Smith-Thomas L C, Richardson P S, Rennie I G, Palmer I, Boulton M, Sheridan C, MacNeil S
Clinical Sciences Center, Section of Medicine, Northern General Hospital, Division of Clinical Sciences, Sheffield, United Kingdom.
Curr Eye Res. 2000 Jul;21(1):518-29.
The aim of the study was to determine to what extent collagen gel contraction could be reduced by calcium and calmodulin antagonists and agents that elevate cyclic AMP in order to develop a pharmacological approach to prevent/arrest RPE contraction of epiretinal membranes in proliferative vitreoretinopathy. We also explored a possible role of pigment in collagen gel contraction.
We measured RPE mediated contraction of 3D collagen gels in the presence and absence of the calcium and calmodulin antagonists TMB8, Verapamil and Tamoxifen and the cAMP elevating agents IBMX and Forskolin. The effect of pigment on collagen gel contraction was assessed by comparing gel contraction mediated by RPE cells re-pigmented with melanin with that mediated by unpigmented RPE. The effect of IBMX on RPE proliferation was assessed using a BrdU ELISA and the effects of IBMX on RPE cytoskeleton and cell shape were assessed using Actin and Cytokeratin immunocytochemistry.
We report that both cAMP elevating agents and calcium and calmodulin antagonists reduce RPE mediated collagen gel contraction. Cyclic AMP elevation was more effective than a reduction in calcium in reducing contraction. There were no significant advantages in combining both approaches. The presence of melanin had no effect on gel contraction. Calcium antagonists and particularly agents which elevate cAMP caused RPE cells in collagen gels to extend fewer and shorter processes. cAMP elevation in particular caused RPE cells to become more rounded and develop arborized cell processes. Immunostaining for actin and cytokeratin revealed changes in cytoskeletal organisation in response to IBMX in that cells contained less actin than untreated cells and concentrated cytokeratins more centrally.
We have identified two possible pharmacological approaches which may provide a new direction for preventing or slowing down the development of PVR.
本研究的目的是确定钙和钙调蛋白拮抗剂以及提高环磷酸腺苷（cAMP）的药物能在多大程度上减少胶原凝胶收缩，从而开发一种药理学方法来预防/阻止增生性玻璃体视网膜病变中视网膜色素上皮（RPE）收缩性视网膜前膜的形成。我们还探讨了色素在胶原凝胶收缩中的可能作用。
我们在存在和不存在钙和钙调蛋白拮抗剂三甲基溴化铵（TMB8）、维拉帕米和他莫昔芬以及cAMP升高剂异丁基甲基黄嘌呤（IBMX）和福斯高林的情况下，测量了RPE介导的三维胶原凝胶收缩。通过比较黑色素重新着色的RPE细胞介导的凝胶收缩与未着色RPE介导的凝胶收缩，评估色素对胶原凝胶收缩的影响。使用BrdU酶联免疫吸附测定（ELISA）评估IBMX对RPE增殖的影响，并使用肌动蛋白和细胞角蛋白免疫细胞化学评估IBMX对RPE细胞骨架和细胞形状的影响。
我们报告说，cAMP升高剂以及钙和钙调蛋白拮抗剂均可减少RPE介导的胶原凝胶收缩。在减少收缩方面，cAMP升高比降低钙更有效。两种方法联合使用没有显著优势。黑色素的存在对凝胶收缩没有影响。钙拮抗剂，特别是提高cAMP的药物，使胶原凝胶中的RPE细胞伸出的突起更少、更短。特别是cAMP升高使RPE细胞变得更圆，并形成树状细胞突起。肌动蛋白和细胞角蛋白的免疫染色显示，响应IBMX，细胞骨架组织发生了变化，即细胞中的肌动蛋白比未处理的细胞少，细胞角蛋白更集中在中央。
我们确定了两种可能的药理学方法，这可能为预防或减缓增生性玻璃体视网膜病变的发展提供新的方向。
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