Received on December 16, 2005
Accepted on July 10, 2006

Drug Monitoring and Toxicology

Cocaethylene Affects Human Microvascular Endothelial Cell p38 Mitogen-Activated Protein Kinase Activation and Nuclear Factor-B DNA-Binding Activity

¹ Department of Pathology, University of Texas Medical Branch, Galveston, TX

Background: Cocaethylene (CE) is known to increase the permeability of human microvascular endothelial cell monolayers. The molecular mechanism underlying this increase may involve calcium-modulated signaling pathways such as the p38 mitogen-activated protein kinase (p38 MAPK) and the nuclear factor-B (NF-B) family of transcription factors. The hypothesis of this study was that CE-mediated endothelial permeability change may be mediated by the p38 MAPK and consequently NF-B dimers.

Methods: We used sandwich ELISA to detect phosphorylated p38 MAPK in the cell line human microvascular endothelial cell 1 (HMEC-1) after treatment with 1 mmol/L CE. We used electrophoretic mobility shift assay to detect changes in NF-B dimers present in HMEC-1 and their DNA-binding activity after treatment with CE. Lipopolysaccharide (LPS) from Salmonella typhosa was used as a positive control for all experiments.

Results: Treatment with CE and LPS had similar effects on HMEC-1 p38 MAPK phosphorylation and NF-B DNA-binding activity. Both treatments increased the phosphorylation of p38 MAPK, consistent with activation of proinflammatory cell signaling. Treatment of HMEC-1 with CE decreased DNA binding of both the RelA/p50 and p50/p50 dimers of the NF-B transcription factor family, whereas treatment with LPS decreased and then increased the DNA binding of these dimers.

Conclusion: In addition to increasing HMEC-1 monolayer permeability, CE also alters transcription factor and kinase activity related to inflammation. Thus, CE causes endothelial activation that can elicit a prolonged and organized cellular response, rather than being directly toxic to endothelial cells.