Role of the kallikrein-kinin system in diabetic retinopathy

描述（由申请人提供）：糖尿病视网膜病变是发达国家视力丧失的主要原因。糖尿病视网膜病变进展到危及视力阶段，包括糖尿病黄斑水肿（DME），通常与潜在视网膜血管功能障碍和疾病的恶化有关，包括视网膜出血数量和严重程度的增加。最近的临床进展表明，玻璃体内注射抗vegf定向治疗在改善DME患者的视力和解决黄斑水肿方面是有效的，FDA最近批准了玻璃体内注射雷尼单抗治疗DME。虽然这种治疗对许多DME患者非常有效，但几项大型临床研究表明，大约40 - 50%的研究对象出现屈光现象，或者对抗vegf定向治疗的视力改善和视网膜增厚的解决没有完全反应。这些临床发现表明，vegf不依赖的机制也可能导致大量DME患者的视网膜水肿。在最近的报道和额外的初步数据中，我们发现血浆钾激肽肽（Pkal）、FXII因子和激肽原在DME患者的玻璃体中升高。我们还发现玻璃体中的Pkal水平与VEGF水平无关，揭示了DME患者分子异质性的一个组成部分。通过基因敲除和药理学方法，我们发现Pkal有助于啮齿动物的视网膜血管通透性高和视网膜增厚，我们已经开始描述缓激肽依赖和独立的机制，这些机制有助于这种反应。我们的研究发现糖尿病增加了Pkal对血管功能障碍和视网膜水肿的作用（Clermont et al diabetes 2011; Liu et al Nature Medicine 2011）。我们最近也表明，引入玻璃体的自体血液会增加视网膜炎症和视网膜血管通透性（Liu et al IOVS 2013），在诱导视网膜增厚方面，钾激肽素系统与VEGF一样有效。此外，我们已经使用蛋白质组学来表征缓激肽诱导的视网膜水肿，并确定了一组血浆蛋白，这些蛋白在视网膜水肿中显著增加，同时视网膜中间细丝蛋白亚群显著减少。该基金将确定PK诱导的导致视网膜血管高通透性和视网膜增厚的机制，并检验pkal -缓激素系统是导致二甲醚的视网膜功能障碍的vegf独立介质的假设。具体目的是1)表征和比较Pkal对糖尿病小鼠视网膜水肿的缓激肽受体依赖和独立作用；2)比较Pkal和vegf诱导的视网膜水肿并研究这些途径之间的相互作用；3)表征一氧化氮合酶和calpain介导的中间纤维降解/重塑在视网膜水肿中的作用。进一步确定血浆钾激肽系统在视网膜中的作用机制和调控将有助于

DESCRIPTION (provided by applicant): Diabetic retinopathy is a leading cause of vision loss in developed countries. Progression to sight threatening stages of diabetic retinopathy, including diabetic macular edema (DME), is usually associated with worsening of underlying retinal vascular dysfunction and disease, including an increase in the number and severity of retinal hemorrhages. Recent clinical advances have demonstrated that intravitreal injection of anti-VEGF directed therapies are effective in improving visual acuity and resolving macular edema in DME, and the FDA has recently approved intravitreal injection of ranibizumab for DME. While this treatment is highly effective for many patients with DME, several large clinical studies have revealed that about 40 to 50% of study subjects appear refractive or do not fully respond in the improvement of visual acuity and the resolution of retinal thickening to anti-VEGF directed therapies. These clinical findings suggest that VEGF-independent mechanisms might also contribute to retinal edema in a large number of DME patients. In recent reports and additional preliminary data, we show that plasma kallikrein (Pkal), factor FXII, and kininogen are increased in the vitreous of patients with DME. We also show that Pkal levels in the vitreous do not correlate with VEGF levels, revealing a component of molecular heterogeneity among DME patients. Using both knockout and pharmacological approaches, we show that Pkal contributes to retinal vascular hyperpermeability and retinal thickening in rodents and we have begun to characterize both bradykinin-dependent and -independent mechanisms that contribute to this response. Our studies have revealed that diabetes increases the effects of Pkal on vascular dysfunction and retinal edema (Clermont et al Diabetes 2011, Liu et al Nature Medicine 2011). We have also recently shown that autologous blood introduced into the vitreous increases retinal inflammation and retinal vascular permeability (Liu et al IOVS 2013) and the kallikrein system is as potent as VEGF in inducing retinal thickening. In addition we have used proteomics to characterize bradykinin-induced retinal edema and have identified a set of plasma proteins that are robustly increased in retinal edema coupled with striking decreases in a subset of retinal intermediate filament proteins. This grant will identify the PK- induced mechanisms that cause retinal vascular hyperpermeability and retinal thickening, and examine the hypothesis that the Pkal-bradykinin system is a VEGF-independent mediator of retinal dysfunction that contributes to DME. The specific aims are 1) to characterize and compare the bradykinin receptor-dependent and independent effects of Pkal on retinal edema in diabetic mice, 2) to compare Pkal and VEGF-induced retinal edema and investigate interactions between these pathways, and 3) characterize the roles of nitric oxide synthase and calpain-mediated intermediate filament degradation/remodeling in retina edema. Further identification of the mechanism of action and regulation of the plasma kallikrein system in the retina will be helpful in evaluating potential clinical opportunities for targeting the Pkal system for the treatment of DME.