Knaapen Ad M, Curfs Daniëlle M, Pachen Daniëlle M, Gottschalk Ralph W, de Winther Menno P J, Daemen Mat J, Van Schooten Frederik J
Department of Health Risk Analysis and Toxicology, Nutrition and Toxicology Research Institute Maastricht (NUTRIM), The Netherlands.
Mutat Res. 2007 Aug 1;621(1-2):31-41. doi: 10.1016/j.mrfmmm.2006.12.010. Epub 2007 Feb 28.
Exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs) has been implicated in the aetiology of atherosclerosis. Previously we showed that chronic exposure of ApoE-/- mice to the prototype PAH benzo[a]pyrene (B[a]P) causes enhanced progression of atherosclerosis, which was characterised by an increased inflammatory cell content in the atherosclerotic plaques. The aim of the present study was to evaluate the effect of B[a]P on vascular expression of monocyte-chemoattractant protein 1 (MCP-1), which is a crucial molecule promoting the recruitment of monocytes into atherosclerotic lesions. We hypothesised that B[a]P-induced expression of MCP-1 is mediated through aryl hydrocarbon receptor (AhR) activation. Initially we performed in vivo studies showing that acute treatment with B[a]P induces MCP-1 gene expression in aortic tissue of ApoE-/- mice. These observations could be confirmed by in vitro studies with human endothelial cells (RF24 cell line and primary HUVEC), showing a dose- and time-dependent increase in MCP-1 expression upon exposure to B[a]P. This was paralleled by an induction of cytochrome P450 1A1 and 1B1, indicating Ah receptor activation. No increased gene expression (MCP-1, CYP1A1 and 1B1) was found upon incubation with the structural isomer benzo[e]pyrene, which is a weak AhR agonist. Moreover, B[a]P-induced MCP-1 gene and protein expression was inhibited by co-treatment with the AhR antagonist alpha-naphthoflavone. In addition to its effect on basal gene expression, we showed that B[a]P significantly enhanced TNFalpha-induced expression of MCP-1. We were unable to block B[a]P-induced MCP-1 expression by antioxidant treatment. In contrast, we found that addition of N-acetylcysteine or vitamin C enhanced transcription of MCP-1 by B[a]P. In conclusion, our studies revealed potent vascular pro-inflammatory effects of B[a]P, as evidenced by AhR-mediated induction of MCP-1. These observations further contribute to the concept that induction of inflammation is a crucial process in PAH-enhanced atherogenesis.
接触致癌性多环芳烃（PAHs）与动脉粥样硬化的病因有关。此前我们发现，ApoE基因敲除小鼠长期接触原型PAH苯并[a]芘（B[a]P）会导致动脉粥样硬化进展加速，其特征是动脉粥样硬化斑块中的炎症细胞含量增加。本研究的目的是评估B[a]P对单核细胞趋化蛋白1（MCP-1）血管表达的影响，MCP-1是促进单核细胞募集到动脉粥样硬化病变中的关键分子。我们假设B[a]P诱导的MCP-1表达是通过芳烃受体（AhR）激活介导的。最初我们进行了体内研究，结果表明用B[a]P急性处理可诱导ApoE基因敲除小鼠主动脉组织中MCP-1基因表达。这些观察结果可通过用人内皮细胞（RF24细胞系和原代人脐静脉内皮细胞）进行的体外研究得到证实，研究表明接触B[a]P后MCP-1表达呈剂量和时间依赖性增加。同时伴有细胞色素P450 1A1和1B1的诱导，表明Ah受体被激活。与结构异构体苯并[e]芘（一种弱AhR激动剂）孵育后未发现基因表达增加（MCP-1、CYP1A1和1B1）。此外，与AhR拮抗剂α-萘黄酮共同处理可抑制B[a]P诱导的MCP-1基因和蛋白表达。除了对基础基因表达的影响外，我们还发现B[a]P可显著增强肿瘤坏死因子α诱导的MCP-1表达。抗氧化剂处理无法阻断B[a]P诱导的MCP-1表达。相反，我们发现添加N-乙酰半胱氨酸或维生素C可增强B[a]P对MCP-1的转录作用。总之，我们的研究揭示了B[a]P具有强大的血管促炎作用，AhR介导的MCP-1诱导就是明证。这些观察结果进一步支持了炎症诱导是PAH增强动脉粥样硬化发生过程中的关键环节这一观点。
