title: Ameliorative effect of PACAP and VIP against increased permeability in a model of outer blood retinal barrier dysfunction.
abstract: Breakdown of outer blood retinal barrier (BRB) due to the disruption of tight junctions (TJs) is one of the main factors accounting for diabetic macular edema (DME), a major complication of diabetic retinopathy. Previously it has been shown that PACAP and VIP are protective against several types of retinal injuries. However, their involvement in the maintenance of outer BRB function during DME remains uncovered. Here, using an in vitro model of DME, we explored the effects of both PACAP and VIP. Human retinal pigment epithelial cells (ARPE19) were cultured for 26 days either in normal glucose (5.5 mM, NG) or in high glucose (25 mM, HG). In addition, to mimic the inflammatory aspect of the diabetic milieu, cells were also treated with IL-1β (NG+IL-1β and HG+IL-1β). Effects of PACAP or VIP on cells permeability were evaluated by measuring both apical-to-basolateral movements of fluorescein isothyocyanate (FITC) dextran and transepithelial electrical resistance (TEER). Expression of TJ-related proteins was evaluated by immunoblot. Results demonstrated that NG+IL-1β and, to a greater extent, HG+IL-1β significantly increased FITC-dextran diffusion, paralleled by decreased TEER. PACAP or VIP reversed both of these effects. Furthermore, HG+IL-1β-induced reduction of claudin-1 and ZO-1 expression was reversed by PACAP and VIP. Occludin expression was not affected in any of the conditions tested. Altogether, these finding show that both peptides counteract HG+IL-1β-induced damage in ARPE19 cells, suggesting that they might be relevant to the maintenance of outer BRB function in DME.
authors.affiliation: Department of Bio-Medical Sciences, University of Catania, Catania, Italy.
authors.forename: Soraya
authors.initials: S
authors.lastname: Scuderi
authors.forename: Agata Grazia
authors.initials: AG
authors.lastname: D'Amico
authors.forename: Alessandro
authors.initials: A
authors.lastname: Castorina
authors.forename: Rosa
authors.initials: R
authors.lastname: Imbesi
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Carnazza
authors.forename: Velia
authors.initials: V
authors.lastname: D'Agata
mesh_terms: D001813:Blood-Retinal Barrier; D002199:Capillary Permeability; D002460:Cell Line; D062445:Claudin-1 / Q000235:genetics / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D048909:Diabetes Complications / Q000378:metabolism / Q000473:pathology; D017097:Electric Impedance; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000378:metabolism; D015870:Gene Expression; D005947:Glucose / Q000494:pharmacology / Q000502:physiology; D006801:Humans; D053583:Interleukin-1beta / Q000502:physiology; D008269:Macular Edema / Q000378:metabolism / Q000473:pathology; D062793:Occludin / Q000235:genetics / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D055213:Retinal Pigment Epithelium / Q000473:pathology / Q000503:physiopathology; D019108:Tight Junctions / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C568108:CLDN1 protein, human; D062445:Claudin-1; D003911:Dextrans; C508585:IL1B protein, human; D053583:Interleukin-1beta; C568985:OCLN protein, human; D062793:Occludin; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; C015219:fluorescein isothiocyanate dextran; D014660:Vasoactive Intestinal Peptide; D016650:Fluorescein-5-isothiocyanate; D005947:Glucose