调节性B细胞在慢性HBV感染中的免疫负性调控作用及机制研究

The mechanisms of hepatitis B virus (HBV) persistence are not fully elucidated but the impairment of cellular immune responses is important. There is increasing evidence that B cells may involve in the immune control of chronic HBV infection. Recently published data indicate that regulatory B cells (Breg) may play a crucial role in the negative regulation of immunity. Our unpublished data demonstrated that B cells were increased in the peripheral blood of patients with chronic HBV infection and the main cause of this was the increased Breg cells. Furthermore, Breg cells were significantly increased in the immune reactive HBeAg-positive phase of chronic HBV infection as compared with the immune tolerant phase and healthy controls. On the basis of these findings and our experience in B cells study, we will explore the change characteristics of the percentage of Breg cells and the expression of Toll-like receptors (TLRs) on Breg cells in the peripheral blood of different immune status of chronic HBV infection and during anti-viral treatment and reveal their clinical significances. Damage-associated molecular pattern molecules (DAMPs) levels will also be detected. Base on the optimal in vitro B cell culture system and B/T-cell co-culture system, we will investigate the influences of DAMPs on Breg cell expansion and its functions as well as the expression of TLRs on Breg cells. We will also clarify the impact of Breg cells on effector B cells and T cells in chronic HBV infection. These studies will reveal the important roles and mechanisms of Breg cells in the negative regulation of immunity in chronic HBV infection.

HBV感染慢性化的主要原因是由于宿主的细胞免疫功能受损，但其确切机制不明。越来越多的证据显示B细胞参与HBV感染宿主的免疫调控，新近研究发现其中调节性B细胞（Breg细胞）可能起到重要的免疫负性调控作用。我们前期研究提示慢性HBV感染者外周血B细胞数量增加，且主要为Breg亚群增多所致，同时发现Breg细胞数量在慢性HBV感染者的免疫活化期显著高于免疫耐受期及健康人群。本课题组拟系统观察慢性HBV感染不同免疫状态和抗病毒治疗各个时期患者外周血相关DAMPs、Breg细胞及其表面TLRs表达的变化规律，并结合临床特征明确上述免疫学指标变化的临床意义；在既往积累的B细胞研究基础上，优化体外B细胞刺激培养活化体系，明确相关DAMPs对Breg细胞表面TLRs表达及对Breg细胞克隆扩增和功能的影响，阐明Breg细胞在慢性HBV感染中对效应B细胞的负性调控作用。

HBV感染慢性化的主要原因是由于宿主的细胞免疫功能受损，但其确切机制尚不完全明确。越来越多的证据显示B细胞参与HBV感染宿主的免疫调控，新近研究发现其中调节性B细胞（Breg细胞）可能起到重要的免疫负性调控作用。本研究显示慢性HBV感染者外周血B细胞数量增加，且主要为Breg亚群增多所致，同时发现Breg细胞数量在慢性HBV感染者的免疫活化期显著高于免疫耐受期及健康人群。血清IL-10水平的变化与Breg细胞的变化相一致，并都与ALT、AST水平呈正相关性。HBcAg刺激培养可诱导慢性HBV感染者Breg细胞的增加并且产生IL-10水平增加。为了解慢性HBV感染的免疫调控机制提供了新的思路。但在建立共培养体系中遇到了困难，研究中进行了多种尝试和探索，但仍未能完成本项目中Breg细胞对Be细胞作用的研究。