Abstract
Purpose::
To define and analyze the topographical and involutional changes of human Bruch’s membrane proteome.
Methods::
6.5 mm circular explants of human Bruch’s membrane were harvested from the macula and periphery of 6 young (<50) and old (>65) donor eyes using an excimer laser. Proteins were extracted using an optimized extraction protocol and separated using two-dimensional gel electrophoresis. The differential protein expression were determined by software analysis, subject to in-gel digestion, and identified by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and electrospray ionization-quadruple time-of-flight MS/MS (ESI-Q-TOF MS/MS). Results were confirmed with Western blotting analysis.
Results::
279 different proteins were identified in human Bruch’s membrane. 98 of the proteins were common in all samples; however 16 proteins were specific to macula. Macular samples revealed higher expression of heat shock protein 90 and 86, as well as antioxidant proteins, such as tripeptidyl peptidase, antioxidant protein-2 and superoxide dismutase among others. Aging was associated with the appearance of multiple complement factors (C1q, C3, C7, C8 and Factor H) and fibroblast growth factor in both peripheral and macular Bruch’s membrane. Aged macular Bruch’s membrane revealed significant decrease in hemoglobin beta chain.
Conclusions::
Human Bruch’s membrane proteome shows topographical and age-related alterations reflecting cellular events in respective locations. Qualitative and quantitative changes in Bruch’s membrane proteome may initiate and/or augment the cellular pathologies leading to macular degeneration.
Keywords: age-related macular degeneration • proteomics • Bruch's membrane