Human monoclonal IgG anticardiolipin antibodies induce nitric oxide synthase expression.
OBJECTIVE
Antiphospholipid antibodies are associated with increased risk of thrombosis, particularly as in antiphospholipid syndrome. This study aims to determine the acute effects of anticardiolipin antibodies on nitric oxide production and vascular function.


METHODS
Ex vivo aortic rings from male Sprague Dawley rats were incubated with IgG monoclonal anticardiolipin antibody (IS4) or a non-specific IgG control. In organ baths, response to phenylephrine and acetlycholine was determined alone and with nitro-L-arginine methyl ester (L-NAME), 1,400 W, D-arginine, L-arginine, sodium nitroprusside and cardiolipin. In vivo antibodies were injected into anaesthetised, spontaneously breathing male Sprague Dawley rats. Haemodynamic variables and serum nitric oxide were measured. Immunohistochemistry for iNOS and eNOS was performed in kidney vessels.


RESULTS
Phenylepherine contraction was decreased in the IS4 group compared to controls (p < 0.001). L-NAME, 1,400 W and cardiolipin, abolished this effect. L-Arginine caused significant relaxation in the IS4 group (p = 0.005). Mean arterial pressure in rats injected with IS4 was reduced compared to IgG and saline controls (p < 0.001). NO in plasma increased significantly after IS4 administration (p < 0.001). Immunohistochemistry showed increased iNOS expression in kidney arteries in the IS4 group, with no change in eNOS.


CONCLUSIONS
Anticardiolipin antibodies induce NO production acutely via increased expression of iNOS in both ex vivo and in vivo models.
Alves
J Delgado
JD
Department of Pharmacology, Faculty of Medical Sciences, New University of Lisbon, Campo Mártires da Pátria 130, 1169-056 Lisboa, Portugal.
Clapp
B R
BR
Stidwill
R
R
Chen
P P
PP
Hingorani
A D
AD
Singer
M
M
Isenberg
D A
DA
D000818:Animals; D017153:Antibodies, Anticardiolipin / Q000276:immunology / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001011:Aorta / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000097:blood; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012077:Renal Artery / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D017153:Antibodies, Anticardiolipin; D000911:Antibodies, Monoclonal; D004791:Enzyme Inhibitors; D007074:Immunoglobulin G; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D019331:NG-Nitroarginine Methyl Ester