调节性B细胞在肾移植术后抗体介导的排斥反应中的作用及艾拉莫德的干预研究

Antibody-mediated rejection (ABMR) remains to be one of key factors influencing the long-term survival of renal transplant recipients. However, the mechanism of ABMR is still unclear. Regulatory B cells (Breg) regulates the differentiation of B and T lymphocytes by secreting cytokines, such as interleukin-10, which plays an important role in the immune system. Our previous studies showed that, the proportions of Breg and regulatory T cells (Treg) in the recipients suffering from ABMR were significantly decreased, whereas the T helper 17 (Th17) remarkably increased; moreover, the contrary tendencies were observed in the recipients with the administration of Iguratimod. Accordingly, we put forward the hypothesis: Breg could promote the differentiation of Treg and reduce the differentiation of Th17 by targeting the Th17/Treg balance, leading to the attenuation of the production of donor-specific antibody (DSA). Iguratimod could increase the production of Breg, contributing to the regulation of Th17/Treg balance and decrease of DSA production, which could exert the beneficial function in the pathogenesis of post-transplant ABMR. To verify this hypothesis, this project will investigate the role and mechanism of Breg on the regulation of Th17/Treg balance and the production of DSA by the rat ABMR kidney transplantation model and rat ABMR cell culture model. Moreover, the influence and its related mechanism of Iguratimod on the functions of Breg and pathogenesis of post-transplant ABMR will be further explored. The expected results of this project will provide novel clues and targets for the prevention and treatment of post-transplant ABMR from the regulation of Breg, and promote the clinical administration of Iguratimod to induce the transplant immune tolerance.

抗体介导排斥反应（ABMR）是影响肾移植受者长期存活的重要因素，其机制不明。调节性B细胞（Breg）可通过分泌IL-10等因子调节B、T细胞的分化及功能，在免疫调节方面发挥重要作用。我们前期发现，发生ABMR的受者体内Breg和调节性T细胞（Treg）比例显著降低，辅助性T细胞17（Th17）的比例升高；服用艾拉莫德的ABMR受者趋势相反。据此提出假说：Breg可通过调节Th17/Treg平衡，导致Treg比例增加，Th17比例降低，从而减少供者特异性抗体（DSA）的产生；艾拉莫德可通过促进Breg的产生，调控Th17/Treg平衡，减少DSA的产生，进而减缓术后ABMR发展。为验证上述假说，本课题拟通过构建大鼠肾移植ABMR动物和细胞模型，探讨Breg在Th17/Treg平衡和ABMR发生中的作用及机制。本课题预期成果将为从Breg角度研究肾移植术后ABMR的防治措施提供新线索和靶标。

本项目旨在探讨艾拉莫德对肾移植术后抗体介导排斥反应（ABMR）发生的作用，并从动物、细胞等多层面深入探究艾拉莫德减缓ABMR的分子机制。为完成上述内容，本项目开展了艾拉莫德联合传统免疫抑制方案治疗ABMR的临床研究，并构建了同种异体小鼠肾移植ABMR模型、细胞模型等不同平台，探究艾拉莫德通过影响B细胞分化、Th17细胞分化等不同机制减缓ABMR的调控机制。本研究首次报道艾拉莫德联合传统免疫抑制方案可明显降低HLA高错配肾移植受者急性排斥反应的发生率，并显著降低受者体内的供者特异性抗体（DSA）滴度。艾拉莫德还可以在肾移植术前、术后有效降低受者体内DSA的水平，这一治疗方案具有较高的安全性，受者并未出现严重的副反应及并发症。在此基础上，我们探讨了艾拉莫德减缓ABMR的发生机制。在ABMR受者及小鼠模型中，我们均发现了B细胞向浆细胞过度分化是ABMR发生的重要机制，而艾拉莫德可靶向B细胞活化中的重要负性调控因子——PTPN22以抑制浆细胞分化，进而减少DSA的产生，实现减缓ABMR发生的生物学效应；此外，我们还在ABMR小鼠模型及二次皮肤移植模型中发现了Th17分化明显增加，而艾拉莫德可显著抑制Th17分化，这一机制也部分解释了艾拉莫德减缓ABMR发生的机制。本项目的研究成果不仅证实了艾拉莫德在减缓肾移植术后ABMR的发生、肾移植受者DSA水平降低等临床防治中的重要作用，而且从分子机制上探讨了艾拉莫德的作用途径，为后续研究奠定坚实的基础。