Background: Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease is increasing in adults and children worldwide. Obesity, insulin resistance or diabetes type II, hyperlipidemia and hypertriglyceridemia plays a major role in the epidemiology of this disease. Cytokeratin 18 (CK-18) the major intermediate filament protein in the liver is a marker of increased hepatocyte apoptosis. The aim of this study was to determinate CK-18 level as a marker of hepatocyte apoptosis and paraoxonase as a biochemical marker for lipid peroxidation.

Methods: This case–control study was done on 51 subjects with confirmed NAFLD by ultrasound and 30 healthy individuals. CK-18 is proposed as a biomarker alternative cell death. The serum was used for measurement of the apoptosis-associated neo-epitope in the C-terminal domain of CK-18 by the M30-Apoptosense ELISA kit. The M30 detection antibody recognizes a neo-epitope mapped to positions 387 to 396 of CK18, so called CK18-Asp396 that is only revealed after caspase cleavage of the protein and is postulated as a selective biomarker of apoptosis. Serum PON1 activity was assayed using a synthetic substrate. Paraoxon substrate (diethyl-p nitrophenylphosphate), was deliberated using the increase of absorbance at 412 nm at 37 ◦C. 

Results: There were significant differences regarding serum cytokeratin 18 (p=0.005), paraoxonase activity (p=0.03), triglycerides (p=0.04) and low-density lipoprotein (p=0.04) between NAFLD and healthy subjects. Between CK-18 and paraoxonase with the early stages of fatty liver disease are associated.

Conclusion: This study suggests that serum levels of cytokeratin 18 can be useful in predicting non-alcoholic fatty liver disease. Paraoxonase activity (PON1) should be considered a biochemical marker of lipid peroxidation and the need for follow-up in patients with NAFLD

Keywords: Non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), Cytokeratin 18 (CK-18), Paraoxonases