Antiribosomal P antibodies in pediatric patients with systemic lupus erythematosus and psychosis

Biomarkers Associated with Organ-Specific Involvement in Juvenile Systemic Lupus Erythematosus

Juvenile systemic lupus erythematosus (JSLE) is characterised by onset before 18 years of age and more severe disease phenotype, increased morbidity and mortality compared to adult-onset SLE. Management strategies in JSLE rely heavily on evidence derived from adult-onset SLE studies; therefore, identifying biomarkers associated with the disease pathogenesis and reflecting particularities of JSLE clinical phenotype holds promise for better patient management and improved outcomes. This narrative review summarises the evidence related to various traditional and novel biomarkers that have shown a promising role in identifying and predicting specific organ involvement in JSLE and appraises the evidence regarding their clinical utility, focusing in particular on renal biomarkers, while also emphasising the research into cardiovascular, haematological, neurological, skin and joint disease-related JSLE biomarkers, as well as genetic biomarkers with potential clinical applications.

Immune Response to Enterococcus gallinarum in Lupus Patients Is Associated With a Subset of Lupus-Associated Autoantibodies

Interactions between gut microbes and the immune system influence autoimmune disorders like systemic lupus erythematosus (SLE). Recently, Enterococcus gallinarum, a gram-positive commensal gut bacterium, was implicated as a candidate pathobiont in SLE. The present study was undertaken to evaluate the influence of E. gallinarum exposure on clinical parameters of SLE. Since circulating IgG antibodies to whole bacteria have been established as a surrogate marker for bacterial exposure, anti-E. gallinarum IgG antibodies were measured in banked serum samples from SLE patients and healthy controls in the Oklahoma Cohort for Rheumatic Diseases. The associations between anti-E. gallinarum antibody titers and clinical indicators of lupus were studied. Antibodies to human RNA were studied in a subset of patients. Our results show that sera from both patients and healthy controls had IgG and IgA antibodies reactive with E. gallinarum. The antibody titers between the two groups were not different. However, SLE patients with Ribosomal P autoantibodies had higher anti-E. gallinarum IgG titers compared to healthy controls. In addition to anti-Ribosomal P, higher anti-E. gallinarum titers were also significantly associated with the presence of anti-dsDNA and anti-Sm autoantibodies. In the subset of patients with anti-Ribosomal P and anti-dsDNA, the anti-E. gallinarum titers correlated significantly with antibodies to human RNA. Our data show that both healthy individuals and SLE patients were sero-reactive to E. gallinarum. In SLE patients, the immune response to E. gallinarum was associated with antibody response to a specific subset of lupus autoantigens. These findings provide additional evidence that E. gallinarum may be a pathobiont for SLE in susceptible individuals.

Neuroprotective effect of microglia against impairments of auditory steady-state response induced by anti-P IgG from SLE patients in naïve mice

OBJECTIVE

Autoantibodies against ribosomal P proteins (anti-P antibodies) are strongly associated with the neuropsychiatric manifestations of systemic lupus erythematosus (NPSLE). The present study was designed to assess whether anti-P antibodies can induce abnormal brain electrical activities in mice and investigate the potential cytopathological mechanism.

METHODS

Affinity-purified human anti-ribosomal P antibodies were injected intravenously into mice after blood-brain barrier (BBB) disruption. The auditory steady-state response (ASSR) was evaluated based on electroencephalography (EEG) signals in response to 40-Hz click-train stimuli, which were recorded from electrodes implanted in the skull of mice. Immunofluorescence staining was used to examine the morphology and density of neurons and glia in the hippocampus and cortex. The presence of apoptosis in the brain tissues was studied using the TUNEL assay. A PLX3397 diet was used to selectively eliminate microglia from the brains of mice.

RESULTS

Circulating anti-P antibodies caused an enhancement of the ASSR and the activation of microglia through the disrupted BBB, while no obvious neural apoptosis was observed. In contrast, when microglia were depleted, anti-P antibodies induced a serious reduction in the ASSR and neural apoptosis.

CONCLUSION

Our study indicates that anti-P antibodies can directly induce the dysfunction of auditory-evoked potentials in the brain and that microglia are involved in the protection of neural activity after the invasion of anti-P antibodies, which could have important implications for NPSLE.

A review and meta-analysis of anti-ribosomal P autoantibodies in systemic lupus erythematosus

The discovery of autoantibodies to ribosomal proteins (anti-RibP) dates back more than fifty years when antibodies to ribosomes were identified in systemic lupus erythematosus (SLE) sera. Over the years, anti-RibP autoantibodies have been the subject of extensive study and became known as a highly specific biomarker for the diagnosis of SLE and were associated with neuropsychiatric SLE (NPSLE), lupus nephritis (LN) and hepatitis (LH). As demonstrated by studies on cultured human cells and of murine models, there is evidence to suggest that anti-RibP may have a pathogenic role in LN and NPSLE. Despite a wealth of evidence, in comparison to other SLE autoantibodies such as anti-Sm and anti-dsDNA, anti-RibP has not been included in classification criteria for SLE. A significant challenge is the variability of assays used to detect anti-RibP, including the antigens and diagnostic platforms employed. This may account for the marked variation in frequencies (10-47%) in SLE and its association with clinical and demographic features reported in SLE cohorts. We performed a systematic literature review and meta-analysis to help clarify its prevalence, various clinical and serological associations in SLE based on the different RibP antigens and assay platforms used.

Anti-ribosomal P antibody: a multicenter study in childhood-onset systemic lupus erythematosus patients

Objectives Anti-ribosomal P protein (anti-P) autoantibodies are highly specific for systemic lupus erythematosus (SLE). However, the evaluation of this autoantibody in childhood-onset SLE (cSLE) populations has been limited to a few small series, hampering the interpretation of the clinical and laboratorial associations. Therefore, the objective of this multicenter cohort study was to evaluate demographic, clinical/laboratorial features, and disease damage score in cSLE patients with and without the presence of anti-P antibody. Methods This was a retrospective multicenter study performed in 10 pediatric rheumatology services of São Paulo state, Brazil. Anti-P antibodies were measured by ELISA in 228 cSLE patients. Results Anti-P antibodies were observed in 61/228 (27%) cSLE patients. Frequencies of cumulative lymphadenopathy (29% vs. 15%, p = 0.014), acute confusional state (13% vs. 5%, p = 0.041), mood disorder (18% vs. 8%, p = 0.041), autoimmune hemolytic anemia (34% vs. 15%, p = 0.001), as well as presence of anti-Sm (67% vs. 40%, p = 0.001), anti-RNP (39% vs. 21%, p = 0.012) and anti-Ro/SSA antibodies (43% vs. 25%, p = 0.016) were significantly higher in cSLE patients with anti-P antibodies compared to those without these autoantibodies. A multiple regression model revealed that anti-P antibodies were associated with autoimmune hemolytic anemia (odds ratio (OR) = 2.758, 95% confidence interval (CI): 1.304-5.833, p = 0.008) and anti-Sm antibody (OR = 2.719, 95% CI: 1.365-5.418, p = 0.004). The SLICC/ACR damage index was comparable in patients with and without anti-P antibodies ( p = 0.780). Conclusions The novel association of anti-P antibodies and autoimmune hemolytic anemia was evidenced in cSLE patients and further studies are necessary to determine if anti-P titers may vary with this hematological manifestation.

European evidence-based recommendations for diagnosis and treatment of childhood-onset systemic lupus erythematosus: the SHARE initiative

Childhood-onset systemic lupus erythematosus (cSLE) is a rare, multisystem and potentially life-threatening autoimmune disorder with significant associated morbidity. Evidence-based guidelines are sparse and management is often based on clinical expertise. SHARE (Single Hub and Access point for paediatric Rheumatology in Europe) was launched to optimise and disseminate management regimens for children and young adults with rheumatic diseases like cSLE. Here, we provide evidence-based recommendations for diagnosis and treatment of cSLE. In view of extent and complexity of cSLE and its various manifestations, recommendations for lupus nephritis and antiphospholipid syndrome will be published separately. Recommendations were generated using the EULAR (European League Against Rheumatism) standard operating procedure. An expert committee consisting of paediatric rheumatologists and representation of paediatric nephrology from across Europe discussed evidence-based recommendations during two consensus meetings. Recommendations were accepted if >80% agreement was reached. A total of 25 recommendations regarding key approaches to diagnosis and treatment of cSLE were made. The recommendations include 11 on diagnosis, 9 on disease monitoring and 5 on general treatment. Topics included: appropriate use of SLE classification criteria, disease activity and damage indices; adequate assessment of autoantibody profiles; secondary macrophage activation syndrome; use of hydroxychloroquine and corticosteroid-sparing regimens; and the importance of addressing poor adherence. Ten recommendations were accepted regarding general diagnostic strategies and treatment indications of neuropsychiatric cSLE. The SHARE recommendations for cSLE and neuropsychiatric manifestations of cSLE have been formulated by an evidence-based consensus process to support uniform, high-quality standards of care for children with cSLE.

Ribosomal P antibody: 30 years on the road

The identity of the protein antigens targeted by anti-cytoplasmic antibodies in lupus was discovered 30 years ago. These antigens are three acidic ribosomal phosphoproteins, P0, P1, and P2. Precise identification of the shared epitope on these three proteins enabled sensitive and specific immunoassays to be developed. Anti-P antibodies are highly specific for systemic lupus erythematosus (SLE) and occur in 15%–35% of patients, depending on ethnicity as well as the age of onset. Increased frequencies of detection of anti-P have been reported in childhood SLE as well as in neuropsychiatric, renal, and hepatic disease. While longitudinal studies by the Systemic Lupus International Collaborating Clinics (SLICC) consortium supported the association of anti-P with neuropsychiatric lupus, the predictive value of antibody determination remains controversial. This is likely explained by the heterogeneity of neuropsychiatric lupus as well as by the different methodologies used for assay. A number of experimental studies have suggested a direct pathogenic role for anti-P antibodies in brain disease. Findings include cross reactivity between anti-P and a neuronal surface antigen, which was detected in areas of the brain involved in memory, cognition, and emotion. Direct injection of anti-P antibodies into the brains of rodents was also associated with abnormal electrical activity and behavioral disturbances. Taken together, research over the last 30 years has established anti-P antibodies as a useful diagnostic marker of SLE and at least a subset of patients with neuropsychiatric disease. Further research is required to fine tune the association of anti-P with clinical manifestations and establish beyond high probability a pathophysiologic role for the antibodies.

The diagnosis and clinical management of the neuropsychiatric manifestations of lupus

Neuropsychiatric (NP) involvement in Systemic Lupus Erythematosus (SLE), can be a severe and troubling manifestation of the disease that heavily impacts patient's health, quality of life and disease outcome. It is one of the most complex expressions of SLE which can affect central, peripheral and autonomous nervous system. Complex interrelated pathogenetic mechanisms, including genetic factors, vasculopathy, vascular occlusion, neuroendocrine-immune imbalance, tissue and neuronal damage mediated by autoantibodies, inflammatory mediators, blood brain barrier dysfunction and direct neuronal cell death can be all involved. About NPSLE a number of issues are still matter of debate: from classification and burden of NPSLE to attribution and diagnosis. The role of neuroimaging and new methods of investigation still remain pivotal and rapidly evolving as well as is the increasing knowledge in the pathogenesis. Overall, two main pathogenetic pathways have been recognized yielding different clinical phenotypes: a predominant ischemic-vascular one involving large and small blood vessels, mediated by aPL, immune complexes and leuko-agglutination which it is manifested with more frequent focal NP clinical pictures and a predominantly inflammatory-neurotoxic one mediated by complement activation, increased permeability of the BBB, intrathecal migration of autoantibodies, local production of immune complexes and pro-inflammatory cytokines and other inflammatory mediators usually appearing as diffuse NP manifestations. In the attempt to depict a journey throughout NPSLE from diagnosis to a reasoned therapeutic approach, classification, epidemiology, attribution, risk factors, diagnostic challenges, neuroimaging techniques and pathogenesis will be considered in this narrative review based on the most relevant and recent published data.

Anti-ribosomal P-protein and its role in psychiatric manifestations of systemic lupus erythematosus: myth or reality?

Systemic lupus erythematosus (SLE) is an autoimmune disease that may involve the central nervous system (CNS) resulting in neuropsychiatric manifestations. The associated psychiatric disorders include depression, psychosis, mood disorders, anxiety, cognitive dysfunction, and delirium/encephalopathy. Several autoantibodies may play a role in the pathogenesis of psychiatric complications of SLE, particularly antibodies against ribosomal P-proteins (anti-P) and possibly antibodies against endothelial cells (AECA). The reported prevalence of anti-P is highly variable in SLE patients and is dependent on different ethnic backgrounds, sensitivity and specificity of the assays employed for autoantibody detection, and the time at which sera were analysed in relation to the clinical event. Controversial data exist on the association of anti-P with psychiatric manifestations of SLE. These autoantibodies have been suggested to be specific markers of the psychiatric manifestations of SLE, particularly of the psychosis and depression, and the antibody level varied with the clinical activity of the disease. Some studies have confirmed the hypothesis of an association of anti-P antibodies with psychiatric manifestations of neuropsychiatric SLE (NPSLE) while others have disputed this relationship. This review summarizes the recent studies about relationship between anti-P antibodies and psychiatric manifestation of SLE.

Review: Neuropsychiatric involvement in pediatric systemic lupus erythematosus

Neuropsychiatric (NP) manifestations are found in approximately 25% of children and adolescents with pediatric SLE (pSLE). In 70% of those, NP involvement will occur within the first year from the time of diagnosis. Headaches (66%), psychosis (36%), cognitive dysfunction (27%) and cerebrovascular disease (24%) are the most common presentations. The support of a psychiatrist is often required. Anti-phospholipid antibodies are associated with distinct NP disease entities and may be implicated in the pathogenesis of several manifestations of NP-pSLE including chorea, cerebrovascular disease and seizures. The role of novel auto-antibodies and imaging modalities is currently explored. The treatment of NP-pSLE is not based on prospective studies; however, an immunosuppressive combination therapy consisting of high doses of prednisone and a second line agent such as cyclophosphamide or azathioprine is commonly suggested for children with NP-pSLE. The role of novel therapies is currently studied. The outcome of children with NP-pSLE is relatively good. The overall survival is 95—97%, 20% of children experience a disease flare during childhood and 25% have evidence of permanent neuropsychiatric damage. Lupus (2007) 16, 564—571.

Biomarkers for CNS involvement in pediatric lupus

CNS disease, or central neuropsychiatric lupus erythematosus (cNPSLE), occurs frequently in pediatric lupus, leading to significant morbidity and poor long-term outcomes. Diagnosing cNPSLE is especially difficult in pediatrics; many current diagnostic tools are invasive and/or costly, and there are no current accepted screening mechanisms. The most complicated aspect of diagnosis is differentiating primary disease from other etiologies; research to discover new biomarkers is attempting to address this dilemma. With many mechanisms involved in the pathogenesis of cNPSLE, biomarker profiles across several modalities (molecular, psychometric and neuroimaging) will need to be used. For the care of children with lupus, the challenge will be to develop biomarkers that are accessible by noninvasive measures and reliable in a pediatric population.

Meta-analysis of anti-ribosomal P antibodies in lupus psychosis

AIM: To perform a meta-analysis of the prevalence of anti-ribosomal P (aRP) antibodies in lupus psychosis, and the odds of psychosis in aRP-positive subjects.

METHODS: We identified articles by searching PubMed, PsychInfo, and ISI, and the reference lists of identified studies.

RESULTS: Twenty-four studies met the inclusion criteria. Positive aRP antibodies were found in 51% (91 of 179 total cases) of cases of lupus psychosis. There was an almost 3.5-fold increased odds of psychosis in aRP-positive patients (OR = 3.46, 95%CI: 1.97-6.09, P < 0.001). The population attributable risk percentage was 36% for aRP antibodies.

CONCLUSION: aRP antibodies are common in lupus psychosis, although the potential mechanism(s) underlying this association remain unclear. Given the overlap between the clinical presentation and risk factors for lupus psychosis and schizophrenia, further investigation of aRP antibodies in schizophrenia is warranted.

Prevalence and clinical significance of anti-ribosomal P antibody in childhood-onset systemic lupus erythematosus

Objective: To investigate the prevalence of the anti-ribosomal P (anti-P) antibodies in childhood-onset systemic lupus erythematosus patients (cSLE), healthy controls and first degree relatives. To elucidate the association between anti-P and disease activity, laboratory and treatment features in cSLE patients. Methods: We included consecutive SLE patients with disease onset before 16 years. Controls were age- and sex-matched. SLE patients were assessed for clinical and laboratory SLE manifestations, disease activity (SLE Disease Activity Index (SLEDAI)), damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI)) and current drug exposures. Mood disorders were determined through Becks Depression and Becks Anxiety Inventory. Anti-P measured by enzyme-linked immunosorbent assay. Results: We included 50 consecutive cSLE patients (mean age of 16.82 ± 3.46 years), 35 first degree relatives (mean age of 38.73 ± 3.89 years) and 20 health control (mean age of 18.3 ± 4.97 years). Anti-P was observed in 13 (26%) cSLE patients and in no first-degree relative ( p < 0.01) or control ( p < 0.01). Anti-P was more frequently observed in patients with anxiety ( p < 0.002). No other clinical, laboratory or treatment features, including SLEDAI and SDI scores were associated with the presence of anti-P in cSLE patients. Conclusion: Anti-P is frequently observed in cSLE patients and was associated with the presence of anxiety in this cohort of cSLE.

Autoantibodies as biomarkers for the prediction of neuropsychiatric events in systemic lupus erythematosus

OBJECTIVE

Neuropsychiatric events occur unpredictably in systemic lupus erythematosus (SLE) and most biomarker associations remain to be prospectively validated. This study examined a disease inception cohort of 1047 SLE patients to determine which autoantibodies at enrolment predicted subsequent neuropsychiatric events.

METHODS

Patients with a recent SLE diagnosis were assessed prospectively for up to 10 years for neuropsychiatric events using the American College of Rheumatology case definitions. Decision rules of graded stringency determined whether neuropsychiatric events were attributable to SLE. Associations between the first neuropsychiatric event and baseline autoantibodies (lupus anticoagulant (LA), anticardiolipin, anti-β(2) glycoprotein-I, anti-ribosomal P and anti-NR2 glutamate receptor) were tested by Cox proportional hazards regression.

RESULTS

Disease duration at enrolment was 5.4 ± 4.2 months, follow-up was 3.6 ± 2.6 years. Patients were 89.1% female with mean (±SD) age 35.2 ± 13.7 years. 495/1047 (47.3%) developed one or more neuropsychiatric event (total 917 events). Neuropsychiatric events attributed to SLE were 15.4% (model A) and 28.2% (model B). At enrolment 21.9% of patients had LA, 13.4% anticardiolipin, 15.1% anti-β(2) glycoprotein-I, 9.2% anti-ribosomal P and 13.7% anti-NR2 antibodies. LA at baseline was associated with subsequent intracranial thrombosis (total n=22) attributed to SLE (model B) (HR 2.54, 95% CI 1.08 to 5.94). Anti-ribosomal P antibody was associated with subsequent psychosis (total n=14) attributed to SLE (model B) (HR 3.92, 95% CI 1.23 to 12.5, p=0.02). Other autoantibodies did not predict neuropsychiatric events.

CONCLUSION

In a prospective study of 1047 recently diagnosed SLE patients, LA and anti-ribosomal P antibodies are associated with an increased future risk of intracranial thrombosis and lupus psychosis, respectively.

Autologous hematopoietic stem cell transplantation for childhood autoimmune disease

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) can be used in the management of patients with autoimmune disorders. Experience gained in adults has helped to better define the conditioning regimens required and appropriate selection of patients who are most likely to benefit from autologous HSCT. The field has been shifting toward the use of safer and less intense nonmyeloablative regimens used earlier in the disease course before patients accumulate extensive irreversible organ damage. This article reviews the experience of using autologous HSCT in treating the most common childhood autoimmune and rheumatic diseases, primarily juvenile idiopathic arthritis, systemic lupus erythematosus, and diabetes mellitus.

Clinical perspectives on autoimmune processes in schizophrenia

This article reviews the epidemiology of autoimmune conditions in schizophrenia, symptom manifestations of autoimmune conditions resembling schizophrenia, and the immunological changes observed in schizophrenia; and reflects on their associations with neurodevelopment, neurodegeneration, clinical course, and management of schizophrenia.

Pathogenesis of neuropsychiatric systemic lupus erythematosus and potential biomarkers

Systemic lupus erythematosus is a chronic, multisystemic, autoimmune disease that may involve the central, peripheral, and autonomic nervous systems and can present with a wide variety of neurological and psychiatric manifestations. In this article, we review the recent literature pertaining to the pathogenesis of neuropsychiatric systemic lupus erythematosus (NPSLE). We searched the PUBMED database with no chronological constraints using the following terms: "neuropsychiatric systemic lupus erythematosus" cross-referenced with the terms "pathogenesis" and "biomarkers" for full-text articles in English. The etiology of NPSLE is as yet unknown, though numerous autoantibodies and cytokines have been suggested as possible mediators. Of the numerous autoantibodies and biomarkers examined, anti-phospholipid, anti-ribosomal P, anti-neuronal, anti-glial fibrillary acidic protein (GFAP), anti-endothelial cell, anti-N-methyl-D: -aspartate (NMDA), microtubule-associated protein 2 (MAP-2), and matrix metalloproteinase-9 (MMP-9) appear to be elevated in patients with NPSLE. Cytokines that may be involved in the pathology of NPSLE include interleukin (IL)-2, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-alpha, and interferons (IFN)-alpha and -gamma. With continued advances in immunological research, new insights into the pathophysiologic mechanisms of NPSLE may lead to the development of biomarkers and new treatment strategies.

Laboratory tests in the diagnosis and follow-up of pediatric rheumatic diseases: an update

OBJECTIVES

We reviewed the literature to evaluate the role of common laboratory tests and to examine the recent progress in the laboratory diagnosis of pediatric rheumatic diseases.

METHODS

We used the PubMed database (1950-2008) to search for the keywords "laboratory," "erythrocyte sedimentation rate" (ESR), "C-reactive protein" (CRP), "blood cytology," "procalcitonin" (PCT), "complement system," "ferritin," "antistreptolysin O titer" (ASO), "autoantibodies," "genetic studies," in conjunction with "rheumatic disease in children" and "pediatric autoimmune diseases." All relevant original and review articles in English were reviewed as well as textbooks of pediatric rheumatology.

RESULTS

Laboratory tests (ESR, CRP, blood cytology, complement system, ferritin, ASO titer) play an important role in confirming a diagnosis and in the follow-up of rheumatic diseases in the pediatric age group. The ESR is probably the most widely measured index of the acute phase response. Measurement of CRP is very useful in the rapid diagnosis of infection as a progressive increase can be shown in the first 48 hours. Also, the subsequent fall in serum CRP concentration on resolution of inflammation is useful for monitoring the efficacy of treatment. In chronic diseases, a combination of CRP and ESR may provide the most useful information. Cytopenia and different forms of anemia can be encountered in many rheumatic diseases: they can be related to disease activity or to therapeutic side effects. Determination of complement levels (C3 and/or C4) is useful in the follow-up of systemic lupus erythematosus (SLE) and membranoproliferative glomerulonephritis. Ferritin is a laboratory hallmark of primary and secondary hemophagocytic lymphohistiocytosis. ASO titer should be obtained to confirm a diagnosis of acute rheumatic fever; other important antibody markers of streptococcal infection include antihyaluronidase, antideoxyribonuclease B, and antistreptokinase antibodies. We also found that, in the pediatric age, the main indication for synovial fluid analysis is suspected joint infection. Antinuclear antibodies, anti-Smith antigen, and anti-double-stranded DNA antibodies are important in the diagnosis of SLE, are useful prognostic markers, and facilitate clinical and treatment follow-up. Anti-SSA/Ro and anti-SSB/La antibodies are associated with Sjögren's syndrome and congenital heart block, while the anti-U1 small nuclear ribonucleoprotein antibodies show high specificity for mixed connective tissue disease. Repetitive spontaneous abortions, thrombocytopenia, and many types of venous or arterial thrombosis are associated with antiphospholipid antibodies. The presence of cytoplasmic antineutrophil antibodies is essential in the diagnosis of Wegener granulomatosis. The discovery of underlying single causative gene defects led to the identification of several autoinflammatory diseases, a group of genetic disorders characterized by recurrent attacks of inflammation (hereditary periodic fever syndromes). These include familial Mediterranean fever due to mutations in the Mediterranean fever (MEFV) gene, hyperimmunoglobulinemia D syndrome due to mutations in the MK gene for mevalonate kinase, cryopyrinopathies such as Muckle-Wells syndrome or neonatal-onset multisystemic inflammatory disease (neonatal-onset multisystemic inflammatory disease or chronic infantile neurological cutaneous and articular (CINCA)) associated with cold-induced autoinflammatory syndrome 1 gene mutations, and tumor necrosis factor receptor-associated periodic syndrome due to mutation of TNF receptor I gene.

CONCLUSIONS

Laboratory investigations play an important role in the diagnosis and follow-up of inflammatory rheumatic diseases in children. A good history and a complete physical examination are the best screening tests. Routine laboratory tests are useful to confirm a suspected diagnosis, to assess disease activity, and to measure the response and toxicity to treatment. Only a few tests represent diagnostic criteria such as antinuclear antibodies and anti-double-stranded DNA in SLE or cytoplasmic antineutrophil cytoplasmic autoantibodies in Wegener's granulomatosis. Recent advances in molecular genetics have impacted diagnosis, pathogenesis, and treatment in genetic fever syndromes.

Autoantibodies in pediatric systemic lupus erythematosus: ethnic grouping, cluster analysis, and clinical correlations

OBJECTIVE

(1) To evaluate the spectrum of serum autoantibodies in pediatric-onset systemic lupus erythematosus (pSLE) with a focus on ethnic differences; (2) using cluster analysis, to identify patients with similar autoantibody patterns and to determine their clinical associations.

METHODS

A single-center cohort study of all patients with newly diagnosed pSLE seen over an 8-year period was performed. Ethnicity, clinical, and serological data were prospectively collected from 156/169 patients (92%). The frequencies of 10 selected autoantibodies among ethnic groups were compared. Cluster analysis identified groups of patients with similar autoantibody profiles. Associations of these groups with clinical and laboratory features of pSLE were examined.

RESULTS

Among our 5 ethnic groups, there were differences only in the prevalence of anti-U1RNP and anti-Sm antibodies, which occurred more frequently in non-Caucasian patients (p < 0.0001, p < 0.01, respectively). Cluster analysis revealed 3 autoantibody clusters. Cluster 1 consisted of anti-dsDNA antibodies. Cluster 2 consisted of anti-dsDNA, antichromatin, antiribosomal P, anti-U1RNP, anti-Sm, anti-Ro and anti-La autoantibody. Cluster 3 consisted of anti-dsDNA, anti-RNP, and anti-Sm autoantibody. The highest proportion of Caucasians was in cluster 1 (p < 0.05), which was characterized by a mild disease with infrequent major organ involvement compared to cluster 2, which had the highest frequency of nephritis, renal failure, serositis, and hemolytic anemia, or cluster 3, which was characterized by frequent neuropsychiatric disease and nephritis.

CONCLUSION

We observed ethnic differences in autoantibody profiles in pSLE. Autoantibodies tended to cluster together and these clusters were associated with different clinical courses.

Association of anti-ribosomal P protein antibodies with neuropsychiatric and other manifestations of systemic lupus erythematosus

The objective of our study was to determine the prevalence of neuropsychiatric manifestations and anti-ribosomal P antibodies (aRP) in SLE and to examine the diagnostic utility and associations of aRP with neuropsychiatric and other disease manifestations. Thirty two consecutive SLE patients, diagnosed according to the updated 1997 ACR criteria, were studied. A full medical history, rheumatological, neurological, psychiatric examination, and psychometric evaluation, including a battery of tests for cognitive dysfunction and the Symptom Checklist-90-Revised depression and anxiety scales were administered to all patients. Disease activity was scored using the SLEDAI. Neuropsychiatric manifestations were diagnosed and categorized according to the 1999 ACR case definitions for 19 NPSLE syndromes. Laboratory and serologic tests including ANA, anti-ds DNA, anti-cardiolipin antibodies (aCL) and aRP (ELISA) were also carried out. Twenty six (81.2%) patients had one or more NP manifestations. Depression (59.4%), headache (46.9%) and cognitive dysfunction (37.5%) were the commonest NPSLE syndromes. Other less commonly detected manifestations included seizures, anxiety, acute confusional state, stroke, and psychosis. aRP was positive in seven (21.9%) patients, all of whom had one or more NPSLE syndromes. Patients with psychiatric manifestations in general and mood disorders in particular had significantly higher mean titers of aRP than patients without these disorders (p < 0.05). aRP were found to be significantly associated with a younger age at the onset of SLE, with more severe articular manifestations and with the presence but not the severity of depression. aRP were highly specific for NPSLE and depression, and they were highly sensitive for psychosis. Neuropsychiatric manifestations are found in 81.2% of unselected Egyptian SLE patients. The presence of aRP antibodies positively predicts patients with psychiatric manifestations in general and mood disorders in particular, for which aRP is specific, but not sensitive. However, aRP is sensitive for psychosis, so that its absence in patients with SLE may help exclude Lupus psychosis.

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.

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.

The role of autoantibodies in pediatric neuropsychiatric systemic lupus erythematosus

Neuropsychiatric syndromes are prevalent in pediatric patients with systemic lupus erythematosus (SLE) and often manifest early in disease course and with significant associated morbidity. Postulated pathogenic mechanisms of peripheral and central nervous system events include vasculopathy, autoantibody effects and systemic inflammation. The pathogenic roles of anti-phospholipid, anti-ribosomal-P and anti-neuronal autoantibodies have been examined in both focal and diffuse adult neuropsychiatric syndromes. Few studies have probed associations between these autoantibodies and pediatric neuropsychiatric SLE (NP-SLE). Retrospective review of a large ethnically diverse pediatric SLE cohort revealed anti-phospholipid, anti-ribosomal P, and anti-neuronal antibodies to be more prevalent than in many adult studies. Rates of anti-phospholipid and anti-ribosomal P antibody positivity were similar to those of other pediatric reports. Association between anti-neuronal antibodies and NP-SLE events appeared statistically significant in this cohort. Prospective inception cohort studies will need to be undertaken to investigate the significance and utility of autoantibody testing in pediatric NP-SLE.

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.

Treatment of acute neuropsychiatric lupus with intravenous immunoglobulin (IVIG): a case report and review of the literature

Neuropsychiatric lupus can be difficult to diagnose, and little prospective data exists to help direct management. In this case report we describe the acute onset of symptoms of depression, mania, and psychosis and their complete resolution 48 h following a 5-day treatment course of intravenous immunoglobulin (IVIG) in a 20-year-old woman with systemic lupus erythematosus (SLE). We review the literature on IVIG for the management of neuropsychiatric lupus. We propose that when more toxic therapies are refused or symptoms do not remit with other treatments, IVIG should be considered in patients with neuropsychiatric lupus.

Accuracy of anti–ribosomal P protein antibody testing for the diagnosis of neuropsychiatric systemic lupus erythematosus: An international meta-analysis

OBJECTIVE

To quantitatively evaluate the diagnostic accuracy of antibodies to ribosomal P proteins (anti-P) for neuropsychiatric systemic lupus erythematosus (NPSLE) in general, for psychosis, mood disorder, or both, and for other diffuse manifestations.

METHODS

This international meta-analysis combined standardized data from 1,537 lupus patients contributed by 14 research teams. Weighted estimation of sensitivity and specificity with fixed-effects and random-effects models, as well as summary receiver operating characteristic (SROC) curve analysis, was used to summarize test performance. The robustness of the overall estimates was examined in sensitivity analyses that included additional studies published up to November 1, 2004 in the Medline, EMBase, and Cochrane databases.

RESULTS

Combining the data from the 14 teams, the weighted sensitivity and specificity estimates for the diagnosis of NPSLE were 26% (95% confidence interval [95% CI] 15-42%) and 80% (95% CI 74-85%), respectively. For psychosis, mood disorder, or both, the sensitivity and specificity were 27% (95% CI 14-47%) and 80% (95% CI 74-85%), respectively. For other diffuse manifestations, the sensitivity was 24% (95% CI 12-42%), and the specificity was 80% (95% CI 73-85%). The proportion of patients with anti-P antibodies did not vary markedly across different presentations of NPSLE. Between-study heterogeneity was substantial, but the SROC curves were consistent with the weighted estimates. In further analyses that included another 24 published studies, only the sensitivity for psychosis and/or mood disorder was slightly improved, but it was still suboptimal (42% [95% CI 30-53%]); the specificity remained essentially the same (81% [95% CI 76-85%]).

CONCLUSION

Anti-P antibody testing has limited diagnostic value for NPSLE, and it is not helpful in differentiating among various disease phenotypes.

European Consensus Lupus Activity Measurement is sensitive to change in disease activity in childhood-onset systemic lupus erythematosus

OBJECTIVES

To evaluate the European Consensus Lupus Activity Measurement (ECLAM) for responsiveness to change in disease activity when used in childhood-onset systemic lupus erythematosus (cSLE). To confirm the construct validity and to characterize the measurement properties of the ECLAM by assessing its ability to predict damage and steroid requirements.

METHODS

The disease courses of 66 newly diagnosed cSLE patients were reviewed. The ECLAM and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) were scored for all clinic visits and hospitalizations. Damage was assessed at the end of the followup period using the Systemic Lupus International Collaboration Clinics/American College of Rheumatology Damage Index. Disease activity at the time of diagnosis, 6 months after diagnosis, at the time of first flare, and 6 months after first flare was used to estimate responsiveness of the measures. Responsiveness was measured by the effect size, the effect size index, the standardized response mean, and the relative efficiency index (REI). The measurement properties of the ECLAM and SLEDAI over time were examined by comparing the ability of both measures to predict damage and oral steroid requirement.

RESULTS

The ECLAM and SLEDAI are both responsive to change in disease activity irrespective of the statistic used. The ECLAM is more sensitive than the SLEDAI using the REI (all >1.9). Cumulative disease activity as measured by the SLEDAI or the ECLAM are important predictors of damage. There are no statistically important differences between the 2 measures with regard to their ability to predict steroid requirements.

CONCLUSIONS

The ECLAM has construct validity in cSLE and, like the SLEDAI, is highly sensitive to clinically important change in disease activity. The ECLAM may be more responsive. The quantitative properties of the 2 measures are very similar. The SLEDAI likely remains the preferable disease activity measure for cSLE given its overall measurement properties and ease of use.

Antiribosomal P protein antibodies in Chilean SLE patients: no association with renal disease

The objective of this work was to determine the frequency and clinical associations of anti-ribosomal P protein antibodies (Anti-P) in a cohort of Chilean patients with systemic lupus erythematosus (SLE). Between 1996 and 1998, 141 consecutive patients with SLE were examined prospectively according with a standard protocol. Disease activity was measured by MEX-SLEDAI in 138 patients. Anti-P positivity was determined by double immune diffusion or Western blot and ELISA. Anti-P was found in 21 (15%) patients. In the Anti-P positive patients recent onset SLE (disease duration of 1 year or less) was more frequent (P = 0.018). Anti-P was found in 23% of 83 patients with active SLE vs 4% of the 55 patients with inactive SLE (Yates corrected P = 0.00479). An association with anti-dsDNA antibodies by Farr assay was observed. Anti-P positive patients had a median Farr of 65 IU/ml (1.4-1240) and Anti-P negative of 12 IU/ml (1.4-992; P-value = 0.0084). During the study only two patients had lupus psychosis and they were Anti-P positive. No association was found with liver disease (six patients, two with Anti-P antibodies) or active glomerulonephritis (22 patients four with Anti-P). Our data shows that the presence of Anti-P antibodies supports the clinical diagnosis of lupus psychosis.

Diagnostic tests for antiribosomal p protein antibodies: a comparative evaluation of immunoblotting and ELISA assays

We compared the clinical sensitivity and specificity of three different methods for the detection of serum antiribosomal P protein (anti-P) antibodies in systemic lupus erythematosus (SLE). Sera from 60 unselected SLE patients, 100 healthy subjects and 100 patients with other rheumatic inflammatory diseases were screened for anti-P antibodies by immunoblotting (IB) on P proteins from Raji cells and by two ELISA assays, one using the C-terminal 22 aminoacid long synthetic peptide (C-22) of P proteins, the other using a multiple antigen peptide (MAP) carrying four copies of the C-terminal 13 aminoacid long P peptide.Anti-P antibodies were found in 20% lupus sera by IB, 16.7% by MAP ELISA and 11.7% by C-22 ELISA. The specificity for SLE diagnosis of the three tests in healthy subjects and other rheumatic diseases was: 100% by IB, 100% (vs healthy subjects) and 97% (vs rheumatic diseases) by C-22 ELISA, 100% by MAP ELISA. The agreement between methods was good; differences in concordance rates were restricted to weak positivities. We observed a high concordance in the results of IB and ELISA methods for anti-P antibody detection. IB on P proteins extracted from human lymphoid cells is more sensitive than both ELISAs; IB and MAP ELISA perform better than the C-22 ELISA in determining weakly positive sera.

Systemic lupus erythematosus in childhood

Systemic lupus erythematosus is a disease of immune dysregulation that strikes approximately 1 in 2000 individuals. The usual patient is a young woman of child-bearing age; however, this illness affects patients of all ages, ethnic backgrounds, and both sexes. Twenty percent of all cases of lupus are diagnosed during the first two decades of life. Perhaps the most essential point in treating a child with lupus is to be aware and concerned about how to deliver treatment to a patient in the middle of their physical, intellectual, and emotional development.

Neuropsychiatric syndromes in lupus: prevalence using standardized definitions

OBJECTIVE

The San Antonio Lupus Study of Neuropsychiatric Disease is a longitudinal study designed to characterize the spectrum of and important risk factors for specific neuropsychiatric systemic lupus erythematosus (NPSLE) syndromes.

METHODS

Subjects must meet criteria for SLE and must be at least 18 years of age. A standardized medical history, neurologic, rheumatologic, and psychiatric examinations, computerized neuropsychological evaluation, and serologic testing are performed.

RESULTS

This report is based on the first 128 subjects (120 women and 8 men) who completed the initial study visit. Data from this initial study visit were evaluated for the prevalence of NPSLE using the American College of Rheumatology case definitions for 19 NPSLE syndromes. One or more NPSLE syndromes were present in 80% of subjects: cerebrovascular disease (2, 2%; ischemic stroke); headaches (73, 57%); mononeuropathy (9, 8%; median 8, ulnar 1); movement disorder (1, 1%; chorea); neuropathy, cranial (2, 2%; trigeminal); polyneuropathy (29, 22%; sensorimotor); seizures (21, 16%; partial); anxiety disorder (27, 24%); major depressive-like episode (37, 28%); mood disorder with depressive features (21, 19%); mood disorder with manic features (3, 3%); mood disorder with mixed features (1, 1%); psychosis (6, 5%). In a subset of 67 patients who received standardized neuropsychological testing, 21% had normal results. In the remainder, the following levels of impairment were seen: 43% mild, 30% moderate, and 6% severe.

CONCLUSIONS

The prevalence of NPSLE was high in this cohort of unselected patients with SLE. Headaches, cognitive dysfunction, and psychiatric disorders were the most common NPSLE syndromes seen. These results will be easily comparable to other studies also using standardized diagnostic criteria. However, the lack of ethnicity and language-matched normative neuropsychological data may make comparisons of cognitive dysfunction in SLE populations difficult.

Risk factors for damage in childhood-onset systemic lupus erythematosus: cumulative disease activity and medication use predict disease damage

OBJECTIVE

The Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index measures damage in adult patients with systemic lupus erythematosus (SLE), but its usefulness in patients with childhood-onset SLE has not been examined. This study was conducted to evaluate the sensibility of the SLICC/ACR Damage Index, to investigate how cumulative disease activity is related to damage in childhood-onset SLE, and to identify other risk factors for damage in childhood-onset SLE.

METHODS

Disease activity and damage in 66 patients with newly diagnosed childhood-onset SLE were assessed retrospectively, and information on potential risk factors for damage (age, race, sex, medications, duration of disease, hypertension, body mass index, antiphospholipid antibodies, kidney disease, acute thrombocytopenia) was obtained. In addition, a group of physicians was surveyed to establish the sensibility of the SLICC/ACR Damage Index in childhood-onset SLE.

RESULTS

The SLICC/ACR Damage Index was found to have face, content, and construct validity when used in children. The mean SLICC/ACR Damage Index score of the patients was 1.76 (mean followup 3.3 years). Cumulative disease activity over time was the single best predictor of damage (R(2) = 0.30). Other, possibly important risk factors for damage were corticosteroid treatment, the presence of antiphospholipid antibodies, and acute thrombocytopenia. It was determined that immunosuppressive agents may be protective.

CONCLUSION

The SLICC/ACR Damage Index, though useful in childhood-onset SLE, may benefit from the introduction of weightings and redefinition of some of the items. Ongoing disease activity leads to disease damage, and treatment should be prompt. Prolonged use of high-dose corticosteroids may further increase damage, but use of immunosuppressive agents may protect against disease damage; this latter finding may have potential implications for the treatment of childhood-onset SLE and deserves further study. The relationship between disease activity and concomitant use of medication also requires further investigation.

Case series: neuropsychiatric symptoms with pediatric systemic lupus erythematosus

OBJECTIVE

To describe the psychiatric presentation, serologic findings, and neuroimaging patterns in children and adolescents with central nervous system involvement with systemic lupus erythematosus (CNS-SLE).

METHOD

Pediatric patients with psychiatric symptoms who fulfilled the 1997 revised diagnostic American College of Rheumatology criteria for SLE were studied. Complement levels, and anti-double-stranded DNA, anti-Smith, anti-phospholipid, and anti-neuronal antibodies were evaluated. Computed tomography, magnetic resonance imaging, and single photon emission computed tomography (SPECT) neuroimaging studies were reviewed.

RESULTS

The 10 patients with CNS-SLE presented with psychosis, mood disturbance, or confusion, and 8 patients had concomitant neurologic symptoms. The 8 girls and 2 boys ranged in age from 7.5 to 17 years. Serum anti-neuronal antibodies were positive with onset of symptoms and declined with improvement. Initial SPECT was abnormal in all 10 patients and remained abnormal.

CONCLUSION

SPECT and anti-neuronal antibodies help confirm CNS involvement in patients with SLE and neuropsychiatric symptoms.

The use of laboratory tests in the diagnosis of SLE

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

[Clinical significance of antiribosomal antibodies. Study Group on Autoimmunity (GEAI)]

PURPOSE

Autoantibodies directed against the ribosomal P proteins, P0, P1 and P2 (anti-P), have been related to lupus-related psychosis and/or depression. The diagnostic value of antibodies directed against other ribosomal proteins or 28S RNA (anti-no-P) remains unknown. A multicenter study including ten centers belonging to the study group for autoimmune diseases (GEAI) was conducted in order to determine the diagnostic value of anti-P and anti-no-P antibodies in a large population of patients.

METHODS

The patients were selected on the basis of the presence of serum anti-ribosomal antibodies detected by indirect immunofluorescence (IF) on rat liver/kidney/stomach/pancreas sections and human HEp2 cells. The clinical course of all patients was studied using a predetermined survey. The specificity of anti-P antibodies were determined by Western blot.

RESULTS

Anti-ribosomal antibodies were found in 82 patients. Fifty-five of them had systemic lupus erythematosus and 27 had another disease. Only 54% of the anti-ribosomal antibodies detected by IF were anti-P and were found in 69% of the patients with systemic lupus erythematosus. Anti-no-P antibodies (46%) were preferably detected in patients who suffered from another disease (78%). In patients with systemic lupus erythematosus, neurological and psychiatric disorders were more frequent in the no-P group (47% vs. 16%, P < 0.01) than arthritis, which was found more frequently in the P group (78% vs. 53%, P < 0.05).

CONCLUSION

Anti P antibodies do not constitute a specific diagnostic marker of systemic lupus erythematosus, and lupus-related neuropsychiatric disorders would be preferably associated with the presence of anti no-P antibodies.

The clinical relevance of antibodies to ribosomal-P common epitope in two targeted systemic lupus erythematosus populations: a large cohort of consecutive patients and patients with active central nervous system disease

OBJECTIVES

To develop an enzyme linked immunosorbent assay (ELISA) using as substrate a synthetic 22-aminoacid peptide, corresponding to the ribosomal P0, P1 and P2 common epitope. To study the specificity and sensitivity of the method and evaluate the frequency and clinical associations of anti-P antibodies in two groups of systemic lupus erythematosus (SLE) patients: (a) unselected SLE patients and (b) SLE patients with central nervous system (CNS) involvement.

PATIENTS AND METHODS

The C-terminal 22 aminoacid peptide of the ribosomal P proteins (Lys-Lys-Glu-Glu-Lys-Lys-Glu-Glu-Lys-Ser-Glu-Glu-Glu-Asp-Glu-Asp-Met- Gly-Phe-Gly-Leu-Phe-Asp) was synthesised according to Merrifield's solid phase procedure. Purification of the peptide was performed by preparative high performance liquid chromatography and confirmed by amino acid analysis. Using this peptide, in a concentration 5 microg/ml, an ELISA was developed. The presence of anti-P antibodies was evaluated by western blot using purified ribosomal proteins from rat liver. Sera from 178 consecutive patients with SLE and 28 patients with SLE and CNS manifestations were tested. Sera from 58 patients with rheumatoid arthritis and 57 patients with primary Sjögren's syndrome were used as controls. The cut off point of the assay was defined using 124 normal sera.

RESULTS

The specificity of the assay was evaluated by homologous inhibition. Pretreatment of positive sera with soluble 22mer peptide of the ribosomal P proteins resulted in 88% inhibition. The concordance between the peptide assay and western blot was found to be 83%. Thirty three of 178 (18. 6%) of the unselected SLE patients had antibodies to P-protein common epitope. Their presence was associated with more active disease (European Consensus Lupus Activity Measurement, ECLAM scoring system) (p<0.001), higher levels of anti-ds DNA antibodies (p<0.05) and lower levels of the C4 component of complement (p<0.01). Eleven of 28 (39.3%) patients with SLE and active CNS involvement had antibodies to P-protein. The overall prevalence of anti-P antibodies in active CNS disease patients was statistically significantly higher, as compared with unselected SLE patients (chi(2)=6.04, p<0.05). These antibodies were found in a high proportion of patients without anticardiolipin antibodies (52.4%) and they were associated with diffuse CNS involvement (psychiatric disorders (71%) and epilepsy (75%)).

CONCLUSIONS

A synthetic analogue of the common epitope of ribosomal P-proteins can be use as an antigen for the detection of anti-P antibodies. These antibodies are associated with active SLE and CNS involvement particularly in patients without anticardiolipin antibodies.

Prevalence of autoantibodies to ribosomal P proteins in juvenile-onset systemic lupus erythematosus compared with the adult disease

OBJECTIVE

To determine the prevalence of anti-ribosomal P (anti-P) proteins in several groups of patients with juvenile-onset systemic lupus erythematosus (SLE) in comparison with the prevalence in adult SLE.

METHODS

Serum samples were pooled together from 3 cohorts of patients with juvenile-onset SLE in 3 different medical centers and from a miscellaneous group of juvenile-onset SLE patients whose samples were sent by regional physicians. Sera were studied for the presence of anti-P using 2 assays: Western blot with ribosomes as antigen, and an enzyme-linked immunosorbent assay with the COOH-terminal 22 amino acids of the ribosomal P protein in a multiantigenic peptide format as antigen. Sera found positive by both tests were considered positive for anti-P antibodies. Findings from similar studies involving a large cohort of patients with adult-onset SLE from Oklahoma City were used for comparison.

RESULTS

The prevalence of anti-P antibodies in the pooled sample of juvenile-onset SLE sera was 45 of 108, or 42%, while in the adult cohort from Oklahoma City, 20 of 260, or 7.7%, were positive for anti-P (odds ratio [OR] 9.6, P < 10(-8) by Fisher's exact test). In addition, it was shown that 12 of 13 patients with both anti-P and anti-double-stranded DNA (anti-dsDNA) in the juvenile SLE cohort had nephritis, while only 8 of 22 patients without both antibodies were nephritic (OR 21.0, P < 10(-8)). It was also shown that in 9 illustrative cases, the levels of anti-P and anti-dsDNA antibodies usually varied together and in concordance with the clinical activity as measured by the SLE Disease Activity Index (SLEDAI). Finally, anti-P-positive and anti-P-negative patients had a similar prevalence of anti-dsDNA, anti-Ro/SSA, and anti-La/SSB antibodies, but patients with anti-P had a higher prevalence of anti-U1 RNP and anti-Sm (P = 0.041 and P = 0.0385, respectively, by Fisher's exact test).

CONCLUSION

Antibodies to ribosomal P protein are more prevalent in juvenile-onset SLE than in adult-onset SLE. Levels of antibodies to ribosomal P protein vary with the clinical disease activity as measured by the SLEDAI, often in concordance with the levels of anti-dsDNA. The presence of both anti-P and anti-dsDNA antibodies was powerfully associated with nephritis in the cohort of patients for whom comprehensive clinical and serologic data were available.

The presence of masked antiribosomal P autoantibodies in healthy children

OBJECTIVE

To determine if antiribosomal P (anti-P) autoantibodies are present in healthy children.

METHODS

Sera from healthy children were screened for anti-P by conventional enzyme-linked immunosorbent assay and immunoblot techniques. Sera were also treated with immobilized ribosomal P antigens on nitrocellulose strips; affinity-purified fractions were tested for anti-P by high-sensitivity immunoblot. The relative binding affinities were compared for affinity-purified anti-P antibodies from healthy children and adults, and patients with systemic lupus erythematosus. IgG fractions of anti-P-depleted sera from healthy children were assessed for inhibition of autologous anti-P activity.

RESULTS

Conventional serologic screening showed no IgG nor IgM anti-P in 88 untreated sera. IgG anti-P were unmasked in all 79 sera treated by the membrane batch affinity technique. IgM anti-P were identified in 27 of the treated sera; the percentage of positive sera decreased with increasing age (chi(2) for linear trend P = 0.00081). Affinity-purified anti-P from children had relative binding affinities similar to those of anti-P from other groups. Sera from healthy children contained inhibitory IgG antibodies to anti-P.

CONCLUSION

These results show that anti-P autoantibodies are present in all healthy children. The majority of these autoantibodies are masked by IgG antibodies, suggesting concordant development of a regulatory network.

Anti-P antibodies and neuropsychiatric lupus erythematosus

A high proportion of patients with SLE develop neuropsychiatric lupus during the course of their disease. The expression of disease varies significantly in terms of clinical manifestations, onset, and severity, so that this form of lupus remains a major diagnostic and therapeutic challenge. Because affected tissue cannot be sampled and animal models are not readily available, scientific investigation is considerably hampered. Approximately 15% of lupus patients have anti-P antibodies. These autoantibodies are highly specific for SLE. Most series show a highly significant association between anti-P and lupus psychosis, and this result is now confirmed in a series of 336 SLE patients. The mechanism explaining this association is uncertain and may simply reflect an immune response to damaged tissue. However, the possibility that the antibodies are pathogenic by directly binding to cell-surface receptors on neuronal cells or that they penetrate cells and inhibit protein synthesis within the cell requires further investigation. Whether T cells are involved in the pathogenesis of CNS disease is an important question that has received little attention. As in the CNS of patients with multiple sclerosis and patients with other autoimmune diseases, excess production of cytokines may contribute significantly to organ inflammation. We report associations between anti-P autoantibodies and certain MHC class II alleles, particularly HLA-DQB1*0602. These findings support a role for T cells in anti-P autoantibody production and encourage further studies of the role of autoantigen-specific T and B cells in injury to the central nervous system.

Ribosomal P autoantibodies in systemic lupus erythematosus. Frequencies in different ethnic groups and clinical and immunogenetic associations

OBJECTIVE

To determine the frequencies and clinical associations of antiribosomal P antibodies (anti-P) in a large multiethnic cohort of patients with systemic lupus erythematosus (SLE), and to assess whether anti-P was associated with any major histocompatibility complex (MHC) class II alleles or shared amino acid sequences.

METHODS

Sera from 394 SLE patients were studied for anti-P using an enzyme-linked immunosorbent assay, and MHC class II alleles (HLA-DRB1, DQA1, and DQB1) were determined by DNA oligotyping.

RESULTS

Anti-P antibodies were found in 13-20% of patients in the majority of ethnic groups, but were perhaps more frequent in Chinese patients (36%) and less common in Bulgarian patients (6%). Neuropsychiatric lupus (psychosis and/or depression) was significantly associated with anti-P. The HLA-DR2, DQ6 haplotypes DRB1*1501 or *1503, DQA1*0102, and DQB1*0602 were increased in anti-P-positive whites, blacks, and Mexican Americans. The HLA-DQB1*0602 allele showed the strongest association with anti-P when these 3 ethnic groups were combined and compared with both race-matched anti-P-negative SLE patients and normal controls. The HLA-DQ8 specificity (DQB1*0302) was increased both in whites and in Mexican-Americans with anti-P who were negative for HLA-DQB1*0602, and perhaps also increased in Greeks, but not in blacks, in whom HLA-DQB1*0301 was increased. A shared amino acid sequence in HLA-DQB1 (at position 26 of leucine and position 30 of tyrosine) was strongly associated with anti-P positivity (70%) versus anti-P negativity (42%) across ethnic lines.

CONCLUSION

The anti-P response in SLE patients, occurring in approximately 15% of patients, was strongly influenced by certain MHC class II alleles and was correlated with diffuse neuropsychiatric dysfunction.