Autoantibody explosion in systemic lupus erythematosus: more than 100 different antibodies found in SLE patients

APS--more systemic disease than SLE

The antiphospholipid syndrome is a systemic autoimmune disease that can have serious consequences for patients. Importantly, there is a wide range of clinical presentations. In this issue we have attempted to provide an overview of these features and place it in the context of autoimmunity.

Drug insight: autoimmune effects of medications-what's new?

Autoantibodies and lupus-like syndromes can develop following the use of certain medications; however, although many patients develop autoantibodies, only a minority develop clinical features. Although these autoantibodies primarily consist of antinuclear and antihistone antibodies, additional types of antibody, such as antineutrophil cytoplasmic antibodies and anti-double-stranded DNA antibodies, have been reported in association with minocycline and tumor necrosis factor inhibitor therapy. Clinical features of drug-related lupus usually consist of constitutional symptoms, arthralgias, arthritis, myalgias and serositis, although cutaneous manifestations have been reported in association with the use of tumor necrosis factor inhibitors. Typically, clinical features resolve with discontinuation of the medication, although antibodies can persist for months or years. Arthralgias and inflammatory arthritis have also been reported in association with the use of aromatase inhibitors and other biologic agents such as interleukins and interferons.

A peptide that ameliorates lupus up-regulates the diminished expression of early growth response factors 2 and 3

Expansion of autoreactive T cells and their resistance to anergy was demonstrated in systemic lupus erythematosus (SLE). A pair of transcription factors, early growth response 2 (Egr-2) and 3 (Egr-3), are negative regulators of T cell activation that were shown to be important in anergy. A peptide (designated hCDR1 for human CDR1) based on the CDR-1 of an anti-DNA Ab ameliorated SLE in both induced and spontaneous lupus models. Our objectives were to determine the expression levels of Egr-2 and Egr-3 in autoreactive T cells following immunization with the lupus-inducing anti-DNA Ab that bears a common Id designated 16/6Id and also in a full-blown SLE and to determine the effect of hCDR1 on these transcription factors. We demonstrated diminished expression levels of Egr-2 and Egr-3 mRNA both early after immunization with the 16/6Id and in SLE-afflicted (NZB x NZW)F1 (New Zealand Black and New Zealand White) mice. Furthermore, by down-regulating Akt phosphorylation and up-regulating TGFbeta secretion, treatment with hCDR1 significantly up-regulated Egr-2 and Egr-3 expression. This was associated with an increased expression of the E3 ligase Cbl-b. Inhibition of Akt in T cells of immunized mice decreased, whereas silencing of the Egr-2 and Egr-3 in T cells of hCDR1-treated mice increased IFN-gamma secretion. Thus, hCDR1 down-regulates Akt phosphorylation, which leads to up-regulated expression of T cell Egr-2 and Egr-3, resulting in the inhibition of IFN-gamma secretion that is required for the maintenance of SLE.

Anti-annexin II antibodies in systemic autoimmune diseases and antiphospholipid syndrome

OBJECTIVES

The objective of this study were (1) to evaluate the prevalence of anti-annexin II antibodies in patients with various autoimmune diseases and antiphospholipid syndrome and (2) to correlate anti-annexin II antibodies with anti-phospholipid antibodies.

MATERIALS AND METHODS

Anti-annexin II antibodies and anti-phospholipid were detected, using an enzyme-linked immunosorbent assay, in the serum of patients with primary antiphospholipid syndrome (n = 16), systemic lupus erythematosus (n = 53), primary Sjögren syndrome (n = 71), systemic sclerosis (n = 17), systemic vasculitis (n = 18), and rheumatoid arthritis (n = 119). Healthy blood donors (n = 99) were used as controls.

RESULTS

Anti-annexin II antibodies were significantly more prevalent in patients with connective tissue diseases (8.5%), especially antiphospholipid syndrome (14.8%) and rheumatoid arthritis (10%), than in controls (2%). An inverse correlation was observed between anti-annexin II antibodies and antiphospholipid antibodies.

CONCLUSION

Annexin II can be recognized by antibodies in serum from patients with systemic autoimmune disorders. Further studies are required to determine the clinical significance of anti-annexin II antibodies in rheumatoid arthritis and to determine their diagnostic value in discriminating clinical subgroups of patients with antiphospholipid syndrome.

Viral infection can induce the production of autoantibodies

PURPOSE OF REVIEW

To review the current literature and summarize the main principles found between viral infections and the subsequent production of autoantibodies.

RECENT FINDINGS

We concentrate on recent findings involving three viral agents, one of which is Epstein-Barr virus, which has been associated with many autoimmune diseases and is classically considered to induce systemic lupus erythematosus. As we will discuss, this occurs through molecular mimicry between Epstein-Barr virus nuclear antigen 1 and lupus-specific antigens such as Ro, La or dsDNA, through induction of Toll-like receptor hypersensitivity by Epstein-Barr virus latent membrane protein 2A or by creating immortal B and T cells by loss of apoptosis. Hepatitis B virus was found to share amino acid sequences with different autoantigens. Tissue damage and the release of intracellular components is just another example of the autoantibody production caused by this virus. Cytomegalovirus has often been controversially associated with several autoimmune diseases and, although is the least understood viral infection of the three, appears to be somewhat suspicious.

SUMMARY

Understanding the infectious origin of autoimmune diseases is important as we aim to identify high-risk patients and disrupt this process with vaccines or other medications, ultimately delaying or even preventing the evolution of autoimmune diseases.

Functional variants in the B-cell gene BANK1 are associated with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease characterized by production of autoantibodies and complex genetic inheritance. In a genome-wide scan using 85,042 SNPs, we identified an association between SLE and a nonsynonymous substitution (rs10516487, R61H) in the B-cell scaffold protein with ankyrin repeats gene, BANK1. We replicated the association in four independent case-control sets (combined P = 3.7 x 10(-10); OR = 1.38). We analyzed BANK1 cDNA and found two isoforms, one full-length and the other alternatively spliced and lacking exon 2 (Delta2), encoding a protein without a putative IP3R-binding domain. The transcripts were differentially expressed depending on a branch point-site SNP, rs17266594, in strong linkage disequilibrium (LD) with rs10516487. A third associated variant was found in the ankyrin domain (rs3733197, A383T). Our findings implicate BANK1 as a susceptibility gene for SLE, with variants affecting regulatory sites and key functional domains. The disease-associated variants could contribute to sustained B cell-receptor signaling and B-cell hyperactivity characteristic of this disease.

Insoluble immune complexes are most effective at triggering IL-10 production in human monocytes and synergize with TLR ligands and C5a

PURPOSE

In systemic lupus erythematosus (SLE), a disease of immune complex (IC) deposition, interleukin-10 (IL-10) is thought to promote B-lymphocyte hyperactivity and autoantibody production. Both ICs and Toll-like receptor (TLR) ligands have been shown to stimulate the production of IL-10 by human monocytes. Using an in vitro model, we studied how IC solubility, complement activation products, and TLR ligands could affect IL-10 production by human monocytes stimulated with ICs.

METHODS

Human monocytes were stimulated with soluble or insoluble heat-aggregated human IgG with or without TLR ligands or C5a. Cytokine levels in cell culture supernatants were measured by ELISA. To study cytokine signaling, cell lysates were analyzed by Western blot for total or tyrosine-phosphorylated STAT3.

RESULTS

Insoluble ICs were most effective at stimulating production of IL-10, and costimulation LPS enhanced synthesis of IL-10. In addition, stimulation with insoluble ICs together with C5a enhanced the production of IL-10 by 2-4 fold in either the presence or absence of TLR ligands. Increased STAT3 phosphorylation correlated temporally with enhanced IL-10 production and was reduced by an IL-10 receptor blocking antibody, suggesting that IL-10 was responsible for observed STAT3 phosphorylation.

CONCLUSIONS

Because the immune deposits of SLE are, by definition, insoluble; and because IL-10 is thought to be important for B-cell hyperactivity and autoantibody production, these observations provide a critical link, bridging current views of B-cell hyperactivity with the early concept that SLE may arise from defective clearance of immune complexes.

Autoantibody explosion in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis and pregnancy loss in the presence of antiphospholipid antibodies (aPL), mainly anticardiolipin, anti-beta2-glycoprotein I and lupus anticoagulant. However, similar to systemic lupus erythematosus, APS is also characterized by multiple other autoantibodies including 'non-classical' aPL, as well as other antibodies. Herein we describe the autoantigen properties, prevalence and clinical importance of 30 different antibodies in APS. Among the other antibodies characterizing APS are autoantibodies directed to platelets, glycoproteins, various coagulation factors, lamins, mitochondrial antigens and cell surface markers. Few of these autoantibodies are correlated with the presence of other antibodies, and some may have an additive role in the pro-thrombotic tendency of the syndrome. This autoantibody explosion might be important in early identification of the syndrome and its manifestations.

Antiribosomal-P autoantibodies from psychiatric lupus target a novel neuronal surface protein causing calcium influx and apoptosis

The interesting observation was made 20 years ago that psychotic manifestations in patients with systemic lupus erythematosus are associated with the production of antiribosomal-P protein (anti-P) autoantibodies. Since then, the pathogenic role of anti-P antibodies has attracted considerable attention, giving rise to long-term controversies as evidence has either contradicted or confirmed their clinical association with lupus psychosis. Furthermore, a plausible mechanism supporting an anti-P-mediated neuronal dysfunction is still lacking. We show that anti-P antibodies recognize a new integral membrane protein of the neuronal cell surface. In the brain, this neuronal surface P antigen (NSPA) is preferentially distributed in areas involved in memory, cognition, and emotion. When added to brain cellular cultures, anti-P antibodies caused a rapid and sustained increase in calcium influx in neurons, resulting in apoptotic cell death. In contrast, astrocytes, which do not express NSPA, were not affected. Injection of anti-P antibodies into the brain of living rats also triggered neuronal death by apoptosis. These results demonstrate a neuropathogenic potential of anti-P antibodies and contribute a mechanistic basis for psychiatric lupus. They also provide a molecular target for future exploration of this and other psychiatric diseases.

Significant alterations of biodistribution and immune responses in Balb/c mice administered with adenovirus targeted to CD40(+) cells

CD40 ligation has been shown to promote antigen-presenting functions of dendritic cells, which express CD40 receptor. Here we reported significantly altered biodistribution and immune responses with the use of CD40-targeted adenovirus. Compared with unmodified adenovirus 5, the CD40-targeted adenovirus following intravenous administration (i.v.) resulted in increased transgene expressions in the lung and thymus, which normally do not take up significant amounts of adenovirus. Intradermal injection saw modified adenovirus being mainly processed in local draining lymph nodes and skin. Following intranasal administration (i.n.), neither unmodified nor targeted viruses were found to be in the liver or spleen, which predominantly took up the virus following i.v. administration. However, inadvertent infection of the brain was found with unmodified adenoviruses, with the second highest gene expression among 14 tissues examined. Importantly, such undesirable effects were largely ablated with the use of targeted vector. Moreover, the targeted adenovirus elicited more sustained antigen-specific cellular immune responses (up to 17-fold) at later time points (30 days post boosting), but also significantly hampered humoral responses irrespective of administration routes. Additional data suggest the skewed immune responses induced by the targeted adenoviruses were not due to the identity of the transgene but more likely a combination of overall transgene load and CD40 stimulation.

Quantification of antineural antibodies in autoimmune neurological disorders

More than 50 different neurological pathologies have a confirmed or suspected autoimmune etiology affecting an estimated number of 75 million people worldwide. Autoantibodies are a useful diagnostic marker for most autoimmune diseases even though their pathological role is not evident, and several tests for their detection are commercially available. However, for autoimmune diseases involving the nervous system, lack of clear information on the identity of antineural antibody targets and the presence of many rare diseases have hampered the development of specific diagnostic assays. This review focuses on the actual knowledge on confirmed and suspected autoimmune diseases that target the CNS and the diagnostic relevance of corresponding antineural autoantibodies.

A new target for autoantibodies in patients with rheumatoid arthritis

Early treatment of rheumatoid arthritis (RA) with disease-modifying antirheumatic drugs can achieve a better disease outcome and reduce the severity of joint damage. The presence of autoantibodies in patient sera can precede onset of the disease and thus be predictive of the development of RA. To date, known autoantibodies in RA are positive in only 50-60% of RA patients at onset of disease and even less before the onset of any RA symptom. The aim of this study was to identify new antibodies that could be useful for the diagnosis of RA using synovial membrane proteins, which represent the best source of candidate RA autoantigens. The humoral reactivity of sera from RA patients was explored using immunoblotting on extracted proteins obtained from synovial membranes from RA after synovectomy or arthroplasty. A new target protein with a molecular weight of 26 kDa was found to be recognized by autoantibodies in RA sera. This protein was identified using MALDI-TOF mass spectrometry and two-dimensional electrophoresis as carbonic anhydrase III with a high level of confidence. In conclusion, this study demonstrates new autoantibodies in RA patients that are directed against carbonic anhydrase III. The sensitivity and specificity of these new autoantibodies for RA have to be further evaluated.

Superoxide anion production by neutrophils is associated with prevalent clinical manifestations in systemic lupus erythematosus

To determine the relation between neutrophil function and the clinical characteristics of systemic lupus erythematosus (SLE), the superoxide anion (O2-) production by neutrophils, mediated by FcgammaR and FcgammaR/CR cooperation, was studied in 64 SLE patients classified according to their prevalent clinical manifestations. Three clinically distinct patterns were designated: (1) manifestations associated with the occurrence of cytotoxic antibodies (SLE-I group); (2) manifestations associated with circulating immune complexes (IC; SLE-II group), and (3) manifestations associated with IC and cytotoxic antibodies (SLE-III group). O2- production was evaluated by a lucigenin-dependent chemiluminescent assay in neutrophils stimulated with IC-IgG opsonized or not with complement. No difference in O2- production was observed when neutrophil responses from healthy controls were compared to the unclassified patients. However, when the SLE patient groups were considered, the following differences were observed: (1) SLE-I neutrophils showed lower O2- production mediated by the IgG receptor (FcgammaR) with the cooperation of complement receptors (FcgammaR/CR) than observed in the SLE-II, SLE-III, and healthy groups; (2) neutrophils from the SLE-II group showed a decreased [Formula: see text] production mediated by FcgammaR/CR compared to the SLE-III group, (3) SLE-III neutrophils produced more O(2)(-) than neutrophils from the SLE-II and control groups, and (4) CR showed inefficiency in mediating the O2- production by neutrophils from the SLE-I group. Comparative experiments on the kinetics of chemiluminescence (CL; Tmax and CLmax) disclosed differences only for the SLE-I group. Taken together, these results suggest that differences in oxidative metabolism of neutrophils mediated by FcgammaR/CR may reflect an acquired characteristic of disease associated with distinct clinical manifestations.

Thrombotic thrombocytopenic purpura and Graves disease

Patients with an autoimmune disease have a propensity for development of a second autoimmune disease. We report the first instance of a patient with both idiopathic thrombotic thrombocytopenic purpura (TTP) and Graves disease. The TTP remitted with a combination of plasmapheresis and prednisone. Methimazole led to sustained remission of the hyperthyroid state within 6 weeks. Although hyperthyroidism may induce immune imbalance causing autoimmunity, it is unclear if this influenced the development of TTP in our patient and if treatment of hyperthyroidism alone could have resulted in the cure of both diseases.

OxLDL/beta2GPI-anti-oxLDL/beta2GPI complex and atherosclerosis in SLE patients

It has been demonstrated that atherosclerosis (ATS) is enhanced in autoimmune rheumatic diseases, such as systemic lupus erythematosus (SLE). The reason for this accelerated process is still debatable and, although traditional risk factors are more prevalent in SLE patients than in general population, they do not seem to fully explain the enhanced risk. ATS has the characteristics of an autoimmune chronic disease, involving both the innate and the adaptive immunity. Moreover, it satisfies the four criteria defining an autoimmune disease, proposed by Witebsky and Rose. It has been shown that some autoantibodies, including anti-oxLDL, anti-beta(2)GPI, anti-HSP60/65, and more recently anti-oxLDL/beta(2)GPI, play a key role in the pathogenesis of ATS. However the role of these autoantibodies in accelerated ATS in SLE patients is still controversial. In fact, some of them seem to be proatherogenic and other protective; moreover, it has been demonstrated that induced oral tolerance has a protective role against ATS. We have recently observed that the levels of oxLDL/beta(2)GPI antigenic complexes and their antibodies were higher in patients with SLE than in healthy subjects, but we did not find a clear association between oxLDL/beta(2)GPI complexes and IgG or IgM anti-oxLDL/beta(2)GPI autoantibodies and subclinical ATS in SLE patients. Many other studies are required to explain the role of autoantibodies in the pathogenesis of ATS in SLE patients, because the characteristics of SLE seem to mask their effects for atherogenesis.

Tissue chimerism in systemic lupus erythematosus is related to injury

BACKGROUND

Chimerism indicates the presence of cells from one individual in another individual, and has been associated with several autoimmune diseases. Although this finding may point towards a role for chimerism in the induction of SLE, it could also indicate that chimerism is the result of repair mechanisms after injury.

OBJECTIVE

To perform a post-mortem investigation for the presence of chimerism in 48 organs from seven women with SLE and establish whether there was a relationship between chimerism and injury.

METHODS

Chimeric male cells in female tissue specimens were identified by in situ hybridisation of the Y-chromosome. Organs were categorised into four different groups according to injury experienced.

RESULTS

were compared with those for unaffected control organs. Results: Chimerism was found in all seven patients with SLE. Y-chromosome-positive cells were present in 24 of 48 organs from women with SLE, which was significantly more than in control organs (p<0.001). Chimerism occurred more often in organs from patients with SLE who had experienced injury than in normal control organs, irrespective of whether the injury experienced was SLE-related, non-SLE-related or both.

CONCLUSIONS

This is the first report of the distribution of chimerism in a large number of organs from women with SLE. It shows that the occurrence of chimerism is related to injury. The data support the hypothesis that tissue chimerism is the result of a repair process.

Autoantibodies against Protective Molecules C1q, C-Reactive Protein, Serum Amyloid P, Mannose-Binding Lectin, and Apolipoprotein A1: Prevalence in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of several autoantibodies. Among the multiple factors involved in SLE development, apoptotic defects and impaired clearance of cellular debris have gained considerable interest, as they contribute to autoantigen overload. Several molecules of the innate immunity, also participate in the removal of damaged and apoptotic cells. Among them are C1q, C-reactive protein (CRP), serum amyloid P protein (SAP), mannose-binding lectin (MBL), and apolipoprotein A1 (APO A1). To evaluate the prevalence of autoantibodies against CRP, SAP, MBL, APO A1, and C1q among SLE patients, and their relationship with disease activity, a total of 150 SLE patients were screened for the presence of elevated antibody titers against C1q, CRP, SAP, MBL, and APO A1, utilizing the enzyme-linked immunosorbent assay (ELISA) method. Disease activity was assessed using the ECLAM or SLEDAI scores. The study population comprised two groups of patients: 100 patients with quiescent disease (median ECLAM score 2) comprised the first group, and 50 patients with active disease (median SLEDAI score 16) comprised group 2. Elevated titers of anti-CRP antibodies were significantly elevated only in group 1 (10% versus 4% of controls). Antibodies against SAP were evaluated only among patients in group 1, and were found at a significant high prevalence (20%). Elevated titers of anti-MBL antibodies were significantly elevated only in group 1 (15% versus 3.6%); and antibodies directed against APO A1 were significantly elevated in 21% of group 1, and 50% of group 2 patients. Elevated titers of anti-C1q were evaluated only in group 2, and were found at a significant prevalence of 66%. Significant correlation with disease activity was found only for anti-APO A1 antibodies, and only in group 1. Several patients harbored more than one of the autoantibodies tested. In patients with SLE, autoantibodies directed against protective molecules, that is, acute-phase proteins involved in the disposal of cellular and nuclear debris, can be detected. These autoantibodies may play a pathogenic role in the development or perpetuation of autoimmunity in SLE.

Autoimmunity, spontaneous tumourigenesis, and IL-15 insufficiency in mice with a targeted disruption of the tumour suppressor gene Fus1

The Fus1 gene resides in the critical 3p21.3 human chromosomal region deleted in lung and breast cancers. Recently, the tumour suppressor properties of Fus1 were confirmed experimentally by intra-tumoural administration of Fus1 that suppressed experimental lung metastasis in mice. We generated Fus1-deficient mice that were viable, fertile, and demonstrated a complex immunological phenotype. Animals with a disrupted Fus1 gene developed signs of autoimmune disease, such as vasculitis, glomerulonephritis, anaemia, circulating autoantibodies, and showed an increased frequency of spontaneous vascular tumours. Preliminary analysis of immune cell populations revealed a consistent defect in NK cell maturation in Fus1 null mice that correlated with changes in the expression of IL-15. Injection of IL-15 into Fus1 knockout mice completely rescued the NK cell maturation defect. Based on these results, we propose the hypothesis that Fus1 deficiency affects NK cell maturation through the reduction of IL-15 production but does not directly alter their developmental capacity. Since acquired immunity was not affected in Fus1-deficient animals, we suggest a relationship between the Fus1 protein and the regulation of innate immunity via IL-15 production. The increased frequency of spontaneous cancers and the development of an autoimmune syndrome in Fus1 null mice imply that these mice could serve as a model for studying molecular mechanisms of anti-tumour immunity and autoimmunity.

Antibodies to the superantigenic site of HIV-1 gp120: Hydrolytic and binding activities of the light chain subunit

Antibodies (Abs) to the superantigenic determinant of HIV gp120 (gp120(SAg)) are potential protective agents against HIV infection. We report that the light chain subunits of Abs cloned from lupus patients using phage library methods bind and hydrolyze gp120(SAg) independent of the heavy chain. Unlike frequent gp120(SAg) recognition by intact Abs attributable to V(H) domain structural elements, the isolated light chains expressed this activity rarely. Four light chains capable of gp120(SAg) recognition were identified by fractionating phage displayed light chains using peptide probes containing gp120 residues 421-433, a gp120(SAg) component. Three light chains expressed non-covalent gp120(SAg) binding and one expressed gp120(SAg) hydrolyzing activity. The hydrolytic light chain was isolated by covalent phage fractionation using an electrophilic analog of residues 421-433. This light chain hydrolyzed a reporter gp120(SAg) substrate and full-length gp120. Other peptide substrates and proteins were hydrolyzed at lower rates or not at all. Consistent with the expected nucleophilic mechanism of hydrolysis, the light chain reacted selectively and covalently with the electrophilic gp120(SAg) peptide analog. The hydrolytic reaction entailed a fast initial step followed by a slower rate limiting step, suggesting rapid substrate acylation and slow deacylation. All four gp120(SAg)-recognizing light chains contained sequence diversifications relative to their germline gene counterparts. These observations indicate that in rare instances, the light chain subunit can bind and hydrolyze gp120(SAg) without the participation of the heavy chain. The pairing of such light chains with heavy chains capable of gp120(SAg) recognition represents a potential mechanism for generating protective Abs with enhanced HIV binding strength and anti-viral proteolytic activity.

Protein array autoantibody profiles for insights into systemic lupus erythematosus and incomplete lupus syndromes

The objective of this study was to investigate the prevalence and clinical significance of a spectrum of autoantibodies in systemic lupus erythematosus and incomplete lupus syndromes using a proteome microarray bearing 70 autoantigens. Microarrays containing candidate autoantigens or control proteins were printed on 16-section slides. These arrays were used to profile 93 serum samples from patients with systemic lupus erythematosus (SLE (n = 33), incomplete LE (ILE; n = 23), first-degree relatives (FDRs) of SLE patients (n = 20) and non-autoimmune controls (NC; n = 17). Data were analysed using the significance analysis of microarray (SAM) and clustering algorithms. Correlations with disease features were determined. Serum from ILE and SLE patients contained high levels of IgG autoantibodies to 50 autoantigens and IgM autoantibodies to 12 autoantigens. Elevated levels of at least one IgG autoantibody were detected in 26% of SLE and 19% of ILE samples; elevated IgM autoantibodies were present in 13% of SLE and 17% of ILE samples. IgG autoantibodies segregated into seven clusters including two specific for DNA and RNA autoantigens that were correlated with the number of lupus criteria. Three IgG autoantibody clusters specific for collagens, DNA and histones, were correlated with renal involvement. Of the four IgM autoantibody clusters, two were correlated negatively with the number of lupus criteria; none were correlated with renal disease. The IgG : IgM autoantibody ratios generally showed a stepwise increase in the groups following disease burden from NC to SLE. Insights derived from the expanded autoantibody profiling made possible with the antigen array suggest differences in autoreactivity in ILE and SLE. Determining whether the IgM aurotreactivity that predominates in ILE represents an early stage prior to IgG switching or is persistent and relatively protective will require further longitudinal studies.

Psychiatric manifestations in systemic lupus erythematosus

Psychiatric abnormalities are common in systemic lupus erythematosus (SLE) with a prevalence of 17% to 75%, reflecting different methods of patient selection and assessment, the different professional orientation of clinicians, and lack of an accepted consensus for diagnosing active neuropsychiatric lupus (NPSLE). The psychiatric syndromes included in the ACR Neuropsychiatric Lupus Nomenclature Committee criteria are cognitive dysfunction, acute confusional state (delirium), anxiety disorder, mood disorder, and psychosis. In SLE patients, identification of psychiatric phenomena and the generation of a differential diagnosis are crucial. Possible mechanisms include vascular injury and pathogenic antibodies. Treatment strategies are based on small case studies. The purpose of this review is to discuss clinical manifestations, pathogenesis and the present therapeutic options in psychiatric lupus.

To smell autoimmunity: Anti-P-ribosomal autoantibodies, depression, and the olfactory system

Central Nervous System involvement in Systemic Lupus Erythematosus (CNS-SLE) is very common and ranges between 25%-70% of the patients. The CNS involvement is listed in the ARA criteria for SLE diagnosis. CNS-SLE is associated with more than 20 different autoantibodies. Yet, remarkable among them are the anti-P-ribosomal antibodies (anti-PR). These autoantibodies directed mainly against the carboxy 22 amino acids of the PO, P1 P2 ribosomal phosphoproteins. They are capable of penetrating lived cells and inducing apoptotic changes as well as leading to inhibition of specific cytokine secretion. The titer of the autoantibodies correlate with disease activity, kidney involvement and hepatitis. In this review, the mechanisms involved in CNS involvement and its relationship with anti-P ribosomal antibodies will be described.

Anti-alpha-actinin antibodies: a new marker of lupus nephritis

The exact role of anti-ds (double stranded) DNA antibodies in the pathogenesis of kidney injury in lupus nephritis remains a focus of continuing investigation. One theory explaining the pathogenicity of anti-dsDNA antibodies in lupus nephritis is direct cross-reactivity with renal antigens. Several years ago, alpha-actinin was identified as a major cross-reactive target for pathogenic anti-dsDNA antibodies in murine SLE. Indeed, binding of a nephritogenic murine anti-dsDNA antibody was stronger to the alpha-actinin derived from a lupus prone mouse mesangial cell line as compared to alpha-actinin in a non-autoimmune mouse mesangial cell line. Furthermore, we recently showed that immunization of non-autoimmune mice with alpha-actinin induces anti-chromatin antibodies, glomerular IgG deposition and proteinuria. In humans, anti-alpha-actinin autoantibodies (Ab) were associated with anti-dsDNA Ab in SLE. In those patients, anti-alpha-actinin rather than anti-dsDNA Ab were significantly associated with glomerulonephritis and disease activity. The anti-alpha-actinin reactivity was associated with high avidity anti-dsDNA Ab. Moreover, the anti-alpha-actinin response was related to the actin-binding site of alpha-actinin. Taken together, these studies indicate that detection of anti-alpha-actinin Ab, in association with anti-dsDNA Ab, may constitute a new marker in lupus nephritis.

Immunization of nonautoimmune mice with DNA binding domains of the largest subunit of RNA polymerase I results in production of anti-dsDNA and anti-Sm/RNP antibodies

Antibodies against the N-terminal (NT) but not the basic domain (BD), DNA binding regions of the largest subunit (S1) of RNA polymerase I (RNAPI) were detected in the sera of MRL-lpr/lpr lupus mice. Antibodies against both RNAPI(S1)-NT and -BD, as well as other systemic lupus erythematosus (SLE) autoantigens (La, ribosomal P proteins and Sm/RNP) were produced by rabbits immunized with anti-DNA antibodies that had been affinity purified from SLE patients. Immunization of nonautoimmune mice (Balb/c) with RNAPI(S1)-NT, RNAPI(S1)-BD, or La in the form of GST fusion proteins, induced production of anti-double-stranded (ds) DNA and anti-Sm/RNP. GST-P1 did not induce an anti-dsDNA response in these mice. These results demonstrate that RNAPI(S1)-NT, RNAPI(S1)-BD and La can participate in an anti-autoantigen/anti-DNA antibody loop during an SLE-like autoimmune response.

Antigen-chip technology for accessing global information about the state of the body

Traditionally, immunologic diagnosis has been based on an attempt to correlate each disease with a specific immune reactivity, such as an antibody or a T-cell response to a single antigen specific for the disease entity. The state of the body, however, appears to be encoded by the immune system in collectives of reactivities and not by single reactivities. Here we describe our use of microarray technology and informatics to develop an antigen chip capable of detecting global patterns of antibodies binding to hundreds of antigens simultaneously. The patterns fashion diagnostic signatures.

Anti-chromatin (anti-nucleosome) antibodies

Chromatin is the native complex of histones and DNA found in the cell nucleus of eukaryotes. The fundamental subunit of chromatin is the nucleosome, which is composed of a core particle in which 146 bp of helical DNA are wrapped around an octamer made up of two H2A-H2B dimers that surround an H3-H4 tetramer. The prevalence of anti-chromatin (nucleosome) antibodies in systemic lupus erythematosus (SLE) varies from 50% to 90%, being similar to that of the classical positive LE cell. The presence of these antibodies can be used, in conjunction with clinical findings and other laboratory tests, to help in the diagnosis of SLE and drug induced lupus. The presence of anti-chromatin antibodies has also been linked to glomerulonephritis in SLE patients.

Effect of dsDNA binding to SmD-derived peptides on clinical accuracy in the diagnosis of systemic lupus erythematosus

Systemic lupus erythematosus is characterized by antibodies to a variety of intracellular self-antigens, such as dsDNA and Sm, and these serve as hallmarks in the diagnosis of systemic autoimmune diseases. Several studies have shown that SmD1 and SmD3 synthetic peptides represent highly functional antigens for autoantibody detection and thus for diagnostic applications. The present study analysed the technical and clinical accuracy of an anti-SmD1 (amino acids 83-119) and an anti-SmD3 (amino acids 108-122) ELISA for the detection of anti-Sm antibodies. Depending on the cut-off value of the SmD1 ELISA, we found a high degree of concordance between the two tests. At an optimized cut-off value of 100 units for SmD1 we found the same clinical sensitivity (12.5%) and specificity (100%) in a group of systemic lupus erythematosus patients (n = 48) and in controls (n = 99). The concordance at this cut-off value was 100% (P < 0.0001; chi2 = 127.61). Using a second panel of sera (n = 65) preselected based on positive anti-Sm results, we confirmed the high degree of concordance between the two assays. Using dsDNA-coated ELISA plates and biotinylated peptides we confirmed the high dsDNA binding properties for SmD1, which were significantly higher than the SmD3-derived peptide. However, no cross-linking of anti-dsDNA antibodies to SmD1 was observed after adding increasing amounts of dsDNA to anti-dsDNA positive, anti-SmD1 negative serum. We therefore conclude that the reported difference in the sensitivity is related to the different cut-off levels and not to the detection of anti-dsDNA antibodies bridged via dsDNA to the SmD1 peptide. Moreover, we found that a subpopulation of anti-Sm antibodies cross-reacted with SmD1 and SmD3. Taken together, the data indicate that both SmD peptide ELISAs represent accurate assays and may be used as important standards for the detection of anti-Sm antibodies.

B‐Cell Self‐Tolerance in Humans

Two mechanisms account for generation of the human antibody repertoire; V(D)J recombination during the early stages of B-cell development in the bone marrow and somatic mutation of immunoglobulin genes in mature B cells responding to antigen in the periphery. V(D)J recombination produces diversity by random joining of gene segments and somatic mutation by introducing random point mutations. Both are required to attain the degree of antigen receptor diversification that is necessary for immune protection: defects in either mechanism are associated with increased susceptibility to infection. However, the downside of producing enormous random diversity in the antibody repertoire is the generation of autoantibodies. To prevent autoimmunity B cells expressing autoantibodies are regulated by strict mechanisms that either modify the specificity of autoantibodies or the fate of cells expressing such antibodies. Abnormalities in B-cell self-tolerance are associated with a large number of autoimmune diseases, but the precise nature of the defects is less well defined. Here we summarize recent data on the self-reactive B-cell repertoire in healthy humans and in patients with autoimmunity.

Pathogenic mechanisms of anti-endothelial cell antibodies (AECA): their prevalence and clinical relevance

Anti‐endothelial cell antibodies (AECA) represent a heterogeneous family of autoantibodies directed against structural endothelial proteins, as well as antigens adhering to endothelial cells. Although AECA immunoassays still show a high‐interlaboratory variability, several findings suggest a pathogenic role of these autoantibodies in diseases characterized by endothelial damage. In this chapter, we analyze the knowledge about AECA prevalence, clinical relevance, and their pathogenic role in autoimmune diseases focusing in particular on systemic lupus erythematosus, antiphospholipid syndrome, systemic sclerosis (SSc), and systemic vasculitis.

Autoimmunity to protective molecules: is it the perpetuum mobile (vicious cycle) of autoimmune rheumatic diseases?

Apoptotic defects and impaired clearance of cellular debris are considered key events in the development of autoimmunity, as they can contribute to autoantigen overload and might be involved in the initiation of an autoimmune response. The C1q protein and mannose-binding lectin are activators of the complement system. The pentraxins are a group of highly conserved proteins including the short pentraxins, C-reactive protein and serum amyloid P, and the long pentraxin family member, pentraxin 3, all of which are involved in innate immunity and in acute-phase responses. In addition to their role in innate immunity and inflammation, each of these proteins participates in the removal of damaged and apoptotic cells. In this article, we discuss the clinical significance of different levels of these proteins, their role in the induction of or protection against autoimmunity, and the presence of specific autoantibodies against them in various autoimmune diseases.

Selective involvement of the amygdala in systemic lupus erythematosus

BACKGROUND

Antibodies specifically affect the amygdala in a mouse model of systemic lupus erythematosus (SLE). The aim of our study was to investigate whether there is also specific involvement of the amygdala in human SLE.

METHODS AND FINDINGS

We analyzed a group of 37 patients with neuropsychiatric SLE (NP-SLE), 21 patients with SLE, and a group of 12 healthy control participants with diffusion weighted imaging (DWI). In addition, in a subset of eight patients, plasma was available to determine their anti-NMDAR antibody status. From the structural magnetic resonance imaging data, the amygdala and the hippocampus were segmented, as well as the white and gray matter, and the apparent diffusion coefficient (ADC) was retrieved. ADC values between controls, patients with SLE, and patients with NP-SLE were tested using analysis of variance with post-hoc Bonferroni correction. No differences were found in the gray or white matter segments. The average ADC in the amygdala of patients with NP-SLE and SLE (940 x 10(-6) mm2/s; p = 0.006 and 949 x 10(-6) mm2/s; p = 0.019, respectively) was lower than in healthy control participants (1152 x 10(-6) mm2/s). Mann-Whitney analysis revealed that the average ADC in the amygdala of patients with anti-NMDAR antibodies (n = 4; 802 x 10(-6) mm2/s) was lower (p = 0.029) than the average ADC of patients without anti-NMDAR antibodies (n = 4; 979 x 10(-6) mm2/s) and also lower (p = 0.001) than in healthy control participants.

CONCLUSIONS

This is the first study to our knowledge to observe damage in the amygdala in patients with SLE. Patients with SLE with anti-NMDAR antibodies had more severe damage in the amygdala compared to SLE patients without anti-NMDAR antibodies.

Chimerism in systemic lupus erythematosus—three hypotheses

Systemic lupus erythematosus (SLE) is an immune-mediated disease characterized by the presence of autoantibodies and a wide array of clinical symptoms. Despite intensive research, the aetiology of SLE is still unknown and is probably multifactorial. Both genetic and environmental factors have been associated with SLE, but these factors alone are insufficient to explain the onset of SLE. Recently, it has been suggested that chimerism plays a role in the pathogenesis of autoimmune diseases, including SLE. Chimerism indicates the presence of cells from one individual in another individual. In an experimental mouse model, the injection of chimeric cells induces a lupus-like disease. In addition, chimerism is found more often in kidneys of women with SLE than in healthy controls. There are several mechanisms by which chimeric cells could be involved in the pathogenesis of SLE. In this review, three hypotheses on the role of chimerism in SLE are discussed. The first two hypotheses describe the possibilities that chimeric cells induce either a graft-vs-host reaction in the host (comparable with reactions seen after bone marrow transplantation) or a host-vs-graft reaction (comparable with reactions seen after solid organ transplantation). The third hypothesis discusses the possible beneficial role chimeric cells may play in repair mechanisms due to their stem cell-like properties. This review provides insights into the mechanisms by which chimerism may be involved in SLE and proposes several lines of inquiry to further investigate chimerism in SLE.

Effects of sleep deprivation on the development of autoimmune disease in an experimental model of systemic lupus erythematosus

Sleep is hypothesized to play a restorative role on immune system. In addition, disturbed sleep is thought to impair host defense mechanisms. Chronic sleep deprivation is a common occurrence in modern society and has been observed in a number of chronic inflammatory conditions, such as systemic lupus erythematosus (SLE). New Zealand Black/New Zealand White (NZB/NZW) F1mice develop an autoimmune disease that strongly resembles SLE in humans, exhibiting high titers of antinuclear antibodies associated with the development of rapidly progressive and lethal glomerulonephritis. On the basis of this evidence, the present study examined the onset and progress of lupus in as-yet healthy female mice submitted to sleep deprivation. Sleep deprivation was accomplished by two 96-h periods in the multiple-platform method when mice were 10 wk old, and they were observed until 28 wk of age. Blood samples were collected from the orbital plexus fortnightly to evaluate serum antinuclear antibodies and anti-double-stranded DNA. Proteinuria and longevity as well as body weight were also assessed. The results indicated that mice submitted to sleep deprivation exhibited an earlier onset of the disease, as reflected by the increased number of antinuclear antibodies. However, no statistical difference was found in the other parameters analyzed. According to these results, sleep deprivation could be considered as a risk factor for the onset but not for the evolution of the disease.

Clinical and biological aspects of anti-P-ribosomal protein autoantibodies

Among the many clinical manifestations of systemic lupus erythematosus (SLE), central nervous system (CNS) involvement is of a prognostic importance. In this respect, anti-ribosomal P protein antibodies were shown by many to occur in association with SLE neuropsychiatric manifestations, mainly psychosis. The prevalence of anti-P antibodies was strongly related to disease activity wherein disease remission was associated with the disappearance of these antibodies. In addition to its association with CNS involvement, the occurrence of liver and kidney disease in SLE patients with anti-P antibodies was widely reported. Anti-P antibodies are able to bind T cells, monocytes, neurons and hepatocytes thereby enhancing the production of pro-inflammatory cytokines and both CNS and liver damage. Similar to the ability of anti-dsDNA antibodies, anti-P antibodies were shown to penetrate into living cells, leading to cell dysfunctions such as cell apoptosis. These biological aspects may play an important role in the pathogenesis of SLE.

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.

Antinucleosome antibodies correlate with the disease severity in children with systemic lupus erythematosus

We compared the serum levels of antinucleosome antibodies (anti-NCS Abs) in thirty pediatric systemic lupus erythematosus (SLE) patients by using enzyme-linked immunosorbent assay (ELISA) to 29 adult SLE patients, 30 healthy controls, 21 juvenile idiopathic arthritis (JIA) and 23 Henoch-Schonlein purpura (HSP) patients as autoimmune disease controls. The mean anti-NCS Ab titer in the pediatric SLE patients was 1552.7+/-1842.2 U/ml, higher than those of adult SLE patients (194.3+/-402.7 U/ml), normal controls (9.5+/-5.7 U/ml) and disease controls (JIA: 7.7+/-4.0 U/ml, HSP: 5.7+/-4.4 U/ml) (p<0.05). The prevalence of both anti-NCS Ab (90%) and anti-ds DNA Ab (76.7%) in pediatric SLE patients were higher (p<0.05) than that of adult SLE patients (58.6% and 48.3%). A positive correlation was demonstrated between anti-NCS Ab and anti-dsDNA Ab as well as the SLEDAI scores in pediatric and adult patients (p<0.05). The inverse correlation of anti-NCS Ab levels with C3 was observed in both pediatric and adult SLE patients (pediatrics, r=-0.61, p=0.0003; adult, r=-0.44, p=0.02). Our data suggested that in pediatric SLE patients, anti-NCS Ab could be as good a marker for SLE diagnosis and disease activity assessment as in adult SLE patients.

Application of a static fluorescence-based cytometer: the CellScan in clinical immunology

The CellScan system is a laser scanning cytometer which enables repetitive fluorescence intensity (FI) and polarization (FP) measurements in living cells, as a means of monitoring lymphocyte activation. By monitoring FP changes in peripheral blood lymphocytes (PBL) following exposure to antigenic stimuli, the CellScan may have a role in the diagnosis of autoimmune diseases. Monitoring changes in FI and FP in PBLs from patients with atherosclerosis following exposure to various stimuli, has illustrated the role of the immune system in the atherosclerotic process. The CellScan has also been evaluated as a diagnostic tool for drug-induced allergy, based on FP reduction in PBLs following incubation with the suspected drugs. FI and FP changes in cancer cells have been found to correlate with the cytotoxic effect of different anti-neoplastic drugs, illustrating the potential role of the CellScan system in clinical oncology. In conclusion, the CellScan is a promising new tool with a variety of applications in cell biology, immunology, cancer research and clinical pharmacology.

Serum antiguanosine antibodies as a marker for SLE disease activity and pathogen potential

BACKGROUND

This article reviews research conducted on the immunogenicity of the nucleosides of DNA, especially guanosine, the most immunologically active nucleoside. Discussed is the relationship between circulating antibodies to guanosine, their potential role in SLE disease activity, the binding properties of monoclonal antiguanosine antibody (4H2) compared to polyclonal antiguanosine antibodies in humans with SLE, cell membrane penetration by these antibodies and their interference with signal transduction possibly related to their binding to mitochondria and their apparent GTPase activity.

METHODS

Enzyme-linked immunosorbent assay methodology was used to show clinical relationships between antiguanosine antibody levels and disease activity in SLE. These results are discussed along with methods of detecting cell penetration by this antibody using special staining techniques, laser-scanning microscope detection of mitochondrial localization, and interference of cAMP and pKA production/activation. Additionally, there is some discussion regarding the assay used to detect enzymatic activity of antiguanosine antibodies.

RESULTS

Enhanced circulating levels of antiguanosine antibodies in patients with SLE correlate closely with SLE disease activity. Other factors are discussed that support the pathogenic potential of these antibodies, including their ability to penetrate lymphocytes, bind to mitochondria, inactivate mitochondrial function, interfere with signal transduction, and their potential enzymatically activity.

CONCLUSIONS

Antiguanosine antibodies correlate with SLE disease activity and may be pathogenically important in SLE by interfering with signal transduction, inactivating mitochondrial and cell function in patients with SLE.

Non-DNA-Binding Antibodies in Patients with Lupus Nephritis Could Recognize Membrane Proteins of Glomerular Mesangial Cells

Lupus nephritis (LN) is a prototypic autoimmune disease, however, the precise immuno-pathogenesis of LN remains to be elucidated. In our previous studies, autoantibodies against mesangial cells had been identified in sera from patients with lupus nephritis and could bind the membrane proteins of human mesangial cells (HMC) directly through antigen-antibody interaction without DNA bridge. The current study is to investigate whether the autoantibodies were associated with anti-DNA antibodies and their target antigens distribution in different cell types. Sera from nine patients with renal biopsy proven lupus nephritis with positive anti-dsDNA antibodies and four healthy subjects were collected. IgG was isolated by Protein G affinity chromatography and then non-DNA-binding IgG fractions were obtained after deletion of anti-DNA antibodies using a DNA-cellulose affinity column. Membrane proteins, obtained from HMC, human umbilical vein endothelial cells (HUVEC), peripheral mononuclear cells by sonication and sequential centrifugation, were solubilized and applied in Western-blot analysis to characterize the target antigens. In results, the non-DNA-binding IgG fractions from sera of patients with lupus nephritis could blot the protein(s) of HMC membrane at 74, 63, and 42 kD. However, only a similar 74-kD protein could be blotted on membrane of HUVEC, and the target antigens on membranes of mononuclear cells were heterogeneous. In conclusion, our preliminary study had demonstrated that non-DNA binding autoantibodies against mesangial cells could be found in sera from patients with lupus nephritis. Although the target antigens might not be cell specific, the roles of these autoantibodies in the pathogenesis of lupus nephritis need further investigation.

The in vivo expression of actin/salt-resistant hyperactive DNase I inhibits the development of anti-ssDNA and anti-histone autoantibodies in a murine model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterised by the production of autoantibodies against ubiquitous antigens, especially nuclear components. Evidence makes it clear that the development of these autoantibodies is an antigen-driven process and that immune complexes involving DNA-containing antigens play a key role in the disease process. In rodents, DNase I is the major endonuclease present in saliva, urine and plasma, where it catalyses the hydrolysis of DNA, and impaired DNase function has been implicated in the pathogenesis of SLE. In this study we have evaluated the effects of transgenic over-expression of murine DNase I endonucleases in vivo in a mouse model of lupus. We generated transgenic mice having T-cells that express either wild-type DNase I (wt.DNase I) or a mutant DNase I (ash.DNase I), engineered for three new properties – resistance to inhibition by G-actin, resistance to inhibition by physiological saline and hyperactivity compared to wild type. By crossing these transgenic mice with a murine strain that develops SLE we found that, compared to control non-transgenic littermates or wt.DNase I transgenic mice, the ash.DNase I mutant provided significant protection from the development of anti-single-stranded DNA and anti-histone antibodies, but not of renal disease. In summary, this is the first study in vivo to directly test the effects of long-term increased expression of DNase I on the development of SLE. Our results are in line with previous reports on the possible clinical benefits of recombinant DNase I treatment in SLE, and extend them further to the use of engineered DNase I variants with increased activity and resistance to physiological inhibitors.