Abstract: Objective: To detect the expression levels of miR-194-5p and magnesium transporter protein1(MagT1) in peripheral blood mononuclear cells (PBMCs) of the patients with chronic hepatitis B virus(HBV) infection, and to investigate their possible clinical significances. Methods: The clinical materials of 40 healthy subjects (healthy control group), 40 cases of asymptomatic hepatitis B carriers(HBV carrier group), 40 patients with mild-moderate chronic hepatitis B (mild-moderate CHB group) and 40 patients with severe chronic hepatitis B (severe CHB group) were collected. The peripheral blood of the subjects in various groups was collected and the PBMCs were isolated by Ficoll-Hypaque density gradient centrifugation. The expression levels of miR-194-5p and MagT1 mRNA in PBMCs of the subjects in various groups were detected by RT-PCR assay, the expression levels of MagT1 protein in PBMCs of the subjects in various groups were detected by Western blotting method,the levels of Mg²⁺ in peripheral blood and PBMCs of the subjects in various groups were detected, and the expression levels of CD8+ T lymphocyte surface molecules programmed death receptor 1(PD-1) and natural killer cell receptor 2 group D molecule (NKG2D) in PBMCs of the subjects in various groups were analyzed by flow cytometry. The miR-194-5p mimic (miR-194-5p mimic group)and miR-NC(miR-NC group) were transfected into the 293T cells, and then the dual luciferase reporter gene assay was used to detect the luciferase activities in 293T cells in two groups. Results: Compared with healthy control group, the expression levels of MagT1 mRNA and protein, the expression levels of CD8+ T lymphocyte surface molecule NKG2D and the levels of Mg²⁺ in PBMCs of the patients in HBV carrier group, mild-moderate CHB group and severe CHB group were decreased(P<0.05),the expression levels of miR-194-5p mRNA in PBMCs and CD8+ T lymphocyte surface molecule PD-1 of the patients were increased(P<0.05).Compared with HBV carrier group and mild-moderate CHB group,the expression levels of MagT1 mRNA and protein, the expression level of CD8+ T lymphocyte surface molecule NKG2D and the level of Mg²⁺ in PBMCs of the patients in severe CHB group were decreased (P<0.05), and the expression levels of miR-194-5p mRNA in PBMCs and CD8+ T lymphocyte surface molecule PD-1 of the patients were increased (P<0.05).Compared with HBV carrier group, the expression levels of MagT1 mRNA and protein, the expression level of CD8+ T lymphocyte surface molecule NKG2D and the level of Mg²⁺ in PBMCs of the patients in mild-moderate CHB group were decreased(P<0.05),and the expression levels of miR-194-5p mRNA in PBMCs and CD8+ T lymphocyte surface molecule PD-1 of the patients were increased (P<0.05).The dual luciferase reporter gene assay results confirmed that MagT1 was a miR-194-5p target gene. Conclusion: MiR-194-5p may lead to chronic development of hepatitis B by down-regulating the expression of MagT1, causing MagT1-mediated Mg²⁺ influx disorder and resulting in the decrease of the immune activity of CD8+ T lymphocyte.

Key words: hepatitis B virus, peripheral blood mononuclear cell, miR-194-5p, magnesium transporter protein 1