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，在临床上，有迹象表明激素替代疗法对女性可能没有好处，甚至是有害的。本项目是基于这样一个概念，即在临床相关的情况下，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。其中一种情况是糖尿病/慢性高血糖(CH)。最近的结果表明，在非糖尿病卵巢切除(OVX)大鼠中，慢性“生理性”ERT保护大脑免受缺血损伤，而糖尿病OVX雌性大鼠的ERT则加剧了这种损伤。这个项目旨在勾勒出这一“转变”背后的机制。其基本原理来自于平行的观察，即CH促进晚期糖基化终产物(AGEs)水平的增加，而ERT促进脑血管内皮细胞上AGE受体RAGE的表达增加。由此导致的RAGE激活的增加释放了一个级联反应，导致促炎转录调节因子NFkB的活性持续增加，并增加了脑缺血损伤后脑部炎症活动的可能性。这项建议的4个具体目标是由以下假设指导的：1)糖尿病(链脲佐菌素治疗，慢性高血糖)OVX女性的ERT将加剧，而非糖尿病患者的ERT将减轻缺血后(短暂性前脑缺血)脑血管炎症，这反映在白细胞与软脑膜小静脉的粘连程度上。2)阻断RAGE、其配体(如AGE)或其下游效应因子NFkB，无论是通过反义或药物抑制剂治疗，都将阻止ERT在糖尿病患者中的促黏附作用。3)防止白细胞黏附(通过白细胞减少)，加上年龄、RAGE或NFkB阻断，将防止ERT相关的缺血性脑损伤的加重。4)当慢性黄体酮(P)替代疗法与ERT联合使用时，将阻止在糖尿病OVX女性患者中单独使用ERT的促炎和神经毒性作用。结果将根据雌性是否完整、OVX或OVX+17B-雌二醇(E_2)治疗(或E_2+P治疗)以及大鼠是否患有糖尿病进行评估。需要监测的主要变量将是缺血后(0-10h再灌流)罗丹明-6G标记的白细胞的软膜静脉粘连；神经细胞丢失(再灌流72h)；以及关键蛋白的表达。已建立的用于定量白细胞黏附的技术包括慢性放置关闭的颅窗、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黑暗面背后的一些机制，并应导致激素替代治疗的临床疗效的改善。