Purchase this article with an account.
Susannah Maria Spieker, Lena K Mohr, Carolina Brandstetter, Andrea V Hoffmann, Frank G Holz, Tim U Krohne; Inflammasome-related cytokine secretion secondary to lysosomal membrane permeabilization in retinal pigment epithelial cells. Invest. Ophthalmol. Vis. Sci. 2014;55(13):365.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Photooxidative damage to the retinal pigment epithelium (RPE) as well as chronic inflammatory processes in the sub-RPE space are involved in the pathogenesis of age-related macular degeneration (AMD). We have shown that lipofuscin phototoxicity can activate the NLRP3 inflammasome in RPE cells by inducing lysosomal membrane permeabilization (LMP). Here, we investigate the effects of LMP-induced inflammasome activation on the secretion of inflammatory and angiogenic cytokines related to the pathogenesis of AMD.
LMP was induced in primary human RPE cells and ARPE-19 cells either by Leu-Leu-OMe or by incubation with 4-hydroxnonenal-modified photoreceptor outer segments (HNE-POS) to induce lipofuscinogenesis and subsequent irradiation with blue light (0.8 mW/cm2) for up to 6 hours. LMP was quantified by flow cytometry by means of acridine orange staining. Cytokine secretion was measured using dot blot antibody arrays (RayBiotech) and specific ELISAs (R&D Systems). Polarized cytokine secretion was analyzed in RPE cells cultured on permeable membranes. Paracrine cytokine effects were investigated by incubating human vascular endothelial cells (HUVEC) with RPE-conditioned media.
Secretion levels of 42 inflammation- and angiogenesis-related cytokines were investigated in RPE cells following LMP induction. LMP resulted in NLRP3 inflammasome activation with increased secretion of the interleukins IL-1β and IL-18. In contrast, secretion of vascular endothelial growth factor (VEGF) was significantly decreased. Migration and proliferation of vascular endothelial cells incubated with conditioned media of LMP-treated RPE cells was reduced. Specific inhibition of caspase-1 or cathepsin B prevented inflammasome-related cytokine secretion.
Activation of the NLRP3 inflammasome by lipofuscin-mediated lysosomal membrane permeabilization in RPE cells results in the release of pro-inflammatory interleukins with simultaneous reduction of constitutive VEGF secretion. While these results support a potential role of inflammasome activation in lipofuscin-related RPE cell damage in early-stage and atrophic AMD, they argue against a direct involvement of the NLRP3 inflammasome in the development of neovascular AMD.
This PDF is available to Subscribers Only