June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Potential role of tumor-necrosis factor (TNF) in the diabetes-induced loss of platelet-endothelial cell adhesion molecule-1 (PECAM-1) from retinal endothelial cells
Author Affiliations & Notes
  • Norman R Harris
    Molecular & Cellular Physiology, LSU Health Sciences Center, Shreveport, Louisiana, United States
  • Randa S Eshaq
    Molecular & Cellular Physiology, LSU Health Sciences Center, Shreveport, Louisiana, United States
  • Footnotes
    Commercial Relationships   Norman Harris, None; Randa Eshaq, None
  • Footnotes
    Support  NIH Grant EY025632
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 2513. doi:
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    • Get Citation

      Norman R Harris, Randa S Eshaq; Potential role of tumor-necrosis factor (TNF) in the diabetes-induced loss of platelet-endothelial cell adhesion molecule-1 (PECAM-1) from retinal endothelial cells. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2513.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : PECAM-1 is an endothelial surface molecule that plays important roles in endothelial cell junctions, barrier function, leukocyte transmigration, intracellular signaling, and cell survival. We have found a loss of PECAM-1 from the retinal microcirculation of diabetic rats; however, the mechanisms for this loss have yet to be identified. We hypothesize that elevated levels of TNF may be a contributing factor.

Methods : Male Wistar rats injected with streptozotocin (30 mg/kg/day for 3 consecutive days) were used as a model of type 1 diabetes, with vehicle-injected, age-matched rats serving as controls. Upon euthanasia 8 weeks later, retinas and plasma were obtained for analysis of PECAM-1 (immunostaining, Western blots) and TNF (Western blots). Additionally, rat retinal microvascular endothelial cells (RRMECs) were grown under normoglycemic (NG; 5 mM glucose) or hyperglycemic (HG; 25 mM) conditions for 6 days and analyzed for PECAM-1 and TNF. Finally, RRMECs under normal glucose were cultured for 24 hours along with TNF at concentrations of 0, 5, 10, 20, and 50 ng/ml.

Results : We found a significant loss of PECAM-1 from the retina in the in vivo model of diabetes, using both immunostaining (a 44% decrease in the superficial vasculature and an 86% decrease in the deep capillary layer; N=9 CON, 8 STZ; p<0.05) and Western blotting (61% decrease; N=13 CON, 13 STZ; p<0.05). A similar decrease in PECAM-1 was found in the in vitro model of hyperglycemia (65% decrease; N=3 NG, 3 HG; p<0.05). TNF protein levels increased by 70% in the plasma of diabetic rats (N=6 CON, 5 STZ; p<0.05) and by 74% in RRMECs (N=3 NG, 3 HG), even though the TNF protein levels decreased in the retinal tissue as a whole (by 36%, N=7 CON, 7 STZ; p<0.05). In vitro, TNF added to normoglycemic RRMEC cultures caused a decrease in PECAM-1 levels at concentrations of 20 and 50 ng/ml, but not at lower concentrations of 0-10 ng/ml.

Conclusions : Elevated TNF concentrations may play a role in the loss of PECAM-1 from the diabetic retinal microcirculation, as we find in retinal endothelial cell culture.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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