Suppression of NZB/NZW murine nephritis by administration of a syngeneic monoclonal antibody to DNA. Possible role of anti-idiotypic antibodies

Manipulation of idiotype networks in autoimmunity

The spontaneous occurrence of anti-idiotypes associated with the amelioration of disease activity in some autoimmune disorders encourages the view that one may be able to develop a therapeutic strategy based upon manipulation of idiotype networks. Attempts to abrogate autoimmunity by using heterologous anti-idiotype reagents have been rather disappointing and there may well be an expansion of idiotype-negative antibody clones. We argue that idiotypic reagents based on T cells or antibodies derived from the species being treated are more likely to lead to success because they interact more profoundly with the individual's own networks than do heterologous antibodies.

In vitro and in vivo expression of a nephritogenic Ig heavy chain determinant: pathogenic autoreactivity requires permissive light chains

Lymphocyte antigen receptors are promising targets for immune intervention strategies in disorders marked by repertoire skewing or expansion of lymphocyte subsets. Appropriate application of immune receptor modulation is predicated on understanding the role of a particular receptor in pathogenesis and disease regulation. The VHB/W16 gene, restricted to mice carrying the j haplotype for the J558 family, is overexpressed by murine lupus anti-DNA Ig. This gene is also expressed recurrently among nephritogenic anti-DNA Ig recovered from several autoimmune strains, suggesting that cells expressing this pathogenic receptor are positively selected during disease progression. To explore the extent and mechanisms by which Ig H chains expressing this gene contribute to autoimmunity, an Ig H chain gene was engineered for in vitro and in vivo recombination studies. Site-directed mutagenesis generated unique restriction sites to link PCR-amplified V region (VDJ) cDNA to previously isolated genomic fragments containing Ig regulatory and signal sequences. The new 3 kb VDJ gene was then ligated to a 9 kb fragment encoding the IgM constant region. Transfection of H chain loss variant myeloma with the complete 12 kb construct, termed 238H-Cmicro, resulted in secretion of intact Ig pairing 238H-Cmicro, with a lambda L chain; however, transfectant Ig lacked autoreactivity and pathogenicity. Introduction of the 238H-Cmicro H chain as a transgene onto the non-autoimmune C57BL/6 background resulted in abundant B cell surface expression of 238H-Cmicro, however, four transgenic Ig recovered by fusion of LPS-stimulated splenocytes and formed by combination of 238H-Cmicro, with endogenous kappa chains do not bind DNA or laminin. These results indicate that the antigen binding sites encoded by this disease-associated gene and/or H chain must associate with permissive L chains to specify autoimmunity. The 238H-Cmicro, transgenic model should prove useful in dissecting the in vivo fate of 238H-Cmicro, L combinations that produce pathogenic autoreactive receptors and in evaluating receptor-targeted interventions.

Highly cationic anti-DNA antibodies in patients with lupus nephritis analyzed by two-dimensional electrophoresis and immunoblotting

The relationship between chemical properties of anti-DNA antibodies (Abs) and lupus nephritis was investigated. The anti-DNA Abs in sera from systemic lupus erythematosus (SLE) patients were separated by two-dimensional electrophoresis (2-DE) and immunoblotting with goat anti-human IgG Abs. Highly cationic anti-DNA Abs were detected in deoxyribonuclease I (DNase I)-treated sera from patients with lupus nephritis (in 8 of 9 cases) but not in the sera from SLE patients without nephritis (in 0 of 9 cases), normal subjects, or patients with other renal diseases (in 0 of 7 cases). The mean titers of anti-dsDNA Abs in patients with lupus nephritis were not significantly different from those in SLE patients without nephritis. The highly cationic anti-DNA Abs in the sera disappeared after incubation with heparin-Sepharose. These results suggest that highly cationic anti-DNA Abs are specific for lupus nephritis and may be involved in development of lupus nephritis via the binding to glycosaminoglycans on the endothelial cell surface.

Treatment with dsDNA-anti-dsDNA antibody complexes extends survival, decreases anti-dsDNA antibody production and reduces severity of nephritis in MRLlpr mice

Lupus nephritis results from the deposition on the glomerular basement membrane of antibodies cross-reacting with dsDNA. In an attempt to suppress the production of such antibodies in the MRLlpr mouse strain, mice were treated by injections of dsDNA-anti-dsDNA antibody complexes formed in an excess of syngeneic polyclonal antibodies to increase the immunogenicity of idiotypes. A first group of mice was treated after the onset of high-affinity anti-dsDNA IgG antibodies (3 months). We show here that fortnightly injections of dsDNA-anti-dsDNA antibody complexes significantly extend mouse survival over that of two control groups treated with either the carrier buffer or with sham complexes. Treated mice produced 5-fold less anti-dsDNA antibodies than control mice and presented a reduced nephritis activity index at the age of 7 months. Specific anti-idiotypic antibody levels were not modified in the treated group, while showing a sharp decrease in the control group between months 6 and 7. Mice of a second group were started on injections of dsDNA-anti-dsDNA complexes at the age of 4 months when nephritis was already ongoing, and were followed until death while receiving fortnightly injections. Forty percent of the treated mice were still alive after one year, while none of the control mice survived. dsDNA-anti-dsDNA complexes have therefore the potential of reducing the production of anti-dsDNA antibody production and the severity of nephritis in MRLlpr mice. These findings could be relevant for the treatment of human lupus.

Increased release of von Willebrand factor antigen from endothelial cells by anti-DNA autoantibodies

OBJECTIVE

To determine whether antibodies to double stranded DNA (anti-dsDNA) have a pathogenic role in systemic lupus erythematosus (SLE).

METHODS

IgG was purified from 17 patients with SLE (median anti-dsDNA titre 1212 IU/ml) and nine healthy controls (median titre 40 IU/ml). Anti-dsDNA depleted polyclonal IgG (median anti-dsDNA titre 17 IU/ml) was also prepared from sera of the 17 patients by affinity chromatography on a DNA cellulose column. Binding to antiendothelial cell antibodies (AECA) and expression of von Willebrand factor (VWF) antigen by cultured human umbilical vein endothelial cells (HUVECs) were studied by flow cytometry.

RESULTS

The percentage of HUVECs binding to AECA or expressing VWF was greater for cells incubated with IgG from patients with SLE than for cells incubated with control IgG, though values did not reach statistical significance; nevertheless, HUVECs incubated with IgG from patients expressed a greater mean fluorescence intensity with AECA (p = 0.0001) and greater VWF expression (p = 0.019). Both the fluorescence intensity and percentage of HUVECs binding to AECA or expressing VWF were significantly greater in HUVEC incubated with IgG containing anti-dsDNA than in those incubated with anti-dsDNA depleted IgG. The concentration of VWF in the supernatant was significantly increased in HUVECs incubated with IgG containing anti-dsDNA compared with control IgG or anti-dsDNA depleted IgG. Pretreatment of HUVECs with native DNA before incubation with IgG from lupus patients did not increase binding to AECA, or expression or release of VWF.

CONCLUSIONS

Our study provides in vitro evidence that antibodies to DNA have a pathogenic role in the induction of inflammatory injury of the vascular endothelium in SLE.

Human T cell responses to autoantibody variable region peptides

The origins and regulation of autoantibodies in SLE may involve idiotypic cell interactions. The purpose of this study was to determine if SLE patients have T cells reactive with the idiotopes of autoantibodies. Sequences of the variable regions of two DNA-binding autoantibodies (V lambda of antibody B3 and VH of 9G4) were selected according to the predicted location of their idiotypes defined previously by anti-idiotypic antibodies. The sequences were prepared as synthetic 16mer peptides (idiopeptides). Peripheral blood mononuclear cells were prepared from SLE patients (n = 28) and controls (n = 13) and put into multiple microcultures with idiopeptide for 6 days. The frequency of responding cultures was determined as those incorporating thymidine at levels above the mean plus three standard deviations of the control cultures lacking peptide. Of the 28 lupus patients, six responded to B3 idiopeptide and five to the 9G4 idiopeptide. Some patients responded to other idiopeptides, but only one normal individual responded to each reference peptide. The difference between the patient and control responses to all idiopeptides was significant by chi 2 analysis (P = 0.025). We conclude that patients with SLE show evidence of sensitisation of T cells to idiotopes of autoantibodies. Such anti-idiotypic T cells could either provide idiotype-specific help or suppression for autoantibody responses in SLE.

Lupus nephritis in childhood and adolescence

Lupus nephritis in childhood usually presents after the age of 10 years, and presentation under 5 years is very rare. More males (F:M ratio 4.5:1) are affected than in adult-onset cases, but the ratio is the same in prepubertal and pubertal children. The incidence of clinically evident renal disease is greater at onset than in adults (82%), the usual presentation being with proteinuria, 50% having a nephrotic syndrome. Half the children show World Health Organisation class IV nephritis in renal biopsies. Neuropsychiatric lupus is present at onset in 30%, may complicate 50% at some point and remains a major problem. Prognosis has improved greatly over the past 30 years, at least in part the result of immunosuppressive treatment. Treatment of the initial phase may be guided by the severity of the renal biopsy appearances, more aggressive treatment including cytotoxic agents, i.v. methylprednisolone and perhaps plasma exchange, although the value of exchange is not established. Controversy persists as to the most effective cytotoxic treatment in the acute phase, both oral and i.v. cyclophosphamide and azathioprine being used in different units. In the chronic maintenance phase it seems established both clinically and histologically that addition of a cytotoxic agent improves outcome, but again the drug and route of administration are contentious. Azathioprine has the advantage of being safe for pregnancy and not gonadotoxic, whilst i.v. cyclophosphamide has been demonstrated to improve results over prednisolone alone in controlled trials and has advantages in non-compliant patients. No trial comparing the two regimes has been carried out, and one is needed. Today children much less commonly go into renal failure, and the main causes of actual death (15% of patients over 10 years) are now infections and extra-renal manifestations of lupus, principally neurological. Morbidity of the disease and the treatment remain a major problem, especially when treatment exacerbates complications of the disease itself, such as infections, osteonecrosis, thrombosis, vascular disease and possibly neoplasia.

Injections of complexes made of dsDNA and specific polyclonal antibodies extend MRL lpr mouse survival: a pilot study

Antibodies towards double-strain (ds) DNA are responsible for the development of lupus nephritis both in human and animal models. A method by which one would suppress the production of pathogenic idiotypes could therefore prevent the development of nephritis. To this end, we prepared polyclonal anti-dsDNA antibodies by immunoaffinity from a serum pool of MRL/MpJ-lpr mice, a strain that develops an early form of nephritis identical to its human counterpart. Antigen-antibody complexes were prepared by addition of dsDNA. Such complexes have the potential of altering the anti-DNA antibody response and boosting the production of specific anti-idiotypic antibodies. Two groups of 14 MRL lpr mice were treated by regular intraperitoneal injections of 10 micrograms dsDNA-anti-dsDNA complexes or carrier buffer, starting at the age of 4 weeks, namely, prior to the appearance of nephritogenic anti-dsDNA IgG antibodies. We show here that such a treatment significantly extended the survival of treated mice compared with the control group. Five treated mice were still alive at month 11 compared with two in the control group. In addition, microscopic kidney examination at the time of death showed less lesions in the treated group compared with controls. This study indicates that complexes made of dsDNA and anti-dsDNA can delay the development of nephritis in the MRL lpr mouse strain.

Beneficial effect of polyclonal immunoglobulins from malaria-infected BALB/c mice on the lupus-like syndrome of (NZB x NZW)F1 mice

We previously reported that infection of BALB/c mice with the parasite Plasmodium chabaudi induces high production of natural autoantibodies. Here we demonstrate that such an infection of lupus-prone (NZB x NZW)F1 (B/W) mice retards the development of their autoimmune disease. Survival and disease hallmarks (high-grade proteinuria and IgG anti-DNA antibodies) were delayed for 6 months when parasite inoculation was given at either 3 or 7 months of age, i.e. before or after the onset of the clinical symptoms. Similar beneficial effects, although less pronounced, were obtained when mice were treated with a total of 800 micrograms of IgG (P-IgG) or IgM (P-IgM) or 300 micrograms of cryoglobulin preparations isolated from P. chabaudi-infected BALB/c mice while similarly prepared fractions from uninfected mice had little effect. Compared to these fractions, P-IgG and P-IgM contained higher levels of natural antibodies bearing the D23 idiotype characteristic of polyreactive natural autoantibodies with enhanced activity against Fab and Fc fragments of IgG. In surviving mice, the level of anti-DNA antibodies, particularly those of IgG1 isotype, were significantly decreased. Flow cytometric analysis of various T cell subsets showed that the number of cells expressing gamma delta T cell receptor (TcR) antigens which did not vary with age was not modified after P-IgG or P-IgM treatment. In contrast, the number of T cells expressing V beta 8.1,2,V beta 10 and V beta 14 TcR antigens, which increased with age, were significantly reduced. Taken together, these results indicate that parasite infection of mice induces the synthesis of populations of IgM and IgG natural autoantibodies with immunoregulatory properties and that these antibodies attempt, at least transitorily, to rescue a natural autoantibody network that is deficient in B/W mice.

Inhibition of autoantibody production in experimental SLE by pre-immunization with DNA

Experimental SLE can be induced in susceptible mice by their immunization with the human monoclonal anti-DNA antibody that bears a major idiotype-16/6 Id. The SLE afflicted mice produce a variety of autoantibodies including anti-DNA antibodies. It was of interest to find out the effect of DNA on the induction of the experimental disease. To this end, mice were immunized with combinations of 16/6 Id and DNA. The results indicated that whereas mice primed with 16/6 Id developed high titers of antibodies to the 16/6 Id and a variety of autoantibodies typical to the experimental SLE, preimmunization of mice with ssDNA led to a reduction in the 16/6 Id specific antibodies and in the autoantibody titers. No significant differences could be detected in the clinical manifestations which are present in the mice with experimental disease (increased erythrocyte sedimentation rate, leukopenia, proteinuria and glomerular immune complex deposition) in all mice immunized with 16/6 Id including those pretreated with DNA. Thus, no direct correlation exists between the autoantibody levels and the clinical pathology, and probably other factors are involved in the development of the experimental disease.

Preferential adsorption of cationic anti-DNA antibodies with immobilized polyanionic compounds, dextran sulfate

It has been shown that cationic anti-DNA antibodies have nephritogenic potential in murine models of lupus nephritis. More recently, we have reported that there is a close relationship between the presence of circulating cationic anti-DNA antibodies and the development of lupus nephritis in humans, and that the cationic anti-DNA antibodies bind to heparan sulfate, a major glycosaminoglycan in glomerular basement membrane, much better than neutral anti-DNA antibodies. This suggests that cationic anti-DNA antibodies of the IgG class may be responsible for development of nephritis in vivo in patients with systemic lupus erythematosus. In this study, we first studied reactivity of anti-DNA antibodies with a panel of glycosaminoglycans in vitro using ELISA methods, and found that anti-DNA antibodies cross-react with dextran sulfate, hyaluronic acid and chrondroitin sulfate. The reactivity and selectivity of dextran sulfate with anti-DNA antibodies was confirmed by in vitro immunoadsorption of the patient's sera with dextran sulfate-fixed column; incubation of auto-antibody-positive sera with dextran sulfate cellulose column removed anti-DNA, but not anti-RNP, anti-Sm, anti-SSA and anti-SSB antibodies from the sera in vitro. Of note is that dextran sulfate cellulose column absorbed exclusively, if not all, cationic anti-DNA antibodies in their sera. Nonspecific binding of total immunoglobulins as well as total proteins to the column was marginal. It has been suggested that cationic anti-DNA antibodies in sera of patients with refractory lupus nephritis could be efficiently removed by apheresis using dextran sulfate column.

Structural aspects of recognition motifs contributing to autoimmune responses

Sequence analysis of autoimmune-associated antibodies has suggested a structural relatedness between genes used to encode autoantibodies and those encoding unrelated antibodies without autoreactive specificities. Subsequently, the basis for cross-reactive idiotypes across germ-line lineages, as well as conserved interspecies cross-reactivities of autoantigens among serologically similar antibodies, may result from evolutionary duplication of particular types of recognition motifs. As a first step toward elucidating structural recognition principles underlying possible cross-reactive epitopes involved in autoimmune pathologies, structural features of selected motifs associated with native ligand binding are examined for their inherent occurrence in antibody and T-cell receptor repertoires. This analysis considers the putative recognition features representative of common motif subsets shared with loop structures in CDR2 and FR3 regions of antibodies such as charge-2x-charge-x-charge or hydrogen bond donor (acceptor)-2x-charge-x-hydrogen bond donor (acceptor) type motifs, where x is any residue that can participate in maintaining a loop conformation. Such tracts encoded in the CRD2 and FR3 regions of heavy chains of antibodies and T-cell receptors (TCRs) associated with autoimmune dysfunction, with non-autoreactive antibodies, and with native host proteins. Such evolutionarily conserved motifs may be targets for complementary interactions involving autoantibodies and receptors.

Expression of the major rheumatoid factor cross-reactive idiotype in pediatric patients with systemic lupus erythematosus

Rheumatoid factor cross-reactive idiotype (RF-CRI) is expressed in high concentrations in the sera of some patients with rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA). To determine if RF-CRI is specifically expressed in rheumatic disease or if it is secondary to polyclonal B-cell activation, we examined sera of 23 children with SLE, 16 adolescents with infectious mononucleosis (IM), and age-matched pediatric controls for RF-CRI expression. Concentrations of RF-CRI in serum, determined by an inhibition ELISA, were 24 +/- 17 micrograms/ml (mean +/- SD) in 25 normal children, 31 +/- 17 in 16 young adults with IM, and were significantly increased, 70 +/- 80 micrograms/ml, in the 23 children with SLE (p less than 0.036). Eleven of 23 SLE patients had serum RF-CRI greater than the mean +/- 2 SD for normal children. Ten of 23 SLE sera contained IgM rheumatoid factor (RF) activity. One patient with IM had a borderline elevated RF-CRI level, and 5 IM patients had RF in their sera. The serum IgM concentrations in sera were: SLE (192 +/- 93 mg/dl) and IM (234 +/- 77 mg/dl) sera. These levels were significantly elevated compared to controls (132 +/- 44 mg/dl), p less than 0.031 for SLE and p less than 0.001 for IM, suggesting that polyclonal activation of B cells was present in SLE and IM patient groups. Increased expression of RF-CRI in the SLE patients correlated directly with high titer anti-DNA antibody values (r = 0.3965, p less than 0.05) and RF activity when human IgG (r = 0.5026, p less than 0.05) was used as the RF binding substrate and inversely with serum C3 levels (r = 0.3925, p less than 0.05). RF-CRI expression did not correlate with RF that bound rabbit (r = 0.3123, p greater than 0.05). Increased serum RF-CRI expression is not a result of polyclonal B-cell activation. RF-CRI may be selectively up-regulated in patients with SLE.

Evidence for regulation of naturally activated autoreactive B cells

A large fraction of naturally activated B cells in the neonate displays degenerate specificity, including reactivity with autoantigens. Transgenic mouse models of autoreactive B cells are mainly concerned with monospecific B cells of high avidity, and the fate of naturally activated autoreactive B cells is still a matter of debate. To pursue this question further, we chose an IgM autoantibody with a recurrent idiotype (Id), i.e. Sp6, because transgenic mice expressing this IgM also were available. In a first approach monoclonal antibodies (mAb) derived from untreated, antigenically stimulated and transgenic mice were used to test whether there were indications for deletion or for Id regulation of naturally activated autoreactive B cells. Over 90% of thymus and spleen cell derived hybridomas from 6-day-old Sp6-transgenic mice were trinitrophenyl (TNP) reactive, carried the Sp6-Id and bound to a panel of self antigens, including mouse albumin. We failed to obtain B cell hybridomas from the thymus of 28-day-old Sp6-transgenic mice. Furthermore, we could not detect any mAb carrying an anti-Sp6 Id, but Sp6 did weakly bind to itself. About 25% of mAb derived from control mice displayed degenerate specificity, the majority of them also were TNP reactive. The Sp6 Id was found at a low frequency and a comparable number of mAb carried an anti-Sp6 Id. Prenatal manipulation at the antigen level (trinitrobenzenesulfonic acid treatment) led to a transient expansion of TNP- and autoreactive mAb. The number of mAb carrying the Sp6 Id was not increased, but mAb carrying an anti-Sp6 Id were observed at high frequency. Those mAb also displayed degenerate specificity. Since Sp6-transgenic mice were perfectly healthy, it is concluded that this particular autoreactive antibody of degenerate specificity cannot be harmful for the developing organism, which may possibly be due to its self-binding capacity. Furthermore, some process of down-regulation was indicated by the absence of B cells expressing the transgene in the thymus of young adult mice. Autoreactivity of untreated and prenatally antigen-treated mice was, in addition, regulated at the Id level. In particular, mAb recognizing the Id of Sp6 were significantly expanded in antigenically stimulated mice. The data were interpreted in the sense that autoreactive B cells appearing early during ontogeny were rather strictly controlled either by (functional) clonal deletion or by idiotypic connectivity.

Anti-idiotype and immunosuppressant treatment of murine lupus

The effect of the administration of a xenogeneic anti-idiotype antibody (anti-Id33) to a cross-reactive idiotype (Id33) present on anti-dsDNA antibody was examined in 6-week-old (NZB/NZW) F1 (BWF1) female mice. The administration of anti-Id33 led to a transient reduction in immunoglobulins expressing Id33, followed by a rise at 30 and 34 weeks that was significantly higher than in untreated mice (P less than 0.05). Likewise, anti-dsDNA antibody levels were significantly higher at 10 and 18 weeks than in untreated mice (P less than 0.01). No differences were seen in survival to 40 weeks, proteinuria or the severity of glomerulonephritis. Concurrent administration of cyclosporin A (CyA) with anti-Id33 markedly ameliorated glomerular injury and proteinuria and improved survival. By contrast, glomerular injury, proteinuria and survival were worse in mice treated with cyclophosphamide plus anti-Id33, compared with untreated mice. Neither CyA nor cyclophosphamide treatment, when given with anti-Id33 altered serum levels of anti-dsDNA, anti-ssDNA or Id33+ immunoglobin, compared with untreated mice. The different effects of CyA and cyclophosphamide on T lymphocytes and their discrepant effects on glomerular injury when given with anti-Id33 in this model lead us to postulate a role for T lymphocytes in the glomerular injury of BWF1 lupus.

Comparison of DNA antibody idiotypes in human sera: an international collaborative study of 19 idiotypes from 11 different laboratories

The distribution of and relationships between 18 anti-DNA antibody idiotypes and one anti-acetylcholine receptor antibody idiotype have been tested in an international collaborative study of human sera from 180 individuals. The main finding is that the serum levels of many of these idiotypes, whether of murine or human origin, show a high degree of statistical correlation. The studies in a wide range of autoimmune rheumatic diseases confirm that none of the idiotypes tested is disease specific, but 13 of 15 (87%) whose levels were recorded as OD units or cpm correlated strongly with anti-ssDNA antibody levels and 11 of 15 (73%) with total serum IgM. Expression of several idiotypes was found to fluctuate in parallel with disease activity in SLE; levels of others were also elevated in the healthy relatives of lupus patients whilst a few were also raised in the spouses of these patients. The data support the notion that there may be only a few groups of related DNA antibody idiotypes. The correlations between the idiotypes with regard to their quantities, association with disease activity, and wide distribution in different diseases and healthy individuals suggest at least two explanations. First, all of these idiotypes may be present in normal immunoglobulin repertoires and simply increase in response to poly- or oligoclonal B-cell activation in autoimmune diseases. Secondly, these idiotypes may be structurally linked to each other, so that their behaviour under conditions of specific antigenic stimulation is similar. Genetic and structural studies will be required to distinguish between these possibilities.

The genetic regulation of the induction of experimental SLE

We have recently reported the induction of systemic lupus erythematosus (SLE) in C3H.SW female mice by their immunization with a human monoclonal anti-DNA antibody that bears a common idiotype termed 16/6 Id. In the present study, the ability to induce experimental SLE in seven inbred mouse strains by immunization with the 16/6 Id was examined. Two out of the seven strains failed to develop the disease. These two strains did not produce antibodies specific to the 16/6 Id, while the other five strains produced high titres of anti-16/6 Id antibodies. The anti-16/6 Id antibody response, followed by the induction of the disease, was not found to be MHC or Ig heavy chain allotype linked. F1 hybrids between a resistant strain and two of the susceptible strains were found to be resistant to the induction of the disease, indicating that susceptibility is inherited as a recessive trait. In the autoimmune NZB/W F1 female mice, immunization with the 16/6 Id resulted in an early onset of the SLE-like disease. The results of the present study indicate the role of the anti-16/6 Id antibodies in the induction of experimental SLE, and provide direct evidence for the importance of the genetic background in determining susceptibility to SLE.

Structural characteristics of the variable regions of immunoglobulin genes encoding a pathogenic autoantibody in murine lupus

We have studied several monoclonal anti-double-stranded (ds) DNA antibodies for their ability to accelerate lupus nephritis in young NZB X NZW F1 female mice and to induce it in BALB/c mice. Two identified as pathogens in both strains have characteristics previously associated with nephritogenicity: expression of IgG2a isotype and IdGN2 idiotype. Both pathogenic antibodies used the combination of genes from the VHJ558 and VK9 subfamilies. Two weak pathogens failed to accelerate nephritis in young BW mice, but induced lupus nephritis in BALB/c mice. They both express IdGN2; one is cationic and an IgG3, the other is an IgG2a. Additional MAbs (some IgG2a, one IdGN2-positive) did not accelerate or induce nephritis. We have cloned and sequenced the variable regions of the immunoglobulin genes of one pathogenic autoantibody. No unique V, D, or J gene segments and no evidence of unusual mechanisms in generating diversity were used to construct this antibody. These data argue against use of unique abnormal Ig genes by systemic lupus erythematosus individuals to construct pathogenic autoantibody subsets. Instead, the major abnormality may be immunoregulatory.

DNA antibody idiotypes: an analysis of their clinical connections and origins

Approximately thirty common DNA antibody idiotypes have been described on hybridoma derived or affinity purified DNA-binding antibodies. There are associations between some idiotypes and the clinical manifestations of systemic lupus erythematosus although none are sufficiently firm to be clinically useful in identifying subsets of SLE or in assessing disease activity in individual patients. The expression of these idiotypes is not confined to DNA antibodies in SLE. They may be found in the serum from patients with a range of autoimmune rheumatic disorders, infectious disease and blood dyscrasias. In most cases the antigen binding specificity of the antibody bearing the idiotype is unknown. The precise relationship between the various idiotypes is becoming better understood with increasing availability of genetic and structural data. DNA antibody idiotype manipulation may provide a potential new therapeutic modality in SLE.

The treatment of lupus nephritis

The literature on the treatment of lupus nephritis is scattered, much of it in rheumatological rather than nephrological journals. Whatever our ignorance of the nature and genesis of lupus nephritis, under empirical treatment the prognosis, especially for severe forms, has improved dramatically during the past 20 years. For severe lupus nephritis, the evidence that the addition of cytotoxic agents to corticosteroids improves outcome is now secure, and discussion centres mainly on which drug to use and by what route. Intravenous methylprednisolone is at least as effective as high-dose tapering oral therapy for initial treatment, and carries fewer side-effects. The role of plasma exchange in lupus remains undefined: it may have a role in the treatment of cerebral manifestations or otherwise resistant patients, but controlled trials have failed to show benefit. Future developments will probably centre around the use of specific monoclonal antibodies which target specific groups and subgroups of cells, "humanised" by the splicing of human Fc piece to rodent (fab)2, perhaps bearing toxins. To use these agents to best advantage, however, we will have to understand better than we do today the nature of the cellular defects in the immune response which underlie the lupus syndrome.

The role of the idiotypic network in the induction of experimental systemic lupus erythematosus

Systemic lupus erythematosus (SLE) has been induced in C3H.SW mice by their immunization with a human monoclonal anti-DNA antibody that bears a common idiotype-16/6 Id. Following immunization, high levels of murine anti-16/6 and anti-anti-16/6 antibodies were detected in the sera of the immunized mice. Elevated titers of autoantibodies reacting with ssDNA, dsDNA, poly(I), poly(G), RNP, Ro, and La were also observed. The serological findings were associated with significant proteinuria, leukopenia, and elevated erythrocyte sedimentation rate. Immune complex deposition in the glomerular mesangium and sclerosis of the glomeruli were demonstrated. To study whether or not anti-idiotype antibodies are involved in the induction of the disease, a murine monoclonal antibody against the 16/6 Id was prepared and injected into C3H.SW mice. The anti-16/6 Id antibody induced experimental SLE similarly to the 16/6 Id with an accelerated kidney pathology. A study performed on different mouse strains indicated that the susceptibility to the induction of SLE by the 16/6 Id is strain dependent and directly correlates to their ability to produce anti-16/6 Id specific antibodies.

The role of anti-idiotypic antibodies in the induction of experimental systemic lupus erythematosus in mice

We have recently reported the induction of experimental systemic lupus erythematosus (SLE) in mice by a human anti-DNA monoclonal antibody (mAb) that bears a common idiotype, the 16/6 Id. In the present report we investigated the role of the idiotypic network in the induction of experimental SLE by using a murine anti-idiotypic mAb specific for the 16/6 Id. This anti-idiotypic mAb induced experimental SLE similarly to the 16/6 Id. Thus, following immunization, in addition to 16/6 Id+ antibodies, the mice produced antibodies to various nuclear antigens: single-stranded DNA, double-stranded DNA, poly(I), poly(G), Ro, La, Sm and ribonucleoproteins. Similarly to the 16/6 Id-immunized mice, the mice injected with the anti-16/6 Id mAb exhibited elevated erythrocyte sedimentation rate and leukopenia. The murine anti-16/6 Id mAb was found to be more effective than the 16/6 Id, in causing earlier onset of proteinuria and renal damage. These results suggest that the idiotypic network and particularly anti-idiotypic antibodies specific for anti-DNA common idiotypes found in SLE, play an important role in the induction of SLE in mice.

Suppression of malaria-induced autoimmunity by immunization with cryoglobulins

Cryoglobulins obtained from malaria-infected (Plasmodium berghei berghei) Balb/c mice were administered intraperitoneally to naive Balb/c mice. Ten days or 9 months following cryoglobulin administration, the naive mice were infected with malaria. Comparison of sera from cryoglobulin-treated malaria-infected mice with sera from control infected mice revealed that pretreatment with cryoglobulins resulted in (1) reduced levels of circulating immune complexes; (2) reduced levels of autoantibodies reactive with nuclear and cytoplasmic antigens; and (3) suppressed development of cryoglobulinemia. Furthermore, the effect of cryoglobulins was long lasting, suggesting that recipient mice may have been actively immunized against autoantibody production.

Systemic lupus erythematosus

Systemic lupus erythematosus is a common disease--studies throughout the world broadly agree on a prevalence of 1 in 1000 women. Recently an important clinical advance has come from the description of a syndrome of recurrent thrombosis, recurrent abortion and neurological disease associated with antiphospholipid antibodies. The discovery that immunological mechanisms may apply in some cases of thrombosis has led to new insights into the aetiology and treatment of vascular disease in general.

A monoclonal DNA-binding autoantibody causes a deterioration in renal function in MRL mice with lupus disease

Two DNA-binding monoclonal antibodies (MoAb) derived from lupus mice were examined for their effects on kidney function. Antibody IV-228, reactive with single-stranded DNA (ssDNA) but not double-stranded DNA (dsDNA) significantly altered kidney function in some MRL/Mp-lpr/lpr (MRL/lpr) mice with lupus glomerulonephritis. Antibody II-410, preferentially reactive with dsDNA, did not modify kidney function in MRL/lpr mice. Neither antibody affected normal healthy MRL/Mp- +/+ (MRL/n) mice. Not all MRL/lpr mice were equally affected by IV-228 and in some animals with clinical disease it was without effect even when high circulating antibody levels were maintained by five sequential daily injections. Its affects upon kidney function appeared to be related to its ability to localize in vivo in glomeruli. It is assumed that epitopes on trapped immune complexes are immunologically available to circulating antibodies, and in those animals where injected antibody is not captured this is because the antigen epitope is either absent or is masked by the animals' own auto-antibodies. We conclude that antibodies which bind to ssDNA contribute to lupus nephritis; that individual mice make DNA-binding antibodies of different fine specificity; and that kidney disease is not always due to the same balance of antibodies in members of a genetically homogeneous stock.

Clonotypic heterogeneity in experimental interstitial nephritis. Restricted specificity of the anti-tubular basement membrane B cell repertoire is associated with a disease-modifying crossreactive idiotype

Experimental anti-tubular basement membrane (anti-TBM) disease is an autoimmune interstitial nephritis elicited in susceptible rodents after immunization with renal tubular antigen. The nephritogenic antigen in the immunizing preparation is 3M-1, a 48,000 Mr noncollagenous glycoprotein. The hallmarks of the renal lesion are the presence of anti-TBM antibodies (anti-TBM-Ab) and a dense mononuclear cell infiltrate. The anti-TBM B cell repertoire in this disease was analyzed using a library of 22 anti-TBM mAbs generated in a prototypically susceptible Brown Norway rat. These anti-TBM mAbs were all demonstrated to be 3M-1 specific and their characterization formed the basis for the following observations: (a) The size of the anti-TBM B cell population is estimated at 58 distinct clones; (b) by competitive inhibition criteria, all anti-TBM mAbs recognize the same (or spatially close) epitope(s) on 3M-1. This focused recognition was maintained in spite of considerable variability in affinity. Epitopic dominance could also be demonstrated in human polyclonal anti-TBM antisera from a patient with anti-TBM disease; and (c) a crossreactive idiotype was documented, and antisera directed toward this set of variable region determinants was shown to be effective as a prophylactic regimen to abrogate disease, and as a therapeutic modality to arrest the progression of disease; (d) analysis of VH gene families suggested biased usage of Q52- and 7183-like families, although at least three gene families are used in the anti-TBM-Ab response. Thus, the anti-TBM B cell compartment in BN rats is moderately large, but is primarily focused to a single epitope on the nephritogenic antigen and is associated with a disease-modifying crossreactive idiotype.

Induction of a systemic lupus erythematosus-like disease in mice by a common human anti-DNA idiotype

Systemic lupus erythematosus (SLE) is considered to be the quintessential autoimmune disease. It has not been possible to induce SLE in animal models by DNA immunization or by challenge with anti-DNA antibodies. We herewith report a murine model of SLE-like disease induced by immunization of C3H.SW female mice with a common human monoclonal anti-DNA idiotype (16/6 idiotype). Following a booster injection with the 16/6 idiotype, high levels of murine anti-16/6 and anti-anti-16/6 antibodies (associated with anti-DNA activity) were detected in the sera of the immunized mice. Elevated titers of autoantibodies reacting with DNA, poly(I), poly(dT), ribonucleoprotein, autoantigens [Sm, SS-A (Ro), and SS-B (La)], and cardiolipin were noted. The serological findings were associated with increased erythrocyte sedimentation rate, leukopenia, proteinuria, immune complex deposition in the glomerular mesangium, and sclerosis of the glomeruli. The immune complexes in the kidneys were shown to contain the 16/6 idiotype. This experimental SLE-like model may be used to elucidate the mechanisms underlying SLE.

Idiotypic spreading promotes the production of pathogenic autoantibodies

We propose that a major immunoregulatory abnormality in murine and human autoantibody-mediated disease is idiotypic spreading. By this mechanism, B cells with the genetic information to produce immunoglobulin (Ig) bearing certain public idiotypes (Ids) are selectively upregulated, probably by Id-recognizing helper T cells. The model in which we are testing the hypothesis is systemic lupus erythematosus (SLE) in humans and NZB/NZW F1 (BW) female mice. Recent experiments have shown that the number of public Ids expressed on the Ig of nephritic BW mice is quite restricted. IdX is the dominant Id on serum Ig; IdGN1 and IdGN2 are also common. All three Ids were initially derived from spontaneous antibodies to DNA. Together the three are present on 85% of the total Ig repertoire. Such restriction suggests idiotypic spreading. In glomerular Ig deposits from nephritic BW mice, IdGN1 and IdGN2 are found on 45% of the total Ig: IdX is present in minute amounts. Furthermore, suppression of IdGNs by administration of anti-IdGN1 to BW mice resulted in significant delay in the onset of nephritis, but the IdGNs escaped from control and eventually caused a fatal nephritis. Finally, studies of glomerular Ig deposits in renal biopsies of patients with SLE have shown that IdGN2 dominates such Ig, being present in 76% of renal biopsies from SLE patients and in 6% from patients with non-lupus immune nephritis. Therefore, we have concluded that IdGN1 and IdGN2 are markers of nephritogenic subsets of autoantibodies and are probably the products of idiotypic spreading most likely to cause disease. Finally, after a review of recent experiments suggesting the dominance of autoreactive, Mossman Type 2 T helper cells in nephritic BW mice, it is hypothesized that autoreactive, IdGN-recognizing helper T cells may be central to the sustained upregulation of pathogenic autoantibodies in murine and human SLE.

An idiotope-specific autoantibody in SLE

The public idiotype Id-16/6 and the public idiotope Id-LLa were originally defined on the same human monoclonal anti-DNA antibody, but they are also known to occur separately on other anti-DNA antibodies. We sought the presence of these immunoglobulin variable region markers in purified immunoglobulins from the serum of nine patients with systemic lupus erythematosus (SLE) and 33 healthy donors. Sera from five patients were positive for Id-16/6, and five were positive for Id-LLa. The immunoglobulin preparations were passed over a Sepharose-Id-16/6 column in order to recover auto-anti-idiotypes. An eluate of that column was obtained from the immunoglobulin preparation of one patient whose serum was Id-16/6+ and Id-LLa-. This eluate was shown by competition assay to bind to IdLLa. This is the first demonstration of spontaneously arising human auto-anti-idiotypes against a specific idiotypic system in SLE. The results suggest that antibodies against the Id-LLa idiotope may play a role in immunoregulation.

Suppression of anti-DNA antibody production in MRL mice by treatment with anti-idiotypic antibodies

Antibodies against idiotypic determinants carried by a monoclonal polyspecific natural autoantibody were raised in rabbits and in syngeneic BALB/c mice. These anti-idiotypic antibodies were administered to newborn and to pregnant BALB/c mice and to MRL-lpr/lpr mice. Serial measurements of the idiotypes, naturally occurring autoantibodies, and antibodies obtained after antigenic stimulation were performed in the sera of the injected mice and in the offspring of pregnant mice. No idiotypic suppression was noted in newborn injected mice. Transient suppression of idiotypes recognized by the syngeneic anti-idiotypic antibody was noted in the offspring of pregnant mice injected with the rabbit polyclonal anti-idiotypic antiserum. No changes in naturally occurring autoantibodies or in antibodies appearing after antigenic stimulation were noted in BALB/c mice. In contrast, a significant decrease of spontaneously occurring anti-DNA antibodies was found in MRL-lpr/lpr mice treated with rabbit polyclonal anti-idiotypic antiserum. Furthermore in these mice a slight decrease of anti-TNP antibodies was also observed. These results suggest that anti-idiotypic antibodies directed against natural autoantibodies may play a regulatory role in the immune system; this role is more easily appreciated in mice suffering from immune dysregulation.

Polyclonal B-cell activation after intravenous immunoglobulin therapy in idiopathic thrombocytopenic purpura--an anti-idiotype response?

Polyclonal B cell activation occurred in 3 patients following treatment with intravenous immunoglobulin (i.v. Ig) for idiopathic thrombocytopenic purpura (ITP). The possibility that this may represent an anti-idiotype response and the hypothesis that prolonged remission of ITP may be induced by this mechanism are discussed.

Ligand-binding and idiotypic cross-reactions between anti-DNA antibodies and antibodies to Klebsiella K30 polysaccharide in patients with systemic lupus erythematosus or rheumatoid arthritis

Antibodies to DNA and K30p were purified by affinity procedures and tested for their ability to cross-react with K30p and DNA, respectively. Anti-ssDNA antibodies were shown to react with solid-phase K30p and be inhibited in a dose-dependent manner by soluble ssDNA and K30p. Conversely, anti-K30p antibodies were found to bind immobilized ssDNA and be inhibited with soluble inhibitor. These results show that certain subpopulations of anti-ssDNA and anti-K30p antibodies overlap in their ligand-binding specificities. Idiotypic (Id) analysis showed that anti-K30p antibodies did not react significantly with an anti-Id reagent directed against a common anti-DNA framework Id (AM Id), thus clearly separating K30p-binding anti-DNA antibodies into an AM Id-negative population. When anti-DNA antibodies were probed with an anti-Id reagent directed against a framework Id present on anti-K30p antibodies (SP Id), substantial reactivity was found. Thus the SP Id identifies a subpopulation of antibodies capable of binding both K30p and DNA. These results show that a subset of anti-ssDNA antibodies cross-react with K30p antigen and are idiotypically related to a subset of antibodies reactive with K30p.

Increased synthesis of poly(ADP-ribose) in isolated liver nuclei from autoimmune NZB/NZW mice

The synthesis and degradation of poly(ADP-ribose) were investigated in isolated liver nuclei from autoimmune NZB/W mice and four strains of normal mice. Compared to normal mice the maximum levels of incorporation of [3H]NAD into poly(ADP-ribose) were increased about 2-fold in the autoimmune mice. The kinetics of incorporation suggested that this change was due to an increase in the activity of the polymerase rather than a decrease in the level of degradative enzymes. Thus there may be a connection between autoimmunity and poly(ADP-ribose) metabolism.

The contribution of NZW genes to lupus-like disease in (NZB x NZW)F1 mice

Unlike parental NZB or NZW mice, (NZB X NZW)F1 mice exhibit a lupus-like disease characterized by high serum levels of IgG antinuclear antibodies and a fatal immune-complex glomerulonephritis. At least three unlinked gene loci can be distinguished in NZW mice that conceivably contribute to a T cell-dependent autoimmune disease, including the MHC (H-2z) and the T cell receptor alpha and beta chain gene complexes. We undertook an (NZB X NZW)F1 X NZB backcross to determine the relative contribution of these NZW genes to lupus-like renal disease and autoantibody production in F1 mice. The incidence of severe renal disease and elevated levels of IgG antibodies to dsDNA and histone in the backcross mice was approximately half of that observed in (NZB X NZW)F1 mice. Furthermore, there was a strong correlation between the presence of the NZW H-2z haplotype and lupus-like disease in backcross mice. Approximately 90% of backcross mice with disease carried the NZW H-2z locus compared with 16% of mice without disease; nearly 90% of H-2d/z mice expressed severe autoimmune disease. In contrast, no association was apparent between the presence of the NZW T cell receptor alpha chain gene complex or beta chain gene complex and severe renal disease or autoantibody production. Thus, the NZW MHC or gene(s) linked to this locus appear to be the only dominant NZW genetic contribution to F1 disease.

DNA antibody idiotypes: a review of their genetic, clinical, and immunopathologic features

The initial studies of anti-DNA antibody idiotypes we performed, along with those of our colleagues and other groups, focused on the narrow question of their relevance to lupus autoantibodies. The subsequent studies in this report have forced us to examine a much broader range of issues. It is evident that despite the great advances in understanding the structure and function of antibodies, lymphocytes, and receptors, our knowledge of many fundamental elements in autoimmune disease is woefully incomplete. We are still unsure whether the germ line gene sequences controlling antibody production have evolved solely in response to exposure to new foreign antigens. Alternatively, these antibodies (and the idiotypes they bear) may have developed largely in response to changes in the internal environment. Superficially, it can be argued that "self reactivity" associated with the clinical expression of a disease results from a combination of immunologic, genetic, hormonal, and environmental elements. For example, the expression of the 16/6 Id in an appropriate setting may have pathogenetic consequences for some individuals. However, our knowledge of the precise sequence of events that result in devastating disease for some but minimal disease for others is just one of the remaining mysteries.

A monoclonal anti-double stranded DNA antibody from an autoimmune MRL/Mp-lpr/lpr mouse: specificity and idiotype in serum immunoglobulins

Anti-double stranded (ds) DNA antibodies in the sera of lupus-prone MRL/Mp-lpr/lpr (MRL/l) mice were determined by an enzyme-linked immunosorbent assay in parallel with anti-single stranded (ss) DNA, anti-left-handed Z-DNA and anti-poly(ADP-ribose) antibodies. The serum levels of these antibodies in these mice increased with age, and in particular anti-dsDNA antibodies appeared in mice more than 14 weeks old, along with progressive lymphadenopathy. We therefore established a hybridoma producing monoclonal anti-dsDNA antibody (2C10) from an 8-month-old MRL/l mouse. Monoclonal antibody 2C10 did not react with either poly(dT) or poly(I), which are major cross-reactants with previously reported monoclonal MRL mouse autoantibodies. Antibody 2C10 showed preference for phi X-174 replicative form DNA and calf thymus dsDNA over ssDNA. 2C10 idiotype (Id) was present in the sera of MRL/l mice, but only occasionally at high levels even in the aged mice tested. This result suggested that many Ids with anti-dsDNA antibody activity may contribute to lupus pathogenesis in this strain of mouse.

Prevention of lupus diseases in MRL/1, NZBxNZW, and BXSB mice treated with a cyclophosphazene derived drug

A polyclonal activation of lymphocytes (PA) has been suggested to play a pathogenic role in autoimmune and immune complex diseases, particularly in mouse lupus. "DIAM 4," a cyclophosphazene derived drug, selected on the basis of its ability to modulate a PA has been used to treat female MRL/1, female NZBxNZW, and male BXSB mice. In these three strains of mice, the treatment was found to induce an inhibition of the PA, to prevent the increase of anti-DNA antibody levels and the simultaneous decrease of C3 levels, to prevent the appearance of proteinuria, the deposition of immune complexes in glomeruli, and the development of kidney lesions. Moreover in MRL/1 mice, lymphoproliferation was prevented. These results suggest that drugs able to modulate a PA might be efficient in the treatment of mouse lupus nephritis. Such a principle of immunomodulation might open the way to new possibilities of treatment of lupus and other immune complex diseases.

Origins of pathogenic anti-DNA idiotypes in the NZB X SWR model of lupus nephritis

The investigations with the NZB X SWR model show that the development of systemic autoimmune disease is a multistep, multigene process. Severe lupus nephritis in the NZB X SWR hybrids results from the interaction of genes inherited from both the autoimmune NZB and the normal SWR parents. A similar genetic interaction occurs in the NZB X NZW hybrids, but in this model, both the parental strains are abnormal and the nature of the gene products or their mechanism of action is unknown. In the NZB X SWR model, we have been able to identify a restricted subpopulation of nephritogenic anti-DNA antibody idiotypes that are encoded by genes of the normal SWR parents. Thus, these are one set of genes that determine the development of severe lupus nephritis in the F1 hybrids. In addition, another set of genes allows for the expansion of B cells that produce such pathogenic anti-DNA idiotypes in the F1 hybrids since such B-cell clones remain dormant in the normal SWR parents. The latter category of genes, presumably specifying defects in immunoregulation, are probably inherited from the NZB parents or may be the result of complementation of genes inherited from both parents. Further investigations with the NZB X SWR model will help us define the immunoregulatory defects in SLE that are specific for the T and B cells involved in pathogenic autoantibody production.