Forms of Vitamin E Have Opposing Effects on Inflammation

说明(申请人提供)：在欧洲几个国家(芬兰和意大利)的研究中，维生素E已被建议发挥抗炎作用，并已被证明在小鼠实验性哮喘和哮喘患者中有效地减少炎症。令人失望的是，维生素E在美国的试验并未显示出对哮喘的益处。我们最近发现了维生素E异构体(生育酚和生育酚)未知的特性，这可能解释了临床研究中这些令人惊讶的不同结果。生育酚和生育酚是美国人消费的两种主要形式的维生素E。我们已经证明了？？-生育酚可以增加炎症。此外，β-生育酚在组织中的浓度仅为组织浓度的10%时，就能消除β-生育酚在小鼠实验性哮喘中的抗炎作用，并在体外消除白细胞迁移的作用。此外，这些生育酚在白细胞迁移过程中对内皮细胞有直接影响。由于？-生育酚在美国人的饮食中含量很高，但在大多数欧洲人的饮食中不存在，这种生育酚异构体拮抗作用可能具有重要的临床意义。一些报告表明，美国人血浆中的生育酚水平是欧洲人的2-5倍。此外，研究表明，在动物模型中，β-生育酚在炎症过程中的益处与动物饮食中非常低的生育酚水平是一致的。在开始人类研究之前，了解这两种主要形式的维生素E相反调节炎症的分子机制是非常重要的。本建议中描述的实验的目的是检验关于生育酚抗炎作用的机制以及生育酚对这些作用的拮抗作用的假说。我们将使用纯化的天然生育酚和体外和体内相结合的方法，在小鼠和培养细胞中建立良好的模型系统。我们研究的信息将对临床研究的设计和美国人的维生素E消费产生重大影响。假设：维生素E是生育酚和生育三烯醇的复杂混合物，其抗炎作用因生育酚的不同形式而异。天然d-生育酚通过清除ROS和抑制PKC，直接作用于血管内皮细胞，从而抑制白细胞转运信号。相比之下，天然的d-生育酚与生育酚的益处相竞争，并通过在炎症过程中提升内皮功能而表现出非抗氧化性的促炎作用。具体目的：目的1.我们将确定在实验性哮喘中，利用？-生育酚进行的？-生育酚消融是否可逆。目的2.我们将通过调节内皮细胞黏附分子VCAM-1激活的信号来确定？-生育酚是否阻断和？-生育酚增加白细胞的迁移。目的3.我们将通过调节内皮细胞黏附分子ICAM-1激活的信号来确定？-生育酚是否阻断和？-生育酚增加白细胞的迁移。 公共卫生相关性：我们对维生素E形式的研究揭示了维生素E形式对哮喘的新的相反作用。我们关于维生素E的数据表明，在动物和人类的研究中，以及在美国人和欧洲人的研究中，维生素E结果不同的一个来源是，维生素E的？-生育酚形式对抗维生素E的？-生育酚形式的作用。此外，与欧洲国家相比，美国人饮食中的？-生育酚形式较高，美国人的血浆中也较高。这项建议使用体内和体外模型解决了生育酚和生育酚对抗炎症作用的机制。我们研究的机理数据将有助于在未来的临床研究中确定各种形式的维生素E的改良消费量。

DESCRIPTION (provided by applicant): Vitamin E has been suggested to exert anti-inflammatory actions and has been shown to be effective in reducing inflammation in experimental asthma in mice and in asthmatics in studies in several countries in Europe (Finland and Italy). Disappointingly, vitamin E trials in the United States have failed to show benefit in asthma. We have recently discovered unrecognized properties of vitamin E isoforms (?-tocopherol and ?-tocopherol) that may explain these surprisingly disparate results in the clinical studies. ?-tocopherol and ?-tocopherol are the two major forms of vitamin E that are consumed by Americans. We have demonstrated that ??-tocopherol elevates inflammation. Moreover, ?-tocopherol, at as little as 10% the tissue concentration of ?- tocopherol, ablated the anti-inflammatory benefit of ?-tocopherol in experimental asthma in mice and in vitro in leukocyte migration. Furthermore, these tocopherols had direct effects on the endothelium during leukocyte migration. Since ?-tocopherol is found at high levels in the American diet, but not in most diets of Europeans, this tocopherol isoform antagonism could be of significant clinical relevance. Several reports indicate that plasma levels of ?-tocopherol in Americans are 2-5 times higher than Europeans. Furthermore, the studies that demonstrate a benefit of ?-tocopherol during inflammation in animal models are consistent with the very low levels of ?-tocopherol in animal diets. Before initiating human studies, it is very important to understand the molecular mechanisms for the opposing modulation of inflammation by these two major forms of vitamin E. The goal of the experiments described in this proposal is to test hypotheses regarding the mechanism of the anti-inflammatory effects of ?-tocopherol and the antagonism of these effects by ?-tocopherol. We will use purified natural ?- and ?-tocopherols and a combined in vitro and in vivo approach with well-developed model systems in mice and cultured cells. Information from our studies will have significant impact on the design of clinical studies and on vitamin E consumption by Americans. Hypothesis: Vitamin E, a complex mixture of tocopherols and tocotrienols, elicits anti-inflammatory effects that vary among the forms of tocopherols. Natural d-??-tocopherol inhibits signals for leukocyte trafficking by direct effects on endothelium via scavenging ROS and inhibiting PKC??. In contrast, natural d-??- tocopherol competes against the benefit of ?-tocopherol and exhibits non-antioxidant proinflammatory effects by elevating endothelial function during inflammation. Specific Aims: Aim 1. We shall determine whether the ?-tocopherol ablation of the benefit of ?- tocopherol is reversible in experimental asthma. AIM 2. We shall determine whether ?-tocopherol blocks and ?- tocopherol elevates leukocyte migration by modulating signals activated by the endothelial cell adhesion molecule VCAM-1. AIM 3. We shall determine whether ?-tocopherol blocks and ?-tocopherol elevates leukocyte migration by modulating signals activated by the endothelial cell adhesion molecule ICAM-1. PUBLIC HEALTH RELEVANCE: Our studies on forms of vitamin E reveal novel opposing effects of forms of vitamin E on asthma. Our data with vitamin E suggest that a source for the disparate results in vitamin E outcomes in studies with animals versus humans and in studies with Americans versus Europeans is that the ?-tocopherol form of vitamin E antagonizes the action of the ?-tocopherol form of vitamin E. Furthermore, the ?-tocopherol form is high in the American diet and is high in plasma in the United States as compared to European countries. This proposal addresses mechanisms for opposing effects of ?-tocopherol and ?-tocopherol on inflammation using in vivo and in vitro models. The mechanistic data from our studies will help define modified consumption of forms of vitamin E in future clinical studies.