脂筏异常在ITP发病中的作用研究

The lipid rafts are the dynamically variable cell membrane microdomains containing special lipid.The abnormal changes in the area and the structure will affect their stability and then may cause abnormal signal transduction,finally leading to the occurrence of diseases. In our previous researches，we found that GM1 content in lymphocytes from ITP patients was elevated than that of normal controls. In addition, activation in vitro were able to induce the expression of GM1 in lymphocytes, which illustrated that the content of lipid raft was associated with immune activations.Considering the effect of lipid raft on immune activation and the abnormal expression of lipid raft in lymphocytes from ITP patients, we speculated that lipid raft over expression was involved in ITP though influencing activation of lymphocytes. Thus in this project, we will detect the protein composition and actin polarization to find the reasons for abnormal lipid raft content in ITP patients. Meanwhile, to elucidate the role of lipid raft in ITP pathology, we will also focus on the effect of lipid raft aggregation on activation signaling, differeniation and apoptosis of T and B cells. Further more,we will targeted block aggregation of lipid raft in ITP mouse models and then evaluate the immune activation of lymphocytes,which will provide a theoretical basis of new treatment strategy for the ITP patients.

脂筏是细胞膜上一种含有脂质的动态可变微区。脂筏面积和结构的异常变化会影响其稳定性，进而引起异常的信号转导，最终导致疾病的发生。我们前期研究结果显示原发免疫性血小板减少症（ITP）患者T淋巴细胞表面神经节苷脂GM1的含量明显高于正常对照组，且活化后明显升高，说明脂筏含量与淋巴细胞活化相关。提示ITP患者淋巴细胞表面存在脂筏的分布异常，这些异常的脂筏通过影响淋巴细胞的活化参与ITP的发生。本项目中，我们拟通过检测脂筏蛋白组成及actin极化情况来阐明ITP患者脂筏聚集异常的原因；同时探讨脂筏异常聚集对T、B淋巴细胞活化信号转导及分化、凋亡等生物学行为的影响，进而全面阐明脂筏异常聚集在ITP发病中的作用。另外，进行体内外实验靶向减弱脂筏的异常聚集，观察其对ITP患者淋巴细胞的免疫异常是否具有逆转作用，为将来临床针对脂筏的靶向治疗策略提供理论基础。

脂筏是细胞膜上一种含有脂质的动态可变微区。脂筏面积和结构的异常变化会影响其稳定性，进而引起异常的信号转导，最终导致疾病的发生。文献报道脂筏的异常参与多种自身免疫性疾病的发生，但其在ITP中的作用尚不清楚。本项目探讨脂筏在ITP发病中的作用。研究发现：（1）ITP患者T淋巴细胞表面神经节苷脂GM1的含量明显高于正常对照组，且活化后明显升高，说明脂筏含量与淋巴细胞活化相关。并提示ITP患者淋巴细胞表面存在脂筏的分布异常，这些异常的脂筏通过影响淋巴细胞的活化参与ITP的发生。（2）Methyl-β-cyclodextrin(MβCD)可以阻断ITP患者CD4+ 和 CD8+ T 淋巴细胞上脂筏自发聚集，进而通过抑制ITP患者T淋巴细胞的活化阻止其增殖及炎症因子的分泌。（3）由于ITP患者T淋巴细胞表面脂筏聚集异常造成淋巴细胞的过度活化，因而推测B细胞表面也可能存在活化信号的异常。进一步检测发现，ITP患者B细胞中PTEN表达下调，且与与血小板计数、血小板抗体产生及治疗反应相关。（4）对B细胞亚群的研究发现，ITP患者未成熟pre-naïve B细胞比例较正常对照升高，且其中PTEN及表面IL-21R的表达下降，而表面CD95的平均荧光强度高于正常对照。同时对PTEN调控机制研究发现IL-21或CD40L+anti-IgM都能促进正常B细胞中PTEN的表达，但无法诱导ITP患者B细胞中PTEN的表达。且PTEN的表达缺陷使得IL-21单独就能诱导ITP浆细胞的分化，进而增强自身反应性抗体的产生，加速疾病的进程。综上所述，本研究发现脂筏异常及淋巴细胞活化信号增强导致ITP患者淋巴细胞过度增殖、炎症因子分泌增加及B细胞过度活化及浆细胞增加，最终加速疾病进程。本研究的进行进一步拓宽了我们对ITP发病机制的认识，同时也为将来以脂筏为靶点的靶向治疗提供理论依据。该项目共发表文章22篇，其中SCI文章15篇。培养博士毕业生5名。