LPS-induced hyperpermeability in brain vascular endothelial cell is related to NF-κB signaling

AIM: To investigate the role of nuclear factor kappa B (NF-κB) signaling in the changes of permeability in brain-derived microvascular endothelial (bEnd.3) cells induced by lipopolysaccharide (LPS).METHODS: The bEnd.3 cells were randomly divided into 3 groups: bEnd.3 group, bEnd.3/vector group and bEnd.3/muIκBα group. The cells in the latter 2 groups were transfected with pcDNA3.1hygro and DNMu-IκBα (a dominant-negative mutant of IκB) plasmids, respectively. All the cells were exposed to LPS. The activity of NF-κB, monolayer barrier integrity and F-actin distribution were detected by luciferase reporter assay, transendothelial electrical resistance (TEER) assay and rhodamine-phalloidin staining, respectively. The expression of tight junction proteins (ZO-1 and claudin-5) and phosphorylation of myosin light chain (MLC) were determined using Western blotting.RESULTS: In bEnd.3 group and bEnd.3/vector group, the NF-κB activity began to increase obviously as early as 0.5 h after pretreatment with LPS. LPS decreased TEER, and induced F-actin rearrangement and ZO-1 down-regulation in 3 h. Incubation of the cells with LPS for 12 h induced the most significant disruptive effects on the permeability and tight junctions. Moreover, high expression of phosphorylated MLC accompanied with the early damages of tight junctions was observed. However, these destabilizing alterations were suppressed in bEnd.3/muIκBα group by the inhibition of NF-κB activity.CONCLUSION: LPS induces hyperpermeability in brain microvascular endothelial cells. The functions of NF-κB signaling are related to influencing disruptions of tight junctions by regulating the phosphorylation of MLC.