title: 12/15-Lipoxygenase activity mediates inflammatory monocyte/endothelial interactions and atherosclerosis in vivo.
abstract: We have shown that the 12/15-lipoxygenase (12/15-LO) product 12S-hydroxyeicosatetraenoic acid increases monocyte adhesion to human endothelial cells (EC) in vitro. Recent studies have implicated 12/15-LO in mediating atherosclerosis in mice. We generated transgenic mice on a C57BL/6J (B6) background that modestly overexpressed the murine 12/15-LO gene (designated LOTG). LOTG mice had 2.5-fold elevations in levels of 12S-hydroxyeicosatetraenoic acid and a 2-fold increase in expression of 12/15-LO protein in vivo. These mice developed spontaneous aortic fatty streak lesions on a chow diet. Thus, we examined effects of 12/15-LO expression on early events leading to atherosclerosis in these mice. We found that, under basal unstimulated conditions, LOTG EC bound more monocytes than B6 control EC (18 +/- 2 versus 7 +/- 1 monocytes/field, respectively; p < 0.0001). Inhibition of 12/15-LO activity in LOTG EC using a 12/15-LO ribozyme completely blocked monocyte adhesion in LOTG mice. Thus, 12/15-LO activity is required for monocyte/EC adhesion in the vessel wall. Expression of ICAM-1 in aortic endothelia of LOTG mice was increased severalfold. VCAM-1 expression was not changed. In a series of blocking studies, antibodies to alpha(4) and beta(2) integrins in WEHI monocytes blocked monocyte adhesion to both LOTG and B6 control EC. Inhibition of ICAM-1, VCAM-1, and connecting segment-1 fibronectin in EC significantly reduced adhesion of WEHI monocytes to LOTG EC. In summary, these data indicate that EC from LOTG mice are "pre-activated" to bind monocytes. Monocyte adhesion in LOTG mice is mediated through beta(2) integrin and ICAM-1 interactions as well as through VLA-4 and connecting segment-1 fibronectin/VCAM-1 interactions. Thus, 12/15-LO mediates monocyte/EC interactions in the vessel wall in atherogenesis at least in part through molecular regulation of expression of endothelial adhesion molecules.
authors.affiliation: Department of Diabetes, Beckman Research Institute, City of Hope National Medical Center, Duarte, California 91010, USA.
authors.forename: Kelly B
authors.initials: KB
authors.lastname: Reilly
authors.forename: Suseela
authors.initials: S
authors.lastname: Srinivasan
authors.forename: Melissa E
authors.initials: ME
authors.lastname: Hatley
authors.forename: Mary Kim
authors.initials: MK
authors.lastname: Patricia
authors.forename: Joanne
authors.initials: J
authors.lastname: Lannigan
authors.forename: David T
authors.initials: DT
authors.lastname: Bolick
authors.forename: George
authors.initials: G
authors.lastname: Vandenhoff
authors.forename: Hong
authors.initials: H
authors.lastname: Pei
authors.forename: Rama
authors.initials: R
authors.lastname: Natarajan
authors.forename: Jerry L
authors.initials: JL
authors.lastname: Nadler
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Hedrick
mesh_terms: D000818:Animals; D001161:Arteriosclerosis / Q000201:enzymology* / Q000473:pathology; D002448:Cell Adhesion; D004730:Endothelium, Vascular / Q000201:enzymology / Q000473:pathology; D004789:Enzyme Activation; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008084:Lipoxygenase / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009000:Monocytes / Q000201:enzymology / Q000473:pathology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D008084:Lipoxygenase