间质干细胞对CD23+CD43+调节性B细胞的调控作用及机制研究

We reported that mesenchymal stem cells (MSC) treatment for chronic graft-versus-host disease (cGVHD) is safe and effective. The numbers and function of CD5+ regulatory B cells were significantly increased after MSC treatment, suggesting that CD5+ Breg cells maybe as an important target for improving cGVHD by MSC. Since the heterogeneity of CD5+ Breg cells, the specific Breg cell subset that involved in improving cGVHD was still unknown. Further study showed that CD23+CD43+B cells, one subpopulation of IL-10 producing B cells, were significantly increased after co-culture with MSC, indicating that CD23+CD43+B cells may serve as a new subset of regulatory B cells. Therefore, this study will validate the regulatory effects of CD23+CD43+B cells both in vitro and in vivo. Next, the role of PGE2, IDO and other classic regulatory factor by MSC will be investigate in regulating the number and function of CD23+CD43+B cells. Moreover, the regulatory effects and mechanisms of TIMP-1, SPARC and other new molecules, which were discovered by RNA-sequence of MSC, will be illustrated in regulating CD23+CD43+ B cells. These studies will not only help to discover the new target for MSC treatment, but also laid the basis for supporting that regulatory B cells play a cure role in treatment of cGVHD.

申请人研究发现间质干细胞（MSC）治疗慢性移植物抗宿主病（cGVHD）安全有效，伴随临床症状改善CD5+调节性B细胞数量与功能显著增加，提示CD5+Breg可能是MSC治疗cGVHD的重要靶点，但CD5+B细胞是一群异质性细胞，具体是哪种亚群参与疗效改善亟待阐明。利用MSC/CD5+B细胞共培养体系筛选发现在表达IL10的调节亚群中，CD23+CD43+B细胞显著增加，提示该亚群细胞可能是新的调节B亚群；据此，本研究拟利用体内外模型系统证明CD23+CD43+B的免疫调节功能，探讨PGE2、IDO等经典调控在MSC改变CD23+CD43+B细胞数量与功能中的作用模式；进一步利用RNA-seq等技术发掘、验证TIMP-1、SPARC等新调节分子在MSC调控CD23+CD43+B细胞的作用机制；上述研究不仅有助于深入阐明MSC治疗的新靶标，也为发现调节性B细胞在cGVHD中的治疗作用奠定基础。

本项目旨在研究CD23+CD43+B细胞的免疫调节功能以及阐明间充质干细胞（MSC）对CD23+CD43+调节性B细胞的调控作用及其机制。利用体外B/T细胞共培养模型，证实CD23+CD43+B细胞是一个新的B细胞调节亚群，且其免疫调节功能主要依赖于IL-10分泌；阐明MSC能增加CD23+CD43+调节性B 细胞数量，并揭示MSC通过细胞-细胞接触和COX2/PGE2通路调控CD23-CD43-B细胞的转为CD23+CD43+B细胞，从而提高CD23+CD43+B细胞的数量。同时利用炎性疾病动物模型，进一步证实MSC对CD23+CD43+B细胞数量功能的调控作用以及CD23+CD43+B细胞在MSC治疗炎症相关疾病中的关键作用。在此基础上，利用RNA-seq技术，发现并验证了MSC免疫调节的新机制，包括证实MSC通过STC2抑制T细胞功能，并改善T细胞介导的疾病；发现TIMP-1、THBS-1、ICAM-1等参与MSCs调控调节性B细胞，为进一步阐明MSC免疫调节机制提供了坚实的基础。