Serum miR-122 as a biomarker of necroinflammation in patients with chronic hepatitis C virus infection.

Abstract

The liver contains large amounts of microRNA-122 (miR-122), whereas other tissues contain only marginal amounts of this miRNA. MicroRNAs have also been found to circulate in the blood in a cell-free form; their potential as readily accessible disease markers is currently evaluated. Here, we investigated if the serum levels of miR-122 might be useful as disease parameter in patients with chronic hepatitis C virus (HCV) infection. RNA was extracted from sera of patients with chronic HCV infection (CHC) and healthy controls and was analyzed for miR-22 content by quantitative real-time reverse-transcription polymerase chain reaction. miR-122 serum levels were correlated with standard parameters of liver function. Liver biopsies from the same patients were examined for the histologic activity index (HAI) and the degree of fibrosis. Sera from patients with CHC contained higher levels of miR-122 than sera from healthy controls. Serum miR-122 levels correlated well with markers of liver inflammatory activity, that is, the serum levels of alanine leucine transaminase (ALT) and aspartate transaminase, and the HAI score. In patients with persistently normal ALT levels, serum miR-122 levels did not differ from healthy controls. There was no correlation of serum miR-122 levels with serum albumin, international normalized ratio, liver fibrosis, or serum HCV RNA. The serum level of miR-122 strongly correlates with serum ALT activity and with necroinflammatory activity in patients with CHC and elevated ALT levels, but not with fibrosis stage and functional capacity of the liver.