The platelet-endothelium interaction mediated by lectin-like oxidized low-density lipoprotein receptor-1 reduces the intracellular concentration of nitric oxide in endothelial cells.
OBJECTIVE
To address the potential role of the endothelial lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in the thrombotic system, in this study we first examined whether platelet interaction with LOX-1 generated reactive oxygen species (ROS) and superoxide (O2.-) and then investigated the relationship between the intracellular production of O2.- and the availability of nitric oxide (NO).


BACKGROUND
Oxidative inactivation of NO is regarded as an important cause of its decreased biologic activity which may favor platelet-dependent arterial thrombosis.


METHODS
Bovine aortic endothelial cells (BAECs) and Chinese hamster ovary-K1 cells stably expressing bovine LOX-1 (BLOX-1-CHO) were incubated at different times with human platelets. The ROS, O2.-, and NO were measured in cells by flow cytometry.


RESULTS
The incubation of BAECs and BLOX-1-CHO cells with human platelets induced a sharp and dose-dependent increase in intracellular concentration of ROS and O2.- (p from <0.01 to <0.001). The increase in intracellular concentration of O2.- was followed by a dose-dependent reduction in basal and bradykinin-induced intracellular NO concentration (p from <0.01 to <0.001). The increase in O2.- and the reduction of NO were inhibited by the presence of vitamin C and anti-LOX-1 monoclonal antibody (p < 0.001).


CONCLUSIONS
The results of this study show that one of the pathophysiologic consequences of platelet binding to LOX-1 may be the inactivation of NO through an increased cellular production of O2.-.
Cominacini
Luciano
L
Department of Biomedical and Surgical Sciences (Medicina D), University of Verona, Ospedale Policlinico, 37134 Verona, Italy. comina@medicinad.univr.it
Fratta Pasini
Anna
A
Garbin
Ulisse
U
Pastorino
Antonio
A
Rigoni
Anna
A
Nava
Cristina
C
Davoli
Anna
A
Lo Cascio
Vincenzo
V
Sawamura
Tatsuya
T
D000818:Animals; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology*; D002417:Cattle; D006224:Cricetinae; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology*; D005434:Flow Cytometry; D016166:Free Radical Scavengers / Q000032:analysis*; D006801:Humans; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000737:chemistry / Q000187:drug effects; D009569:Nitric Oxide / Q000032:analysis*; D016877:Oxidants / Q000032:analysis*; D017382:Reactive Oxygen Species / Q000032:analysis*; D011973:Receptors, LDL / Q000502:physiology*; D051131:Receptors, Oxidized LDL; D051127:Scavenger Receptors, Class E; D013481:Superoxides / Q000032:analysis*; D013927:Thrombosis / Q000503:physiopathology*
D016166:Free Radical Scavengers; C495137:OLR1 protein, human; D016877:Oxidants; D017382:Reactive Oxygen Species; D011973:Receptors, LDL; D051131:Receptors, Oxidized LDL; D051127:Scavenger Receptors, Class E; D013481:Superoxides; D009569:Nitric Oxide