Endothelial cell activation by IL-1beta in the presence of fibrinogen requires alphavbeta3.
OBJECTIVE
The purpose of this study was to investigate the receptor requirements for enhanced IL-1beta-induced secretion of nitric oxide (NO) by endothelial cells (ECs) in the presence of fibrinogen.


RESULTS
ECs were exposed to IL-1beta with or without fibrinogen and NO was measured as nitrite. NO production by EC exposed to fibrinogen (0.3+/-0.1 micromol/L) was comparable concentration to control (0.2+/-0.1 micromol/L), but IL-1beta significantly increased NO production (0.8+/-0.1 micromol/L), and the combination of both fibrinogen and IL-1beta resulted in a further increase to 2.2+/-0.2 micromol/L (P<0.002). 7E3 or LM609, antibodies to alphavbeta3, inhibited NO production stimulated by fibrinogen-bound IL-1beta to 0.2+/-0.1 micromol/L (P<0.001) or 0.2+/-0.03 micromol/L (P<0.0001), respectively. These levels were comparable to control and significantly less than with IL-1beta (P<0.002). EC or fibroblasts exposed to both fibrinogen and IL-1beta, but not vitronectin and IL-1beta, demonstrated positive Western blotting for alphavbeta3 after immunopurification with anti- IL-1R, indicating specific association between alphavbeta3 and IL-1R. Dual immunofluorescence also revealed colocalization of alphavbeta3 and IL-1R only when the cells were exposed to both fibrinogen and IL-1beta.


CONCLUSIONS
The enhanced NO production by ECs in the presence of fibrinogen-bound IL-1beta requires the coordinated effects of colocalized alphavbeta3 and IL-1R.
Sahni
Abha
A
Department of Medicine, University of Rochester School of Medicine & Dentistry, Rochester, NY, USA. Abha_Sahni@urmc.rochester.edu
Sahni
Sanjeev K
SK
Francis
Charles W
CW
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002478:Cells, Cultured; D004347:Drug Interactions; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000276:immunology / Q000378:metabolism*; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D039341:Receptors, Fibrinogen / Q000276:immunology / Q000378:metabolism*; D017472:Receptors, Interleukin-1 / Q000276:immunology / Q000378:metabolism; D013927:Thrombosis / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology
D000911:Antibodies, Monoclonal; D039302:Integrin alphaVbeta3; D007375:Interleukin-1; D039341:Receptors, Fibrinogen; D017472:Receptors, Interleukin-1; D009569:Nitric Oxide; D005340:Fibrinogen; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III