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Journal of Biomedicine and Biotechnology
Volume 2010 (2010), Article ID 289360, 10 pages
http://dx.doi.org/10.1155/2010/289360
Research Article

Neutrophils Compromise Retinal Pigment Epithelial Barrier Integrity

1The Arnold and Mabel Beckman Macular Research Center at the Doheny Eye Institute, University of Southern California, Los Angeles, CA 90033, USA
2Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
3Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
4Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA

Received 8 July 2009; Revised 15 October 2009; Accepted 19 November 2009

Academic Editor: Karl Chai

Copyright © 2010 Jiehao Zhou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We hypothesized that neutrophils and their secreted factors mediate breakdown of the integrity of the outer blood-retina-barrier by degrading the apical tight junctions of the retinal pigment epithelium (RPE). The effect of activated neutrophils or neutrophil cell lysate on apparent permeability of bovine RPE-Choroid explants was evaluated by measuring mannitol flux in a modified Ussing chamber. The expression of matrix metalloproteinase- (MMP-) 9 in murine peritoneal neutrophils, and the effects of neutrophils on RPE tight-junction protein expression were assessed by confocal microscopy and western blot. Our results revealed that basolateral incubation of explants with neutrophils decreased occludin and ZO-1 expression at 1 and 3 hours and increased the permeability of bovine RPE-Choroid explants by >3-fold ( ). Similarly, basolateral incubation of explants with neutrophil lysate decreased ZO-1 expression at 1 and 3 hours ( ) and increased permeability of explants by 75%. Further, we found that neutrophils prominently express MMP-9 and that incubation of explants with neutrophils in the presence of anti-MMP-9 antibody inhibited the increase in permeability. These data suggest that neutrophil-derived MMP-9 may play an important role in disrupting the integrity of the outer blood-retina barrier.