钙敏感受体参与肺血管内皮损伤的分子机制

Endothelial injury of pulmonary vessel is common in the pathogenesis of a variety of pulmonary vascular diseases, including chronic pulmonary hypertension. Inflammation and oxidative stress are two main factors that cause endothelial injury, but the mechanisms have not been fully elucidated. Recent studies suggest that CaSR may be an important molecule involved in vascular injury caused by cell inflammation, together with the applicant recent study showing that oxidative stress can increase CaSR sensitivity. The project intends to explore the molecular mechanisms of increased CaSR sensitivity induced by inflammation and oxidative stress in endothelial injury in depth. New advances in this field show that inflammatory mediators induce calcium oscillations to adjust downstream transcriptional activation and gene expression of inflammatory cytokines through its cumulative time of activation threshold. Preliminary experiments of the project show that cumulative time of inflammatory cytokines-triggered calcium oscillations was regulated by CaSR activation. Thus, applicants speculate that inflammation and oxidative stress can activate CaSR, induce calcium oscillations, regulate downstream transcription factors and NLRP3 inflammasome activation by cumulative time reaching threshold, and therefore play an important role in pulmonary vascular endothelium injury. The successful implementation of this project is expected to provide new clues for prevention and treatment of pulmonary vascular injury.

内皮损伤是多种肺血管疾病，包括慢性肺动脉高压的共同发病环节。炎症和氧化应激是造成内皮损伤的常见因素，但它们引起细胞损伤的机制尚未阐明。新近研究提示钙敏感受体(CaSR)可能是参与细胞炎症反应的重要分子。结合申请人最新研究发现，氧化应激增强CaSR敏感性。本项目拟深入探讨炎症介质和氧化应激通过CaSR参与肺血管内皮损伤的分子机制及其病理生理意义。新近研究进展表明炎症介质诱导的钙振荡通过其达到激活阈值的累积时间调节下游转录激活和炎症因子基因表达。申请人围绕本项目开展的预实验发现，炎症介质触发的钙振荡达到激活阈值的累积时间受CaSR调控。为此，申请人推测炎症和氧化应激激活CaSR，诱导钙振荡，通过其达到激活阈值的累积时间调控下游转录因子及NLRP3 炎性复合体激活，在肺血管内皮损伤中发挥重要作用。该项目的实施有望对肺血管内皮损伤的防治提供新的线索。

血管内皮损伤是包括肺高压在内的多种疾病发生的基础，已有研究表明炎症因子或氧化应激通过受体或非受体刺激血管内皮细胞产生钙振荡能够引起细胞损伤，但机制不明。钙敏感受体是一类G蛋白偶联受体，其激动剂能够诱导不同形式钙振荡的产生，但是钙敏感受体是否在炎症因子或氧化应激引起的钙振荡中发挥作用还不是很清楚。本项目研究发现，钙敏感受体参与调控组胺或过氧化氢引起内皮细胞产生钙振荡的持续时间，进而影响游转录因子NFkB转录活性及炎症因子IL-8的表达情况。为揭示钙敏感受体的作用机制，进一步研究发现组胺或过氧化氢通过细胞内产生过氧化氢调节钙敏感受体的聚合，钙敏感受体二聚体状态能够增强对配体的敏感性。同时钙敏感受体激活导致细胞内IP3水平增加，进而调节细胞内钙离子释放维持钙振荡的发生。以上研究结果表明，炎症因子或氧化应激诱导内皮细胞钙振荡产生的同时引起钙敏感受体的聚合，钙敏感受体的聚合通过增加IP3的产生进而延长组胺或过氧化氢诱导钙振荡的持续时间，促进转录因子NF-kB的转录激活，炎症因子IL-8的表达增加，最终导致内皮细胞损伤的发生，为抑制和缓解血管内皮损伤提供新的线索。