Figure 3. Xaliproden protects against the loss of tight junctions caused by oxidative stress and inflammation. ARPE-19 cells were grown for 4 weeks in low serum media until a change in the cuboidal shape was noticeable. They were then treated with 300 μM paraquat alone or in combination with xaliproden (20 μM) or left untreated for 48 h. Alternatively, the cells were treated with tumor necrosis factor-α (TNF-α; 10 ng/ml) or a combination of TNF-α and xaliproden for 48 h. Cultures were then permeabilized with 1% Triton X-100 and incubated with an antibody to zona occludens-1 (ZO-1), followed by a Cy-3 conjugated secondary antibody and viewed in a fluorescence microscope. A: Paraquat alone. B: Paraquat plus xaliproden. C: TNF-α alone. D: TNF-α plus xaliproden.