Department of Biological Sciences, Allergan, Inc., Irvine, California 92612, USA.
Invest Ophthalmol Vis Sci. 2013 Jul 16;54(7):4782-90. doi: 10.1167/iovs.13-12363.
The goal of this study was to functionally compare prostaglandin E2 (PGE2)-sensitive receptors in human primary cells involved in conventional outflow.
The expression profile of prostaglandin (PG) receptors in primary cultures of human trabecular meshwork (TM) and Schlemm's canal (SC) cells were determined by quantitative-PCR. The functional activities of endogenous PGE2-sensitive receptors were evaluated using subtype-selective agonists and antagonists with cell impedance technology.
Agonist-sensitive EP1, EP2, and EP4 receptors were present in TM cells, all increasing cell stiffness (or contractility) in a dose-dependent manner. Rank order of efficacy (Emax) for agonists in TM cells were EP1 greater than EP2 greater than EP4 with EC50 1.1 μM, 0.56 μM, and 0.1 μM, respectively, and no functional EP3 receptors were found. Of the four EP receptor subtypes active in SC cells, EP1 and EP3 receptor activation increased cell stiffness, while EP2 and EP4 agonists dose-dependently decreased cell stiffness 47% and 23% with EC50 values of 170 nM and 69 nM, respectively. Consistent with these observations, the Rho kinase inhibitor Y-27632 decreased cell impedance (stiffness) of TM and SC cells (∼60%), while Rho GTPase activator thrombin caused cell impedance to increase in both cell types (168%-190%).
Cell impedance positively correlates with cellular stiffness/contractility. Because EP2/4 receptors caused decreased cell stiffness in SC, but not in TM cells, both receptors appear to mediate IOP lowering via changes in SC cell stiffness in the conventional outflow pathway.
本研究旨在从功能上比较参与传统流出途径的人原发性细胞中前列腺素 E2（PGE2）敏感受体。
通过定量 PCR 确定人小梁网（TM）和 Schlemm 管（SC）细胞原代培养物中前列腺素（PG）受体的表达谱。使用亚型选择性激动剂和拮抗剂通过细胞阻抗技术评估内源性 PGE2 敏感受体的功能活性。
TM 细胞中存在激动剂敏感的 EP1、EP2 和 EP4 受体，所有受体均以剂量依赖性方式增加细胞硬度（或收缩性）。TM 细胞中激动剂的效价（Emax）顺序为 EP1 大于 EP2 大于 EP4，EC50 分别为 1.1 μM、0.56 μM 和 0.1 μM，并且未发现功能性 EP3 受体。在 SC 细胞中四种 EP 受体亚型中，EP1 和 EP3 受体的激活增加了细胞硬度，而 EP2 和 EP4 激动剂则以剂量依赖性方式使细胞硬度分别降低了 47%和 23%，EC50 值分别为 170 nM 和 69 nM。与这些观察结果一致，Rho 激酶抑制剂 Y-27632 降低了 TM 和 SC 细胞的细胞阻抗（硬度）（约 60%），而 Rho GTPase 激活剂凝血酶使两种细胞类型的细胞阻抗增加（168%-190%）。
细胞阻抗与细胞硬度呈正相关。由于 EP2/4 受体使 SC 细胞的硬度降低，但 TM 细胞没有，因此这两种受体似乎通过改变 SC 细胞在传统流出途径中的硬度来介导眼压降低。
