DNA–histone complexes as ligands amplify cell penetration and nuclear targeting of anti‐DNA antibodies via energy‐independent mechanisms

Abstract

SummaryWe have generated three monoclonal cell-penetrating antibodies (CPAbs) from a non-immunized lupus-prone (NZB 3 NZW)F 1 mouse that exhibited high anti-DNA serum titres. These CPAbs are polyreactive because they bind to DNA and other cellular components, and localize mainly in the nucleus of HeLa cells, albeit with a distinct nuclear labelling profile. Herein, we have examined whether DNA-histone complexes (DHC) binding to CPAbs, before cell entry, could modify the cell penetration of CPAbs or their nuclear staining properties. By applying confocal microscopy and image analysis, we found that extracellular binding of purified CPAbs to DHC significantly enhanced their subsequent cell-entry, both in terms of percentages of positively labelled cells and fluorescence intensity (internalized CPAb amount), whereas there was a variable effect on their nuclear staining profile. Internalization of CPAbs, either alone or bound to DHC, remained unaltered after the addition of endocytosis-specific inhibitors at 37°or assay performance at 4°, suggesting the involvement of energy-independent mechanisms in the internalization process. These findings assign to CPAbs a more complex pathogenetic role in systemic lupus erythematosus where both CPAbs and nuclear components are abundant.

Anti-double Stranded DNA Antibodies: Origin, Pathogenicity, and Targeted Therapies

“…Glomerular cells, hepatocytes, monocytes, fibroblasts, and neuronal cells are vulnerable to penetration by anti-DNA antibodies, mirroring the findings in the liver, spleen, and skin after treatment with penetrating antibodies in vivo (68, 69). The cellular penetration of antibodies is assisted by F(ab)′2 fragments with the mediation of the antigen-antibody binding region, which is also temperature-dependent and energy-consuming (70). Although the Fc fragment of an anti-DNA antibody contributes to its binding activity with monogamous bivalency, in which both Fab combining sites come into contact with DNA, the binding is not inhibited by the blockage of Fc receptor in mesangial cells (71, 72).…”

A robust strategy for proteomic identification of biomarkers of invasive phenotype complexed with extracellular heat shock proteins

“…The capability to capture and analyze extracellular histone is clinically significant in tumor progression and inflammatory disease (Marsman et al 2016;Jiang et al 2017). Histone and HSP60 association may provide a mechanism for plasma membrane translocation of chaperome export without endosomal involvement in an ATP-independent manner (Hariton-Gazal et al 2003;Zannikou et al 2016). Cells in proliferative and inflammatory phenotypes engage in metabolic pathways favoring biosynthesis, with certain glycolytic enzymes universally bundled with extracellular HSP complexes, may also export non-enzymatic "moonlighting functions" including cell adhesion and extracellular matrix modification (Min et al 2016;Jeffery 2018).…”

Monoclonal anti-dsDNA antibody 2C10 escorts DNA to intracellular DNA sensors in normal mononuclear cells and stimulates secretion of multiple cytokines implicated in lupus pathogenesis

“…Subsequently, numerous studies referring to cellinternalizable anti-DNA antibodies have been conducted using different assay conditions. Many possible means by which antibodies can enter cells have been implicated, including via Fcγ receptors [24,26], an unidentified nucleosome receptor [27], DNA-histone complexes [28], glycosaminoglycans [29] and myosin 1 [30]. In SLE, apoptosis is enhanced [31] and clearance of the apoptotic debris is compromised [2,32], resulting in higher concentrations of DNA or nucleosomes in the sera of patients relative to healthy controls.…”