The Dynamic Changes Of Serologic HBV Markers In Infants Born To HBsAg Carrier Mothers And The Distribution Of Toll-like Receptors In Placenta

【BACKGROUD】Hepatitis B is one of major worldwide spreaded infectious disease, which has a serious impact on people's life and health. In the Asia, hepatitis B virus (HBV) infection often was occured during the childhood. The transplacental intrauterine infection of HBV is one of important transmission modes. We have systematically explored the mechanism on HBV intrauterine transmission from 1992, and confirmed that HBV can be transmitted from mother to her fetus through the placenta. But there is no confirmed conclusion about which serologic HBV markers in the mother can be transmitted to the fetus and what dynamics of those markers are in their infants. Also, as we know, not all infants will become HBV infection, even whose placenta cells are infected by HBV. So it is very important to know the dynamics of seral HBV markers in infants and innate immune effect of the placenta, which would provide a significant evidence for understanding mechanism of HBV intrauterine infection and taking some effectual preventive measures for HBV infection control.【AIMS】1. To investigate the dynamic changes of hepatitis B virus serologic markers in HBsAg carrier mothers and their infants who accepted hepatitis B immunoglobulin combining hepatitis B vaccine immunization by follow-up study. And to evaluate the long-time blocking effectiveness and its clinical and epidemiological significances.2. To study on the distribution of toll-like receptor 3 (TLR3) and toll-like receptor 9 (TLR9) in human placenta and their role in the HBV intrauterine infection.【METHODS】1. Two hundred and nine HBsAg-carrying pregnant women and their 213 newborns (4 twins) were consecutively recruited from December 2002 to October 2004, who were followed up when infants were at 1, 7, 12, 24 and 36 month of age.2. Neonatal HBsAg was tested by Chemiluminescence. HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc in maternal and infantile sera were detected by ELISA. HBV DNA was detected by PCR method.3. Twenty two full-term placental tissues of HBsAg carriers and 6 ones of HBsAg sero-negative pregnant women were collected. The HBsAg, TLR3 and TLR9 in the placental tissues were investigated by StreptAnidin-Biotin peroxidase Complex (SABC) immunohistochemical staining.【RESULTS】 1 In follow-up study:1.1 One hundred and eighty two infants (85.45%) born to HBsAg positive mothers were followed up. 13 infants were HBsAg positive at birth, and only 2 of those infants born to HBsAg, HBeAg and HBV DNA all positive mothers were persistently positive for HBsAg. The other infants all became HBsAg-negative and no infant changed to HBsAg-positive.1.2 The anti-HBs positive rate of newborn infants was 6.70%(12/179) with intervention of hepatitis B immunoglobulin (HBIG) injecting in mothers during the pregnancy. After infants were immunized by HBIG combining with hepatitis B vaccine, the anti-HBs positive rate reached to 82.46% (47/57) at 1 month of age and 91.77%(145/158) at 7 month of age. Descended gradually thereafter, 70.83%(102/144) infants at aged 24 month and 73.68%(28/38) infants at aged 36 month showed detectable levels of anti-HBs. There was a negative correlation between anti-HBs production in infants and HBsAg-positive at birth (RR=4.96,95% CI:1.77～13.91). While both HBsAg and HBeAg positives in their mothers or HBeAg positive in infants at birth did not relate to the produce of anti-HBs in infants(P>0.05).1.3 About 57.69%(30/52) neonates born to HBsAg and HBeAg positive mothers showed detectable levels of HBeAg. After 7 months of age, HBeAg was still detectable in 2 infants, and both of them were also HBsAg positive. The other infants all became HBeAg-negative. None of the other 157 HBeAg-negative infants at birth became HBeAg-positive during follow-up.1.4 The anti-HBe positive rate of infants at 1 month of age was 49.12% (28/57), and the anti-HBc positive rate was 100%. The anti-HBe positive rate of infants at 7 month of age decreased to 7.59% (12/158), while anti-HBe was still detectable in 1 infant at aged 12 month, and all infants become anti-HBe- negative at aged 24 month. But the anti-HBc positive rate was still 84.81% (134/158) at 7 month of age. 33.33% (10/30) infants at aged 12 month and 34.03% (49/144) at aged 24 month showed detectable levels of anti-HBc, decreased to 21.05% (8/38) at aged 36 month.2 The detections of HBsAg, TLR3 and TLR9 in the placenta:2.1 The HBsAg positive rate in the full-time placental tissues from HBsAg carrier pregnant women was 77.27% (17/22). The positive signals of HBsAg could locate in the cytoplasms of decidual cells, trophoblastic cells, villous meseachymal cells and villous capillary endothelial cells.2.2 The positive signals of TLR3 major locate in the cytoplasm of trophoblastic cells and villous meseachymal cells in the HBsAg-positive placental tissues. TLR3 could not be found in the placenta of HBsAg sero-negative pregnant women. While the positive signals of TLR9 could locate in the cytoplasm of trophoblastic cells, villous meseachymal cells and villous capillary endothelial cells in the HBsAg-positive placental. The trophoblastic cells in the placentas of HBsAg sero-negative pregnant women also expressed TLR9. But the positive signals of TLR9 in the HBsAg positive placental were stronger than in the HBsAg-negative placentas. In a HBsAg-positive placenta, the expression and distribution of TLR9 were stronger and more expanding than TLR3.【CONCLUSIONS】1 The transplacental intrauterine infection rate of HBV was about 6.10% (13/213), and its chronic progressive rate was about 15.38% (2/13).2 The efficacy of HBIG combining hepatitis B vaccine in high risk infants born to HBsAg carrier mothers was fine. And the anti-HBs positive transferred rate was similar to the immunizing level of average people.3 HBeAg, anti-HBe and anti-HBc could pass through human placental from mother to fetus passively. So they can't be used as diagnostic indexes for HBV intrauterine infection.4 Preliminary considering, HBV stimulation may possibly activate and strongly enhance TLR9 protein expression in placenta. Whereas there may be only weak response of TLR3 to HBV stimulation.