Ribosomal P antibodies and CNS lupus

Autoantibodies in Neuropsychiatric Systemic Lupus Erythematosus (NPSLE): Can They Be Used as Biomarkers for the Differential Diagnosis of This Disease?

Systemic lupus erythematosus is a complex immunological disease where both environmental factors and genetic predisposition lead to the dysregulation of important immune mechanisms. Eventually, the combination of these factors leads to the production of self-reactive antibodies that can target any organ or tissue of the human body. Autoantibodies can form immune complexes responsible for both the organ damage and the most severe complications. Involvement of the central nervous system defines a subcategory of the disease, generally known with the denomination of neuropsychiatric systemic lupus erythematosus. Neuropsychiatric symptoms can range from relatively mild manifestations, such as headache, to more severe complications, such as psychosis. The evaluation of the presence of the autoantibodies in the serum of these patients is the most helpful diagnostic tool for the assessment of the disease. The scientific progresses achieved in the last decades helped researchers and physicians to discover some of autoepitopes targeted by the autoantibodies, although the majority of them have not been identified yet. Additionally, the central nervous system is full of epitopes that cannot be found elsewhere in the human body, for this reason, autoantibodies that selectively target these epitopes might be used for the differential diagnosis between patients with and without the neuropsychiatric symptoms. In this review, the most relevant data is reported with regard to mechanisms implicated in the production of autoantibodies and the most important autoantibodies found among patients with systemic lupus erythematosus with and without the neuropsychiatric manifestations.

Evaluation of depression and general health assessment among systemic lupus erythematosus patients in relation to disease activity and damage

Background

Systemic lupus erythematosus (SLE) is a chronic autoimmune illness defined by involvement of several systems and a variety of clinical symptoms among them the neuropsychiatric manifestations. The purpose of the study was to evaluate the presence of depression and to assess overall health in individuals with SLE, as well as their relation to SLE disease activity and damage. Sixty adult SLE patients were enrolled, along with sixty age and sex-matched controls. For the presence of major depression, all patients were examined using the Beck Depression Inventory (BDI-II) and the General Health Questionnaire (GHQ-12) for mental distress. Antinuclear antibody, anti-ds DNA, complements 3 and 4, and anti-ribosomal P antibody were performed for SLE patients. The SLEDAI-2 K and SLEDDI were assessed.

Results

The 60 patients were 52 (86.7%) females and 8 (13.3%) men, with a mean age of 32.5 ± 11.5 years and disease duration of 3.57 ± 3.55 years. Patients with depression accounted for 43 (71.6%) of the total, whereas controls accounted for just 14 (23.3%). Patients with substantial depression had significantly higher SLEDAI-2 K, SLEDDI, and illness duration than those without major depression (p = 0.047, p = 0.043, and p = 0.033, respectively). The patients’ mean GHQ-12 score was 17 ± 5.96, whereas the control group's was 10.0 ± 67.30, with a p value of 0.002. SLEDAI-2 K, SLEDDI, and depression score had a substantial positive association (p = 0.001, p = 0.042), while BDI-II and GHQ-12 had a significant positive correlation (p 0.001).

Conclusions

Depression and psychological distress were both common in SLE patients. Depression severity was linked to illness duration, activity, and damage.

The immunologic etiology of psychiatric manifestations in systemic lupus erythematosus: A narrative review on the role of the blood brain barrier, antibodies, cytokines and chemokines

INTRODUCTION

The aim of this narrative review is to provide an overview of the literature on the possible immunologic pathophysiology of psychiatric manifestations of neuropsychiatric systemic lupus erythematosus (NPSLE).

METHODS

A systematic search on PubMed was conducted. English studies with full text availability that investigated the correlation between blood-brain barrier (BBB) dysfunction, intrathecal synthesis of antibodies, antibodies, cytokines, chemokines, metalloproteinases, complement and psychiatric NPSLE manifestations in adults were included.

RESULTS

Both transient BBB-dysfunction with consequent access of antibodies to the cerebrospinal fluid (CSF) and intrathecal synthesis of antibodies could occur in psychiatric NPSLE. Anti-phospholipid antibodies, anti-NMDA antibodies and anti-ribosomal protein p antibodies seem to mediate concentration dependent neuronal dysfunction. Interferon-α may induce microglial engulfment of neurons, direct neuronal damage and production of cytokines and chemokines in psychiatric NPSLE. Several cytokines, chemokines and matrix metalloproteinase-9 may contribute to the pathophysiology of psychiatric NPSLE by attracting and activating Th1-cells and B-cells.

DISCUSSION

This potential pathophysiology may help understand NPSLE and may have implications for the diagnostic management and therapy of psychiatric NPSLE. However, the presented pathophysiological model is based on correlations between potential immunologic etiologies and psychiatric NPSLE that remain questionable. More research on this topic is necessary to further elucidate the pathophysiology of NPSLE.

Clinical Factors Associated with Brain Volume Reduction in Systemic Lupus Erythematosus Patients without Major Neuropsychiatric Manifestations

The aim of the study was to find structural brain changes in systemic lupus erythematosus patients without major neuropsychiatric manifestations [non-neuropsychiatric systemic lupus erythematosus (non-NPSLE)] using quantitative magnetic resonance imaging (MRI) and possible associations with clinical characteristics. 89 non-NPSLE patients with normal conventional MRI and 84 healthy controls (HCs) were recruited. The whole brain gray matter volume (GMV) and white matter volume (WMV) were calculated for each individual. We found obvious GMV and WMV reduction in the systemic lupus erythematosus (SLE) group compared with HCs. Female patients showed significant reduction of GMV and WMV compared with male patients. Patients treated with immunosuppressive agents (ISA) showed less WMV reduction than those without. Cognitive impairment was the most common subclinical neuropsychiatric manifestation and had a prevalence of 46.1%. Association between WMV reduction with cognitive impairment was found. Thus, we concluded that structural brain atrophy could happen even before occurrence of obvious neuropsychiatric signs and symptoms and was associated with subclinical symptoms such as cognitive impairment. ISA treatment might have a protective effect on the brain atrophy. Early treatment might prevent the progressive damage to the brain. More studies are needed to fully understand the complicated underlying mechanisms of brain atrophy in SLE.

Immune Cell Neurotrophin Production Is Associated with Subcortical Brain Atrophy in Neuropsychiatric Systemic Lupus Erythematosus Patients

OBJECTIVE

Central nervous system (CNS) involvement in systemic lupus erythematosus (SLE) remains poorly understood. Damage within the CNS is driven by the autoimmune response; however, immunopathophysiology of neuropsychiatric (NP) SLE is multifactorial. Immune cell neurotrophin production could be neuroprotective against autoimmunity-driven CNS damage, as has been shown in multiple sclerosis. The aim of this study was to establish whether immune cell neurotrophin production is associated with damage severity in NPSLE.

METHODS

Selected neurotrophins (BDNF, NGF, NT-3, and NT-4/5) were measured with ELISA within peripheral blood mononuclear cells (PBMCs) isolated from 38 NPSLE patients matched with 39 healthy controls. Subcortical and cortical structure volumes were segmented with the Freesurfer 5.3 pipeline on T1-weighted isotropic images acquired on a 1.5-T MRI scanner.

RESULTS

BDNF and NGF levels in PBMCs were reduced in NPSLE compared to the healthy population. The PBMC BDNF level was associated with reduced thalamus, caudate, and putamen volumes. The NGF level correlated with lateral ventricles enlargement and thalamic volume loss.

CONCLUSIONS

In NPSLE, immune cell BDNF and NGF levels are linked with subcortical atrophy. Higher BDNF levels are associated with higher midsagittal atrophy, which may reflect compensatory mechanisms, upregulating BDNF when neuroprotection is needed. These data require further confirmation.

Autoantibodies Affect Brain Density Reduction in Nonneuropsychiatric Systemic Lupus Erythematosus Patients

This study explores the relationship between autoantibodies and brain density reduction in SLE patients without major neuropsychiatric manifestation (NPSLE). Ninety-five NPSLE patients without obvious cerebral deficits, as determined by conventional MRI, as well as 89 control subjects, underwent high-resolution structural MRI. Whole-brain density of grey matter (GMD) and white matter (WMD) were calculated for each individual, and correlations between the brain density, symptom severity, immunosuppressive agent (ISA), and autoantibody levels were assessed. The GMD and WMD of the SLE group decreased compared to controls. GMD was negatively associated with SLE activity. The WMD of patients who received ISA treatment were higher than that in the patients who did not. The WMD of patients with anticardiolipin (ACL) or anti-SSB/La antibodies was lower than in patients without these antibodies, while the GMD was lower in patients with anti-SM or anti-U1RNP antibodies. Thus, obvious brain atrophy can occur very early even before the development of significant symptoms and specific autoantibodies might contribute to the reduction of GMD or WMD in NPSLE patients. However, ISAs showed protective effects in minimizing GMD and WMD reduction. The presence of these specific autoantibodies might help identify early brain damage in NPSLE patients.

Identification of novel autoantibodies to GABA(B) receptors in patients with neuropsychiatric systemic lupus erythematosus

OBJECTIVE

The gamma-aminobutyric acid type B receptors (GABAR(B)) are G-protein coupled receptors for GABA, the main inhibitory neurotransmitter in the brain. We identified GABAR(B) subunits as candidate antigens in patients with SLE using a random peptide display library. The aim of this study was to investigate the possible link between anti-GABAR(B) antibodies and disease activity and NPSLE.

METHODS

ELISA was performed with recombinant proteins of GABAR(B1b) and GABAR(B2) on serum samples from patients with SLE (n = 88), scleroderma (n = 20), myositis (n = 20) or vasculitis (n = 20) as well as healthy subjects (n = 20). Cerebrospinal fluid (CSF) from 23 patients with SLE was also examined.

RESULTS

Autoantibodies to GABAR(Bs) were exclusive to patients with SLE (P < 0.001) and positively associated with SLEDAI (anti-GABAR(B1b), P = 0.001; anti-GABAR(B2), P < 0.001). Of note, autoantibodies were positively linked with NPSLE (anti-GABAR(B1b), P = 0.02; anti-GABAR(B2), P = 0.03). Moreover, anti-GABAR(Bs) was detected in 61.5% of CSF samples from patients with active NPSLE, a frequency that was significantly higher than that for patients with non-SLE syndromes.

CONCLUSION

Anti-GABAR(B) antibodies could represent novel candidate markers for disease activity and NPSLE.

B-cell-targeted therapies in systemic lupus erythematosus

Autoreactive B cells are one of the key immune cells that have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). In addition to the production of harmful auto-antibodies (auto-Abs), B cells prime autoreactive T cells as antigen-presenting cells and secrete a wide range of pro-inflammatory cytokines that have both autocrine and paracrine effects. Agents that modulate B cells may therefore be of potential therapeutic value. Current strategies include targeting B-cell surface antigens, cytokines that promote B-cell growth and functions, and B- and T-cell interactions. In this article, we review the role of B cells in SLE in animal and human studies, and we examine previous reports that support B-cell modulation as a promising strategy for the treatment of this condition. In addition, we present an update on the clinical trials that have evaluated the therapeutic efficacy and safety of agents that antagonize CD20, CD22 and B-lymphocyte stimulator (BLyS) in human SLE. While the results of many of these studies remain inconclusive, belimumab, a human monoclonal antibody against BLyS, has shown promise and has recently been approved by the US Food and Drug Administration as an indicated therapy for patients with mild to moderate SLE. Undoubtedly, advances in B-cell immunology will continue to lead us to a better understanding of SLE pathogenesis and the development of novel specific therapies that target B cells.

The use of electroconvulsive therapy in a patient with juvenile systemic lupus erythematosus and catatonia

Catatonia is a rare manifestation in patients with systemic lupus erythematosus (SLE). As catatonia can be associated with both psychiatric and organic conditions, this could create a diagnostic dilemma once this occurs in SLE patients. The report describes a 15-year-old female with SLE who developed catatonia three days after the diagnosis of SLE was made. Her catatonia was refractory to the treatment with immunosuppressive therapy, which included pulse methylprednisolone, intravenous cyclophosphamide, rituximab, intravenous immunoglobulin (IVIG) and plasmapheresis. Given her persistent catatonia, electroconvulsive therapy (ECT) was initiated three months after the onset of her symptoms. After the third ECT treatment, her mental status dramatically improved and returned nearly to baseline while she was continued on the immunosuppression. This is the first report of a successful ECT therapy in catatonic lupus in children.

The efficacy of brain F-fluorodeoxyglucose positron emission tomography in neuropsychiatric lupus patients with normal brain magnetic resonance imaging findings

Brain involvement in systemic lupus erythematosus (SLE) is a significant source of morbidity and mortality. Therefore, the early detection and treatment of brain involvement in SLE is of utmost importance; however, a confirmative diagnostic tool for neuropsychiatric SLE is yet to be developed. In this study, we investigated the efficacy of 18F-FDG-PET for detection of brain involvement in patients with SLE with normal magnetic resonance imaging (MRI) findings. Twenty patients with SLE, who presented with neuropsychiatric symptoms despite normal brain MRI findings and who underwent brain 18F-FDG-PET, were enrolled. The most common neuropsychiatric manifestation was headache (45%), followed by seizure (20%) and mood disorder (20%). 18F-FDG-PET revealed significant glucose metabolic abnormalities in 15 of 20 patients (75%). The temporal (55%) and the occipital (55%) lobes were the most susceptible brain regions, followed by the frontal lobe (50%). However, neuropsychiatric symptoms were not geographically correlated to 18F-FDG-PET findings. Two patients with abnormal 18F-FDG-PET findings underwent follow-up brain 18F-FDG-PET after remission, which showed complete resolution of abnormal glucose metabolism. Our data suggest that 18F-FDG-PET may be an additional diagnostic modality complementary to MRI, when MRI is unable to provide evidence of brain involvement in patients with SLE.

Autoantibody-dependent and autoantibody-independent roles for B cells in systemic lupus erythematosus: past, present, and future

It has long been known that B cells produce autoantibodies and, thereby, contribute to the pathogenesis of many autoimmune diseases. Systemic lupus erythematosus (SLE), a prototypic systemic autoimmune disorder, is characterized by high-circulating autoantibody titers and immune-complex deposition that can trigger inflammatory damage in multiple organs/organ systems. Although the interest in B cells in SLE has historically focused on their autoantibody production, we now appreciate that B cells have multiple autoantibody-independent roles in SLE as well. B cells can efficiently present antigen and activate T cells, they can augment T cell activation through co-stimulatory interactions, and they can produce numerous cytokines which affect inflammation, lymphogenesis, and immune regulation. Not surprisingly, B cells have become attractive therapeutic targets in SLE. With these points in mind, this review will focus on the autoantibody-dependent and autoantibody-independent roles for B cells in SLE and on therapeutic approaches that target B cells.

Cross-talk of the environment with the host genome and the immune system through endogenous retroviruses in systemic lupus erythematosus

Environmental factors are capable of triggering the expression of human endogenous retroviruses and induce an autoimmune response. Infection can promote the expression of human endogenous retroviruses by molecular mimicry or by functional mimicry. There are additional mechanisms which may control the expression of human endogenous retroviruses, such as epigenetic status of the genome (hypomethylation, histone deacetylation). Ultraviolet exposure, chemicals/drugs, injury/stress, hormones, all as a single cause or in a concert, may modulate the involvement of human endogenous retroviruses in pathogenic processes. In the current review we summarize the current knowledge on infections, molecular mimicry, cross-reactivity and epigenetics contribution for trigger human endogenous retroviruses expression and pathogenesis in lupus patients. Lupus (2009) 18, 1136—1143.

Anti-proteasome activator 28alpha is a novel anti-cytoplasmic antibody in patients with systemic lupus erythematosus and Sjögren's syndrome

We evaluated the extent to which anti-proteasome activator (PA) 28alpha antibodies act as anti-cytoplasmic antibodies in systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS). Sera from 46 SLE patients without SS, 11 SLE patients with SS, and 45 primary SS patients were tested. Using anti-PA28alpha and anti-PA28gamma (Ki) antibodies purified from nitrocellulose membranes onto which recombinant PA28alpha and Ki had been transferred, the cellular distributions of the targeted antigens were analyzed immunohistochemically. In addition, the incidence of anti-PA28alpha antibodies was compared with those of other anti-cytoplasmic antibodies. Immunofluorescent staining showed that purified anti-PA28alpha antibodies reacted with the cytoplasm of HEp-2 cells, whereas purified anti-Ki antibodies reacted with nucleoplasm. Among the 15 SLE patients without SS, the six SLE patients with SS, and the 30 primary SS patients who were anti-cytoplasmic-antibody positive, anti-SS-A/Ro antibodies were the most frequently detected (53, 67, and 70%, respectively); anti-PA28alpha antibodies were, respectively, detected in 33, 50, and 40% of those patient groups, incidences that were higher than those of anti-ribosomal P, anti-smooth muscle and anti-mitochondrial M2 antibodies. These results show that anti-PA28alpha antibodies are major anti-cytoplasmic antibodies in patients with SLE and SS, and the distinct cellular distributions of PA28alpha and Ki suggest these proteins are associated with different cellular functions.

Autoantibodies involved in neuropsychiatric manifestations associated with systemic lupus erythematosus

In the course of Systemic Lupus Erythematosus (SLE), a variety of neuropsychiatric disturbances is reported with a prevalence ranging from 17% to 75%. The diagnosis of these syndromes is difficult and requires a careful psychiatric evaluation. Distinct autoantibodies detectable in serum or cerebrospinal fluid of patients with SLE are associated with the presence of neuropsychiatric disorders. These autoantibodies may have a pathogenic relevance in neuropsychiatric SLE or they may be merely an epiphenomenon. This review describes the various autoantibodies reported to be associated with neuropsychiatric manifestations in SLE and discusses their possible role.

Autoantibodies against galectin-8: their specificity, association with lymphopenia in systemic lupus erythematosus and detection in rheumatoid arthritis and acute inflammation

The role of autoantibodies in the pathogenesis of systemic lupus erythematosus (SLE) has not been completely defined. From more than a hundred autoantibodies described in SLE, relatively few have been associated with clinical manifestations. The glycan-binding proteins of the galectin family can modulate the immune system. Anti-galectin autoantibodies thus could have functional and/or pathogenic implications in inflammatory processes and autoimmunity. We previously reported function-blocking autoantibodies against galectin-8 (Gal-8) in SLE. Here we tested these autoantibodies against a series of other human galectins and demonstrated their specificity for Gal-8, being detectable in 23% of 78 SLE patients. Remarkably, they associated with lymphopenia (50% of 18 anti-Gal-8-positive versus 18% of 60 anti-Gal-8-negative cases, Fisher’s Exact test two-tailed: P < 0.012). Lymphopenia is a common clinical manifestation in SLE, yet of unknown mechanism. In addition, six of eight patients with both lymphopenia and malar rash had anti-Gal-8 in their sera. Occurrence of these autoantibodies was not confined to SLE as we also found them in sera of patients with rheumatoid arthritis (16%) and septicemia (20%). This study thus establishes occurrence of specific anti-Gal-8 autoantibodies in autoimmune rheumatic diseases and in acute inflammation, with an apparent association to a clinical subset in SLE.

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.

Are anti-ribosomal P protein antibodies relevant in systemic lupus erythematosus?

Systemic lupus erythematosus (SLE) is a prototypal auto-immune disorder characterized with multiple organ involvement resulting in disability and increased mortality. Immune regulatory disturbances cumulate in activation of B cells and consequent auto-antibody production. Antigens for these auto-antibodies can be nuclear components and cytoplasmic elements. Anti-P antibodies react against acidic phosphorylated ribosomal proteins P0, P1, and P2 (with molecular mass of 38, 19, and 17 kDa, respectively) and are located on the S60 subunit of ribosomes. Ribosomal P proteins share a common 22-amino acid sequence that is present in the carboxyl-terminal. Anti-P antibodies can be detected in approx 15 to 20% of patients with lupus by several immunoassays, most frequently by enzyme-linked immunosorbent assay (ELISA) and/or Western blotting. However, no standardized assay is available. Auto-antibodies against eukaryotic P proteins appear highly specific for SLE; therefore, they can be used as diagnostic marker for the disease. Furthermore, association has been described with particular manifestations of lupus, especially with neuropsychiatric, renal, and hepatic involvements. Anti-P positivity and the titer of anti-P antibodies also fluctuate with clinical disease activity. Despite several lines of evidence, results are conflicting regarding the existence of such associations. Discrepancies can be explained by different study set-up or study population; it also can be attributed to the different sensitivity of tests used for the detection of anti-P antibody.

Acute psychosis in systemic lupus erythematosus

To evaluate the frequency and risk factors of acute psychosis in a large cohort of patients with systemic lupus erythematosous (SLE). To identify clinical and laboratory variables useful in differentiating acute psychosis as a primary manifestation of central nervous system (CNS) from corticosteroid induced psychosis. Five hundred and thirty seven consecutive patients with SLE were studied, with follow-up ranging from 4 to 8.8 years. A standardized medical history, neurological, rheumatologic, and psychiatric examinations and serologic testing were performed in all patients. The type and frequency of risk factors associated with acute psychosis as a primary manifestation of CNS system and corticosteroid induced psychosis was determined using multivariate regression with automatic backward stepwise selection. We identified acute psychosis in 89 of 520 (17.1%) SLE patients. Psychosis primary to CNS involvement was diagnosed in 59 of these patients, corticosteroid induced psychosis in 28 and primary psychotic disorder not related to SLE or medication in two patients. Psychosis secondary to SLE at disease onset occurred in 19 patients and was associated with disease activity (p = 0.001; OR = 2.4; CI = 1.5-6.2). Psychosis during follow-up of SLE was observed in 40 patients and associated with positive antiphospholipid antibodies (p = 0.004; OR = 3.2; CI = 1.9-4.5) and less frequently with renal (p = 0.002; OR = 1.9; CI = 0.0-0.6) and cutaneous (p = 0.04; OR = 1.1; CI = 0.0-0.8) involvement. We identified 28 patients with 38 episodes of psychosis associated with corticosteroid therapy. All the patients had severe active disease and ten of these patients had hypoalbuminemia when psychosis developed. At the time of psychotic event, all the patients were taking prednisone in doses varying from 0.75 to 1 mg/kg day(-1). Psychosis resolved after tapering prednisone down in all patients. Acute psychosis related to SLE was observed in 11.3% of our cohort. Recurrence of primary psychosis was associated with other CNS manifestations related to SLE.

Notes on the kidney and its diseases for the neurologist

To save their patients from dialysis and transplantation, neurologists need simply remain alert to the possibility of renal failure, particularly in the context of systemic disease, diabetes, sepsis and drugs. Of the numerous territories shared by our respective specialities, we outline a pragmatic approach to the diagnosis and treatment of the vasculitides, underpinned by knowing which questions to ask, equally importantly when to ask them, and in the art of obtaining a tissue diagnosis. We consider the current evolving trial evidence that directs the usage of a growing arsenal of therapies in the induction and maintenance stages of vasculitis treatment, and extend this consideration to Lupus and Sjogren's.

Autoantibodies Involved in Neuropsychiatric SLE and Antiphospholipid Syndrome

OBJECTIVE

We sought (1) to identify and (2) to define the association of all reported antibodies (Abs) with neuropsychiatric lupus (NPSLE), (3) to search for possible mechanisms that are involved in NPSLE, and (4) to determine whether we can recognize a panel of Abs associated with specific neuropsychiatric (NP) manifestations.

METHODS

A MEDLINE search (1975 to 2005) was performed utilizing the following terms: neuropsychiatric lupus, antiphospholipid syndrome, or central nervous system systemic lupus erythematosus matched with the term antibodies.

RESULTS

Twenty Abs (11 brain-specific and 9 systemic) were described in NPSLE patients. These include Abs that target brain-specific antigens (neuronal, ganglioside, synaptosomes, glia, methyl-d-aspartate receptors, lymphocytotoxic) and systemic antigens (nuclear, cytoplasmic, phospholipid, endothelial cells). Cognitive impairment, psychosis, and depression were associated with many Abs. Elevated titers of anticardiolipin Abs (aCL) were reported most often and found in patients with cognitive impairment, psychosis, depression, seizures, chorea, and migraine. No specificity was encountered among brain-specific or systemic Abs for any single NP manifestation. No studies evaluated a specific NP manifestation with the full panel of 20 Abs. A panel of brain-specific and systemic Abs may be helpful in establishing the diagnosis of NPSLE. Postulated mechanisms in experimental models included vascular occlusion and injury by pathogenic Abs in a disrupted blood brain barrier.

CONCLUSIONS

NPSLE is associated with brain-specific and systemic Abs. Cognitive impairment, psychosis, and depression were associated with many Abs, including aCL Abs. Possible mechanisms include vascular occlusion and injury by pathogenic Abs in a disrupted blood brain barrier.

Induction of autoimmune depression in mice by anti–ribosomal P antibodies via the limbic system

OBJECTIVE

Autoantibodies against ribosomal P proteins are linked to the neuropsychiatric manifestations of systemic lupus erythematosus (SLE). The present study was undertaken to assess how the specific brain-binding autoantibody anti-ribosomal P can induce a depression-type psychiatric disorder in mice.

METHODS

Mice were injected intracerebroventricularly with affinity-purified human anti-ribosomal P antibodies or IgG as control. Pharmacologic and immunologic treatments included the antidepressant drug fluoxetine, the antipsychotic drug haloperidol, and antiidiotypic antibodies. Behavior was assessed by the forced swimming test, motor deficits by rotarod, grip strength, and staircase tests, and cognitive deficits by T-maze alternation and passive avoidance tests.

RESULTS

Anti-ribosomal P antibodies induced depression-like behavior in the mice (mean +/- SEM 147.3 +/- 19.2 seconds of immobility versus 75.2 +/- 12.1 seconds of immobility in IgG-injected control mice; P < 0.005). The anti-ribosomal P antibody-induced depression-like behavior was partially blocked by a specific antiidiotypic antibody and significantly blocked by long-term treatment with fluoxetine, but not by short- or long-term treatment with haloperidol. The depressive behavior was not associated with any motor or cognitive deficits. Anti-ribosomal P antibodies specifically stained neurons in the hippocampus, cingulate cortex, and the primary olfactory piriform cortex, compatible with the previously described binding to the membrane-bound P0 ribosomal protein.

CONCLUSION

This is the first report of an experimental depression induced by a specific autoantibody. The results implicate olfactory and limbic areas in the pathogenesis of depression in general, and in central nervous system dysfunction in SLE in particular.

Anti-triosephosphate isomerase antibodies in cerebrospinal fluid are associated with neuropsychiatric lupus

We detected anti-triosephosphate isomerase antibodies (anti-TPI) in cerebrospinal fluid (CSF) in 5 of 12 neuropsychiatric lupus patients (41.6%) by Western blotting. C3d index was significantly higher in anti-TPI-positive patient (n=5, median 0.446) than in anti-TPI-negative patient (n=7, median 0.098) (p=0.019) CSF samples. TPI was detected from immune complexes (IC) isolated from CSF in 2 of 2 anti-TPI-positive patients tested and was not detected from IC in 5 of 5 anti-TPI-negative patients tested. Our results suggest that anti-TPI form IC in CSF and contribute to the pathogenesis of neuropsychiatric lupus by activating the complement system.

Relationship between serum NR2a antibodies and cognitive dysfunction in systemic lupus erythematosus

OBJECTIVE

To assess the association between serum NR2a antibodies and cognitive dysfunction in systemic lupus erythematosus (SLE).

METHODS

The study population consisted of English-speaking adults who met American College of Rheumatology (ACR) criteria for SLE and had at least 1 serum sample stored in the Hospital for Special Surgery Autoimmune Registry and Repository. Demographic and clinical information was obtained, and patients completed the neuropsychological test battery recommended by the ACR, the Center for Epidemiologic Studies Depression Scale, and the Spielberger State-Trait Anxiety Inventory. Cognitive impairment was defined as scores >1.5 SD below the mean of age-matched published normative data on at least 2 neuropsychological tests. Sera were tested for NR2a antibodies by enzyme-linked immunosorbent assay. Performance on neuropsychological tests was compared between NR2a-positive and NR2a-negative patients.

RESULTS

Of the 93 patients, 24 (25.8%) were positive for NR2a antibodies. Of the 48 patients who were cognitively impaired based on test results, 31% were positive for NR2a antibodies, compared with 20% of those who were not cognitively impaired (P = 0.24). Among antibody-positive patients, the mean +/- SD number of neuropsychological tests with abnormal results was 2.3 +/- 2.2, compared with 2.0 +/- 1.8 in the antibody-negative group (P = 0.59). Similar nonsignificant differences were found when impairment was defined using a more stringent definition (i.e., test scores >2.0 SD below the mean) and using a neuropsychologist's clinical ratings. No association was detected between NR2a antibody positivity and depressive symptoms (P = 0.73) or anxiety (P = 0.42).

CONCLUSION

No significant association was found between NR2a antibody positivity and cognitive dysfunction, depressive symptoms, or anxiety. These results indicate that the presence of these antibodies alone does not have a direct effect on cognitive functioning or any other neuropsychiatric manifestation of SLE.

International multicenter evaluation of autoantibodies to ribosomal P proteins

Autoantibodies to the ribosomal phosphoproteins (Rib-P) are a serological feature of patients with systemic lupus erythematosus (SLE). The reported prevalence of anti-Rib-P antibodies in SLE ranges from 10 to 40%, being higher in Asian patients. The variation in the observed frequency may be related to a number of factors but is dependent in large part on the test system used to detect the autoantibodies. An association of anti-Rib-P with central nervous system involvement and neuropsychiatric manifestations of SLE has been controversial. In the present international multicenter study, we evaluated the clinical accuracy of a new sensitive Rib-P-specific enzyme-linked immunosorbent assay based on recombinant Rib-P polypeptides. The results showed that 21.3% of 947 SLE patients, but only 0.7% of 1,113 control patients, had a positive test result (P < 0.0001). The sensitivity, specificity, positive and negative predictive values, and diagnostic efficiency were determined to be 21.3%, 99.3%, 95.6%, 62.2%, and 65.3%, respectively. When evaluated in the context of participating centers, the prevalence of anti-Rib-P antibodies was found in descending frequency, as follows: China (35%) > Poland (34%) > Japan (28%) > United States (26%) > Germany (Freiburg; 23.3%) > Denmark (20.5%) > Germany (Berlin; 19%) > Mexico (15.7%) > Israel (11.7%) > Brazil (10%) > Canada (8%). The substantial data from this study indicate that the prevalence of anti-Rib-P antibodies may not be restricted to the genetic background of the patients or to the detection system but may depend on regional practice differences and patient selection. We confirm previously reported associations of antiribosomal antibodies with clinical symptoms and serological findings. Remarkably, we found a lower occurrence of serositis in Rib-P-positive lupus patients.

Pathogenic autoantibodies: emerging insights into tissue injury

Accumulating evidence is emerging that B lymphocytes and autoantibodies are critical in the development of autoimmune disease. Even in certain disorders initially thought to be T cell-mediated, these immune components are now considered key players in the disease pathogenesis, and new autoantibody specificities have been added to the growing list of targets including cell surface receptors and ion channels that may be involved in a variety of neuropsychiatric and cardiovascular disorders. Studies of autoantibodies penetrating living cells suggest a dosage effect in generating a biological outcome in vivo. Some autoantibodies, such as those directed to double-stranded DNA, can bind to a variety of surrogate antigens located in different cellular compartments, and this may have different biological consequences. This polyreactive behavior could be related to their conformational diversity, or to the fact that the epitope recognized is distributed among other macromolecular antigens. In addition, recent studies revealed unsuspected mechanisms of pathogenesis, wherein autoantibodies have been described that can activate neuronal, endothelial cells or B lymphocytes. Other autoantibodies inactivate the target antigens, or exhibit a catalytic activity, releasing toxic oxygen products that may be linked to arthritic or atherosclerotic injury.

Major immunoreactive domains of human ribosomal P proteins lie N-terminal to a homologous C-22 sequence: application to a novel ELISA for systemic lupus erythematosus

The aim of this study was to identify immunoreactive domains on human ribosomal P0, P1 and P2 proteins, other than the C-22 peptide, to develop a novel ELISA using a combination of these proteins and to compare this ELISA with one using the C-22 peptide. Human recombinant P0, P1, P2 and mutant P0 lacking the homologous C-22 peptide (N-P0) were produced in bacteria and tested by ELISA and immunoblotting using sera from 48 patients with systemic lupus erythematosus (SLE), 48 with an unrelated inflammatory disorder (Crohn's disease) and 47 healthy controls. ELISA with P0, P1 and P2, premixed at equimolar concentrations, gave higher OD readings than each protein tested individually. Eighteen SLE sera tested positive by ELISA with premixed P0, P1, P2 but only 3 tested positive with the C-22 peptide. Twenty-two SLE sera reacted positively, as determined by immunoblotting, with 5 different P protein combinations: P1P2, P0P1P2, P1, P0P1, P0 and P1. Only sera reactive with all three P proteins reacted with the C-22 peptide, with absent or minimal reactivity with N-P0. Native antigens yielded sensitivity (6/48, 13%) similar to the C-22 peptide assay. An ELISA with premixed P1 and P2 gave higher OD values than the arithmetic means with P1 or P2. Fifteen SLE patients had antibodies to double stranded (ds)-DNA, of which 6 also had antibodies to P0P1P2 by ELISA but 12 reactive with P0P1P2 did not have discernable ds-DNA antibodies. Ribosomal P autoantibodies react mainly with epitopes N-terminal to a homologous C-22 peptide. An ELISA with premixed P0, P1 and P2 has 5-fold greater sensitivity (38%) for SLE than an assay with the conventional C-22 peptide (7%). The combined sensitivity for SLE for antibodies to P0P1P2 and ds-DNA is 56%, higher than C-22 and ds-DNA, 38%. Only one of the SLE patients had neuropsychiatric lupus.

Evaluation of a Novel Line-Blot Immunoassay for the Detection of Antibodies to Extractable Nuclear Antigens

We have evaluated the performance of a novel line-blot immunoassay (LIA; Mikrogen) and compared results with those obtained by CIE (in-house), ELISA (Pharmacia Diagnostics), and FEIA (Pharmacia Diagnostics). Sera from systemic lupus erythematosus (SLE) patients (n = 123), systemic sclerosis patients (n = 25), and healthy controls (n = 40) were analyzed for the presence of antibodies to RNP, Sm, SSA, SSB, CENP-B, Scl-70, and Jo-1. Reading of LIA results, as compared with a cutoff control, was performed by automatic analysis of the test strips. Because LIA enables recognition of separate subunits of RNP (68, A, and C), Sm (B and D), and SSA (52 and 60), at least two of the RNP antigens and either one of the Sm or SSA antigens should be detected for considering the test RNP, Sm, or SSA-positive, respectively. LIA had the highest sensitivity in patients with autoimmune connective tissue diseases: 131 specificities (not PO, PCNA, or histones), as compared with ELISA (121), FEIA (119), and CIE (80). However, LIA revealed three positive reactions in healthy controls; other assays were completely negative. LIA is better than CIE, but similar to ELISA and FEIA, in terms of detecting systemic sclerosis-associated antibodies (CENP-B and Scl-70). Furthermore, LIA had the highest sensitivity (17.9%) for the SLE-specific anti-Sm antibodies, as compared with ELISA (11.4%), CIE (8.1%), and FEIA (5.7%). Finally, anti-SSA antibodies were far more prevalent by LIA in the systemic sclerosis samples because of anti-SSA52 reactivity. The clinical relevance of the latter finding remains to be determined. In conclusion, LIA is suitable for routine evaluation of autoantibodies to extractable nuclear antigens.

Autoantibodies to a NR2A peptide of the glutamate/NMDA receptor in sera of patients with systemic lupus erythematosus

OBJECTIVE

To determine the prevalence of autoantibodies directed against an epitope of the glutamate/N-methyl-D-aspartic acid (NMDA) receptor subunit NR2A (which is highly expressed in human brain) in the sera of lupus patients, and to investigate the possible correlation of these antibodies with clinical and serological manifestations of systemic lupus erythematosus (SLE).

METHODS

Sera were obtained from 109 consecutive SLE patients. Controls were 65 patients with myasthenia gravis, 19 with autoimmune polyendocrine syndrome type I (APS I), and 65 healthy donors. A 15 amino acid long peptide based on a sequence within the NR2A subunit of the NMDA/glutamate receptor was synthesised. Antibodies to this peptide were determined by enzyme linked immunosorbent assay. Antibodies against double stranded DNA (dsDNA) were measured by Chrithidia luciliae assay. Disease activity was determined using the SLE disease activity index (SLEDAI).

RESULTS

Sera of 34/109 SLE patients (31%) reacted specifically with the NR2A peptide compared with only 4/65 myasthenia gravis patients (6.1%, p<0.001), 1/19 APS I patients (5.3%, p<0.02), and 3/65 healthy controls (4.6%, p<0.001). No correlation was found between the presence of NR2A and dsDNA or anti-cardiolipin specific autoantibodies. In addition, no significant correlation was observed between the presence of NR2A specific antibodies and the SLEDAI score or any lupus related clinical manifestations.

CONCLUSIONS

A significant number of SLE patients (31%) have NR2A specific antibodies that do not correlate with anti-dsDNA antibodies. Additional studies of lupus patients with neurological disorders should elucidate the role of NR2A specific antibodies in lupus related CNS manifestations.

Predictors of neuropsychiatric damage in systemic lupus erythematosus: data from the Maryland lupus cohort

OBJECTIVE

To identify factors predictive of significant neuropsychiatric (NP) damage in systemic lupus erythematosus (SLE).

METHODS

One hundred and thirty patients with SLE were followed at the University of Maryland Lupus Clinic from 1992 until 2003. NP manifestations were defined according to the revised American College of Rheumatology (ACR) nomenclature and case definitions for NP-SLE syndromes. Disease activity was measured using the SLE Disease Activity Index (SLEDAI), organ damage using the Systemic Lupus International Collaborating Clinics Damage Index SLICC/ACR (SDI); NP damage (NPDI) was measured with the corresponding domain of the SDI. At end of study period, 64 patients exhibited no NP damage (NPDI = 0) and 66 patients developed significant NP damage (defined as NPDI > or =1). The baseline features for these two patient groups were compared, and variables found to be significantly different were examined by multivariable analyses to determine their contribution to NP damage.

RESULTS

Significant NP damage is common in SLE; mortality is infrequent and the cause of death is unrelated to NP damage. Independent predictors of significant NP damage were disease activity, Caucasian ethnicity and the presence of antiphospholipid antibodies and anti-Ro/SSA antibody. Certain clinical features at baseline predicted specific NP damage. For example, higher disease activity at baseline was predictive of psychosis and cognitive impairment, anti-dsDNA was predictive of polyneuropathy, and antiphospholipid antibodies were predictive of seizures and cerebrovascular accidents.

CONCLUSIONS

In this longitudinal SLE cohort, significant cumulative NP damage occurred. Early aggressive therapy targeted towards NP manifestations may prevent the occurrence of NP damage.

Pathogenic roles of B cells in human autoimmunity; insights from the clinic

The pathogenic roles of B cells in human autoimmune diseases involve a multitude of mechanistic pathways and include the well-established contributions of autoantibodies and immune complexes that induce local inflammatory reactions and tissue destruction. Recent results using several novel B cell-directed therapies have provided new insights into additional roles of B cells in human autoimmunity. In this review, we will highlight some of these studies and discuss how clinical insights parallel murine models of normal immunity and autoimmunity.