CLDN5 and diabetes mellitus: Treatment of diabetic rats with TNFSF15 prevented the decrease in claudin-5, occludin, and ZO-1 protein levels caused by diabetes (95.8% ± 10.6%, 85.4% ± 9.2% and 94.1% ± 11.7% of the control, respectively), indicating that TNFSF15 mediates the expression of TJPs (Figure 5B,C).