Estrogen and brain vascular inflammation in diabetics

糖尿病患者的雌激素和脑血管炎症

• 批准号: 6899212
• 负责人: DALE Alan PELLIGRINO
• 金额: $ 31.78万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6899212
• 关键词: cell adhesion; cerebral ischemia /hypoxia; diabetes mellitus; estrogens; glycation; hormone therapy; hyperglycemia; image processing; inflammation; intravital microscopy; laboratory rat; leukocytes; neuroprotectants; nuclear factor kappa beta; ovariectomy; progesterone; receptor; receptor expression

DESCRIPTION (provided by applicant): The neuro-and vasculoprotective properties of estrogen have been amply demonstrated in laboratory investigations. However, clinically, there are indications that hormone replacement therapy in women may not be beneficial, and even detrimental. The present project is based upon the concept that clinically-relevant circumstances may occur where estrogen replacement therapy (ERT) is no longer neuroprotective, but neurotoxic. One such circumstance is diabetes/chronic hyperglycemia (CH). Recent results showed that, whereas chronic "physiologic" ERT, in non-diabetic, ovariectomized (OVX) rats protects the brain against ischemic damage, ERT in diabetic OVX females exacerbates the damage. This project is designed to delineate the mechanisms behind this "transformation". The rationale derives from the parallel observations that CH promotes an increase in the levels of advanced glycation end-products (AGEs), while ERT promotes an increased expression of the AGE receptor, RAGE, on cerebrovascular endothelial cells. The resultant increase in RAGE activation unleashes a cascade leading to a sustained increase in the activity of the pro-inflammatory transcriptional regulator, NFkB, and a heightened potential for cerebral inflammatory activity following an ischemic insult. The 4 specific aims of this proposal are guided by the following hypotheses: 1) ERT in diabetic (streptozotocin-treated, chronically [>1 mo] hyperglycemic) OVX females will exacerbate, while ERT in non-diabetics will attenuate post-ischemic (transient forebrain ischemia) cerebrovascular inflammation, as reflected by the extent to which leukocytes adhere to pial venules. 2) Blocking RAGE, its ligands (e.g., AGE), or its downstream effector, NFkB, either via antisense or pharmacologic inhibitor treatments, will prevent the pro-adhesive action of ERT in diabetics. 3) Preventing leukocyte adhesion (via leukopenia), in addition to AGE, RAGE or NFkB blockade, will prevent ERT-associated exacerbation of ischemic brain damage. 4) Chronic progesterone (P) replacement, when combined with ERT, will prevent the pro-inflammatory and neurotoxic actions seen with ERT alone in the diabetic OVX female. Results will be evaluated based upon whether the females are intact, OVX, or OVX + 17B-estradiol (E2)-treated (or E2+P-treated), and whether the rats are diabetic or non-diabetic. The principal variables to be monitored will be post-ischemic (0-10h reperfusion) pial venular adhesion of rhodamine-6G-labeled leukocytes; neuronal cell loss (at 72h reperfusion); and expression of key proteins. The established technique being used for quantitating leukocyte adhesion involves chronic placement of closed cranial windows, intravital microscopy/videometry, and computer-assisted image processing. The results of these studies will permit us to gain an understanding of some of the mechanisms behind estrogen's conversion to the "dark side" and should lead to improvements in the clinical efficacy of hormone replacement treatments.

描述（由申请人提供）：雌激素的神经和血管保护特性已在实验室研究中得到充分证明。然而，临床上有迹象表明，激素替代疗法对女性可能没有好处，甚至有害。本项目基于这样的概念：雌激素替代疗法（ERT）不再具有神经保护作用，而是具有神经毒性，因此可能会出现临床相关情况。其中一种情况是糖尿病/慢性高血糖（CH）。最近的结果表明，虽然慢性“生理性”ERT 在非糖尿病、卵巢切除 (OVX) 大鼠中可以保护大脑免受缺血性损伤，但在糖尿病 OVX 雌性大鼠中，ERT 会加剧这种损伤。该项目旨在描绘这种“转变”背后的机制。其基本原理源自以下平行观察：CH 促进晚期糖基化终末产物 (AGE) 水平的增加，而 ERT 则促进脑血管内皮细胞上 AGE 受体 RAGE 表达的增加。由此产生的 RAGE 激活增加会释放级联反应，导致促炎转录调节因子 NFkB 的活性持续增加，并在缺血性损伤后脑部炎症活动的可能性增加。该提案的 4 个具体目标以以下假设为指导： 1) 糖尿病患者（链脲佐菌素治疗，长期 [>1 个月] 高血糖）OVX 女性中的 ERT 会加剧，而非糖尿病患者中的 ERT 会减弱缺血后（短暂性）前脑缺血）脑血管炎症，如白细胞粘附到软脑膜小静脉的程度所反映。 2) 通过反义或药物抑制剂治疗，阻断 RAGE、其配体（例如 AGE）或其下游效应子 NFkB，将阻止 ERT 在糖尿病患者中的促粘附作用。 3) 除了 AGE、RAGE 或 NFkB 阻断之外，防止白细胞粘附（通过白细胞减少）将防止 ERT 相关的缺血性脑损伤恶化。 4) 慢性黄体酮 (P) 替代与 ERT 联合使用，可防止单独使用 ERT 时在患有糖尿病 OVX 的女性中出现的促炎和神经毒性作用。将根据雌性是否完整、OVX 或 OVX + 17B-雌二醇 (E2) 治疗（或 E2+P 治疗）以及大鼠是否患有糖尿病或非糖尿病来评估结果。监测的主要变量是缺血后（再灌注0-10小时）软脑膜静脉粘连罗丹明6G标记的白细胞；神经元细胞损失（再灌注 72 小时）；以及关键蛋白的表达。用于定量白细胞粘附的既定技术涉及封闭颅窗的长期放置、活体显微镜/视频测量和计算机辅助图像处理。这些研究的结果将使我们能够了解雌激素转化为“阴暗面”背后的一些机制，并应能改善激素替代治疗的临床疗效。