Serum Levels Of anti-DNA Antibodies Research Articles

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

Systemic lupus erythematosus (SLE) is characterized by high-titer serological autoantibodies, including antibodies that bind to double-stranded DNA (dsDNA). The origin, specificity, and pathogenicity of anti-dsDNA antibodies have been studied from a wider perspective. These autoantibodies have been suggested to contribute to multiple end-organ injuries, especially to lupus nephritis, in patients with SLE. Moreover, serum levels of anti-DNA antibodies fluctuate with disease activity in patients with SLE. By directly binding to self-antigens or indirectly forming immune complexes, anti-dsDNA antibodies can accumulate in the glomerular and tubular basement membrane. These autoantibodies can also trigger the complement cascade, penetrate into living cells, modulate gene expression, and even induce profibrotic phenotypes of renal cells. In addition, the expression of suppressor of cytokine signaling 1 is reduced by anti-DNA antibodies simultaneously with upregulation of profibrotic genes. Anti-dsDNA antibodies may even participate in the pathogenesis of SLE by catalyzing hydrolysis of certain DNA molecules or peptides in cells. Recently, anti-dsDNA antibodies have been explored in greater depth as a therapeutic target in the management of SLE. A substantial amount of data indicates that blockade of pathogenic anti-dsDNA antibodies can prevent or even reverse organ damage in murine models of SLE. This review focuses on the recent research advances regarding the origin, specificity, classification, and pathogenicity of anti-dsDNA antibodies and highlights the emerging therapies associated with them.

Intravenous immune globulin therapy of lupus nephritis: use of pathogenic anti-DNA-reactive IgG

The authors have recently shown that antibodies with anti-idiotype (Id) specificity to pathogenic Ids of lupus nephritis may occasionally occur in several intravenous immune globulin (IVIG) preparations because they are present in healthy donors and the healthy relatives of SLE patients. In the present study, the authors purified these anti-Ids and treated two SLE patients with nephritis in parallel with conventional high-dose IVIG management with a commercial preparation (IVIG 6) in three controls for two months. Because pathogenic Ids of anti-DNA molecules, such as both 8.12 and F4 Ids, show a cationic mobility in isoelectric focusing, a commercial preparation of IVIG (11) was absorbed on a Sepharose column coupled with DC-305-39 myeloma protein, namely an 8.12+ and F4+ cationic IgG. Infusion of the eluate (EL-11) induced a prompt resolution of proteinuria levels and an evident decrease of serum levels of anti-DNA antibodies in both patients, whereas in the three controls, proteinuria and anti-DNA antibodies were scarcely reduced. In addition, plasma levels of interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha were also significantly influenced by both treatments. The mean values of both cytokines increased significantly after 1 h and then progressively declined over the next 48 h. It was of interest, however, that the increased TNF-alpha in the two EL-11-treated patients was significantly lower than in the three controls. The data suggest that reduction of active lupus nephritis by enriched specific anti-Id molecules is the result of two (or perhaps more) mechanisms: suppression of pathogenic idiotypes at the cellular level and improvement in the mesangium of the secretion of anti-inflammatory cytokines, such as IL-6, whose defective function is related to the autoimmune disorder.

Complement receptor of the immunoglobulin superfamily reduces murine lupus nephritis and cutaneous disease

Complement activation takes place in autoimmune diseases and accounts for tissue inflammation. Previously, complement inhibition has been considered for the treatment of SLE. Complement receptor of the immunoglobulin superfamily (CRIg) is a selective inhibitor of the alternative pathway of complement and a soluble form reverses established inflammation and bone destruction in experimental autoimmune arthritis. We asked whether specific inhibition of the alternative pathway could inhibit autoimmunity and/or organ damage in lupus-prone mice. Accordingly, we treated lupus-prone MRL/lpr mice with a soluble form of CRIg (CRIg-Fc) and we found that it significantly diminished skin lesions, proteinuria and pyuria, and kidney pathology. Interestingly, serum levels of anti-DNA antibodies were not affected despite the fact that serum complement 3 (C3) levels increased significantly. Immunofluorescent staining of kidney tissues revealed a reduction in staining intensity for C3, IgG, and the macrophage marker Mac-2. Thus our data show that inhibition of the alternative pathway of complement controls skin and kidney inflammation even in the absence of an effect on the production of autoantibodies. We propose that CRIg should be considered for clinical trials in patients with systemic lupus erythematosus.

Systemic Lupus Erythematous and Graves Disease

Despite the common genetic predisposition and autoimmune features of both disorders, Graves disease (GD) has been described quite infrequently in patients with systemic lupus erythematous (SLE; average incidence of 2.8% vs. 1.9% in general population). We present a patient with SLE who developed hyperthyroidism. A 57-year-old woman, followed since 1998 for lupus nephritis, was admitted for clinical evaluation of hyperthyroidism 5 years after the diagnosis of SLE. Her symptoms included heat intolerance, tremor, and irritability. Clinical examination showed diffuse thyroid gland enlargement with a vascular murmur on auscultation. Hormonal assays showed markedly increased free T3 and T4 levels and suppressed thyroid-stimulating hormone levels with circulating thyroid-stimulating hormone receptor antibodies. Graves disease responded well to carbimazole treatment and beta-blockers. The patient had a subtotal thyroidectomy, later. The patient was on 10 mg of prednisolone maintenance therapy when hyperthyroidism was discovered. Concomitantly, a slight increase in serum creatinine and serum levels of anti-DNA antibodies and complement activation without other abnormalities were found. A third renal biopsy showed mononuclear interstitial infiltration but no glomerular signs of lupus activity. Patients with SLE are likely to be at increased risk for thyroid disease.

Contribution of Major Histocompatibility Complex (MHC) to Upregulation of Anti-DNA Antibody in Transgenic Mice

Genes linked to the MHC class II contribute to human and murine lupus, but multiple genes are required to produce and upregulate pathogenic autoantibodies. In NZB/NZW mice, nephritogenic IgG anti-dsDNA is provided by NZW (H-2z), but the origin of the upregulating signals is unknown. They could be from NZB (H-2d) or NZW (H-2z) or require heterozygocity. Our aim was to determine whether NZW can provide upregulating signals for the nephritogenic autoantibody introduced to normal mice via transgenes encoding a NZB/NZW IgG2a antibody to DNA. These transgenic mice spontaneously secrete serum IgG2a anti-DNA, some develop clinical nephritis with proteinuria and azotemia, but none die of fatal nephritis. We bred mice to produce offspring of H-2b/d, H-2b/b, H-2b/z and H-2d/z haplotypes (H-2b, H-2d and H-2z derived from C57BL/6, BALB/c and NZW, respectively). Transgenic H-2b/d mice had significantly higher levels of serum anti-DNA antibodies compared with H-2b/b haplotypes from 20 to 40 weeks of age (P < 0.05). However, unlike NZB/NZW mice, they did not show sustained upregulation of anti-DNA antibodies. The serum levels of IgG anti-DNA of transgenic mice declined after 30 weeks of age. In order to determine whether NZW can provide upregulating signals, we introduced the NZW background into transgenic H-2b/d mice in an attempt to increase both quantities of anti-DNA and prevalence of nephritis. However, serum levels of anti-DNA antibodies were similar in transgenic mice of H-2b/z and H-2d/z haplotypes. The anti-DNA levels declined with age in both groups. No mice developed fatal nephritis.(ABSTRACT TRUNCATED AT 250 WORDS)

A conserved anti-DNA antibody idiotype associated with nephritis in murine and human systemic lupus erythematosus.

In order to identify unique structural features of pathogenic autoantibodies to DNA in SLE, a murine anti-anti-DNA (anti-Id) mAb (mAb 1C7) was produced in response to immunization of lupus mice with a syngeneic anti-DNA mAb (mAb 3E10). Immunization of lupus mice with mAb 3E10 inhibited production of native anti-DNA antibodies, suppressed development of lupus kidney disease (nephritis), and induced production of anti-anti-DNA (anti-Id) antibodies. mAb 1C7 bound F(ab')2 fragments of mAb 3E10, and it bound other murine anti-DNA mAb, but not murine mAb or polyclonal serum antibodies unreactive with DNA. Moreover, binding of mAb 1C7 anti-Id to mAb 3E10 was inhibited by DNA, suggesting anti-Id binding within or near the binding site for DNA. Furthermore, mAb 1C7 bound serum IgG immunoglobulins from 9/12 patients with lupus nephritis and serum anti-DNA antibodies compared to only 3/12 SLE patients with comparable serum levels of anti-DNA antibodies, but without nephritis (p = 0.04), and only 1/53 SLE patients without serum anti-DNA antibodies, 0/49 patients with rheumatoid arthritis, and 1/47 healthy subjects (p less than 0.001). These results provide evidence that mAb 1C7 identifies a conserved Id associated with anti-DNA antibodies in murine and human SLE and may be useful as a structural probe to characterize pathogenic anti-DNA antibodies in SLE.