Lipid presentation by the protein C receptor links coagulation with autoimmunity

A lipid-protein autoimmunity target Several autoimmune diseases, including systemic lupus erythematosus and primary antiphospholipid syndrome, are characterized by the presence of antiphospholipid antibodies (aPLs). These molecules can activate the complement and coagulation cascades, which contributes to pathologies such as thrombosis, stroke, and pregnancy complications. Müller-Calleja et al. found that endothelial protein C receptor (EPCR) in complex with lysobisphosphatidic acid (LBPA) is the cell-surface target for aPL and mediates its internalization (see the Perspective by Kaplan). aPL binding to EPCR-LBPA resulted in the activation of tissue factor–mediated coagulation and interferon-α production by dendritic cells. Interferon-α, in turn, fueled the expansion of B1a cells, which secrete aPLs. The specific blockade of this target in mice inhibited the development of aPL autoimmunity, offering hope for future therapies for these conditions. Science , this issue p. eaay1833 ; see also p. 1100