Department of Ophthalmology, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
Invest Ophthalmol Vis Sci. 2010 May;51(5):2664-70. doi: 10.1167/iovs.09-4195. Epub 2009 Dec 30.
The ageing of Bruch's membrane is associated with progressive reduction in the degradation of the capacity for ECM turnover mediated by the matrix metalloproteinase (MMP) system. In this study, the free and bound pools of all gelatinase species were quantified to aid in assessing the likelihood of reduced availability of pro-MMPs for activation in ageing Bruch's membrane.
Bruch's membrane from macular locations (10 eyes; donor age range, 21-84 years) was mounted in Ussing chambers and eluted with phosphate-buffered saline to release the free pool of MMPs. Free and bound pools of MMPs were subjected to gelatin zymography, and individual gelatinase species were quantified by densitometric scans.
The zymograms displayed six gelatinase species: four corresponding to the pro- and active forms of MMP-2 and -9 and two high-molecular-weight polymeric forms designated HMW1 and -2, corresponding to approximate molecular masses of 195 and 391 kDa, respectively. The ageing of Bruch's membrane was associated with an exponential increase in the percentage of pro-MMPs bound to the membrane (pro-MMP-2: %age bound = 0.54 exp(0.04 x age), r = 0.87, P < 0.01; and pro-MMP-9: %age bound = 5.0 exp(0.03 x age), r = 0.8, P < 0.01). A similar exponential increase was seen in the percentage of bound HMW1 species (%bound = 11.7 exp(0.018 x age; P < 0.05). The HMW2 species was virtually all bound to the membrane, but some release was observed in the very elderly.
The ageing of Bruch's membrane was associated with progressive sequestration of MMPs reducing the free concentration and potential for activation. These changes may underlie the reduction in degradation that leads to the age-related increase in the thickness of the membrane.
布鲁赫膜的老化与细胞外基质（ECM）周转率介导的基质金属蛋白酶（MMP）系统的降解能力逐渐降低有关。在这项研究中，定量测定了所有明胶酶的游离和结合池，以帮助评估老化布鲁赫膜中 MMP 前体的激活可用性降低的可能性。
从黄斑部位（10 只眼；供体年龄范围，21-84 岁）采集布鲁赫膜，置于 Ussing 室中，用磷酸盐缓冲盐水洗脱，释放 MMP 的游离池。对 MMP 的游离池和结合池进行明胶酶谱分析，并通过密度扫描定量测定各明胶酶的种类。
酶谱显示了六种明胶酶：四种分别对应 MMP-2 和 -9 的前体和活性形式，以及两种高分子量聚合物形式，分别命名为 HMW1 和 -2，其分子量约为 195 和 391 kDa。布鲁赫膜的老化与结合到膜上的前体 MMP 的百分比呈指数增长（MMP-2：%age 结合=0.54 exp（0.04 x 年龄），r=0.87，P<0.01；和 MMP-9：%age 结合=5.0 exp（0.03 x 年龄），r=0.8，P<0.01）。结合的 HMW1 形式的百分比也呈类似的指数增长（%bound=11.7 exp（0.018 x 年龄）；P<0.05）。HMW2 形式几乎全部与膜结合，但在非常年长的患者中观察到一些释放。
布鲁赫膜的老化与 MMP 的逐渐隔离有关，这降低了游离浓度和潜在的激活能力。这些变化可能是导致与年龄相关的膜厚度增加的降解减少的基础。
