Serum levels of caspase-cleaved cytokeratin 18 (CK18-Asp396) predict severity of liver disease in chronic hepatitis B

BACKGROUND AND AIM Caspase-cleaved cytokeratin 18 (CK18-Asp396) is a potential clinically useful biomarker in liver disease as it is released from hepatocytes during apoptosis. In this study, we investigated serum CK18-Asp396 levels in chronic hepatitis B (CHB). PATIENTS AND METHODS Overall, 163 patients with CHB were included. Serum CK18-Asp396 levels were determined by enzyme-linked immunosorbent assay (ELISA), and results were related to steatosis grade, histological activity index, inflammation score, and METAVIR fibrosis grade as well as to viral load, serum levels of liver enzymes, and albumin. Receiver operating characteristic analysis was used to evaluate the diagnostic performance of serum CK18-Asp396 levels for assessing disease activity. RESULTS A higher level of serum CK 18 concentrations was found in patients with significant inflammation vs no significant inflammation (378.5 [interquartile range {IQR}: 173.2-629.6] vs 137.3 [87.5-197.7], P < 0.05; approximately threefold increase) and in patients with significant fibrosis vs no significant fibrosis (177.8 [IQR: 120.8-519.1] vs 142.7 [IQR: 88.8-214.4], P < 0.05; 1.25-fold increase). There was no differential CK 18 level by degree of steatosis. CK 18 was an independent predictor of significant inflammation with an 82% specificity and a 94% negative predictive value. We found the strongest correlation of CK 18 with alanine aminotransferase and aspartate aminotransferase (both r = 0.52; P < 0.001), but less with albumin (r = -0.24; P < 0.05) and viral load (log) (r = 0.19; P < 0.05). CONCLUSION CHB appears to be accompanied by continuous high levels of hepatocyte apoptosis as judged from serum CK 18, suggesting that elimination of the infected compartment constitutes a defensive strategy against disease. Accordingly, CK 18 works as an independent predictor of significant inflammation with a high specificity.