IL1β Promotes Atheroprotective Changes in Late Stage Atherosclerotic Lesions

项目摘要：不稳定的动脉粥样硬化性病变，包括心肌破裂引起的并发症 脑梗塞和中风是世界范围内的主要死亡原因。尽管进行了数十年的研究，但这些机制和 导致斑块破裂的因素仍然知之甚少。一般认为，皮损具有较高的光滑度 肌细胞(SMC)与巨噬细胞(Mϕ)的比例不太可能破裂。然而，在动脉粥样硬化的背景下，SMC 下调其特征标记和其他细胞类型的表达标记，因此无法使用 传统的记号笔。事实上，我们实验室使用MYH11 ERT2 Cre EYFP ApoE-/-小鼠进行的严格的SMC血统追踪研究 已经表明，病变内80%的SMC缺乏以前用于鉴定它们的标志物的表达 其中近30%的细胞激活了多个M-ϕ标志物。因此，SMC的数量在 损伤不仅被严重低估，而且许多被认为是Mϕ的细胞实际上是SMC来源的。偶数的 更有意义的是，我们发现SMC特异性的条件敲除干细胞多能性基因Klf4和 Oct4对病变的发病机制产生了深远的影响，包括斑块稳定性的多项指标的改变。 然而，与SMC总是具有动脉粥样硬化保护作用的教条相反，我们证明了它们可以是 抗动脉粥样硬化或促进动脉粥样硬化取决于其表型转变的性质。总而言之，研究 强调确定促进SMC表型有益变化的因素和机制的重要性。 一项正在进行的临床试验正在调查高危心血管患者中和白细胞介素1的情况。这个 最重要的假设是炎症导致动脉粥样硬化，而对炎症的抑制将会改善。 病人存活率。然而，缺乏临床前证据表明中和IL1会带来有益的效果。 在晚期动脉粥样硬化的背景下。事实上，我们实验室最近的研究表明，包括申请人在内的 诺华IL-1中和抗体治疗MYH11ERT2 Cre EYFP ApoE-/-小鼠 晚期动脉粥样硬化的建立导致与斑块稳定性降低一致的多种变化 包括显著减少纤维帽内SMC来源的EYFP+细胞的数量，并取代 这些具有Mϕ的细胞。这项建议中的研究将检验这一假设，即SMC中的IL1信号对 晚期动脉粥样硬化斑块稳定性的维持。目标1检验这样一个假设，即 抗白介素1抗体治疗晚期动脉粥样硬化主要通过血管内皮细胞中白介素1受体1信号转导而实现 这会导致病变的SMC发生有害的表型转变。目标2将检验增加产量的假设 抗IL-1单抗治疗晚期皮损MYH11ERT2 Cre EYFP ApoE-/-小鼠后IL-4的变化 在我们最初观察到的晚期病变发病机制中，抗IL-1抗体治疗的有害影响是有贡献的 学习。这些研究将大大增加我们对晚期动脉粥样硬化中IL1信号的理解，并可能 确定加强现有疗法以促进SMC表型和动脉粥样硬化保护改变的方法 最终改善患者的预后。

PROJECT SUMMARY: Complications resulting from rupture of unstable atherosclerotic lesions, including myocardial infarction and stroke, are the leading cause of death worldwide. Despite decades of research, the mechanisms and factors leading to plaque rupture remain poorly understood. It is generally accepted that lesions with a high smooth muscle cell (SMC) to macrophage (Mϕ) ratio are less likely to rupture. However in the setting of atherosclerosis, SMC down-regulate their characteristic markers and express markers of other cells types and thus are undetectable using traditional markers. Indeed, rigorous SMC lineage tracing studies by our lab using Myh11 ERT2Cre eYFP ApoE-/- mice have shown that >80% of SMC within lesions lack expression of the markers previously used for their identification and that nearly 30% of these cells have activated multiple markers of Mϕ. Therefore, the number of SMC within lesions has not only been grossly underestimated, but many cells thought to be Mϕ are actually SMC-derived. Of even greater significance, we showed that SMC-specific conditional knockout of the stem cell pluripotency genes Klf4 and Oct4 had a profound impact on the pathogenesis of lesions including alterations in multiple indices of plaque stability. However, contrary to the dogma that SMC are always atheroprotective, we showed they can be either atheroprotective or -promoting depending on the nature of their phenotypic transitions. Taken together, studies highlight the importance of identifying factors and mechanisms that promote beneficial changes in SMC phenotype. An ongoing clinical trial is investigating neutralization of interleukin-1 in high-risk cardiovascular patients. The overarching hypothesis is that inflammation drives atherosclerosis, and that inhibition of inflammation will improve patient survival. However, there is a lack of preclinical evidence that neutralization of IL1 will confer beneficial effects in the setting of advanced atherosclerosis. Indeed, recent studies from our lab, which included the applicant, showed that treatment of our Myh11 ERT2Cre eYFP ApoE-/- mice with the Novartis IL1-neutralizing antibody after the establishment of advanced atherosclerosis resulted in multiple changes consistent with reduced plaque stability including marked reductions in the number of SMC-derived eYFP+ cells within the fibrous cap, and replacement of these cells with Mϕ. Studies in this proposal will test the hypothesis that IL1 signaling in SMC is critical for maintenance of plaque stability in late-stage atherosclerosis. Aim 1 test the hypothesis that the detrimental effects of anti-IL1 Ab treatment on late-stage atherosclerosis are primarily mediated through IL1R1 signaling in SMC and that this results in deleterious phenotypic transitions in lesion SMC. Aim 2 will test the hypothesis that increased production of interleukin-4 (IL4) following anti-IL1 Ab treatment of Myh11 ERT2Cre eYFP ApoE-/- mice with advanced lesions contributes to the deleterious effects of anti-IL1 Ab treatment on late-stage lesion pathogenesis observed in our initial studies. These studies will greatly increase our understanding of IL1 signaling in late-stage atherosclerosis and may identify approaches to augment current therapies to promote atheroprotective changes in SMC phenotypes and ultimately improve patient outcomes.