Lack of synergistic neuroprotection and Sirt1 upregulation by Elovanoids (ElVs) and Neuroprotectin D1 (NPD1) against uncompensated oxidative stress in human retinal pigment epithelial cells (RPE).

Abstract

Purpose : Cell survival under unfavorable stress is important for the prevention of diseases caused by retinal degeneration. Sirtuin1 (SIRT1) and Prohibitin type1 (PHB1) are two proteins found in retinal pigment epithelial (RPE) cells that maintain homeostasis condition of the cells. As we age, an accumulation of oxidative stress, inflammation, in the retina which leads to two important eye diseases AMD, (age-related macular degeneration) or glaucoma. Bioactive lipid molecule, Docosahexaenoic acid (DHA), and its derivative, Neuroprotectin D1 (NPD1) protects against neuronal cell death under oxidative stress. The purpose of this study is to investigate the involvement of novel bioactive derivatives of 32:6 and 34:6 Elovanoids also derived from DHA and NPD1 in Sirtuin - Prohibitin signaling in the cell survival of primary cultures of human retinal pigment epithelial (ABC) cells under UOS.

Methods : Methods: A programmed cell death (apoptosis) study was conducted to measure the percentage of cell death under UOS (induced by H₂O₂ and TNF-α) with or without the presence of ELVs and NPD1. A more accurate and unbiased Western blot (WB) analysis (Jess) followed for the expression of SIRT1 and PHB1 in ABC cells under stressed conditions. The specificity of SIRT1 inductions by Elovanoids were tested by comparing the expression of different type of Sirtuins (either nuclear, or cytoplasmic or mitochondrial origin) using the ABC cell extracts.

Results : Our results showed that the two newly discovered novel class of lipid mediators ELV-N32 and ELV-N34 were neuroprotective under uncompensated oxidative stress (UOS) in RPE. The specificity of SIRT1 and PHB1 inductions by Elovanoids and NPD1 were specific as other biologically active compounds (RVE1, RVD1, LPX-A4 and Epi-15-LPX-A4) were ineffective. Moreover, our experimental results showed that the bioactivity mediated by ELVs and NPD1 is additive rather than synergistic.

Conclusions : Our findings uncovered and characterized a novel pro homeostatic and neuroprotective signaling mechanism in RPE cell survival under stress that aims to reveal potential therapeutic targets for retinal degenerations.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.