MBL诱导M-MDSC发育及其在类风湿关节炎的意义

We recently found that mannan-binding lectin (MBL) inhibited the differentiation of monocytes (Mos) into dendritic cells (DCs) in a DC-inducing culture system, but induced Mos to differentiate into myeloid derived suppressor cells (M-MDSCs) characterized by CD11b+ CD14+ CD33+ HLA-DRlow, high expresions of interleukin-10 and -6 and capable of inhibiting proliferation of, and IFN-γ production by autologous T cells. On the basis of these findings, we propose the present grant. The effects of MBL on M-MDSC development processes, including their phenotype, functional capacity and the mechanisms underlining these effects such as the relative signal pathways of M-MDSC development, will be studied. The level of MBL and the frequency and competence of M-MDSCs in blood or lymphoid tissues will be examined, and the association among MBL level, M-MDSCs’ frequency and competence, disease severity and tissue inflammation will be analyzed in patients with rheumatoid arthritis (RA) or in collagen-induced arthritis (CIA) mice. The features of MDSCs and the disease pathology in CIA mice will be also examined by MBL reconstitution or adoptive transfer of MDSCs. The innovation points and the significance of this project lie in: first, the viewpoint that MBL has a hand in acquired immune responses through regulating the development of M-MDSCS will be put forward, which will enrich the basic theory that innate immune system instructs acquired immune responses, and provide new theoretical bases and targets for treatment of diseases resulted from MBL imbalance and M-MDSC function disorder. Second, the pathogenesis mechanisms of MBL unbalance (deficiency or hyperfunction) will be expounded from a new viewpoint of immunoregulation disorder, which may supply new bases and strategies for treatment of this kind of diseases. Third, the relationship among MBL unbalance, M-MDSC disorder and RA disease severity will be revealed, which may help to elucidate the pathogenesis of RA and to develop novel strategies for RA therapies.

我们发现，在树突状细胞（DC）分化培养系统中，甘露聚糖结合凝集素（MBL）可抑制单核细胞（Mo）向DC分化而诱生CD11b+ CD14+ CD33+ HLA-DRlow、抑制T细胞功能的Mo型髓源抑制细胞（M-MDSC）。据此提出本项目，拟对MBL诱导M-MDSC发育及在类风湿关节炎（RA）的意义进行以下研究：①体外：细胞表型、功能及机制；②临床：MBL与M-MDSC及RA病情的关系；③动物模型：胶原诱导关节炎小鼠MBL与M-MDSC及病变的关系、补充MBL/过继M-MDSC的影响。创新点和意义有：①提出MBL通过调控M-MDSC发育参与免疫调节的新观点，将丰富天然免疫指导获得性免疫的基础理论。②从免疫调节紊乱新角度阐述MBL失衡有关疾病发病机制，为其治疗研究提供新的科学依据。③揭示MBL失衡—M-MDSC紊乱—RA病变的关系，为靶向MBL调控M-MDSC发育以治疗RA提供理论和实验依据。

甘露聚糖结合凝集素（MBL）是天然免疫系统中的关键分子，在抗感染免疫中起重要作用。髓源抑制细胞（MDSC）是来源于未成熟髓系细胞的具有免疫抑制功能的细胞群。本项目阐明了MBL对MDSC分化和功能的调节及其分子机制，并揭示了MBL对类风湿性关节炎的影响及调控机制。现已获得如下结果：①MBL缺陷小鼠来源骨髓细胞向M-MDSC的分化较WT小鼠骨髓细胞减弱，并且MBL缺失的MDSC细胞抑制T细胞活化功能强；②在肝脏免疫内环境中，MBL可通过影响肝星状细胞上COX2-PGE2轴，抑制MDSC的浸润；③类风湿性关节炎患者血清MBL水平与疾病严重程度相关指标呈负相关，机制研究表明MBL通过抑制p38-c-fos-NFATc1信号通路影响破骨细胞分化进而减轻关节炎的病变进程。此外，在本项目的资助下，我们研究了MBL对中性粒细胞迁移及T细胞增殖分化的调控作用，并揭示了MBL通过抑制肝细胞中CYP2E1的表达减轻对乙酰氨基酚（APAP）代谢所致肝损伤的作用机制；我们还研究了另一重要的模式识别受体DC-SIGN，建立了针对DC-SIGN的双抗体夹心ELISA检测体系，探究了可溶型DC-SIGN对LPS诱发炎症反应的调节作用。总之，本项目的主要意义在于：①揭示了MBL对MDSC发育分化及功能的调控，为MDSC的基础研究注入了新的内容，为人工干预MDSC分化及功能以防治有关疾病提供了新的理论依据；②从破骨细胞分化及功能这一新的角度，阐释了MBL缺陷与关节炎发生发展之间的关系，为靶向MBL治疗关节炎提供了理论和实验依据；③ 揭示了MBL对多种免疫细胞（如中性粒细胞和T细胞）和非免疫细胞（肝细胞）的免疫调控作用及相应的分子机制，为深入研究MBL的免疫调节功能增添了新的内容，有助于阐述MBL失衡（缺陷或过强）有关疾病的免疫病理机制。项目基本完成既定研究目标，发表相关科研论文7篇，其中SCI论文6篇。