Antiphospholipid reactivity against cardiolipin metabolites occurring during endothelial cell apoptosis

Abstract

We have recently shown that cardiolipin (CL) and its metabolites move from mitochondria to other cellular membranes during death receptor-mediated apoptosis. In this study, we investigate the immunoreactivity to CL derivatives occurring during endothelial apoptosis in patients with antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE). We compared the serum immunoreactivity to CL with that of its derivatives monolysocardiolipin (MCL), dilysocardiolipin (DCL), and hydrocardiolipin (HCL) by means of both enzyme-linked immunosorbent assay and thin-layer chromatography (TLC) immunostaining. In addition, we investigated the composition of phospholipid extracts from the plasma membrane of apoptotic endothelial cells and the binding of patients' sera to the surface of the same cells by using high-performance TLC and immunofluorescence analysis. The average reactivity to MCL was comparable with that of CL and significantly higher than that for DCL and HCL in patients studied, both in the presence or in the absence of beta 2 -glycoprotein I. Of relevance for the pathogenic role of these autoantibodies, immunoglobulin G from patients' sera showed an increased focal reactivity with the plasma membrane of endothelial cells undergoing apoptosis. Interestingly, the phospholipid analysis of these light membrane fractions showed an accumulation of both CL and MCL. Our results demonstrated that a critical number of acyl chains in CL derivatives is important for the binding of antiphospholipid antibodies and that MCL is an antigenic target with immunoreactivity comparable with CL in APS and SLE. Our finding also suggests a link between apoptotic perturbation of CL metabolism and the production of these antibodies.

Single-step autoantibody profiling in antiphospholipid syndrome using a multi-line dot assay

“…It should be noted that this study provides data consistent with the conclusion that not all clinically relevant aPL are only directed against proteins [ 6 , 30 , 31 ]. The phospholipids employed in the MLDA for the detection of aPL antibodies are immobilized in the absence of co-factors like β2 GPI and the only source thereof could be proteins from the patient samples analyzed.…”

Plasma cholinesterase and carboxylesterase activities and nuclear and mitochondrial lipid composition of human placenta associated with maternal exposure to pesticides

“…Therefore, we hypothesize that pesticide environmental exposure during pregnancy modifies placental ROS levels affecting the redox-sensitive signals involved in cell proliferation. However, considering that cardiolipin and oxidized cardiolipin species comigrate in the TLC used to separate phospholipids [62], oxidative injury of the LM organelle characteristic of the syncytiotrophoblast cannot be discarded. As the transfer of pesticides from maternal circulation ocurrs across the endothelial-syncytial membrane of the placenta it may contribute to the injury of the syncytiotrophoblast, which would lead to repair by hyperplasia of the cytotrophoblast.…”

Enrichment of Complement, Immunoglobulins, and Autoantibody Targets in the Proteome of Platelets from Patients with Systemic Lupus Erythematosus

“… 60 65 66 67 Clearance of apoptotic cells is tightly regulated and chiefly dependent on signals on the cell surface. 68 It has been shown that a disturbed apoptotic process and membrane changes can promote a breach in tolerance 18 and an increase in reactivity of antiphospholipid antibodies, 69 but the accumulation of APS-related autoantigens in platelets is to our knowledge a novel finding, suggesting that platelets may be an overlooked source of autoantigens in SLE. 1 It should be noted, however, that no patient in this study had APS (one from the SLE low and one from the SLE nor group were positive for anti-β2GPI antibodies).…”