Macular and peripheral distribution of ICAM-1 in the humanchoriocapillaris and retina

[摘要] Purpose: In order to understand the extent of choriocapillaryendothelial cell activation in different topographic regions of the eye,we sought to compare the localization of intercellular adhesionmolecule-1 (ICAM-1) in macular and peripheral regions of human eyes.Methods: Sections of sucrose-embedded human donor eyes that includedthe macula and ora serrata were evaluated for ICAM-1 and ICAM-2immunoreactivity with monoclonal and polyclonal antibodies. Patterns ofICAM-1 labeling in peripheral and macular regions were examined in 20eyes. Morphometric analyses of anti-ICAM-1 labeling intensity in thechoriocapillaris were performed using ImageJ software on a series ofmacular and extramacular punches from nine eyes. Quantitative PCRanalysis for ICAM-1 mRNA was performed on the RPE-choroid from the sameregions from six of the same eyes, and Western blots of samples treatedor untreated with N-glycosidase were performed to compare retinal andchoroidal ICAM-1.Results: ICAM-1 labeling of the choriocapillaris was typically moreintense in the macula than in the peripheral choroid in human donor eyes(14/20). ICAM-2 was also detected in the choriocapillaris and retinalvessels. Morphometric measurements confirmed a significantmacular-extramacular difference in ICAM-1 in six of nine eyes (p<0.05), with 1 of 9 eyes showing the opposite pattern. This pattern wasnot noted for endogenous alkaline phosphatase or ICAM-2. The oppositepattern was noted in the external limiting membrane (ELM), whichexhibited more intense ICAM-1 labeling in the far periphery than in themacula. On Western blots, choroidal ICAM-1 exhibited a greater molecularweight than the retinal form, with most of the apparent weightdifference due to N-linked carbohydrate chains.Conclusions: The regional differences in ICAM-1 distribution in thechoriocapillaris may indicate that this region is subject to increasedleukocyte trafficking. In view of the role of inflammatory processes inage-related macular degeneration (AMD), we propose that the higher levelof ICAM-1 protein in the macular choriocapillaris may impart greatersusceptibility of the macula to immune cell-mediated damage in AMD.

[学科分类] 生物化学/生物物理