The role of TFEB in aortic aneurysms

摘要 腹主动脉瘤(AAA)破裂后死亡率很高。到目前为止，除了外科手术 干预--只有10%的患者符合条件--没有其他治疗方法可用。 因此，寻找在体内有效治疗或预防AAA的新策略具有重要意义。 血管平滑肌细胞(VSMCs)在维持血管壁的完整性和功能方面起着至关重要的作用 AAA患者VSMC动态平衡被破坏。转录因子EB(TFEB)是溶酶体的主要调节因子 生物发生和自噬。然而，TFEB在VSMC功能和AAA形成中的作用仍有待研究 探索过了。我们发现TFEB能抑制VSMCs的凋亡、MMP2/9活性和炎症反应。VSMC 在小鼠AAA模型中，特异性TFEB基因敲除(KO)显著加剧了血管壁基质的降解。 油酸(OA-NO2)和亚油酸(LNO2)等脂肪酸的硝基烯烃衍生物具有深刻的保护作用 对心血管和代谢性疾病的影响。共轭亚油酸(CLA)被鉴定为 优先和主要硝化的内源性脂肪酸，在人体和实验中很容易生物利用 CLA和无机亚硝酸盐(NO2)的口服模型，使其成为治疗CVD的有吸引力的干预措施。我们 发现硝基共轭亚油酸对血管紧张素Ⅱ诱导的AAA小鼠模型的AAA形成有保护作用并抑制 VSMC炎症和凋亡以TFEB依赖的方式发生。它还促进TFEB核转位 体外以H148依赖的方式提示TFEB是硝基CLA的直接靶标。基于这些 证据，我们将检验中心假设，即TFEB通过促进内源生产而激活 硝基共轭亚油酸通过抑制VSMC功能障碍来保护AAA的形成。通过利用 我们专门为这些研究制作的独特的动物模型，以及 集合团队，我们提出三个目标。目的1：研究VSMC TFEB在AAA形成中的保护作用。 我们将测试我们的工作子假设，即VSMC TFEB通过抑制AAA的形成来防止AAA的形成 VSMC功能障碍。目的：确定硝基共轭亚油酸激活TFEB对体外培养的VSMC功能的抑制作用。 工作亚假说是，硝基共轭亚油酸以TFEB依赖的方式预防VSMC功能障碍。目标 3.确定TFEB为体内硝基共轭亚油酸抑制AAA形成的新治疗靶点。工作小组- 假说是，内源性硝基共轭亚油酸的产生通过激活 VSMC TFEB。综上所述，我们将表征TFEB在AAA形成中的保护作用并建立 Nitro-CLA通过靶向VSMC TFEB而成为治疗AAA的新策略。这项机械论研究 将为硝基共轭亚油酸的快速转化为临床应用奠定坚实的基础，并可能导致 在治疗或/和预防AAA方面取得突破。

ABSTRACT Abdominal Aortic aneurysm (AAA) results in very high mortality upon rupture. To date, besides surgical intervention –with only 10% of patients eligible-, no alternative therapeutic approaches are available. Therefore, it would be of high significance to identify novel strategies to effectively treat or prevent AAA in vivo. Vascular smooth muscle cells (VSMCs) are crucial in maintaining vascular wall integrity and function and VSMC homeostasis is disrupted in AAA. Transcription factor-EB (TFEB) is a “master” regulator of lysosomal biogenesis and autophagy. However, the role of TFEB in VSMC functions and AAA formation remain to be explored. We demonstrated that TFEB inhibits apoptosis, MMP2/9 activity and inflammation in VSMCs. VSMC specific TFEB knockout (KO) significantly aggravates vascular wall matrix degradation in a mouse AAA model. Nitroalkene derivatives of fatty acids such as oleic (OA-NO2) and linoleic acid (LNO2) have profound protective effects against cardiovascular and metabolic diseases. Conjugated linoleic acid (CLA) was identified as the preferential and major nitrated endogenous fatty acid and is readily bioavailable in humans and experimental models upon oral delivery of CLA and inorganic nitrite (NO2), making it an attractive intervention for CVD. We found that nitro-CLA protects against AAA formation in the Ang II-induced AAA mouse model and inhibits VSMC inflammation and apoptosis in a TFEB-dependent manner. It also promotes TFEB nuclear translocation in vitro in an H148-dependent fashion suggesting that TFEB is a direct target of nitro-CLA. Based on these evidences, we will test the central hypothesis that activation of TFEB by enhancing the endogenous production of nitro-CLA protects against AAA formation through inhibition of VSMC dysfunction. By taking advantage of our unique animal models generated specifically for these studies and the combined expertise of the assembled team, we propose 3 aims. Aim 1: Characterize the protective role of VSMC TFEB in AAA formation. We will test our working sub-hypothesis that VSMC TFEB protects against AAA formation through inhibition of VSMC dysfunction. Aim 2: Determine that activation of TFEB by nitro-CLA inhibits VSMC dysfunction in vitro. The working sub-hypothesis is that nitro-CLA prevents VSMC dysfunction in a TFEB-dependent manner. Aim 3: Define TFEB as a novel therapeutic target for nitro-CLA inhibition of AAA formation in vivo. The working sub- hypothesis is that endogenous production of nitro-CLA protects against AAA formation through activation of VSMC TFEB. In summary, we will characterize the protective role of TFEB in AAA formation and establish nitro-CLA as a novel therapeutic strategy against AAA by targeting VSMC TFEB. This mechanistic research will set a solid foundation for rapid translation into clinical utilization of nitro-CLA and may lead to a breakthrough for treatment or/and prevention of AAA.