Human CYP1A1, diet and dioxin-induced hypertension

描述(由申请人提供)：大量证据表明，膳食中的omega-3多不饱和脂肪酸(？-3PUFAs)可预防心血管疾病的发病率和死亡率。尽管美国心脏协会建议所有人都摄入来自鱼或鱼油补充剂的？-3多不饱和脂肪酸，但许多人出于对累积的环境污染物的担忧而避免食用鱼类。众所周知，卤代芳香烃(HAH)污染物在鱼类体内生物积累，研究表明，接触HAH会增加患心血管疾病的风险。暴露在HAHS中高度诱导细胞色素P4501A1(CYP1A1)，值得注意的是，-3多不饱和脂肪酸是CYP1A1的首选内源脂肪酸底物。因此，持续的CYP1A1诱导可以降低β-3多不饱和脂肪酸，从而增加HAH暴露引起的心血管疾病风险。我们的研究表明，接触典型的HAH，2，3，7，8-四氯二苯并-对二恶英(TCDD)，会导致小鼠血管功能障碍和高血压，这些效应需要诱导细胞色素P1A1的诱导。我们的初步数据显示，TCDD暴露小鼠2周(在血压升高之前)高度诱导阻力动脉中的CYP1A1，并耗尽肝脏？-3多不饱和脂肪酸。在野生型(WT)小鼠中，这种暴露还诱导了与？-3PUFA耗竭一致的血管基因表达和内皮衍生收缩因子的产生，但不能诱导基因敲除(KO)小鼠。此外，TCDD增加花生四烯酸(AA)介导的血管收缩，而富含β-3多不饱和脂肪酸的饮食可使这一作用正常化。我们假设，CYP1A1通过？-3PUFA耗竭介导TCDD诱导的血管功能障碍和高血压。我们进一步假设，在体内，人的细胞色素P1A1将和老鼠的细胞色素P1A1一样有效地调节这些反应。为了测试这一点，在目标1中，我们将建立在TCDD诱导的血管脂肪酸和基因/蛋白质表达变化中对CYP1A1的需求，使用CYP1A1 WT和KO小鼠，以及小鼠的CYP1A1和1A2基因已被人的CYP1A1/1A2同源基因(HCYP1A)取代的小鼠。我们将调查变化的时间进程和程度，以及？-3多不饱和脂肪酸预防它们的能力。人源化的CYP1A小鼠将显著提高我们从小鼠到人类的推断能力。在目标2中，我们将通过使用CYP1A1 WT和hCYP1A小鼠，并研究主动脉和肠系膜血管反应性，来确定CYP1A1介导TCDD诱导的血管功能障碍的机制。然后呢？-3个不饱和脂肪酸。在目标3中，我们将利用无线电遥测技术来确定人类细胞色素P4501对TCDD诱导的高血压的调节能力以及饮食中的？-3多不饱和脂肪酸对其的预防作用。如果被证实是正确的，这些研究将提供第一个实验证据，证明？-3多不饱和脂肪酸的益处可以抵消鱼类体内积累的HAH污染物带来的血管疾病风险。这些结果还对人类健康产生了更广泛的影响。特别是，香烟烟雾中含有高水平的HAHS，可诱导CYP1A1，可能导致血管疾病。因此，抑制细胞色素P1A1基因的表达可能成为降低持续诱导细胞色素P1A1基因所致血管疾病风险的新的药物靶点。 与公共健康相关：美国心脏协会承认，食用鱼类可显著预防心血管疾病，这些益处来自于摄入omega-3多不饱和脂肪酸；然而，由于担心累积的环境污染物，许多人避免食用鱼类。虽然人们试图估计食用鱼类的风险-收益比，但还没有实验研究饮食中的omega-3多不饱和脂肪酸、污染物和心血管疾病之间的相互作用。拟议中的研究将使用动物模型来调查饮食中omega-3多不饱和脂肪酸对污染物的保护能力。 这项研究旨在测试鱼源性脂肪酸的益处抵消了鱼类中累积的污染物带来的心血管风险这一前提。

DESCRIPTION (provided by applicant): Considerable evidence demonstrates that dietary omega-3 polyunsaturated fatty acids (?-3 PUFAs) protect against cardiovascular morbidity and mortality. Although the American Heart Association recommends that all individuals consume ?-3 PUFAs from fish or fish oil supplements, many individuals avoid fish consumption due to concern about accumulated environmental pollutants. It is well known that halogenated aromatic hydrocarbon (HAH) pollutants bioaccumulate in fish and studies have linked human HAH exposure to an increased risk of cardiovascular disease. Exposure to HAHs highly induces cytochrome P4501A1 (CYP1A1) and notably, ?-3 PUFAs are the preferred endogenous fatty acid substrates for CYP1A1. Thus, sustained CYP1A1 induction could decrease ?-3 PUFAs, contributing to cardiovascular disease risk resulting from HAH exposure. Our research shows that exposure to a prototypical HAH, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), induces vascular dysfunction and hypertension in mice and these effects require induction of CYP1A1. Our preliminary data show that TCDD exposure of mice for 2 wks (prior to an increase in blood pressure) highly induces CYP1A1 in resistance arteries and depletes hepatic ?-3 PUFAs. This exposure also induces vascular gene expression consistent with ?-3 PUFA depletion and production of endothelial-derived contracting factors in CYP1A1 wildtype (WT), but not knockout (KO) mice. Further, TCDD increases arachidonic acid (AA)-mediated vasoconstriction and an ?-3 PUFA-enriched diet normalizes this effect. We hypothesize that CYP1A1 mediates TCDD-induced vascular dysfunction and hypertension via ?-3 PUFA depletion. We further hypothesize that human CYP1A1 will be as effective as mouse CYP1A1 in mediating these responses in vivo. To test this, in Aim 1 we will establish the requirement for CYP1A1 in TCDD-induced changes in vascular fatty acids and gene/protein expression, using CYP1A1 WT and KO mice, as well as mice where the mouse CYP1A1 and 1A2 genes have been replaced with the human CYP1A1/1A2 orthologs (hCYP1A). We will investigate the time course and magnitude of changes and the ability of ?-3 PUFAs to prevent them. The humanized CYP1A mouse will significantly improve our ability to extrapolate from mice to humans. In Aim 2 we will determine the mechanism by which CYP1A1 mediates TCDD-induced vascular dysfunction, using CYP1A1 WT and hCYP1A mice, and studying the aorta and mesenteric vasoreactivity ? and ?-3 PUFAs. In Aim 3 we will determine the ability of human CYP1A1 to mediate TCDD-induced hypertension and dietary ?-3 PUFAs to prevent it, using radiotelemetry. If proven correct these studies would provide the first experimental evidence that benefits of ?-3 PUFAs can offset vascular disease risk posed by HAH pollutants accumulated in fish. These outcomes also have broader human health implications. In particular, cigarette smoke has high levels of HAHs that induce CYP1A1 potentially contributing to vascular disease. Thus, CY?P1A1 inhibition could be a novel drug target for reducing vascular disease risk as a consequence of sustained CYP1A1 induction. PUBLIC HEALTH RELEVANCE: The American Heart Association recognizes that eating fish provides significant protection from developing cardiovascular disease and these benefits are derived from the intake of omega-3 polyunsaturated fatty acids; however, many individuals avoid fish consumption due to concern about accumulated environmental pollutants. While attempts have been made to estimate a risk-benefit ratio for fish consumption, no studies have experimentally investigated the interaction between dietary omega-3 polyunsaturated fatty acids, pollutants, and cardiovascular disease. The proposed studies will use an animal model to investigate the ability of dietary omega-3 polyunsaturated fatty acids to protect against pollutant induced vascular disease and hypertension, testing the premise that benefits of fish-derived fatty acids offset cardiovascular risk from pollutants accumulated in fish.