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Mohammed Abdelsaid, Amy Barrett, Maha Coucha; Increased EphrinB2 expression in pericytes contributes to retinal vascular death in diabetes.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3588.
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Diabetic retinopathy is the leading cause of blindness in working-age worldwide. Pericytes (PC) play a pivotal role in vascular integrity and angiogenesis. EphrinB2 is a ligand for EphB4, a tyrosine kinase receptor that mediates plenty of PC/ endothelial cell (EC) interactions during development, survival, and angiogenesis. Yet, the role of pericyte EphrinB2 signaling in diabetes is unclear. In the present study, we test the hypothesis that the increased EphrinB2 expression in pericytes contributes to retinal vascular death in diabetes.
Type-II diabetes was induced in male Wistar rats using low dose streptozotocin and high-fat diet for 8 weeks. Selective reduction of EphrinB2 expression in the retinal PC was achieved using intraocular injection of AAV-virus with NG2-promoter. Retinal vascular cell death was assessed with retinal trypsin-digest (acellular capillary) and Western Blot for apoptotic markers (Caspase-3 and PARP). Human microvascular pericytes (HMPCs) were grown in high glucose 25 mM/palmitate 200 uM (HG/Pal) to mimic diabetic conditions. PC/EC co-culture was used to assess PC/EC interaction and angiogenic functions after silencing EphrinB2 in PC. Oxygen-induced retinopathy (OIR) mouse model was used to assess retinal neovascularization after AAV or EphB4FC injections, an EphrinB2 antagonist.
Our results showed increased EphrinB2 expression in diabetic retina and HMPC treated with HG/Pal compared to control, which was associated with an increase in apoptotic markers. Selective reduction of EphrinB2 in PC was confirmed by Western blot and immunohistochemical studies. Silencing EphrinB2 in PC decreased the number of acellular capillaries and caspase-3 cleavage in retinas of diabetic rats. Silencing EphrinB2 expression in PC decreased PC migration and PC/EC tube formation. Retinal tufts formation and apoptotic markers were significantly reduced via reduction of EphrinB2 in PC in OIR mouse model. Injection of EphB4Fc decreased EphrinB2 activation, retinal tufts, and apoptosis.
Our findings emphasize the crucial role of PC in retinal vascular death in diabetes. EphrinB2 signaling is a promising therapeutic target to improve vascular integrity in diabetes. Further studies are required to reveal the molecular mechanism of the EphrinB2 signaling in PC/EC interaction in diabetes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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