OCLN and diabetes mellitus: As expected, retinas of Akita mice 12 weeks after the onset of diabetes showed increased number of leukocytes adhered to blood vessels (Fig. 1A), downregulated expression of the tight junction proteins occludin and ZO-1 (Fig. 1B), and enhanced dextran leakage from vessels (Fig. 1C), compared with respect to those of WT mice.