The Role of Tenascin in Neointimal Formation

描述（由申请人提供）：我们和其他人以前的研究使用细胞培养系统来建立TN的血管功能。我们现在已经在体内扩展了这些观察结果，以检验载脂蛋白E-/-背景中TN的基因缺失可能改变损伤动脉和动脉粥样硬化病变中的新生内膜增生的假设。TN/E-小鼠在喂食高脂肪饮食一周后发生动脉粥样硬化病变。这种病变发展比在Apo E小鼠中观察到的病变发展更快、更复杂。同时，在单独的TN/E组中检测到VCAM- 1表达。流式细胞仪分析显示TN/E来源的内皮细胞VCAM-1表达水平明显高于apo E小鼠。最后，在内皮细胞中，当TNF-α诱导时，发现TN下调VCAM-1启动子活性。这些数据表明，TN缺乏促进白细胞/内皮细胞的相互作用。除了斑块的快速发展外，TN/E小鼠的慢性高脂血症导致不稳定斑块的形成。来自两种小鼠基因型的慢性高脂血症血浆的抗体阵列和ELISA分析表明，与apo E小鼠相比，TN/E组中的嗜酸性粒细胞趋化因子（一种CC趋化因子）选择性上调4至5倍。TN/E组不稳定病灶外膜有肥大细胞聚集。总的来说，我们的数据表明TN在血管疾病中具有抗炎作用。本提案的总体目标是测试4个特定假设（目标）。- 目标1。TN的特定结构域/片段负调控TNF-α诱导的VCAM-1启动子活性。目标2. TN/E小鼠慢性高脂血症上调嗜酸性粒细胞趋化因子，促进肥大细胞的积累。目标3. TN缺乏促进血管损伤后新生内膜形成。目标4。TN缺乏本身足以形成新生内膜。

DESCRIPTION (provided by applicant): Previous investigations by us and others have used a cell culture system to establish the vascular function of TN. We have now extended these observations in vivo to test the hypothesis that the genetic deletion of TN in the apo E-/- background might modify neointimal hyperplasia in an injured artery, and in atherosclerotic lesions. TN/E-mice developed atherosclerotic lesions one-week after being fed on a high fat diet. This lesion development was more rapid and more complex than was observed with Apo E mice. Concomitantly, VCAM- 1 expression was detected in the TN/E group alone. FACS analysis revealed that the VCAM-1 expression level in TN/E-derived endothelial cells was markedly higher than that from apo E mice. Finally, TN was found to down-regulate VCAM-1 promoter activity when induced by TNF-a in endothelial cells. These data suggest that TN deficiency promotes leukocyte/endothelial cell interaction. In addition to the rapid development of plaque, chronic hyperlipidemia in TN/E mice resulted in the formation of unstable plaques. The antibody array and ELISA analyses of chronic hyperlipidemic plasma from the two mouse genotypes showed that eotaxin, a CC chemokine, is selectively upregulated by 4- to 5-fold in the TN/E groups when compared to apo E mice. Furthermore, there was an accumulation of mast cells in the adventitia of unstable lesions in TN/E group. Collectively, our data point to an anti-inflammatory role for TN in vascular diseases. The overall goal of this proposal is to test 4 specific hypotheses (Aims). - Aim 1. A specific domain/segment of TN negatively regulates TNF-a induced VCAM-1 promoter activity. Aim 2. Chronic hyperlipidemia in TN/E mice up-regulates eotaxin promoting an accumulation of mast cells. Aim 3. TN deficiency promotes neointimal formation after vascular injury. Aim 4. TN deficiency per se is sufficient for neointimal formation.