Role of IL1b in Regulating SMC and Macrophage Differentiation in Atherosclerosis

描述（由申请人提供）：动脉粥样硬化是一种慢性炎症性疾病，是发达国家发病和死亡的主要原因。然而，我们对导致其发展的潜在机制以及终末期临床事件（包括斑块破裂伴可能的心肌梗死或卒中）的认识仍存在根本性差距。尽管该领域的教条是病变内平滑肌细胞（SMC）与巨噬细胞的比例增加可促进斑块稳定性，但该模型的实验证据存在重大局限性，包括关于病变内哪些细胞是SMC与单核细胞-巨噬细胞来源以及控制SMC和巨噬细胞数量和表型的机制的重大模糊性。具有重要意义的是，采用欧文斯实验室开发的独特SMC谱系追踪ApoE-/-小鼠的研究提供了证据，表明在Mac 2+但SMC标记物（包括SM β-肌动蛋白（SM β A））阴性的晚期病变中，约25%的细胞是SMC-而不是巨噬细胞来源的。相反，一个显着的比例SM�A+纤维帽细胞，推测是SMC衍生的，不是。此外，我们有证据表明，相当一部分巨噬细胞衍生的细胞显示巨噬细胞标志物表达减少，但为SM？A+。总的来说，结果表明，巨噬细胞可以转化为SMC样细胞，SMC转化为巨噬细胞样细胞。此外，结果表明，许多人可能 在该领域的先前研究中，损伤细胞被错误地识别，因此极大地混淆了我们对调节这些细胞的表型转变的机制和因子的理解。该基金的中心重点是确定IL 1 β和IL 1 R1信号传导的遗传或药理学抑制对SMC和巨噬细胞表型转变的影响，以及对晚期动脉粥样硬化病变的总体大小和稳定性的影响。然而，有充分的证据表明，IL 1 β信号的破坏抑制了脂肪条纹的形成， 虽然IL-1在晚期病变中的作用尚不清楚。目的1a将使用我们实验室产生的新的利用SMC和髓系特异性谱系示踪的IL 1 R1敲除小鼠系来检验以下假设：在晚期动脉粥样硬化病变中，SMC和巨噬细胞表型的IL 1 R1依赖性转变在确定总体斑块和管腔大小以及病变组成（包括斑块稳定性的多个指标）中起关键作用。目的1b是确定在我们的小鼠研究中观察到的表型转变是否发生在人类动脉粥样硬化病变中，这是基于使用我们实验室最近开发的高度新颖的表观遗传SMC谱系追踪方法（Gomez et al.，Nature Methods）。目的2将确定用诺华小鼠抗IL 1 β抗体治疗ApoE缺失小鼠是否会诱导病变大小、细胞组成或斑块稳定性指数的变化，以及SMC和/或巨噬细胞表型的转变。

DESCRIPTION (provided by applicant): Atherosclerosis is a chronic inflammatory disease and is the leading cause of morbidity and death in developed countries. However, there are still fundamental gaps in our knowledge of the underlying mechanisms that contribute to its development, and end-stage clinical events including plaque rupture with possible myocardial infarction or stroke. Although the dogma in the field is that an increased ratio of smooth muscle cells (SMC) to macrophages within lesions promotes plaque stability, there are major limitations in the experimental evidence for this model including major ambiguities regarding which cells within lesions are of SMC versus monocyte-macrophage origin and the mechanisms that control SMC and macrophage number and phenotype. Of major significance, studies employing unique SMC lineage tracing ApoE-/- mice developed by the Owens lab provide evidence that ~25% of cells within advanced lesions that are Mac2+ but negative for SMC markers including SM �-actin (SM�A), are SMC- rather than macrophage-derived. Conversely, a significant fraction of SM�A+ fibrous cap cells, presumed to be SMC-derived, are not. Moreover, we have evidence in that a significant fraction of macrophage- derived cells show reduced macrophage marker expression but are SM�A+. Collectively, results show that macrophages may convert to SMC-like cells and SMC to macrophage-like cells. Moreover, results indicate that it is likely that many lesion cells have been mis-identified in previous studies in the field, thus greatly confounding our understanding of the mechanisms and factors that regulate phenotypic transitions of these cells. The central focus of this grant is to determine the effects of genetic or pharmacological inhibition of IL1� and IL1R1 signaling on phenotypic transitions of SMC and macrophages, as well as on the overall size and stability of late stage atherosclerotic lesions. Whereas there is good evidence that disruption of IL1� signaling inhibits formation of fatty streaks and early stage lesions, the role of IL1 in late stage lesions is unclear. Aim 1a will use novel utilize SMC and myeloid specific lineage tracing IL1R1 knockout mouse lines generated by our lab to test the hypothesis that IL1R1-dependent transitions in phenotype of SMC and macrophages within advanced atherosclerotic lesions play a critical role in determining overall plaque and lumen size, as well as lesion composition including multiple indices of plaque stability. Aim 1b will be o determine if phenotypic transitions observed in our mouse studies occur in human atherosclerotic lesions based on analysis of autopsy specimens using a highly novel epigenetic SMC lineage tracing method recently developed by our laboratory (Gomez et al., Nature Methods). Aim 2 will determine if treatment of ApoE null mice with a Novartis mouse anti-IL1� antibody induces changes in lesion size, cellular composition, or indices of plaque stability, as well as transitions in SMC and/or macrophage phenotype.