Singapore National Eye Centre, Singapore.
Duke-NUS Medical School, Singapore.
Invest Ophthalmol Vis Sci. 2021 Feb 1;62(2):34. doi: 10.1167/iovs.62.2.34.
Aquaporins (AQPs) facilitate transmembrane osmotic water transport and may play a role in iris fluid conductivity, which is implicated in the pathophysiology of glaucoma. In this study, we compared the iris expression of AQPs and aqueous osmolality between primary angle closure glaucoma (PACG), primary open-angle glaucoma (POAG), and nonglaucoma eyes.
AQP1-5 transcripts from a cohort of 36 PACG, 34 POAG and 26 nonglaucoma irises were measured by quantitative real-time PCR. Osmolality of aqueous humor from another cohort of 49 PACG, 50 POAG, and 50 nonglaucoma eyes were measured using an osmometer. The localization of AQP1 in both glaucoma and nonglaucoma irises was determined by immunofluorescent analysis.
Of the five AQP genes evaluated, AQP1 and AQP2 transcripts were significantly upregulated in both PACG (3.48- and 8.07-fold, respectively) and POAG (3.12- and 11.58-fold, respectively) irises relative to nonglaucoma counterparts. The aqueous osmolalities of PACG (303.68 mmol/kg) and POAG (300.79 mmol/kg) eyes were significantly lower compared to nonglaucoma eyes (312.6 mmol/kg). There was no significant difference in expression of AQP transcripts or aqueous osmolality between PACG and POAG eyes.
PACG and POAG eyes featured significant increase in AQP1 and AQP2 expression in the iris and reduced aqueous osmolality compared to nonglaucoma eyes. These findings suggest that the iris may be involved in altered aqueous humor dynamics in glaucoma pathophysiology. Because PACG did not differ from POAG in both properties studied, it is likely that they are common to glaucoma disease in general.
水通道蛋白（AQP）促进跨膜渗透水转运，可能在房水流畅性中发挥作用，而后者与青光眼的病理生理学有关。在这项研究中，我们比较了原发性闭角型青光眼（PACG）、原发性开角型青光眼（POAG）和非青光眼眼的虹膜中 AQP 的表达和房水渗透压。
通过定量实时 PCR 测量了来自 36 例 PACG、34 例 POAG 和 26 例非青光眼虹膜的 AQP1-5 转录本。使用渗透压计测量了来自另一个包含 49 例 PACG、50 例 POAG 和 50 例非青光眼眼的房水渗透压。通过免疫荧光分析确定了 AQP1 在青光眼和非青光眼虹膜中的定位。
在所评估的五个 AQP 基因中，AQP1 和 AQP2 的转录物在 PACG（分别上调 3.48 倍和 8.07 倍）和 POAG（分别上调 3.12 倍和 11.58 倍）的虹膜中均显著上调，与非青光眼对照相比。PACG（303.68 mmol/kg）和 POAG（300.79 mmol/kg）眼的房水渗透压明显低于非青光眼眼（312.6 mmol/kg）。PACG 和 POAG 眼之间的 AQP 转录物表达或房水渗透压无显著差异。
PACG 和 POAG 眼的虹膜中 AQP1 和 AQP2 的表达显著增加，房水渗透压降低，与非青光眼眼相比。这些发现表明，虹膜可能参与了青光眼病理生理学中房水动力学的改变。由于在研究的两种特性中，PACG 与 POAG 之间没有差异，因此它们很可能是一般青光眼疾病所共有的。
