title: Phosphomannopentaose sulfate (PI-88) inhibits retinal leukostasis in diabetic rat.
abstract: Retinal leukostasis, mediated by intracellular adhesion molecule-1 (ICAM-1) and vascular endothelial growth factor (VEGF), has been implicated in the pathogenesis of early diabetic retinopathy. Phosphomannopentaose sulfate (PI-88) is a highly sulfonated oligosaccharide which inhibits heparanase activity and competes with heparan sulfate binding to growth factors. In this study, we evaluated whether PI-88 could inhibit retinal leukostasis in strepotzotocin(STZ)-induced diabetic rat and elucidated the possible mechanisms. Diabetes was induced in Sprague-Dawley rats by intraperitoneal injection (i.p.) of STZ. Three months after induction, diabetic rats were administered PI-88 (25 mg/kg body weight) or vehicle solution daily via i.p. for 14 consecutive days. Leukostasis was analyzed on retinal flatmounts by concanavalin A and CD45 immunofluorescence staining. Retinal function was analyzed by electroretinography (ERG). ICAM-1 and VEGF levels in retinas were studied by Western blot and enzyme-linked immunosorbent assay (ELISA) respectively. The systemic administration of PI-88, but not vehicle, significantly decreased the number of adherent leukocytes in retinas by 52.24% (P<0.001) and led to significant preservation (about 50%, P<0.001) of scotopic ERG a- and b-wave amplitudes in treated diabetic rats as compared to those of diabetic control rats. These changes were associated with downregulation of ICAM-1 (45%, P<0.001) and VEGF (26.83+/-2.01 versus 40.8+/-3.24 pg/mg, P<0.01) in retinas of PI-88 treated diabetic rats as compared to those of diabetic control rats. PI-88 significantly inhibited retinal leukostasis and reversed retinal dysfunction by a mechanism that may include decreased ICAM-1 and VEGF expression in diabetic rats. Our data suggests that PI-88 is a promising agent for the treatment of diabetic retinopathy.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Opthalmic Center, Sun Yat-sen University, 54S, Xianlie Road, Guangzhou 510060, China.
authors.forename: Pingping
authors.initials: P
authors.lastname: Ma
authors.forename: Yan
authors.initials: Y
authors.lastname: Luo
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Zhu
authors.forename: Hongjie
authors.initials: H
authors.lastname: Ma
authors.forename: Jie
authors.initials: J
authors.lastname: Hu
authors.forename: Shibo
authors.initials: S
authors.lastname: Tang
mesh_terms: D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced; D003930:Diabetic Retinopathy / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D015536:Down-Regulation; D004596:Electroretinography; D007274:Injections, Intraperitoneal; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D018921:Leukostasis / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D009844:Oligosaccharides / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000187:drug effects* / Q000503:physiopathology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D009844:Oligosaccharides; D042461:Vascular Endothelial Growth Factor A; C120158:phosphomannopentaose sulfate; C467498:vascular endothelial growth factor A, rat; D018799:Intercellular Adhesion Molecule-1