Evaluation of a novel particle-based assay for detecting SLE-related autoantibodies

Anti-dsDNA, anti-Sm, and anti-ribosomal-P autoantibodies are hallmarks of systemic lupus erythematosus (SLE), being anti-dsDNA and anti-Sm included in 2019-ACR/EULAR SLE-Classification Criteria. Enzyme-linked (ELISA) and chemiluminescence assays (CIA) are widely established in immunology laboratories, but new technologies, such as particle-based multi-analyte technology (PMAT), are nowadays available. The present study aimed to compare the presence of anti-dsDNA and anti-Sm autoantibodies measured by CIA and PMAT and analyze diagnostic and clinical SLE activity performance. Anti-ribosomal-P autoantibodies by PMAT were also included. Consequently, anti-dsDNA and anti-Sm detected by CIA showed substantial agreement with PMAT (Cohen's kappa = 0.662 and 0.671, respectively). Anti-dsDNA autoantibodies measured by PMAT showed a positive correlation with clinical SLEDAI-2K (p < 0.001) and a negative correlation with complement consumption (p < 0.001). Anti-Sm and anti-ribosomal-P autoantibodies showed a positive correlation with SLEDAI-2K (p < 0.001 and p = 0.001, respectively) and a negative correlation with complement consumption (p < 0.001 and p = 0.001, respectively). Finally, anti-Sm autoantibodies were associated with renal involvement (p < 0.05).

Construction of molecular subgroups in childhood systemic lupus erythematosus using bioinformatics

BACKGROUND

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder. In patients with childhood SLE (cSLE), the onset of the disease occurs before 18 years of age and accounts for a high proportion of childhood autoimmune diseases. Adult SLE and cSLE differ in terms of clinical manifestations, gene expression profiles, and treatment. Because current diagnostic methods do not meet clinical requirements, researchers currently use transcriptome analysis to investigate the characteristics of the cSLE genome. In the present study, we used bioinformatics methods to genotype cSLE and identify potential therapeutic targets.

METHODS

The transcriptomes of 952 patients with cSLE and 94 normal controls were obtained from the Gene Expression Omnibus using unsupervised class learning to determine the genotypes in the microarray dataset, and the clinical characteristics, differentially expressed genes, and biological characteristics of the subtypes were analyzed.

RESULTS

Patients with cSLE were accordingly classified into three subgroups. Subgroup I was associated with lupus nephritis, female patients, and a high SLE disease activity index, and the disease in this subgroup was more severe than that in other subgroups. The SLE disease activity index in subgroup II was low; this subgroup may be related to lupus vasculitis. Subgroup III mostly included male patients and was associated with neuropsychiatric manifestations of lupus.

CONCLUSION

We divided patients with cSLE into three subgroups with different characteristics based on transcriptome data. Our findings provide molecular evidence for future diagnosis and individualized treatment of cSLE.

Novel anti-cytoplasmic antibodies in cerebrospinal fluid and serum of patients with chronic severe mental disorders

OBJECTIVES

There is an emerging role of autoimmune causes related to severe mental disorders (SMD). The clinical approach in patients with chronic SMD and novel anti-central nervous system antibodies is complex.

METHODS

Two corresponding cumulative cases are presented. Cerebrospinal fluid (CSF) and serum were investigated using tissue-based assays.

RESULTS

Both patients suffered from chronic SMD and were negative for well-characterized neuronal antibodies. Patient 1 suffered from a dysexecutive and neurocognitive syndrome with mild abnormalities in automated electroencephalography analysis, elevated CSF protein levels, several serum autoantibodies (including antibodies against endothelial cells), and novel antibodies with a "dotted/scalloped" binding against cytoplasmic structures in CSF. Patient 2 with obsessive-compulsive disorder had left temporal abnormalities on automated magnetic resonance imaging analysis, an elevated CSF/serum albumin quotient, and novel atypical cytoplasmic "spotted" antibody staining in the serum. Patient 1 improved with immunotherapy using high-dose steroids, but patient 2 did not improve under the same treatment.

CONCLUSIONS

The detection of autoantibodies in CSF of chronic SMD may be beneficial in selecting some patients for immunotherapy. The possible impact of novel anti-cytoplasmic antibodies in this context is critically discussed. Further research is needed to establish the underlying pathophysiological processes as well as their diagnostic and therapeutic implications.

Clinical profile of patients with lupus psychosis in a Colombian cohort

The objective of this study is to describe the frequency and the clinical, paraclinical, and treatment profile of patients with lupus psychosis in a Colombian cohort of patients with systemic lupus erythematosus (SLE). This retrospective cohort study evaluated epidemiological and clinical characteristics, results of neuroimaging, analysis of the cerebrospinal fluid, treatment, and disease evolution in patients with lupus psychosis. Among 2,479 patients with SLE, six female patients aged between 20 and 50 years with a diagnosis of lupus psychosis were identified. In two patients, psychosis was present at disease onset and in the other four, SLE was already present, although the majority of them were diagnosed less than two years prior to the onset of psychosis. The entire cohort had high disease activity as measured by SLEDAI-2K. We found concomitant cutaneous, joint, and hematological alterations. Cerebrospinal fluid data were obtained in half of the patients and were normal. We performed brain tomography on most of our patients, which was almost always described as normal. In 5 out of 6 patients, the induction therapy to treat psychosis was based on steroids, and in the majority of them, a resolution of psychiatric symptoms was observed after initiating treatment. Lupus psychosis is a rare event that usually occurs early in the course of the disease and is associated with other manifestations of SLE. This investigation mainly found concomitant cutaneous, joint, and hematological manifestations, with a favorable outcome after treatment, as described in the literature.

Association of Antiribosomal P Antibody with Neurological and Systemic Manifestations in Patients with Systemic Lupus Erythematosus in Southwestern Colombia

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by heterogeneous pathogenesis, various clinical manifestations, and a broad spectrum of autoantibodies which recognize different cellular components. This study examines the clinical significance and serological associations of serum antiribosomal P antibodies (anti-P) derived from SLE patients in a population from southwestern Colombia.

METHODS

We performed a cross-sectional study of 66 SLE patients. Serum antiribosomal P0 autoantibodies were detected by line immunoassay using the ANA-LIA MAXX kit and processed on the automated HumaBlot 44FA system (Human Diagnostics, Germany).

RESULTS

Of the 66 SLE patients included in the study, 17 patients (25.76%) showed anti-P positivity by line immunoassay (IA), 47 (71.21%) were negative, and results from 2 patients were indeterminate. We did not find an association with neuropsychiatric SLE (NPSLE), renal, or hepatic disorders (P > 0.05). Laboratory findings indicated that anti-P positivity was significantly associated to anti-Smith (P = 0.001), anti-Ro60/SSA (P = 0.046), and anti-dsDNA antibodies (P = 0.034), the latter being true only when performed using indirect immunofluorescence (IIF).

CONCLUSION

The anti-P antibodies are not associated with clinical manifestations such as NPSLE, lupus nephritis, or hepatic involvement in the southwest Colombian SLE population. Moreover, we confirmed previously reported association between anti-P antibody, serum anti-dsDNA, and anti-Smith.

Neuronal surface P antigen (NSPA) modulates postsynaptic NMDAR stability through ubiquitination of tyrosine phosphatase PTPMEG

Background

Cognitive dysfunction (CD) is common among patients with the autoimmune disease systemic lupus erythematosus (SLE). Anti-ribosomal P autoantibodies associate with this dysfunction and have neuropathogenic effects that are mediated by cross-reacting with neuronal surface P antigen (NSPA) protein. Elucidating the function of NSPA can then reveal CD pathogenic mechanisms and treatment opportunities. In the brain, NSPA somehow contributes to glutamatergic NMDA receptor (NMDAR) activity in synaptic plasticity and memory. Here we analyze the consequences of NSPA absence in KO mice considering its structural features shared with E3 ubiquitin ligases and the crucial role of ubiquitination in synaptic plasticity.

Results

Electrophysiological studies revealed a decreased long-term potentiation in CA3-CA1 and medial perforant pathway-dentate gyrus (MPP-DG) hippocampal circuits, reflecting glutamatergic synaptic plasticity impairment in NSPA-KO mice. The hippocampal dentate gyrus of these mice showed a lower number of Arc-positive cells indicative of decreased synaptic activity and also showed proliferation defects of neural progenitors underlying less adult neurogenesis. All this translates into poor spatial and recognition memory when NSPA is absent. A cell-based assay demonstrated ubiquitination of NSPA as a property of RBR-type E3 ligases, while biochemical analysis of synaptic regions disclosed the tyrosine phosphatase PTPMEG as a potential substrate. Mice lacking NSPA have increased levels of PTPMEG due to its reduced ubiquitination and proteasomal degradation, which correlated with lower levels of GluN2A and GluN2B NMDAR subunits only at postsynaptic densities (PSDs), indicating selective trafficking of these proteins out of PSDs. As both GluN2A and GluN2B interact with PTPMEG, tyrosine (Tyr) dephosphorylation likely drives their endocytic removal from the PSD. Actually, immunoblot analysis showed reduced phosphorylation of the GluN2B endocytic signal Tyr1472 in NSPA-KO mice.

Conclusions

NSPA contributes to hippocampal plasticity and memory processes ensuring appropriate levels of adult neurogenesis and PSD-located NMDAR. PTPMEG qualifies as NSPA ubiquitination substrate that regulates Tyr phosphorylation-dependent NMDAR stability at PSDs. The NSPA/PTPMEG pathway emerges as a new regulator of glutamatergic transmission and plasticity and may provide mechanistic clues and therapeutic opportunities for anti-P-mediated pathogenicity in SLE, a still unmet need.

Neurofilament light is a biomarker of brain involvement in lupus and primary Sjögren's syndrome

Background

To test the hypothesis that neurofilament light (NfL) in CSF is a biomarker of CNS involvement in patients with systemic lupus erythematosus (SLE) and primary Sjögren’s syndrome (pSS), we measured NfL in CSF from 52 patients with lupus and 54 with pSS and explored associations with clinical, structural, immunological and biochemical abnormalities.

Methods

In CSF, we measured NfL, anti-P antibodies, protein S100B and TWEAK by ELISA and anti-NR2 antibodies by electrochemiluminescence. Anti-phospholipid antibodies and routine immunological tests were performed in blood. IgG and albumin were measured in CSF and serum for assessment of the blood–brain barrier function (Q-albumin) and intrathecal IgG production (IgG index). Cerebral MRI and neuropsychological testing were performed.

Results

A multivariable regression model showed that increasing CSF anti-NR2 antibody levels were associated with increasing NfL levels in patients with SLE (B 1.27, 95% CI 0.88–1.65, p < 0.001). Age contributed significantly in the model (B 0.04, 95% CI 0.03–0.05, p < 0.001). Similar findings were observed in the pSS group. Adjusted for age and sex, no associations were found between NfL levels and any MRI data. In SLE patients, higher NfL concentrations were associated with impairments in psychomotor speed and motor function, and in pSS with motor dysfunction. These associations remained in multivariable regression models.

Conclusions

Increased concentration of NfL in CSF is a marker of cerebral involvement in patients with SLE and pSS, is strongly associated with the presence of anti-NR2 antibodies, and correlates with cognitive impairment in several domains.

Electronic supplementary material

Supplementary information is available for this paper at 10.1007/s00415-020-10290-y.

New insights into the role of antinuclear antibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by antinuclear antibodies (ANAs) that form immune complexes that mediate pathogenesis by tissue deposition or cytokine induction. Some ANAs bind DNA or associated nucleosome proteins, whereas other ANAs bind protein components of complexes of RNA and RNA-binding proteins (RBPs). Levels of anti-DNA antibodies can fluctuate widely, unlike those of anti-RBP antibodies, which tend to be stable. Because anti-DNA antibody levels can reflect disease activity, repeat testing is common; by contrast, a single anti-RBP antibody determination is thought to suffice for clinical purposes. Experience from clinical trials of novel therapies has provided a new perspective on ANA expression during disease, as many patients with SLE are ANA negative at screening despite previously testing positive. Because trial results suggest that patients who are ANA negative might not respond to certain agents, screening strategies now involve ANA and anti-DNA antibody testing to identify patients with so-called 'active, autoantibody-positive SLE'. Evidence suggests that ANA responses can decrease over time because of the natural history of disease or the effects of therapy. Together, these findings suggest that, during established disease, more regular serological testing could illuminate changes relevant to pathogenesis and disease status.

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.

Intracerebroventricular administration of lupus serum induces microglia activation and leukocyte adhesion in the cerebromicrovasculature of mice

BACKGROUND

Central nervous system (CNS) involvement is commonly seen in the patients with system lupus erythematosus (SLE). Mechanisms underlying CNS damage in SLE remain largely unknown. Accumulating evidence suggest that activation of microglia in CNS plays an important role in the inflammatory responses in neurological diseases. The aim of this study is to examine the involvement of microglia in the CNS inflammatory responses induced by circulating serum of SLE patients.

METHODS

We performed intracerebroventricular (ICV) injection of serums collected from SLE patients or healthy controls to mice, and examined phenotypic changes of microglia, the levels of cytokines, chemokine and adhesion molecules in the brain. Intravital microscopy was used to observe leukocyte rolling and adhesion in the cerebromicrovasculature. We further examined whether minocycline can block inflammatory responses induced by SLE serum. In vitro experiments were conducted to examine whether IgGs from the sera of SLE patients or healthy control can activate the primary cultured microglia.

RESULTS

We found that ICV injection of SLE serum increases morphological activation of microglia in the cortex and hippocampus. Inflammatory mediators including pro-inflammatory cytokines (IL-1, IL-6 and TNF-α), chemokine (CCL2 and CCL5) and adhesion molecules (P-selectin and ICAM-1) were significantly elevated in the brains of SLE-serum-treated mice. Using intravital microscopy, we demonstrated that SLE serum promotes leukocyte rolling and adhesion. Furthermore, suppression of microglia activation by systemically using minocycline could decrease the levels of inflammatory molecular, and prevent leukocyte rolling and adhesion. The in vitro experiments revealed that IgG from SLE sera could be engulfed by microglia and stimulated the microglia to secret pro-inflammatory cytokines.

CONCLUSION

Our data suggest that the activation of microglia, which promotes leukocyte adhesion to the brain microvasculature, is an important pathological mechanism of CNS involvement in SLE.

Psychosis in Systemic Lupus Erythematosus: Results From an International Inception Cohort Study

Objective

To determine, in a large, multiethnic/multiracial, prospective inception cohort of patients with systemic lupus erythematosus (SLE), the frequency, attribution, clinical, and autoantibody associations with lupus psychosis and the short‐ and long‐term outcomes as assessed by physicians and patients.

Methods

Patients were evaluated annually for 19 neuropsychiatric (NP) events including psychosis. Scores on the Systemic Lupus Erythematosus Disease Activity Index 2000, the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index, and the Short Form 36 (SF‐36) were recorded. Time to event and linear regressions were used as appropriate.

Results

Of 1,826 SLE patients, 88.8% were female and 48.8% were Caucasian. The mean ± SD age was 35.1 ± 13.3 years, the mean ± SD disease duration was 5.6 ± 4.2 months, and the mean ± SD follow‐up period was 7.4 ± 4.5 years. There were 31 psychotic events in 28 of 1,826 patients (1.53%), and most patients had a single event (26 of 28 [93%]). In the majority of patients (20 of 25 [80%]) and events (28 of 31 [90%]), psychosis was attributed to SLE, usually either in the year prior to or within 3 years of SLE diagnosis. Positive associations (hazard ratios [HRs] and 95% confidence intervals [95% CIs]) with lupus psychosis were previous SLE NP events (HR 3.59 [95% CI 1.16–11.14]), male sex (HR 3.0 [95% CI 1.20–7.50]), younger age at SLE diagnosis (per 10 years) (HR 1.45 [95% CI 1.01–2.07]), and African ancestry (HR 4.59 [95% CI 1.79–11.76]). By physician assessment, most psychotic events resolved by the second annual visit following onset, in parallel with an improvement in patient‐reported SF‐36 summary and subscale scores.

Conclusion

Psychosis is an infrequent manifestation of NPSLE. Generally, it occurs early after SLE onset and has a significant negative impact on health status. As determined by patient and physician report, the short‐ and long‐term outlooks are good for most patients, although careful follow‐up is required.

The Interaction between the Ribosomal Stalk Proteins and Translation Initiation Factor 5B Promotes Translation Initiation

Ribosomal stalk proteins recruit translation elongation GTPases to the factor-binding center of the ribosome. Initiation factor 5B (eIF5B in eukaryotes and aIF5B in archaea) is a universally conserved GTPase that promotes the joining of the large and small ribosomal subunits during translation initiation. Here we show that aIF5B binds to the C-terminal tail of the stalk protein. In the cocrystal structure, the interaction occurs between the hydrophobic amino acids of the stalk C-terminal tail and a small hydrophobic pocket on the surface of the GTP-binding domain (domain I) of aIF5B. A substitution mutation altering the hydrophobic pocket of yeast eIF5B resulted in a marked reduction in ribosome-dependent eIF5B GTPase activity in vitro In yeast cells, the eIF5B mutation affected growth and impaired GCN4 expression during amino acid starvation via a defect in start site selection for the first upstream open reading frame in GCN4 mRNA, as observed with the eIF5B deletion mutant. The deletion of two of the four stalk proteins diminished polyribosome levels (indicating defective translation initiation) and starvation-induced GCN4 expression, both of which were suppressible by eIF5B overexpression. Thus, the mutual interaction between a/eIF5B and the ribosomal stalk plays an important role in subunit joining during translation initiation in vivo.

Interactions of antisera to different Chlamydia and Chlamydophila species with the ribosomal protein RPS27a correlate with impaired protein synthesis in a human choroid plexus papilloma cell line

Chlamydia trachomatis (CT) and the Chlamydophila species (CS) Chlamydophila pneumoniae (CPn), and Chlamydophila psittaci (CPs) are suggested to induce autoantibodies causative of several human autoimmune disorders like rheumatoid arthritis and systemic lupus erythematosus (SLE). The aim of the present study was therefore to identify cellular protein interaction partners with antisera to CT (α-CT) or CS (α-CS) and to identify functional consequences of such interaction in vitro. As detected with a commercial first trimester human prenatal brain multiprotein array (hEXselect, Engine, Germany), the most frequent interaction partner with both α-CT and α-CS was the ribosomal small subunit protein RPS27a. This could be confirmed by Western blot analysis with a recombinant RPS27a sample. In addition, immunocytochemistry with both antisera in the human choroid plexus papilloma cell line HIBCPP revealed a granular cytoplasmic staining, and Western blot analysis with whole-cell protein samples of HIBCPP cells revealed both antisera to label protein bands of different molecular weights and intensity. By 2D Western blot analysis and mass spectrometry, one of the protein spots interacting with α-CT could be identified as the RPS27a. Finally, two different methods for the detection of protein synthesis activity, the SUnSET technique and an HPG fluorescence assay revealed both antisera to cause reduced translational activity in HIBCPP cells. Together with previous findings of RPS27a as an autoimmune target in a mouse model of systemic lupus erythematosus (SLE), these results suggest that infections with CT and/or CS could induce SLE-associated immune modifications. However, direct evidence for a pathogenic role of these interactions for SLE demands further investigations.