Suppression of vascular endothelial cell inflammation

描述(申请人提供)：抑制血管内皮细胞炎症适应性免疫和先天免疫严密调节动脉粥样硬化。血管内皮细胞是促炎症细胞因子的靶点，如白介素1b(IL-1b)和肿瘤坏死因子-a(TNF-a)。然而，血管内皮细胞是否在引发血管炎症中发挥关键作用这一重要问题仍然没有明确的定义。特别是，动脉粥样硬化条件下的内皮细胞是否通过新定义的炎症体产生过量的IL-1b的问题仍然未知。因此，这项提议的目的是检验一种新的假说，即在动脉粥样硬化的发病机制中，伴随着IL-1b的产生和EC的凋亡而加速的EC炎症。推论认为，抑制内皮细胞产生过量IL-1b的因子和细胞以及内皮细胞的凋亡在动脉粥样硬化形成中起抑制作用。我们实验室的初步数据和其他实验室的报告清楚地支持这一假设：(I)微生物感染在动脉粥样硬化的发病机制中发挥了作用。在细菌脂多糖(LPS)刺激下，载脂蛋白E基因缺陷小鼠的小鼠主动脉内皮细胞(MAECs)比野生型对照小鼠的MAECs表达更高水平的前IL-1b。在磷脂酰肌醇3-激酶(PI-3K)抑制剂Wortmannin和Ly294002的存在下，ApoE-/-小鼠MAECs中前-IL-1b的上调被增加，这表明PI3K-Akt生存途径抑制了IL-1b产生的EC炎症；(Ii)我们已经鉴定出一种新的Bcl-XL相互作用的抗凋亡蛋白TCTP。TCTP是PI3K-Akt生存通路中重要的调节蛋白和抗凋亡蛋白。此外，内皮细胞中TCTP表达下调，提示抗TCTP可能作为PI-3K-Akt通路信号转导的内皮细胞保护机制，抑制内皮细胞的炎症和凋亡。此外，我们还发现，ApoE-/-小鼠MAEC与CD4+CD25HighFoxp+调节性T细胞(Tregs)共培养后，对内毒素的反应降低了前IL-1b的表达，提示免疫抑制Tregs抑制EC的炎症；(Iii)IL-1b缺乏抑制EC的炎症和动脉粥样硬化。因此，阐明IL-1b产生的EC炎症和EC细胞凋亡的抑制机制具有重要的临床意义，可能为动脉粥样硬化和血管炎症的治疗开辟新的途径。这一目标将通过执行下列特定目标来实现：(1)确定与野生型对照小鼠相比，致动脉粥样硬化ApoE-/-小鼠中是否加速了产生IL-1b的EC炎症；(2)确定TCTP和PI3K-Akt细胞内信号通路是否抑制ApoE-/-小鼠中产生IL-1b的EC炎症和EC凋亡；以及(3)确定Tregs对ApoE-/-小鼠中产生IL-1b的EC炎症和EC凋亡的细胞外抑制是否减轻了ApoE-/-小鼠的动脉粥样硬化。公共卫生相关性：越来越多的证据表明，血管内皮细胞(ECs)炎症在动脉粥样硬化的发展中起着重要作用。然而，血管内皮细胞是否在引发血管炎症中发挥关键作用这一重要问题仍然没有明确的定义。这些研究将提供更好的理解，阐明产生IL-1b的EC炎症和EC凋亡的抑制机制是否能导致开发治疗动脉粥样硬化和血管细胞炎症的新疗法。

DESCRIPTION (provided by applicant): Suppression of vascular endothelial cell inflammation both adaptive and innate immunity tightly regulate atherosclerosis. Vascular endothelial cells (ECs) are targets of proinflammatory cytokines, such as interleukin-1b (IL-1b) and tumor necrosis factor-a (TNF-a). However, the important question of whether ECs play a critical role in initiating vascular inflammation remains poorly defined. In particular, the issue of whether ECs in atherogenic conditions generate excess IL-1b via the newly-defined inflammasome remains unknown. Therefore, the goal of this proposal is to examine a novel hypothesis that EC inflammation with the generation of IL-1b followed by EC apoptosis is accelerated in the pathogenesis of atherosclerosis. The corollary hypothesis is that factors and cells in suppressing EC generation of excess IL- 1b and EC apoptosis play inhibitory roles in atherogenesis. Preliminary data from our lab and reports from others' labs clearly support this hypothesis: (i) Microbial infections play a role in the pathogenesis of atherosclerosis. In response to the stimulation of bacterial lipopolysaccharide (LPS), mouse aortic ECs (MAECs) from atherogenic apolipoprotein E-deficient ApoE-/- mice express higher levels of pro-IL-1b than MAECs from wild-type control mice. The upregulation of pro-IL-1b in MAECs from ApoE-/- mice is increased in the presence of phosphatidylinositol 3-kinase (PI-3K) inhibitors Wortmannin and Ly294002, suggesting that PI3K-Akt survival pathway suppresses IL-1b-generating EC inflammation; (ii) We have identified a novel Bcl-xL interacting, anti-apoptotic protein TCTP. TCTP is an important regulator and anti-apoptotic protein along PI3K- Akt survival pathway. In addition, TCTP is also down-regulated in response to LPS stimulation in ECs, suggesting that anti-TCTP may inhibit EC inflammation and apoptosis as a PI-3K-Akt pathway-signaled protective mechanism of ECs. In addition, we found that co-culture of MAECs from ApoE-/- mice with CD4+CD25highFoxp+ regulatory T cells (Tregs) results in decreased pro-IL-1b expression in response to LPS, suggesting that immunosuppressive Tregs suppress EC inflammation; (iii) IL-1b deficiency inhibits EC inflammation and atherogenesis. Therefore, the elucidation of the suppressive mechanisms of IL-1b-generating EC inflammation and EC apoptosis is clinically significant, as it may lead to new therapeutics for treating atherosclerosis and vascular inflammation. This goal will be pursued through the execution of the following specific aims: (1) To determine whether IL-1b-generating EC inflammation is accelerated in atherogenic ApoE-/- mice in comparison to that in wild-type control mice; (2) To determine whether TCTP and PI3K-Akt intracellular signaling pathway inhibits IL-1b-generating EC inflammation and EC apoptosis in ApoE-/- mice; and (3) To determine whether extracellular suppression of IL-1b-generating EC inflammation and EC apoptosis by Tregs attenuates the atherogenesis in ApoE-/- mice. PUBLIC HEALTH RELEVANCE: There is increasing evidence that vascular endothelial cell (ECs) inflammation significantly contributes to the development of atherosclerosis. However, the important question of whether ECs play a critical role in initiating vascular inflammation remains poorly defined. The proposed studies will provide better understanding whether the elucidation of the suppressive mechanisms of IL-1b-generating EC inflammation and EC apoptosis can lead to the development of new therapeutics for treating atherosclerosis and vascular cell inflammation.