Anti-dsDNA Antibodies Bind to Mesangial Annexin II in Lupus Nephritis

Abstract

Production of anti-dsDNA antibodies is a hallmark of lupus nephritis, but how these antibodies deposit in organs and elicit inflammatory damage remains unknown. In this study, we sought to identify antigens on the surface of human mesangial cells (HMC) that mediate the binding of human anti-dsDNA antibodies and the subsequent pathogenic processes. We isolated anti-dsDNA antibodies from patients with lupus nephritis by affinity chromatography. We used multiple methods to identify and characterize antigens from the plasma membrane fraction of mesangial cells that crossreacted with the anti-dsDNA antibodies. We found that annexin II mediated the binding of anti-dsDNA antibodies to HMC. After binding to the mesangial cell surface, anti-dsDNA antibodies were internalized into the cytoplasm and nucleus. This also led to induction of IL-6 secretion and annexin II synthesis, mediated through activation of p38 MAPK, JNK, and AKT. Binding of anti-dsDNA antibodies to annexin II correlated with disease activity in human lupus nephritis. Glomerular expression of annexin II correlated with the severity of nephritis, and annexin II colocalized with IgG and C3 deposits in both human and murine lupus nephritis. Gene silencing of annexin II in HMC reduced binding of anti-dsDNA antibody and partially decreased IL-6 secretion. In summary, our data demonstrate that annexin II mediates the binding of anti-dsDNA antibodies to mesangial cells, contributing to the pathogenesis of lupus nephritis. This interaction provides a potential target for therapeutic intervention.

Anti-alpha-actinin antibodies are part of the anti-cell membrane antibody spectrum that characterize patients with lupus nephritis

“…Anti-MbA activate multiple pathways such as protein kinase C [45], AKT mTor, and the p38 MAPK [21,46]. Interestingly, blockade of the PKC pathway by mycophenolate mofetil (MMF), the PI3K/AKT/mTor pathway by rapamycin, or blockade of the p38 MAPK pathway are both effective for treating the disease [45,47,48].…”

“…Cells were grown in DMEM (Invitrogen, Carlsbad, CA) supplemented with 2 mM L-glutamine (Promega, Mannheim, Germany), 10% fetal calf sera (Eurobio, Les Ulis, France), and antibiotics. At confluence, the cells were harvested using 0.25% trypsineEDTA (Eurobio), washed, and cultured overnight in suspension before staining as described [21].…”

Basic and Translational Concepts of Immune-Mediated Glomerular Diseases

“…178 Mesangial deposits have also been associated with antibody to mesangial cell annexin, which co-localizes with IgG and C3 and correlates with disease activity. 179 However, most recent studies conclude that deposited anti-DNA reacts with extracellular DNA in the form of nucleosomes that consist of an anionic segment of DNA wound around a highly cationic histone core, giving the structure a net positive charge and thereby a high affinity for glomerular anionic sites. 171,172 Defective apoptosis in SLE, perhaps related to an acquired defect in DNAse I, leads to necrosis and release of chromatin debris from apoptotic blebs allowing access of nucleosomes to antigen-presenting DCs as well as entry into the circulation.…”

Glomerular Autoimmune Multicomponents of Human Lupus Nephritis In Vivo

“…[6][7][8][9][10][11][12] They consider a pre-eminent role of circulating anti-double stranded DNA (dsDNA) antibodies that they can interact, for mimicry, with glomerular antigens expressed at the cell surface of podocytes and mesangial cells 7,[13][14][15] or in the glomerular basement membrane. 12,[16][17][18][19][20] Chromatin and nucleosomes deriving from ineffective fragmentation may interact with negatively charged constituents of the basement membrane 7,16 and become the planted antigen for anti-dsDNA (and autoantibodies of other specificities).…”