Renewal: Pannexin-1 signaling in abdominal aortic aneurysms

项目总结 腹主动脉瘤(AAA)的形成和随后的主动脉破裂可导致猝死，是一种 严重的临床问题，目前尚无已知的治疗方法。AAA患者的特征 包括血栓形成和细胞死亡机制，如细胞凋亡和中性粒细胞胞外陷阱 (篮网)。死亡细胞碎片的清除是通过胞吐作用来调节的，通过这个过程，细胞凋亡 组织被专业吞噬细胞(如巨噬细胞)和非专业吞噬细胞所识别 吞噬细胞(如内皮细胞；ECs)，在AAA的发病机制中仍有待阐明。因此，我们的 假说侧重于导致缺陷的炎症分解途径的失调 胞吐和促进慢性主动脉组织炎症和血管重塑。我们最近的研究表明 血管内皮细胞依赖的pAnnexin-1(Panx1)通道在主动脉形成中的重要作用 炎症和AAA的形成。这一建议的科学前提集中在EC- 通过激活Panx1介导的泡腾作用导致AAA炎症-溶解失衡 进步。因此，这一建议的中心假设是EC的胞吐作用是由于 MerTK是一种识别凋亡细胞的细胞表面酪氨酸激酶受体，它的切割导致 死细胞碎片堆积和血栓形成。其次，我们的机械论研究将剖析 内皮细胞和巨噬细胞之间的动态通讯，涉及缺陷的EC介导的泡腾作用 导致巨噬细胞中铁介导的细胞过度死亡(铁下垂)，这些共同反馈到 导致Panx1激活和慢性炎症循环。我们的支持性数据表明， 主动脉炎症与EC依赖的MerTK表达增加和血管内皮生长因子的吞噬有关 中性粒细胞。此外，缺陷的EC介导的泡腾作用加剧了巨噬细胞的铁下垂(通过 SLC7A11和Nrf2-信号)，反馈导致EC-Panx1激活和eATP释放。总的来说，我们的 结果提示EC介导的泡泡吞噬和巨噬细胞依赖的铁下垂的调节失调 在腹主动脉形成和主动脉破裂过程中造成炎症分解过程的中断。我们会 使用小鼠弹性酶治疗AAA和我们的创新的主动脉破裂的拟议研究 模型，以及通过对我们生物仓库中的人AAA组织进行分析。使用新的可诱导细胞特异性 基因敲除小鼠，如CDH5Cre-ERT2/MerTKfl/fl、MerTKCR(抗卵裂)和Cx3CR1Cre- 在ERT2/SLC7A11fl/fl小鼠中，我们将描述先前未知的调节泡泡吞噬和 AAA形成过程中Panx1通道激活的铁性下垂。我们的研究将提供新的见解 内皮细胞与巨噬细胞相互作用的分子信号机制 在胞吐/铁下垂/Panx1治疗AAA和预防主动脉破裂之间的循环。

PROJECT SUMMARY Abdominal aortic aneurysms (AAA) formation and subsequent aortic rupture can lead to sudden death and is a significant clinical problem with no currently known medical treatments available. The hallmarks of patient AAA include thrombus formation and cell death mechanisms such as apoptosis and neutrophil extracellular traps (NETs). The clearance of dead cell debris is mediated via the process of efferocytosis, by which apoptotic tissue is recognized for engulfment by professional phagocytes (e.g., macrophages) and non-professional phagocytes (e.g., endothelial cells; ECs), and remains to be elucidated in the pathogenesis of AAA. Thus, our hypothesis focuses on the dysregulation of inflammation-resolution pathways that lead to to defective efferocytosis and promote chronic aortic tissue inflammation and vascular remodeling. Our recent study has demonstrated a critical role orchestrated by EC-dependent pannexin-1 (Panx1) channels in causing aortic inflammation and AAA formation. The scientific premise of this proposal focuses on the dysregulation of EC- mediated efferocytosis causing an imbalance of inflammation-resolution via Panx1 activation in AAA progression. Therefore, the central hypothesis in this proposal is that EC efferocytosis is dysregulated due to cleavage of MerTK, a cell surface tyrosine kinase receptor that recognizes apoptotic cells, leading to accumulation of dead cell debris and thrombus formation. Second, our mechanistic studies will dissect the dynamic communication between ECs and macrophages, involving defective EC-mediated efferocytosis leading to excessive iron-mediated cell death (ferroptosis) in macrophages, that collectively feedbacks to cause Panx1 activation and an chronic inflammatory loop. Our supportive data demonstrates that resolution of aortic inflammation is associated with increased EC-dependent MerTK expression and efferocytosis of neutrophils. Furthermore, defective EC-mediated efferocytosis exacerbates ferroptosis in macrophages (via SLC7A11 and Nrf2-signaling) that feedbacks to cause EC-Panx1 activation and eATP release. Collectively, our results suggest that dysregulation of EC-mediated efferocytosis and macrophage-dependent ferroptosis creates a break in the inflammation-resolution process during AAA formation and aortic rupture. We will delineate the proposed studies using the murine elastase-treatment AAA and our innovative aortic rupture model, as well as by analysis of human AAA tissue from our biorepository. Using novel inducible cell-specific genetic knockout mice such as Cdh5Cre-ERT2/MerTKfl/fl, MerTKCR (cleavage-resistant), and Cx3CR1Cre- ERT2/SLC7A11fl/fl mice, we will delineate the previously unknown mechanisms of dysregulated efferocytosis and ferroptosis in activation of Panx1 channels during AAA formation. Our studies will provide novel insight into mechanisms of molecular signaling interactions between ECs and macrophages to define the inflammatory loop between efferocytosis/ferroptosis/Panx1 for the treatment of AAAs and prevention of aortic rupture.