溶血磷脂酸促进巨噬细胞侵蚀斑块纤维帽及其机制研究

A thinning fibrous cap is the most important reason for the rupture of vulnerable plaque. Lysophosphatidic acid （LPA）is a kind of phospholipid signaling molecules, which presents in the ox-LDL, more than 20 times higher than the normal area in the plaque lipid core. Our experiment showed that serum MMP9 was significantly higher in patients with vulnerable plaques, and recently we found that serum LPA and miR-16 were also elevated in these patients. We also found that LPA promoted the expression of miR-16 and the secretion of MMP9 of human macrophages. These founding suggested that LPA played an important role in the matrix degradation of the fibrous cap. This project intends to focus on the MMPs secretion, the important biological behavior of macrophages involved in thinning of the fibrous cap and to study:①the effects of LPA on promoting MMP9 secretion by miR-16 and MMPs secretion by autophagy in human macrophages and its receptors regulation mechanism that may mediate the above actions of LPA;②validate the relevance of LPA,miR-16, MMP9 and so a group of molcules with vulnerable plaque. The project aims to reveal the role and mechanism of LPA in promoting macrophage to erode the fibrous cap and then to clarify LPA receptor is the new intervention target for stabilizing the fibrous cap and preventing plaque rupture.

薄的纤维帽是易损斑块破裂的最重要原因。溶血磷脂酸（LPA）是一种脂类信号分子，存在于ox-LDL中，以高于正常区20倍的量存在于斑块脂核内。我们实验表明易损斑块患者血清MMP9显著升高，近期发现这类患者血清LPA、miR-16水平也升高，还发现LPA促进培养的巨噬细胞miR-16表达和MMP9分泌，推测LPA在纤维帽基质降解中具有重要作用。本项目拟①以巨噬细胞侵蚀斑块纤维帽的重要环节：分泌MMPs为靶点，研究人巨噬细胞中LPA通过miR-16促进MMP9分泌和通过自噬促进MMPs分泌及其受体调节机制；②在人群中初步验证LPA、miR-16、MMP9等一组分子与易损斑块的相关性。本项目旨在揭示LPA促进巨噬细胞侵蚀斑块纤维帽的作用及其机制，阐明LPA受体是稳定纤维帽，防止斑块破裂的新的干预靶点。

薄的纤维帽是斑块不稳定性的重要原因。溶血磷脂酸（LPA）是一种脂类信号分子，以高于正常区20倍的量存在于斑块脂核中。我们的实验研究表明不稳定斑块患者血清MMP-9含量显著升高，因此我们以巨噬细胞分泌MMP-9降解斑块纤维帽为重要环节，研究LPA是否可通过调控巨噬细胞MMP-9的表达、分泌进而参与斑块的不稳定性。首先在细胞水平研究发现miR-16和miR-21可作用下游的RECK靶点调节巨噬细胞MMP-9的表达和分泌，进一步LPA刺激巨噬细胞发现LPA可上调miR-21表达，siRNA和抑制剂实验表明miR-21参与LPA调节巨噬细胞MMP-9的表达和分泌。同时研究发现ERK1/2以及下游的NF-κB也参与LPA介导的巨噬细胞MMP-9的表达。随后对参与LPA诱导巨噬细胞表达、分泌MMP-9的LPA受体研究发现，LPA2受体参与介导下游的信号通路，进而调控MMP-9的表达和分泌。临床冠状动脉斑块组织研究证实LPA生成酶ATX和MMP-9在不稳定斑块中表达显著升高，且存在共定位现象。在体动物实验中发现给予LPA2受体抑制剂可以显著的抑制高脂饮食诱导的斑块进展，而反向给予LPA2受体激动剂则促进斑块的发展。人群水平检测发现miR-21和MMP-9含量在非钙化斑块人群中显著高于钙化斑块组和正常组人群，提示二者与斑块的发展进展有关；同时检测AMI患者外周血LPA和MMP-9发现二者水平显著升高，且存在显著的相关性，提示LPA和MMP-9可能与不稳定斑块的形成及破裂有关。综上所述，本研究从细胞、动物以及人群水平阐明了LPA通过LPA2调控巨噬细胞表达、分泌MMP-9的机制，LPA与MMP-9的关系以及作为识别斑块不稳定性生物标志物的临床价值，为防止斑块的不稳定发展提供了新的干预靶标。