ABSTRACT
Antiphospholipid syndrome (APS) is characterized by thromboembolic phenomena and recurrent fetal loss associated with elevated circulating anti-phospholipid/beta2glycoprotein-I(ß2GPI)-binding-antibodies(Abs). Individual APS patients harbor diverse clusters of circulating anti-ß2GPI Abs, targeting different epitopes on the ß2GPI molecule. Our novel approach was to construct a peptide composed of ß2GPI-ECs-binding-site (phospholipids-membrane), named "EMBI". EMBI exert dual activities: a) At first EMBI prevented ß2GPI ECs binding, thus reduced by 89% the binding of ß2GPI/anti-ß2GPI to the cells in comparison with 9.3% inhibition by EMBI scrambled form (scEMBI). b) Longer exposure of ECs to EMBI resulted in intracellular EMBI penetration which did not prevent ß2GPI/anti-ß2GPI binding to HUVEC. Surprisingly, ß2GPI/anti-ß2GPI did not activate ECs harboring EMBI, illustrated by prevention of E-selectin and tissue factor (TF) expression. The inhibition of TF mRNA transcription was illustrated by quantitative RT-PCR. EMBI decreased the expression of phosphorylated JNK1/2, p38, HSP27 and enhanced phosphorylation of glycogen synthase kinase-3ß (pGSK3ß). Knocking down the GSK3ß expression by siRNA-GSK3ß, reduced the TF expression by ß2GPI/anti-ß2GPI-exposed-HUVEC. In-vivo, EMBI significantly decreased the percentage of fetal loss in naïve mice infused with anti-ß2GPI Abs, p<0.04. Thus, the dual activity of EMBI may introduce EMBI as a potential novel candidate peptide, to treat patients with APS.
