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Valerie Fontaine, Mylène Fournié, Elodie Monteiro, Constance Nivoit, Serge CAMELO, Pierre Dilda, Stanislas Veillet, Jose Alain Sahel, Rene Lafont; BIO201 PROTECTS RETINAL PIGMENT EPITHELIUM AGAINST A2E-INDUCED PHOTOTOXICITY THROUGH A MECHANISM INVOLVING THE PPARS. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5385. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
We previously showed that BIO201 (API = norbixin) protects retinal pigmented epithelium cells (RPE) against phototoxicity induced by A2E and blue light illumination. The peroxisome proliferator-activated receptors (PPARs) have been shown to be involved in the pathogenesis of age-related macular degeneration (AMD). This study tested the hypothesis that BIO201 is able to counteract the A2E-induced inflammation through a PPAR-dependent mechanism.
The effect of PPAR’s agonists and antagonists on the photoprotective action of BIO201 was quantified by a cell viability assay using primary cultures of porcine RPE cells challenged with A2E and blue light illumination. The affinity of BIO201 for the 3 PPAR subtypes was determined by competitive binding studies employing radiolabelled ligands. The effects of different treatments on the transactivation or transrepression activity of PPARs, AP-1 and NF-κB were measured in RPE cells using full length or chimeric constructs and luciferase reporter genes. The phosphorylation of ERK and Akt was assessed by western blot. All experiments were performed at least 3 times and one-way ANOVA followed by Dunnett’s tests were performed for statistical analyses.
BIO201 and PPARα (sulindac) or PPARβ/δ (GW0742) agonists protected RPE cells (80.6%, 52.3% and 72% cell survival, respectively, vs. 33.6% in control (p<0.001)), whereas a selective PPARγ agonist (rosiglitazone) was inactive. BIO201 protection was partly reversed by PPARα (MK886) and PPARβ/δ (GSK3787) antagonists (65% (p<0.01) and 43% (p<0.001) respectively) but not by PPARγ antagonist (T0070907) (74% p>0.05), suggesting that PPARα and β/δ are involved in RPE protection induced by BIO201. BIO201 bound PPARα and PPARγ with Ki values of 16.5 and 1.15 μM, respectively, but it did not exhibit any agonistic activity on the three PPARs. Accordingly, BIO201 did not stimulate the transactivation activity of any PPAR in RPE cells transfected with PPARs constructs. In addition, BIO201 blocked A2E-induced activation of ERK and Akt and transactivation of AP-1 and NF-κB, suggesting an anti-inflammatory effect.
Our data lead us to propose that BIO201 counteracts A2E effects by a selective stimulation of the transrepression activity of PPARα and PPARβ/δ, a mechanism that would also explain the requirement of high concentrations of PPAR agonists for their protective activity.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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