TA attenuated monocyte adhesion to ECs. (A,B) HCAECs were pretreated with vehicle (DMSO) or TA (10.0 µM) for 12 h, and then exposed to TNFα (10 ng/ml) or vehicle (PBS) for an additional 6 h. Then, THP-1 monocytes were added for 30 min. (A) Images were taken from representative optical fields showing endothelial cells (cobblestone shape) and adhering THP-1 monocytes (small, round cells) in the co-culture. (B) THP-1 cells in panel A were counted and statistically analyzed. *p < 0.05, **p < 0.01, n = 4. (C–E) HUVECs were transfected with siRNA (control siRNA) or siKLF2 (KLF2 siRNA) for 48 h. Then the cells were pretreated vehicle (DMSO) or TA (10.0 µM) for 12 h, and then exposed to TNFα (10 ng/ml) or vehicle (PBS) for an additional 6 h. Then, THP-1 monocytes were added for 30 min. (C) The levels of KLF2 mRNA in ECs treated with control siRNA and KLF2 siRNA were analyzed by q-PCR. (D) Images were taken from representative optical fields showing endothelial cells (cobblestone shape) and adhering THP-1 monocytes (small, round cells) in the co-culture. (E) THP-1 cells in panel C were counted and statistically analyzed. One way ANOVA was used to analyze the data. *p < 0.05, **p < 0.01, n = 3.