Pericytes Contribute to Retinal Vascular Cell Death in Diabetes: Role of Ephrin‐B2 Signaling

Abstract

Diabetes‐induced retinal vascular cell death aggravates diabetic retinopathy to proliferative stage and blindness. Pericytes (PCs) share the basement membrane with endothelial cells (EC) in retinal capillaries and play a crucial role in capillaries survival, stability, and angiogenesis. Ephrin‐B2 is a tyrosine kinase that has an essential role in PC/EC communication. The role of Ephrin‐B2 signaling in diabetic retinopathy is under investigation. In the present study, we hypothesized that diabetes alters Ephrin‐B2 signaling in pericytes that increase inflammation and retinal vascular cell death.MethodsType‐II diabetes was induced in male Wistar rats using high‐fat diet and streptozotocin. In vivo, selective reduction of Ephrin‐B2 expression in the retinal PC was achieved using the intraocular injection of AAV‐virus with NG2‐promoter that expresses EphrinB2 shRNA. Retinal trypsin‐digest was used to assess acellular capillary. Human retinal microvascular (HRP) were grown in glucose 25 mM/palmitate 200 uM (HG/Pal) to mimic diabetic conditions. Ephrin‐B2 was silenced in HRPs using siRNA. Cell migration was assessed using a scratch assay. Ephrin‐B2 expression, inflammatory (TNF‐alpha, JNK and IL‐1 beta) and apoptotic (PARP, Caspase‐3) markers were assessed via Western blot and immunohistochemistry.ResultsDiabetes increased Ephrin‐B2 expression in the retinal perivascular areas and pericytes that was confirmed with Western blot analysis. HRP treated with diabetic conditions showed a significant increase in Ephrin‐B2 expression that was associated with increased HPR migration. Silencing Ephrin‐B2 expression significantly reduced PC migration. Increased Ephrin‐B2 expression in pericytes in diabetes was accompanied with an increase in inflammatory markers TNF‐alpha, JNK and IL‐1 beta. In parallel diabetes increases PARP and caspase‐3 cleavage in diabetic retina. Silencing Ephrin‐B2 in retinal PCs decreased retinal vascular inflammation and apoptosis that was in parallel with the decrease in the number of acellular capillaries in retinas of diabetic rats.ConclusionOur results provide novel evidence that diabetes increases Ephrin‐B2 signaling in retinal pericytes that increase retinal vascular inflammation and death. These results identify pericytes‐Ephrin‐B2 signaling as a novel therapeutic target for diabetic retinopathy.Support or Funding InformationAHA, 16SDG30270013 to MA.SUSOP Excellence in Pharmacy Research award to MC.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.