Antiphospholipid antibodies, thrombin and LPS activate brain endothelial cells and Ras-dependent pathways through distinct mechanisms.
BACKGROUND
The antiphospholipid syndrome (APS) commonly affects the central nervous system through mechanisms that may include small vessel pathology and activation of thrombin. Antiphospholipid antibodies (aPL) activate endothelial cells but the specific activation of brain vascular endothelial cells (BVEC) and the receptors and signaling pathways involved have not been fully characterized.


OBJECTIVE
To examine whether aPL, the inflammatory stimulant lipopolysacharide (LPS) and thrombin activate BVECs through a Ras-dependent pathway.


METHODS
Rat BVEC (G8) were grown to confluence on 24-well plates. IgG was purified from 8 APS patients on a protein G column. Phosphorylation of ERK in the BVEC was measured by immunoblot utilizing a specific antibody.


RESULTS
Significant phosphorylation of ERK was measured following exposure of the cells to LPS and thrombin and this was blocked by the Ras inhibitor farnesylthiosalicylate (FTS). aPL IgG (1:100 relative to serum) from 7/8 patients also induced phosphorylation of ERK.


CONCLUSIONS
Activation of the Ras-ERK pathway is an effect of both APS IgG and thrombin. This pathway is potentially amenable to drugs such as FTS and may serve as a therapeutic target in APS.
Aronovich
Ramona
R
Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel.
Gurwitz
David
D
Kloog
Yoel
Y
Chapman
Joab
J
D000818:Animals; D017152:Antibodies, Antiphospholipid / Q000494:pharmacology*; D016736:Antiphospholipid Syndrome / Q000276:immunology; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005204:Farnesol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D012459:Salicylates / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology*; D018631:ras Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*
D017152:Antibodies, Antiphospholipid; D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D012459:Salicylates; C093323:farnesylthiosalicylic acid; D018799:Intercellular Adhesion Molecule-1; D005204:Farnesol; D048049:Extracellular Signal-Regulated MAP Kinases; D013917:Thrombin; D018631:ras Proteins