miR-197 Expression in Peripheral Blood Mononuclear Cells from Hepatitis B Virus-Infected Patients

BACKGROUND/AIMS: This study aimed to investigate the microRNA (miRNA) expression profiles in peripheral blood mononuclear cell (PBMC) of hepatitis B virus (HBV)-infected patients with different clinical manifestations and to analyze the function of miR-197. METHODS: PBMC miRNA expression profiles in 51 healthy controls, 70 chronic asymptomatic carriers, 107 chronic hepatitis B patients, and 76 HBV-related acute on chronic liver failure patients were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). miR-197 mimic and inhibitor were transfected in THP-1 cells. qRT-PCR and ELISA for interleukin (IL)-18 mRNA and protein levels were performed, respectively. RESULTS: The microarray analysis revealed that 17 PBMC miRNA expression profiles (12 miRNAs downregulated and five miRNAs upregulated) differed significantly in HBV-induced liver disease patients presenting with various symptoms. The qRT-PCR results suggested that the PBMC miR-197 levels regularly decreased as the severity of liver disease symptoms became aggravated. IL-18, a key regulator in inflammation and immunity, was inversely correlated with miR-197 levels. Bioinformatic analysis indicated that IL-18 was a target of miR-197. Exogenous expression of miR-197 could significantly repress IL-18 expression at both the mRNA and protein levels in THP-1 cells. CONCLUSIONS: We concluded that multiple PBMC miRNAs had differential expression profiles during HBV infection and that miR-197 may play an important role in the reactivation of liver inflammation by targeting IL-18.