Establishing basic biological mechanisms governing cardiovascular benefits

先前的NSERC发现基金允许我们在大鼠心脏移植模型中了解膳食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进一步提高我们对转基因小鼠模型中移植性冠状动脉粥样硬化发生和预防的基本机制的认识。以下三个目标将包括在这些研究中：目标1：心血管益处，包括预防心脏移植后并发症的膳食植物甾醇和亚硝酸盐是通过改变免疫系统进行治疗的。我们将在老鼠身上进行心脏移植手术。手术完全恢复后，小鼠将被单独喂食含有植物甾醇或亚硝酸盐或普罗布考的实验性饮食，为期12周。膳食中的植物甾醇和亚硝酸盐都能产生抗炎作用，而普罗布考则会产生促炎作用。炎症状态将通过4种不同但相互关联的方法进行研究，包括血浆细胞因子水平的估计，脾脏细胞对多种兴奋剂的反应，白细胞中炎症相关基因表达的研究，以及最后使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：膳食植物甾醇和亚硝酸盐对心血管的益处可能是通过改变凝血系统介导的。我们将用上述饮食喂养这些小鼠6个月。许多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：膳食植物甾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心律。我们对冠状动脉粥样硬化对心功能影响的了解有限。因此，我们将用上述饮食喂养这些小鼠1年，使其发展为晚期心脏病。每8周进行一次超声心动图检查，评估小鼠的心脏功能。在牺牲主动脉将检查使用新颖和复杂的图像分析方法。

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.