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Matthew West, Folami Lamoke, Pamela M Martin, Manuela Bartoli; Inhibition of amyloid beta-induced inflammasome activation in human retinal pigmented epithelial cells by the farnesyl-transferase inhibitor FTI-277. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2324.
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© ARVO (1962-2015); The Authors (2016-present)
Increased evidence demonstrates that deposition of amyloid beta peptides (Abeta) plays a pathogenic role in age-related macular degeneration (AMD). In addition, inflammasome activation in retinal pigmented epithelial cells (RPE) has been linked to the induction of geographical atrophy (GA). We have previously shown that Abeta-induced inflammasome activation in RPE requires the RAGE-Rac-1 axis. Rac-1 is a small g protein largely regulated by farnesylation. In this study we wanted to investigate the effects of the farnesyl transferase inhibitor FTI-277 on A-beta-induced inflammasome activation in human retinal pigmented epithelial cells (ARPE19).
ARPE19 were stimulated for 48 and 72 hours with 5μM of Abeta 1-42 oligomers and the control reverse peptide (42-1). Some cells were contemporaneously treated with Abeta and with 25μM FTI-277. Western blotting and immunoprecipitation analyses were conducted to assess expression and protein-protein interaction of RAGE, toll-like receptor 4 (TLR4), NLRP3 and ASC. Caspase 1 activity was measured by an assay that detects the activity of caspases that recognize the YVAD sequence using a colorimetric method. ELISA assay was performed to measure IL-1beta production. Rac-1 activity was measured by assessing translocaton to the nuclear membrane and persistence of the Rac-1/GTP (active) complex.
Abeta stimulation of ARPE19 resulted in increased expression of RAGE and Rac-1 activation, as shown by its translocation to the plasma membrane and increased Rac-1/GTP ratio. Abeta treatments also prompted the expression and protein-protein interaction of NLRP3 and ASC proteins which was accompanied by increased TLR4 expression, caspase 1 activity and IL-1beta production. Treatments of ARPE19 with FTI-277 inhibited the A-beta effects on Rac-1/GTP complex. Moreover, FTI-277 prevented Abeta-induced increases in TLR4, and NLRP3 and promoted NLRP3/ASC interaction. FTI-277 also blunted Abeta-induced caspase-1 activity and production of IL-1beta.
The present studies demonstrate the efficacy of FTI-277 in preventing Abeta-induced inflammasome activation in RPE cells, a process which has been implicated in the induction and progression of AMD. Thus, the obtained results suggest the use of FTI-277 and/or other farnesyl transferase inhibitors as potential therapies for GA and AMD.
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