Characterisation of choroid plexus-infiltrating T cells reveals novel therapeutic targets in murine neuropsychiatric lupus.

OBJECTIVE: Diffuse central nervous system manifestations, referred to as neuropsychiatric lupus (NPSLE), are observed in 20-40% of lupus patients and involve complex mechanisms that have not yet been adequately elucidated. In murine NPSLE models, choroid plexus (ChP)-infiltrating T cells have not been fully evaluated as drivers of neuropsychiatric disease. METHOD: Droplet-based single-cell transcriptomic analysis (single-cell RNA sequencing) and immune T-cell receptor profiling were performed on ChP tissue from MRL/lpr mice, an NPSLE mouse model, at an 'early' and 'late' disease state, to investigate the infiltrating immune cells that accumulate with NPSLE disease progression. RESULTS: We found 19 unique clusters of stromal and infiltrating cells present in the ChP of NPSLE mice. Higher resolution of the T-cell clusters uncovered multiple T-cell subsets, with increased exhaustion and hypoxia expression profiles. Clonal analysis revealed that the clonal CD8+T cell CDR3 sequence, ASGDALGGYEQY, matched that of a published T-cell receptor sequence with specificity for myelin basic protein. Stromal fibroblasts are likely drivers of T-cell recruitment by upregulating the VCAM signalling pathway. Systemic blockade of VLA-4, the cognate ligand of VCAM, resulted in significant resolution of the ChP immune cell infiltration and attenuation of the depressive phenotype. CONCLUSION: Our analysis details the dynamic transcriptomic changes associated with murine NPSLE disease progression, and highlights its potential use in identifying prospective lupus brain therapeutic targets.

Ectopic CD4+ T cells in choroid plexus mediate neuropsychiatric lupus symptoms in mice via interferon-γ induced microglia activation.

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a disabling and potentially life-threatening complication of SLE. This study aims to investigate whether ectopic CD4+ T cells in the choroid plexus mediate NPSLE in mice. Intracerebroventricular (ICV) injection of anti-CD4 antibody effectively depleted CP-resident CD4+ T cells and alleviated NPSLE-like symptoms in MRL/lpr mice. Following ICV injection, the majority of isolated lupus CD4+ T cells from donor MRL/lpr mice predominantly stayed in the CP for at least 28 days in recipient C57BL/6 mice, while nearly all isolated CD4+ T cells from MRL/MpJ mice disappeared within 7 days. ICV injection of lupus CD4+ T cells resulted in NPSLE-like symptoms, including impaired behavioral performances, increased microglial activation, and abnormal microstructure changes. Flow cytometry analysis revealed that the majority of isolated lupus CD4+ T cells were positive for IFN-γ. Neutralizing intracerebral IFN-γ alleviated NPSLE-like symptoms in MRL/lpr mice. Moreover, ICV injection of anti-IFN-γ antibody or microglial depletion by PLX3397 benefited most NPSLE-like symptoms in lupus CD4+ T-treated mice, while ICV injection of IFN-γ mimicked most NPSLE-like symptoms. In conclusion, CP-resident lupus CD4+ T cells contribute to NPSLE-like symptoms in mice via Interferon-γ induced microglia activation. Depleting CP-resident lupus CD4+ T cells, interferon-γ, or activated microglia may be potential therapeutic targets for NPSLE.

Beyond paraneoplastic neurological syndromes: Anti-neuronal antibodies in neuropsychiatric systemic lupus erythematosus.

INTRODUCTION: Anti-neuronal antibodies target antigens produced by tumour cells and cells of nervous system. These antibodies are formed as a result of autoimmune response elicited by the underlying malignancy, when proteins restricted to immune privileged neurons are presented by the tumour. Previous studies have shown presence of anti-neuronal antibodies in systemic lupus erythematosus and neuropsychiatric lupus (NPSLE) but information on individual antibodies and their pathogenic role is lacking. AIMS/OBJECTIVE: To assess the frequency of anti-neuronal antibodies in our neuropsychiatric lupus cohort and to assess any significant association with specific neurological syndrome and to see if the antibodies were more likely to occur in active rather than inactive neuropsychiatric lupus. METHODOLOGY: This cross-sectional study was conducted in our center from 2019 to 2022. Neuropsychiatric manifestations were defined according to 1999 American College of Rheumatology (ACR) nomenclature and case definitions for neuropsychiatric lupus. Samples were taken from active or inactive NPSLE patients with their informed consent. Testing was done on an anti-neuronal antigen panel which consisted of [Amphiphysin, CV2, GAD 65, PNMA2 (Ma-2/Ta), Ri, Yo, Hu, recoverin, SOX1, titin, Zic, Tr)] by semi-quantitative Line immune assay. Association between the categorical variables and antibody positivity group was established using chi-square/Fisher's exact test as appropriate. RESULTS: 65 patients were recruited, of which 23 (35%) patients had active NPSLE at the time of sample collection. Anti-neuronal antibodies were positive in 13/65 (20%) patients with anti-Gad 65 antibodies having the highest frequency (6.2%) followed by anti CV 2 (3.1%), anti Sox1 (3.1%), anti Amphiphysin (3.1%) anti recoverin (1.5%), anti Yo (1.5%) and anti Zic (1.5%). The panel of anti-neuronal antibodies did not show any specific association with NPSLE features.However, an interesting finding was that, patients with active disease had higher odds of having anti-neuronal antibodies with an OR = 10 (95% CI:2.38 -42) (p < 0.001) than inactive disease. CONCLUSION: Anti-neuronal antibodies were more likely to be positive in active neuropsychiatric lupus patients, and these antibodies which are commonly used to diagnose paraneoplastic syndromes may have a potential role in the diagnosis of NPSLE.

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.

Microglia-dependent synapse loss in type I interferon-mediated lupus.

Systemic lupus erythematosus (SLE) is an incurable autoimmune disease characterized by autoantibody deposition in tissues such as kidney, skin and lungs. Notably, up to 75% of patients with SLE experience neuropsychiatric symptoms that range from anxiety, depression and cognitive impairment to seizures and, in rare cases, psychosis-collectively this is referred to as central nervous system (CNS) lupus. In some cases, certain autoantibodies, such as anti-NMDAR or anti-phospholipid antibodies, promote CNS lupus. However, in most patients, the mechanisms that underlie these symptoms are unknown. CNS lupus typically presents at lupus diagnosis or within the first year, suggesting that early factors contributing to peripheral autoimmunity may promote CNS lupus symptoms. Here we report behavioural phenotypes and synapse loss in lupus-prone mice that are prevented by blocking type I interferon (IFN) signalling. Furthermore, we show that type I IFN stimulates microglia to become reactive and engulf neuronal and synaptic material in lupus-prone mice. These findings and our observation of increased type I IFN signalling in post-mortem hippocampal brain sections from patients with SLE may instruct the evaluation of ongoing clinical trials of anifrolumab, a type I IFN-receptor antagonist. Moreover, identification of IFN-driven microglia-dependent synapse loss, along with microglia transcriptome data, connects CNS lupus with other CNS diseases and provides an explanation for the neurological symptoms observed in some patients with SLE.

Absence of Neuronal Autoantibodies in Neuropsychiatric Systemic Lupus Erythematosus.

This study aimed to characterise both neuronal autoantibodies and levels of interferon α, two proposed causative agents in neuropsychiatric systemic lupus erythematosus (NPSLE). Cerebrospinal fluid (CSF) and plasma from 35 patients with systemic lupus erythematosus (SLE; 15 with NPSLE) showed no antibodies against natively expressed N-methyl-D-aspartate receptors (NMDARs), or the surface of live hippocampal neurons. By comparison to controls (n = 104), patients with SLE had antibodies that bound to a peptide representing the extracellular domain of NMDARs (p < 0.0001), however, binding was retained against both rearranged peptides and no peptide (r = 0.85 and r = 0.79, respectively, p < 0.0001). In summary, neuronal-surface reactive antibodies were not detected in NPSLE. Further, while interferon α levels were higher in SLE (p < 0.0001), they lacked specificity for NPSLE. Our findings mandate a search for novel biomarkers in this condition. ANN NEUROL 2020;88:1244-1250.

Identification and stratification of systemic lupus erythematosus patients into two transcriptionally distinct clusters based on IFN-I signature.

OBJECTIVE: Despite the significant advancement in the understanding of the pathophysiology of systemic lupus erythematosus (SLE) variable clinical response to newer therapies remain a major concern, especially for patients with lupus nephritis and neuropsychiatric systemic lupus erythematosus (NPSLE). We performed this study with an objective to comprehensively characterize Indian SLE patients with renal and neuropsychiatric manifestation with respect to their gene signature, cytokine profile and immune cell phenotypes. METHODS: We characterized 68 Indian SLE subjects with diverse clinical profiles and disease activity and tried to identify differentially expressed genes and enriched pathways. To understand the temporal profile, same patients were followed at 6 and 12-months intervals. Additionally, auto-antibody profile, levels of various chemokines, cytokines and the proportion of different immune cells and their activation status were captured in these subjects. RESULTS: Multiple IFN-related pathways were enriched with significant increase in IFN-I gene signature in SLE patients as compared to normal healthy volunteers (NHV). We identified two transcriptionally distinct clusters within the same cohort of SLE patients with differential immune cell activation status, auto-antibody as well as plasma chemokines and cytokines profile. CONCLUSIONS: Identification of two distinct clusters of patients based on IFN-I signature provided new insights into the heterogeneity of underlying disease pathogenesis of Indian SLE cohort. Importantly, patient within those clusters retain their distinct expression dynamics of IFN-I signature over the time course of one year despite change in disease activity. This study will guide clinicians and researchers while designing future clinical trials on Indian SLE cohort.

What are the latest clinical findings regarding the association of neurotoxic brain antibodies found in the cerebrospinal fluid in patients with autoimmune disorders?

PURPOSE OF REVIEW: Recently, experiments show that the autoantibodies with direct access to neurons following blood brain barrier (BBB) disruption destroy neurons and lead to remodeling in damaged neurons. These are critical steps in autoantibody-mediated central nervous system disorder called neuropsychiatric syndromes in systemic lupus erythematosus (NPSLE). The purpose of this review is to examine therapeutic opportunities to repress neuronal remodeling by microglia after acute neuronal injury by autoantibodies. RECENT FINDINGS: Recent studies have demonstrated that BBB disruption is a critical step for developing NPSLE, and serum anti-Sm antibodies have been significantly associated with BBB breakdown. In addition, it has been reported that antiglucose regulated protein-78 in patients with SLE also disrupt the BBB. Experiments with anti-N-methyl-D-aspartate antibodies show that HMGB1 and C1q were essential to activate microglia which, in turn, remodel damaged neurons in vivo. Interestingly treatment with angiotensin-converting enzyme inhibitor inactivated microglia and blunted neuronal remodeling as well as positively affected behavioral abnormalities. SUMMARY: BBB disruption, acute neuronal damage and neuronal remodeling by activated microglia are all critical steps for NPSLE development, and each step will afford novel therapeutic targets.

Advanced neuroimaging in neuropsychiatric systemic lupus erythematosus.

PURPOSE OF REVIEW: Neuropsychiatric lupus (NPSLE) comprises a disparate collection of syndromes affecting the central and peripheral nervous systems. Progress in the attribution of neuropsychiatric syndromes to SLE-related mechanisms and development of targeted treatment strategies has been impeded by a lack of objective imaging biomarkers that reflect specific neuropsychiatric syndromes and/or pathologic mechanisms. The present review addresses recent publications of neuroimaging techniques in NPSLE. RECENT FINDINGS: Imaging studies grouping all NPSLE syndromes together are unable to differentiate between NPSLE and non-NPSLE. In contrast, diffusion tensor imaging, FDG-PET, resting, and functional MRI techniques in patients with stable non-NPSLE demonstrate abnormal network structural and functional connectivity and regional brain activity in multiple cortical areas involving the limbic system, hippocampus, frontal, parietal, and temporal lobes. Some of these changes associate with impaired cognitive performance or mood disturbance, autoantibodies or inflammatory proteins. Longitudinal data suggest progression over time. DCE-MRI demonstrates increased Blood-brain barrier permeability. SUMMARY: Study design issues related to patient selection (non-NPSLE vs. NPSLE syndromes, SLE disease activity, medications) are critical for biomarker development. Regional and network structural and functional changes identified with advanced brain imaging techniques in patients with non-NPSLE may be further developed as biomarkers for cognitive and mood disorders attributable to SLE-related mechanisms.

Advances in the diagnosis, pathogenesis and treatment of neuropsychiatric systemic lupus erythematosus.

PURPOSE OF REVIEW: Diagnosing and treating neuropsychiatric systemic lupus erythematosus (NPSLE) remains challenging as the pathogenesis is still being debated. In this review, we discuss studies evaluating recent advances in diagnostic methods, pathogenic mediators and potential treatments. RECENT FINDINGS: Screening tools used for neurodegenerative diseases were found to be both sensitive and moderately specific for cognitive dysfunction in NPSLE. Neuroimaging can be used to distinguish systemic lupus erythematosus (SLE) patients from healthy controls, but further refinement is needed to differentiate between lupus patients with and without neuropsychiatric manifestations. Elevated levels of specific molecules in the cerebrospinal fluid and/or serum, as well as the presence of certain autoantibodies, have been identified as potential biomarkers in attempts to facilitate a more accurate and objective diagnosis. Among such autoantibodies, anti-NR2 and anti-ribosomal P autoantibodies also have a pathogenic role, although newer studies demonstrate that blood-brain barrier damage may not always be required as previously believed. These and other observations, together with new evidence for disease attenuation after microglial modulation, suggest direct involvement of the central nervous system in NPSLE pathogenesis. SUMMARY: Neuropsychiatric involvement of SLE includes a variety of symptoms that impact quality of life and patient prognosis. There have been recent advances in improving the diagnosis of NPSLE as well as in dissecting the underlying pathogenesis. The attenuation of neuropsychiatric disease in mouse models demonstrates the potential for targeted therapies, which are based on a clearer understanding of the pathogenesis of NPSLE. Further assessment of these treatments is required in NPSLE patients, as well as the potential use of neuroimaging to distinguish between SLE patients with or without neuropsychiatric manifestations.

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.

Association of anti-NR2 and U1RNP antibodies with neurotoxic inflammatory mediators in cerebrospinal fluid from patients with neuropsychiatric systemic lupus erythematosus.

BACKGROUND: Autoantibodies (auto Abs) and inflammatory mediators (IMs) in cerebrospinal fluid (CSF) may be involved in the pathogenesis of neuropsychiatric systemic lupus erythematosus (NPSLE). It is suggested that anti-N-methyl D-aspartate receptor NR2 subunit (NR2) Ab can develop NP manifestation after blood-brain barrier (BBB) abruption. We also reported the association between NPSLE and CSF anti-U1RNP Ab. In the present study, combined effects of CSF anti-NR2 and anti-U1RNP Abs on IMs in patients with NPSLE were examined. METHODS: CSF samples were collected from 69 patients with NPSLE and 13 non-NPSLE controls. CSF anti-NR2 and anti-U1RNP Abs were determined using ELISA. Levels of IL-6, IL-8, and monokine induced by IFN-γ (MIG) in CSF were measured by quantitative multiplex cytokine analysis. RESULTS: CSF IL-6 levels were higher in CSF anti-NR2-positive than in CSF anti-NR2-negative patients (p = 0.003) and non-NPSLE controls (p = 0.015) and were positively correlated with anti-NR2 titer (r = 0.42). CSF IL-8 levels were higher in CSF anti-U1RNP-positive than in CSF anti-U1RNP-negative patients (p = 0.041). CSF MIG levels were more elevated in CSF anti-NR2-positive (p = 0.043) and anti-U1RNP-positive patients (p = 0.029) than in non-NPSLE controls. Additionally, in double positive (DP; both anti-NR2 and U1RNP Ab positive) group, CSF IL-6 and MIG levels were significantly higher than in the double negative (DN; both anti-NR2 and U1RNP Ab negative) group. However, combined effect of both Abs on IM elevation and clinical manifestation was not clear. CONCLUSIONS: CSF anti-NR2 and anti-U1RNP Abs have different effects on the elevation of CSF IM levels in patients with NPSLE. Additional effect of anti-U1RNP Abs on anti-NR2 Ab-mediated NP manifestation, however, was not recognized in our study.

Immunological biomarkers in neuropsychiatric systemic lupus erythematosus: a comparative cross-sectional study from a tertiary care center in South India.

INTRODUCTION: The prevalence of various immunological biomarkers in neuropsychiatric systemic lupus erythematosus (NPSLE) differs among various patients with varied neuropsychiatric manifestations and different populations. We studied the prevalence of these biomarkers; especially the neuron specific autoantibodies in patients with systemic lupus erythematosus (SLE) and compared them among patients with and without neuropsychiatric involvement. METHODOLOGY: This is a comparative cross-sectional study conducted in a tertiary care hospital in South India. The prevalence of immunological biomarkers including complement levels, systemic and brain specific autoantibodies (anti-myelin antibody, anti-myelin oligodendrocyte glycoprotein and anti-myelin-associated glycoprotein antibody) were assessed and compared among those with and without NPSLE and with different NPSLE manifestations. RESULTS: A total of 522 SLE patients were enrolled in the study. The mean age of the study participants was 28.5 ± 8.8 years and 93.5% were women. Neuropsychiatric manifestations were seen in 167 (32%) patients. Seizure was the most common neuropsychiatric manifestation seen in 41.3%, followed by psychosis (18.6%), mood disorder (16.8%), stroke (10.8%), mononeuropathy (10.2%), headache (9.6%), acute confusional state (6.6%) and aseptic meningitis (5.4%). Patients with NPSLE had a higher SLE disease activity index score. Most of the autoantibodies, that is anticardiolipin antibody (aCL), anti-ß2 glycoprotein 1 antibody (ß2GP1), lupus anticoagulant (LA), anti-nucleosome, anti-ribosomal P, anti-Ro52, anti-Ro60 and anti-La, were seen in higher proportion in the NPSLE group, although the difference failed to reach statistical significance. On subgroup analysis, psychosis was significantly higher in patients with anti-ribosomal P positivity than without (11.8% versus 4.1%, p.0.007; odds ratio (OR) 3.1, confidence interval (CI) 1.4-6.8), while stroke had a higher proportion among those with positive b2GP1 IgG (6.3% versus 1.8%, p.0.03; OR 3.6, CI 1.2-11.0). A higher proportion of demyelination was seen among the LA positive than the negative (10.3% versus 0.2%, p.0.03; OR 5.39, CI 1.15-24.17) and anti-myelin oligodendrocyte glycoprotein in mood disorder (14.3% versus 3.4%, p = 0.03; OR 4.66, CI 1.13-19.13). CONCLUSION: No single biomarker correlated with NPSLE. Among different NPSLE manifestations, the prevalence of IgG ß2GP1 in stroke, LA in demyelination, anti-ribosomal P in psychosis and anti-myelin oligodendrocyte glycoprotein in mood disorder were higher. Further studies on the pathogenic mechanisms underlying NPSLE and its different manifestations may help us to identify better biomarkers.

Update on the pathogenesis of central nervous system lupus.

PROPOSE OF REVIEW: Neuropsychiatric systemic lupus erythematosus (NPSLE) is an emerging frontier in lupus care encompassing a wide spectrum of clinical manifestations. Its pathogenesis remains poorly understood because of the complexity of pathophysiologic mechanisms involved and limited access to tissue. We highlight recent advances in the pathophysiology of neuropsychiatric lupus. RECENT FINDINGS: Disruption of blood-brain barrier (BBB) facilitating entrance of neurotoxic antibodies into the central nervous system (CNS), neuroinflammation and cerebral ischemia are the key mechanisms. Disruption of the BBB may occur not only at the traditional BBB, but also at the blood-cerebrospinal fluid barrier. Certain autoantibodies, such as anti-N-methyl-D-aspartate receptors, antiribosomal P and antiphospholipid antibodies may cause injury in subsets of patients with diffuse neuropsychiatric disease. Activation of microglia via autoantibodies, interferon-a or other immune reactants, may amplify the inflammatory response and promote neuronal damage. New inflammatory pathways, such as TWEAK/Fn14, Bruton's tyrosine kinase, Nogo-a and ACE may represent additional potential targets of therapy. Novel neuroimaging techniques suggest alterations in brain perfusion and metabolism, increased concentration of neurometabolites, indicative of glial activation, vasculopathy and neuronal impairment. SUMMARY: NPSLE encompasses a diverse phenotype with distinct pathogenic mechanisms, which could be targeted by novel therapies or repositioning of existing drugs.

A De Novo Frameshift Mutation in TNFAIP3 Impairs A20 Deubiquitination Function to Cause Neuropsychiatric Systemic Lupus Erythematosus.

PURPOSE: Genome-wide association study of systemic lupus erythematosus (SLE) revealed tumor necrosis factor alpha-induced protein 3 (TNFAIP3, A20) as a susceptibility gene. Here, we report a de novo mutation in TNFAIP3 in a Chinese patient with neuropsychiatric SLE (NPSLE). METHODS: Whole exome sequencing was performed for the patient and healthy members from the family. Suspected pathogenic variants were further analyzed and co-segregation was confirmed by Sanger sequencing. Real-time PCR and western blot were performed with peripheral blood mononuclear cells (PBMCs) and patient-derived T cells. Transfected HEK293T cells, human umbilical vein endothelial cells, normal human astrocytes, and microglia were used for in vitro studies. RESULTS: A de novo frameshift mutation in TNFAIP3 was found in the NPSLE patient. Western blot analysis showed activated NF-κB and mitogen-activated protein kinase pathways. Real-time PCR revealed elevated expression of pro-inflammatory cytokines. On immunoprecipitation assay, the mutant A20 altered the K63-linked ubiquitin level of TRAF6 via its ubiquitin-editing function. CONCLUSIONS: The mutant A20 may play a role in weakening the tight junction of the blood-brain barrier to cause neurologic symptoms. We report a rare variant of TNFAIP3 in a patient with NPSLE and reveal its autoimmune disease-causing mechanism in both peripheral tissues and the central nervous system.

Cerebral blood flow abnormalities in neuropsychiatric systemic lupus erythematosus.

OBJECTIVE: To investigate the clinical characteristics, imaging changes and early diagnostic methods of neuropsychiatric systemic lupus erythematosus (NPSLE). METHODS: Thirty-five SLE patients, of which 16 had overt neuropsychiatric symptoms, underwent examination for multiple autoantibodies, including anti-double-stranded DNA (anti-dsDNA) antibody, anti-nucleosome antibody, anti-cardiac-phospholipid antibody (aCL)-IgG, aCL-IgM, anti-ß2-glycoprotein I antibody and anti-ribosomal P antibody, and the SLEDAI score of every patient was recorded. All patients further received neuropsychological tests, including the Mini-Mental State Examination, the Self-Rating Anxiety Scale and the Self-Rating Depression Scale. Imaging examination using 3D arterial spin labeling was performed on 3.0 T MRI scanners. After processing the 3D arterial spin labeling image, the cerebral blood flow map was obtained and the cerebral blood flow value was calculated. RESULTS: The values of anti-dsDNA, anti-nucleosome antibody, aCL-IgG and anti-ß2-glycoprotein I antibodies were significantly higher in the NPSLE group than those in the SLE group. The SLEDAI scores of the NPSLE group were significantly higher than those of the SLE group. There were no significant differences between the NPSLE group and the SLE group in the directional ability, memory, attention, numeracy, recall ability or language ability scores on the Mini-Mental State Examination scale. Furthermore, there were no symptoms of anxiety or depression in any of the patients, according to the Self-Rating Anxiety Scale and Self-Rating Depression Scale. In the 35 patients with SLE, decreases in blood perfusion were seen in some areas, and were unilateral and asymmetrically distributed. There was obvious asymmetry between sides in areas including the frontal lobe, temporal lobe, parietal lobe and occipital lobe. The incidence of perfusion decreases in frontal lobe in the NPSLE group was significantly higher than in the SLE group. CONCLUSION: Neurological lesions in SLE patients can be detected by arterial spin labeling. Cerebral blood flow abnormalities may be helpful for the early diagnosis of neurological lesions in NPSLE.

Anti-IFNAR treatment does not reverse neuropsychiatric disease in MRL/lpr lupus mice.

OBJECTIVE: Many systemic lupus erythematosus patients display a type I interferon (IFN) signature, and IFNα levels positively correlate with disease severity. Previous studies blocking the type I IFN pathway systemically in lupus models showed some beneficial effects. However, its effects on neuropsychiatric manifestations have yet to be carefully assessed, even though IFNα has been associated with induction of depression. Our aim was to investigate whether disrupting the type I IFN pathway would attenuate the development of murine neuropsychiatric lupus. METHODS: Female MRL/lpr mice were administered an antitype I IFN receptor (IFNAR) antibody or a control antibody intraperitoneally three times weekly for 12 weeks starting at age 4-5 weeks. Behavior was assessed during and at the end of the treatment schedule. RESULTS: No significant differences were seen between the anti-IFNAR- and control-treated mice when assessing for depression-like behavior or cognitive dysfunction, although anti-IFNAR antibody-treated mice displayed significant decreases in levels of IFN-stimulated genes. Anti-IFNAR treatment also did not significantly improve brain histology, cellular infiltration, or blood-brain barrier integrity. CONCLUSIONS: Surprisingly, our results showed no improvement in neuropsychiatric disease and suggest that the role of IFNAR signaling in the pathogenesis of neuropsychiatric lupus continues to need to be carefully assessed.

The clinical significance of ubiquitin carboxyl hydrolase L1 and its autoantibody in neuropsychiatric systemic lupus erythematosus.

OBJECTIVES: To identify specific cerebrospinal fluid (CSF) biomarkers for the diagnosis and disease severity evaluation of neuropsychiatric systemic lupus erythematosus (NPSLE). METHODS: Patients presented with neuropsychiatric symptoms were recruited and categorised as 36 NPSLE, 19 SLE controls, 4 other connective tissue disease (CTD) controls and 10 nervous system disorder (NSD) controls. The NPSLE group consisted of severe NPSLE (sNPSLE) and mild NPSLE (mNPSLE). Potential biomarkers were determined by Luminex multiplex assay and enzyme-linked immunosorbent assay. RESULTS: 1) Among a variety of neurological disease-related proteins, only ubiquitin carboxyl hydrolase L1 (UCH-L1) levels were significantly elevated in the CSF samples of sNPSLE patients compared with those of mNPSLE patients (p=0.020) and SLE controls (p=0.037). CSF UCH-L1 levels were significantly positively correlated with SLE disease activity index and overlap number of NPSLE manifestations. 2) CSF anti-UCH-L1 autoantibodies were significantly elevated in patients with NPSLE in comparison to all of the control groups, with a sensitivity of 53% and a specificity of 91% for NPSLE. CSF anti-UCH-L1 levels were associated with organ involvement and were positively correlated with serum anti-UCH-L1 levels in the NPSLE patients (r=0.4551, p=0.0382). CONCLUSIONS: Anti-UCH-L1 is a promising CSF biomarker for NPSLE diagnosis with high specificity, and the elevated levels of CSF UCH-L1 reflect the clinical severity of NPSLE. The elevation of UCH-L1 and its autoantibody in NPSLE patients showed us novel aetiological insights on NPSLE.

Anti-N-Methyl-D-Aspartic Acid Receptor 2 (Anti-NR2) Antibody in Neuropsychiatric Lupus Serum Damages the Blood-Brain Barrier and Enters the Brain.

BACKGROUND Brain microvessel endothelial cells constitute an important component in the blood-brain barrier. Cell-culture-based models of the blood-brain barrier (BBB) have been extensively applied in pharmacology, pathology and physiology. This study investigated effects of anti-N-methyl-D-aspartic acid receptor 2 (anti-NR2), N-methyl-D-aspartic acid (NMDA) receptor antibodies, NMDA receptor antagonists, and NMDA receptor agonists on brain microvessel endothelial cell models, and verified the effect of anti-NR2 antibody on the BBB as a receptor agonist. MATERIAL AND METHODS The primary brain microvessel endothelial cells were isolated and cultured, and an in vitro BBB model was established based on microvessel endothelial cells. Anti-NR2 antibody, glutamic acid, ifenprodil, and memantine were added in the BBB model to analyze changes in transepithelial electrical resistance (TEER) and to examine the permeability of the brain microvessel endothelial cell model. RESULTS The results showed that TEER values were significantly decreased by the addition of anti-NR2 antibody and glutamate, but were significantly increased by the addition of ifenprodil and memantine. TEER values showed no changes when treated by anti-NR2 antibody and ifenprodil, as well as anti-NR2 antibody and memantine. When dexamethasone was added, the TEER values increased by 23.8%, 39.4%, and 29.6% by treating with anti-NR2 antibody, positive cerebrospinal fluid, and positive serum, respectively. CONCLUSIONS Our findings show that anti-NR2 antibody in neuropsychiatric lupus serum can damage the BBB and enter the brain.

Mechanisms of neuropsychiatric lupus: The relative roles of the blood-cerebrospinal fluid barrier versus blood-brain barrier.

The pathogenesis of neuropsychiatric lupus (NPSLE) is believed to include the entry of circulating neuropathic antibodies to the brain via a pathologically permeable blood-brain barrier (BBB). Nevertheless, direct evidence of BBB pathology or mechanisms underlying BBB dysfunction is missing. Here, we examined BBB integrity in an established NPSLE mouse model (MRL/faslpr/lpr). Surprisingly, challenging the barrier with various exogenous tracers demonstrated insignificant changes in BBB permeability. Furthermore, electron microscopy showed no ultrastructure changes supporting hyper-permeability. However, we found that abnormal function of the blood-cerebrospinal fluid barrier (BCSFB) in the choroid plexus underlies brain exposure to neuropathic antibodies. Considerable intrathecal lymphocyte infiltration likely occurs through the BCSFB, accompanied by epithelial hyper-permeability to antibodies. Our results challenge the commonly held view of BBB disruption in NPSLE, supporting a shift in focus to BCSFB dysfunction as a causative factor in the disease.