Micro RNA-122 and the Clinical Course of Patients With Chronic Hepatitis C

Combination therapy with peginterferon plus ribavirin has become the current standard of care for chronic hepatitis C (CHC) patients, with an overall sustained virologic response (SVR) rate of 54-63%. Based on the ample evidence, a 48-week course of peginterferon plus weight-based ribavirin therapy is widely recommended to treat HCV genotype 1 infection in different parts of the world. Despite the increased SVR rates with the improved medical therapies, about 25-50% and 10-20% of HCV genotype 1 and HCV genotype 2/3 patients may experience relapse after the cessation of therapy with undetectable HCV viremia at the end of treatment. Moreover, combination therapy is costly and may cause various adverse events. Therefore, individualized therapy based on outcome analysis should be adopted to save medical cost as well as to lessen inadequate treatment. Few studies are aimed to evaluate the host responses of micro RNA regulation during interferon-based therapy and its relationships to the overall treatment responses. Micro RNA (miRNA) is a single-stand RNA composed of 21-23 nucleotides, which may regulate the function of messenger RNA (mRNA). The regulating mechanisms involving micro RNA between the hosts and the HCV virus include (1) auto-regulation of HCV mRNA by HCV miRNA; (2) regulation of host mRNA by HCV miRNA; and (3) regulation of HCV mRNA by host miRNA. MiR-122 is the abundant liver-specific miRNA which is crucial for efficient HCV replication in culture Huh7 cells stably expressing HCV replicons. Recently, an in vivo study for hepatic miR-122 of 42 patients with CHC who received IFN-based therapy showed that patients who did not respond to IFN therapy had markedly decreased pretreatment miR-122 levels. Although miR-122 is abundant in the liver, liver biopsy is still considered an invasive procedure, which prevents its widespread use in routine clinical practice. The miRNA can be detected in the sera and is stable after 24 hours of room temperature store or repeated freezing and de-freezing. The serum miR-122 levels can reflect the severity of liver injuries in a rat acetaminophen toxicity model. Because miR-122 is liver specific and the miRNA is stable in the sera, the investigators aimed to evaluate the role of serum and hepatic miR-122 on the viral kinetics and the treatment responses and in HCV patients receiving peginterferon and ribavirin combination therapy.