title: Aquaporin 4 knockdown exacerbates streptozotocin-induced diabetic retinopathy through aggravating inflammatory response.
abstract: Diabetic retinopathy is a leading cause of reduced visual acuity and acquired blindness. Diabetes is known to alter the amount of retinal expression of the water-selective channels aquaporin 4 (AQP4). However, the function and impact of AQP4 in diabetic retinopathy is not well understood. In the present work, diabetes was induced by intraperitoneal injection of streptozotocin in Sprague-Dawley rats. Two weeks later, AQP4 shRNA (r) lentiviral particles or negative lentiviral particles were delivered by intravitreal injection to the eyes. Gene delivery was confirmed by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blotting analysis. Eight weeks later, BRB breakdown was measured using Evans blue dye. Images of retinal sections were obtained and the thicknesses of the retinas were determined. Retinal leukostasis measurement was performed using acridine orange leukocyte fluorography. The mRNA levels of IL-1β, IL-6, intercellular adhesion molecule 1 (ICAM-1), glial fibrillary acidic protein (GFAP) and vascular endothelial growth factor (VEGF) were determined using qRT-PCR method. AQP4 shRNA (r) lentiviral particles or negative lentiviral particles were transfected into rMC-1 cells to investigate its effect on inflammation induced by high glucose. Incubation with IL-1β or IL-6 was performed to test their effect on AQP4 expression in rMC-1 cells. In the current work, it was found that AQP4 expression was enhanced in the retina of diabetic rats. AQP4 knockdown led to exacerbation of retinopathy including enhancing retinal vascular permeability, retinal thickness, pro-inflammatory factors expression, and VEGF and GFAP expression in retinas of diabetic rats. AQP4 knockdown enhanced the expression of pro-inflammatory cytokines induced by high glucose in rMC-1 cells. In addition, AQP4 knockdown enhanced the release of IL-6 and VEGF from rMC-1 cells into the medium. Moreover, it was found that incubation with IL-1β or IL-6 suppressed AQP4 expression in rMC-1 cells. These results suggested that streptozotocin injection induced diabetes resulted in compensatory increases of AQP4 expression, and downregulation of AQP4 exacerbated diabetic retinopathy through aggravating inflammatory response, at last in part. Therefore, regulation of retinal function by AQP4 may attenuate diabetic retinopathy, offering a promising therapeutic strategy for diabetic retinopathy.
authors.affiliation: Department of Ophthalmology, First Affiliated Hospital of Second Military Medical University, Shanghai 200433, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Cui
authors.forename: Jin-Hua
authors.initials: JH
authors.lastname: Sun
authors.forename: Fen-Fen
authors.initials: FF
authors.lastname: Xiang
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Li
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000235:genetics*; D001786:Blood Glucose / Q000378:metabolism; D001813:Blood-Retinal Barrier; D015153:Blotting, Western; D003921:Diabetes Mellitus, Experimental / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D003930:Diabetic Retinopathy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D007378:Interleukins / Q000235:genetics; D018921:Leukostasis / Q000378:metabolism; D008297:Male; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D012171:Retinal Vessels / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics
chemical_list: C496032:Aqp4 protein, rat; D051401:Aquaporin 4; D001786:Blood Glucose; D005904:Glial Fibrillary Acidic Protein; D007378:Interleukins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D018799:Intercellular Adhesion Molecule-1