LC3相关吞噬pRBCs在DC调节红内期疟原虫特异性CD8+ T细胞反应中的作用和机制研究

Plasmodium specific T cells were necessary for the the host's immune protection against erythrocytic stage. However, the underlining mechanism of T cells activation remains largely unknown. Recent studies have comfirmed that DCs play an important role in the regulation of plasmodium specific T cell activation. Meanwhile, our preliminary data found that DC can phagocytose pRBCs and induce a noncanonical autophagy pathway resembling that of LAP (LC3-associated phagocytosis). DC LAP conditional deficiency can significantly restrain the plasmodium specific CD8+ T activation and promote the proliferation of plasmodium, but the mechanism remains unclear. Here, we firstly would like to further confirm whether DC LAP can regulate parasite specific CD8+ T cell activity, enhancing host immune protection. Then, flow cytometry, immunofluorescence will be carried out to explore the possible mechanism of DC LAP modulating parasite specific CD8+ T cell activation in erythrocytic stage infection. This study could not only shed new light on the activation mechanism of parasite specific CD8+ T cell, but also provide necessary theoretical basis for the design of effective blood-stage malaria vaccine.

疟原虫特异性CD4+/CD8+ T细胞在宿主抗红内期免疫保护中作用关键，而DC在活化疟原虫特异性CD4+/CD8+ T细胞中发挥着重要的调节作用。课题组前期在探讨DC吞噬pRBCs(感染疟原虫红细胞)调节疟原虫特异性CD4+/CD8+ T细胞活化的研究中发现，DC可以通过LC3 相关吞噬(LAP) pRBCs。同时采用DC细胞 ATG5条件缺失小鼠 (已证实LAP也消失) ，证实吞噬pRBCs形成的LAP可以通过增强疟原虫特异性CD8+ T细胞活性，抑制红内期疟原虫增殖，但具体分子机制并不清楚。鉴此，本项目拟一方面进一步证实DC细胞可以通过对pRBCs的LAP调节疟原虫特异性CD8+ T细胞活性，增强宿主免疫保护作用；另一方面对DC通过LAP调节疟原虫特异性CD8+ T细胞活化的分子机制进行深入探讨。这不仅有助于加深对红内期免疫保护机制的理解，同时可为疟疾免疫防治提供必要理论依据。

疟疾最终消除有赖于成功疫苗的研制，然而，目前尚无安全、高效疟疾疫苗问世。究其原因，主要在于我们对宿主抗疟原虫免疫保护机制的认识仍不清楚。本项目紧紧围绕宿主抗疟原虫免疫保护效应机制这一重要科学问题开展研究，主要包含以下几部分：1) 通过探讨DC LC3 相关吞噬(LAP)在调节红内期疟原虫特异性T细胞反应中的作用和机制研究，明确证实DC LAP缺失可以通过增强疟原虫特异性T细胞(CD4/CD8+ T细胞)活性，从而提高宿主抗红内期疟原虫免疫保护能力；2) 通过采用红内期感染治愈全虫疫苗模型，明确证实PD-1/PD-L信号缺失能通过炎症因子IL-10、IFN-γ以及MCP-1增强TFH细胞活性，进而促进疫苗诱导宿主体液免疫能力，提高疫苗诱导宿主免疫保护效果；3) 通过采用红内期全虫灭活疫苗模型，明确证实传统抗疟药-氯喹能通过增强红内期全虫疫苗诱导宿主体液免疫水平，增强宿主免疫保护能力，提示氯喹有望成为一种新型免疫佐剂。上述研究成果有助于加深对宿主抗疟原虫免疫保护机制的理解，同时可为红内期疟疾疫苗的成功研制提供必要理论依据。