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Ashley Mackey, Gopalan Gnanaguru, Eun Young Choi, Dhanesh Amarnani, Patricia A D'Amore, Yin Shan Eric Ng; The PPAR-γ Agonist Troglitazone Protects RPE Cells from Oxidized LDL Induced NLRP3-inflammasome–Mediated Cell Death. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2288. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The retinal pigment epithelium (RPE) plays a critical role in lipid homeostasis in the retina. A growing body of evidence suggests that dysfunctional lipid metabolism, accumulation of oxidized low-density lipoprotein (ox-LDL) and inflammasome activation are associated with RPE dysfunction and the pathogenesis of dry AMD. We have previously shown that ox-LDL is cytotoxic for RPE by inflammasome-mediate pyroptosis. We hypothesize that activation of the peroxisome proliferator-activated receptors (PPARs) will increase lipid metabolism and suppress inflammation, and thereby rescue RPE cells from ox-LDL induced cell death.
ARPE-19 and/or primary human fetal RPE cells were treated for 48 hours with a range of concentrations of ox-LDL in the presence or absence of different agonists that selectively activate the three different PPAR isoforms: PPAR-α (fenofibrate 30 μM), PPAR-γ (troglitazone 0.55 μM), and PPAR-β/δ (bezafibrate 60 μM). Cell death was measured by lactate dehydrogenase release into the conditioned media. ARPE-19 cells were treated for 18 and 36 hours with ox-LDL in the presence or absence of the PPAR-γ agonist troglitazone, and fluorescent labeling with a LysoTracker probe and an anti-NF-kB antibody were used to examine lysosomal integrity and NF-kB activation by immunofluorescent staining. NLRP3-inflammasome activation was assessed by protein blot for cleaved caspase-1 and using the FAM-FLICA caspase-1 fluorescent probe assay.
The PPAR-γ selective agonist troglitazone significantly protected primary human RPE and ARPE-19 cells from ox-LDL induced dysfunction and cell death, while agonists selective for the PPAR-α and PPAR-β/δ isoforms did not protect the RPE. Troglitazone protected against ox-LDL induced lysosomal destabilization and suppressed the nuclear translocation and activation of NF-kB and inflammation induced by ox-LDL. Troglitazone also suppressed activation of caspase-1, suggesting that its protective effect is mediated by inhibition of inflammasome activation.
The PPAR-γ selective agonist troglitazone protects RPE cells from ox-LDL–induced cell death by suppressing inflammation, preserving lysosomal integrity and ultimately preventing NLRP3-inflammasome activation. These preliminary data highlight PPAR-γ as a potential therapeutic target for protecting RPE in AMD.
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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