title: TNF-α disrupts morphologic and functional barrier properties of polarized retinal pigment epithelium.
abstract: Retinal pigment epithelial (RPE) cells form a blood-ocular barrier, and their polarized property is crucial for maintaining the barrier functions. Tumor necrosis factor alpha (TNF-α), a major pleotropic inflammatory cytokine that disrupts the barrier function and eventual angiogenesis, is expressed in the choroidal neovascularizations of age-related macular degeneration eyes. Thus, it most likely plays an important role in the progression of the disease. The purpose of this study was to compare the effects of TNF-α on the barrier function of polarized RPE cells. Non-polarized RPE cells were used as negative controls. Isolated porcine RPE cells were seeded on Transwell™ membranes. The polarization of the RPE cells was determined by their high transepithelial electrical resistance (TER >150 Ω cm(2)) and by their differential secretion of vascular endothelial growth factor (lower layer/upper layer >2.5X). Polarized RPE cells were incubated with 10 ng/ml of TNF-α and the TER was measured. TNF-α significantly decreased the TER of polarized RPE cells by 17.6 ± 2.7% (P < 0.001) of the control at 24 h and that of non-polarized RPE cells by 5.4 ± 6.5% (P = 0.401). The p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, blocked the effects of TNF-α of decreasing the TER. Cell junction-related molecules, e.g., ZO-1, located between cells in control RPE cells, were disassembled by TNF-α, and this breakdown was suppressed by SB203580 in polarized RPEs. These results indicate that the breakdown of the RPE barrier function was caused exclusively by TNF-α in polarized RPEs, and TNF-α was acting through the p38 MAPK pathways. Investigations of polarized RPE cells should be more suitable for in vitro studies of the pathophysiology of retinochoroidal diseases.
authors: Department of Ophthalmology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka Kagoshima, 890-8520, Japan.
authors: Makoto
authors: M
authors: Shirasawa
authors: Shozo
authors: S
authors: Sonoda
authors: Hiroto
authors: H
authors: Terasaki
authors: Noboru
authors: N
authors: Arimura
authors: Hiroki
authors: H
authors: Otsuka
authors: Takehiro
authors: T
authors: Yamashita
authors: Eisuke
authors: E
authors: Uchino
authors: Toshio
authors: T
authors: Hisatomi
authors: Tatsuro
authors: T
authors: Ishibashi
authors: Taiji
authors: T
authors: Sakamoto
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D001813:Blood-Retinal Barrier / Q000187:drug effects*; D015153:Blotting, Western; D016764:Cell Polarity; D002478:Cells, Cultured; D017097:Electric Impedance; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D007093:Imidazoles / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D008855:Microscopy, Electron, Scanning; D011725:Pyridines / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism; D013552:Swine; D062725:Tight Junction Proteins / Q000378:metabolism; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000873:Anthracenes; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D011994:Recombinant Proteins; D062725:Tight Junction Proteins; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C432165:pyrazolanthrone; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580