Müller cell-derived VEGF is essential for diabetes-induced retinal inflammation and vascular leakage.
OBJECTIVE
Vascular endothelial growth factor (VEGF-A or VEGF) is a major pathogenic factor and therapeutic target for diabetic retinopathy (DR). Since VEGF has been proposed as a survival factor for retinal neurons, defining the cellular origin of pathogenic VEGF is necessary for the effectiveness and safety of long-term anti-VEGF therapies for DR. To determine the significance of Müller cell-derived VEGF in DR, we disrupted VEGF in Müller cells with an inducible Cre/lox system and examined diabetes-induced retinal inflammation and vascular leakage in these conditional VEGF knockout (KO) mice.


METHODS
Leukostasis was determined by counting the number of fluorescently labeled leukocytes inside retinal vasculature. Expression of biomarkers for retinal inflammation was assessed by immunoblotting of TNF-alpha, ICAM-1, and NF-kappaB. Vascular leakage was measured by immunoblotting of retinal albumin and fluorescent microscopic analysis of extravascular albumin. Diabetes-induced vascular alterations were examined by immunoblotting and immunohistochemistry for tight junctions, and by trypsin digestion assays for acellular capillaries. Retinal integrity was analyzed with morphologic and morphometric analyses.


RESULTS
Diabetic conditional VEGF KO mice exhibited significantly reduced leukostasis, expression of inflammatory biomarkers, depletion of tight junction proteins, numbers of acellular capillaries, and vascular leakage compared to diabetic control mice.


CONCLUSIONS
Müller cell-derived VEGF plays an essential and causative role in retinal inflammation, vascular lesions, and vascular leakage in DR. Therefore, Müller cells are a primary cellular target for proinflammatory signals that mediates retinal inflammation and vascular leakage in DR.
Wang
Juanjuan
J
Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China.
Xu
Xueliang
X
Elliott
Michael H
MH
Zhu
Meili
M
Le
Yun-Zheng
YZ
D000818:Animals; D001835:Body Weight; D002196:Capillaries / Q000473:pathology / Q000503:physiopathology; D017931:DNA Primers; D003921:Diabetes Mellitus, Experimental / Q000473:pathology / Q000503:physiopathology; D003930:Diabetic Retinopathy / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics; D007249:Inflammation; D018921:Leukostasis / Q000473:pathology / Q000503:physiopathology; D051379:Mice; D018345:Mice, Knockout; D009095:Mullerian Ducts / Q000502:physiology*; D016133:Polymerase Chain Reaction; D012160:Retina / Q000503:physiopathology*; D012171:Retinal Vessels / Q000473:pathology / Q000503:physiopathology; D019108:Tight Junctions / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000172:deficiency / Q000235:genetics / Q000502:physiology* / Q000627:therapeutic use
D017931:DNA Primers; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D042461:Vascular Endothelial Growth Factor A