Curfs Daniëlle M J, Knaapen Ad M, Pachen Daniëlle M F A, Gijbels Marion J J, Lutgens Esther, Smook Marjan L F, Kockx Mark M, Daemen Mat J A P, van Schooten Frederik J
Department of Health Risk Analysis and Toxicology, University of Maastricht, Maastricht, The Netherlands.
FASEB J. 2005 Aug;19(10):1290-2. doi: 10.1096/fj.04-2269fje. Epub 2005 Jun 6.
Although it has been demonstrated that carcinogenic environmental polycyclic aromatic hydrocarbons (PAHs) cause progression of atherosclerosis, the underlying mechanism remains unclear. In the present study, we aimed to investigate whether DNA binding events are critically involved in the progression of PAH-mediated atherogenesis. Apolipoprotein E knockout mice were orally (24 wk, once/wk) exposed to 5 mg/kg benzo[a]pyrene (B[a]P), or its nonmutagenic, noncarcinogenic structural isoform benzo[e]pyrene (B[e]P). 32P-postlabeling of lung tissue confirmed the presence of promutagenic PAH-DNA adducts in B[a]P-exposed animals, whereas in B[e]P-exposed and vehicle control animals, these adducts were undetectable. Morphometrical analysis showed that both B[a]P and B[e]P caused an increase in plaque size, whereas location or number of plaques was unaffected. Immunohistochemistry revealed no differences in oxidative DNA damage (8-OHdG) or apoptosis in the plaques. Also plasma lipoprotein levels remained unchanged after PAH-exposure. However, T lymphocytes were increased > or =2-fold in the plaques of B[a]P- and B[e]P-exposed animals. Additionally, B[a]P and to a lesser extent B[e]P exposure resulted in increased TGFbeta protein levels in the plaques, that was mainly localized in the plaque macrophages. In vitro studies using the murine macrophage like RAW264.7 cells showed that inhibition of TGFbeta resulted in decreased tumor necrosis factor (TNF) alpha release, suggesting that enhanced TGFbeta expression in the plaque macrophages contributes to the proinflammatory effects in the vessel wall. In general, this inflammatory reaction in the plaques appeared to be a local response since peripheral blood cell composition (T cells, B cells, granulocytes, and macrophages) was not changed upon PAH exposure. In conclusion, we showed that both B[a]P and B[e]P cause progression of atherosclerosis, irrespective of their DNA binding properties. Moreover, our data revealed a possible novel mechanism of PAH-mediated atherogenesis, which likely involves a TGFbeta-mediated local inflammatory reaction in the vessel wall.
尽管已有研究表明，致癌性环境多环芳烃（PAHs）会导致动脉粥样硬化进展，但其潜在机制仍不清楚。在本研究中，我们旨在探究DNA结合事件是否在PAH介导的动脉粥样硬化发生发展过程中起关键作用。将载脂蛋白E基因敲除小鼠经口（24周，每周一次）暴露于5 mg/kg苯并[a]芘（B[a]P）或其非诱变、非致癌的结构异构体苯并[e]芘（B[e]P）。对肺组织进行32P后标记证实，暴露于B[a]P的动物肺组织中存在前诱变PAH-DNA加合物，而在暴露于B[e]P和赋形剂对照的动物中未检测到这些加合物。形态计量学分析表明，B[a]P和B[e]P均导致斑块大小增加，而斑块的位置或数量未受影响。免疫组织化学显示，斑块中的氧化性DNA损伤（8-OHdG）或细胞凋亡无差异。PAH暴露后血浆脂蛋白水平也保持不变。然而，在暴露于B[a]P和B[e]P的动物斑块中，T淋巴细胞增加了2倍或更多。此外，B[a]P暴露以及程度较轻的B[e]P暴露导致斑块中TGFβ蛋白水平升高，主要定位于斑块巨噬细胞中。使用鼠巨噬细胞样RAW264.7细胞进行的体外研究表明，抑制TGFβ会导致肿瘤坏死因子（TNF）α释放减少，这表明斑块巨噬细胞中TGFβ表达增强有助于血管壁的促炎作用。总体而言，斑块中的这种炎症反应似乎是一种局部反应，因为PAH暴露后外周血细胞组成（T细胞、B细胞、粒细胞和巨噬细胞）未发生变化。总之，我们表明B[a]P和B[e]P均会导致动脉粥样硬化进展，无论它们的DNA结合特性如何。此外，我们的数据揭示了PAH介导的动脉粥样硬化发生发展的一种可能的新机制，这可能涉及血管壁中TGFβ介导的局部炎症反应。
