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A. A. Hussain, A. Kumar, A. El-Osta, J. Marshall; Level and Distribution Patterns of Active Matrix Metalloproteinase Enzymes (MMPs) in Ageing Human Bruch’s Membrane. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4934.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the effect of age on levels of active MMPs 2&9 in the soluble and bound fraction of human Bruch’s membrane.
Freshly isolated Bruch’s-choroid preparations (14 eyes, age range 21-88 years) were mounted in Ussing chambers and eluted with phosphate buffered saline (PBS) to remove the soluble fraction. The eluted fractions together with the membrane complex were then subjected to gelatine zymography and active MMPs quantified by densitometry.
The percentage of gelatinase activity due to the active forms of MMPs 2&9 in intact preparations of Bruch’s was determined to be 10.6 ± 7.4%(11) and 1.6 ±1.7 %(11) respectively. In aged donors, over the age of 70 years, levels of active MMP-2 were considerably elevated. There was no age-related variation in the levels of active MMP-9. After removing the soluble component, the levels of active MMPs 2&9 in the membrane fraction was 15.7 ± 11.0% (9) and 0.4 ± 0.6% (9) respectively. The bound and un-releasable pool of active MMPs 2&9 was 35 ± 38%(9) and 16 ± 32% (9) respectively.
Increased active MMP-2 levels in the elderly may be indicative of the need for membrane turnover. However the low levels of active MMP-9 and the high sequestration of active forms in ageing Bruch’s suggests that the rejuvenation process is compromised leading to the functional deterioration of the membrane.
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