Diversity of DNA‐hydrolyzing antibodies from the sera of autoimmune‐prone MRL/MpJ‐lpr mice

Abstract

It has been shown for the first time that polyclonal IgG abzymes (Abzs) with DNase activity from the sera of autoimmune-prone MRL/MpJ-lpr mice can be separated by isoelectric focusing into many subfractions having the isoelectric points (pI) from 4.5 to 9, with the maximal activity for Abzs with pI = 6.5-9.0. Affinity chromatography on DNA-cellulose separated DNase IgGs into many subfractions demonstrating a range of affinities for DNA and different levels of the relative DNase activities (RDA) due to intrinsically bound metals and after addition of external Mg(2+) , Mn(2+) , Ca(2+), and Mg(2+) +Ca(2+). Some fractions significantly increase RDAs in the presence of external ions (Mg(2+) + Ca(2+) > Mg(2+) > Mn(2+) > Ca(2+)), while each of this cofactor can also inhibit or have no influence on the RDAs of another fractions. It is known that complexes of DNA with histones and other proteins of apoptotic cells are the primary immunogens in systemic lupus erythematosus (SLE). Bovine serum albumin (BSA) and methylated BSA (mBSA) increase the RDAs of only some fractions, while have no effect or inhibit other IgG fractions. The ratio of the RDAs in the presence of all metal ions, BSA, and mBSA was individual for every abzyme fraction. Mn(2+) and Ca(2+) stimulated accumulation of only relaxed form of supercoiled DNA (scDNA) in the case of all subfractions, while in the presence of Mg(2+) antibodies (Abs) of some subfractions (and in the presence of Mn(2+) +Ca(2+) all subfractions) produced relaxed DNA (rDNA) and linear DNA (linDNA) in a variable extent. The data obtained show that the polyclonal Abzs of mice may be a cocktail of Abs directly to DNA, RNA, and their complexes with proteins and anti-idiotypic Abs to active centers of different nucleases. The diversity of the physicochemical and kinetic characteristics of the Abzs seems to be significantly widened when pre-diseased mice spontaneously develop the disease.

Anti-Double-Stranded DNA IgG Participates in Renal Fibrosis through Suppressing the Suppressor of Cytokine Signaling 1 Signals

“…Although these results came from in vitro experiments, we can suppose that anti-dsDNA IgG harbors such catalytic activity intracellularly or even in vivo . In fact, anti-dsDNA IgG exhibits catalytic effects on bound self-antigens frequently, and the DNA cleavage and proteolysis are pivotal in the nephritogenicity of anti-dsDNA IgG (36, 43). Hence, the binding to and catalyzing of KIR of anti-dsDNA IgG may reasonably explain its inhibition of SOCS1 signaling, but without affecting the mRNA expression of SOCS1.…”

Anti-DNA antibody mediated catalysis is isotype dependent

“…Researchers have previously studied the catalytic properties of polyclonal anti-DNA antibodies obtained from lupus patients and murine lupus models (Shuster et al, 1992; Nevinsky et al, 2002; Kostrikina et al, 2011; Kozyr et al, 2002; Suchkov et al, 2001). These studies indicated an intrinsic relationship between the DNase activity of anti-DNA antibodies and bound metal ions, and suggested that the cytotoxicity of anti-DNA antibodies may be due to their hydrolysis of nuclear matrix proteins (Nevinsky et al, 2002; Kostrikina et al, 2011; Kozyr et al, 2002; Mouratou et al, 2002; Cavallo et al, 2012; Gololobov et al, 1997).…”

“…These studies indicated an intrinsic relationship between the DNase activity of anti-DNA antibodies and bound metal ions, and suggested that the cytotoxicity of anti-DNA antibodies may be due to their hydrolysis of nuclear matrix proteins (Nevinsky et al, 2002; Kostrikina et al, 2011; Kozyr et al, 2002; Mouratou et al, 2002; Cavallo et al, 2012; Gololobov et al, 1997). In contrast, we used monoclonal anti-DNA antibodies containing both heavy and light chains that have more stable and definable affinity for antigens than polyclonal antibodies isolated from sera.…”

“…Remarkably, the concentrations of double stranded (ds) and single stranded (ss) DNA-hydrolyzing autoantibodies are elevated in the sera of patients with SLE and in murine lupus models, suggesting a role in disease (Nevinsky et al, 2002; Kostrikina et al, 2011; Ponomarenko et al, 2002). Catalyzing anti-DNA antibodies may share with DNase I several similar, or even identical, amino acid residues, which are necessary for DNA hydrolysis and the binding of magnesium and calcium ions (Kostrikina et al, 2014).…”

A nucleolytic lupus autoantibody is toxic to BRCA2-deficient cancer cells

“…The findings presented herein also strengthen the rationale for continuing the search for lupus autoantibodies that may have even greater and more selective effects on cancer cells. Given the diversity of autoantibodies associated with SLE19 we are confident that additional lupus autoantibodies with therapeutic potential await discovery.…”