Toll-like receptor and antiphospholipid mediated thrombosis: in vivo studies.
OBJECTIVE
A study was undertaken to investigate the in vivo pathogenic role of Toll-like receptor 4 (TLR-4) in the antiphospholipid syndrome (APS) by studying the thrombogenic antiphospholipid (aPL) activity in lipopolysaccharide (LPS) non-responsive (LPS-/-) mice and the association between tlr4 gene polymorphisms and APS in patients.


METHODS
IgGs from two patients with APS, one with aPL negative systemic lupus erythematosus (SLE) and one with normal human serum (NHS), were evaluated for thrombosis, tissue factor (TF) activity and endothelial cell activation in LPS-/- mice displaying a tlr4 spontaneous mutation vs LPS responsive (LPS+/+) mice. Human tlr4 Asp299Gly and Thr399Ile polymorphisms were evaluated by allele-specific PCR in 110 patients with APS with arterial/venous thrombosis and in 220 controls of the same ethnic origin.


RESULTS
IgG-APS produced significantly larger thrombi and more leucocytes (WBC) adhering to endothelial cells in the cremaster muscle microcirculation of LPS+/+ mice than IgG-NHS or aPL negative SLE-IgG. These effects were abrogated after absorption of the anti-beta(2)glycoprotein I activity by an affinity column. The two IgG-APS induced significantly smaller thrombi and fewer WBC adhering to endothelial cells in LPS-/- mice than in LPS+/+ mice. IgG-APS induced higher TF activity in carotid artery homogenates of LPS+/+ mice than in LPS-/- mice. The prevalence of Asp299Gly and Thr399Ile tlr4 polymorphisms was significantly lower than in controls.


CONCLUSIONS
These findings in LPS-/- mice and the reduction in the "protective" polymorphism in patients with APS with thrombosis suggest that TLR-4 is involved in the interaction of aPL with endothelial cells in vivo.
Pierangeli
Silvia S
SS
Antiphospholipid Standardization Laboratory, Division of Rheumatology, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555-1165, USA. sspieran@utmb.edu
Vega-Ostertag
Mariano E
ME
Raschi
Elena
E
Liu
Xiaowei
X
Romay-Penabad
Zurina
Z
De Micheli
Valeria
V
Galli
Monica
M
Moia
Marco
M
Tincani
Angela
A
Borghi
Maria Orietta
MO
Nguyen-Oghalai
Tracy
T
Meroni
Pier Luigi
PL
D000328:Adult; D000818:Animals; D017153:Antibodies, Anticardiolipin / Q000276:immunology; D017152:Antibodies, Antiphospholipid / Q000276:immunology; D000925:Anticoagulants / Q000276:immunology; D016736:Antiphospholipid Syndrome / Q000150:complications / Q000276:immunology*; D002448:Cell Adhesion / Q000276:immunology; D042783:Endothelial Cells / Q000276:immunology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007962:Leukocytes / Q000276:immunology; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D011110:Polymorphism, Genetic / Q000235:genetics; D019851:Thrombophilia / Q000276:immunology; D013925:Thromboplastin / Q000276:immunology; D013927:Thrombosis / Q000150:complications / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology*; D053482:beta 2-Glycoprotein I / Q000276:immunology
D017153:Antibodies, Anticardiolipin; D017152:Antibodies, Antiphospholipid; D000925:Anticoagulants; D007074:Immunoglobulin G; D051197:Toll-Like Receptor 4; D053482:beta 2-Glycoprotein I; D013925:Thromboplastin