PIK3CD获功能突变对CD8+T细胞记忆的影响及其代谢调控机制

APDS1是由PIK3CD基因获功能突变(PIK3CD GOF)引起编码蛋白P110δ(PI3Kδ)持续活化的原发性免疫缺陷病,然而，其致病机制尚不完全清楚。前期结果表明PIK3CD GOF通过诱导T细胞糖代谢方式改变，驱使TNaive细胞过度活化。在此基础上，我们利用细菌和病毒感染模型，发现PIK3CD GOF小鼠抗原特异性CD8+TMem受损，但其调控机制尚不明确。因此，本项目以前期PIK3CD GOF小鼠为基础，利用条件PIK3CD GOF表达小鼠，借助OT-I、CD45.1和CD45.2等模式动物，结合APDS1患者样本，明确PIK3CD GOF对CD8+TMem的影响，解析PIK3CD GOF致CD8+TMem受损的具体环节并阐释其代谢机制，探索和挖掘PIK3CD GOF致CD8+ TMem受损的其他可能调节机制，为APDS1及相关免疫紊乱性疾病的治疗提供新的实验基础和理论依据。

Activated phosphoinositide 3-kinase δ syndrome type 1 (APDS1) is an autosomal-dominant primary immunodeficiency disorder resulting from pathogenic gain-of-function (GOF) mutations in the PIK3CD gene. However, the mechanisms by which PIK3CD GOF contributes to this abnormal immune homeostasis in patients remain unknown. Our previous studies from patients with APDS1 and genetic mouse models indicated that an enhanced capacity for aerobic glycolysis is required for PIK3CD GOF-induced TNaive cell overactivation and hyperproliferation. Based on this, we recently found that the frequency and absolute numbers of antigen-specific CD8+ T cells, and the ability of antigen-specific CD8+ T cells to produce cytokines were obviously decreased at memory phase in PIK3CD GOF mice following LCMV Armstrong or rLm-OVA injection. In addition, PIK3CD GOF reduced the recall response of memory CD8+ T upon antigen rechallenge. However, the molecular regulatory mechanisms of impaired memory CD8+ T caused by PIK3CD GOF were poorly understood. Therefore, in this project, we will completely analysis the effects of PIK3CD GOF on the dynamic changes of memory CD8+ T cell by utilizing the PBMCs samples from APDS1 patients, the conditional and inducible phase-specific PIK3CD GOF mice models, and the systemic PIK3CD GOF mouse model previously constructed with CRISPR/Cas9 and other animal models including OT-I, CD45.1 and CD45.2. In addition, we will determine the regulatory process of PIK3CD GOF on the formation, contraction, and maintenance of memory CD8+ T, and further dissect the associated metabolic mechanisms by analyzing the glucose-lipid metabolism. Furthermore, we will do our best to explore the other pathogenic mechanisms of blunted memory CD8+ T with transcritomics strategy. This proposed study has the potential to shed new light on clinically progressive mechanisms of APDS1 and to lay the foundation for treatment of APDS1 and similar immune disorders.