Loukovaara Sirpa, Sandholm Jouko, Aalto Kristiina, Liukkonen Janne, Jalkanen Sirpa, Yegutkin Gennady G
Unit of Vitreoretinal Surgery, Department of Ophthalmology, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland.
Cell Imaging Core, Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland.
J Mol Med (Berl). 2017 Feb;95(2):193-204. doi: 10.1007/s00109-016-1472-6. Epub 2016 Sep 16.
Clear signaling roles for ATP and adenosine have been established in all tissues, including the eye. The magnitude of signaling responses is governed by networks of enzymes; however, little is known about the regulatory mechanisms of purinergic signaling in the eye. By employing thin-layer chromatographic assays with H-labeled substrates, this study aimed to evaluate the role of nucleotide homeostasis in the pathogenesis of vitreoretinal diseases in humans. We have identified soluble enzymes ecto-5'-nucleotidase/CD73, adenylate kinase-1, and nucleoside diphosphate kinase in the vitreous fluid that control active cycling between pro-inflammatory ATP and anti-inflammatory adenosine. Strikingly, patients with proliferative form of diabetic retinopathy (DR) had higher adenylate kinase activity and ATP concentration, when compared to non-proliferative DR eyes and non-diabetic controls operated for rhegmatogenous retinal detachment, macular hole, and pucker. The non-parametric correlation analysis revealed positive correlations between intravitreal adenylate kinase and concentrations of ATP, ADP, and other angiogenic (angiopoietins-1 and -2), profibrotic (transforming growth factor-β1), and proteolytic (matrix metalloproteinase-9) factors but not erythropoietin and VEGF. Immunohistochemical staining of postmortem human retina additionally revealed selective expression of ecto-5'-nucleotidase/CD73 on the rod-and-cone-containing photoreceptor cells. Collectively, these findings provide novel insights into the regulatory mechanisms that influence purinergic signaling in diseased eye and open up new possibilities in the development of enzyme-targeted therapeutic approaches for prevention and treatment of DR.
Ecto-5'-nucleotidase/CD73 and adenylate kinase-1 circulate in human vitreous fluid. Adenylate kinase activity is high in diabetic eyes with proliferative retinopathy. Diabetic eyes display higher intravitreal ATP/ADP ratio than non-diabetic controls. Soluble adenylate kinase maintains resynthesis of inflammatory ATP in diabetic eyes.
ATP和腺苷在包括眼睛在内的所有组织中都已确立了明确的信号传导作用。信号反应的强度由酶网络控制；然而，关于眼睛中嘌呤能信号传导的调节机制知之甚少。通过使用带有H标记底物的薄层色谱分析，本研究旨在评估核苷酸稳态在人类玻璃体视网膜疾病发病机制中的作用。我们在玻璃体液中鉴定出了可溶性酶ecto-5'-核苷酸酶/CD73、腺苷酸激酶-1和核苷二磷酸激酶，它们控制促炎ATP和抗炎腺苷之间的活性循环。令人惊讶的是，与接受孔源性视网膜脱离、黄斑裂孔和视网膜前膜手术的非增殖性糖尿病视网膜病变（DR）眼和非糖尿病对照相比，增殖性糖尿病视网膜病变（DR）患者的腺苷酸激酶活性和ATP浓度更高。非参数相关分析显示玻璃体内腺苷酸激酶与ATP、ADP以及其他血管生成（血管生成素-1和-2）、促纤维化（转化生长因子-β1）和蛋白水解（基质金属蛋白酶-9）因子的浓度之间呈正相关，但与促红细胞生成素和VEGF无关。对死后人类视网膜的免疫组织化学染色进一步显示ecto-5'-核苷酸酶/CD73在含有视杆和视锥的光感受器细胞上有选择性表达。总的来说，这些发现为影响患病眼睛中嘌呤能信号传导的调节机制提供了新的见解，并为开发针对酶的预防和治疗DR的治疗方法开辟了新的可能性。
ecto-5'-核苷酸酶/CD73和腺苷酸激酶-1在人玻璃体液中循环。增殖性视网膜病变的糖尿病眼中腺苷酸激酶活性高。糖尿病眼的玻璃体内ATP/ADP比值高于非糖尿病对照。可溶性腺苷酸激酶维持糖尿病眼中炎性ATP的再合成。
