Anti-double-stranded DNA antibodies in the healthy elderly: prevalence and characteristics

Cytoplasmic DNA: sources, sensing, and role in aging and disease

Endogenous cytoplasmic DNA (cytoDNA) species are emerging as key mediators of inflammation in diverse physiological and pathological contexts. Although the role of endogenous cytoDNA in innate immune activation is well established, the cytoDNA species themselves are often poorly characterized and difficult to distinguish, and their mechanisms of formation, scope of function and contribution to disease are incompletely understood. Here, we summarize current knowledge in this rapidly progressing field with emphases on similarities and differences between distinct cytoDNAs, their underlying molecular mechanisms of formation and function, interactions between cytoDNA pathways, and therapeutic opportunities in the treatment of age-associated diseases.

Phenotypic and Functional Characterization of Double Negative B Cells in the Blood of Individuals With Obesity

We have previously shown that obesity is associated with increased secretion of IgG antibodies with anti-self-reactivity. In this paper, we confirm and extend our previous findings. We show that the plasma of individuals with obesity is enriched in autoimmune antibodies whose levels are positively associated with blood frequencies of the subset of Double Negative (DN) B cells, which is the most pro-inflammatory B cell subset. We also show that DN B cells, significantly increased in the blood of obese versus lean individuals, are characterized by higher expression of immune activation markers and of the transcription factor T-bet, both associated with autoimmunity. The removal of DN B cells from the peripheral B cell pool significantly decreases in vitro secretion of anti-self IgG antibodies. These results altogether confirm the crucial role of DN B cells in the secretion of anti-self IgG antibodies in individuals with obesity.

Serum antinuclear antibodies associate with worse prognosis in AQP4-positive neuromyelitis optica spectrum disorder

BACKGROUND

Studies have demonstrated that antinuclear antibodies (ANAs) may be correlated with neuromyelitis optica spectrum disorder (NMOSD). However, the conflicting results of studies about the value of ANAs in AQP4 antibody-positive NMOSD patients need to be further investigated.

MATERIAL

Case data were collected from 143 patients with AQP4 antibody-positive NMOSD. Patients were divided into two groups based on the ANA test results. The analysis of clinical characteristics, laboratory tests, and MRI examination results were compared between two groups: the NMOSD patients with ANA (+) and with ANA (-).

RESULTS

Disease duration of NMOSD is shorter in the ANA (+) patients with EDSS < 4 than in the ANA (-) patients (12.05 ± 16.73 versus 29.43 ± 41.03, p-value = .013). The median time from disease onset to an EDSS score of 4.0 is significantly longer in the ANA (-) NMOSD patients than in the ANA (+) patients (48.2 months versus 24 months, p = .04). In addition, ANA (RR, 2.234; 95% CI, 1.078-4.629; p-value = .031) can predict the severity of NMOSD.

CONCLUSIONS

Antinuclear antibodies seem to be associated with more severe disease activity in NMOSD patients.

Self-DNA at the Epicenter of SLE: Immunogenic Forms, Regulation, and Effects

Self-reactive B cells generated through V(D)J recombination in the bone marrow or through accrual of random mutations in secondary lymphoid tissues are mostly purged or edited to prevent autoimmunity. Yet, 10–20% of all mature naïve B cells in healthy individuals have self-reactive B cell receptors (BCRs). In patients with serologically active systemic lupus erythematosus (SLE) the percentage increases up to 50%, with significant self-DNA reactivity that correlates with disease severity. Endogenous or self-DNA has emerged as a potent antigen in several autoimmune disorders, particularly in SLE. However, the mechanism(s) regulating or preventing anti-DNA antibody production remain elusive. It is likely that in healthy subjects, DNA-reactive B cells avoid activation due to the unavailability of endogenous DNA, which is efficiently degraded through efferocytosis and various DNA-processing proteins. Genetic defects, physiological, and/or pathological conditions can override these protective checkpoints, leading to autoimmunity. Plausibly, increased availability of immunogenic self-DNA may be the key initiating event in the loss of tolerance of otherwise quiescent DNA-reactive B cells. Indeed, mutations impairing apoptotic cell clearance pathways and nucleic acid metabolism-associated genes like DNases, RNases, and their sensors are known to cause autoimmune disorders including SLE. Here we review the literature supporting the idea that increased availability of DNA as an immunogen or adjuvant, or both, may cause the production of pathogenic anti-DNA antibodies and subsequent manifestations of clinical disease such as SLE. We discuss the main cellular players involved in anti-DNA responses; the physical forms and sources of immunogenic DNA in autoimmunity; the DNA-protein complexes that render DNA immunogenic; the regulation of DNA availability by intracellular and extracellular DNases and the autoimmune pathologies associated with their dysfunction; the cytosolic and endosomal sensors of immunogenic DNA; and the cytokines such as interferons that drive auto-inflammatory and autoimmune pathways leading to clinical disease. We propose that prevention of DNA availability by aiding extracellular DNase activity could be a viable therapeutic modality in controlling SLE.

Anticyclic Citrullinated Peptide Antibodies 3.1 and Anti-CCP-IgA Are Associated with Increasing Age in Individuals Without Rheumatoid Arthritis

OBJECTIVE

We investigated the association of age and anticyclic citrullinated peptide antibodies (anti-CCP) in subjects without rheumatoid arthritis (RA).

METHODS

Serum was tested for anti-CCP3.1 (IgG/IgA) in 678 first-degree relatives (FDR) of patients with RA and 330 patients with osteoarthritis (OA). Individual isotypes (anti-CCP-IgA and anti-CCP-IgG) were also tested in all FDR.

RESULTS

In FDR, increasing age was significantly associated with positivity for anti-CCP3.1 (per year, OR 1.03) and anti-CCP-IgA (per year, OR 1.05) but not anti-CCP-IgG. In FDR and OA subjects, anti-CCP3.1 prevalence was significantly increased after age 50 years.

CONCLUSION

Increasing age in individuals without RA should be considered in the interpretation of anti-CCP3.1 positivity.

Autoantibody Profiling in Lupus Patients using Synthetic Nucleic Acids

Autoantibodies to nuclear components of cells (antinuclear antibodies, ANA), including DNA (a-DNA), are widely used in the diagnosis and subtyping of certain autoimmune diseases, including systemic lupus erythematosus (SLE). Despite clinical use over decades, precise, reproducible measurement of a-DNA titers remains difficult, likely due to the substantial sequence and length heterogeneity of DNA purified from natural sources. We designed and tested a panel of synthetic nucleic acid molecules composed of native deoxyribonucleotide units to measure a-DNA. ELISA assays using these antigens show specificity and reproducibility. Applying the ELISA tests to serological studies of pediatric and adult SLE, we identified novel clinical correlations. We also observed preferential recognition of a specific synthetic antigen by antibodies in SLE sera. We determined the probable basis for this finding using computational analyses, providing valuable structural information for future development of DNA antigens. Synthetic nucleic acid molecules offer the opportunity to standardize assays and to dissect antibody-antigen interactions.

Systemic lupus erythematosus biomarkers: the challenging quest

SLE, a multisystem heterogeneous disease, is characterized by production of antibodies to cellular components, with activation of both the innate and the adaptive immune system. Decades of investigation of blood biomarkers has resulted in incremental improvements in the understanding of SLE. Owing to the heterogeneity of immune dysregulation, no single biomarker has emerged as a surrogate for disease activity or prediction of disease. Beyond identification of surrogate biomarkers, a multitude of clinical trials have sought to inhibit elevated SLE biomarkers for therapeutic benefit. Armed with new -omics technologies, the necessary yet daunting quest to identify better surrogate biomarkers and successful therapeutics for SLE continues with tenacity.

Ultrasensitive Antibody Detection by Agglutination-PCR (ADAP)

Antibodies are widely used biomarkers for the diagnosis of many diseases. Assays based on solid-phase immobilization of antigens comprise the majority of clinical platforms for antibody detection, but can be undermined by antigen denaturation and epitope masking. These technological hurdles are especially troublesome in detecting antibodies that bind nonlinear or conformational epitopes, such as anti-insulin antibodies in type 1 diabetes patients and anti-thyroglobulin antibodies associated with thyroid cancers. Radioimmunoassay remains the gold standard for these challenging antibody biomarkers, but the limited multiplexability and reliance on hazardous radioactive reagents have prevented their use outside specialized testing facilities. Here we present an ultrasensitive solution-phase method for detecting antibodies, termed antibody detection by agglutination-PCR (ADAP). Antibodies bind to and agglutinate synthetic antigen-DNA conjugates, enabling ligation of the DNA strands and subsequent quantification by qPCR. ADAP detects zepto- to attomoles of antibodies in 2 μL of sample with a dynamic range spanning 5-6 orders of magnitude. Using ADAP, we detected anti-thyroglobulin autoantibodies from human patient plasma with a 1000-fold increased sensitivity over an FDA-approved radioimmunoassay. Finally, we demonstrate the multiplexability of ADAP by simultaneously detecting multiple antibodies in one experiment. ADAP's combination of simplicity, sensitivity, broad dynamic range, multiplexability, and use of standard PCR protocols creates new opportunities for the discovery and detection of antibody biomarkers.

The janus head of T cell aging - autoimmunity and immunodeficiency

Immune aging is best known for its immune defects that increase susceptibility to infections and reduce adaptive immune responses to vaccination. In parallel, the aged immune system is prone to autoimmune responses and many autoimmune diseases increase in incidence with age or are even preferentially encountered in the elderly. Why an immune system that suboptimally responds to exogenous antigen fails to maintain tolerance to self-antigens appears to be perplexing. In this review, we will discuss age-associated deviations in the immune repertoire and the regulation of signaling pathways that may shed light on this conundrum.

Acute renal failure secondary to tuberculosis: a diagnostic challenge

Tuberculosis is a multiorgan disease with varied clinical presentations and is reemerging due to increasing immigration and globalization. We present the case of an immigrant female patient who developed acute renal failure with clinical and biochemical features suggestive of lupus nephritis but with a timely renal biopsy showing caseating granulomata in the renal parenchyma consistent with renal tuberculosis. Despite treatment with antituberculosis treatment and resolution of TB on repeat renal biopsy, she remained haemodialysis dependent. We discuss the diagnostic challenges faced in this presentation and also explore possible differential diagnoses. This rare presentation highlights the importance of renal biopsy in the diagnosis and treatment of acute renal failure and the atypical presentation of tuberculosis.

Prevalence of disease-specific antinuclear antibodies in general population: estimates from annual physical examinations of residents of a small town over a 5-year period

The aim of this study was to investigate the types and prevalence of disease-specific antinuclear antibodies (ANAs) and their relationship to rheumatic diseases in the general Japanese population. An immunofluorescence (IF) method was used for the first screening of ANA levels in serum samples obtained from 2181 residents of a small Japanese town. Individuals positive for IF-ANA were then further tested for disease-specific ANAs using eight enzyme immunoassays. Physical status and the presence of illness were determined by means of questionnaires and medical examinations. Based on the result of the IF-ANA assay, the rates of positive samples at 1:40 and 1:160 dilutions were 26.0 and 9.5%, respectively, with females have significantly higher positivity rates than males (P < 0.0001). Among 566 IF-ANA-positive individuals, 100 individuals were found to have 114 disease-specific ANAs. Anti-SSA/Ro, anti-centromere, and anti-U1RNP antibodies were detected in 58, 30, and 11 individuals, respectively, but anti-Sm, anti-Scl-70, and anti-Jo-1 antibodies were undetectable. Questionnaires and medical examinations revealed that among 60 disease-specific ANA-positive individuals that were available for testing, six had Sjögren's syndrome (SS), five were suspected of having SS, and five had rheumatoid arthritis. Surprisingly, 34 (57%) of the disease-specific ANA-positive individuals were clinically healthy. Anti-SSA/Ro, anti-centromere, and anti-U1RNP antibodies were quite frequent among clinically healthy Japanese subjects, although anti-Sm, anti-Scl-70, and anti-Jo-1 antibodies were not. Of the 60 individuals who tested positive for disease-specific ANAs, 30% (18/60) actually manifested systemic rheumatic diseases, while 50% showed no detectable signs or symptoms of rheumatic diseases.

Elderly-Onset Systemic Lupus Erythematosus

Systemic lupus erythematosus is an autoimmune multi-system disease of uncertain aetiology with highly variable clinical manifestations. Women of child-bearing age are most often affected; however, approximately 10-20% of cases occur in older patients. Elderly-onset lupus has been defined in various studies as onset of lupus after age 50-65 years. Menopause and changes in cellular immunity with aging may contribute to development of lupus in older adults. Many studies suggest that the clinical and serological features of elderly-onset lupus differ from those of lupus in younger patients. Arthritis, fever, serositis, sicca symptoms, Raynaud's syndrome, lung disease and neuropsychiatric symptoms are more common in patients with elderly-onset lupus, while malar rash, discoid lupus and glomerulonephritis are less common in elderly-onset patients compared with younger lupus patients. Most elderly-onset lupus patients have a positive anti-nuclear antibody test, but the prevalence of anti-double-stranded DNA and hypocomplementaemia is lower in elderly-onset patients than in younger patients. Rheumatoid factor, anti-Ro/Sjögren's syndrome (SS) A and anti-La/SSB are more often positive in elderly-onset patients. The diagnosis of elderly-onset lupus may be delayed for many months: insidious onset, low prevalence and similarity to other more common disorders make the diagnosis of lupus challenging in this population. Treatment of lupus in the elderly may be complicated by co-morbidities and increased risk of toxicities from usual treatments. Optimal management of elderly-onset lupus is empiric because of a lack of randomised controlled studies. However, the approach to treatment is similar regardless of the age of the patient. This article discusses the prevalence, clinical course, serological features, prognosis and treatment of elderly-onset systemic lupus erythematosus.

Late onset systemic lupus erythematosus: no substantial differences using different cut-off ages

To compare the clinical, laboratory and immunological features of a group of Caucasian systemic lupus erythematosus (SLE) patients in relation to age at disease onset. Three groups of patients with different ages at disease onset were analysed and compared: group A (30 patients, >or=65 years); group B (62 patients, 50-64 years) and group C (163 patients, <50 years). All patients were regularly followed-up for a mean period of 6.5 years. Female predominance was reduced in groups A and B. Time-lapse between disease onset and diagnosis was longer in group A and B. There were no statistically significant differences in clinical features. The only relevant difference was observed in peripheral nervous system (PNS) involvement, more frequent in group A. Anti-dsDNA and RF were more frequent in group A. Complement levels were reduced more frequently in group C. No differences were observed in disease activity scores, while SLICC/ACR score was higher in group A. In Caucasian SLE patients, age at disease onset is not associated with differences in clinical features apart from a more frequent PNS involvement in elderly patients. In the same group, the organ damage seems to develop more rapidly mostly due to higher susceptibility to jatrogenic side effects.

Autoantibody Determination in the Diagnosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that usually develops in young women aged 18-50 years and is characterized by the presence of autoantibodies. Diagnosis is difficult as SLE is a great imitator of other diseases. When SLE is suspected clinically in a patient (involvement of two or more organ systems), an initial laboratory evaluation would be antinuclear antibody (ANA) testing. If ANA is negative, SLE is unlikely and results positive at less than 1:40 strongly argue against SLE. Other explanations for organ system involvement should be pursued. Results positive at greater than 1:40 may merit further evaluation for SLE and at times referral to a rheumatologist for a full SLE evaluation. While the American College of Rheumatology classification criteria for SLE are primarily a tool for research, they may be useful clinically, in that those patients fulfilling four or more criteria are highly likely to have SLE.

[Systemic lupus erythematosus with disease onset after age 65]

OBJECTIVES

Systemic lupus erythematosus with disease-onset in the elderly has rarely been studied (only one report about 21 patients with disease onset at 65 and older). Is the management of this pathology modified in this population?

METHODS

Seventeen hospitalised cases of lupus patients with disease onset at 65 or older are retrospectively reported between 1988 and 2000. The results are compared with those of younger subjects.

RESULTS

The female to male ratio is 1.83. Mean age at disease onset is 71.9 +/- 3.5 years. Mean duration of follow-up is 3.5 +/- 2.4 years. Main initial symptoms are: deterioration of general status (41%), arthritis (35%), cutaneous manifestations (35%), thrombo-embolism (24%) and pleuritis (18%). Malar rash is uncommon (12%). Nephropathy is never a revealing symptom and is rarely serious during the disease's evolution. Like in neurologic manifestations, the etiology has to be discussed in relation to associated co-morbidities. Concerning haematologic features, lymphopenia is found in 82% of the cases with a questionable specificity. Antinuclear antibodies are constant, anti-dsDNA antibodies are found in 82% of the cases, antibodies to extractable nuclear antigens in 50%, and anticoagulant circulating activity in 59%. Prognosis is difficult to assess in such a limited series but 5-years survival probability is 83%. Glucocorticoid lead to 50% of major complications.

CONCLUSIONS

This study focuses on the particular initial manifestations of systemic lupus erythematosus in the elderly (deterioration of general status, thrombosis, unusual cutaneous symptoms), and on the specificity of differential diagnosis and treatment.

Systemic lupus erythematosus in the elderly

Aging modifies the clinical presentation and course of autoimmune disorders, although the mechanisms by which this occurs remain to be determined. Current evidence cited above supports the general concept that there is a natural senescence of the immune system. This evidence would suggest that somehow senescence directly affects gene expression, resulting in biochemical abnormalities that culminate in T-cell immunodysfunctions. This may be a principal factor that attenuates the autoimmune response to self-antigen and, therefore, the disease course. The authors speculate that there is a disorder primary to the T cell in SLE that is expressed as abnormal immunologic responses to self-antigens, resulting in autoimmunity. Although understanding of this primary T cell disorder is still limited, clinicians now know that the T cell harbors abnormal signaling pathways that reflect defective biochemical functions and seem to be genetically regulated. This aberrant signaling would be anticipated to affect both principal T cell subsets. It may hinder the capacity of cells, such as CD8 T cells, to effectively down-regulate the response of autoreactive CD4 helper T cells to autoantigens. Loss of self-regulation would manifest itself as loss of tolerance, a fundamental component of autoimmunity. The future challenge is to understand how aberrant signaling leads to loss of tolerance. Given this underlying genetic susceptibility in an aged individual whose T cells also are undergoing natural senescence, the authors suggest that it is conceivable that a stress factor may tip the balance in the favor of clinical disease. One such factor may be unspecified environmental stimuli. Yet another consideration is an intercurrent illness, such as an infection. It remains to be determined, however, what these environmental stimuli are and how they impact on the immune system to trigger disease.

The use of laboratory tests in the diagnosis of SLE

ANA IIF is an effective screening assay in patients with clinical features of SLE and will detect most anti-ssDNA, anti-dsDNA, ENAs, and other autoantibodies. False positives are common. The clinical importance cannot be extrapolated from the ANA titre or pattern, although higher titres (> 1/160) are more likely to be important. HEp-2 cells are the most sensitive substrate for ANA detection, but this must be balanced against an increased incidence of insignificant positivity. ANA positive samples should be subjected to more specific assays for the diagnosis of SLE. A combination of ENA (Ro/La/Sm/RNP) and dsDNA assays will detect most patients with SLE as long as the characteristics of the assays used are well understood. ESR and CRP measurements provide useful additional information. Sjogren's syndrome and MCTD will produce overlapping serology with SLE, and anti-dsDNA titres are sometimes seen in autoimmune hepatitis and rheumatoid arthritis. All results should be reported in the light of the clinical details, by an experienced immunologist. A suggested diagnostic protocol is outlined in fig 1. The type of assay used crucially influences the predictive value of the tests. ELISA technology dominates routine laboratory practice, but tends to produce more false positive and true weak positive results, which may reduce the PPV of the test. This can be minimised by using IgG specific conjugates and careful assay validation. The NPV for SLE [figure: see text] is high for most assays but the PPV varies. Where necessary, laboratories should use crithidia or Farr dsDNA assays to confirm dubious ELISA dsDNA results, and ID/IB to confirm dubious ENA results. For monitoring, a precise, quantitative assay is required. It is unclear whether the detection of IgM or low affinity antibodies has a role here. A combination of anti-dsDNA, C3, C4, CRP, and ESR assays provides the most useful clinical information. Anti-ssDNA assays are likely to be useful, and are potentially more robust than anti-dsDNA assays, but require more validation. Local validation of individual assays and EQA participation is essential. Not all assays that apparently measure the same antibody specificities have equal clinical relevance, even within a single technology. Insufficient international or national reference preparations are currently available for many antibody specificities to enable effective standardisation. Quality assurance schemes reveal large differences in units reported by different assays for some analytes, even when calibrated against an IRP or equivalent reference preparation. Serial results can therefore only be compared from the same laboratory at present. Most autoantibodies increase during active disease, but few prospective data are currently available to justify treatment on the basis of rising titres. Further randomised prospective studies are required to examine the importance of antibody isotype and affinity in the monitoring of SLE by individual assay methods. The most important aspect of the appropriate use of laboratory assays is to become familiar with the limitations of the technology currently in use in your local laboratory, and to consult with your clinical immunologist in cases of doubt, preferably before commencing serological screening.

Stability of natural self-reactive antibody repertoires during aging

We have used a quantitative immunoblotting technique to analyze the repertoires of self-reactive antibodies in serum samples obtained from the same five healthy adults over a 25-year interval. The average age of the donors was 43 years at the time of the first serum sample and 69 years at the time of the second serum sample. The antibody repertoires of IgM and IgG were found to be strikingly similar among individuals in both early and late samples. Densitometric profiles of self-reactivity of serum IgM and of purified serum IgG remained unchanged over the 25-year interval. The total reactivity of serum IgG decreased significantly over the 25-year period. The observed stability of the natural self-reactive IgM and IgG antibody repertoires with aging supports the view that autoreactive B cells in the normal immune system are positively selected for reactivity with a limited set of immunodominant self-antigens throughout life.

Analysis of the natural human IgG antibody repertoire: life-long stability of reactivities towards self antigens contrasts with age-dependent diversification of reactivities against bacterial antigens

We used a quantitative immunoblotting technique to analyze the repertoires of IgG antibody reactivities in the serum of healthy young children, young adult males and aged males with self and non-self antigens. Densitometric patterns of reactivity of purified IgG with self antigens were highly conserved between individuals within a given age group and across age groups. Inter-individual differences were observed, however, upon analysis of self reactivities of IgG in whole serum. A striking heterogeneity between individuals within a given age group and across age groups characterized the reactivity of purified IgG and of IgG in whole serum with bacterial antigens. Inter-individual differences were more marked among aged individuals than among individuals of other age groups. Analysis of variances of reactivities of IgG with bacterial antigens further demonstrated an increased diversity of repertoires of aged donors compared with those of young adults and children. Our results document the stability of the self-reactive repertoires of IgG throughout life, which contrasts with the diversification of the repertoire of IgG antibody reactivities directed toward foreign antigens with aging. These findings support the concept that self-reactive antibody repertoires are positively selected throughout life by a restricted set of self antigens shared by all individuals.

Study of procainamide hapten-specific antibodies in rabbits and humans

Procainamide (PA) is the drug most commonly associated with the induction of autoantibodies and drug-related lupus (DRL). While the majority of these patients express autoantibodies, antibodies to the parent drug and metabolites, PA-hydroxylamine (PAHA) or nitroso-PA (NOPA), have not been reported in humans. Hapten-carrier conjugates were prepared using human hemoglobin (HgB) or autologous rabbit erythrocytes with PAHA or NOPA. PA was conjugated to rabbit serum albumin (RSA) or egg albumin (OVA) via diazotization and condensation methods. Rabbits were immunized with hapten conjugates in Freund's adjuvant. These hapten-carrier compounds (5-10 micrograms/ml) were used as test antigens for antibodies in sera from the rabbits and 40 patients on chronic PA treatment. 10 SLE patients, 33 elderly and 20 young normal controls by ELISA. Type I and II collagens were also used as test antigens for human sera. Sera from rabbits immunized with the PA compounds had elevated IgG antibody values to PA, PAHA and NOPA, but no autoantibodies. Absorption of the rabbit sera with the PA compounds reduced the antibody levels; ssDNA and histones failed to inhibit the total binding values. Mean binding to PA-OVA was 0.95 +/- 0.41 for PA patients and 1.37 +/- 0.26 standard error of means (S.E.M.) in the SLE patients compared to 0.37 +/- 0.14 S.E.M. in the normal sera (P < or = 0.05); similar binding values to PAHA-HgB and NOPA-HgB were also observed. Sixty-eight percent of the PA patients had antibodies to type II collagen. Elevated binding values to PA compounds were inhibited by absorption of human sera with ssDNA or total histones; absorption with PA or PAHA had no significant effect. These findings suggest that sera from PA patients containing high titers of autoantibodies cross-react in vitro with unrelated antigens.