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Invest Ophthalmol Vis Sci. 2020 Jan 23;61(1):3. doi: 10.1167/iovs.61.1.3.
The purpose of this study was to investigate the expression of death ligands in the lacrimal glands (LGs), identify upstream factors that regulate their expression, and determine the functional roles of these factors in the pathogenesis of dry eye disease (DED).
For DED experiment, ex vivo coculture system with LG and in vivo murine model using a controlled environment chamber were utilized. C57BL/6 mice and hypoxia-inducible factor (HIF)-1α conditional knockout (CKO) mice were used. Immunohistochemical staining, polymerase chain reaction, and immunoblotting were performed to determine levels of death ligands including tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in DED-induced LGs. Additionally, acinar cell and CD45+ cell apoptosis was determined with neutralizing TRAIL treatment.
Desiccating stress significantly increased HIF-1α expression in LG-acinar cells. Furthermore, HIF-1α deficiency significantly enhanced the infiltration of CD45+ inflammatory cells in LG and induced LG-acinar cell death. Meanwhile, only TRAIL expression was increased in DED-LG, but abrogated in HIF-1α CKO. Interestingly, the main source of TRAIL was the CD45- LG-acinar cells, but not CD45+ immune cells after DED induction. Using ex vivo coculture system, we confirmed LG-induced apoptosis of immune cells via HIF-1α-mediated TRAIL secretion following DED. Consistent with ex vivo, the insufficiency of HIF-1α and TRAIL enhanced recruitment of inflammatory cells to the LG and subsequently exacerbated ocular surface damage in DED mice.
Our findings offer novel insight into the regulatory function of acinar cell-derived TRAIL in limiting inflammatory damage and could be implicated in the development of potential therapeutic strategies for DED.
本研究旨在探讨死亡配体在泪腺（LG）中的表达，鉴定调控其表达的上游因子，并确定这些因子在干眼症（DED）发病机制中的功能作用。
对于 DED 实验，使用 LG 的离体共培养系统和使用受控环境室的体内小鼠模型。使用 C57BL/6 小鼠和缺氧诱导因子（HIF）-1α条件敲除（CKO）小鼠。进行免疫组织化学染色、聚合酶链反应和免疫印迹，以确定包括肿瘤坏死因子相关凋亡诱导配体（TRAIL）在内的死亡配体在 DED 诱导的 LG 中的水平。此外，用中和 TRAIL 处理来确定腺泡细胞和 CD45+细胞的凋亡。
干燥应激显著增加了 LG-腺泡细胞中的 HIF-1α表达。此外，HIF-1α 缺陷显着增强了 LG 中 CD45+炎症细胞的浸润，并诱导了 LG-腺泡细胞死亡。同时，只有 TRAIL 在 DED-LG 中增加，但在 HIF-1α CKO 中被阻断。有趣的是，TRAIL 的主要来源是 CD45-LG-腺泡细胞，而不是 DED 诱导后的 CD45+免疫细胞。使用离体共培养系统，我们证实了 LG 通过 DED 后 HIF-1α 介导的 TRAIL 分泌诱导免疫细胞凋亡。与离体结果一致，HIF-1α 和 TRAIL 的不足增强了炎症细胞向 LG 的募集，并随后加剧了 DED 小鼠的眼表损伤。
我们的研究结果提供了关于腺泡细胞源性 TRAIL 在限制炎症损伤中的调节功能的新见解，并可能暗示着针对 DED 的潜在治疗策略的发展。
