慢性HBV感染孕妇妊娠晚期抗病毒干预对母婴免疫系统影响的队列研究

Mother-to-infant transmission is the major mode of HBV transmission. It has been shown that antiviral intervention during the third trimester in pregnant women with high HBV load can effectively block HBV mother-to-infant transmission, given combination prophylaxis of HB vaccine and HB immunoglobulin for infants. However, several important issues related to antiviral intervention are still unresolved, such as mechanism underlying hepatic flare after antiviral discontinuation, and the influence of antiviral intervention on trained immunity of infants born to HBV+ mothers. In this project, we will establish study cohort of pregnant women with chronic HBV infection and follow up the mothers and their infants during pregnancy and after birth. According to recommendation in guideline, antiviral intervention will be suggested to pregnant women with high HBV load. Therefore, pregnant women in the cohort will be divided into two groups, intervention group and control group according to their willingness to accept antiviral intervention. The immunity of mothers and their infants will be analyzed by flow cytometry, multiple cytokine assay, and PCR array, etc. This project will focus on: (1) the impact of antiviral intervention during pregnancy on the immunity of mother and the relationship between antiviral intervention and hepatic flare pOstpartum; (2) Influence of antiviral intervention during pregnancy on the trained immunity and prophylactic efficacy of hepatitis B vaccination in infants; (3) corelation between trained immunity of newborns and mother-to-infant transmission. To study immunological issues related to antiviral intervention during pregnancy will not only be helpful to understand the immunological mechanism of preventing mother-to-infant transmission, but also provide scientific evidence for optimization of the public health strategy for preventing mother-to-infant transmission, therefore, will be benefical for further reduce the rate of mother-to-infant transmission.

母婴传播是乙肝病毒的主要传播途径。国内外指南推荐对高病毒载量的乙肝孕妇在妊娠晚期进行抗病毒干预以进一步减少母婴传播。然而，妊娠期抗病毒干预停药后肝炎活动的免疫学机制以及对新生儿训练后免疫的影响等重要问题，目前尚不明确。本项目以HBsAg+，HBeAg+孕妇为研究对象建立队列，在妊娠期及产后对孕妇及其婴儿进行随访。根据孕妇是否接受抗病毒干预分为干预组和对照组，使用流式细胞术、多重细胞因子检测、PCR阵列等技术分析母婴免疫学指标。主要研究内容包括（1）妊娠期抗病毒干预对母体免疫系统的影响及其与分娩后肝炎活动的关系;（2）妊娠期抗病毒干预对新生儿训练免疫及乙肝免疫接种效果的影响;（3）分析新生儿训练后免疫与母婴传播的相关性。本项目的开展，不仅有助于深入理解妊娠期抗病毒干预阻断母婴传播的免疫学机制，而且可以为优化阻断母婴传播的公共卫生策略提供科学依据，从而有利于进一步降低母婴传播的发生率。

为了进一步减少HBV母婴传播，越来越多的高HBV DNA载量的乙肝孕妇接受妊娠期抗病毒干预。妊娠期抗病毒干预停药后肝炎活动的免疫学机制以及是否会对新生儿免疫产生影响，目前尚不明确。我们首先建立了一个以慢性HBV感染孕妇为研究对象，开展了流行病学和实验室两个方面的研究。流行病学研究主要围绕乙肝母婴传播和慢性HBV感染孕妇产后肝炎活动展开；实验室研究采用免疫学技术，分析了妊娠期抗病毒干预对妊娠期和分娩后母婴免疫反应的影响。主要研究结果如下：（1）前瞻性研究：在完成随访的905例研究对象中，HBeAg阳性乙肝孕妇有561例（占61.9%），共有446例乙型肝炎孕妇接受了抗病毒治疗，占49.3%（446/905）。共有8例婴儿感染HBV，总体HBV母婴传播率为0.9%（8/905）。HBeAg+和高病毒载量是HBV母婴传播的危险因素（p=0.029, P=0.01）。（2）回顾性研究分析了慢性HBV感染母亲分娩后肝炎活动的影响因素，发现妊娠期ALT升高和服用替比夫定抗病毒治疗与分娩后肝炎活动有关；（3）比较分娩时抗病毒干预和非干预的母亲T细胞表型和功能，发现干预组Treg细胞频数明显高于非干预组（p=0.002）；在抗-CD3和抗-CD28的刺激下，干预组CD4+T细胞和CD8+T细胞分泌IFN-γ的能力明显低于对照组（p=0.005，p=0.028），干预组母亲CD4+T细胞和CD8+T细胞分泌IL10和IL4的能力高于非干预组母亲（p＜0.05）；（4）妊娠期抗病毒干预组中，产后15-18个月时出现HBeAg血清学转换和未转换的母亲相比，Treg频数的动态变化模式不同，转换组母亲在抗病毒期间Treg频数升高，产后Treg频数降低，而未转换组母亲在抗病毒期间Treg频数降低，产后Treg频数升高；（5）产后未出现肝功能异常的母亲和产后出现肝功能异常的母亲相比，产后出现肝功能异常的母亲在抗病毒干预前，抗病毒干预时，及产后CD4+T细胞和CD8+T细胞分泌Th1类细胞因子能力较强，而分泌Th2类细胞因子能力较弱。（6）妊娠期抗病毒母亲和妊娠期未抗病毒母亲所生新生儿的脐带血中T细胞表型和功能无明显差异，宫内暴露于母体来源的HBeAg对新生儿脐带血中的T细胞表型没有影响，但是可增强新生儿Th1类细胞因子的产生。