纳米金载血管活性肠肽VIP抑制移植物抗宿主病效果及作用机制研究

The prevention and the treatment of graft-versus-host disease (GVHD) is still a big barrier that allo-HSCT needs to break. Our previous work found that the vasoactive intestinal peptide (VIP) was capable of inducing tolerant DCs (tDCs) in vitro, which could significantly inhibit the proliferation of T cells, suggesting that VIP has a potential for the treatment of GVHD; however, its in vivo therapeutic effect is still yet to be confirmed. The main objective of this study is to evaluate the the therapeutic effect of in vivo injected-VIP on GVHD treatment based on the mice model with visualized donor T cells. In addition, in order to improve the stability and the penetration of VIP, the feasibility of utilizing gold nanoparticles (AuNPs) as carriers to extend the metabolic cycle and lymphoid tissue targeting efficiency of VIP will also be explored. Furthermore, we are also to uncover the underlying mechanisms from the pathways of “the CD40/80/86 second signal”, “the Tregs-CTLA4” and “MIP-2/CXCR2” which are all tightly related to the activation, proliferation and chemotaxis of donor T cells. The in-depth investigation of the above issues will greatly improve our understanding of VIP, thus to expand the scope of its application, and finally to provide new strategies for the prevention and control of GVHD.

如何有效预防和治疗移植物抗宿主病（GVHD）仍是HSCT亟待解决的问题。我们前期研究发现，血管活性肠肽（VIP）可在体外诱导耐受性DCs（tDCs）的生成，且该tDCs可显著抑制T细胞增殖活化，提示VIP具备良好的预防和治疗GVHD的潜力，但其体内作用效果及机制还有待证实。为此，本课题提出以AuNPs共价偶联VIP，增强VIP体内稳定性，延长其代谢周期，同时促进VIP在淋巴细胞富集区聚集而实现淋巴组织靶向递呈，最终放大VIP免疫调节功能。本研究拟建立供者T细胞可视化GVHD小鼠模型，并利用多模态分子影像技术实时动态评价AuNPs/VIP抑制GVHD的效果；在此基础上深入探讨AuNPs/VIP是否分别通过“CD40/80/86第二信号途径”、“Tregs-CTLA4途径”以及“MIP-2/CXCR2途径”阻断供者T细胞激活、扩增及趋化作用，以揭示AuNPs/VIP抑制GVHD的分子机制。

在本项目的资助下，已成功制备出不同形貌和尺度的AuNP纳米载体的制备，并将其与血管活性肠肽VIP通过Au-S键成功偶联；该复合物可稳定存在，且可经血富集于脾脏中，为抑制受着T细胞过度激活奠定基础；同时，我们构建了T细胞可视化GVHD模型，并最终证明所构建的AuNP@VIP复合物可大大降低供者T细胞在急性GVHD受者小鼠内的过度增殖；进一步研究发现，AuNPs@VIP可显著抑制DCs分泌炎性因子水平及激活T细胞能力，应是其抑制GVHD发生的主要原因；最后，我们亦发现VIP 同家族神经肽UCN具有更强的诱导DCs耐受能力，基于此，我们进一步构建了GO@UCN复合物，发现其亦可极大缓解小鼠急性GVHD发生。