Antibodies to DNA--towards an understanding of their origin and pathophysiological impact in systemic lupus erythematosus

Antibodies specific for nucleic acid modifications

Nucleotide modifications constitute marks in RNA and DNA that contribute to gene regulation, development and other cellular processes. The understanding of their intricate molecular roles has been hampered by the high number of different modifications, the lack of effective methods and tools for their detection and quantification as well as by their complex structure-function relationship. The recent development of RNA and DNA immunoprecipitation followed by high-throughput sequencing (RIP- and DIP-seq) initiated detailed transcriptome- and genome-wide studies. Both techniques depend on highly specific and sensitive antibodies to specifically enrich the targeted modified nucleotides without background or potential biases. Here, we review the challenges and developments when generating and validating antibodies targeting modified nucleotides. We discuss antibody-antigen interactions, different strategies of antigen generation and compare different binder formats suitable for state-of-the-art high resolution mapping and imaging technologies.

Alpha-actinin-binding antibodies in relation to systemic lupus erythematosus and lupus nephritis

This study investigated the overall clinical impact of anti-α-actinin antibodies in patients with pre-selected autoimmune diseases and in a random group of anti-nuclear antibody (ANA)-positive individuals. The relation of anti-α-actinin antibodies with lupus nephritis and anti-double-stranded DNA (anti-dsDNA) antibodies represented a particular focus for the study. Using a cross-sectional design, the presence of antibodies to α-actinin was studied in selected groups, classified according to the relevant American College of Rheumatology classification criteria for systemic lupus erythematosus (SLE) (n = 99), rheumatoid arthritis (RA) (n = 68), Wegener's granulomatosis (WG) (n = 85), and fibromyalgia (FM) (n = 29), and in a random group of ANA-positive individuals (n = 142). Renal disease was defined as (increased) proteinuria with haematuria or presence of cellular casts. Sera from SLE, RA, and Sjøgren's syndrome (SS) patients had significantly higher levels of anti-α-actinin antibodies than the other patient groups. Using the geometric mean (± 2 standard deviations) in FM patients as the upper cutoff, 20% of SLE patients, 12% of RA patients, 4% of SS patients, and none of the WG patients were positive for anti-α-actinin antibodies. Within the SLE cohort, anti-α-actinin antibody levels were higher in patients with renal flares (p = 0.02) and correlated independently with anti-dsDNA antibody levels by enzyme-linked immunosorbent assay (p < 0.007) but not with other disease features. In the random ANA group, 14 individuals had anti-α-actinin antibodies. Of these, 36% had SLE, while 64% suffered from other, mostly autoimmune, disorders. Antibodies binding to α-actinin were detected in 20% of SLE patients but were not specific for SLE. They correlate with anti-dsDNA antibody levels, implying in vitro cross-reactivity of anti-dsDNA antibodies, which may explain the observed association with renal disease in SLE.

Immunity and autoimmunity induced by polyomaviruses: clinical, experimental and theoretical aspects

In this chapter, polyomaviruses will be presented in an immunological context. Principal observations will be discussed to elucidate humoral and cellular immune responses to different species of the polyomaviruses and to individual viral structural and regulatory proteins. The role of immune responses towards the viruses or their proteins in context of protection against polyomavirus induced tumors will be described. One central aspect of this presentation is the ability of polyomaviruses, and particularly large T-antigen, to terminate immunological tolerance to nucleosomes, DNA and histones. Thus, in the present chapter we will focus on clinical, experimental and theoretical aspects of the immunity to polyomaviruses.

Prior anti-dsDNA antibody status does not predict later disease manifestations in systemic lupus erythematosus

OBJECTIVES

To determine if the past presence of anti-double-strand (ds)DNA antibody (Ab) will predict subsequent disease activity in patients with systemic lupus erythematosus (SLE).

METHODS

A longitudinal study of clinical and serological disease manifestations registered during 2,412 patient months of follow-up in a well-defined lupus cohort. Organ-specific disease manifestations, the modified SLE disease activity index (M-SLEDAI) score, disease flares (M-SLEDAI increase > or =3) and predictive value of anti-dsDNA Ab testing [by enzyme-linked immunoabsorbent assay (ELISA) and Crithidia luciliae immunofluorescence (CLIFT) assays] were related to past anti-dsDNA Ab status.

RESULTS

Anti-dsDNA Ab was previously demonstrated in 54 (57%) patients (group 1), while they were not earlier detected in 40 (43%) patients (group 2). The number of patients experiencing flares (46 vs 25%, p<0.01), the total number of flares (75 vs 17, p<0,001) as well as overall (60 vs 24 per 100 patient years, p<0,001) and organ-specific flare rate were higher in group 1. After adjustment for control frequency, group 1 remained at a higher risk for renal flares [odds ratio (OR) 2.4; confidence interval (CI) 1.5-4.1], and group 2 was at a higher risk for skin flares (OR 0.7; CI 0.5-0.8). While anti-dsDNA Ab testing overall was performed slightly more often in group 1 (OR 1.45; CI 1.0-4.6), anti-dsDNA Ab testing during flares was similar in both groups.

CONCLUSION

The past presence of anti-dsDNA Ab identified patients with an increased risk of subsequent renal flares. However, as a new onset of anti-dsDNA Abs occurred late in the disease course, prior anti-dsDNA status was not adequate to predict disease flares.

Home-exercise regimes for the management of non-specific temporomandibular disorders

There is a consensus on treatment strategies for temporomandibular disorders (TMDs) being reversible. Among reversible therapies, physiotherapy is often chosen for the treatment of TMD pain and dysfunction because it is simple and non-invasive, it has a low cost as compared with other treatments, it allows an easy self-management approach, it allows a good doctor-patient communication, and it can be managed by the general practitioner. Home-exercises regime protocols are reviewed in this article in the context of the biopsychosocial approach. The actual evidence for the efficacy of home physical exercises is weak because of the very limited number of randomized clinical trials (RCTs) available in literature. Therefore, there is a need for further well-designed studies and RCTs to investigate the therapeutic efficacy. Recent reports and clinical experience, however, suggest that this approach can be promising, particularly if it is tailored towards the individual patient. The favourable cost benefit ratio over other treatment modalities seems to indicate that physiotherapy can be regarded as a first choice approach in selected TMD patients.

Is closer linkage between systemic lupus erythematosus and anti-double-stranded DNA antibodies a desirable and attainable goal?

The anti-double-stranded DNA (anti-dsDNA) antibody test incorporated in the 1982 revised American College of Rheumatology criteria for the classification of systemic lupus erythematosus needs updating to reflect current insights and technical achievements, including allowance for the presence of nonpathogenic anti-dsDNA antibodies. As we need to develop at least some measure of pathogenicity of anti-dsDNA antibodies, we propose that initial anti-dsDNA antibody screening is done by sensitive ELISA and supplemented by more stringent assays. Simultaneously the relevance of anti-dsDNA antibody presence needs to be restricted to clinical manifestations, thought to be caused by anti-dsDNA antibody and within an appropriate time frame.

Specificity and immunochemical properties of anti-DNA antibodies induced in normal mice by immunization with mammalian DNA with a CpG oligonucleotide as adjuvant

To elucidate the role of DNA antigen drive in the anti-DNA response, the specificity and immunochemical properties of anti-DNA antibodies induced in normal mice by immunization with double stranded (ds) mammalian DNA with a CpG oligonucleotide (ODN) adjuvant were characterized. Like spontaneous anti-DNA from MRL/lpr mice, the induced anti-DNA bound cross-reactively to DNA from five different species by ELISA. The induced antibodies displayed a predominance of IgG2a and had much lower amount of IgG3 than spontaneous antibodies. Surface plasmon resonance indicated that the induced and spontaneous anti-DNA antibodies have a similar range of avidity and binding kinetics. While sera from the MRL/lpr mice had substantial binding to histones and nucleosomes, the immunized mice had antibody levels to these antigens similar to those of mice treated only with incomplete Freund's adjuvant. Together, these results indicate that normal mice can produce autoantibodies to dsDNA, with a CpG ODN allowing the generation of antibodies resembling those in spontaneous autoimmunity.

Induction of anti-DNA antibodies in preautoimmune NZBxNZW F1 mice by immunization with a DNA-DNase I complex

Recent studies suggest that anti-DNA antibodies may arise from the immune response to a complex of DNA and a DNA-binding protein. One of the protein targets frequently recognized by anti-DNA antibodies is the enzyme DNase I. To investigate the possible role of DNase I in the induction of anti-DNA antibodies, we immunized preautoimmune NZBxNZW F1 mice with a complex of DNA and DNase I emulsified in complete Freund's adjuvant. Control mice received DNA or DNase in adjuvant. IgG anti-dsDNA antibodies were induced in 50% of the mice immunized with DNA-DNase, in 25% of the mice immunized with DNase and in 6% of the mice immunized with DNA. However, immunized mice that produced anti-DNA antibodies did not develop renal disease. These data show that a DNA-binding protein like DNase may act as carrier in the immune response that leads to anti-DNA antibodies production in an autoimmune strain, but the induced anti-dsDNA antibodies have a low pathogenic potential.

T cell lines specific for polyomavirus T-antigen recognize T-antigen complexed with nucleosomes: a molecular basis for anti-DNA antibody production

We have previously demonstrated that in vivo expression of the polyomavirus DNA-binding T-antigen initiated production of IgG antibodies to T-antigen and to DNA, but not to a panel of autoantigens not related to nucleosomes, indicating an antigen-selective T cell-dependent B cell response. In this study, we demonstrate that CD4-positive T cells from both normal and systemic lupus erythematosus (SLE) patients readily proliferate in response to pure T-antigen, and also to T-antigen in complex with nucleosomes. T-antigen-specific T cell lines from both normal individuals and SLE patients proliferate in response to nucleosome-T-antigen complexes, but not to nucleosomes or histones. B cells co-cultured with T-antigen-specific T cells and stimulated with nucleosome-T-antigen complexes produce anti-T-antigen and anti-DNA antibodies, indicating that such CD4-positive T cells have the potential to interact with B cells specific for individual components of nucleosome-T-antigen complexes. Thus, a non-self DNA-binding protein like polyomavirus T-antigen may initiate and maintain an antibody response to DNA when T-antigen is actively expressed.

Screening tests for antinuclear antibodies (ANA): selective use of central nuclear antigens as a rational basis for screening by ELISA

Rational, fully automated ELISA screening tests for ANA have become accessible for routine use. Full length, recombinant or purified naturally expressed antigens can be selected to deliver well defined screening tests, designed to detect ANAs of established clinical significance, while unknown specificities with no clear biological impact are omitted. By comparing results of ANA screening by immunofluorescence (IIF) on tissue section with HEp-2 cells, a correlation of 88% was revealed, while 86% of HEp-2-positive sera bound tissue sections. Eighty-nine percent of HEp-2 ANA-positive sera bound in ANA ELISA I. Seventy-five percent of ANAs detected in ELISA I also bound in ELISA II. These correlations were statistically significant. ANAs detected in ANA ELISA I were all detected upon retesting in both ANA screening ELISA systems, and also by antigen-specific ELISAs. Specific ANAs defined by ELISA, immunodiffusion or Crithidia tests were detected in both ANA ELISA tests. These data demonstrate that most ANAs detected by immunofluorescence tests contain a dominating repertoire of specificities covered by the ANA ELISA systems. The sensitivity of the different ELISA tests can easily be adjusted to internationally defined consensus levels, and screening for ANA using both ELISA systems detects expected ANA specificities in ongoing international quality assessment programs.