title: TGFβ induces BIGH3 expression and human retinal pericyte apoptosis: a novel pathway of diabetic retinopathy.
abstract: PurposeOne of the earliest hallmarks of diabetic retinopathy is the loss of retinal pericytes. However, the mechanisms that promote pericyte dropout are unknown. In the present study, we propose a novel pathway in which pericyte apoptosis is mediated by macrophages, TGFβ and pro-apoptotic BIGH3 (TGFβ-induced Gene Human Clone 3) protein.Patients and methodsTo elucidate this pathway, we assayed human retinal pericyte (HRP) apoptosis by TUNEL assay, BIGH3 mRNA expression by qPCR, and BIGH3 protein expression by western blot analysis. HRP were treated with BIGH3 protein, TGFβ1 and TGFβ2 and inhibition assays were carried out by blocking with antibodies against BIGH3. The distribution of BIGH3 and CD68+macrophages were compared in a post-mortem donor eye with 7-year history of Type II diabetes and histopathogically confirmed non-proliferative diabetic retinopathy (NPDR).ResultsTGFβ induced a significant increase in BIGH3 mRNA and protein expression, and HRP apoptosis. BIGH3 treatment showed HRP undergo apoptosis in a dose-dependent manner. At 5 μg/ml, BIGH3 induced 3.5-times more apoptosis in HRP than in retinal endothelial cells. TGFβ induced apoptosis was inhibited by blocking with antibodies against BIGH3. In an example of NPDR, BIGH3 accumulated within the walls of the inner retina arterioles. Macrophage infiltrates were frequently associated with these vessels and the inner nuclear layer.ConclusionTogether with our previously published results on macrophage-induced retinal endothelial cell apoptosis, the present study supports a novel inflammatory pathway mediated by macrophages and the BIGH3 protein leading to HRP apoptosis. As shown in human post-mortem globes, these observations are clinically relevant, suggesting a new mechanism underlying pericyte dropout during NPDR.
authors: Department of Biology, The University of Texas at San Antonio, San Antonio, TX, USA.
authors: B S
authors: BS
authors: Betts-Obregon
authors: Department of Biology, The University of Texas at San Antonio, San Antonio, TX, USA.
authors: A A
authors: AA
authors: Mondragon
authors: Department of Biology, The University of Texas at San Antonio, San Antonio, TX, USA.
authors: A S
authors: AS
authors: Mendiola
authors: Department of Biology, The University of Texas at San Antonio, San Antonio, TX, USA.
authors: R G
authors: RG
authors: LeBaron
authors: Department of Biochemistry, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors: R
authors: R
authors: Asmis
authors: Departments of Ophthalmology and Pathology&Anatomic Sciences, State University of New York at Buffalo, Buffalo, NY, USA.
authors: T
authors: T
authors: Zou
authors: Departments of Ophthalmology and Pathology&Anatomic Sciences, State University of New York at Buffalo, Buffalo, NY, USA.|Departments of Ophthalmology and Pathology, University of Mississippi Medical Center, Jackson, MS, USA.|Research and Development Service, G.V. (Sonny) Montgomery Veterans Affair Medical Center, Jackson, MS, USA.
authors: F
authors: F
authors: Gonzalez-Fernandez
authors: Department of Biology, The University of Texas at San Antonio, San Antonio, TX, USA.|Department of Biochemistry, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors: A T
authors: AT
authors: Tsin
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D001160:Arterioles / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000473:pathology; D016326:Extracellular Matrix Proteins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008264:Macrophages / Q000166:cytology; D020286:Pericytes / Q000187:drug effects* / Q000473:pathology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D012171:Retinal Vessels / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology*; D000099222:betaIG-H3 Protein; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2; D000099222:betaIG-H3 Protein; C067980:CD68 antigen, human; D000097382:CD68 Molecule