APOPTOSIS OF SMOOTH MUSCLE CELLS IN CAROTID PLAQUES

描述（由申请人提供）：动脉粥样硬化的发病率和死亡率与斑块破裂引起的复杂动脉粥样硬化病变和严重的半球神经症状有关。然而，由于斑块的稳定性，一组动脉粥样硬化患者仍然无症状。目前尚不清楚稳定斑块和不稳定斑块是否存在生物化学差异，以及免疫系统如何调节斑块的稳定性。在过去的几年里，我们实验室的研究表明胰岛素样生长因子-1 （IGF-1）是一种有效的单核细胞化学引诱剂，对血管平滑肌细胞（VSMCs）具有很强的有丝分裂和抗凋亡活性。此外，我们已经表明，在稳定斑块中，VSMCs密度增加，巨噬细胞和t淋巴细胞数量减少，而在不稳定斑块中则相反。我们提出的假设是，在有症状的患者中观察到，由于增殖和活化的t淋巴细胞（ifn - γ）和巨噬细胞（IL-12和IL-18）释放的细胞因子导致VSMCs上IGF-1受体（IGF-1R）的表达和活性降低，导致细胞凋亡，导致动脉粥样硬化斑块不稳定。为此，在有症状和无症状患者的颈动脉斑块VSMCs中应用的具体目的是：具体目的1：我们将使用TUNEL、膜联蛋白V标记、时间推移视频显微镜和caspase 3活性，在存在和不存在人类动脉粥样硬化相关细胞因子（11-12、IL-18和ifn - γ）的情况下，检查有症状和无症状患者的igf -l诱导斑块VSMCs的存活。为了比较，正常颈动脉的VSMCs将并行运行。特异性目的2：我们将研究细胞因子诱导的igf -l诱导的VSMCs存活降低的潜在机制。我们将评估细胞因子对有症状和无症状颈动脉斑块VSMCs中IGF-1R和igfbp的影响。特异性目的3：我们将研究叉头转录因子FoxO家族，特别是FKHR （FoxO1）和FKHR- l1 (FoxO3)，以及细胞周期蛋白依赖性激酶抑制剂p27kip1和Bim （Bcl-2家族的促凋亡蛋白）在igf -l诱导的有症状和无症状颈动脉斑块的vsmc存活中的作用。更好地了解颈动脉狭窄的病理生理学和IGF-1受体在斑块稳定性中的调节作用，将为开发更精确和更具成本效益的治疗方法提供机会。

DESCRIPTION (provided by applicant): Morbidity and mortality from atherosclerosis are associated with complicated atherosclerotic lesions due to plaque rupture and severe hemispheric neurological symptoms. However, a group of atherosclerotic patients remain asymptomatic because of plaque stability. It is not known if and how the stable and unstable plaques are different biochemically, and how the immune system regulates plaque stability. The studies over the past several years in our laboratory suggest that insulin-like growth factor-1 (IGF-1) is a potent chemoattractant for monocytes, and possess strong mitogenic and anti-apoptotic activity for vascular smooth muscle cells (VSMCs). Furthermore, we have shown that in stable plaques there is increased density of VSMCs and decreased number of macrophages and T-lymphocytes, whereas reverse is true with unstable plaques. We propose the hypothesis that decreased expression and activity of IGF-1 receptors (IGF-1R) on VSMCs due to cytokines released by proliferating and activated T-lymphocytes (IFN-gamma) and macrophages (IL-12 and IL-18) leads to apoptosis resulting in the instability of atherosclerotic plaques observed in symptomatic patients. To these ends the Specific Aims of this application in the carotid plaque VSMCs of both symptomatic and asymptomatic patients are: Specific Aim 1: We will examine IGF-l-induced survival of plaque VSMCs of both symptomatic and asymptomatic patients in the presence and absence of human atheroma-associated cytokines (11-12, IL-18 and IFN-gamma) using TUNEL, annexin V labeling, time-lapse videomicroscopy, and caspase 3 activity. For comparison, VSMCs from normal carotid artery will be run in parallel. Specific Aim 2: We will examine the underlying mechanisms of cytokine-induced decrease in IGF-l-induced survival of VSMCs. We will assess the effect of cytokines on IGF-1R and IGFBPs in VSMCs of symptomatic and asymptomatic carotid plaques. Specific Aim 3: We will investigate the role of FoxO family of forkhead transcription factors, specifically FKHR (FoxO1) and FKHR-L1 (FoxO3), and cyclin-dependent kinase inhibitor p27kip1 and Bim, a pro-apoptotic proteinof Bcl-2 family in IGF-l-induced survival of VSMCs from symptomatic and asymptomatic carotid plaques. A better understanding of the pathophysiology of carotid stenosis and regulatory role of IGF-1 receptors in the stability of plaques will provide opportunities to develop a more precise and cost-effective treatment.