The tumour necrosis factor-alpha induced vascular permeability is associated with a reduction of VE-cadherin expression.

BACKGROUND: Vascular permeability is controlled by endothelial cell-to-cell junctions. Vascular endothelial (VE)-cadherin, the major component of adherence junctions (AJ) in the endothelium, is the target of the permeability-increasing agent tumour necrosis factor-a (TNF-alpha). We investigated whether TNF-alpha regulates the synthesis of VE-cadherin on the transcriptional level.
MATERIALS AND METHODS: Human endothelial cells, isolated from aorta (aEC) and umbilical cord (HUVEC), were exposed to TNF-alpha (200 U/ml) for 6 h or 12 h, with and without subsequent incubation with TNF-alpha for 24 h. VE-cadherin mRNA was evaluated by semi-quantitative RT-PCR. The VE-Cadherin protein expression was analyzed by flow cytometry (FACS).
RESULTS: The VE-cadherin amplification curve of TNF-alpha treated cells was shifted to the right compared to controls, indicating a lower mRNA amount. The number of cycles at which half-maximal amplification (N50) was achieved, was lower for control aEC (30.7) than for TNF-alpha treated aEC (33.0). The N50 of HUVEC treated with TNF-alpha for 12 h and 12 h + 24 h medium (N50 = 32.1), was higher compared to controls (N50 = 29.7) and cells treated with TNF-alpha for 6 h (N50 = 30.8). As determined by FACS analysis, incubation with TNF-alpha caused a small decrease of VE-cadherin protein expression from 7.44 to 6.05 mean channel intensity.
CONCLUSION: Our results indicate that TNF-alpha affects VE-cadherin gene expression on the transcriptional level, inducing a downregulation of the VE-cadherin expression.