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

The Challenge of Neuropsychiatric Systemic Lupus Erythematosus: From Symptoms to Therapeutic Strategies

Systemic lupus erythematosus (SLE) is a chronic autoimmune condition that can seriously impair multiple organs including the nervous system, causing neuropsychiatric SLE (NPSLE), which encompasses a broad range of symptoms. Pathogenesis is not completely understood but is thought to involve inflammatory and vascular pathways. This comprehensive review discusses the complex nature and heterogeneity of NPSLE and the challenges in diagnosis and treatment that result from it. Diagnosis often requires a multidisciplinary approach with multiple assessments, including laboratory testing, imaging, and neuropsychological evaluations. Current treatments focus on managing symptoms through immunosuppressive and anti-thrombotic therapies tailored to the inflammatory or vascular nature of the specific NPSLE manifestations. This paper emphasizes the necessity for interdisciplinary approaches and further research to enhance diagnostic accuracy and treatment effectiveness. It also highlights the importance of understanding the underlying mechanisms of NPSLE to develop more targeted therapies, citing the need for high-quality studies and novel treatment agents.

Neuropsychiatric Systemic Lupus Erythematosus: Molecules Involved in Its Imunopathogenesis, Clinical Features, and Treatment

Systemic lupus erythematosus (SLE) is an idiopathic chronic autoimmune disease that can affect any organ in the body, including the neurological system. Multiple factors, such as environmental (infections), genetic (many HLA alleles including DR2 and DR3, and genes including C4), and immunological influences on self-antigens, such as nuclear antigens, lead to the formation of multiple autoantibodies that cause deleterious damage to bodily tissues and organs. The production of autoantibodies, such as anti-dsDNA, anti-SS(A), anti-SS(B), anti-Smith, and anti-neuronal DNA are characteristic features of this disease. This autoimmune disease results from a failure of the mechanisms responsible for maintaining self-tolerance in T cells, B cells, or both. Immune complexes, circulating antibodies, cytokines, and autoreactive T lymphocytes are responsible for tissue injury in this autoimmune disease. The diagnosis of SLE is a rheumatological challenge despite the availability of clinical criteria. NPSLE was previously referred to as lupus cerebritis or lupus sclerosis. However, these terms are no longer recommended because there is no definitive pathological cause for the neuropsychiatric manifestations of SLE. Currently, the treatment options are primarily based on symptomatic presentations. These include the use of antipsychotics, antidepressants, and anxiolytic medications for the treatment of psychiatric and mood disorders. Antiepileptic drugs to treat seizures, and immunosuppressants (e.g., corticosteroids, azathioprine, and mycophenolate mofetil), are directed against inflammatory responses along with non-pharmacological interventions.

Association between Inflammation and Thrombotic Pathway Link with Pathogenesis of Depression and Anxiety in SLE Patients

As a complication of systemic lupus erythematosus (SLE), the neuropsychiatric form may manifest with neurological and psychiatric symptoms. Diagnosing neuropsychiatric SLE can be challenging due to the heterogeneity of this disease manifestation and the possibilities of investigation. This research aims to identify the possible associations between inflammation and thrombotic biomarkers alongside anxiety and/or depression manifestations in SLE patients. A group of 65 outpatients were investigated regarding the levels of depression, anxiety, disability, quality of life and other specific serum biomarkers linked with inflammation or coagulopathies. The results showed severe depression in eight participants, moderate depression in 22 (33.85%), and 26 (40%) subjects with mild depression. Anxiety was more prevalent within 64 participants (98.46%), while a degree of disability was reported by 52 participants (80%). Quality of life evaluated by EQ5D revealed a medium value of 1.57, and EQ5D VAS health medium value was 57.95 and was correlated with anxiety. A strong positive correlation between depression, anxiety and antibodies associated with anti-cardiolipin and anti beta2 glycoprotein I antibodies, lupus anticoagulant, ICAM-1, low C4 a and anti-ribosomal P antibodies were identified. These data results suggest that autoimmune/inflammatory and ischemic/thrombotic pathways could contribute to depression and anxiety as neuropsychiatric SLE manifestations.

Small molecule compound K-7174 attenuates neuropsychiatric manifestations in lupus-prone mice

The neuropsychiatric manifestations of systemic lupus erythematosus (NPSLE) present significant morbidity and mortality due to frequent non-response or adverse effects of the current clinical drugs. The disruption of the blood-brain barrier (BBB) contributes to inflammatory NPSLE disease progression. K-7174, a highly piperazine-derived compound, inhibits leukocyte adhesion and inflammatory factor expression. The present study aimed to comprehensively assess the treatment effect of neurobehavioral deficits in MRL/lpr mice, a validated neuropsychiatric lupus model. The intraperitoneal injection of K-7174 alleviated lupus-like symptoms and improved cognitive dysfunction in MRL/lpr mice. Also, it significantly attenuated neuronal degeneration and decreased serum albumin deposition in the hippocampus. Furthermore, K-7174 acted directly on the brain microvascular endothelial bEnd.3 cells and reduced the BBB permeability, manifested by inhibiting the activation of brain microvascular endothelial cells and increasing the expression of tight junctions (TJs). Notably, in vitro experiments showed that K-7174 alleviates the decreased ZO1 and Occludin expression in bEnd.3 cells caused by lactate increase, improving cell permeability via the MCT4/NKAP/CREB signaling pathway. These findings suggested that K-7174 mediates the attenuation of NPSLE in MRL/lpr mice, indicating a promising therapeutic strategy for NPSLE.

Autoantibodies against specific post-translationally modified proteins are present in patients with lupus and associate with major neuropsychiatric manifestations

Background

Although autoantibodies are an important hallmark of systemic lupus erythematosus (SLE), most are not specific for SLE or any of its clinical manifestations. Autoantibodies against post-translationally modified (PTM) proteins have been studied extensively in rheumatoid arthritis and associate with disease progression. While PTMs have also been detected in patients with SLE, studies on anti-PTM antibodies remain scarce. We studied the presence of anti-PTM antibodies in SLE and neuropsychiatric SLE (NPSLE), a manifestation that lacks serological markers.

Methods

IgG antibody responses against six PTMs (malondialdehyde–acetaldehyde adducts (MAA), advanced glycation end-products (AGE), carbamylation (CarP), citrullination, acetylation and nitration) were tested using ELISA in sera of 349 patients with SLE (mean age 44±13 years; 87% female) and compared with 108 healthy controls. Levels and positivity were correlated with clinical features and SLE manifestations.

Results

Anti-MAA, anti-AGE and anti-CarP antibodies were more prevalent in SLE compared with controls (MAA: 29% vs 3%, AGE: 18% vs 4%, CarP: 14% vs 5%, all p≤0.0001). Anti-MAA and anti-AGE antibodies correlated with clinical manifestations and serological inflammatory markers. Patients with major NPSLE showed higher positivity of anti-MAA (39% vs 24%, p=0.01) and anti-CarP antibodies (20% vs 11%, p=0.04) than patients without major NPSLE. In addition, anti-PTM antibody levels correlated with brain volumes, an objective measure of nervous system involvement.

Conclusions

In our NPSLE cohort, a subset of patients with SLE have anti-PTM antibodies against MAA, AGE and CarP modified proteins. Interestingly, anti-MAA and anti-CarP were more prevalent in NPSLE, a manifestation for which no biomarkers exist.

Brain-Reactive Antibodies are Potential Biomarkers for Evaluating Therapeutic Efficacy in NPSLE Patients

PURPOSE

Neuropsychiatric systemic lupus erythematosus (NPSLE) is the main cause of disability and death in systemic lupus erythematosus (SLE). It can cause cognitive impairment and organic brain syndrome. Brain-reactive antibodies, such as anti-DNA/anti-N-methyl-D-aspartate receptor (NMDAR) antibodies (DNRAbs), anti-microtubule-associated protein 2 (anti-MAP2) antibodies, and anti-glial fibrillary acidic protein (anti-GFAP) antibodies are thought to participate in the progression of NPSLE and thus considered potential diagnostic biomarkers, but whether they can be used for evaluating therapeutic efficacy in NPSLE is unknown.

PATIENTS AND METHODS

Overall, 17 NPSLE patients and 10 non-SLE controls were included in this study. All the patients were treated with glucocorticoid (GC) pulse therapy. Serum and cerebrospinal fluid (CSF) concentrations of DNRAbs and anti-MAP2 and anti-GFAP antibodies were measured using enzyme-linked immunosorbent assay. The differences between the CSF concentrations of these antibodies in NPSLE patients before and after GC pulse therapy were analyzed.

RESULTS

CSF concentrations of DNRAbs and anti-MAP2 and anti-GFAP antibodies were significantly higher in NPSLE patients compared to the non-SLE controls. Among the patients, CSF concentration of DNRAbs was significantly higher in the patients with acute confusional state (ACS) than in those with non-ACS diffuse NPSLE or focal NPSLE. Additionally, CSF concentration of DNRAbs was significantly correlated with QIgG (r=0.4884, P=0.0467) and IgG index (r=0.5319, P=0.0280) in NPSLE patients. Moreover, CSF concentrations of DNRAbs, anti-MAP2, and anti-GFAP antibodies and QIgG were significantly decreased after GC pulse therapy in NPSLE patients.

CONCLUSION

These results indicate that CSF DNRAbs and anti-MAP2 and anti-GFAP antibodies are potential biomarkers for evaluating therapeutic efficacy in NPSLE.

The effects of disease activity, inflammation, depression and cognitive fatigue on resting state fMRI in systemic lupus erythematosus

OBJECTIVES

Cognitive dysfunction (CD) and depression are interlinked comorbidities of SLE. They may be the result of altered brain mechanisms. This study aimed to examine SLE effects on functional connectivity (FC) within the default mode network (DMN) using resting state fMRI-and how depression may impact this.

METHODS

Demographic, clinical and psychiatric data were collected from 19 SLE-active, 23 SLE-stable and 30 healthy controls (HC) participants. A T2*-weighted rsfMR scan was acquired and analysed using independent component analysis (ICA). Group z-scores for nodes associated with the DMN were tested. Significant nodes were entered into a factor analysis. The combined factor was used in correlations with factors of interest. Significant variables were used in a mediation analysis.

RESULTS

14 DMN nodes were defined using ICA. In five nodes, the SLE groups had significantly reduced FC compared with the HC group (p < 0.01). Factor analysis generated one factor that only depression score correlated with for both the HC group (rs=-0.510) and SLE groups combined (rs=-0.390). Mediation analysis revealed depression score accounted for 22% of the altered FC in the DMN. Disease state accounted for the remaining 78%.

CONCLUSIONS

Altered FC was evident in DMN nodes for SLE groups irrespective of disease activity. Depression accounts for some of this effect but SLE directly accounted for more. Further studies are needed to assess if these changes may be a precursor to CD in SLE. If so, rs-fMRI could be an early marker for CD in SLE and help in future CD in SLE treatment trials.

Association between IL-37 and Systemic Lupus Erythematosus Risk

Interleukin-37 (IL-37) is an anti-inflammatory cytokine. In our former study, we found increased plasma IL-37 levels in systemic lupus erythematosus (SLE) patients. However, relationship between IL-37 levels and clinical laboratory characteristics of SLE patients has not been elucidated. In addition, association of IL37 gene polymorphism with SLE risk needs to be discussed. A group of 580 individuals (220 SLE patients and 360 healthy controls) in a Southern Chinese Han population were recruited. Plasma IL-37 levels were evaluated using enzyme-linked immunosorbent assay (ELISA). Four single-nucleotide polymorphisms (rs3811047, rs2723186, rs2723176 and rs4364030) of IL37 gene were genotyped. Relationship of IL-37 expression, IL37 gene polymorphisms and clinical characteristics was discussed. We found that plasma levels of IL-37 were negatively associated with SLE disease activity index (SLEDAI) (r_s = -0.352, P = .001), and were higher in less active patients compared with active patients (P = .003). Decreased levels of IL-37 were found in SLE patients with discoid rash when compared to patients who did not have this symptom (P < .001). Plasma IL-37 levels were significantly lower in patients with hypocomplementemia comparing to those without this feature (P = .009). Levels of IL-37 in SLE with positive proteinuria were lower than patients with negative proteinuria (P = .046). Furthermore, allele distribution of rs2723186, rs4364030 between SLE cases and healthy individuals was significantly different (P = .001, P = .010, respectively). Genotype of rs4364030 was different between SLE cases and controls (P = .015). Haplotype analysis revealed that the frequency of haplotype CG (rs2723176 (C) +rs2723186 (G)) was higher in SLE, as compared with healthy individuals (P = .002). In conclusion, the plasma levels of IL-37 were related to SLE severity, and IL37 gene polymorphisms (rs2723186, rs2723176 and rs4364030) may associate with SLE susceptibility.