Sensitive detection of hepatocellular injury in chronic hepatitis C patients with circulating hepatocyte-derived microRNA-122

As chronic hepatitis C patients with progressive disease can present themselves with normal ALT levels, more sensitive biomarkers are needed. MicroRNAs are newly discovered small noncoding RNAs that are stable and detectable in the circulation. We aimed to investigate the association between hepatocyte-derived microRNAs in serum and liver injury in patients with chronic hepatitis C. The hepatocyte-derived miR-122 and miR-192 were analysed in sera of 102 chronic HCV-infected patients and 24 healthy controls. Serum levels of miR-122 and miR-192 correlated strongly with ALT (R=0.67 and R=0.65, respectively, P<0.001 for both). Median levels of miR-122 and miR-192 in HCV-infected patients were 23 times and 8 times higher as in healthy controls (P<0.001 for both). Even within the HCV-infected patients with a normal ALT (n=38), the levels of miR-122 and miR-192 were 12 times and 4 times higher compared with healthy controls (P<0.001 for both). Multivariate logistic regression analyses showed that only miR-122 was a significant predictor of the presence of chronic HCV infection (P=0.026). Importantly, miR-122 was also superior in discriminating chronic HCV-infected patients with a normal ALT from healthy controls compared with the ALT level (AUC=0.97 vs AUC=0.78, P =0.007). In conclusion, our study confirmed that liver injury is associated with high levels of hepatocyte-derived microRNAs in circulation and demonstrated that in particular miR-122 is a sensitive marker to distinguish chronic hepatitis C patients from healthy controls. More sensitive blood markers would benefit especially those patients with minor levels of hepatocellular injury, who are not identified by current screening with ALT testing.