Fig. 1

Blue light reduces CLDN5 protein level, destroys tight junction (TJ), and impairs the physiology barrier function of endothelial cells. A The bEnd.3 and HREC monolayer were exposed to blue light (80, 160, and 240 lx) for 12 h, followed by routine immunoblotting. Representative images and histograms showed an obvious CLDN5 protein downregulation in illuminance-dependent manner. B CLDN5 protein began to degrade upon 3–6 h, 160 lx blue light exposure. The expression level of TJP1 and OCLN remained unaltered. (*p < 0.05, ***p < 0.001, indicates statistical difference from the control treatment). C TEM images showed a clear TJ ultrastructure in the border of adjacent bEnd.3 cells. After 12 h and 160 lx blue light exposure, the TJ almost disappeared, and an obvious cleft between adjacent cells was observed. The N represents the nucleus. D The CLDN5-positive strands that appeared at the border of HREC membrane became discontinuous under blue light, suggesting that TJs were damaged. E TEER values were measured as described in Materials and Methods to evaluate the barrier function. TEER value across the bEnd.3 cell and HREC monolayer was notably reduced with time after 160 lx blue light exposure (***p < 0.001, indicates statistical difference from the control). These data supported the loss of the physiology barrier in blue-light-treated endothelial cells