title: Arachidonic acid metabolites are involved in mediating red blood cell adherence to endothelium.
abstract: As an initial investigation into the possible role of endothelial cell (EC) lipoxygenase and cyclooxygenase metabolites in the adherence of red blood cells (RBCs) to ECs, we evaluated the effect of nordihydroguaiaretic acid, (NDGA; 10 mumols/L, BW755c (30 mumols/L), aspirin (100 mumols/L), and indomethacin (10 mumols/L) on RBC-EC adherence using a static incubation system and 51Cr-labeled RBCs. NDGA and 3-amino-L-[3'-(trifluoromethyl)phenyl]-2-pyrazoline inhibitors of both the lipoxygenase and cyclooxygenase pathways, significantly decreased basal adhesion of RBCs to fetal bovine aortic ECs, whereas aspirin and indomethacin, selective inhibitors of the cyclooxygenase pathway, stimulated the adherence process. The inhibitor effect appeared to be mediated via an effect on EC functions, since preincubation of ECs with NDGA, in contrast to RBC-NDGA preincubation, inhibited the adherence process. Because bovine aortic ECs generate mainly prostacyclin and 15-HETE from arachidonic acid (AA) via the cyclooxygenase and the lipoxygenase pathways respectively, the role of these products (100 pmol/L to 1 mumol/L) on the adhesive process was further assessed. 15-HETE potentiated basal adhesion of RBCs to bovine aortic ECs in a concentration-dependent manner, with maximal responses of approximately 50% to 150% over baseline noted at concentrations between 1 and 100 nmol/L 12-HETE, a structural isomer of 15-HETE and the major platelet lipoxygenase product, also stimulated RBC adherence. In contrast, prostacyclin (assessed using carbacyclin, a stable synthetic analog of prostacyclin with similar biologic properties) had no significant effect on this process. In further studies, we demonstrated that the 12-HETE-induced adherence of sickle RBCs was mediated via an up-regulation of the vitronectin receptor on bovine aortic endothelium. Because microvascular capillary endothelium is the surface most likely to encounter erythrocytes in vivo, we extended our studies to human retinal capillary ECs to assess the involvement of eicosanoids in sickle RBC-microvessel adhesion. As with bovine aortic ECs, aspirin stimulated and NDGA decreased the adherence of sickle RBCs to human retinal capillary endothelium. These microvascular ECs generated prostacyclin, HHT, 15-HETE, and 15-HPETE from endogenous AA. Although carbacyclin and HHT had no effect on the adherence process, both 15-HETE and 15-HPETE (10 pmol/L to 100 nmol/L) stimulated RBC adhesion to capillary endothelium. Our studies document a role for the lipoxygenase metabolites in modulating basal adhesion of RBCs to both macrovascular and microvascular endothelium; the major cyclooxygenase metabolites appear to play no role in this process.
authors.affiliation: Division of Pediatric Hematology-Oncology, St. Christopher's Hospital for Children, Philadelphia, PA 19134-1095, USA.
authors.forename: B N
authors.initials: BN
authors.lastname: Setty
authors.forename: C D
authors.initials: CD
authors.lastname: Dampier
authors.forename: M J
authors.initials: MJ
authors.lastname: Stuart
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects; D016718:Arachidonic Acid / Q000378:metabolism*; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015777:Eicosanoids / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D004912:Erythrocytes / Q000502:physiology*; D006801:Humans; D016023:Integrins / Q000187:drug effects / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008833:Microcirculation / Q000187:drug effects; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D016024:Receptors, Cytoadhesin / Q000187:drug effects / Q000378:metabolism; D019030:Receptors, Vitronectin
chemical_list: D016861:Cyclooxygenase Inhibitors; D015777:Eicosanoids; D016023:Integrins; D016859:Lipoxygenase Inhibitors; D010980:Platelet Membrane Glycoproteins; D016024:Receptors, Cytoadhesin; D019030:Receptors, Vitronectin; D016718:Arachidonic Acid