Detection of Annexin A2 in Systemic Lupus Erythematosus

There is substantial clinical and biological intra and inter-patient variability in SLE. Vascular, renal and neurologic deficiency can be organ-threatening or even life-threatening, leading to increased morbidity and mortality. Thus, biomarkers of disease activity and prognosis are required for regular follow-up of SLE patients. Implication of Toll-like Receptors (TLRs) in SLE has been extensively studied in mice models and humans. Self nuclear antigens bind to TLRs which are located on the surface of dendritic cells, B-cells, and endothelial cells, leading to production of pro-inflammatory cytokines and pathologic autoantibodies involved in organ dysfunction of SLE patients. Moreover, TLR expression in SLE is significantly higher and significantly correlated with disease activity. Annexin A2 (ANXA2) is a member of the annexins superfamily which exists as a monomer or heterotetramer and is implicated in several biological processes. Most notably, it binds to ẞ2GP1/anti-ẞ2GP1 antibodies and mediates endothelial cell activation via a TLR4 signaling pathway, highlighting its key role in Antiphospholipid Syndrome (APS) frequently associated with SLE. ANXA2 is also involved in the physiopathology of SLE. Anti-DNA autoantibodies can bind with ANXA2 expressed on mesangial cells in lupus nephritis. Besides, a french study carried out in Amiens' University Hospital showed that vascular lesions in lupus nephritis were associated with a significant increase in vascular expression of ANXA2.