Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, BC, Canada.
Inhal Toxicol. 2012 Jul;24(8):518-27. doi: 10.3109/08958378.2012.696221.
We have shown that diesel exhaust (DE) inhalation caused progression of atherosclerosis; however, the mechanisms are not fully understood. We hypothesize that exposure to DE upregulates cyclooxygenase (COX) expression and activity, which could play a role in DE-induced atherosclerosis.
ApoE knockout mice (30-week old) fed with regular chow were exposed to DE (at 200 µg/m(3) of particulate matter) or filtered air (control) for 7 weeks (6 h/day, 5 days/week). The protein and mRNA expression of COX-1 and COX-2 were evaluated by immunohistochemistry analysis and quantitative real-time PCR, respectively. To examine COX activity, thoracic aortae were mounted in a wire myograph, and phenylephrine (PE)-stimulated vasoconstriction was measured with and without the presence of COX antagonists (indomethacin). COX-2 activity was further assessed by urine 2,3-dinor-6-keto PGF(1α) level, a major metabolite of prostacyclin I(2) (PGI(2)).
Immunohistochemistry analysis demonstrates that DE exposure enhanced COX-2 expression in both thoracic aorta (p < 0.01) and aortic root (p < 0.03), with no modification of COX-1 expression. The increased COX-2 expression was positively correlated with smooth muscle cell content in aortic lesions (R(2) = 0.4081, p < 0.008). The fractional changes of maximal vasoconstriction in the presence of indomethacin was attenuated by 3-fold after DE exposure (p < 0.02). Urine 2,3-dinor-6-keto PGF(1α) level was 15-fold higher in DE group than the control (p < 0.007). The mRNA expression of COX-2 (p < 0.006) and PGI synthase (p < 0.02), but not COX-1, was significantly augmented after DE exposure.
We show that DE inhalation enhanced COX-2 expression, which is also associated with phenotypic changes of aortic lesion.
我们已经证明，柴油机废气（DE）吸入会导致动脉粥样硬化进展；然而，其机制尚不完全清楚。我们假设，暴露于 DE 会上调环氧化酶（COX）的表达和活性，这可能在 DE 诱导的动脉粥样硬化中起作用。
给予载脂蛋白 E 基因敲除（ApoE-/-）小鼠（30 周龄）常规饮食，并使其分别暴露于 DE（颗粒物浓度为 200 µg/m³）或过滤空气（对照）中 7 周（每天 6 小时，每周 5 天）。通过免疫组织化学分析和定量实时 PCR 分别评估 COX-1 和 COX-2 的蛋白和 mRNA 表达。为了检测 COX 活性，将胸主动脉安装在一个金属丝肌动描记器中，并在存在和不存在 COX 拮抗剂（吲哚美辛）的情况下测量苯肾上腺素（PE）刺激的血管收缩。通过尿液中 2,3-二去甲-6-酮 PGF1α 水平（前列环素 I2（PGI2）的主要代谢物）进一步评估 COX-2 活性。
免疫组织化学分析表明，DE 暴露增强了胸主动脉（p < 0.01）和主动脉根部（p < 0.03）中 COX-2 的表达，但 COX-1 的表达没有改变。COX-2 表达的增加与主动脉病变中平滑肌细胞含量呈正相关（R² = 0.4081，p < 0.008）。DE 暴露后，加入吲哚美辛后最大血管收缩的分数变化减弱了 3 倍（p < 0.02）。DE 组尿液中 2,3-二去甲-6-酮 PGF1α 水平比对照组高 15 倍（p < 0.007）。DE 暴露后，COX-2（p < 0.006）和 PGI 合酶（p < 0.02）的 mRNA 表达显著增加，但 COX-1 则不然。
我们表明，DE 吸入增强了 COX-2 的表达，这也与主动脉病变的表型变化有关。
