMA-IR, ALT and TNF-α(r =0.472, 0.481, 0.852, 0.790, P <0.01). In NAFLD patients who received liver biopsy, the relative quantity of resistin in the liver correlated positively with the level of serum resistin, ALT, TNF-α, HOMA-IR, and the degree of hepatic inflammation and fibrosis(r =0.932, 0.937, 0.806, 0.453, 0.968, 0.965, P <0.05 or <0.01). Stepwise multiple regression analysis showed that the increase of expression of resistin in the liver was an independent risk factor for hepatic inflammation. The regressive equation was Y=-0.151+96.124X1(Y: hepatic inflammation; X1: the relative quantity of resistin in the liver). The coefficient of determination (designated as R2) was 0.937. The increase of expression of resistin in the liver was closely correlated with hepatic fibrosis. The regressive equation was Y=-0.016+0.742X1+0.017X5(Y: hepatic fibrosis; X1: the relative quantity of resistin in the liver; X5: TNF-α). The coefficient of determination (designated as R2) was 0.968.Conclusion: 1 IR, obesity and TNF-αplayed important role in the development of NASH. 2 The serum resistin concentration of NASH group and simple fatty liver group was higher than that of control group, and the serum resistin concentration of NASH group was higher than that of simple fatty liver group, and the serum resistin concentration correlated positively with the level of BMI, HOMA-IR, ALT and TNF-α. Resistin might be a key cytokine in the pathogenesis of NAFLD. 3 Resistin expressed mainly in perisinusoidal cells, and areas of inflammation and portal areas of the liver. The relative quantity of resistin in liver of NASH patients was remarkably higher compared with that in simple steatotic liver and normal liver. The expression of resistin in the liver correlated positively with the level of serum resistin, TNF-α, ALT, HOMA-IR, and the degree of hepatic inflammation and hepatic fibrosis. Resistin expressed in the liver participated in the development of NAFLD. 4 The high expression of resistin in the liver was an independent risk factor of hepatic inflammation and correlated closely with hepatic fibrosis. |
