Diagnosis of neuropsychiatric systemic lupus erythematosus by label-free serum microsphere-coupled SERS fingerprints with machine learning.

Surface-enhanced Raman spectroscopy (SERS) is a powerful optical technique for non-invasive and label-free bioanalysis of liquid biopsy, facilitating to diagnosis of potential diseases. Neuropsychiatric systemic lupus erythematosus (NPSLE) is one of the subgroups of systemic lupus erythematosus (SLE) with serious manifestations for a high mortality rate. Unfortunately, lack of well-established gold standards results in the clinical diagnosis of NPSLE being a challenge so far. Here we develop a novel Raman fingerprinting machine learning (ML-) assisted diagnostic method. The microsphere-coupled SERS (McSERS) substrates are employed to acquire Raman spectra for analysis via convolutional neural network (CNN). The McSERS substrates demonstrate better performance to distinguish the Raman spectra from serums between SLE and NPSLE, attributed to the boosted signal-to-noise ratio of Raman intensities due to the multiple optical regulation in microspheres and AuNPs. Eight statistically-significant (p-value <0.05) Raman shifts are identified, for the first time, as the characteristic spectral markers. The classification model established by CNN algorithm demonstrates 95.0% in accuracy, 95.9% in sensitivity, and 93.5% in specificity for NPSLE diagnosis. The present work paves a new way achieving clinical label-free serum diagnosis of rheumatic diseases by enhanced Raman fingerprints with machine learning.

Correlation Between B-Cell Activating Factor of the Tumor Necrosis Factor Family Level in Serum and Immune Inflammation in Patients with Neuropsychiatric Systemic Lupus Erythematosus and its Clinical Value.

OBJECTIVE: Neuropsychiatric systemic lupus erythematosus (NPSLE) is a form of SLE associated with severe NP syndromes causing mortality and morbidity. Respecting the fundamental of BAFF in NPSLE pathophysiology, we investigated its clinical value. METHODS: Totally 105 NPSLE and 101 SLE cases without NPSLE (non-NPSLE, control) were included. Serum BAFF/TNF-α/IL-6/IL-10 levels were measured using ELISA kits. T lymphocytes were detected by flow cytometry. The independent influencing factors for NPSLE, and the auxiliary diagnostic efficacy and the ability of BAFF levels to predict adverse prognosis of NPSLE patients were analyzed by multiple factor logistic regression, and ROC curve and survival curve. RESULTS: In NPSLE patients, serum BAFF level was increased and positively correlated with SLEDAI-2k, serum proinflammatory cytokines, while negatively correlated with CD4+T/CD8+T cells, and anti-inflammatory cytokine. High serum BAFF protein level was associated with a higher risk of developing NPSLE. The AUC of serum BAFF > 301.7 assisting in NPSLE diagnosis was 0.8196. Furthermore, high levels of serum BAFF were associated with a higher risk of adverse outcomes in NPSLE patients. . CONCLUSION: Serum BAFF level in NPSLE patients was correlated with lymphocytes and high serum BAFF protein level could assist in diagnosis and to predict adverse outcomes in NPSLE patients.

Is serum TWEAK a useful biomarker of neuropsychiatric systemic lupus erythematosus?

The aim of this study was to determine the role of the tumor necrosis factor like weak inducer of apoptosis (TWEAK) as a serum biomarker of neuropsychiatric involvement in systemic lupus erythematosus (NPSLE). Levels of TWEAK levels were measured in sera of 92 patients with systemic lupus erythematosus (SLE), including 28 patients with neuropsychiatric lupus, and in 59 healthy controls using ELISA. All SLE patients underwent rheumatological, neurological and psychiatric assessment. We found no significant differences in TWEAK levels, between SLE patients and the healthy controls (p=0.2411). Similarly, no difference was observed between subgroup of NPSLE and healthy controls (p=0.7658). The mean SLE disease activity (SLEDAI) was 13.25. No correlations between TWEAK levels with disease activity (SLEDAI, r=0.2113, p=0.2805) or the most common NPSLE manifestations such as headache (r=0.2079), seizures (r=0.1101), cerebrovascular disease (r= 0.2347), cognitive dysfunction (r=0.1597) and anxiety (r=0.1397) were observed. Our data do not support the use of serum TWEAK as a discriminating biomarker for NPSLE. The role of the TWEAK in NPSLE remains to be investigated.

Role of serum autoantibodies in blood brain barrier damages in neuropsychiatric systemic lupus erythematosus.

OBJECTIVES: The present study was carried out to elucidate the roles of serum autoantibodies in the development of blood-brain barrier (BBB) damages in neuropsychiatric systemic lupus erythematosus (NPSLE). METHODS: Paired serum and CSF samples were obtained from 101 SLE patients when they presented active neuropsychiatric manifestations (69 patients with diffuse psychiatric/neuropsychological syndromes [diffuse NPSLE] and 32 patients with neurologic syndromes or peripheral neuropathy [focal NPSLE]). IgG anti-NR2 subunit of NMDA receptor (anti-NR2), anti-Sm, anti-ribosomal P and IgG anti-cardiolipin in sera and albumin in CSF and sera were measured by ELISA. Blood-brain barrier (BBB) function was evaluated by Q albumin (CSF/serum albumin quotient x 1,000). RESULTS: Q albumin was significantly higher in acute confusional state (ACS) than in non-ACS diffuse NPSLE (anxiety disorder, cognitive dysfunction, mood disorder and psychosis) or in focal NPSLE. Anti-Sm, but not anti-NR2, anti-P or anticardiolipin, was significantly elevated in ACS compared with the other 2 groups of NPSLE, although serum anti-NR2 was significantly higher in ACS than that in focal NPSLE. Multiple regression analysis confirmed the significant contribution of anti-Sm (p=0.0040), but not anti-NR2 (p=0.5023), anti-P (p=0.2651), or anti-cardiolipin (p=0.6769) in the elevation of Q albumin. CONCLUSIONS: The data demonstrate that serum anti-Sm antibodies play a most important role in the disruption of BBB in NPSLE.

Evaluation of blood-brain barrier function by quotient alpha2 macroglobulin and its relationship with interleukin-6 and complement component 3 levels in neuropsychiatric systemic lupus erythematosus.

Although quotient of alpha2 macroglobulin (Qα2MG) was previously reported to be useful for the evaluation of blood-brain barrier (BBB) function, it is not commonly used. We therefore evaluated BBB function among the various subsets of neuropsychiatric systemic lupus erythematosus (NPSLE) using quotient Q α2MG. Furthermore, we determined the correlation between Q α2MG and cerebrospinal (CSF) interleukin (IL)-6 level and quotient complement component 3 (Q C3). To determine intrathecal production of C3, the C3 index (Q C3/Q α2MG) was also calculated. Fifty-six patients with SLE were included in this study. Of these, 48 were diagnosed with NPSLE, consisting of 30 diffuse NPSLE patients (acute confusional state (ACS): n = 14, non-ACS: n = 16) and 18 patients with focal NPSLE. CSF IL-6 concentration, and paired serum and CSF levels of α2MG and C3, were measured by enzyme-linked immuno solvent assay (ELISA). The Q α2MG, Q C3, and C3 index were then calculated. Q α2MG, Q C3, and IL-6 concentrations in the CSF were significantly elevated in NPSLE compared with non-NPSLE. Among the subsets of NPSLE, significant increases in Q α2MG, CSF IL-6, and Q C3 were observed in ACS compared with non-ACS or focal NPSLE. There was a positive correlation between CSF IL-6 level and Q α2MG, as well as between Q C3 and Q α2MG, in diffuse NPSLE. There were no significant differences in C3 index between NPSLE and non-NPSLE, as well as among the subgroups of NPSLE. Our study suggests that BBB disruption is present in ACS, and elevated levels of IL-6 and C3 in CSF in diffuse NPSLE, especially in ACS, might result from their entry to the CSF from the systemic circulation through the damaged BBB, as well as increased intrathecal production. Furthermore, Q α2MG might be useful for the evaluation of BBB integrity.

Autoantibodies to NR2A Peptide of the Glutamate/NMDA Receptor in Patients with Seizure Disorders in Neuropsychiatric Systemic Lupus Erythematosus.

Objective. Seizure disorders are one of the most disabling, life-threatening, and the least understood syndromes associated with neuropsychiatric SLE (NPSLE). N-Methyl-D-aspartate (NMDA) receptors are a subgroup of the glutamate receptor family, whose NR2A subunit was found on neuronal cells (anti-NR2A) in NPSLE patients with different types of epilepsy. The present study was conducted to determine the serum levels of anti-NR2A antibodies in a large group of SLE patients, to investigate the possible correlation between the presence of the NR2A specific antibodies and NPSLE-related seizure disorders. Methods and Results. The study population consisted of 107 SLE patients and 43 age- and sex-matched healthy controls. 73 SLE patients had active disease. 36 of these had NPSLE. NMDA levels were measured by ELISA. Clinical and serological parameters were assessed according to routine procedures. The levels of anti-NR2A antibodies were significantly higher in NPSLE patients, compared with non-NPSLE patients and healthy controls. Furthermore, the levels of NPSLE in patients with seizure disorders were shown to be higher than in those with cognitive dysfunction and other CNS symptoms, however, without significance. Increase in serum anti-NR2A antibodies levels correlated to anti-dsDNA antibody and SLEDAI as well as complement levels. Conclusion. We suggest that anti-NR2A antibodies play a role in the pathogenesis of NPSLE with seizure disorders.

Brain MRI in patients with acute confusional state of diffuse psychiatric/neuropsychological syndromes in systemic lupus erythematosus.

OBJECTIVE: The objective of this study is to explore the characteristics of brain MRI abnormalities in acute confusional state (ACS) in neuropsychiatric systemic lupus erythematosus (NPSLE). METHODS: Thirty-six patients with ACS admitted to our institutions from 1992 to 2015 were exhaustively enrolled. Their medical charts and brain MRI scans were reviewed. RESULTS: Eighteen of 36 ACS patients had MRI abnormalities, mostly high-intensity lesions of various sizes in the cerebral white matter. MRI abnormalities improved after treatment in 12 of 14 patients in follow-up studies. MRI abnormalities were not correlated with ages at the onset of ACS, disease durations of SLE, the presence of anti-DNA, anti-phospholipid or anti-ribosomal P antibodies, or IL-6 levels in sera or cerebrospinal fluid. Notably, MRI abnormalities were significantly associated with the presence of serum anti-Sm antibodies (p = 0.0067). Finally, eight of the 18 patients with MRI abnormalities, but none of the other 18 patients without MRI abnormalities, died from active SLE. Thus, MRI abnormalities significantly increased the mortality in ACS (p = 0.0013, HR =10.36 [95% CI: 2.487-43.19]). CONCLUSION: These results demonstrate that patients with ACS with MRI abnormalities have more severe diseases, resulting in poorer prognoses. The data also indicate that anti-Sm is involved in the development of MRI abnormalities in ACS.

IL-6, IL-8, IP-10, MCP-1 and G-CSF are significantly increased in cerebrospinal fluid but not in sera of patients with central neuropsychiatric lupus erythematosus.

OBJECTIVE: To determine whether the intrathecal concentrations of cytokines/chemokines are associated with, or influenced by, serum concentrations in patients with central neuropsychiatric systemic lupus erythematosus (NPSLE), and to ascertain whether the increased production of cytokines/chemokines intrathecally relative to serum levels is associated with the presence of central NPSLE. METHODS: 52 SLE patients (30 with central NPSLE and 22 with non-NPSLE), for whom the CSF and serum samples were obtained at the same time, were enrolled. 27 kinds of cytokine/chemokine concentrations other than IFN-α in the cerebrospinal fluid (CSF) and serum samples were measured by Bio-Plex Pro Assays. IFN-α concentration and anti-ribosomal P protein antibody (anti-P) titres in CSF and serum samples were measured by ELISA. RESULTS: The mean concentrations of IL-6, IL-8, IP-10, MCP-1, G-CSF and GM-CSF were higher in the CSF than in the sera, respectively, while the mean concentrations of other 22 cytokines/chemokines, including RANTES and IFN-α, in the CSF were much lower than those in the sera, respectively. Furthermore, the concentrations of IL-6, IL-8, IP-10, MCP-1 and G-CSF in the CSF of the 30 patients with NPSLE were significantly higher than in the 22 patients with non-NPSLE (p = 6.82 × 10(-5), p = 0.00037, p = 0.0028, p = 0.00065, and p = 0.0001, respectively), while the concentration of GM-CSF in the CSF of the 30 patients with NPSLE was not significantly higher than in the 22 patients with non-NPSLE. Most importantly, the largest difference occurred in CSF IL-6 concentrations. A significant positive correlation between CSF anti-P titres and serum anti-P titres in 52 patients with SLE (r = 0.6316, p = 6.44 × 10(-6)) was found, while no significant positive correlation was observed between CSF levels and serum levels of each cytokine/chemokine in the 52 SLE patients. CONCLUSION: In central NPSLE the production of IL-6, IL-8, IP-10, MCP-1 and G-CSF might take place in the central nervous system (CNS). These increased CSF cytokines/chemokines along with anti-P might have a prerequisite role in the pathogenesis of central NPSLE.

Utility of TWEAK to assess neuropsychiatric disease activity in systemic lupus erhytematosus.

OBJECTIVE: The purpose of this study was to assess the utility of tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) in serum and cerebrospinal fluid (CSF) as a biomarker in neuropsychiatric systemic lupus erythematosus (NPSLE). METHODS: Thirty three NPSLE patients were evaluated at hospitalization and six months later. As controls, five SLE patients with septic meningitis, 51 hospitalized SLE patients without a history of neuropsychiatric (NP) manifestations and without infections, 16 SLE patients without NP manifestations (surgical-SLE), four patients with primary neuropsychiatric disorders, and 25 patients with non-autoimmune diseases were also studied. Serum and CSF samples were drawn at hospitalization, except non-NPSLE patients, in whom only serum was studied, and six months later in 19 NPSLE and 27 non-NPSLE patients. Serum and CSF TWEAK levels were measured by ELISA; values are expressed in pg/mL. RESULTS: The mean ± SD age of NPSLE patients was 31 ± 13.1 years, which was similar across study groups (p = 0.54). TWEAK levels in serum were not different across the study groups. In CSF, TWEAK levels were higher in NPSLE, surgical-SLE and primary neuropsychiatric groups than in non-autoimmune patients: median (IQR) 159.2 (94.1-374.9), 172.3 (125.3-421.9), 371.3 (143-543) vs. 122.1 (76.1-212.4), respectively; all p < 0.05. Six months later, when the neuropsychiatric manifestations were clinically in remission, serum or CSF TWEAK did not vary from baseline in NPSLE patients. CONCLUSIONS: TWEAK levels are slightly elevated in CSF in SLE patients compared with non-autoimmune controls, irrespective of the presence of NP manifestations. TWEAK levels in serum and CSF do not seem to be a useful biomarker of CNS involvement in SLE.

Two-step chromatography purification of IgGs possessing sialidase activity from human blood serum.

Sialation of cell surface is known to be tightly connected with tumorigenicity, invasiveness, metastatic potential and clearance of aged cells, while sialation of immunoglobulin G (IgG) molecules determines their anti-inflammatory properties. Recently, we have found for the first time IgG-antibodies possessing sialidase-like activity (sialylic abzyme) in blood serum of multiple myeloma and systemic lupus erythematosis patients. This abzyme was detected in a pool of IgGs purified by a typical procedure including immunoglobulin's precipitation with ammonium sulfate and following chromatography on protein G-Sepharose column. Here we describe a novel matrix for affinity purification of sialylic abzyme that is based on using bovine submandibular gland mucin conjugated to Sepharose matrix (mucin-Sepharose). This matrix preferentially binds sialidase-like IgGs from a pool of sialidase-active fraction of proteins precipitated with 50% ammonium sulfate from blood serum of the systemic lupus erythematosis patients. That allowed us to develop a new scheme of double-step chromatography purification of sialidase-like IgGs from human blood serum.

Association of cerebrospinal fluid anti-Sm antibodies with acute confusional state in systemic lupus erythematosus.

INTRODUCTION: Neuropsychiatric manifestation in systemic lupus erythematosus (NPSLE) is one of the most serious complications of the disease. Previous studies revealed the strong association between serum anti-Sm and organic brain syndrome, consisting mainly of acute confusional state (ACS) of diffuse psychiatric/neuropsychological syndromes (diffuse NPSLE). However, the precise mechanism by which anti-Sm causes diffuse NPSLE remains unclear. Of note, recent studies demonstrated that anti-U1 RNP antibodies (anti-RNP) in cerebrospinal fluid (CSF) are associated with NPSLE. The present study was designed to explore the association of anti-Sm antibodies in CSF with NPSLE. METHODS: Paired serum and CSF specimens were obtained from 72 patients with NPSLE (49 with diffuse NPSLE, 23 with neurological syndromes or peripheral neuropathy (focal NPSLE) and from 22 control patients with non-SLE neurological diseases. Sera were also obtained from 41 patients with active SLE without neuropsychiatric manifestations (non-NPSLE). Anti-Sm and anti-RNP were measured by enzyme-linked immunosorbent assay (ELISA). Blood-brain barrier (BBB) function and intrathecal anti-Sm production were evaluated by Q albumin and CSF anti-Sm index, respectively. Binding of anti-Sm to neuroblastoma cell lines SK-N-MC and Neuro2a was examined by flow cytometry and by cell ELISA. RESULTS: Anti-Sm and anti-RNP in CSF and sera were elevated in NPSLE compared with non-SLE control. CSF anti-Sm, but not CSF anti-RNP, was significantly elevated in ACS compared with non-ACS diffuse NPSLE or with focal NPSLE. By contrast, there were no significant differences in serum anti-Sm or anti-RNP among subsets of NPSLE and non-NPSLE. Whereas there were no significant differences in CSF anti-Sm index, Q albumin was elevated in ACS compared with non-ACS or with focal NPSLE. Notably, CSF anti-Sm was correlated with Q albumin (r = 0.2373, P = 0.0447) or with serum anti-Sm (r = 0.7185, P <0.0001) in 72 patients with NPSLE. Finally, monoclonal anti-Sm and purified human anti-Sm bound to the surface of SK-N-MC and Neuro2a. CONCLUSIONS: These results demonstrate that the elevation of CSF anti-Sm through transudation from systemic circulation due to damaged BBB plays a critical role in the pathogenesis of ACS. More importantly, the data indicate that anti-Sm is yet another autoantibody with presumed neural toxicity, but might not be the last.

Diagnosis and early detection of CNS-SLE in MRL/lpr mice using peptide microarrays.

BACKGROUND: An accurate method that can diagnose and predict lupus and its neuropsychiatric manifestations is essential since currently there are no reliable methods. Autoantibodies to a varied panel of antigens in the body are characteristic of lupus. In this study we investigated whether serum autoantibody binding patterns on random-sequence peptide microarrays (immunosignaturing) can be used for diagnosing and predicting the onset of lupus and its central nervous system (CNS) manifestations. We also tested the techniques for identifying potentially pathogenic autoantibodies in CNS-Lupus. We used the well-characterized MRL/lpr lupus animal model in two studies as a first step to develop and evaluate future studies in humans. RESULTS: In study one we identified possible diagnostic peptides for both lupus and altered behavior in the forced swim test. When comparing the results of study one to that of study two (carried out in a similar manner), we further identified potential peptides that may be diagnostic and predictive of both lupus and altered behavior in the forced swim test. We also characterized five potentially pathogenic brain-reactive autoantibodies, as well as suggested possible brain targets. CONCLUSIONS: These results indicate that immunosignaturing could predict and diagnose lupus and its CNS manifestations. It can also be used to characterize pathogenic autoantibodies, which may help to better understand the underlying mechanisms of CNS-Lupus.

Development of systemic lupus erythematosus in a male-to-female transsexual: the role of sex hormones revisited.

Systemic lupus erythematosus (SLE) predominantly affects women of childbearing age. The infrequency of SLE in men and disease onset in prepubertal or postmenopausal women suggests a role of estrogen in the predisposition to the disease. Patients with hypergonadotrophic hypogonadism are prone to the development of SLE, and the use of exogenous estrogens in women increases the relative risk of SLE onset and disease flares. These observations provide indirect evidence for an opposite role of estrogens and androgens in the pathogenesis of SLE. We report on a male-to-female transsexual who developed SLE 20 years after sex-reassignment surgery and prolonged estrogen therapy. The role of sex hormones in SLE is revisited.

Association of serum B cell activating factor from the tumour necrosis factor family (BAFF) and a proliferation-inducing ligand (APRIL) with central nervous system and renal disease in systemic lupus erythematosus.

INTRODUCTION: The objective of this study is to determine whether serum concentrations of B cell activating factor from the tumour necrosis factor family (BAFF) and/or a proliferation-inducing ligand (APRIL) are associated with clinical manifestations of systemic lupus erythematosus (SLE). METHODS: BAFF and APRIL concentrations were quantified using a commercial ELISA in serum samples obtained at the time of clinical assessment in 98 patients, and on 245 samples from 75 of these patients followed prospectively. RESULTS: Serum BAFF was significantly increased, and APRIL decreased, in patients with either renal or central nervous system (CNS) lupus. In contrast, in cross-sectional analysis, there was no correlation between disease activity (SLEDAI-2k) and serum BAFF or APRIL. In longitudinal follow-up, there was no association between changes in serum BAFF or APRIL and changes in SLEDAI-2k, or between baseline serum BAFF or APRIL and subsequent changes in SLEDAI-2k. However, between-visit changes in BAFF were significantly different in patients with increases in SLEDAI-2k ≥ 4, compared to patients whose SLEDAI-2k did not change. CONCLUSIONS: Although neither serum BAFF nor APRIL correlated with disease activity in the overall population, elevated serum BAFF and reduced APRIL may be markers of renal and CNS disease in SLE patients.

Serum antibodies against the 70k polypeptides of the U1 ribonucleoprotein complex are associated with psychiatric syndromes in systemic lupus erythematosus: a retrospective study.

OBJECTIVES: We assessed the association between serum autoantibodies against the 70-kDa polypeptide of the U1-ribonucleoprotein (RNP) complex (U1-70k) and the central nervous system (CNS) syndromes in systemic lupus erythematosus (SLE) patients. METHODS: We studied 106 hospitalized patients with active SLE, comparing those with (n = 32) and without (n = 74) CNS syndromes. CNS syndromes were further classified into neurologic (n = 21) and psychiatric (n = 15) disorders. Immunoglobulin G (IgG) anti-U1-70k antibodies were measured by enzyme-linked immunosorbent assay (ELISA) using recombinant antigens. IgG antibodies against whole U1-RNP were measured using commercial ELISA kits. RESULTS: Although there was no significant difference in the levels of serum anti-U1-70k antibodies in SLE patients with or without CNS syndromes (p = 0.83), the levels were significantly elevated in SLE patients compared with patients without psychiatric syndromes (p = 0.030). In contrast, no significant difference was observed in the levels of serum anti-U1-RNP antibodies in SLE patients with or without psychiatric syndromes (p = 0.555). CONCLUSIONS: These results indicate that serum anti-U1-70k antibodies are associated with psychiatric syndromes in SLE but that they are not associated with CNS syndromes as a whole or with neurologic syndromes. The anti-U1-70k antibodies might be involved in the pathological mechanisms of psychiatric syndromes in SLE.

Cerebrospinal fluid levels of a proliferation-inducing ligand (APRIL) are increased in patients with neuropsychiatric systemic lupus erythematosus.

OBJECTIVES: A proliferation-inducing ligand (APRIL) and B-cell activation factor (BAFF) are B-cell stimulation and survival molecules. We have investigated whether APRIL and/or BAFF activity is enhanced in the systemic and/or intrathechal compartment of patients with neuropsychiatric systemic lupus erythematosus (NPSLE). In particular, the association between fatigue and APRIL/BAFF activity was investigated. METHODS: Twenty-eight NPSLE patients were evaluated clinically, with sampling of cerebrospinal fluid (CSF) and blood, and magnetic resonance imaging (MRI). CSF and blood samples from 13 multiple sclerosis (MS) patients and 17 patients with other neurological diseases (OND) were used as controls. Protein levels of BAFF and APRIL were quantified in CSF and plasma, mRNA expression levels of BAFF and APRIL were determined in peripheral blood (PBMC) and CSF mononuclear cells (CSF-MC). The Fatigue Severity Scale (FSS) was used to quantify the degree of fatigue. RESULTS: NPSLE patients had higher levels of APRIL in CSF as compared to OND (p < 0.01). No corresponding increase in APRIL mRNA levels was detected in CSF-MC. BAFF levels in plasma were higher in NPSLE than in OND (p < 0.001). BAFF mRNA expression in PBMC was also higher in NPSLE patients than in controls (p < 0.05). FSS scores in patients with NPSLE correlated significantly with APRIL levels in CSF. CONCLUSIONS: Protein levels of APRIL in CSF were increased in NPSLE as compared to OND. Moreover, there was a positive correlation between CSF APRIL levels and fatigue. Our results suggest that APRIL and possibly also BAFF may be involved in the pathogenesis of NPSLE and in SLE-related fatigue.

Anti-NR2A antibody as a predictor for neuropsychiatric systemic lupus erythematosus.

OBJECTIVE: The aim of this study is to establish a detection method for anti-N-methyl-d-aspartate receptor subunit 2A (NR2A) antibody and to evaluate the relationship between anti-NR2A antibody and various organ involvement in SLE. METHODS: Serum anti-NR2A antibody was measured by ELISA using a peptide with a core of either DWEYS or DWDYS as autoantigen. Additionally, clinical characteristics were compared between 27 anti-NR2A antibody-positive (P group) and 80 antibody-negative (N group) SLE patients using DWDYS peptide. RESULTS: The optical density (OD) values of anti-NR2A antibody using DWDYS and DWEYS peptides correlated significantly (r = 0.94, P < 0.0001). The median OD value was significantly higher (P < 0.0001) with DWDYS. Additionally, the SLEDAI was significantly higher (P = 0.023) in the P group. The frequency of neuropsychiatric SLE (NPSLE) was significantly higher (P = 0.0002) in the P group, although the frequencies of serositis and nephritis were not statistically significant. Significant correlations were found between anti-NR2A antibody and leucocyte count (r(s) = -0.31, P = 0.001) and haemoglobin (r(s) = -0.42, P < 0.0001), although no correlation was found between anti-NR2A antibody and the titre of anti-dsDNA antibody. NPSLE was the most significant independent variable (P = 0.0008) associated with anti-NR2A antibody positivity, as estimated by multiple linear regression analysis. CONCLUSION: Serum anti-NR2A antibody can be associated with the complication of NPSLE and may indicate the involvement of non-nervous tissue. The use of peptides that include DWDYS is preferable to detect anti-NR2A antibody in ELISA.

Identification of autoantigens specific for systemic lupus erythematosus with central nervous system involvement.

Using proteomic analysis, we identified candidate autoantigens specific for central nervous system (CNS) involvement in systemic lupus erythematosus (SLE). Proteins, extracted from cultured human neuroblastoma cells, were separated both by SDS-PAGE (1-DE) and two-dimensional electrophoresis (2-DE), and transferred to membranes. Western blot analysis was performed using serum samples from 30 SLE patients with CNS involvement (CNS-Lupus) and from 30 SLE patients without CNS involvement (non-CNS-SLE). The detected autoantigens were identified using MALDI-TOF/TOF MS. On the 1-DE Western blot, we detected 32 antigenic bands in the serum samples from the CNS-Lupus patients. Among them, four bands were detected significantly more frequently in the CNS-Lupus patients than in the non-CNS-SLE patients. Three bands were detected in four or more of the CNS-Lupus patients but in only one or none of the non-CNS-SLE patients. We thus selected these seven bands for the next investigations. Next, we detected protein spots corresponding to the selected seven bands by 2-DE Western blot and identified four proteins. They are peroxiredoxin-4, ubiquitin carboxyl-terminal hydrolase isozyme L1, splicing factor arginine/serine-rich 3, and histone H2A type 1. These four candidate autoantigens for the anti-neuronal cell antibodies would be a useful marker for CNS-Lupus.

Potent induction of IFN-alpha and chemokines by autoantibodies in the cerebrospinal fluid of patients with neuropsychiatric lupus.

Neuropsychiatric disease in systemic lupus erythematosus (NPSLE) is a poorly understood, but potentially fatal, disease manifestation. A pathogenetic role for autoantibodies is suspected, but the mechanism is unclear. Since immune complexes in SLE can stimulate IFN-alpha and there is strong evidence in humans and in mice that IFN-alpha can cause neuropsychiatric manifestations, we asked whether NPSLE patient serum and/or cerebrospinal fluid (CSF) contain abnormally high IFN-alpha-inducing activity. In a bioassay containing plasmacytoid dendritic cells and a source of Ag, NPSLE CSF induced significantly higher IFN-alpha compared with CSF from patients with multiple sclerosis or other autoimmune disease controls. When normalized for IgG concentration, NPSLE CSF was 800-fold more potent at inducing IFN-alpha compared with paired serum due to inhibitors present in serum. Analysis of Ig-deficient patient serum, depletion of IgG from normal serum, as well as addition of purified IgG to NPSLE CSF and serum in the bioassays revealed that one inhibitor was contained within the IgG fraction itself. In addition to IFN-alpha, immune complexes formed by CSF autoantibodies produced significantly increased levels of IFN-gamma-inducible protein 10 (IP-10/CXCL), IL-8, and MCP-1, all of which have been reported to be elevated in CSF from NPSLE patients. Taken together, these findings are consistent with a two-step model of NPSLE whereby CSF autoantibodies bind to Ags released by neurocytotoxic Abs or other brain cell injury, and the resulting immune complexes stimulate IFN-alpha and proinflammatory cytokines and chemokines.

Raised intrathecal levels of APRIL and BAFF in patients with systemic lupus erythematosus: relationship to neuropsychiatric symptoms.

INTRODUCTION: The tumour necrosis factor (TNF) family ligands BAFF (B-cell activating factor of TNF family) and APRIL (a proliferation-inducing ligand) are essential for B-cell survival and function. Elevated serum levels of BAFF and APRIL have been reported earlier in patients with systemic lupus erythematosus (SLE). Since autoantibody formation in the central nervous system (CNS) is a distinct feature of neuropsychiatric SLE (NPSLE), we have investigated whether NPSLE is associated with an enhanced intrathecal production of APRIL and BAFF. METHODS: Levels of BAFF and APRIL in cerebrospinal fluid (CSF) and serum from healthy controls, SLE patients without CNS involvement, and patients with NPSLE were determined by enzyme-linked immunosorbent assay. Interleukin-6 (IL-6) levels were determined by an IL-6-specific bioassay. RESULTS: SLE patients had levels of APRIL in CSF that were more than 20-fold higher and levels of BAFF in CSF that were more than 200-fold higher than those of healthy controls. Separate analyses of SLE patients with and without CNS involvement revealed that NPSLE patients had enhanced levels of APRIL in CSF. BAFF and APRIL were likely produced locally in the CNS as CSF and serum levels did not correlate. Moreover, CSF levels of APRIL correlated with BAFF but not with IL-6, suggesting that APRIL and BAFF in the CNS are regulated together but that they are produced independently of IL-6. CONCLUSION: To our knowledge this is the first study to show elevated levels of BAFF and APRIL in CSF of SLE patients. APRIL was augmented in NPSLE patients compared with SLE patients without CNS involvement. APRIL and BAFF antagonists breeching the blood-brain barrier therefore could have beneficial effects on SLE patients, in particular patients with NPSLE.