ADI-PEG20 treatment reduces retinal inflammation and improves blood-retinal barrier function in db/db retinas. Representative western blot and quantitation of TNF-α (A, B), IL-1β (C, D), and iNOS (E, F) in retina protein lysate after 4 and 12 weeks of treatment (n = 6–10/group). Representative western blots and quantitation of extravasated albumin (G, H) in retina protein lysate after 4 and 12 weeks of treatment (n = 8–10/group). ns = not significant, ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.005, ∗∗∗∗p < 0.0001.