Libman-Sacks endocarditis associated with antiphospholipid syndrome and infection

M. Blank, A. Shani, I. Goldberg, J. Kopolovic, M. C. Amigo, L. Magrini, Y. Shoenfeld

Research output: Contribution to journalArticlepeer-review


Antiphospholipid syndrome (APS) is a systemic autoimmune disease, associated not only with a hypercoagulable state and recurrent fetal loss but with many diverse clinical manifestations including heart involvement, neurological manifestations, as well as skin, kidney and hematologic abnormalities. Cardiac manifestations include coronary by-pass graft and angioplasty occlusions, cardiomyopathy, cyanotic congenital heart disease, intracardiac thrombus and complications of cardiovascular surgery. The valvular heart disease was defined as Libman-Sacks nonbacterial endocarditis. Previously, we have shown a linear subendothelial deposition of anti-cardiolipin/ β 2 glycoprotein I (β2GPI) antibodies in the valve specimens derived from APS patients. The involvement of complement C3c in the pathogenesis was documented. We assessed the β2GPI-related target epitope recognized by the anti-β2GPI Abs on the valves. In order to find the β2GPI-related target epitopes recognized by the anti-β2GPI antibodies on the valves, we used β2GPI-related synthetic peptides. The presence of anti-β2GPI Abs on the studied valves was detected by anti-idiotypic antibody, followed by immunoperoxidase analysis. Biotin attached to the N-terminal of β2GPI-related synthetic peptides and control peptide were used to identify the epitope addressed by the anti-β2GPI Abs deposited on the patient's valve. The binding was probed by streptavidin-peroxidase and appropriate substrate. The specificity was confirmed by competition assays with control peptide and anti-idiotypic antibody. Among the β2GPI-related synthetic peptides, two peptides were found in previous studies to mimic common pathogens either bacteriae or viruses, which raised a possible infectious origin for APS. One of these peptides, TLRVYK, is a specific target for anti-β2GPI Abs deposited on the APS valves. This synthetic peptide was able to displace the anti-anti-β2GPI anti-idiotypic Abs for binding the anti-β2GPI Abs on the valve by a competition assay. We point to the possibility that Libman-Sacks nonbacterial endocarditis may have an infectious origin.

Original languageEnglish
Pages (from-to)589-592
Number of pages4
JournalThrombosis Research
Issue number5-6 SPEC. ISS.
StatePublished - 2004


  • Antiphospholipid syndrome
  • Beta-2-glycoprotein-I
  • Libman-Sacks endocarditis
  • Synthetic peptides


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