title: Endothelial activation and induction of monocyte adhesion by nontransferrin-bound iron present in human sera.
abstract: Nontransferrin-bound iron (NTBI) has been detected in iron overload diseases. This form of iron may exert pro-oxidant effects and modulate cellular function and inflammatory response. The present study has aimed to investigate the effects of serum NTBI on monocyte adherence to endothelium. Measured by a recently developed high-throughput fluorescence-based assay, serum NTBI was found to be higher in both homozygotes of HFE C282Y mutation of hereditary hemochromatosis (7.9+/-0.6 microM, n=9, P<0.001) and heterozygotes (4.0+/-0.5 microM, n=8, P<0.001), compared with controls (1.6+/-0.2 microM, n=21). The effects of these sera on monocyte adhesion and endothelial activation were examined. Adhesion of normal human monocytes to C282Y homozygote- and heterozygote-serum-treated human umbilical vein endothelial cells was higher (25.0+/-0.9 and 22.1+/-0.7%, respectively) compared with controls (17.6+/-0.5%, both P<0.001). For the three groups combined, the expression of adhesion molecules, ICAM-1, VCAM-1, and E-selectin, was positively correlated to NTBI levels but not to the inflammatory marker C-reactive protein. Furthermore, accumulation of intracellular labile iron and oxidative radicals within the cells due to NTBI was evidenced. Finally, counteraction of NTBI-induced endothelial activation was observed using iron chelators. These findings therefore identify a physiological function of NTBI in monocyte-endothelial interactions that may also contribute to the development of atherosclerosis and neurodegenerative diseases.
authors.affiliation: Eijkman-Winkler Center for Medical Microbiology, Infectious Diseases and Inflammation, University Medical Center Utrecht, 100 Heidelberglaan, G04.614, Utrecht 3584CX, The Netherlands. jmarx@azu.nl.
authors.forename: Apriliana E R
authors.initials: AE
authors.lastname: Kartikasari
authors.forename: Niki A
authors.initials: NA
authors.lastname: Georgiou
authors.forename: Frank L J
authors.initials: FL
authors.lastname: Visseren
authors.forename: Henny
authors.initials: H
authors.lastname: van Kats-Renaud
authors.forename: B Sweder
authors.initials: BS
authors.lastname: van Asbeck
authors.forename: Joannes J M
authors.initials: JJ
authors.lastname: Marx
mesh_terms: D002448:Cell Adhesion; D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D004727:Endothelium / Q000378:metabolism*; D000071020:Hemochromatosis Protein; D006579:Heterozygote; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism; D006720:Homozygote; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009000:Monocytes / Q000166:cytology*; D009154:Mutation; D011485:Protein Binding; D014168:Transferrin / Q000378:metabolism
chemical_list: C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D014168:Transferrin; D007501:Iron