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

描述(由申请人提供) 动脉粥样硬化是一种与动脉斑块形成相关的炎症性疾病，是全球发病率和死亡率的主要原因。斑块破裂通常会导致中风或急性心肌梗死(AMI)等临床结果。大量的流行病学证据表明，颗粒物和气态空气污染物与心血管发病率的增加有关；然而，所涉及的细胞途径尚不清楚。动脉细胞外基质(ECM)重塑是动脉粥样硬化进展过程中的关键步骤，其主要受基质金属蛋白酶(MMPs)活性的调节。研究人员已经报道，吸入汽油废气与血管中的基质金属蛋白酶-9升高有关；然而，在这个模型中，基质金属蛋白酶-9的调节还没有阐明。这项建议的目的是验证一种假说，即暴露于普遍存在的环境空气污染物--汽油发动机排放(GEE)，会导致氧化脂蛋白(OxLDL)介导的内皮素-1(ET-1)诱导，并通过ET-1-ETA丝裂原激活蛋白激酶(MAPK)信号通路激活血管和循环中的基质金属蛋白酶-9。对于提议的实验，研究人员将利用易患动脉粥样硬化的载脂蛋白E基因敲除小鼠。在目标1中，他们将分别通过使用ET-1受体拮抗剂(BQ-123)和基质金属蛋白酶抑制物(MMPI)，研究在GEE暴露后，ET-1介导的血管基质金属蛋白酶-9的表达以及对基质金属蛋白酶组织抑制物(TIMPs)的调节的分子途径。由此产生的MAPK通路ERK1/2、p38和JNK的表达将被分析。在目标2中，他们将确定使用BQ-123治疗的GEE是否会导致冠状动脉和脑血管中ET-1和MMP-9的升高。分析MMP9和TIMP的表达及细胞定位。在目标3中，研究人员将阐明oxLDL信号通过凝集素样oxLDL受体(LOX-1)在调节ET-1和MMP9的诱导中的作用，以响应通过抗LOX-1抗体表达下调而暴露于GEE的反应。在目标4中，他们将确定暴露于常见环境空气污染物(GEE、柴油废气、木烟)是否会导致循环生物标记物--基质金属蛋白酶-9和可溶性LOX-1在小鼠和人类样本中的表达。相关性：考虑到当今动脉粥样硬化、急性心肌梗死和中风给医疗保健带来的沉重负担，确定与这些疾病的启动和/或进展有关的环境因素和分子途径至关重要，这些因素和分子途径可能成为治疗的靶点。

DESCRIPTION (provided by applicant) Atherosclerosis, an inflammatory 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 incidence; however the cellular pathways involved are unknown. Remodeling of arterial extracellular matrix (ECM) is a crucial step in the progression of atherosclerosis, which is primarily regulated through matrix metalloproteinase (MMP) activity. The investigators have reported elevated vascular MMP-9 associated with inhalational exposure to gasoline 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, gasoline engine emissions (GEE), 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, the investigators will utilize atherosclerosis-prone ApoE knockout mice. In Aim 1, they will investigate the molecular pathways involved in ET-1-mediated expression of vascular MMP-9, and regulation of MMP tissue inhibitors (TIMPs), following exposure to GEE, through use of an ET-1receptor antagonist (BQ-123) and a MMP inhibitor, respectively. Resulting MAPK pathway ERK1/2, p38, and JNK expression will be analyzed. In Aim 2, they will determine whether GEE results in elevated ET-1and 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, the investigators 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 GEE by anti-LOX-1 antibody expression knockdown. In Aim 4, they will determine whether exposure to common environmental air pollutants (GEE, diesel exhaust, wood-smoke) results in expression of circulating biomarkers, MMP-9 and soluble LOX-1, in murine and human samples. Relevance: Considering the overwhelming burden of atherosclerosis, AMI, and stroke on healthcare today, it is critical to identify environmental factors and molecular pathways involved in the initiation and/or progression of such diseases, which may serve as targets for therapy.