anti-dsDNA IgM Research Articles

T-bet-expressing B cells contribute to the autoreactive plasma cell pool in Lyn-/- mice.

Systemic Lupus Erythematosus (SLE) is characterized by pathogenic autoantibodies against nucleic acid-containing antigens. Understanding which B-cell subsets give rise to these autoantibodies may reveal therapeutic approaches for SLE that spare protective responses. Mice lacking the tyrosine kinase Lyn, which limits B and myeloid cell activation, develop lupus-like autoimmune diseases characterized by increased autoreactive plasma cells (PCs). We used a fate-mapping strategy to determine the contribution of T-bet+ B cells, a subset thought to be pathogenic in lupus, to the accumulation of PCs and autoantibodies in Lyn-/- mice. Approximately, 50% of splenic PCs in Lyn-/- mice originated from T-bet+ cells, a significant increase compared to WT mice. In vitro, splenic PCs derived from T-bet+ B cells secreted both IgM and IgG anti-dsDNA antibodies. To determine the role of these cells in autoantibody production in vivo, we prevented T-bet+ B cells from differentiating into PCs or class switching in Lyn-/- mice. This resulted in a partial reduction in splenic PCs and anti-dsDNA IgM and complete abrogation of anti-dsDNA IgG. Thus, T-bet+ B cells make an important contribution to the autoreactive PC pool in Lyn-/- mice.

The Role of IgM Antibodies in T Cell Lymphoma Protection in a Novel Model Resembling Anaplastic Large Cell Lymphoma.

MRL/lpr mice typically succumb to immune complex-mediated nephritis within the first year of life. However, MRL/lpr mice that only secrete IgM Abs because of activation-induced deaminase deficiency (AID-/-MRL/lpr mice) experienced a dramatic increase in survival. Further crossing of these mice to those incapable of making secretory IgM (μS mice) generated mice lacking any secreted Abs but with normal B cell receptors. Both strains revealed no kidney pathology, yet Ab-deficient mice still experienced high mortality. In this article, we report Ab-deficient MRL/lpr mice progressed to high-grade T cell lymphoma that can be reversed with injection of autoreactive IgM Abs or following adoptive transfer of IgM-secreting MRL/lpr B cells. Anti-nuclear Abs, particularly anti-dsDNA IgM Abs, exhibited tumor-killing activities against a murine T cell lymphoma cell line. Passive transfers of autoreactive IgM Abs into p53-deficient mice increased survival by delaying onset of T cell lymphoma. The lymphoma originated from a double-negative aberrant T cell population seen in MRL/lpr mice and most closely resembled human anaplastic large cell lymphoma. Combined, these results strongly implicate autoreactive IgM Abs in protection against T cell lymphoma.

Relationship between natural and infection-induced antibodies in systemic autoimmune diseases (SAD): SLE, SSc and RA.

Infection or vaccine-induced T cell-dependent immune response and the subsequent high-affinity neutralizing antibody production have been extensively studied, while the connection between natural autoantibodies (nAAbs) and disease-specific antibodies has not been thoroughly investigated. Our goal was to find the relationship between immunoglobulin (Ig)M and IgG isotype nAAbs and infection or vaccine-induced and disease-related autoantibody levels in systemic autoimmune diseases (SAD). A previously described indirect enzyme-linked immunosorbent assay (ELISA) test was used for detection of IgM/IgG nAAbs against citrate synthase (anti-CS) and F4 fragment (anti-F4) of DNA topoisomerase I in 374 SAD samples, with a special focus on systemic lupus erythematosus (SLE) (n=92), rheumatoid arthritis (n=73) and systemic sclerosis (n=157) disease groups. Anti-measles IgG and anti-dsDNA IgG/IgM autoantibodies were measured using commercial and in-house indirect ELISA tests. In all SAD groups the anti-measles IgG-seropositive cases showed significantly higher anti-CS IgG titers (P=0·011). In anti-dsDNA IgG-positive SLE patients, we detected significantly higher levels of anti-CS and anti-F4 IgG nAAbs (P=0·001 and<0·001, respectively). Additionally, we found increased levels of IgM isotypes of anti-CS and anti-F4 nAAbs in anti-dsDNA IgM-positive SLE patients (P=0·002 and 0·016, respectively). The association between IgG isotypes of pathogen- or autoimmune disease-related antibodies and the IgG nAAbs may underscore the immune response-inducible nature of the diseases investigated. The relationship between protective anti-dsDNA IgM and the IgM isotype of anti-F4 and anti-CS may provide immunoserological evidence for the beneficial roles of nAAbs in SLE patients.

Anti-Double-Stranded DNA Isotypes and Anti-C1q Antibody Improve the Diagnostic Specificity of Systemic Lupus Erythematosus.

Objectives We aimed to evaluate the value of immunoglobulin (Ig) G, IgM, and IgA isotypes of anti-double-stranded DNA (anti-dsDNA) and anti-C1q antibody in diagnosing systemic lupus erythematosus (SLE) patients and elucidate their association with disease activity and lupus nephritis. Methods Blood samples were obtained from 96 SLE patients, 62 other autoimmune disease patients, and 60 healthy blood donors. Anti-dsDNA IgG, IgM, and IgA isotypes and anti-C1q antibody were measured by enzyme-linked immunosorbent assay. Disease activity of SLE patients was assessed according to the SLE Disease Activity Index score. Results When specificity was greater than 90%, the sensitivity of anti-dsDNA IgG, IgM, and IgA isotypes and anti-C1q antibody in diagnosing SLE was 75%, 45%, 33%, and 49%, respectively. The prevalence of anti-dsDNA IgG (p = 0.002), anti-dsDNA IgA (p = 0.028), and anti-C1q antibody (p = 0.000) in active cases was significantly higher than those in inactive ones. In addition, the presence of anti-C1q antibody was associated with renal involvement (p = 0.032). Anti-dsDNA IgM showed no significant association with disease activity, but it was inversely linked with lupus nephritis (p = 0.005). When anti-dsDNA IgG and IgA and anti-C1q were combined to evaluate SLE disease activity, the specificity reached the highest level (90%). When anti-C1q positive was accompanied by anti-dsDNA IgM negative, the specificity of diagnosing lupus nephritis was up to 96%. Conclusions This study demonstrated the role of anti-dsDNA IgG, IgM, and IgA isotypes and anti-C1q antibody alone or combination in diagnosing SLE. Anti-dsDNA IgG and IgA and anti-C1q were shown to be associated with disease activity, while anti-dsDNA IgM and anti-C1q were associated with lupus nephritis. When the related antibodies were combined, the diagnostic specificity was significantly higher.

Suppression of lupus nephritis and skin lesions in MRL/lpr mice by administration of the topoisomerase I inhibitor irinotecan.

BackgroundSince the precise mechanism for the pathogenesis of systemic lupus erythematosus (SLE) is unknown, no targeted therapies in addition to immunosuppression are available so far. We recently demonstrated that administration of the topoisomerase I (topo I) inhibitor irinotecan at extremely low concentrations reversed established lupus nephritis in NZB/NZW mice. While profound immunosuppression was absent, we proposed changes in DNA relaxation and anti-double-stranded (ds)DNA antibody binding as the underlying mechanism. To exclude that these effects were restricted to NZB/NZW mice, irinotecan was used in a genetically different strain of lupus-prone mice.MethodsMRL/lpr mice were treated with high- and low-dose irinotecan beginning at 8 weeks of age. Treatment was repeated every fourth week. In vitro, DNA was relaxed by recombinant topo I, and altered anti-dsDNA antibody binding was measured by enzyme-linked immunosorbent assay.ResultsAdministration of both high- and low-dose irinotecan prevented proteinuria and prolonged survival in MRL/lpr mice. Moreover, both concentrations of irinotecan significantly improved histopathology of the skin at 18 weeks of age. While only high-dose irinotecan diminished the numbers of plasmablasts and double-negative T cells, no changes in IgG-secreting cells or anti-dsDNA IgG were observed. In vitro, relaxation of DNA by topo I increased the binding of anti-dsDNA IgG but not the binding of anti-dsDNA IgM derived from the plasma of MRL/lpr mice.ConclusionThe beneficial effects of topo I inhibition in a second, genetically different strain of lupus-prone mice strongly implicate irinotecan as a new therapeutic option for human SLE.

TNF blockade abrogates the induction of T cell-dependent humoral responses in an allotransplantation model

TNF blockade modulates many aspects of the immune response and is commonly used in a wide array of immune-mediated inflammatory diseases. As anti-TNF induces anti-dsDNA IgM antibodies but not other antinuclear reactivities in human arthritis, we investigated here the effect of TNF blockade on the induction of TD humoral responses using cardiac allograft and xenograft models. A single injection of an anti-rat TNF antibody in LEW.1A recipients grafted with congenic LEW.1W hearts almost completely abrogated the induction of IgM and IgG alloantibodies. This was associated with decreased Ig deposition and leukocyte infiltration in the graft at Day 5. TNF blockade did not affect germinal-center formation in the spleen or expression of Th1/Th2 cytokines, costimulatory and regulatory molecules, and TLRs in spleen and graft of the recipient animals. Clinically, the abrogation of the induction of the alloantibodies was associated with a marked prolongation of graft survival. In contrast, anti-TNF did not alter acute xenograft rejection mediated by TI antibodies in a hamster-to-rat model. Taken together, these data indicate that TNF blockade abrogates the induction of TD humoral responses and accordingly, may have a beneficial effect in antibody-mediated inflammatory pathologies.

Cognate interaction plays a key role in the surveillance of autoreactive B cells in induced mixed bone marrow chimerism in BXSB lupus mice

The effects of bone marrow transplantation (BMT) as a treatment for and/or preventive measure against autoimmune diseases in mice were investigated extensively. The reconstitution of the hematopoietic system with a mixture of autologous and heterologous bone marrow cells was reported to suppress the development of autoimmune diseases. However, the pathological mechanism through which mixed chimerism results in the suppression of disease development is still unknown. We have previously reported that the induction of fully major histocompatibility complex (MHC)-mismatched allogeneic mixed chimerism can prevent the disease development in BXSB mice. Interestingly, serum anti-dsDNA IgM antibody (anti-DNA IgM) levels were not significantly decreased in these chimeric mice, though other symptoms of autoimmune disease were ameliorated. In this study, we showed that self-reactive anti-DNA IgM production was mainly attributable to genetically normal B cells from the donor rather than genetically deficient B cells from the host. Host-type B cells responded normally to foreign antigens and produced the appropriate antibodies. BMT from fully MHC-matched or haplo-identical donors could suppress the production of anti-DNA antibodies. Our present study suggests the existence of a surveillance system dependent on the recognition of MHC molecules on B cells.

Apoptosis and Autoimmunity Induced by Clodronate in Systemic Lupus Erythematosus Mononuclear Circulating Cells

The aim of this study is to evaluate the effect of clodronate on apoptosis of human systemic lupus erythematosus circulating mononuclear cells and to analyze possible correlations with changes in autoantibody production in vitro. Lympho-monocytes from 20 SLE patients were isolated and incubated with or without addition of 1 microM clodronate for 72 hours. Apoptosis and release of genomic material was assessed by immunofluorescent detection of cleaved caspase-3 and by Cell-Death-Detection ELISAPLUS kit (Roche). Anti-Nucleosome IgG and anti-dsDNA IgM and IgG autoantibody levels were determined in supernatants by commercially available ELISA kits. Clodronate induced apoptosis in monocytes as confirmed by cleaved caspase-3 immunostaining and by quantification of cleaved nucleosome in the supernatants (treated 0.22+/-0.05 O.D. vs untreated 0.09+/-0.04 O.D.; P less than 0.001). This finding was coupled with a significant increasing in supernatants of IgG anti-Nucleosome (treated 6.5+/-1.1 vs untreated 5.5+/-0.6 IU/mL; p=0.001) and IgM (treated 3.0+/-1.3 vs 2.2+/-0.9 IU/mL; p=0.02) and IgG (treated 4.0+/-1.8 vs untreated 2.8+/-1.5 IU/mL; p=0.02) anti-dsDNA autoantibody levels. Our findings stressed the pro-apoptotic activity of clodronate, as well as its potential autoimmunity induction in SLE mononuclear circulating cells. Clinical studies could clarify the role of bisphosphonates on autoantibody production and worsening of disease activity.

Pericarditis and chronic inflammatory demyelinating polyneuropathy during therapy with pegylated interferon alfa-2a for chronic hepatitis C

We report a case of pericarditis and chronic inflammatory demyelinating polyneuropathy with biological signs of a lupus-like syndrome due to pegylated interferon alfa-2a therapy during treatment for chronic hepatitis C. The patient developed moderate weakness in the lower limbs and dyspnea. He was hospitalized for congestive heart failure. An electrocardiogram showed gradual ST-segment elevation in leads V(1) through V(6) without coronary artery disease. A transthoracic cardiac ultrasonographic study revealed moderate pericardial effusion with normal left ventricular function. Anti-DNA antibody and antids DNA IgM were positive. Neurological examination revealed a symmetrical predominantly sensory polyneuropathy with impairment of light touch and pin prick in globe and stoking-like distribution. Treatment with prednisolone improved the pericarditis and motor nerve disturbance and the treatment with intravenous immunoglobulin improved the sensory nerve disturbance.

Anti-dsDNA antibodies in Brazilian patients of mainly African descent with systemic lupus erythematosus: lack of association with lupus nephritis

Renal disease is associated with morbidity and mortality in systemic lupus erythematosus (SLE) and anti-dsDNA antibodies with SLE immunopathogenesis. We investigated the dsDNA antibody profile of 84 Brazilian SLE patients, 27 with lupus nephritis. Thirty-six (39.1%) patients had dsDNA IgG antibodies shown in enzyme-linked immunosorbent assay (454.7 +/- 281.1 WHO units/mL), nine presenting renal disease. The following profile of dsDNA antibodies was demonstrated in Crithidia luciliae test: IgA (seven out of 36; 19.4%), IgG (22 out of 36, 66.1%); IgM (nine out of 36, 25.0%), and IgE (four out of 36, 11.1%). Two or three isotypes of dsDNA antibodies were observed in nine (25.0%) patients, while 11 (30.5%) were seronegative in the C. luciliae test. Patients with dsDNA antibodies had lower serum C3 and C4 when compared with SLE individuals without these immunoglobulins (P < 0.01 and P < 0.001, respectively). There was no association between any dsDNA antibody isotype and lupus kidney disease nor was anti-dsDNA IgM antibody associated with absence of nephritis.

Diagnostik der Autoimmunerkrankungen

Autoantibodies play a key role in diagnostic laboratories as markers of autoimmune diseases. In addition to their role as markers they mediate diverse effects in vivo. Autoantibodies with protective effect have been described. Natural protective IgM autoantibodies against tumour-antigens of malignant cells or their precursors may contribute to increased survival rates of carcinoma patients. In a mouse model of systemic lupus erythematosus it has been shown that anti-dsDNA IgM autoantibodies protect from glomerular damage. In contrast, a direct pathogenic role of autoantibodies has been well established e.g. in myasthenia gravis or in Goodpasture syndrome. Similarly autoantibodies against SSA Ro52 are detrimental in neonatal lupus erythematosus with congenital heart block. Moreover, putatively protective autoantibodies may become pathogenic during the course of the disease such as the onconeuronal autoantibodies whose pathogenicity depends on their compartmentalisation. In patients with paraneoplastic syndromes tumour cells express proteins that are also naturally present in the brain. Anti-tumour autoantibodies which temporarily suppress tumour growth can provoke an autoimmune attack on neurons once having crossed the blood-brain barrier and cause specific neurological symptoms. Only a restricted number of autoantibodies are useful follow-up markers for the effectiveness of treatment in autoimmune diseases. Certain autoantibodies hold prognostic value and appear years or even decades before the diagnosis of disease such as the antimitochondrial antibodies in primary biliary cirrhosis or anti-citrullinated protein (CCP)-antibodies in rheumatoid arthritis. It is crucial to know whether the autoantibodies in question recognise linear or conformational epitopes in order to choose the appropriate detection methods. Indirect immunofluorescence microscopy remains a very useful tool for confirmation of results of commercially available immunoassays and for detection of special and rare autoantibodies that otherwise often remain undetected. Standardisation of autoimmune diagnostics is still underway and requires joint efforts by laboratories, clinicians and industry.