血小板微粒：脓毒症中脂多糖转运新载体及其促进血管内皮细胞非经典途径焦亡的作用机制研究

微循环障碍是脓毒症进展的重要环节。既往研究发现脓毒症中血小板活化后形成的血小板微粒、血管内皮细胞非经典途径焦亡与疾病进展密切相关，但两者之间关系不详。课题组前期发现脓毒症患者血液中血小板微粒数量及其内含的脂多糖浓度均显著升高；脓毒症小鼠模型中血小板微粒数量亦显著升高，荧光检测发现部分血小板微粒内脂多糖呈阳性，其数量与肺微血管内皮细胞中非经典途径焦亡关键蛋白Caspase-11、GSDMD表达呈正相关。因此，我们猜想脓毒症中血小板微粒是否可作为载体，将脂多糖转运入血管内皮细胞内并激活非经典途径焦亡？本研究将从临床资料、动物及细胞实验三个层面探索脓毒症中：1.血小板微粒作为疾病严重程度分级及预后指标的意义；2.内含脂多糖血小板微粒的分子特性、产生方式及机制；3.内含脂多糖血小板微粒趋向、进入血管内皮细胞并激活非经典途径焦亡的机制。本项目探索了脓毒症中血小板与血管内皮细胞之间一种新的作用机制。

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Although multifactorial mechanisms have been proposed, microcirculatory disturbance has been thought to play a crucial role in the sepsis. Platelets activation, endothelial dysfunction and the platelet-endothelial cell interactions are the key process during microcirculatory dysfunction. Recent studies revealed that platelet microparticles (PMPs) were significantly produced when the sepsis occurred, which was parallel with the severity of sepsis. However, the detailed mechanism has not been illustrated. Our data also showed that the counts of PMPs were significantly increased in the septic shock patients when compared with those in septic patients and volunteers. Meanwhile, we used Limulus test to detect the LPS in the PMPs and found the concentration of LPS was also elevated in the septic shock patients. Moreover, we established a septic mice model (wild C57BL/6 mice and platelet depletion C57BL/6 mice) which was induced by intraperitoneal injection of FITC-LPS and found that LPS was positive stained in PMPs by fluorescence detection. The counts of PMPs were also associated with activation of caspase-11 and GSDMD, which were classical markers of non-classical pyroptosis in the vascular endothelial cells. On basis of the previous publications and our data, we speculated that PMPs might be a new vector of LPS, which could transfer the extracellular LPS into endothelial cells to induce the non-classical pyroptosis during sepsis. We try to verify our hypothesis through human subjects, in vivo mice models and in vitro cell experiments. The main objectives of the study are presented as follows: 1. To verify the role of PMPs as a prognostic marker for sepsis; 2. To reveal the origin and characteristic of LPS-positive PMPs; 3. To demonstrate the mechanism of interactions between LPS positive PMPs and endothelial cell.s This project will confirm and clarify a new interaction between platelets and endothelial cells.