Effects of oxymatrine on the serum levels of T helper cell 1 and 2 cytokines and the expression of the S gene in hepatitis B virus S gene transgenic mice: A study on the anti‐hepatitis B virus mechanism of oxymatrine

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Abstract
Background: Oxymatrine has been shown to have a remarkable inhibitory activity to hepatitis B virus (HBV) infection with a hepatitis B virus e antigen (HBeAg) serum conversion rate of approximately 45%. In order to explore the anti‐HBV mechanism of oxymatrine, the effects of oxymatrine on serum levels of T helper (h)1 cytokines (interferon (IFN)‐γ and interleukin (IL)‐2) and Th2 cytokines (IL‐4 and IL‐10), and the expression of S gene in HBV S gene transgenic mice were studied. Methods: Each transgenic mouse was either injected with oxymatrine or saline intraperitoneally once a day for 30 days. Serum levels of IFN‐γ, IL‐2, IL‐4 and IL‐10 were quantitated and compared to the data before the treatment. The expression of HBV S gene in transgenic mice was analyzed at the DNA, mRNA and protein levels. Results: The serum levels of IFN‐γ in transgenic mice before or after oxymatrine treatment were 3.108 ± 3.172 and 11.059 ± 6.971 pg/mL, respectively. In contrast, serum levels before and after oxymatrine treatment for IL‐4 were 29.045 ± 13.235 and 13.024 ± 9.002 pg/mL, respectively (P < 0.001). The serum levels of IL‐2 in the control (saline injection) and oxymatrine‐treated mice were 1.070 ± 0.447 and 5.537 ± 2.887 pg/mL, respectively (P < 0.0001); and that of IL‐10 were 97.226 ± 73.306 and 33.607 ± 23.154 pg/mL, respectively (P < 0.01). No significant differences were observed in the expression of HBV S gene in the transgenic mice at the DNA, mRNA and protein levels before or after oxymatrine treatment. Conclusions: The fact that Th1 cytokines are increased while Th2 cytokines are decreased suggests that oxymatrine treatment triggers the change of immune response to hepatitis B infection in transgenic mice, which leads to improved HBV inhibitory activities. The study can help us better understand the mechanisms of the anti‐HBV drug, oxymatrine, and how it has potential as an application in clinical chronic hepatitis B treatment.© 2002 Blackwell Publishing Asia Pty Ltd