The retinal microenvironment in diabetic retinopathy

糖尿病视网膜病变的视网膜微环境

• 批准号: 8316113
• 负责人: ROBERT A. LINSENMEIER
• 金额: $ 36.75万
• 依托单位: NORTHWESTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8316113
• 关键词: Acidosis; Acute; Adult; Affect; Age; Animals; Blood Vessels; Blood capillaries; Blood flow; Carbonic Acid; Clinical; Complications of Diabetes Mellitus; Diabetes Mellitus; Diabetic Retinopathy; Disease; Disease Progression; Dropout; Endothelial Cells; Environmental Risk Factor; Event; Excision; Experimental Diabetes Mellitus; Extravasation; Felis catus; Functional disorder; Hyperglycemia; Hypoxia; Lead; Letters; Link; Long-Evans Rats; Measurement; Measures; Messenger RNA; Metabolism; Michigan; Microspheres; Molecular; Neonatal; Oxygen; Pathway interactions; Phase; Play; Proteins; Rattus; Regulation; Relative (related person); Retina; Retinal; Retinal Diseases; Rodent; Role; Signal Transduction; Streptozocin; Testing; Time; Tissues; Treatment Protocols; Tumor Tissue; Vascular Endothelial Growth Factors; Work; angiogenesis; capillary; carbonate dehydratase; diabetic; insight; insulin signaling; relating to nervous system; response; transcription factor; type I and type II diabetes

DESCRIPTION (provided by applicant): Diabetic retinopathy is one of the most common causes of retinal disease in adults. Many molecular and histological changes have been demonstrated, and it is now recognized that neural as well as vascular problems exist. The most important contributor to vascular dysfunction is the elevation of vascular endothelial growth factor (VEGF), which causes vascular leakage and angiogenesis. Unfortunately, we still do not know what underlies the increase in VEGF. Hypoxia and acidosis are both known regulators of VEGF, but the magnitude and time course of changes in retinal oxygen and pH are not known in diabetes. More information about these parameters will allow a better understanding of disease progression, and ultimately may lead to an understanding of pathways that can be targeted before VEGF causes damage. We will make intraretinal recordings of PO2 and pH in rats with streptozotocin (STZ)-induced diabetes, and in rats with acidosis in the absence of diabetes. To place these changes in the context of other events, we will also measure important vascular parameters (blood flow, leakage, molecular signals). SPECIFIC AIM 1: Oxygen in diabetic retinopathy. Retinal tissue hypoxia has been implicated in the increased VEGF that is found in both the background and proliferative phases of retinopathy. There is considerable indirect support for the existence of hypoxia in diabetic retinopathy, but very limited direct evidence. We will characterize intraretinal oxygenation in rats with up to 1 year of diabetes. Our hypothesis is that inner retinal PO2 will decrease over this time. We will also investigate changes in the regulation of retinal oxygen in diabetics. Our hypothesis is that changes in regulation of PO2 will be a more sensitive indicator of changes in the microenvironment and occur earlier than changes in baseline PO2. We found increased PO2 in the retina in an earlier study at 12 weeks of diabetes. Our hypothesis is that this was due to increased blood flow, which we will now investigate. SPECIFIC AIM 2: Acidosis in diabetic retinopathy. VEGF is regulated by acidosis in some tissues but the role of pH in controlling VEGF in the adult retina is unknown. We will characterize retinal pH in rats with up to 1 year of diabetes. Our hypothesis is that the inner retina will be more acidic than normal for at least a few months. We also hypothesize that molecular mechanisms come into play to reduce acidosis, such as increased carbonic anhydrase and acid removal mechanisms. These will be evaluated with mRNA and protein measurements. SPECIFIC AIM 3: Is retinal acidosis sufficient to upregulate VEGF? Finding that the diabetic retina is acidotic will open the possibility that it is one of the factors that regulates VEGF, but will not tell us whether it is important. Consequently, we will produce acidosis in the absence of diabetes, via carbonic anhydrase inhibition. We will first establish a treatment protocol that yields intraretinal pH values similar to diabetes, and then evaluate changes in VEGF and leakage. Our hypothesis is that acidosis alone will be sufficient to increase VEGF, produce molecular changes that underlie leakage, and cause leakage itself.

描述（由申请人提供）：糖尿病视网膜病变是成人视网膜疾病的最常见原因之一。许多分子和组织学变化已得到证实，现在人们认识到存在神经和血管问题。血管功能障碍的最重要因素是血管内皮生长因子（VEGF）的升高，这会导致血管渗漏和血管生成。不幸的是，我们仍然不知道 VEGF 增加的原因是什么。缺氧和酸中毒都是已知的 VEGF 调节因子，但糖尿病中视网膜氧和 pH 值变化的幅度和时间过程尚不清楚。有关这些参数的更多信息将有助于更好地了解疾病进展，并最终可能导致了解 VEGF 造成损害之前可靶向的途径。我们将在链脲佐菌素 (STZ) 诱导的糖尿病大鼠和无糖尿病的酸中毒大鼠中进行 PO2 和 pH 的视网膜内记录。为了将这些变化置于其他事件的背景下，我们还将测量重要的血管参数（血流量、渗漏、分子信号）。具体目标 1：糖尿病视网膜病变中的氧气。视网膜组织缺氧与 VEGF 增加有关，这种增加出现在视网膜病变的背景期和增殖期。有相当多的间接支持糖尿病视网膜病变中存在缺氧，但直接证据非常有限。我们将描述患有糖尿病长达 1 年的大鼠的视网膜内氧合特征。我们的假设是，视网膜内 PO2 在此期间会下降。我们还将研究糖尿病患者视网膜氧调节的变化。我们的假设是，PO2 调节的变化将是微环境变化的更敏感指标，并且比基线 PO2 的变化更早发生。在一项早期研究中，我们发现糖尿病 12 周时视网膜中的 PO2 增加。我们的假设是，这是由于血流量增加所致，我们现在将对此进行研究。具体目标 2：糖尿病视网膜病变中的酸中毒。 VEGF 在某些组织中受到酸中毒的调节，但 pH 在控制成人视网膜中 VEGF 中的作用尚不清楚。我们将描述患有糖尿病长达 1 年的大鼠的视网膜 pH 值。我们的假设是，内部视网膜至少在几个月内会比正常情况更酸性。我们还假设分子机制在减少酸中毒方面发挥作用，例如增加碳酸酐酶和除酸机制。这些将通过 mRNA 和蛋白质测量进行评估。具体目标 3：视网膜酸中毒是否足以上调 VEGF？发现糖尿病视网膜酸中毒将开启它是调节 VEGF 的因素之一的可能性，但不会告诉我们它是否重要。因此，在没有糖尿病的情况下，我们会通过碳酸酐酶抑制产生酸中毒。我们将首先建立一个治疗方案，产生与糖尿病相似的视网膜内 pH 值，然后评估 VEGF 和渗漏的变化。我们的假设是，仅酸中毒就足以增加 VEGF，产生导致渗漏的分子变化，并导致渗漏本身。