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. 2013 Jun 28;8(6):e67263. doi: 10.1371/journal.pone.0067263

Figure 4. Effect of cathepsin-B inhibition on IL-1ß production by ARPE-19 cells following exposure to A2E.

Figure 4

Undifferentiated ARPE-19 cells were pre-stimulated for 48 hours with 1000 pg/ml IL-1α. During the last 24 hours of pre-stimulation, 0, 10 or 20 µM of cathepsin-B inhibitor was added. The medium was then exchanged for serum free DMEM containing 10 µM A2E, along with the cathepsin-B inhibitor (at the same concentration as during the preceding pre-stimulation step). After 24 hours the cell culture supernatant was collected and processed using ELISA. Cathepsin-B inhibitor stock was dissolved in DMSO. Therefore DMSO at the same concentration, but without cathepsin-B inhibitor, was used as a negative control. The effect of cathepsin-B inhibition on ATP (20 µM) induced IL-1ß production was also assessed. Eight separate wells were stimulated with each concentration (n  = 8). Error bars represent standard deviation. (*) 20 µM of Cathepsin-B inhibitor significantly inhibited IL-1ß production as compared to the DMSO control (p<0.0001, one-way ANOVA).