MMP-9 Activity Mediates Vascular Effects of Inhaled Environmental Air Pollutants

动脉粥样硬化是一种与动脉斑块产生相关的炎症性疾病，是世界范围内发病率和死亡率的主要原因。斑块破裂通常导致临床结果，如中风或急性心肌梗死（AMI）。大量流行病学证据表明，颗粒和气态空气污染物与心血管事件发生率增加有关，但所涉及的细胞途径尚未阐明。动脉细胞外基质（ECM）的重塑是动脉粥样硬化进展的关键步骤，主要通过基质金属蛋白酶（MMP）活性进行调节。我们已经报道了血管MMP-9升高与暴露于汽车尾气有关，但是MMP-9在该模型中的调节尚未阐明。本提案的目的是验证暴露于无处不在的环境空气污染物，车辆发动机排放（VEE），导致氧化脂蛋白（oxLDL）介导的内皮素-1 （ET-1）的诱导和血管和循环MMP-9的激活，通过ET-1 - ETA丝裂原活化蛋白激酶（MAPK）信号通路。对于提出的实验，我们将使用易发生动脉粥样硬化的ApoE基因敲除小鼠。在Aim 1中，我们将分别通过使用ET-1受体拮抗剂（BQ-123）和MMP抑制剂，研究ET-1介导的血管MMP-9表达和MMP组织抑制剂（TIMPs）在VEE暴露后的分子通路。我们将分析MAPK通路ERK1/2、p38和JNK的表达。在Aim 2中，我们将确定VEE是否导致BQ-123治疗后冠状动脉和脑血管ET-1和MMP-9升高。

Atherosclerosis, an Inflamniatory disease associated with the production of arterial plaques, is the leading cause of morbidity and mortality worldwide. Plaque rupture commonly leads to clinical outcomes such as stroke or acute myocardial infarction (AMI). Substantial epidemiological evidence indicates that particulate and gaseous air pollutants are associated with increased rates of cardiovascular incidents, however the cellular pathways involved have not yet been elucidated. Remodeling of arterial extracellular matrix (ECM) is a crucial step in the progression of atherosclerosis, which is primarily regulated through matrix metalloproteinase (MMP) activity. We have reported elevated vascular MMP-9 associated with inhaiational exposure to vehicular exhaust, however regulation of MMP-9 in this model has not been elucidated. The goal of this proposal is to test the hypothesis that exposure to the ubiquitous environmental air pollutant, vehicular engiiie emissions (VEE), results in oxidized lipoprotein (oxLDL)-mediated induction of endothelin-1 (ET-1) and activation of vascular and circulating MMP-9 through an ET-1 - ETA mitogen activated protein kinase (MAPK) signaling pathway. For the experiments proposed, we will utilize atherosclerosis-prone ApoE knockout mice. In Aim 1, we will investigate Ihe molecular pathways involved in ET-1-mediated expression of vascular MMP-9, and regulation of MMP tissue inhibitors (TIMPs), following exposure to VEE, through use of an ET-1 receptor antagonist (BQ-123) and a MMP inihibitor, respectively. Resulting MAPK pathway ERK1/2, p38, and JNK expression will be analyzed. In Aim 2, we wili detennine whether VEE results in elevated ET-1 and MMP-9 in the coronary and cerebrovasculature with BQ-123 treatment. MMP-9 and TIMP expression, and cellular localization will be analyzed. In Aim 3, we. will elucidate the role of oxLDL signaling, via lectin-like oxLDL receptor (LOX-1), in regulating induction .of ET-1 and MMP9, in response to exposure to VEE by anti-LOX-1 antibody expression knockdown^ In Aim 4, we will deterrnine whether exposure to common environmental air pollutants (VEE,: mixed gasolinerand diesel exhaust) results in expression of circulating biomarkers, MMP-S and soluble LOX-1, in murine and-human samples. :