Fibrinogen regulates the expression of inflammatory chemokines through NF-kappaB activation of endothelial cells.
The objective of this study was to characterize the role of fibrinogen in stimulating expression of inflammatory chemokines in endothelial cells through NF-kappaB activation. Human umbilical vein endothelial cells (HUVEC) were exposed to fibrinogen up to 3,000 microg/ml, and NF-kappaB activation was assessed using electrophoretic mobility shift assay (EMSA). Fibrinogen exposure resulted in a concentration dependent increase in NF-kappaB activation that reached a maximum at 1,000 microg/ml after 4 hours and was sustained up to 24 hours. The effect was inhibited by antibodies to alpha(v)beta(3) and alpha(5)beta(1) and by the GRGDS peptide, indicating integrin involvement. Preincubation with Mn(2+) lowered the fibrinogen concentration-dependence, consistent with integrin activation. Supershift assays demonstrated involvement of the p50, p65 and c-Rel components of NF-kappaB. Fibrinogen exposure also resulted in up-regulation of expression of monocyte chemoattractant protein-1 (MCP-1) and of interleukin-8 as shown by RNase protection assays and by real-time RT-PCR. Increased secretion of MCP-1 was confirmed by ELISA. Parthenolide, an IkappaB kinase inhibitor, prevented up-regulation of MCP-1 by fibrinogen, linking this response to NF-kappaB activation. From our findings, we conclude that fibrinogen regulates NF-kappaB activation and expression of inflammatory chemokines in endothelial cells and may be involved in mediating inflammatory processes.
Hematology-Oncology Unit, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
Min
M
Guo
Sanjeev K
SK
Sahni
Abha
A
Sahni
Charles W
CW
Francis
D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D018925:Chemokines / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D005340:Fibrinogen / Q000494:pharmacology / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007249:Inflammation / Q000235:genetics; D016023:Integrins / Q000502:physiology; D016209:Interleukin-8 / Q000235:genetics; D016328:NF-kappa B / Q000502:physiology*; D014471:Umbilical Veins / Q000166:cytology; D015854:Up-Regulation
C111835:CCL2 protein, human; D018932:Chemokine CCL2; D018925:Chemokines; D016023:Integrins; D016209:Interleukin-8; D016328:NF-kappa B; D005340:Fibrinogen