Abstract
Purpose :
Metabolic dysfunction and altered cellular energy metabolism are associated with retinal diseases such as diabetic retinopathy (DR). Our early work reported the implication of elevated Homocysteine (Hcy) or Hyperhomocysteinemia (HHcy) in DR. We reported elevated Hcy in both human and different animal models of DR and proposed Hcy as a marker and therapeutic target DR. Moreover, we reported alteration of retinal pigment epithelial cells (RPE) by HHcy and the potential role of the N-methyl-D-aspartate receptor (NMDAR) in mediating HHcy-induced retinal pathology. To support the energy needs for neuronal activities, RPE cells play an important role in transporting glucose from choroidal circulation to retinal neurons. The energy production in RPE cells was assessed under normal and high glucose conditions, as well as the involvement of NMDAR.
Methods :
The mitochondrial stress test was used to assess energy production in human retinal pigment epithelial cell (ARPE-19) treated with/without different concentrations of Hcy (20, 50, 100µM) under normal (5.5 mM, NG) and high glucose (30mM, HG). XFe96 seahorse assay was used to assess the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Additionally, cells were further evaluated for energy production in RPE cells in the presence /absence of NMDAR inhibitor MK-801.
Results :
Glycolysis in ARPE-19 cells indicated by (ECAR) was significantly increased by HHcy and decreased by HG. While mitochondrial respiration, indicated by (OCR) was significantly decreased in ARPE-19 cells in both HHcy and HG treatment versus control. Furthermore, blocking NMDAR by MK-801 was able to restore both glycolysis and mitochondrial respiration back to normal levels compared to the control.
Conclusions :
Metabolic dysfunction and altered cellular energy metabolism contribute to RPE dysfunction under HHcy and HG. This study highlights the importance of elevated Hcy during DR in altering metabolic dysfunction and energy production and proposes NMDAR as a possible therapeutic target during DR
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.