TY - JOUR
T1 - TGFβ induces BIGH3 expression and human retinal pericyte apoptosis
T2 - A novel pathway of diabetic retinopathy
AU - Betts-Obregon, B. S.
AU - Mondragon, A. A.
AU - Mendiola, A. S.
AU - Lebaron, R. G.
AU - Asmis, R.
AU - Zou, T.
AU - Gonzalez-Fernandez, F.
AU - Tsin, A. T.
N1 - Funding Information:
This work was supported by the National Institute on Minority Health and Health Disparities (G12MD007591), the National Heart Lung and Blood Institute (R01HL70963) of the National Institutes of Health, The San Antonio Life Sciences Institute Grant (SALSI) from Texas Higher Education Coordinating Board, National Institutes of Health (R01 EY09412) (FG-F); Merit Review Award 101BX007080 from the Biomedical Laboratory Research and Development Service of the Veterans Affair Office of Research and Development (FG-F); an unrestricted grant from Research to Prevent Blindness to the Department of Ophthalmology at State University of New York at Buffalo; NIH grant U42-OD011158 to the National Disease Research Interchange for the Human Tissue and Organ Research Resource. Research Start-Up Awards from Research Mississippi! and the the VA office of Research Development (FG-F).
PY - 2016/12/1
Y1 - 2016/12/1
N2 - 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.
AB - 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.
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U2 - 10.1038/eye.2016.179
DO - 10.1038/eye.2016.179
M3 - Article
C2 - 27564721
AN - SCOPUS:85002809366
VL - 30
SP - 1639
EP - 1647
JO - Eye
JF - Eye
SN - 0950-222X
IS - 12
ER -