Abstract: AIM: To investigate the effects of microRNA let-7a on Con A-induced hepatitis.METHODS: 24 BALB/c mice were randomly divided into model group and let-7a treatment group. The liver hepatitis models were established by the tail vein injection of Con A. Mice was infected with a lentiviral vector containing the let-7a sequence 7 days before Con A treatment. The plasma alanine transaminase (ALT) activities were measured with a 7170 Hitachi automatic analyzer. The serum TNF-α, IL-6 and IFN-γ were determined with enzyme-linked immunosorbent assay (ELISA) kits. The liver samples were fixed in 10% formalin, embedded in paraffin, sectioned and then stained with hematoxylin and eosin for histological examinations.RESULTS: The serum ALT level was significantly decreased in the let-7a infected-mice compared to the control mice (P<0.001). Pretreatment with let-7a consistently reduced the extent of liver damage, as evidenced by the decreased infiltrated lymphocytes (P<0.05) and the limited number of necrotic lesions in these mice (P<0.01). Furthermore, let-7a significantly improved the survival rate after Con A treatment. It was accompanied by a significant decreased level of inflammatory cytokines as TNF-α, IL-6 and IFN-γ in the serum.CONCLUSION: MicroRNA let-7a ameliorates Con A-induced hepatitis. It may represent as a novel therapeutic strategy in treating immune-mediated inflammatory hepatitis.

Key words: MicroRNA, Let-7a, Hepatitis