Department of Ophthalmology, Georgia Regents University, 30909, USA.
Life Sci. 2013 Jul 30;93(2-3):78-88. doi: 10.1016/j.lfs.2013.05.024. Epub 2013 Jun 12.
This study was undertaken to determine the effect of an adenosine kinase inhibitor (AKI) in diabetic retinopathy (DR). We have shown previously that adenosine signaling via A2A receptors (A2AAR) is involved in retinal protection from diabetes-induced inflammation. Here we demonstrate that AKI-enhanced adenosine signaling provides protection from DR in mice.
We targeted AK, the key enzyme in adenosine metabolism, using a treatment regime with the selective AKI, ABT-702 (1.5mg/kg intraperitoneally twice a week) commencing at the beginning of streptozotocin-induced diabetes at the age of eight weeks. This treatment, previously demonstrated to increase free adenosine levels in vivo, was maintained until the age of 16 weeks. Retinal inflammation was evaluated using Western blot, Real-Time PCR and immuno-staining analyses. Role of A2AAR signaling in the anti-inflammation effect of ABT-702 was analyzed in Amadori-glycated-albumin (AGA)-treated microglial cells.
At 16 weeks, when diabetic mice exhibit significant signs of retinal inflammation including up-regulation of oxidative/nitrosative stress, A2AAR, ENT1, Iba1, TNF-α, ICAM1, retinal cell death, and down-regulation of AK, the ABT-702 treated group showed lower signs of inflammation compared to control animals receiving the vehicle. The involvement of adenosine signaling in the anti-inflammation effect of ABT-702 was supported by the TNF-α release blocking effect of A2AAR antagonist in AGA-treated microglial cells.
These results suggest a role for AK in regulating adenosine receptor signaling in the retina. Inhibition of AK potentially amplifies the therapeutic effects of site- and event-specific accumulation of extracellular adenosine, which is of highly translational impact.
本研究旨在确定腺嘌呤激酶抑制剂（AKI）在糖尿病视网膜病变（DR）中的作用。我们之前已经表明，通过 A2A 受体（A2AAR）的腺苷信号参与了从糖尿病引起的炎症中保护视网膜。在这里，我们证明 AKI 增强的腺苷信号为小鼠提供了对 DR 的保护。
我们使用选择性 AKI，ABT-702（每周两次腹腔内 1.5mg/kg）的治疗方案靶向 AK，AK 是腺苷代谢的关键酶，该治疗方案从 8 周龄的链脲佐菌素诱导的糖尿病开始，并持续到 16 周龄。该治疗方案以前被证明可以增加体内游离腺苷水平。使用 Western blot、实时 PCR 和免疫染色分析评估视网膜炎症。在 Amadori 糖化白蛋白（AGA）处理的小胶质细胞中分析 A2AAR 信号在 ABT-702 抗炎作用中的作用。
在 16 周时，当糖尿病小鼠表现出明显的视网膜炎症迹象，包括氧化/硝化应激、A2AAR、ENT1、Iba1、TNF-α、ICAM1、视网膜细胞死亡的上调，以及 AK 的下调时，与接受载体的对照动物相比，接受 ABT-702 治疗的组显示出较低的炎症迹象。ABT-702 在 AGA 处理的小胶质细胞中阻断 TNF-α 释放的作用支持了腺苷信号在 ABT-702 抗炎作用中的参与。
这些结果表明 AK 在调节视网膜中腺苷受体信号方面的作用。AK 的抑制可能会增强细胞外腺苷的位点和事件特异性积累的治疗效果，这具有高度的转化意义。
