title: Neutrophils compromise retinal pigment epithelial barrier integrity.
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 [3H] 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 (P < .05). Similarly, basolateral incubation of explants with neutrophil lysate decreased ZO-1 expression at 1 and 3 hours (P < .05) 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.
authors.affiliation: The Arnold and Mabel Beckman Macular Research Center at the Doheny Eye Institute, University of Southern California, Los Angeles, CA 90033, USA.
authors.forename: Jiehao
authors.initials: J
authors.lastname: Zhou
authors.forename: Shikun
authors.initials: S
authors.lastname: He
authors.forename: Ning
authors.initials: N
authors.lastname: Zhang
authors.forename: Christine
authors.initials: C
authors.lastname: Spee
authors.forename: Peng
authors.initials: P
authors.lastname: Zhou
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ryan
authors.forename: Ram
authors.initials: R
authors.lastname: Kannan
authors.forename: David R
authors.initials: DR
authors.lastname: Hinton
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002829:Choroid / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D006651:Histocytochemistry; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000502:physiology*; D062793:Occludin; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D019108:Tight Junctions / Q000378:metabolism
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; D020780:Matrix Metalloproteinase 9