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Hartmut Weiler
Published in Volume 118, Issue 10
J Clin Invest. 2008; 118(10):3276–3278 doi:10.1172/JCI37243
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Figure 1
Role of TF/PAR2 signaling in aPL-induced fetal loss.

Maternal aPLs activate the complement system in the placenta. Engagement of C5aR triggers expression by neutrophils of the blood coagulation initiator TF, resulting in generation of reactive oxygen species, injury to fetal trophoblast cells of the placenta, and ultimately loss of the fetus. TF binds and activates coagulation factors FVII and FX circulating in maternal blood to form the ternary TF/FVIIa/FXa complex. The study by Redecha et al. in this issue of the JCI (10) shows that TF-mediated neutrophil activation proceeds through engagement of PAR2 via this initiation complex of blood coagulation. The statin drugs simvastatin and pravastatin prevent C5a-induced upregulation of TF and PAR2 expression, thereby inhibiting the release of reactive oxygen species and suppressing amplification of complement activation by factors released from neutrophils. Statins may hold promise as a therapeutic approach to APS-associated pregnancy complications.