吲哚胺 2,3-双加氧酶缺失抑制糖尿病小鼠视网膜血管退化。
The Absence of Indoleamine 2,3-Dioxygenase Inhibits Retinal Capillary Degeneration in Diabetic Mice.
机构信息
Departments of Ophthalmology and Visual Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States.
Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado, United States.
出版信息
Invest Ophthalmol Vis Sci. 2018 Apr 1;59(5):2042-2053. doi: 10.1167/iovs.17-22702.
PURPOSE
Loss of retinal capillary endothelial cells and pericytes through apoptosis is an early event in diabetic retinopathy (DR). Inflammatory pathways play a role in early DR, yet the biochemical mechanisms are poorly understood. In this study, we investigated the role of indoleamine 2,3-dioxygenase (IDO), an inflammatory cytokine-inducible enzyme, on retinal endothelial apoptosis and capillary degeneration in the diabetic retina.
METHODS
IDO was detected in human and mouse retinas by immunohistochemistry or Western blotting. Interferon-γ (IFN-γ) levels were measured by ELISA. IDO levels were measured in human retinal capillary endothelial cells (HREC) cultured in the presence of IFN-γ ± 25 mM D-glucose. Reactive oxygen species (ROS) were measured using CM-H2DCFDA dye and apoptosis was measured by cleaved caspase-3. The role of IDO in DR was determined in IDO knockout (IDO-/-) mice with streptozotocin-induced diabetes.
RESULTS
The IDO and IFN-γ levels were higher in human diabetic retinas with retinopathy relative to nondiabetic retinas. Immunohistochemical data showed that IDO is present in capillary endothelial cells. IFN-γ upregulated the IDO and ROS levels in HREC. The blockade of either IDO or kynurenine monooxygenase led to inhibition of ROS in HREC. Apoptosis through this pathway was inhibited by an ROS scavenger, TEMPOL. Capillary degeneration was significantly reduced in diabetic IDO-/- mice compared to diabetic wild-type mice.
CONCLUSIONS
The results suggest that the kynurenine pathway plays an important role in the inflammatory damage in the diabetic retina and could be a new therapeutic target for the treatment of DR.
目的
视网膜毛细血管内皮细胞和周细胞通过细胞凋亡丢失是糖尿病视网膜病变（DR）的早期事件。炎症途径在早期 DR 中起作用，但生化机制知之甚少。在这项研究中，我们研究了吲哚胺 2,3-双加氧酶（IDO）在糖尿病视网膜中对视网膜内皮细胞凋亡和毛细血管退化的作用，IDO 是一种炎症细胞因子诱导的酶。
方法
通过免疫组织化学或 Western blot 检测人眼和鼠眼的 IDO。通过 ELISA 测量干扰素-γ（IFN-γ）水平。在存在 IFN-γ±25mM D-葡萄糖的情况下，测量人视网膜毛细血管内皮细胞（HREC）中 IDO 的水平。使用 CM-H2DCFDA 染料测量活性氧（ROS），并用切割的 caspase-3 测量细胞凋亡。通过链脲佐菌素诱导的糖尿病 IDO 敲除（IDO-/-）小鼠来确定 IDO 在 DR 中的作用。
结果
与非糖尿病视网膜相比，伴有视网膜病变的人糖尿病视网膜中的 IDO 和 IFN-γ 水平更高。免疫组织化学数据表明 IDO 存在于毛细血管内皮细胞中。IFN-γ 上调 HREC 中的 IDO 和 ROS 水平。IDO 或犬尿氨酸单加氧酶的阻断导致 HREC 中的 ROS 抑制。通过这种途径的凋亡被 ROS 清除剂 TEMPOL 抑制。与糖尿病野生型小鼠相比，糖尿病 IDO-/-小鼠的毛细血管退化明显减少。
结论
结果表明，犬尿氨酸途径在糖尿病视网膜的炎症损伤中起重要作用，可能成为治疗 DR 的新治疗靶点。
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