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

[Characteristics of serum autoantibodies in patients with lupus nephritis and tubulointerstitial damage]

OBJECTIVE

To observe the tubulointerstitial damage (TID) in lupus nephritis (LN) and investigate the relationship between autoantibodies and TID in lupus nephritis.

METHODS

This cross-sectional study was conducted in a comprehensive tertiary hospital in Peking University Shenzhen Hospital. From March 2012 to July 2021, LN patients who performed renal biopsy were enrolled in the study. Clinical, laboratory and pathology data were collected. We classified the patients into none-or-mild group and moderate-to-severe groups according to the severity of interstitial fibrosis (IF) /tubular atrophy (TA) or tubulointerstitial inflammation (TII). The t test, U test and Chi-square test were used for statistical analysis as appropriate.

RESULTS

A total of 226 patients were included, of who 190 (84%) were female with a median age of 32 (26, 39) years. 89% (201/226) of the patients who pathologically proved to be proliferative LN by renal biopsy. The frequency of moderate-to-severe TII and moderate-to-severe IF/TA was 30% (67/226) and 34% (76/226) respectively. For autoantibodies, the patients with moderate-to-severe TII had a lower rate of positive serum anti-ribonucleoprotein (anti-RNP) antibodies than the patients with none-or-mild TII (34% vs. 51%), and moderate-to-severe IF/TA had a lower rate of positive anti-ribosomal P protein (anti-P) antibodies than patients with none-or-mild IF/TA (19% vs. 33%). For other clinical indicators, the patients with moderate-to-severe TII and moderate-to-severe IF/TA were more often combined with proliferative LN, hypertension and anemia than the patients with none-or-mild TII and none-or-mild IF/TA, respectively. The patients with moderate-to-severe TII had higher serum creatinine values and lower glomerular filtration rates than the patients with none-or-mild TII. The patients with moderate-to-severe IF/TA had higher serum creatinine values, and lower glomerular filtration rates than the patients with none-or-mild IF/TA.

CONCLUSION

In patients with LN in Southern China, anti-RNP antibodies and anti-P antibodies may be potential protective factors for TII and IF/TA, respectively. More studies are needed to identify the risk factors of lupus patients with TID and investigate the correlation between autoantibodies and TID, which are critical for developing better preventive and therapeutic strategies to improve the survival rate of LN.

IKBKE and BANK1 Polymorphisms and Clinical Characteristics in Chinese Women with Systemic Lupus Erythematosus

BACKGROUND

Defects in apoptotic cell clearance is a pathogenic factor in systemic lupus erythematosus (SLE). This study screened potential pathogenic single nucleotide polymorphisms (SNPs) related to anti-apoptosis from an SLE family and explored their contribution to SLE susceptibility in Chinese women.

METHODS

Four SNPs (IKBKE rs15672, BANK1 rs12640056, BANK1 rs6842661, and NFKBIA rs1957106) with potential SLE susceptibility were analyzed for clinical characteristics between 567 patients with SLE and 345 healthy control subjects.

RESULTS

IKBKE rs15672 G/A and BANK1 rs12640056C/T polymorphisms were associated with SLE susceptibility (rs15672 A vs G, P = 0.028, OR = 1.25, 95% CI = 1.02-1.52; rs12640056 T vs C, P = 0.015, OR = 0.78, 95% CI = 0.64-0.95, respectively). In addition, patients with AA+GA genotypes of IKBKE rs15672 had higher positive rates of anti-SSB antibodies (q = 0.008) and lower positive rates of anti-RIB antibodies (q = 0.024) than those with the GG genotype. There were no significant differences in BANK1 rs12640056 between different genotypes and clinical characteristics.

CONCLUSION

IKBKE rs15672 G/A and BANK1 rs12640056C/T polymorphisms are associated with susceptibility to SLE in Chinese women. This highlights the important role of these two SNPs in this disease and suggests that multiple genes from these pathways are candidates for functional studies and therapeutic targets.

A nomogram to predict the risk of lupus enteritis in systemic lupus erythematosus patients with gastroinctestinal involvement

BACKGROUND

Lupus enteritis (LE), a main cause of acute abdominal pain in systemic lupus erythematosus (SLE) patients, is a serious and potentially fatal complication. This study aimed to identify clinical serological indicators to establish a nomogram to assess LE in SLE patients with gastrointestinal manifestations.

METHODS

The clinical and laboratory data of SLE patients with gastrointestinal manifestations that were hospitalized in the West China Hospital from January 2010 to January 2020 were retrospectively analyzed. The least absolute shrinkage and selection operator logistic regression model was used to select potentially relevant features. Subsequently, a nomogram was developed using multivariable logistic analysis. The performance of the nomogram was evaluated using a receiver operating characteristic curve, a calibration curve, and decision curve analysis (DCA).

FINDINGS

We included a total of 8,505 SLE patients, of which 251 had experienced gastrointestinal manifestations. The patients were randomly divided into training (n = 176) and validation (n = 75) groups. The LRA (LE Risk Assessment) model consisted of 11 significantly associated variables, which included complement 4, antineutrophil cytoplasmic antibody, albumin, anion gap, age, d-dimer, platelet, serum chlorine, anti-Sjögren's-syndrome-related antigen A, anti-ribosomal P protein, and anti-ribonucleoprotein. In the training and validation cohorts, the areas under the curve were 0.919 (95% confidence interval [CI]: 0.876-0.962) and 0.870 (95% CI: 0.775-0.964), respectively. The nomogram demonstrated excellent performance in the calibration curve and DCA.

INTERPRETATION

The LRA model exhibits good predictive ability in assessing LE risk in SLE patients with gastrointestinal manifestations.

Autoantibodies associated with primary biliary cholangitis are common among patients with systemic lupus erythematosus even in the absence of elevated liver enzymes

Knowledge of concomitant autoimmune liver diseases (AILD) is more detailed in primary Sjögren's syndrome (pSS) compared to systemic lupus erythematosus (SLE). Herein, the prevalence of autoantibodies associated with autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) was investigated in stored sera from patients with SLE (n = 280) and pSS (n = 114). Antibodies against mitochondria (AMA), liver-kidney microsomal (LKM) antigen, smooth muscle (SMA) and anti-nuclear antibodies (ANA) were analysed with immunofluorescence microscopy. In addition, AILD-associated autoantibodies were tested with immunoblot. Prior to sampling, eight SLE (2·9%) and three pSS (2·6%) cases were diagnosed with AILD. Among SLE-cases without known AILD (n = 272), 26 (9·6%) had PBC-associated autoantibodies, 15 (5·5%) AIH-associated autoantibodies (excluding ANA) and one serological overlap. Most subjects with PBC-associated autoantibodies had liver enzymes within reference limits (22 of 27, 81%) or mild laboratory cholestasis (two of 27, 7·4%), while one fulfilled the diagnostic PBC-criteria. AMA-M2 detected by immunoblot was the most common PBC-associated autoantibody in SLE (20 of 272, 7·4%). The prevalence of SMA (4·4%) was comparable with a healthy reference population, but associated with elevated liver enzymes in four of 12 (25%), none meeting AIH-criteria. The patient with combined AIH/PBC-serology had liver enzymes within reference limits. Among pSS cases without known AILD (n = 111), nine (8·1%) had PBC-associated, 12 (10·8%) AIH-associated autoantibodies and two overlapped. PBC-associated autoantibodies were found as frequently in SLE as in pSS but were, with few exceptions, not associated with laboratory signs of liver disease. Overall, AILD-associated autoantibodies were predominantly detected by immunoblot and no significant difference in liver enzymes was found between AILD autoantibody-negative and -positive patients.

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.

The Bidirectional Relationship of Depression and Inflammation: Double Trouble

Depression represents the number one cause of disability worldwide and is often fatal. Inflammatory processes have been implicated in the pathophysiology of depression. It is now well established that dysregulation of both the innate and adaptive immune systems occur in depressed patients and hinder favorable prognosis, including antidepressant responses. In this review, we describe how the immune system regulates mood and the potential causes of the dysregulated inflammatory responses in depressed patients. However, the proportion of never-treated major depressive disorder (MDD) patients who exhibit inflammation remains to be clarified, as the heterogeneity in inflammation findings may stem in part from examining MDD patients with varied interventions. Inflammation is likely a critical disease modifier, promoting susceptibility to depression. Controlling inflammation might provide an overall therapeutic benefit, regardless of whether it is secondary to early life trauma, a more acute stress response, microbiome alterations, a genetic diathesis, or a combination of these and other factors.

Neuropsychiatric lupus: new mechanistic insights and future treatment directions

Patients with systemic lupus erythematosus (SLE) frequently show symptoms of central nervous system (CNS) involvement, termed neuropsychiatric SLE (NPSLE). The CNS manifestations of SLE are diverse and have a broad spectrum of severity and prognostic implications. Patients with NPSLE typically present with nonspecific symptoms, such as headache and cognitive impairment, but might also experience devastating features, such as memory loss, seizures and stroke. Some features of NPSLE, in particular those related to coagulopathy, have been characterized and an evidence-based treatment algorithm is available. The cognitive and affective manifestations of NPSLE, however, remain poorly understood. Various immune effectors have been evaluated as contributors to its pathogenesis, including brain-reactive autoantibodies, cytokines and cell-mediated inflammation. Additional brain-intrinsic elements (such as resident microglia, the blood-brain barrier and other neurovascular interfaces) are important facilitators of NPSLE. As yet, however, no unifying model has been found to underlie the pathogenesis of NPSLE, suggesting that this disease has multiple contributors and perhaps several distinct aetiologies. This heterogeneity presents a challenge for clinicians who have traditionally relied on empirical judgement in choosing treatment modalities for patients with NPSLE. Improved understanding of this manifestation of SLE might yield further options for managing this disease.

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.

Neuropsychiatric SLE: from animal model to human

Animal models are a key element in disease research and treatment. In the field of neuropsychiatric lupus research, inbred, transgenic and disease-induced mice provide an opportunity to study the pathogenic routes of this multifactorial illness. In addition to achieving a better understanding of the immune mechanisms underlying the disease onset, supplementary metabolic and endocrine influences have been discovered and investigated. The ever-expanding knowledge about the pathologic events that occur at disease inception enables us to explore new drugs and therapeutic approaches further and to test them using the same animal models. Discovery of the molecular targets that constitute the pathogenic basis of the disease along with scientific advancements allow us to target these molecules with monoclonal antibodies and other specific approaches directly. This novel therapy, termed "targeted biological medication" is a promising endeavor towards producing drugs that are more effective and less toxic. Further work to discover additional molecular targets in lupus' pathogenic mechanism and to produce drugs that neutralize their activity is needed to provide patients with safe and efficient methods of controlling and treating the disease.

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.

A Systematic Review of Peripheral and Central Nervous System Involvement of Rheumatoid Arthritis, Systemic Lupus Erythematosus, Primary Sjögren's Syndrome, and Associated Immunological Profiles

Both central (CNS) and peripheral nervous system (PNS) complications are frequent and varied in connective tissue diseases. A systematic review was conducted between 1989 and 2014 in the databases Medline, Scopus, and Cochrane Library using the search terms, peripheral and central nervous complications and immunological profiles, to identify studies in specific connective tissue disorders such as rheumatoid arthritis, systemic lupus erythematosus, and primary Sjögren's syndrome. A total of 675 references were identified, of which 118 were selected for detailed analysis and 22 were included in the final review with a total of 2338 participants. Our search focused only on studies upon connective tissue disorders such as rheumatoid arthritis, systemic lupus erythematosus, and primary Sjögren's syndrome associated with seroimmunological data. The reported prevalence of CNS involvement ranges from 9 to 92% across the reported studies. However, the association between CNS and PNS manifestations and seroimmunological profiles remains controversial. Τo date, no laboratory test has been shown as pathognomonic neither for CNS nor for PNS involvement.

The association of serum anti-ribosomal P antibody with clinical and serological disorders in systemic lupus erythematosus: a systematic review and meta-analysis

Objective

Anti-ribosomal P (anti-P) antibody is a serological specific marker of systemic lupus erythematosus (SLE). The aim of this study is to investigate the association of this antibody with clinical and serological disorders in SLE.

Methods

All relevant literature was retrieved from PubMed, EMBASE, Web of Science and CNKI databases. The qualities of these studies were evaluated using a modified version of the Newcastle–Ottawa scale. The associations of anti-P antibody with clinical and serological disorders were determined by the pooled odds ratio (OR) and the confidence interval (CI) calculated using meta-analysis with the Mantel–Haenszel method.

Results

Sixteen cohort studies with 2355 patients were included in this study. Malar rash, oral ulcer and photosensitivity were strongly associated with serum anti-P antibody, with OR (95% CI) values of 2.05 (1.42–2.92), 1.49 (1.05–2.13) and 1.44 (1.08–1.91), respectively. Arthritis and renal involvement were not associated with anti-P antibody, whereas a high heterogeneity was observed due to ethnicity and publication bias, respectively. Neuropsychiatric SLE (NPSLE), hepatic involvement, anti-dsDNA, anti-Sm and anti-cardiolipin antibodies (aCL) were observed more frequently in anti-P positive patients than in negative patients. Studies on hepatic involvement showed a low precision with substantially broad CI (2.56–11.2). A high heterogeneity presented among studies on NPSLE, anti-Sm and aCL.

Conclusions

Anti-P antibody is significantly associated with malar rash, oral ulcer, photosensitivity and serum anti-dsDNA antibody, and potentially associated with NPSLE, hepatic damage, serum anti-Sm and aCL.

The importance of cytokines and autoantibodies in depression

The relationship between depression and immunity has been widely discussed. Cytokines, such as TNF-α, play an important role in immune system; these cytokines interact with virtually every pathophysiologic domain relevant to depression, including neurotransmitter metabolism, neuroendocrine function, and synaptic plasticity. Antibodies have also been implicated in the pathophysiology of depression. The association between decreased serotonin levels and excessive glutamatergic activity forms the first biochemical basis for cytokine-induced depression. Cytokines and antibodies (anti-ribosomal-P and anti-N-methyl-D-aspartate receptor antibodies) are deeply related to pathogenesis of neurodevelopmental disorders, especially depression. Tumor necrosis factor alpha (TNF-α) may underlie the mechanism of depression by an activation of the hypothalamo-pituitary-adrenocortical (HPA) axis, an activation of neuronal serotonin transporters and the stimulation of the indoleamine 2,3-dioxygenase which leads to tryptophan depletion. In the last 20 years since the initial reports of neural-immune interactions in depression, studies have shown a clear association between activation of the immune system mediated by proinflammatory cytokines. Genes encoding cytokines are highly polymorphic and single nucleotide polymorphisms, associated with increased or reduced cytokine production, have been described. To date, there are only few studies that investigated the relationship between depression and proinflammatory cytokines in patients with autoimmune diseases. Although an associative link between neuroinflammation and mood disorders is widely accepted, further studies are necessary to establish the cause-effect relationship. In this paper, we review the role of cytokines, focusing on TNF-α and antibodies in the depression and hypothesize how TNF-α may underlie and mediate the inflammatory process depression in patients with autoimmune disease.

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.

Incidence and prevalence of major central nervous system involvement in systemic lupus erythematosus: a 3-year prospective study of 370 patients

Background

The incidence and prevalence of CNS involvement in SLE remains unclear owing to conflicting results in the published studies. The aim of the study was to evaluate the incidence and prevalence of major definite CNS events in SLE patients.

Methods

370 SLE patients with no previous history of CNS involvement were prospectively evaluated in a tertiary hospital referral center for 3 years. Major CNS manifestations were codified according to ACR definitions, including chorea, aseptic meningitis, psychosis, seizures, myelopathy, demyelinating syndrome, acute confusional state and strokes. Minor CNS events were excluded. ECLAM and SLEDAI-SELENA Modification scores were used to evaluate disease activity and SLICC/ACR Damage Index was used to assess accumulated damage.

Results

16/370 (4.3%) patients presented with a total of 23 major CNS events. These included seizures (35%), strokes (26%), myelopathy (22%), optic neuritis (8.7%), aseptic meningitis (4.3%) and acute psychosis (4.3%). Incidence was 7.8/100 person years. Among hospitalizations for SLE, 13% were due to CNS manifestations. Epileptic seizures were associated with high disease activity, while myelopathy correlated with lower disease activity and NMO-IgG antibodies (P≤0.05). Stroke incidence correlated with APS coexistence (P = 0.06). Overall, CNS involvement correlated with high ECLAM and SLEDAI scores (P<0.001).

Conclusions

Clinically severe CNS involvement is rare in SLE patients, accounting for 7.8/100 person years. CNS involvement correlates with high disease activity and coexistence of specific features that define the respective CNS syndromes.

Significance of antibodies against the native ribosomal P protein complex and recombinant P0, P1, and P2 proteins in the diagnosis of Chinese patients with systemic lupus erythematosus

BACKGROUND

This study aimed to evaluate autoantibodies against the native ribosomal P complex (anti-Rib-P(C)) and recombinant ribosomal P proteins (anti-Rib-P0, anti-Rib-P1, anti-Rib-P2) for their prevalence, diagnostic relevance and clinical associations in a Chinese cohort with systemic lupus erythematosus (SLE).

METHODS

Anti-Rib-P, anti-dsDNA and anti-Smith antigen (Sm) antibodies were analyzed in sera from 198 patients with SLE, 33 with rheumatoid arthritis, 61 with Sjögren's syndrome and 70 healthy individuals by means of ELISA.

RESULTS

Antibody prevalences were 29.8% (anti-Rib-P(C)), 33.3% (anti-Rib-P0), 42.9% (anti-Rib-P1) and 34.3% (anti-Rib-P2), at a specificity of 99%. Among SLE patients lacking anti-dsDNA and anti-Sm, 27.8% showed positive for at least one of the investigated anti-Rib-P types. The serological hit rate provided by anti-dsDNA/anti-Sm detection (72.7%) was increased upon parallel testing for anti-Rib-P(C) (77.3%) or anti-Rib-P0/P1/P2 (80.3%). Anti-Rib-P positivity was associated with disease activity, neuropsychiatric events, lupus nephritis, skin rash, lymphocytopenia, increased erythrocyte sedimentation rates, decreased complement C3/C4 and elevated IgA/IgG levels.

CONCLUSION

Based on these results, antibodies against ribosomal P proteins are important complementary parameters to anti-dsDNA and anti-Sm, and should be considered for inclusion in the classification criteria for SLE. The diagnostic value of anti-Rib-P0/P1/P2 is diagnostically superior to that of anti-Rib-P(C).

A 17-Year-Old Female with Systemic Lupus Presents with Complex Movement Disorder: Possible Relationship with Antiribosomal P Antibodies

Complex movement disorder is a relatively rare presentation of neurolupus. Antiphospholipid antibodies are associated with movement disorders likely via aberrant neuronal stimulation. Antiribosomal P antibodies have been previously associated with neuropsychiatric disorders but their correlation with movement disorder was not previously established. Our case report involves a 17-year-old Caucasian female patient positive for only antiribosomal P antibody and lupus anticoagulant who presented with a sudden onset of complex movement disorder. After complete cessation of physical signs with olanzapine, anticardiolipin and anti-β2 glycoprotein I antibodies became positive which indicates a likely discordance between movement disorder and antiphospholipid antibodies. This also indicates a potential causal role of antiribosomal P antibodies in inducing movement disorder.

Autoantibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial disorder with multigenic inheritance and various environmental factors implicated in its aetiopathogenesis. Despite the multiple mechanisms involved in the aetiology of SLE being elusive, recent studies have made progress in our understanding of the pathogenic mechanisms via abnormal regulation of cell-mediated and humoral immunity that lead to tissue damage. The heterogeneity of the clinical manifestations probably reflects the complexity of the disease pathogenesis itself. The immune system in SLE is characterised by a complex interplay between overactive B cells, abnormally activated T cells and antigen-presenting cells. This interplay leads to the production of an array of inflammatory cytokines, apoptotic cells, diverse autoantibodies and immune complexes that in turn activate effector cells and the complement system, leading to tissue injury and damage which are the hallmarks of the clinical manifestations. SLE patients have dysregulation of inflammatory cytokines, chemokines and immune response-related genes, as well as of the genes involved in apoptosis, signal transduction and the cell cycle.

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.

Diagnostic value and clinical laboratory associations of antibodies against recombinant ribosomal P0, P1 and P2 proteins and their native heterocomplex in a Caucasian cohort with systemic lupus erythematosus

Introduction

In this study, we sought to determine the diagnostic value and clinical laboratory associations of autoantibodies against recombinant ribosomal P0, P1 and P2 proteins and their native heterocomplex in systemic lupus erythematosus (SLE).

Methods

Autoantibodies against recombinant ribosomal P proteins (aRibP_R0, aRibP_R1 and aRibP_R2) and antibodies against native ribosomal P heterocomplex (aRibP_NH) were determined in sera from patients with SLE (n = 163), systemic sclerosis (n = 66), Sjögren's syndrome (n = 54), rheumatoid arthritis (n = 90) and healthy donors (n = 100) using enzyme-linked immunosorbent assay. Test results were correlated to medical records, including the American College of Rheumatology criteria, the Systemic Lupus Erythematosus Disease Activity Index 2000, laboratory data and medications of all SLE patients.

Results

Sensitivities of 22.0% for aRibP_R0, 14.9% for aRibP_R2, 14.3% for aRibP_NH and 10.7% for aRibP_R1 were obtained at a specificity of 99%. The assay for aRibP_R0 detection demonstrated the best performance in receiver-operating characteristics analysis, with aRibP_R0 detectable in 10% of anti-Smith antibody and anti-double-stranded DNA-negative sera at a specificity of 100%. ARibP_R0 positivity was associated with lymphocytopenia. ARibP_R1⁺ patients had significantly higher γ-glutamyl transpeptidase (GGT) levels than their aRibP_R1^- counterparts. No specific damage occurred in aRibP⁺ lupus patients compared with a group of age-, sex- and nephritis-matched aRibP^- lupus patients within 3 years.

Conclusions

The determination of antibodies against ribosomal P proteins improves the diagnosis of SLE and should therefore be implemented in upcoming criteria for the diagnosis or classification of SLE. High titers of aRibP_R0 can be associated with lymphocytopenia, and high titers of aRibP_R1 can be associated with elevated GGT levels. So far, there is no evidence for a prognostic value of aRibPs for damage.

The role of measurement of serum autoantibodies in prediction of pediatric neuropsychiatric systemic lupus erythematosus

Neuropsychiatric systemic lupus erythematosus (NPSLE) is one of the most difficult manifestations of lupus to diagnose. Measurement of serum brain antibodies has contributed to early diagnosis and management of NPSLE before development of a debilitating disease. We aimed to assess the value of serum anti-ganglioside M1 antibodies in prediction of NPSLE, in comparison to other antibodies used in routine laboratory diagnosis of NPSLE. In addition, we are the first to study the relationship between these antibodies and cognitive function in lupus patients. Serum anti-ganglioside M1, anti-ribosomal P protein and anti-cardiolipin antibodies were measured in 30 lupus patients without clinical evidence of NPSLE, aged 8-16 years, and 30 healthy matched-subjects. Patients were followed-up clinically by monthly neuropsychiatric evaluation and assessment of cognitive function for 12 months. Twelve patients developed neuropsychiatric manifestations during follow-up. Of those patients, 83.3%, 50% and 16.7% were seropositive for anti-ganglioside M1, anti-ribosomal P and anti-cardiolipin antibodies, respectively at the time of initial evaluation before clinical presentation of NPSLE. There was a significant positive association between anti-ganglioside seropositivity and cognitive dysfunction (P<0.001). In addition, anti-ganglioside seropositivity had a significant risk for association with cognitive dysfunction (odds ratio: 36; 95% CI: 4.3-302.8).

CONCLUSIONS

Serum anti-ganglioside M1 antibodies had a higher predictive value for NPSLE than other antibodies used in routine laboratory diagnosis of this disease. Thus, they may be reliable parameters for early diagnosis and management of NPSLE before clinical manifestations ensue. In addition, anti-ganglioside M1 antibodies may play a role in cognitive dysfunction found in some lupus patients.

Cutaneous vasculitis in systemic lupus erythematosus: association with anti-ribosomal P protein antibody and Raynaud phenomenon

Ninety-one consecutive systemic lupus erythematosus (SLE) patients (American College of Rheumatology criteria) with a history of cutaneous vasculitis were compared to 163 SLE controls without this clinical manifestation from July to December 2007 in order to determine the possible clinical and serological association of this manifestation. Data were obtained in an ongoing electronic database protocol and autoantibodies to anti-double-stranded DNA, anti-Sm, anti-RNP, anti-Ro/SS-A, anti-La/SS-B, and anticardiolipin and ribosomal P protein antibody (anti-P) were detected by standard techniques. Exclusion criteria were the presence of anti-phospholipid syndrome or antibodies, Sjögren syndrome, and a history of thrombosis. The mean age (38.5 ± 11.5 vs. 37.8 ± 11.6 years, p = 0.635), disease duration (12.5 ± 7.8 vs. 11.8 ± 7.9 years, p = 0.501), and frequency of white race (71.4% vs. 70.5%, p = 0.872) and female sex (96.8% vs. 93.7%, p = 0.272) were comparable in both groups. The vasculitis group had a higher frequency of malar rash (97.9% vs. 87.4%, p = 0.004), photosensitivity (91.4% vs. 81.6%, p = 0.030), and Raynaud phenomenon (RP; 27.7% vs. 7.5%, p < 0.001), whereas all other clinical manifestation including renal and central nervous system involvements were similar to the control group. Laboratorial data revealed that only anti-P (35.1% vs. 12.1%, p < 0.001) was more frequent in patients with vasculitis. In a multivariate logistic regression model, cutaneous vasculitis was associated to the presence of RP (OR = 3.70; 95% confidence interval [CI] = 1.73-8.00) and anti-P (OR = 3.42; 95% CI = 1.76-6.66). In summary, SLE cutaneous vasculitis characterizes a subgroup of patients with more RP and anti-P antibodies but not accompanied by a higher frequency of renal and central nervous system involvements.

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.

Clinical and diagnostic value of ribosomal P autoantibodies in systemic lupus erythematosus

OBJECTIVE

To analyse prospectively the diagnostic sensitivity and specificity as well as the clinical relevance of ribosomal P (anti-P) autoantibodies in a large cohort of SLE patients.

METHODS

The anti-P autoantibodies were evaluated in the serum of 200 Tunisian SLE patients at disease onset and 130 various control subjects by a sensitive immunodot assay. A complete laboratory evaluation and clinical examination were performed in each SLE patient. During the follow-up, the patients were regularly monitored for clinical parameters. Global SLE activity was measured by the ECLAM.

RESULTS

The sensitivity and specificity of anti-P testing for SLE were 23.5 and 98.4%, respectively. The anti-P-positive samples 14/47 (29.8%), 27/47 (57.4%) and 5/47 (10.6%) were negative for anti-dsDNA, anti-Sm or both antibodies, respectively. The anti-P-positive patients showed more active disease activity and a much higher prevalence of arthritis. An association between IgG aCLs and anti-P antibodies was also found. However, anti-P antibodies were not associated with neuropsychiatric manifestations or lupus nephritis.

CONCLUSION

This study does not seem to confirm the described association of anti-P antibodies with neuropsychiatric manifestations of SLE. However, it supports the anti-P antibody association with arthritis and disease activity as well as the presence of aCL. Based on our study and other related studies, we propose that, akin to anti-Sm and anti-dsDNA, anti-P antibodies detected by one agreed method may be considered for inclusion as a criterion for the classification of SLE.

Antineuronal antibodies and electroneurophysiological studies in pediatric patients with neuropsychiatric systemic lupus erythematosus

Neuropsychiatric systemic lupus erythematosus (NPSLE) is one of the most difficult manifestations of lupus to diagnose. Measurement of serum brain autoantibodies and assessment of cognitive function by electroneurophysiological studies (electroencephalogram (EEG) and P300) have contributed to an earlier and a more specific diagnosis of NPSLE. Thus, we were stimulated to assess the value of serum antineuronal antibodies and electroneurophysiological studies in diagnosis and early prediction of NPSLE. To investigate this, assessment of serum antineuronal antibodies and cognitive function (clinically and by electroneurophysiological studies) was done in 30 lupus patients [14 (46.7%) with and 16 (53.3%) without clinical evidence of NPSLE] in comparison with 30 healthy matched subjects. Patients without clinical evidence of NPSLE were followed-up clinically by monthly neuropsychiatric evaluation for 18 months. Seropositivity for antineuronal antibodies and abnormalities of EEG and P300 (prolonged latency and/or low amplitude) were found in 60%, 50% and 70%, respectively of lupus patients. During follow-up, 8 out of the 16 patients without clinical evidence of NPSLE developed such evidence [six (75%) had antineuronal seropositivity, five (62.5%) had abnormal EEG, six (75%) had P300 abnormalities and all had at least one abnormal result of these parameters at the time of initial evaluation before clinical presentation of NPSLE]. In conclusion, serum antineuronal antibodies and electroneurophysiological studies may be reliable parameters for diagnosis and early prediction of NPSLE, especially when combined together, before clinical manifestations ensue. Further studies on a large scale are warranted to evaluate the predictive value of these parameters in NPSLE.

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.

Autoimmune pathology accounts for common manifestations in a wide range of neuro-psychiatric disorders: the olfactory and immune system interrelationship

Smell has traditionally been considered a less important sense when compared to sight or hearing, but recent research has unraveled important features inherent to the sense of smell. Once considered just a chemical sensor for sampling the environment, data from animal models and human studies currently imply numerous and complex effects of smell on behavior, mood, and on the immune response. In this review we discuss a possible inter-relationship between olfactory impairment, autoimmunity and neurological/psychiatric symptoms in several diseases affecting the central nervous system (CNS) such as Parkinson, Alzheimer's disease, autism, schizophrenia, multiple sclerosis and neuropsychiatric lupus erythematosus. We suggest that common manifestations are not mere coincidences. Current data from animal models show that neuropsychiatric manifestations are intimately associated with smell impairment, and autoimmune dysregulation, via autoantibodies (anti-NMDAR, anti-ribosomal P) or other mechanisms. From clues of pathological manifestations, we propose a novel approach to the understanding of the interactions between the CNS, the smell and the immune system.

Limited reliability of the indirect immunofluorescence technique for the detection of anti-Rib-P antibodies

Introduction

Autoantibodies to the ribosomal P proteins represent a highly specific marker for the diagnosis of systemic lupus erythematosus, where they have been associated with certain clinical manifestations. Historically, autoantibodies against ribosomal P proteins have been detected by indirect immunofluorescence, immunodiffusion, immunoblot, and other immunoassays. More recently, enzyme-linked immunosorbent assays and line and addressable laser bead immunoassays have become more widely used. The primary goal of this study was to determine the sensitivity of indirect immunofluorescence using conventional HEp-2 substrates in the detection of sera with ribosomal P antibodies as detected by other immunoassays.

Methods

Anti-ribosomal P-positive sera (n = 345) as detected by an addressable laser bead immunoassay were collected between 2003 and 2007 and analysed by indirect immunofluorescence. Furthermore, 51 anti-ribosomal P-positive samples from an unselected systemic lupus erythematosus cohort (n = 100) and the Centers for Disease Control and Prevention (CDC) anti-nuclear antibody (ANA) reference sera were tested for anti-ribosomal P reactivity.

Results

In the cohort of 345 anti-ribosomal P-positive samples identified by addressable laser bead immunoassay, a low sensitivity (<30%) of indirect immunofluorescence on HEp-2 cell substrates was observed. Although the degree of sensitivity varied among different manufacturers, all immunofluorescence substrates exhibited limited sensitivity and false-negative results were not restricted to samples with low anti-ribosomal P titers. Even the anti-ribosomal P reactivity of CDC ANA reference serum number 12 was not clearly predictable by indirect immunofluorescence. Comparison of five different methods for the detection of anti-ribosomal P found moderate qualitative agreements.

Conclusions

Based on our data, we conclude that indirect immunofluorescence on HEp-2 cells is not a reliable screening test for the prediction of ribosomal P antibodies. As this method is widely used as a first-line screening test for anti-nuclear and other autoantibodies, special considerations for the detection of ribosomal P antibodies are needed. As with many other autoantibodies, further effort is required for the standardisation of ribosomal P immunoassays.

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.

Autoantibodies to intracellular autoantigens and their B-cell epitopes: molecular probes to study the autoimmune response

A common laboratory finding in systemic autoimmune diseases is the presence of autoantibodies against intracellular autoantigens. Although their pathogenesis is not fully understood, autoantibodies are important tools for establishing diagnosis, classification, and prognosis of autoimmune diseases. Autoantibodies mainly target multicomponent complexes containing both protein antigens and (ribo)-nucleic acid(s), such as the spliceosome or Ro/La RNPs. In this review, we address the main characteristics and the clinical value of the main autoantibody types with respect to their disease association, and we describe the corresponding autoantigens, their biologic function, and their B-cell antigenic determinants (epitopes). The structural characteristics and clinical associations of these epitopes, and their utility as tools to investigate the autoimmune response, are discussed in detail. New insights into the pathogenetic role of epitopes in systemic autoimmunity are also examined. In this regard, using the defined structures of the B-cell antigenic epitopes, complementary epitopes can be designed according to the "molecular recognition" theory. These complementary epitopes can be used as probes to study pathogenetic and immunoregulatory aspects of the anti-idiotypic response. The origin of humoral autoimmunity and the spreading of the epitopes in systemic lupus erythematosus are also discussed. Finally, the ability of post-translational modifications to induce autoreactive immune attack via the generation of neo-epitopes is summarized.

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.

Management of neuropsychiatric lupus

Nervous system disease in systemic lupus erythematosus (SLE) is manifested by a wide variety of clinical manifestations. Despite the development of a universal classification for neuropsychiatric (NP) lupus in 1999, there continues to be considerable variability in the reported prevalence of NP syndromes between different lupus cohorts. Due to the lack of specificity of individual NP manifestations, non-SLE causes such as complications of therapy and co-morbidities must be considered in advance of attributing the event to one or more primary immunopathogenic mechanisms. These include intracranial microangiopathy, autoantibodies to neuronal and non-neuronal antigens, and the generation of proinflammatory cytokines and mediators. The diagnosis of NP-SLE remains largely one of exclusion and is approached in individual patients by thorough clinical evaluation, supported when necessary by autoantibody profiles, diagnostic imaging, electrophysiologic studies and objective assessment of cognitive performance. Given the diversity in clinical manifestations, the management is tailored to the specific needs of individual patients. In the absence of controlled studies, the use of symptomatic therapies, immunosuppressives, anticoagulants and non-pharmacologic interventions is supported by case series and clinical experience.

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.

Humoral Antigenic Targets of the Ribosomal P0 Lupus Autoantigen Are Not Limited to the Carboxyl Region

Autoantibodies binding the ribosomal P phosphoproteins are highly specific for systemic lupus erythematosus (SLE) and can be found in precipitating levels in approximately 15% of these patients. Anti-ribosomal P antibodies are directed against three proteins, and the primary autoimmune target of this response has been described as a common 22-amino acid sequence. Sera from 31 anti-ribosomal P immunodiffusion-positive SLE patients were tested for C-terminal P-peptide reactivity by ELISA. Sera from three patients (9.7%) were negative for the peptide ELISA, despite having anti-ribosomal P by immunodiffusion and Western blot. In addition, inhibition experiments showed that the common P-peptide response accounts for a variable amount of anti-ribosomal P0 reactivity (52-89% of the response dependent upon the patient serum). Based upon these findings, fine-specificity sequential humoral epitope mapping of ribosomal P0 was performed. Several common sequential antigenic targets were defined dispersed throughout the molecule. The most commonly targeted epitopes included RDMLLANKVPAAARA (amino acids 99-113, 11 of 12 patients reactive) and QALGITTKISRGT (amino acids 139-151, 9 of 12 patients reactive). This study confirms that the P22 ribosomal peptide is commonly targeted in SLE and accounts for a variable percentage of the anti-ribosomal P response. Additional anti-ribosomal P humoral epitopes are described.