Study On The Correlation Between Non-alcoholic Fatty Liver Disease And Early Renal Damage

Objectives:The NASH model of SD rats induced by high fat diet was established and the renal lesions of NASH related rats were observed,so as to explore the correlation between non-alcoholic fatty liver disease and early renal damage.Part I Animal experiments Research objects:Twenty healthy male SD rats aged 4-5 weeks and weighing 80-120 g were selected.Methods:(1)Twenty SD rats were numbered successively,and 20 two-digit random numbers were selected from the random number table and sorted.Among them,the 13 rats corresponding to rank 1 to 13 were assigned to the experimental group(group B)and given high-fat diet and free drinking water.At the end of the 4th,8th and 12 th week of the experiment,2 of the 13 rats in group B were randomly killed,and the liver tissues were extracted for HE staining,and the non-alcoholic steatohepatitis was observed under microscope.The model of non-alcoholic steatohepatitis was successfully established at the end of the 12 th week.(2)The other 7 SD rats were used as the control group(group A)and given normal diet and free water.At the end of the 12 week experiment,SD rats in group A and group B were all killed after 12 hours of fasting without water.(3)After the separation of liver and kidney tissues of SD rats,samples were collected,embedded,sections were made and observed under microscope.(4)The lower venous blood of SD rats was extracted,the supernatant was separated,and the changes of relevant serological indexes(including ALT,AST,GGT,LDL,TG,TC,Glu,and INS)were analyzed.Results:(1)Compared with the control group,the high fat group had higher liver pathological scores,serum ALT,GGT,LDL,TG,TC,Glu,INS,HOMA-IR(P < 0.05),higher AST and renal average optical density AO value,but no statistical differences(P >0.05).(2)From the 4th week to the 12 th week,the histomathological changes of the liver in the high-fat group were as follows: hepatic lobule structure was gradually destroyed,small fat vacuoles in the cytoplasm of liver cells were gradually transformed into large fat vacuoles,and inflammatory cells were gradually infiltrated in the portal area.At the end of the 12 th week,pathological changes of the kidney in the high fat group were as follows: increased PAS positive substances,increased glomerular volume,thickened basement membrane of glomerular capillaries,disorganized capillary loops,and hyperplasia of mesangial region;The epithelial cells of renal tubules are swollen and some lumen are narrow.Immunohistochemistry of renal tissue in high fat group: Desmin expression in glomerular podocytes was enhanced.Conclusion:High fat diet induced nonalcoholic steatohepatitis in SD rat model resulted in renal glomerular enlargement,capillary basement membrane thickening,mesangial hyperplasia,and podocyte injury.Part II Clinical Trials Objects:Patients with fatty liver aged between 18 and 60 who were admitted to the Affiliated Hospital of Yan ’an University from October 2018 to February 2021 were selected.Healthy subjects were selected as the control group.A total of 249 eligible subjects were included,including 120 in the NAFLD group(60 males and 61 females)and 129 in the healthy control group(68 males and 61 females).Methods:(1)120 NAFLD patients diagnosed by Fibroscan and meeting the inclusion criteria were selected as the experimental group,and 129 healthy people who had physical examination in our hospital and meeting the inclusion criteria were selected as the control group.(2)The general information of the included subjects and their laboratory biochemical indicators were recorded,including age,gender,body mass index(BMI),waist circumference(WC)and blood pressure(SBP/DBP).The biochemical analysis indexes of each laboratory were all obtained from venous blood samples collected in the morning after 8 hours of fasting.Including aspartate aminotransferase(AST),alanine aminotransferase(ALT),alkaline phosphatase(ALP)and gamma glutamyl transpeptidase(GGT),total bilirubin(TB),total cholesterol(TC),triglyceride(TG),high-density lipoprotein(HDL),low density lipoprotein(LDL),urea nitrogen(BUN),creatinine(Cr),β2 microglobulin(β2-MG),cystatin C(Cys-C),retinol binding protein(RBP),estimated glomerular filtration rate(e GFR),uric acid(UA),fasting plasma glucose(FPG).(3)Analyze whether there are differences in general baseline data and various laboratory biochemical indicators between the two groups.Results:(1)A total of 120 patients with NAFLD were included,including 60 males(50%)and 60 females(50%),10(8.3%)with a BMI < 23kg/m2,and an average age of41.62±13.88 years.In the control group of 129 patients,there were 68 males(52.7%)and61 females(47.3%),with an average age of 41.63±11.89 years.Compared with the control group,the NAFLD group had higher levels of BMI and SBP(P < 0.05).The WC of NAFLD group was higher than that of normal control group(P > 0.05).(2)Compared with the control group,AST,ALT,GGT and ALP were higher in NAFLD group(P < 0.05),TB was also higher in NAFLD group,but there was no statistical differences(P > 0.05).(3)Compared with the control group,NAFLD group had higher TG,TC,LDL,and lower HDL.There were differences in TG and HDL(P < 0.05),but no statistical differences in TC and LDL(P > 0.05).(4)Compared with renal function,UA,Cr,Cys-C,β2-MG,BUN and RBP in NAFLD group were higher than those in control group,while e GFR was lower than that in control group.There were significant differences in UA,Cr,Cys-C,β2-MG and e GFR in NAFLD group(P < 0.05),but no significant differences in BUN and RBP(P > 0.05).(5)Compared with the control group,FPG and LSM were higher in the NAFLD group(P < 0.05).(6)Spearman correlation analysis of all influencing factors with e GFR,Cys-C andβ2-MG showed that:(1)e GFR was negatively correlated with BMI,AST,ALT,ALP,GGT,TG,FPG,Cr,UA,Cys-C and LSM,and Cr and BMI had the strongest correlation with e GFR,with correlation coefficients of-0.763 and-0.428,respectively.HDL was positively correlated with e GFR.(2)Cys-C was positively correlated with BMI,FPG,β2-MG,AST,ALT,ALP,GGT,TG and LSM;e GFR and HDL were negatively correlated with Cys-C.(3)β2-MG was positively correlated with BMI,AST,ALP,GGT,TG,Cys-C and LSM.HDL was negatively correlated with β2-MG.(7)Multivariate logistic regression analysis results showed that Cys-C,TG,FPG,Cr,UA and severity of liver fibrosis were risk factors for early renal damage.After adjusting for confounding factors,severity of liver fibrosis was still a risk factor for early renal damage(OR= 1.405(1.085～1.821),P=0.01).Conclusion:Non-alcoholic fatty liver disease is closely related to early renal damage,and the severity of liver fibrosis is an independent risk factor for early renal damage.