Heterogeneous activation thresholds to cytokines in genetically distinct endothelial cells: evidence for diverse transcriptional responses.
It is well accepted that the induction of endothelial cell (EC) adhesion molecules is a critical component in acute inflammatory responses as well as allogeneic interactions in vascularized allografts and, possibly, atherogenesis. The "inflammatory triad" of interleukin 1 (IL-1), tumor necrosis factor, and lipopolysaccharide are potent stimulators of the EC activation/adhesion molecules intercellular adhesion molecule 1 (ICAM-1), endothelial-leukocyte adhesion molecule 1 (ELAM-1), and vascular cell adhesion molecule 1 (VCAM-1). To address whether there exist differing thresholds to cytokine-mediated EC activation, we utilized a panel of genetically distinct human umbilical vein EC lines, assessing their modulated EC surface expression and transcriptional responses to cytokines, with regard to the cell adhesion molecules (CAMs) ELAM-1, ICAM-1, and VCAM-1. With submaximal concentrations of cytokine, EC ELAM-1 surface expression varied from negligible to marked. This phenotypic response was maintained over numerous passages in culture and was observed in ex vivo organ culture analyses with cytokine-treated umbilical vein sections. Relative patterns of ELAM-1, ICAM-1, and VCAM-1 induction were similar in response to multiple stimuli (IL-1, tumor necrosis factor, and lipopolysaccharide, but not phorbol 12-myristate 13-acetate). Nuclear run-off experiments demonstrated that the "high responder" phenotype is a consequence of enhanced transcriptional activation of the CAM genes in response to IL-1 (1 unit/ml), whereas transcriptional responses in "low responders" are minimal. Despite the known involvement of NF-kappa B in endothelial CAM transcription, gel shift assays failed to demonstrate a correlation between the levels of IL-1-mediated nuclear NF-kappa B expression and CAM induction in high and low responding lines. We postulate that varying EC activation thresholds to cytokines observed here, in vitro, may be a critical determinant in the susceptibility to vasculopathic states.
Bender
J R
JR
Boyer Center for Molecular Medicine, Cardiovascular Medicine, Yale University School of Medicine, New Haven, CT 06536-0812.
Sadeghi
M M
MM
Watson
C
C
Pfau
S
S
Pardi
R
R
D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D017931:DNA Primers / Q000737:chemistry; D019040:E-Selectin; D004730:Endothelium, Vascular / Q000166:cytology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D009924:Organ Culture Techniques; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
D015815:Cell Adhesion Molecules; D016207:Cytokines; D017931:DNA Primers; D019040:E-Selectin; D016328:NF-kappa B; D012333:RNA, Messenger