Abstract:

Objective To investigate the clinical role of serum cathepsin D（CTSD） in non-alcoholic fatty liver disease（NAFLD）. Methods A total of 356 NAFLD patients were enrolled and classified into 3 groups according to ultrasound diagnosis,which were mild group（146 patients）,moderate group（113 patients） and advanced group（97 patients）. Totally,300 healthy subjects were enrolled as control group. Serum levels of CTSD,alanine aminotransferase（ALT）,aspartate aminotransferase（AST）,gamma-glutamyltransferase（GGT）,triglyceride（TG）,total cholesterol（TC） and low-density lipoprotein cholesterol（LDL-C） were determined. Pearson correlation analysis and Spearman correlation analysis were used to assess the correlation between each indicator and the severity of NAFLD. Receiver operating characteristic（ROC） curve was used to evaluate the diagnosis value of these indicators. Results Serum levels of ALT,TC,TG,LDL-C and CTSD in NAFLD group were higher than those in control group（P<0.01）,which had statistical significance among NAFLD groups（P<0.01）. Compared with control group,serum levels of AST and GGT were increased in NAFLD group （P<0.01）,and those in advanced group were higher than those in moderate group（P<0.01）,while there was no statistical significance between control and mild groups（P>0.05）. Serum CTSD was positively correlated with the severity of NAFLD （r_s=0.800 5,P<0.000 1）,ALT（r=0.541,P<0.01）,TC（r=0.662,P<0.01） and LDL-C（r=0.571,P<0.01）. ROC curve analysis showed that the areas under curves（AUC） of CTSD,ALT and GGT in the diagnosis of NAFLD were 0.940,0.822 and 0.627,respectively. The optimal cut-off values were 12.67 pg/mL,38.00 U/L and 53.00 U/L,respectively. The sensitivities were 76.97%,51.69% and 34.55%,and the specificities were 91.33%,93.00% and 92.33%,respectively. The AUC of CTSD combined with ALT determination in the diagnosis of NAFLD was 0.960,the sensitivity was 88.48%,and the specificity was 90.00%. Conclusions Serum level of CTSD is correlated with the severity of NAFLD,and it can be used as a biomarker for the early diagnosis and staging of NAFLD.

Key words: Cathepsin D, Non-alcoholic fatty liver disease, Biomarker