Establishing basic biological mechanisms governing cardiovascular benefits

之前的NSERC Discovery Grant使我们能够在大鼠心脏移植模型中了解饮食制剂和抗排斥药物的潜在协同效应。因此，在拟议的研究中，我们希望利用我们的经验来进一步提高我们对转基因小鼠模型移植冠状动脉粥样硬化发生和预防的基本机制的了解。这些研究将包括以下3个目标：目标1：心血管益处，包括预防心脏移植后饮食植物类固醇和亚硝酸盐的并发症，是通过改变免疫系统来实现的。我们将在小鼠身上进行心脏移植手术。在手术完全恢复后，这些小鼠将接受为期12周的实验饮食治疗，其中包括单独含有植物类固醇的饮食，或含有亚硝酸盐或普罗布考的饮食。饮食中的植物甾醇和亚硝酸盐都被认为能产生抗炎条件，而普罗布考则能产生促炎条件。炎症状态的研究将通过4种不同但又相互关联的方法进行，包括：血浆细胞因子水平的估计，脾细胞对多种刺激剂的反应，白细胞中炎症相关基因的表达，以及利用免疫组织化学技术鉴定动脉粥样硬化病变中的炎症细胞和标志物。目的2：饮食中的植物类固醇和亚硝酸盐对心血管的益处可能是通过改变凝血系统来实现的。我们用上述饲料喂养这些小鼠6个月。一些凝血因子及其基因表达将被研究，并与动脉粥样硬化的程度和严重程度相关。目的3：饮食中的植物类固醇和亚硝酸盐通过全面预防冠状动脉粥样硬化来维持心脏功能和节律。我们对冠状动脉粥样硬化对心脏功能的影响的了解有限。因此，我们将用上述饲料喂养这些小鼠1年，以发展为晚期心脏病。这些小鼠将每8周接受一次超声心动图检查，以评估心脏功能。在牺牲时，将使用新的和复杂的图像分析方法来检查主动脉。

The previous NSERC Discovery Grant allowed us to learn potential synergistic effects of dietary agents and anti-rejection drugs in a rat heart transplant model. Thus, in the proposed studies we want to utilize our experiences to further enhance our knowledge of basic mechanisms of the development and prevention of transplant coronary atherosclerosis usin a genetically modified mouse model. The following 3 aims will be included in these studies:Aim 1: Cardiovascular benefits including prevention of post heart transplant complications of dietary phytosterols and nitrites are medicated through alterations in immune system. We will perform heart transplant surgeries in mice. After a full recovery from surgery, the mice will be treated with experimental diets containing phytosterols alone or with nitrite or with probucol for 12 weeks. Both dietary phytosterols and nitrite are supposed to produce anti-inflammatory conditions and probucol will produce pro-inflammatory conditions. The state of inflammation will be studied by 4 distinct but interrelated methods including, estimation of plasma cytokine levels, response of spleen cells to a number of stimulants, investigation of inflammation-related gene expression in white blood cells, and finally identification of inflammatory cells and markers in atherosclerotic lesions using immunohistochemistry techniques. Aim 2: Cardiovascular benefits of dietary phytosterols and nitrite may be mediated through alterations in the coagulation system. We will feed these mice with the above mentioned diets for 6 months. A number of coagulatory factors and their gene expression will be studied and correlated with the extent and severity of atherosclerosis. Aim 3: Dietary phytosterols and nitrite preserve cardiac function and rhythm through an overall prevention of coronary atherogenesis. Our knowledge on the impact of coronary atherosclerosis on heart function is limited. Thus we will feed these mice with above-mentioned diets for 1 year to develop advanced heart disease. The mice will undergo echocardiography procedures to evaluate heart function every 8 weeks. At sacrifice the aorta will be examined using the novel and a sophisticated image analysis method.