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Shujie Zhang, Ning Yu, Rong Zhang, Shenghai Zhang, Jihong Wu; Interleukin-17A Induces IL-1β Secretion From RPE Cells Via the NLRP3 Inflammasome. Invest. Ophthalmol. Vis. Sci. 2016;57(2):312-319. doi: 10.1167/iovs.15-17578.
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© ARVO (1962-2015); The Authors (2016-present)
Inflammasome activation and IL-1β production have been proposed to have an important role in age-related macular degeneration (AMD). Growing evidence is emerging for involvement of interleukin-17A (IL-17A) in AMD pathogenesis. We investigated the effects of IL-17A on the activation of inflammasome and production of IL-1β in primary human RPE cells.
Primary human RPE cells were isolated and cultured for the following experiments. Expression patterns of IL-17 receptor A (IL-17RA), IL-17 receptor C (IL-17RC), and ACT1 were analyzed by RT-PCR, flow cytometry, and immunofluorescence. IL-17A was added to the cell cultures, and cytokine expression, signaling pathways, and inflammasome machinery were investigated using real-time RT-PCR, ELISA, Western blot, flow cytometry, and small interfering RNA.
Retinal pigment epithelial cells constitutively expressed IL-17RA, IL-17RC, and ACT1. IL-17A upregulated the mRNA levels of pro-IL-1β, IL-8, CCL2, and CCL20, as well as the protein level of IL-1β. IL-17A induced the phosphorylation of Akt, Erk1/2, p38 MAPK, and NF-κB p65 in RPE cells. Blocking NF-κB attenuated IL-17A–induced expression of pro-IL-1β mRNA. IL-17A enhanced pro-caspase-1 and NLRP3 mRNA expression. Inhibiting caspase-1 activity and silencing NLRP3 decreased IL-1β secretion, confirming NLRP3 as the IL-17A–responsive inflammasome on the posttranscriptional level. The mechanism of IL-17A–triggered NLRP3 activation and subsequent IL-1β secretion was found to involve the generation of reactive oxygen species.
Our results suggest that IL-17A triggers a key inflammatory mediator, IL-1β, from RPE cells, via NLRP3 inflammasome activation, holding therapeutic potential for AMD.
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