Colonnello Jamie S, Hance Kirk A, Shames Murray L, Wyble Charles W, Ziporin Scott J, Leidenfrost Jeremy E, Ennis Terri L, Upchurch Gilbert R, Thompson Robert W
Department of Surgery, Section of Vascular Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Vasc Surg. 2003 Jul;38(1):138-46. doi: 10.1016/s0741-5214(03)00125-3.
Abdominal aortic aneurysm (AAA) is associated with chronic transmural inflammation and destruction of the elastic media. The purpose of this study was to elucidate molecular mechanisms that might orchestrate leukocyte recruitment into the outer aortic wall by determining whether CC chemokines contribute to development of aneurysm degeneration in an elastase-induced mouse model of AAA.
Adult male C57BL/6J mice underwent transient elastase perfusion of the abdominal aorta to induce development of AAA. At various intervals after elastase perfusion (0, 4, 7, 14 days), real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assays were used to measure aortic wall expression of the CC (beta) chemokines, monocyte chemoattractant protein-1 (MCP-1) and regulated on activation, normal T-cell expressed and secreted (RANTES). Expression of these chemokines by cultured mouse aortic smooth muscle cells (AoSMC) was similarly assessed after transient (5 minutes) exposure to elastase solutions in vitro.
Mouse aortic diameter (mean +/- SEM) increased to aneurysmal proportions by 14 days after elastase perfusion (from 0.51 +/- 0.03 mm to 1.34 +/- 0.32 mm; 163% increase; P <.05), with macrophage infiltration of the outer aortic wall beginning within 7 to 10 days. Increased aortic wall messenger RNA expression for MCP-1 (28-fold) and RANTES (11-fold) was observed on day 4, with maximal production of chemokine protein on day 7 (MCP-1, from 7.07 +/- 0.06 ng/mL to 19.60 +/- 0.19 ng/mL; P <.001; RANTES, from 0.23 +/- 0.006 ng/mL to 2.03 +/- 0.057 ng/mL; P <.001). Neither MCP-1 nor RANTES was detected in normal mouse aorta with immunohistochemistry, but both chemokines were abundant in AAA. Within 48 hours of transient exposure to elastase, cultured mouse AoSMC exhibited pronounced induction (>90-fold) of MCP-1 and RANTES, despite concomitant decrease in cell numbers.
Increased mouse aortic wall expression of MCP-1 and RANTES occurs early in development of elastase-induced AAA and before onset of the chronic inflammatory response. Moreover, elastase directly stimulates AoSMC chemokine production in vitro. Elastase-induced medial SMC production of CC chemokines may therefore provide an important link between enzymatic injury, leukocyte recruitment, and aneurysmal degeneration of the aortic wall.
腹主动脉瘤（AAA）与慢性透壁性炎症及弹性中膜破坏相关。本研究的目的是通过确定CC趋化因子是否促成弹性蛋白酶诱导的AAA小鼠模型中动脉瘤退变的发展，来阐明可能协调白细胞募集至主动脉外壁的分子机制。
成年雄性C57BL/6J小鼠接受腹主动脉短暂弹性蛋白酶灌注以诱导AAA形成。在弹性蛋白酶灌注后的不同时间间隔（0、4、7、14天），采用实时逆转录聚合酶链反应和酶联免疫吸附测定法来测量主动脉壁CC（β）趋化因子、单核细胞趋化蛋白-1（MCP-1）以及活化调节正常T细胞表达和分泌因子（RANTES）的表达。在体外短暂（5分钟）暴露于弹性蛋白酶溶液后，同样评估培养的小鼠主动脉平滑肌细胞（AoSMC）中这些趋化因子的表达。
弹性蛋白酶灌注后14天，小鼠主动脉直径（均值±标准误）增加至动脉瘤大小（从0.51±0.03毫米增至1.34±0.32毫米；增加163%；P<.05），主动脉外壁在7至10天内开始出现巨噬细胞浸润。在第4天观察到主动脉壁中MCP-1（28倍）和RANTES（11倍）的信使核糖核酸表达增加，趋化因子蛋白在第7天产生量最大（MCP-1，从7.07±0.06纳克/毫升增至19.60±0.19纳克/毫升；P<.001；RANTES，从0.23±0.006纳克/毫升增至2.03±0.057纳克/毫升；P<.001）。免疫组织化学在正常小鼠主动脉中未检测到MCP-1和RANTES，但在AAA中这两种趋化因子均大量存在。在短暂暴露于弹性蛋白酶的48小时内，培养的小鼠AoSMC显示出MCP-1和RANTES的显著诱导（>90倍），尽管细胞数量同时减少。
在弹性蛋白酶诱导的AAA发展早期且在慢性炎症反应开始之前，小鼠主动脉壁中MCP-1和RANTES的表达增加了。此外，弹性蛋白酶在体外直接刺激AoSMC趋化因子的产生。因此，弹性蛋白酶诱导的中膜平滑肌细胞产生CC趋化因子可能在酶性损伤、白细胞募集和主动脉壁动脉瘤退变之间提供重要联系。
