Effects of Latanoprost and Bimatoprost on the Expression of Molecules Relevant to Ocular Inflow and Outflow Pathways

Background and PurposeThe intraocular pressure (IOP)-lowering and side effects in response to different prostaglandin F2α analogues can be variable, but, the underlying basis for this difference remains unknown. This study investigated the differential changes of cellular proteins relevant to IOP-lowering effects of latanoprost and bimatoprost.MethodsThe human T lymphoblast (MOLT-3) cell line and immortalized human trabecular meshwork (iHTM) cells were studied by quantitative PCR and by immunofluorescence after treatment with either latanoprost or bimatoprost. New Zealand white rabbit eyes were treated topically with each agent and, following euthanasia, anterior segment tissues were studied with immunostaining.ResultsIn cultured MOLT-3 cells, mRNA expression of both c-fos and matrix metalloproteinase 9 increased significantly in response to each agent. In addition, there was little change in tissue inhibitor of metalloproteinase (TIMP)-3 mRNA, but a significant decrease in TIMP-4. Fibronectin mRNA in MOLT-3 cells was down-regulated with bimatoprost, but was up-regulated with latanoprost. Immunofluorescence analysis of iHTM cells showed that intracellular fibronectin was significantly decreased by bimatoprost, but was increased by latanoprost. Both latanoprost and bimatoprost increased mRNA expression of NF-кB p65 and decreased that of IкBα. Aquaporin-1 mRNA expression was significantly down-regulated by bimatoprost. Immunostaining also revealed a significant decrease of aquaporin-1 in the ciliary epithelium of New Zealand white rabbits after bimatoprost treatment.ConclusionsSimilarities in protein expression produced by latanoprost and bimatoprost in vitro may be relevant to the mechanism for their IOP-lowering effects in vivo. Differences in fibronectin expression and in aquaporin-1 expression in response to each agent may contribute to variability in the IOP-lowering efficacy in some studies.

背景与目的：不同前列腺素F2α（prostaglandin F2α）类似物的降眼压（intraocular pressure, IOP）效果及不良反应存在差异，但其差异的潜在机制仍未明确。本研究旨在探究拉坦前列素（latanoprost）与比马前列素（bimatoprost）的降眼压效应相关细胞蛋白的差异变化。方法：本研究采用定量聚合酶链式反应（quantitative PCR）与免疫荧光技术，分别以拉坦前列素与比马前列素处理人类T淋巴母细胞（MOLT-3）系及永生化人小梁网（immortalized human trabecular meshwork, iHTM）细胞开展实验。此外，对新西兰白兔眼部局部应用两种受试药物，安乐死后采用免疫染色技术对眼前节组织进行检测分析。结果：在培养的MOLT-3细胞中，经两种药物处理后，c-fos及基质金属蛋白酶9（matrix metalloproteinase 9）的mRNA表达均显著升高。此外，金属蛋白酶组织抑制剂（tissue inhibitor of metalloproteinase, TIMP）-3的mRNA水平无明显变化，而TIMP-4的mRNA水平则显著降低。MOLT-3细胞中的纤连蛋白（fibronectin）mRNA经比马前列素处理后表达下调，经拉坦前列素处理后则表达上调。对iHTM细胞的免疫荧光分析显示，比马前列素可显著降低细胞内纤连蛋白水平，而拉坦前列素则可升高该蛋白水平。拉坦前列素与比马前列素均可上调核因子κB p65（NF-κB p65）的mRNA表达，并下调核因子κB抑制剂α（IκBα）的mRNA表达。比马前列素可显著下调水通道蛋白-1（aquaporin-1）的mRNA表达。免疫染色结果还显示，新西兰白兔经比马前列素处理后，其睫状上皮（ciliary epithelium）中的水通道蛋白-1水平显著降低。结论：拉坦前列素与比马前列素在体外诱导的蛋白表达相似性，可能与其体内降眼压效应的作用机制相关。两种药物诱导的纤连蛋白及水通道蛋白-1表达差异，可能是部分研究中其降眼压疗效存在差异的原因。