可溶性Δ42PD1增强DNA疫苗诱导免疫应答的分子机制研究

Our research group has recently identified a new immunoregulatory molecule Δ42PD1, but its function is not fully understood so far. The in-depth study of the immunoregulatory function of Δ42PD1 contributes to a comprehensive understanding of the molecular process of the immune response. Our preliminary data showed that soluble Δ42PD1 (sΔ42PD1) significantly enhanced antigen specific immune responses induced by DNA vaccine sΔ42PD1-P24 in mice; and also showed that TLR4 neutralizing antibody inhibited cytokine release of dendritic cells (DC) induced by recombinant sΔ42PD1-P24. These data suggest sΔ42PD1 possibly enhances DNA vaccine-induced immune responses by targeting DC. To further investigate the mechanism of enhanced immune response induced by sΔ42PD1 in DNA vaccination of sΔ42PD1-P24, the project intends to study 1) the interactions between sΔ42PD1 and TLR4; 2) the effects of sΔ42PD1 on DC-mediated antigen cross-presentation; 3) the effects of sΔ42PD1/TLR4 pathway blockade on immune response induced by the DNA vaccine. The data of the project will elucidate the molecular mechanism of enhanced immune response induced by sΔ42PD1 in DNA vaccination, and provide new ideas for the development of DNA vaccines.

我们课题组近期发现了Δ42PD1这一免疫调节分子，然而其功能目前尚不完全清楚。深入研究该分子的免疫调节功能有助于全面理解机体免疫应答的过程。我们早期的研究发现，可溶性Δ42PD1（sΔ42PD1）可显著增强小鼠对DNA疫苗sΔ42PD1-P24的特异性免疫应答；还发现TLR4中和抗体可抑制sΔ42PD1诱导树突状细胞（DC）释放细胞因子。这些结果提示sΔ42PD1可能通过靶向DC的机制增强DNA疫苗诱导的免疫应答。为深入研究sΔ42PD1增强DNA疫苗诱导的特异性免疫应答的机制，本项目拟开展以下工作：1）sΔ42PD1-P24与TLR4的相互作用研究，2）研究sΔ42PD1对DC交叉递呈抗原的影响，3）研究阻断sΔ42PD1/TLR4对DNA疫苗诱导免疫应答的影响。项目的完成将阐明sΔ42PD1增强DNA疫苗诱导的免疫应答的分子机制，为DNA疫苗的研发开辟新的思路

我们近期发现了程序性死亡受体1（programmed cell death 1, PD1）的一种选择性剪接体，该剪接体与全长PD1相比框内缺少了42个碱基对，因此被命名为Δ42PD1。目前尚不清楚Δ42PD1的生理功能。本研究构建了DNA疫苗P24和Δ42PD1-P24，免疫BALB/c小鼠后，通过ELISpot、ELISA等方法证实，Δ42PD1可显著增强HIV-P24特异性免疫应答。靶向TLR4中和抗体、信号通路抑制剂和RNA干扰可在体外抑制细胞表面或重组Δ42PD1蛋白诱导PBMC释放炎症性细胞因子。通过表面等离子共振和免疫共沉淀技术进一步发现Δ42PD1可与TLR4直接结合。本研究阐明了Δ42PD1通过与TLR4相互作用，靶向DC细胞，增强特异性免疫应答的分子机制，为进一步开发基于Δ42PD1的DNA疫苗奠定了理论基础。此外，本研究制备了Δ42PD1特异性单克隆抗体，并开发出特异性检测Δ42PD1 RNA的方法，为深入研究Δ42PD1的功能奠定了方法学基础。最后本研究发现Δ42PD1的表达受IFNg的调控，并阐明了相关信号通路，为研究Δ42PD1的功能及其在疾病发生、进展中的意义奠定了理论基础。