Hypercholesterolemia and Human Skin Blood Flow

描述（由申请人提供）：皮肤循环是一种可接近的、代表性的血管床，用于体内检查导致血管功能障碍的机制。该提议是我们之前研究皮肤血流控制中与年龄相关的变化的神经血管机制的工作的逻辑延伸。拟议的研究扩展了我们之前的研究，以检查高胆固醇血症 (HC) 人群的皮肤血管舒张 (VD) 信号传导机制。 HC 导致的 VD 信号传导受损的特点是氧化应激增加以及内皮一氧化氮 (NO) 的损失；这些事件共同导致与动脉粥样硬化发病机制相关的内皮功能障碍。介导内皮NO减少的确切机制仍不清楚。 HC 可能减少 NO 的假定位点包括 1) 氧化低密度脂蛋白 (ox-LDL) 诱导的血管精氨酸酶活性上调，其优先将常见的 NO 合酶 (NOS) 底物 L-精氨酸 (L-arg) 代谢为 L-鸟氨酸和尿素，以及 2) 内皮 (e)NOS 解偶联，其中 eNOS 通过产生超氧化物而有助于增加氧化应激由于底物 (L-arg) 或必需辅因子（四氢生物蝶呤）缺乏。此外，ox-LDL诱导的血管精氨酸酶活性增强与动脉粥样硬化的发病机制之间存在机制联系，通过增加多胺和脯氨酸前体L-鸟氨酸，从而导致内膜增厚。为此，拟议的研究将使用最先进的体内皮肤特定技术（局部加热和皮内微透析）结合皮肤活检的经典体外生化分析，系统地探索HC影响NO依赖性皮肤VD受损的机制。具体目标 1 和 2 将分别从机制上检查精氨酸酶和氧化应激在 eNOS 解偶联情况下的作用，以阐明与年龄匹配的正常胆固醇对照组相比，它们对 HC 组 VD 功能障碍的贡献。具体目标 3 将通过 eNOS 和精氨酸酶基因表达、酶活性和蛋白质浓度的体外生化分析来补充目标 1 和 2。具体目标 4 检查了目标 1-3 中在使用阿托伐他汀进行他汀类药物治疗干预之前和之后研究的机制。

DESCRIPTION (provided by applicant): The cutaneous circulation is an accessible, representative vascular bed for in vivo examination of mechanisms that contribute to vascular dysfunction. This proposal is a logical extension of our previous work investigating the neurovascular mechanisms underlying age-related changes in the control of skin blood flow. The proposed studies expand our previous research to examine cutaneous vasodilatory (VD) signaling mechanisms in a hypercholesterolemic (HC) population. Impaired VD signaling with HC is characterized by an increase in oxidant stress coupled with the loss of endothelial nitric oxide (NO); together these events contribute to endothelial dysfunction associated with the pathogenesis of atherosclerosis. The precise mechanisms mediating decreased endothelial NO remain unclear. Putative sites through which NO may be decreased with HC include 1) oxidized low density lipoprotein (ox-LDL)-induced upregulation of vascular arginase activity, which preferentially metabolizes the common NO-synthase (NOS) substrate L- arginine (L-arg) to L-ornithine and urea and 2) endothelial (e)NOS uncoupling where eNOS contributes to increased oxidant stress by producing superoxide as a result of substrate (L-arg) or essential cofactor (tetrahydrobiopterin) deficiency. Additionally, there is a mechanistic link between ox-LDL-induced augmented vascular arginase activity and the pathogenesis of atherosclerosis through an increase in the polyamine and proline precursor L-ornithine which contributes to intimal thickening. To this end, the proposed investigations will systematically explore mechanisms affecting impaired NO- dependent cutaneous VD with HC using state-of-the-art in vivo skin specific techniques (local heating and intradermal microdialysis) paired with classic in vitro biochemical analysis of cutaneous biopsies. Specific Aims 1 and 2 will mechanistically examine the roles of arginase, and oxidant stress in the context of eNOS uncoupling, respectively, to clarify their contributions to VD dysfunction with HC compared to an age- matched normocholesterolemic control group. Specific Aim 3 will complement Aims 1 and 2 with in vitro biochemical analysis of eNOS and arginase gene expression, enzyme activity, and protein concentration. Specific Aim 4 examines the mechanisms investigated in Aims 1-3 before and after a statin therapy intervention with atrovastatin.