Neuropsychiatric systemic lupus erythematosus: pathogenesis and biomarkers

Neuropsychiatric Systemic Lupus Erythematosus in Older Adults: Diagnosis and Management

Systemic lupus erythematosus (SLE) is a multisystem chronic autoimmune disease with variable clinical manifestations. Neuropsychiatric systemic lupus erythematosus (NPSLE) includes the neurologic syndromes of the central, peripheral and autonomic nervous system and the psychiatric syndromes observed in patients with SLE. Neuropsychiatric systemic lupus erythematosus events may present as an initial manifestation of SLE or may be diagnosed later in the course of the disease. Older adults with NPLSE include those who are ageing with known SLE and those with late-onset SLE. The diagnosis of NPSLE across the lifespan continues to be hampered by the lack of sensitive and specific laboratory and imaging biomarkers. In this review, we discuss the particular complexity of NPSLE diagnosis and management in older adults. We first discuss the epidemiology of late-onset NPSLE, then review principles of diagnosis of NPSLE, highlighting issues that are pertinent to older adults and that make diagnosis and attribution more challenging, such as atypical disease presentation, higher medical comorbidity, and differences in neuroimaging and autoantibody investigations. We also discuss clinical issues that are of particular relevance to older adults that have a high degree of overlap with SLE, including drug-induced lupus, cerebrovascular disease and neurocognitive disorders. Finally, we review the management of NPSLE, mainly moderate to high- dose glucocorticoids and immunosuppressants, again highlighting considerations for older adults, such as increased medication (especially glucocorticoids) adverse effects, ageing-related pharmacokinetic changes that can affect SLE medication management, medication dosing and attention to medical comorbidities affecting brain health.

CXCL13 Neutralization Attenuates Neuropsychiatric Manifestations in Lupus-Prone Mice

Neuropsychiatric lupus (NPSLE), the nervous system presentation of systemic lupus erythematosus (SLE), remains challenging to treat due to its unclear pathogenesis and lack of available targeted therapies. A potential contributor to disease progression is brain tertiary lymphoid structures (TLS); these ectopic lymphoid follicles that can develop tissue-targeted antibodies have recently been described in the MRL/lpr lupus mouse strain, a classic model for studying NPSLE. The brains of MRL/lpr mice show a significant increase of CXCL13, an important chemokine in lymphoid follicle formation and retention that may also play a role in the disease progression of NPSLE. The aim of the present study was to inhibit CXCL13 and examine the effect of this intervention on lymphoid formation and the development of neurobehavioral manifestations in lupus mice. Female MRL/lpr mice were injected with an anti-CXCL13 antibody, an IgG1 isotype-matched antibody, or PBS either three times a week for 12 weeks intraperitoneally (IP) starting at 6-8 weeks of age, or continuously intracerebroventricularly (ICV) with an osmotic pump over a two-week period starting at 15 weeks of age. Cognitive dysfunction and depression-like behavior were assessed at the end of treatment. When treatment was delivered IP, anti-CXCL13 treated mice showed significant improvement in cognitive function when compared to control treated mice. Depression-like behavior was attenuated as well. Furthermore, mice that received anti-CXCL13 by the ICV route showed similar beneficial effects. However, the extent of lymphocyte infiltration into the brain and the general composition of the aggregates were not substantively changed by anti-CXCL13 irrespective of the mode of administration. Nevertheless, analysis of brain gene expression in anti-CXCL13 treated mice showed significant differences in key immunological and neuro-inflammatory pathways that most likely explained the improvement in the behavioral phenotype. Our results indicate that CXCL13 affects the behavioral manifestations in the MRL/lpr strain and is important to the pathogenesis of murine NPSLE, suggesting it as a potential therapeutic target.

The Association of Illness Uncertainty and Hope With Depression and Anxiety Symptoms in Women With Systemic Lupus Erythematosus: A Cross-sectional Study of Psychological Distress in Systemic Lupus Erythematosus Women

BACKGROUND

Depression and anxiety are commonly observed psychological symptoms in patients diagnosed with systemic lupus erythematosus (SLE). This study aimed to explore the possible factors that influence depression and anxiety symptoms development in SLE women.

METHODS

This cross-sectional study was conducted between October 2017 and December 2018 in Liaoning, China. Questionnaires including Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, Mishel Uncertainty in Illness Scale for Adults, and Herth Hope Scale were completed by 205 participants. Factors related to depression and anxiety were examined using hierarchical multiple regression analysis, while the effect of hope was examined using structural equation model.

RESULTS

The prevalence of depression and anxiety symptoms in female SLE patients was 79.5% and 86.8%, respectively. Illness uncertainty was strongly positively correlated with depression and anxiety symptoms. In contrast, hope was negatively associated with depression and anxiety symptoms. Up to 66.6% and 59.4% of the variance explained by all the variables was 66.6% in depression symptoms and 59.4% in anxiety symptoms. Interestingly, hope was able to alter the relationship of illness uncertainty with depression and anxiety symptoms.

CONCLUSIONS

While illness uncertainty can increase depression and anxiety symptoms, hope can reduce these symptoms. Therefore, hope-based targeted interventions should be employed to prevent and treat depression and anxiety symptoms among SLE women.

Neuropsychiatric disorders: An immunological perspective

Neuropsychiatric diseases have traditionally been studied from brain, and mind-centric perspectives. However, mounting epidemiological and clinical evidence shows a strong correlation of neuropsychiatric manifestations with immune system activation, suggesting a likely mechanistic interaction between the immune and nervous systems in mediating neuropsychiatric disease. Indeed, immune mediators such as cytokines, antibodies, and complement proteins have been shown to affect various cellular members of the central nervous system in multitudinous ways, such as by modulating neuronal firing rates, inducing cellular apoptosis, or triggering synaptic pruning. These observations have in turn led to the exciting development of clinical therapies aiming to harness this neuro-immune interaction for the treatment of neuropsychiatric disease and symptoms. Besides the clinic, important theoretical fundamentals can be drawn from the immune system and applied to our understanding of the brain and neuropsychiatric disease. These new frameworks could lead to novel insights in the field and further potentiate the development of future therapies to treat neuropsychiatric disease.

A Selective Neutraligand for CXCL12/SDF-1α With Beneficial Regulatory Functions in MRL/Lpr Lupus Prone Mice

Dysregulation of CXCL12/SDF-1-CXCR4/CD184 signaling is associated with inflammatory diseases and notably with systemic lupus erythematosus. Issued from the lead molecule chalcone-4, the first neutraligand of the CXCL12 chemokine, LIT-927 was recently described as a potent analogue with improved solubility and stability. We aimed to investigate the capacity of LIT-927 to correct immune alterations in lupus-prone MRL/lpr mice and to explore the mechanism of action implemented by this small molecule in this model. We found that in contrast to AMD3100, an antagonist of CXCR4 and agonist of CXCR7, LIT-927 reduces the excessive number of several B/T lymphocyte subsets occurring in the blood of sick MRL/lpr mice (including CD3⁺/CD4^-/CD8^-/B220⁺ double negative T cells). In vitro, LIT-927 downregulated the overexpression of several activation markers on splenic MRL/lpr lymphocytes. It exerted effects on the CXCR4 pathway in MRL/lpr CD4⁺ T spleen cells. The results underline the importance of the CXCL12/CXCR4 axis in lupus pathophysiology. They indicate that neutralizing CXCL12 by the neutraligand LIT-927 can attenuate hyperactive lymphocytes in lupus. This mode of intervention might represent a novel strategy to control a common pathophysiological mechanism occurring in inflammatory diseases.

Accumulation of Senescent Neural Cells in Murine Lupus With Depression-Like Behavior

Neuropsychiatric manifestations targeting the central, peripheral, and autonomic nervous system are common in systemic lupus erythematosus (SLE); collectively, these symptoms are termed neuropsychiatric SLE (NPSLE). Among a wide variety of neuropsychiatric symptoms, depression is observed in about 24-39% of SLE patients. Several cytokines and chemokines have been identified as biomarkers or therapeutic targets of NPSLE; in particular, the levels of type 1 interferons, TNFs, and IL-6 are elevated in SLE patient's cerebrospinal fluid (CSF), and these factors contribute to the pathology of depression. Here, we show that senescent neural cells accumulate in the hippocampal cornu ammonis 3 (CA3) region in MRL/lpr SLE model mice with depressive behavior. Furthermore, oral administration of fisetin, a senolytic drug, reduced the number of senescent neural cells and reduced depressive behavior in the MRL/lpr mice. In addition, transcription of several senescence and senescence-associated secretory phenotype (SASP) factors in the hippocampal region also decreased after fisetin treatment in the MRL/lpr mice. These results indicate that the accumulation of senescent neural cells in the hippocampus plays a role in NPSLE pathogenesis, and therapies targeting senescent cells may represent a candidate approach to treat NPSLE.

Association of serum neurofilament light chain levels and neuropsychiatric manifestations in systemic lupus erythematosus

Background:

The aim was to evaluate the diagnostic potential of serum neurofilament light chain (sNfL) measurements in patients with neuropsychiatric systemic lupus erythematosus (NPSLE).

Methods:

sNfL levels were determined by single molecule array assay in a retrospective cross-sectional cohort of 144 patients with systemic lupus erythematosus (SLE). After log-transformation of sNfL levels, mean sNfL levels were compared between NPSLE patients and SLE patients without neuropsychiatric disease using Student’s t test. Furthermore, the association of different neuropsychiatric manifestations with sNfL levels was assessed using a one-way analysis of variance (ANOVA) with post hoc analysis. Associations of sNfL with clinical and laboratory parameters were assessed by correlation and multiple linear regression analysis.

Results:

NPSLE patients (n = 69) had significantly higher sNfL levels than SLE patients without neuropsychiatric disease manifestations (n = 75; mean difference: 0.13, 95% CI: 0.04–0.22, p = 0.006). With regard to the category of NPSLE manifestation, mean sNfL levels were only increased in NPSLE patients with focal central nervous system (CNS) involvement (n = 45; mean difference: 0.16, 95% CI: 0.02–0.30, p = 0.019), whereas mean sNfL levels of NPSLE patients with diffuse CNS and peripheral nervous system involvement did not differ from those of SLE patients without neuropsychiatric manifestations. Age and serum creatinine concentrations were identified as relevant contributors to sNfL levels.

Conclusion:

sNfL is a promising, easily accessible biomarker for neuropsychiatric involvement in SLE patients and might therefore complement the diagnostic workup of SLE patients with suspected involvement of the nervous system.

Neuropsychiatric Systemic Lupus Erythematosus: A 2021 Update on Diagnosis, Management, and Current Challenges

Patients with systemic lupus erythematosus (SLE) experience neuropsychiatric symptoms. The term neuropsychiatric SLE (NPSLE) is a generic term that refers to a series of neurological and psychiatric symptoms directly related to SLE. In approximately 30% of patients with neuropsychiatric symptoms, SLE is the primary cause (NPSLE), and symptoms manifest more frequently around SLE onset. Neurovascular and psychotic conditions can also lead to NPSLE. Pathogenesis of NPSLE is implicated in both neuroinflammatory and ischemic mechanisms, and it is associated with high morbidity and mortality. After diagnosing and assigning causality, NPSLE treatment is individualized according to the type of neuropsychiatric manifestations, type of the predominant pathway, activity of SLE, and severity of the clinical manifestations. There are many problems to be addressed with regards to the diagnosis and management of NPSLE. Controlled clinical trials provide limited guidance for management, and observational cohort studies support symptomatic, antithrombotic, and immunosuppressive agents. The purpose of this review was to provide a detailed and critical review of the literature on the pathophysiology, diagnosis, and treatment of NPSLE. This study aimed to identify the shortcoming in diagnostic biomarkers, novel therapies against NPSLE, and additional research needs.

Lack of Association between Serum Interleukin-23 and Interleukin-27 Levels and Disease Activity in Patients with Active Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by the production of multiple autoantibodies, resulting in tissue and organ damage. Recent studies have revealed that interleukin-23 (IL-23) and interleukin-27 (IL-27) may be therapeutically relevant in selected SLE manifestations. This study aimed to identify associations between serum IL-27 and IL-23 levels and disease activity in Polish patients with different manifestations of SLE: neuropsychiatric lupus (NPSLE), and lupus nephritis (LN). Associations between interleukin levels and oligo-specific antibodies against double-stranded DNA (dsDNA), dose of glucocorticoids, and type of treatment were also analyzed. An enzyme-linked immunosorbent assay was used to assess anti-dsDNA antibodies and analyze the serum concentration of IL-27 and IL-23 from 72 patients aged 19-74 years with confirmed active SLE. Disease activity was measured using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI 2-K). No significant correlations between interleukin levels and SLEDAI score, anti-dsDNA, corticosteroid dose, or type of treatment were noted. Patients with NPSLE and LN presented the highest median scores of SLEDAI.

Association of elevated serum soluble CD226 levels with the disease activity and flares of systemic lupus erythematosus

CD226 is an activating receptor expressed on the cell surface of natural killer cells and T cells. Although CD226 polymorphism is known to be involved in systemic lupus erythematosus (SLE), the involvement of soluble CD226 (sCD226) in SLE is still unknown. In the present study, we measured serum sCD226 levels using an enzyme-linked immunosorbent assay in 58 SLE patients and 33 healthy controls (HCs) and evaluated their associations with SLE Disease Activity Index 2000 (SLEDAI-2K), clinical manifestations, laboratory data, and the cumulative probability of flare. Serum sCD226 levels showed no significant differences between SLE patients and HCs. However, sCD226 levels were significantly elevated in active SLE patients with a SLEDAI-2K score of ≥ 20 compared with HCs. In SLE patients, sCD226 levels were significantly correlated with SLEDAI-2K scores and anti-dsDNA antibody titers. Moreover, the cumulative probability of flare was markedly higher in patients with high sCD226 than in those with low sCD226. In patients with neuropsychiatric involvement, sCD226 levels were elevated and reflected neuropsychiatric disease activity. These findings indicate that serum sCD226 levels are associated with disease activity and flares of SLE. Thus, it may be a useful biomarker for SLE, and its monitoring allows for more precise SLE management.

Role of sphingosine-1-phosphate mediated signalling in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a highly prevalent autoimmune disease characterized by the malfunction of the immune system and the persistent presence of an inflammatory environment. Multiple organs can be affected during SLE, leading to heterogeneous manifestations, which eventually result in the death of patients. Due to the lack of understanding regarding the pathogenesis of SLE, the currently available treatments remain suboptimal. Sphingosine-1-phosphate (S1P) is a central bioactive lipid of sphingolipid metabolism, which serves a pivotal role in regulating numerous physiological and pathological processes. As a well-recognized regulator of lymphocyte trafficking, S1P has been shown to be closely associated with autoimmune diseases, including SLE. Importantly, S1P levels have been found to be elevated in patients with SLE. In murine models of lupus, the increased levels of S1P also contribute to disease activity and organ impairment. Moreover, data from several studies also support the hypothesis that S1P receptors and its producer-sphingosine kinases (SPHK) may serve as the potential targets for the treatment of SLE and its co-morbidities. Given the significant success that intervening with S1P signaling has achieved in treating multiple sclerosis, further exploration of its role in SLE is necessary. Therefore, the aim of the present review is to summarize the recent advances in understanding the potential mechanism by which S1P influences SLE, with a primary focus on its role in immune regulation and inflammatory responses.

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

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

Clinical and Immunological Biomarkers for Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is characterized by immune system dysfunction and is clinically heterogeneous, exhibiting renal, dermatological, neuropsychiatric, and cardiovascular symptoms. Clinical and physiological assessment is usually inadequate for diagnosing and assessing pathophysiological processes in SLE. Clinical and immunological biomarkers could play a critical role in improving diagnosis, assessment, and ultimately, control of SLE. This article reviews clinical and immunological biomarkers that could diagnose and monitor disease activity in SLE, with and without organ-specific injury. In addition, novel SLE biomarkers that have been discovered through “omics” research are also reviewed.

Brain white matter extracellular free-water increases are related to reduced neurocognitive function in systemic lupus erythematosus

OBJECTIVES

Brain white matter (WM) microstructural changes evaluated by diffusion MRI were well documented in patients with systemic lupus erythematosus (SLE). Yet, conventional diffusion tensor imaging technique fails to differentiate WM changes that originate from tissue alterations from those due to increased extracellular free water (FW) related to neuroinflammation, microvascular disruption, atrophy, or other extracellular processes. Here, we sought to delineate changes in WM tissue microstructure and extracellular FW volume and examine their relationships with neurocognitive function in SLE patients.

METHODS

Twenty SLE patients (16 females, aged 36.0±10.6) without clinically-overt neuropsychiatric manifestation and 61 healthy controls (HC) (29 females, aged 29.2±9.4) underwent diffusion MRI and computerized neuropsychological assessments cross-sectionally. The FW imaging method was applied to compare microstructural tissue changes and extracellular FW volume of the brain WM between SLE patients and HC. Association between extracellular FW changes and neurocognitive performance was studied.

RESULTS

SLE patients had higher WM extracellular FW compared to HC (family-wise-error-corrected p < 0.05) while no group difference was found in FW-corrected tissue compartment and structural connectivity metrics. Extracellular FW increases in SLE patients were associated with poorer neurocognitive performance that probed sustained attention (p = 0.022) and higher cumulative glucocorticoid dose (p = 0.0041). Such findings remained robust after controlling for age, gender, IQ, and total WM volume.

CONCLUSIONS

The association between WM extracellular FW increases and reduced neurocognitive performance suggest possible microvascular degradation and/or neuroinflammation in SLE patients with clinically-inactive disease. The mechanistic impact of cumulative glucocorticoids on WM FW deserves further evaluation.

Cognitive Dysfunction in Systemic Lupus Erythematosus: Immunopathology, Clinical Manifestations, Neuroimaging and Management

Cognitive dysfunction (CD) is a common yet often clinically subtle manifestation that considerably impacts the health-related quality of life in patients with systemic lupus erythaematosus (SLE). Given the inconsistencies in CD assessment and challenges in its attribution to SLE, the reported prevalence of CD differs widely, ranging from 3 to 88%. The clinical presentation of CD in SLE is non-specific and may manifest concurrently with overt neuropsychiatric illness such as psychosis or mood disorders or as isolated impairment of attention, working memory, executive dysfunction or processing speed. Despite the lack of standardized and sensitive neuropsychological tests and validated diagnostic biomarkers of CD in SLE, significant progress has been made in identifying pathogenic neural pathways and neuroimaging. Furthermore, several autoantibodies, cytokines, pro-inflammatory mediators and metabolic factors have been implicated in the pathogenesis of CD in SLE. Abrogation of the integrity of the blood-brain barrier (BBB) and ensuing autoantibody-mediated neurotoxicity, complement and microglial activation remains the widely accepted mechanism of SLE-related CD. Although several functional neuroimaging modalities have consistently demonstrated abnormalities that correlate with CD in SLE patients, a consensus remains to be reached as to their clinical utility in diagnosing CD. Given the multifactorial aetiology of CD, a multi-domain interventional approach that addresses the risk factors and disease mechanisms of CD in a concurrent fashion is the favourable therapeutic direction. While cognitive rehabilitation and exercise training remain important, specific pharmacological agents that target microglial activation and maintain the BBB integrity are potential candidates for the treatment of SLE-related CD.

Anxiety and depression severity in neuropsychiatric SLE are associated with perfusion and functional connectivity changes of the frontolimbic neural circuit: a resting-state f(unctional) MRI study

OBJECTIVE

To examine the hypothesis that perfusion and functional connectivity disturbances in brain areas implicated in emotional processing are linked to emotion-related symptoms in neuropsychiatric SLE (NPSLE).

METHODS

Resting-state fMRI (rs-fMRI) was performed and anxiety and/or depression symptoms were assessed in 32 patients with NPSLE and 18 healthy controls (HC). Whole-brain time-shift analysis (TSA) maps, voxel-wise global connectivity (assessed through intrinsic connectivity contrast (ICC)) and within-network connectivity were estimated and submitted to one-sample t-tests. Subgroup differences (high vs low anxiety and high vs low depression symptoms) were assessed using independent-samples t-tests. In the total group, associations between anxiety (controlling for depression) or depression symptoms (controlling for anxiety) and regional TSA or ICC metrics were also assessed.

RESULTS

Elevated anxiety symptoms in patients with NPSLE were distinctly associated with relatively faster haemodynamic response (haemodynamic lead) in the right amygdala, relatively lower intrinsic connectivity of orbital dlPFC, and relatively lower bidirectional connectivity between dlPFC and vmPFC combined with relatively higher bidirectional connectivity between ACC and amygdala. Elevated depression symptoms in patients with NPSLE were distinctly associated with haemodynamic lead in vmPFC regions in both hemispheres (lateral and medial orbitofrontal cortex) combined with relatively lower intrinsic connectivity in the right medial orbitofrontal cortex. These measures failed to account for self-rated, milder depression symptoms in the HC group.

CONCLUSION

By using rs-fMRI, altered perfusion dynamics and functional connectivity was found in limbic and prefrontal brain regions in patients with NPSLE with severe anxiety and depression symptoms. Although these changes could not be directly attributed to NPSLE pathology, results offer new insights on the pathophysiological substrate of psychoemotional symptomatology in patients with lupus, which may assist its clinical diagnosis and treatment.

Cognitive Impairment in SLE: Mechanisms and Therapeutic Approaches

A wide range of patients with systemic lupus erythematosus (SLE) suffer from cognitive dysfunction (CD) which severely impacts their quality of life. However, CD remains underdiagnosed and poorly understood. Here, we discuss current findings in patients and in animal models. Strong evidence suggests that CD pathogenesis involves known mechanisms of tissue injury in SLE. These mechanisms recruit brain resident cells, in particular microglia, into the pathological process. While systemic immune activation is critical to central nervous system injury, the current focus of therapy is the microglial cell and not the systemic immune perturbation. Further studies are critical to examine additional potential therapeutic targets and more specific treatments based on the cause and progress of the disease.

Quantitative susceptibility mapping in the thalamus and basal ganglia of systemic lupus erythematosus patients with neuropsychiatric complaints

Systemic lupus erythematosus (SLE) is an auto-immune disease characterized by multi-organ involvement. Although uncommon, central nervous system involvement in SLE, termed neuropsychiatric SLE (NPSLE), is not an exception. Current knowledge on underlying pathogenic mechanisms is incomplete, however, neuroinflammation is thought to play a critical role. Evidence from neurodegenerative diseases and multiple sclerosis suggests that neuroinflammation is correlated with brain iron accumulation, making quantitative susceptibility mapping (QSM) a potential hallmark for neuroinflammation in vivo. This study assessed susceptibility values of the thalamus and basal ganglia in (NP)SLE patients and further investigated the in vivo findings with histological analyses of postmortem brain tissue derived from SLE patients. We used a 3T MRI scanner to acquire single-echo T2*-weighted images of 44 SLE patients and 20 age-matched healthy controls. Of the 44 patients with SLE, all had neuropsychiatric complaints, of which 29 were classified as non-NPSLE and 15 as NPSLE (seven as inflammatory NPSLE and eight as ischemic NPSLE). Mean susceptibility values of the thalamus, caudate nucleus, putamen, and globus pallidus were calculated. Formalin-fixed paraffin-embedded post-mortem brain tissue including the putamen and globus pallidus of three additional SLE patients was obtained and stained for iron, microglia and astrocytes. Susceptibility values of SLE patients and age-matched controls showed that iron levels in the thalamus and basal ganglia were not changed due to the disease. No subgroup of SLE showed higher susceptibility values. No correlation was found with disease activity or damage due to SLE. Histological examination of the post-mortem brain showed no increased iron accumulation. Our results suggest that neuroinflammation in NPSLE does not necessarily go hand in hand with iron accumulation, and that the inflammatory pathomechanism in SLE may differ from the one observed in neurodegenerative diseases and in multiple sclerosis.

Suppressor of cytokine signaling-1 mimetic peptides attenuate lymphocyte activation in the MRL/lpr mouse autoimmune model

Autoimmune diseases are driven largely by a pathogenic cytokine milieu produced by aberrantly activated lymphocytes. Many cytokines, including interferon gamma (IFN-γ), utilize the JAK/STAT pathway for signal propagation. Suppressor of Cytokine Signaling-1 (SOCS1) is an inducible, intracellular protein that regulates IFN-γ signaling by dampening JAK/STAT signaling. Using Fas deficient, MRL/MpJ-Faslpr/J (MRL/lpr) mice, which develop lupus-like disease spontaneously, we tested the hypothesis that a peptide mimic of the SOCS1 kinase inhibitory region (SOCS1-KIR) would inhibit lymphocyte activation and modulate lupus-associated pathologies. Consistent with in vitro studies, SOCS1-KIR intraperitoneal administration reduced the frequency, activation, and cytokine production of memory CD8+ and CD4+ T lymphocytes within the peripheral blood, spleen, and lymph nodes. In addition, SOCS1-KIR administration reduced lymphadenopathy, severity of skin lesions, autoantibody production, and modestly reduced kidney pathology. On a cellular level, peritoneal SOCS1-KIR administration enhanced Foxp3 expression in total splenic and follicular regulatory T cells, reduced the effector memory/naïve T lymphocyte ratio for both CD4+ and CD8+ cells, and reduced the frequency of GL7+ germinal center enriched B cells. Together, these data show that SOCS1-KIR treatment reduced auto-reactive lymphocyte effector functions and suggest that therapeutic targeting of the SOCS1 pathway through peptide administration may have efficacy in mitigating autoimmune pathologies.

Psychosis in Systemic Lupus Erythematosus (SLE): 40-year experience of a specialist centre

Objectives

The long-term outcome of psychosis in association with systemic lupus erythematosus (SLE) has been insufficiently characterised. We used a specialist centre cohort of patients with SLE and psychosis to investigate their clinical outcome and phenotypic and laboratory characteristics.

Methods

Retrospective cohort study of 709 SLE patients seen at a specialist centre between January 1978 and November 2018. Clinical, biochemical and immunological characteristics (Bonferroni corrected), and serum neuronal surface antibody profile using novel cell-based assays, were compared between patients with and without psychosis.

Results

Eighteen (18/709, 2.5%) patients developed lupus psychosis over a mean ± SD of 17.5 ± 11.0 years follow-up. Psychosis fully remitted in 66.7% (12/18) with a combination of antipsychotic (in 38.9%) and immunosuppressive therapy (methylprednisolone 72.2%, cyclophosphamide 55.6%, rituximab 16.7%, plasma exchange 27.8%, prednisolone 50%). Patients who developed lupus psychosis may be more likely to have anti-RNP antibodies (50.0% vs 26.5%) and less likely to have anti-cardiolipin antibodies (5.6% vs 30.0%), but this was not significant in our small sample. Neuronal surface autoantibody tests found GABA_BR autoantibodies in 3/10 (30.0%) lupus psychosis patients compared with only 3/27 (11.1%) in age- and sex-matched SLE controls using fixed cell-based assays (P =0.114). However, GABA_BR antibodies were not replicated using a live cell-based assay. NMDAR-antibodies were not detected with fixed or live cell assays in any samples.

Conclusion

Lupus psychosis is rare but treatable. In this rare sample of eighteen patients from a 40-year cohort, no significant biomarker was found, but some preliminary associations warrant further exploration in a larger multicentre analysis.

Advanced neuroimaging in neuropsychiatric systemic lupus erythematosus

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.

The management of neuropsychiatric lupus in the 21st century: still so many unmet needs?

Neuropsychiatric (NP) events occur in the majority of patients with SLE and predominantly affect the CNS in addition to the peripheral and autonomic systems. Approximately 30% of all NP events are attributable to SLE (NPSLE) and present most frequently around the time of SLE onset. NPSLE is associated with increased morbidity and mortality and the proposed pathogenesis includes both ischaemic and neuroinflammatory mechanisms. Following diagnosis and causal attribution, the treatment of NPSLE is tailored to the type of NP event, the predominant putative pathogenic pathway and the activity and severity of the clinical event. There is a dearth of controlled clinical trials to guide management, but therapeutic options include symptomatic, antithrombotic and immunosuppressive agents that are supported by observational cohort studies. Our objective was to review what is currently known about NPSLE and to identify deficiencies in diagnostic biomarkers, novel therapies and clinical trials for this manifestation of SLE.

Clinical Features and Outcomes of Neuropsychiatric Systemic Lupus Erythematosus in China

Objective

To identify the clinical characteristics, magnetic resonance imaging (MRI) results, and prognostic factors of neuropsychiatric (NP) systemic lupus erythematosus (SLE; NPSLE) in a relatively large patient series in China.

Methods

Data of patients with NPSLE at Peking Union Medical College Hospital (PUMCH) were collected retrospectively from June 2012 to June 2016. NPSLE patients were compared with 220 non-NPSLE patients. Survival rates were evaluated using the Kaplan-Meier curves, log-rank test, and Cox proportional hazards modeling. Cranial MRI results were also studied.

Results

Of the 194 included patients, sixteen subtypes of NPSLE were identified, and the most common manifestations were seizure (36.6%), acute confusional state (25.3%), and cerebral vascular disease (15.5%). Compared with the non-NPSLE group, NPSLE patients were significantly more likely to have typical lupus symptoms, higher Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores (P = 0.002), and positive rate of anti-ribosomal P protein antibodies (P = 0.008). Patients with seizure were more likely to have higher SLEDAI-2K scores and positive anti-β2GP1 than non-NPSLE patients. Sixteen patients died during follow-up. The most common cause of death was infection (37.5%). NPSLE significantly decreased survival rates of SLE patients. Patients with elevated serum creatinine (P = 0.001), hypocomplementemia (P = 0.031), and SLEDAI - 2K scores ≥ 15 (P = 0.014) had shorter survival periods. Eighty-two patients underwent detailed cranial MRI analysis; of these, 50 (61.0%) had abnormal results. Small vessel disease was the most common abnormal finding, followed by inflammatory-like lesions and large vessel disease.

Conclusions

High disease activity and positive rate of anti-ribosomal P protein antibodies may be risk factors for NPSLE. NPSLE decreases survival rates of SLE patients. Renal insufficiency and high disease activity are predictive of poor prognoses for NPSLE patients.

Time Course of Metabolic Alterations Associated with the Progression of Systemic Lupus Erythematosus in MRL/lpr Mice Based on GC/MS

Exploring the dynamic changes of metabolites and metabolic pathways during the development of the disease can help to further understand the etiology and pathogenesis of systemic lupus erythematosus (SLE). In this study, serum metabolomics based on gas chromatography/mass spectrometry (GC/MS) was employed to investigate the metabolic alterations at different stages of SLE using lupus-prone mice (MRL/lpr) of 9, 11, and 13 weeks of age. Multivariate statistical analysis was performed to view the alterations of metabolic profiles between MRL/lpr mice and age-matched C57BL/6 mice, and t-test and fold change criteria were used to identify differential metabolites at each stage. 11 changed metabolites were found in MRL/lpr mice at 9 weeks of age, which were mainly involved in the tricarboxylic acid (TCA) cycle, glycolysis, and butanoate metabolism; with the increase of week age, the TCA cycle was still disturbed, and the biosynthesis of fatty acids was significantly upregulated since 11 weeks of age; in addition, urea, urate, and indole-3-lactate were increased at 13 weeks of age. We found a time course of metabolic alterations in MRL/lpr mice, which may be related to the progression of SLE. These findings could provide a reference for studying the mechanism of SLE and judging the pathological stage and severity of the disease. The MS data have been deposited in Mendeley (https://www.mendeley.com/).

Systemic lupus erythematosus: The search for the ideal biomarker

During the last decades, there has been an increased interest in the discovery and validation of biomarkers that reliably reflect specific aspects of lupus. Although many biomarkers have been developed, few of them have been validated and used in clinical practice, but with unsatisfactory performances. Thus, there is still a need to rigorously validate many of these novel promising biomarkers in large-scale longitudinal studies and also identify better biomarkers not only for lupus diagnosis but also for monitoring and predicting upcoming flares and response to treatment. Besides serological biomarkers, urinary and cerebrospinal fluid biomarkers have emerged for assessing both renal and central nervous system involvement in systemic lupus erythematosus, respectively. Also, novel omics techniques help us to understand the molecular basis of the disease and also allow the identification of novel biomarkers which may be potentially useful for guiding new therapeutic targets.

Microglial responses to peripheral type 1 interferon

BACKGROUND

Interferon α (IFNα) is a cytokine whose production is increased endogenously in response to viral infection and in autoimmune diseases such as systemic lupus erythematosus (SLE). An elevated IFNα signature has been associated with clinically observed neuro-behavioural deficits such as mild cognitive impairment, fatigue, depression and psychosis in these diseases. However, the mechanisms underlying these neuropsychiatric symptoms remain largely unknown, and it is as yet unclear how IFNα signalling might influence central nervous system (CNS) function. Aberrant microglia-mediated synaptic pruning and function has recently been implicated in several neurodegenerative and neuropsychiatric diseases, but whether and how IFNα modulates these functions are not well defined.

METHODS

Using a model of peripheral IFNα administration, we investigated gene expression changes due to IFNAR signalling in microglia. Bulk RNA sequencing on sorted microglia from wild type and microglia-specific Ifnar1 conditional knockout mice was performed to evaluate IFNα and IFNAR signalling-dependent changes in gene expression. Furthermore, the effects of IFNα on microglia morphology and synapse engulfment were assessed, via immunohistochemistry and flow cytometry.

RESULTS

We found that IFNα exposure through the periphery induces a unique gene signature in microglia that includes the expected upregulation of multiple interferon-stimulated genes (ISGs), as well as the complement component C4b. We additionally characterized several IFNα-dependent changes in microglial phenotype, including expression of CD45 and CD68, cellular morphology and presynaptic engulfment, that reveal subtle brain region-specific differences. Finally, by specifically knocking down expression of IFNAR1 on microglia, we show that these changes are largely attributable to direct IFNAR signalling on microglia and not from indirect signalling effects through other CNS parenchymal cell types which are capable of IFNα-IFNAR signal transduction.

CONCLUSIONS

Peripheral IFNα induces unique genetic and phenotypic changes in microglia that are largely dependent on direct signalling through microglial IFNAR. The IFNα-induced upregulation of C4b could play important roles in the context of aberrant synaptic pruning in neuropsychiatric disease.

Lupus animal models and neuropsychiatric implications

Systemic lupus erythematosus (SLE) that involves neurological complications is known as neuropsychiatric systemic lupus erythematosus (NPSLE). Research in humans is difficult due to the disease's great heterogeneity. Animal models are a resource for new discoveries. In this review, we examine experimental models of lupus that present neuropsychiatric manifestations. Spontaneous animal models such as NZB/W F1 and MRL/lpr are commonly used in NPSLE research; these models present few SLE symptoms compared to induced animal models, such as pristane-induced lupus (PIL). The PIL model is known to present eight of the main clinical and laboratory manifestations of SLE described by the American College of Rheumatology. Many cytokines associated with NPSLE are expressed in the PIL model, such as IL-6, TNF-α, and IFN. However, to date, NPSLE manifestations have been poorly studied in the PIL model. In this review article, we discuss whether the PIL model can mimic neuropsychiatric manifestations of SLE. Key Points • PIL model have a strong interferon signature. • Animals with PIL express learning and memory deficit.

Protein A immunoadsorption combination with immunosuppressive therapy improves neuropsychiatric systemic lupus erythematosus: A case report

We described protein A immunoadsorption combination with immunosuppressive treatment improved rapidly a patient with Neuropsychiatric systemic lupus erythematosus.

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.

Probable Autoimmune Depression in a Patient With Multiple Sclerosis and Antineuronal Antibodies

BACKGROUND

In a subgroup of patients with mood disorders, clear-cut organic disorders are responsible for depressive symptoms (e.g., autoimmune diseases such as multiple sclerosis or systemic lupus erythematosus). In these cases, an organic affective disorder can be diagnosed.

CASE PRESENTATION

The authors present the case of a 59-year-old male patient who developed a severe depressive episode over approximately 6 months and was, therefore, admitted to the hospital. In retrospect, he reported that, at age 39, he suffered from self-limiting sensory disturbances and muscle weakness in both legs. The current magnetic resonance imaging of his brain showed several conspicuous FLAIR-hyperintense supratentorial white matter lesions compatible with chronic inflammatory brain disease. Imaging of the spinal axis revealed no clear spinal lesions. Cerebrospinal fluid (CSF) analyses showed CSF-specific oligoclonal bands. Therefore, multiple sclerosis was diagnosed. Further CSF analyses, using tissue-based assays with indirect immunofluorescence on unfixed murine brain tissue, revealed a (peri-)nuclear signal and a strong neuritic signal of many neurons, especially on granule cells in the cerebellum, hippocampus, and olfactory bulb, as well as in the corpus callosum. Additionally, antinuclear antibody (ANA) titers of 1:12,800 and a lymphopenia were detected in blood tests. Further system clarification showed no suspicion of rheumatic or oncological disease. Anti-inflammatory treatment led to rapid and sustained improvement.

CONCLUSION

The present patient suffered from a probable "autoimmune depression" in the context of newly diagnosed multiple sclerosis with typical MRI and CSF pathologies, alongside mild concomitant latent systemic autoimmune process (with high-titer ANAs and lymphopenia) and unknown antineuronal antibodies. The case report illustrates that a depressive syndrome suggestive of primary idiopathic depressive disorder may be associated with an autoimmune brain involvement. The detection of such organic affective disorders is of high clinical relevance for affected patients, as it enables alternative and more causal treatment approaches.

Using the Mouse to Model Human Diseases: Cognitive Impairment in Systemic Lupus Erythematosus

In this 2020 Dunlop-Dottridge Lecture, the authors discuss cognitive impairment (CI), one of the most prevalent neuropsychiatric syndromes in systemic lupus erythematosus (SLE). Patients often report CI as the most bothersome disease-related manifestation, with a great effect on their quality of life. Nevertheless, studies focusing on CI remain scarce and no effective targeted therapy has been identified. We herein present murine models of CI in SLE with insights into the pathogenesis of this condition as well as the role of the renin angiotensin system in microglial activation. We will discuss the role of neuroimaging as a useful objective assessment tool, describing our experience in previous and ongoing clinical trials of CI in patients with SLE.

Kynurenines in the Pathogenesis of Multiple Sclerosis: Therapeutic Perspectives

Over the past years, an increasing amount of evidence has emerged in support of the kynurenine pathway’s (KP) pivotal role in the pathogenesis of several neurodegenerative, psychiatric, vascular and autoimmune diseases. Different neuroactive metabolites of the KP are known to exert opposite effects on neurons, some being neuroprotective (e.g., picolinic acid, kynurenic acid, and the cofactor nicotinamide adenine dinucleotide), while others are toxic to neurons (e.g., 3-hydroxykynurenine, quinolinic acid). Not only the alterations in the levels of the metabolites but also disturbances in their ratio (quinolinic acid/kynurenic acid) have been reported in several diseases. In addition to the metabolites, the enzymes participating in the KP have been unearthed to be involved in modulation of the immune system, the energetic upkeep of neurons and have been shown to influence redox processes and inflammatory cascades, revealing a sophisticated, intertwined system. This review considers various methods through which enzymes and metabolites of the kynurenine pathway influence the immune system, the roles they play in the pathogenesis of neuroinflammatory diseases based on current evidence with a focus on their involvement in multiple sclerosis, as well as therapeutic approaches.

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.

Downregulated miR‑29a promotes B cell overactivation by upregulating Crk‑like protein in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disorder; however, the pathogenesis is not fully understood. Accumulating evidence suggested an important role of microRNAs (miRNA/miR) in autoimmunity. The present study aimed therefore to determine the miRNA expression patterns in the B cells from the peripheral blood of 66 patients with SLE and 10 healthy controls (HCs) by using an Affymetrix GeneChip® miRNA 2.0 array. In addition, next‑generation sequencing was used to obtain the peripheral blood mononuclear cell (PBMC) miRNA profiles from three patients with SLE and three HCs. Candidate miRNAs that were considered to contribute to the pathogenesis of SLE were obtained based on the intersection of miRNA profiles. The analysis revealed a significant downregulation in miR‑29a expression levels in B cells from patients with SLE, which was subsequently verified using reverse transcription‑quantitative PCR. Based on these results, the expression pattern of miR‑29a in SLE was further investigated and its role in the hyperactivity of B cells was determined. miR‑29a inhibitors and mimics were transfected into PBMCs obtained from HCs and patients with SLE, and an ELISA was used to demonstrate that miR‑29a inhibition increased the production of IgG. Bioinformatics analysis predicted Crk‑like protein (CRKL) as a target gene of miR‑29a in patients with SLE. Therefore, CRKL expression levels were compared between patients with SLE and HCs by using western blotting, and its direct transcriptional regulation by miR‑29a was determined using a dual‑luciferase reporter assay. Low expression levels of miR‑29a were revealed to upregulate the expression levels of CRKL in B cells, and the protein expression levels of CRKL in patients with SLE were significantly upregulated compared with the HCs. In conclusion, the results from the present study suggested that miR‑29a may affect IgG antibody secretion in B cells by regulating CRKL, thereby contributing to the development and progression of SLE, which offers a novel candidate target for treatment.

Comparative proteomics analysis of plasma protein in patients with neuropsychiatric systemic lupus erythematosus

Background

The aim of this study was to evaluate serum biomarkers of systemic lupus erythematous (SLE) patients, with and without neuropsychiatric (NP) manifestation by high-resolution proteomic analysis.

Methods

SLE patients with NP (NPSLE, n=9), SLE patients without NP (non-NPSLE, n=9) and healthy controls (HC, n=9) were prospectively enrolled in this study, and their plasma samples were collected and pooled into 3 NPSLE, 3 non-NPSLE and 3 HC samples for discovery profile. The TMT-LC-MS/MS-based proteomics approach was used to identify the differential proteome among the three matched groups, and the data were analyzed by bioinformatics tools, including Gene Ontology (GO) categories, Kyoto Encyclopedia of Genes and Genomes enrichment analysis, to explore canonical pathways and networks involved in the pathogenesis of NPSLE. To validation of differentially expressed proteomics results, four proteins were measured by ELISA.

Results

There were altogether 223 differentially expressed proteins in NPSLE groups compared with healthy controls (HC), of which 96 proteins increased while 127 proteins decreased. Compared with non-NPSLE, there were only 49 differentially expressed proteins in NPSLE groups, of which 37 proteins increased while 12 proteins decreased. The significantly changed pathway that those proteins are involved in was complement and coagulation cascades in NPSLE group compared with health controls. However, we didn't find significantly changed pathway between NPSLE group and non-NPSLE group. Five proteins were found significantly changed in all group-comparisons with consistent tendencies using Venn analysis, including Vitamin D binding protein (VDBP), C-reactive protein (CRP), KRT16, IGHV4-4 and CTRP3. Four proteins including CTRP3, VDBP, PAPPA and TRYP2 were selected to estimate the validity of the proteomics approach by ELISA. The expression levels of CTRP3 and TRYP2 were significantly changed in NPSLE patients compared with either HC or non-NPSLE patients.

Conclusions

Our research has successfully established serum protein profiles of NPSLE and non-NPSLE patients through TMT technology and screened out five proteins significantly changed in group-comparisons with consistent tendencies. The pathway of complement and coagulation cascades may participate in pathogenesis of NPSLE and non-NPSLE.

Physiopathology of pain in systemic erythematosus lupus

Systemic lupus erythematosus is an autoimmune disease that promotes chronic inflammation, with periods of activation and remission. Pain is commonly one of the first symptoms reported by patients with lupus. It interferes with patients' quality of life, leading to a decrease in strength and difficulty in performing daily activities. Given the chronic nature of the disease, the high prevalence of pain and its negative impact on the quality of life of patients with lupus, the present literature review study aims to explain the pathophysiology of pain in systemic lupus erythematosus and the implications of the chronic process and contributing factors. During periods of systemic lupus erythematosus activity, pain is a significant symptom. Despite this, several studies show that severe pain can occur in patients with in mild to moderate disease activity. Also, in the early stages of the disease, the pain may be accentuated by the greater activity of the disease. However, even when advanced disease is under control, there can be comorbidities and accumulated damage that can also cause high levels of pain. This sensitivity is due to the overlap of primary, secondary, and tertiary pain pathologies, which feedback and make this symptom one of the main concerns of patients with lupus. Understanding the pathophysiology of pain in systemic lupus erythematosus, as well as its chronification and contribution factors, is essential to identify effective therapeutic alternatives in these patients at each stage of pain pathology (primary, secondary, and tertiary).

Autoantibodies associated with neuropsychiatric systemic lupus erythematosus: the quest for symptom-specific biomarkers

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that affects multiple organs, including the central nervous system. Neuropsychiatric SLE (NPSLE) is a severe and potentially fatal condition. Several factors including autoantibodies have been implicated in the pathogenesis of NPSLE. However, definitive biomarkers of NPSLE are yet to be identified owing to the complexity of this disease. This is a major barrier to accurate and timely diagnosis of NPSLE. Studies have identified several autoantibodies associated with NPSLE;some of these autoantibodies are well investigated and regarded as symptom-specific. In this review, we discuss recent advances in our understanding of the manifestations and pathogenesis of NPSLE. In addition, we describe representative symptom-specific autoantibodies that are considered to be closely associated with the pathogenesis of NPSLE.

A20/TNFAIP3 heterozygosity predisposes to behavioral symptoms in a mouse model for neuropsychiatric lupus

Background

Neuropsychiatric lupus (NPSLE) refers to the neurological and psychiatric manifestations that are commonly observed in patients with systemic lupus erythematosus (SLE). An important question regarding the pathogenesis of NPSLE is whether the symptoms are caused primarily by CNS-intrinsic mechanisms or develop as a consequence of systemic autoimmunity. Currently used spontaneous mouse models for SLE have already contributed significantly to unraveling how systemic immunity affects the CNS. However, they are less suited when interested in CNS primary mechanisms. In addition, none of these models are based on genes that are associated with SLE. In this study, we evaluate the influence of A20, a well-known susceptibility locus for SLE, on behavior and CNS-associated changes in inflammatory markers. Furthermore, given the importance of environmental triggers for disease onset and progression, the influence of an acute immunological challenge was evaluated.

Methods

Female and male A20 heterozygous mice (A20+/-) and wildtype littermates were tested in an extensive behavioral battery. This was done at the age of 10±2weeks and 24 ​± ​2 weeks to evaluate the impact of aging. To investigate the contribution of an acute immunological challenge, LPS was injected intracerebroventricularly at the age of 10±2weeks followed by behavioral analysis. Underlying molecular mechanisms were evaluated in gene expression assays on hippocampus and cortex. White blood cell count and blood-brain barrier permeability were analyzed to determine whether peripheral inflammation is a relevant factor.

Results

A20 heterozygosity predisposes to cognitive symptoms that were observed at the age of 10 ​± ​2 weeks and 24 ​± ​2 weeks. Young A20+/- males and females showed a subtle cognitive phenotype (10±2weeks) with distinct neuroinflammatory phenotypes. Aging was associated with clear neuroinflammation in female A20+/- mice only. The genetic predisposition in combination with an environmental stimulus exacerbates the behavioral impairments related to anxiety, cognitive dysfunction and sensorimotor gating. This was predominantly observed in females. Furthermore, signs of neuroinflammation were solely observed in female A20+/- mice. All above observations were made in the absence of peripheral inflammation and of changes in blood-brain barrier permeability, thus consistent with the CNS-primary hypothesis.

Conclusions

We show that A20 heterozygosity is a predisposing factor for NPSLE. Further mechanistic insight and possible therapeutic interventions can be studied in this mouse model that recapitulates several key hallmarks of the disease.

Galectin-9 as a biomarker for disease activity in systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by elevated interferon (IFN) signature genes. Galectin-9 (Gal-9) is a β-galactoside-binding lectin that is reportedly useful as a biomarker for IFN gene signatures. In a cross-sectional study of Japanese patients with recent-onset SLE, we aimed to determine whether raised serum Gal-9 levels were associated with the disease activity or organ damage seen in SLE patients.

Methods

The current study included 58 Japanese patients with SLE and 31 age-matched healthy individuals. Disease activity and organ damage were assessed using SLE Disease Activity 2000 (SLEDAI-2K) and Systemic Lupus International Collaborating Clinics (SLICC) damage index. Serum and cerebrospinal fluid (CSF) Gal-9 concentrations were quantified using ELISA. Correlation analyses between Gal-9 and clinical parameters including disease activity were performed.

Results

Serum levels of Gal-9 were significantly increased in patients with SLE compared with the control group (16.6 ng/ml, [interquartile range (IQR); 3.6–59.7] versus 4.74 ng/ml, [IQR; 3.0–9.5], p<0.0001). Gal-9 was significantly correlated with disease activity measures in the SLEDAI-2K. Serum Gal-9 levels were significantly greater in patients with SLE-related organ involvement (23.1 ng/ml, [IQR; 5.1–59.7] versus 12.5ng/ml, [IQR; 3.6–39.0], p = 0.013). Whereas there was no difference in serum levels of CXCL10 or M2BPGi between patients with and without SLE-related organ involvement. Serum levels of Gal-9 were significantly higher in SLE patients with active renal involvement determined by BILAG renal score (A-B) compared to those without active renal involvement (C-E). Whereas there was no significant difference in serum levels of Gal-9 between SLE patients with or without active other organ involvements (neurological or hematological) determined by BILAG score. SLE patients with detectable circulating IFN-α had raised serum Gal-9 levels. Levels of Gal-9 were significantly higher in the CSF from patients with recent-onset neuropsychiatric SLE (NPSLE) than in those from non-SLE controls (3.5 ng/ml, [IQR; 1.0–27.2] versus 1.2 ng/ml, [IQR; 0.9–2.1], p = 0.009).

Conclusions

Gal-9 could be a serologic marker of disease activity and organ involvement in SLE patients. Future studies evaluating the role of Gal-9 in the SLE phenotype may provide insights into SLE pathogenesis.

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.

Neuroimmune crosstalk in the pathophysiology of hypertension

Hypertension is an important risk factor for cardiovascular morbidity and mortality and for events such as myocardial infarction, stroke, heart failure and chronic kidney disease and is a major determinant of disability-adjusted life-years. Despite the importance of hypertension, the pathogenesis of essential hypertension, which involves the complex interaction of several mechanisms, is still poorly understood. Evidence suggests that interplay between bone marrow, microglia and immune mediators underlies the development of arterial hypertension, in particular through mechanisms involving cytokines and peptides, such as neuropeptide Y, substance P, angiotensin II and angiotensin-(1-7). Chronic psychological stress also seems to have a role in increasing the risk of hypertension, probably through the activation of neuroimmune pathways. In this Review, we summarize the available data on the possible role of neuroimmune crosstalk in the origin and maintenance of arterial hypertension and discuss the implications of this crosstalk for recovery and rehabilitation after cardiac and cerebral injuries.

Lysosomes as a therapeutic target

Lysosomes are membrane-bound organelles with roles in processes involved in degrading and recycling cellular waste, cellular signalling and energy metabolism. Defects in genes encoding lysosomal proteins cause lysosomal storage disorders, in which enzyme replacement therapy has proved successful. Growing evidence also implicates roles for lysosomal dysfunction in more common diseases including inflammatory and autoimmune disorders, neurodegenerative diseases, cancer and metabolic disorders. With a focus on lysosomal dysfunction in autoimmune disorders and neurodegenerative diseases - including lupus, rheumatoid arthritis, multiple sclerosis, Alzheimer disease and Parkinson disease - this Review critically analyses progress and opportunities for therapeutically targeting lysosomal proteins and processes, particularly with small molecules and peptide drugs.

Interferon-α exacerbates neuropsychiatric phenotypes in lupus-prone mice

Background

Neuropsychiatric systemic lupus erythaematosus (NP-SLE) is one of the major manifestations of lupus. However, the mechanisms involved in NP-SLE are still largely unknown. The abnormal activation of the type I IFN signalling pathway is involved in SLE pathogenesis and is linked to NP-SLE, but the effect of IFN-α on NP-SLE encephalopathy has not been systematically studied.

Methods

An intravenous injection of Adv-IFN-α (10 mice, 10 × 10⁹ vp) was administered to the IFN-α-treated group, and Adv-ctrl (10 mice, 10 × 10⁹ vp) (ViGene Biosciences, China) was administered to the control group. Gene expression was determined by real-time quantitative polymerase chain reaction (RT-qPCR). Enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies in the serum, and urinary protein levels were measured with a BCA Protein Assay kit. Haematoxylin-eosin (H&E) and periodic acid-Schiff (PAS)-light green staining were used for kidney histology. The elevated plus-maze test, novelty-suppressed feeding assay, open-field test, tail suspension test, social dominance tube test, three-chamber social interaction test, step-down passive avoidance test and novelty Y-maze task were used to assess behaviour.

Results

In this study, we performed a series of behavioural tests to assess the neuropsychiatric phenotypes of IFN-α-treated NZB/NZW F1 mice and found that these mice developed a series of mental disorders such as anxiety-like phenotypes, depression-like phenotypes, deficits in sociability and cognitive impairments, which mimic the neuropsychiatric manifestations of NP-SLE, with a consistent onset and progression.

Conclusions

Our research verified that IFN-α plays a critical role in NP-SLE and provides a comprehensive NP-SLE mouse model for dissecting the mechanisms of NP-SLE and developing novel therapies for intervention.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1985-9) contains supplementary material, which is available to authorized users.

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.

Cognitive Dysfunction in Systemic Lupus Erythematosus: A Case for Initiating Trials

Cognitive dysfunction (CD) is an insidious and underdiagnosed manifestation of systemic lupus erythematosus (SLE) that has a considerable impact on quality of life, which can be devastating. Given the inconsistencies in the modes of assessment and the difficulties in attribution to SLE, the reported prevalence of CD ranges from 5% to 80%. Although clinical studies of SLE-related CD have been hampered by heterogeneous subject populations and a lack of sensitive and standardized cognitive tests or other validated objective biomarkers for CD, there are, nonetheless, strong data from mouse models and from the clinical arena that show CD is related to known disease mechanisms. Several cytokines, inflammatory molecules, and antibodies have been associated with CD. Proposed mechanisms for antibody- and cytokine-mediated neuronal injury include the abrogation of blood-brain barrier integrity with direct access of soluble molecules in the circulation to the brain and ensuing neurotoxicity and microglial activation. No treatments for SLE-mediated CD exist, but potential candidates include agents that inhibit microglial activation, such as angiotensin-converting enzyme inhibitors, or that protect blood-brain barrier integrity, such as C5a receptor blockers. Structural and functional neuroimaging data have shown a range of regional abnormalities in metabolism and white matter microstructural integrity in SLE patients that correlate with CD and could in the future become diagnostic tools and outcome measures in clinical trials aimed at preserving cognitive function in SLE.