Effects of LPS, IL-6, and GM-CSF on the expression of tight junction proteins in BMECs. BMECs were exposed to LPS (100 μg/mL), IL-6 (100 ng/mL), or GM-CSF (100 ng/mL) for 4 hr. Expression levels of occludin, claudin-5, ZO-1, and actin were detected by western blot. Relative intensity of occludin (A), claudin-5 (B), and ZO-1 (C) is calculated as ratio of arbitrary densitometric units of target protein to that of actin. Results are expressed % of control. Values are means ± SEM (n = 3). (D) Photographs are representative in three independent experiments.