Heme induces the expression of adhesion molecules ICAM-1, VCAM-1, and E selectin in vascular endothelial cells.
Heme is an important immunostimulating agent and oxidative factor contributing to endothelial cell activation. To investigate the mechanism of heme-induced endothelial cell activation, we analyzed the effect of heme and the inflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), on the expression of the heme-degrading stress protein, heme oxygenase (HO), and adhesion molecules in human umbilical vein endothelial cells (HUVEC). Indirect immunofluorescence double labeling studies demonstrated a simultaneous increase of ICAM-1 and HO-1 after exposure of cells to heme for 24 hr. Co-expression of HO-1 and ICAM-1 was also demonstrated in TNF-alpha-exposed cells. Dot blot immunoassay and quantitative analysis by ELISA demonstrated that heme treatment for 24 hr caused a 2-fold increase in ICAM-1 expression (P < 0.002) compared with quiescent cells, while in cells stimulated by TNF-alpha for 24 hr ICAM-1 gene expression increased by 5-fold. Moreover, heme exposure also resulted in a marked increase in VCAM-1 and E selectin expression (three and four times over control levels, respectively). On the other hand, TNF-alpha treatment showed similar expression levels for VCAM-1 and E selectin, compared with stimulation by heme (100 microM). The level of HO activity in endothelial cells exposed to heme or TNF-alpha was increased from 24.7 +/- 5.7 pmol bilirubin/mg protein/min in control to 70.0 +/- 9.5 and 36.7 +/- 3.1 pmol bilirubin/mg protein/min in heme- and TNF-alpha-stimulated cells, respectively. These results suggest that upregulation of ICAM-1, VCAM-1, and E selectin expression is associated with oxidative stress induced by hemoglobin/heme and that HO-1 may play a modulating role via its ability to degrade heme to a substance with antioxidant properties.
Wagener
F A
FA
Department of Pharmacology, New York Medical College, Valhalla 10595, USA.
Feldman
E
E
de Witte
T
T
Abraham
N G
NG
D015815:Cell Adhesion Molecules / Q000032:analysis / Q000096:biosynthesis* / Q000187:drug effects*; D019040:E-Selectin / Q000096:biosynthesis / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D006418:Heme / Q000494:pharmacology*; D006419:Heme Oxygenase (Decyclizing) / Q000032:analysis / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis / Q000096:biosynthesis / Q000187:drug effects; D008163:Luminescent Measurements; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis / Q000187:drug effects
D015815:Cell Adhesion Molecules; D019040:E-Selectin; D008565:Membrane Proteins; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D006418:Heme; D006419:Heme Oxygenase (Decyclizing)