Effects of hepatitis B virus on the expression of Toll-like receptor 9,interferon regulatory factor-7,and interferon-α in plasmacytoid dendritic cells in the umbilical cord blood of healthy parturients

Objective To investigate the effects of hepatitis B virus( HBV) on the expression of Toll- like receptor 9( TLR9),interferon regulatory factor- 7( IRF- 7),and interferonα( IFNα) in plasmacytoid dendritic cells( pDCs) cultured in vitro in the umbilical cord blood of healthy parturients. Methods Hep G 2. 2. 15 cells were cultured in vitro,and the culture supernatants of Hep G 2. 2. 15 in each well were collected. HBV particles were obtained by ultracentrifugation,and HBV DNA concentration was measured by fluorescent- probe PCR. pDCs( on day 7 of culture) and HBV( 1 × 105 copies / ml,1 × 106 copies / ml,1 × 107 copies / ml,and blank control) were co- cultured for 24 hours,and then cultured continuously for another 24 hours with Cp G ODN 2216 at a final concentration of 2 μg / ml. The mRNA expression of TLR9 and IRF- 7 in pDCs was measured by real- time PCR,the protein expression of TLR9 and IRF- 7 in pDCs was measured by Western blot,and the level of IFNα was measured by ELISA. The analysis of variance was used for comparison of continuous data between multiple groups,and the SNK- q test was used for comparison between any two groups; the common logarithms of HBV DNA copies were obtained,and the linear regression analysis was performed to investigate the correlation between related indicators and the common logarithms of HBV DNA copies. Results Compared with the blank control group and the HBV 1 × 105 copies / ml group,the HBV 1 × 106 copies / ml and HBV 1 × 107 copies / ml groups had significantly lower mRNA expression of TLR9 and IRF- 7,significantly lower protein expression of TLR9 and IRF- 7,and significantly lower expression of IFNα( all P < 0. 05). The inhibitory effects of HBV on the mRNA expression of TLR9 and IRF- 7,the protein expression of TLR9 and IRF- 7,and the expression of IFNα in the culture supernatants of pDCs rose with the increasing HBV DNA load( r =- 0. 729,- 0. 761,- 0. 657,- 0. 703,and- 0. 803,all P < 0. 05). Conclusion After in vitro treatment with HBV,the mRNA and protein expression of TLR9 and IRF- 7 in normal pDCs is reduced,leading to reduced secretion of downstream IFNα. HBV can inhibit the function of normal pDCs and cause persistent HBV infection.