Combining multimodal magnetic resonance brain imaging and machine learning to unravel neurocognitive function in non-neuropsychiatric systemic lupus erythematosus.

OBJECTIVE: To study whether multimodal brain MRI comprising permeability and perfusion measures coupled with machine learning can predict neurocognitive function in young patients with SLE without neuropsychiatric manifestations. METHODS: SLE patients and healthy controls (HCs) (≤40 years of age) underwent multimodal structural brain MRI that comprised voxel-based morphometry (VBM), magnetization transfer ratio (MTR) and dynamic contrast-enhanced (DCE) MRI in this cross-sectional study. Neurocognitive function assessed by Automated Neuropsychological Assessment Metrics was reported as the total throughput score (TTS). Olfactory function was assessed. A machine learning-based model (i.e. glmnet) was constructed to predict TTS. RESULTS: Thirty SLE patients and 10 HCs were studied. Both groups had comparable VBM, MTR, olfactory bulb volume (OBV), olfactory function and TTS. While after correction for multiple comparisons the uncorrected increase in the blood-brain barrier (BBB) permeability parameters compared with HCs did not remain evident in SLE patients, DCE-MRI perfusion parameters, notably an increase in right amygdala perfusion, was positively correlated with TTS in SLE patients (r = 0.636, false discovery rate P < 0.05). A machine learning-trained multimodal MRI model comprising alterations of VBM, MTR, OBV and DCE-MRI parameters mainly in the limbic system regions predicted TTS in SLE patients (r = 0.644, P < 0.0005). CONCLUSION: Multimodal brain MRI demonstrated increased right amygdala perfusion that was associated with better neurocognitive performance in young SLE patients without statistically significant BBB leakage and microstructural abnormalities. A machine learning-constructed multimodal model comprising microstructural, perfusion and permeability parameters accurately predicted neurocognitive performance in SLE patients.

Platelet TLR7 is essential for the formation of platelet-neutrophil complexes and low-density neutrophils in lupus nephritis.

OBJECTIVES: Platelets and low-density neutrophils (LDNs) are major players in the immunopathogenesis of SLE. Despite evidence showing the importance of platelet-neutrophil complexes (PNCs) in inflammation, little is known about the relationship between LDNs and platelets in SLE. We sought to characterize the role of LDNs and Toll-like receptor 7 (TLR7) in clinical disease. METHODS: Flow cytometry was used to immunophenotype LDNs from SLE patients and controls. The association of LDNs with organ damage was investigated in a cohort of 290 SLE patients. TLR7 mRNA expression was assessed in LDNs and high-density neutrophils (HDNs) using publicly available mRNA sequencing datasets and our own cohort using RT-PCR. The role of TLR7 in platelet binding was evaluated in platelet-HDN mixing studies using TLR7-deficient mice and Klinefelter syndrome patients. RESULTS: SLE patients with active disease have more LDNs, which are heterogeneous and more immature in patients with evidence of kidney dysfunction. LDNs are platelet bound, in contrast to HDNs. LDNs settle in the peripheral blood mononuclear cell (PBMC) layer due to the increased buoyancy and neutrophil degranulation from platelet binding. Mixing studies demonstrated that this PNC formation was dependent on platelet-TLR7 and that the association results in increased NETosis. The neutrophil:platelet ratio is a useful clinical correlate for LDNs, and a higher NPR is associated with past and current flares of LN. CONCLUSIONS: LDNs sediment in the upper PBMC fraction due to PNC formation, which is dependent on the expression of TLR7 in platelets. Collectively, our results reveal a novel TLR7-dependent crosstalk between platelets and neutrophils that may be an important therapeutic opportunity for LN.

Post-mRNA vaccine flares in autoimmune inflammatory rheumatic diseases: Results from the COronavirus National Vaccine registry for ImmuNe diseases SINGapore (CONVIN-SING).

BACKGROUND: Studies of flares of autoimmune inflammatory rheumatic diseases (AIIRD) after COVID-19 mRNA vaccination are limited by small sample size, short follow up or at risk of selection bias. METHODS: A national retrospective cohort study of consecutive AIIRD patients ≥12 years old, across 8 hospitals who received at least one dose of a COVID-19 mRNA vaccine. Patients were included from the date of 1st vaccine dose and censored at the time of flare or on the date of the clinic visit at least 3 months from cohort entry, whichever came first. Predictors of flare were determined by Cox proportional hazards analysis. FINDINGS: 4627 patients (73% Chinese, 71% female) of median (IQR) age 61 (48, 70) years were included; 42% Rheumatoid arthritis, 14% Systemic lupus erythematosus and 11% Psoriatic arthritis. 47% were in remission, 41% low disease activity, 10% moderate disease activity and 1% in high disease activity. 18% patients flared, of which 11.7% were within the 3-month period of interest. 11.8% patients improved. Median (IQR) time-to-flare was 60 (30, 114) days. 25% flares were self-limiting, 61% mild-moderate and 14% severe. Older patients (53-65 years and >66 years) had a lower risk of flare [HR 0.6 (95% CI 0.5-0.8) and 0.7 (0.6-0.8) respectively]. Patients with inflammatory arthritis and with active disease had a higher risk of flare [HR 1.5 (1.2-2.0) and 1.4 (1.2-1.6), respectively]. Treatment with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs), immunosuppression and prednisolone was also associated with an increased risk of flare [HR 1.5 (1.1-2), 1.2 (1.1-1.4) and 1.5 (1.2-1.8) for prednisolone ≤7.5 mg respectively]. INTERPRETATION: There was a moderately high rate of AIIRD flares after mRNA vaccination but also improvement in several patients. Severe flares and hospitalisation were rare. Thus, vaccination remains safe and highly recommended.

Distinct transcriptomic and metabolomic profiles characterize NSAID-induced urticaria/angioedema patients undergoing aspirin desensitization.

BACKGROUND: There is limited data on the mechanisms of aspirin desensitization in patients with nonsteroidal anti-inflammatory drug (NSAID)-induced urticaria/angioedema (NIUA). OBJECTIVES: We sought to characterize the transcriptomic and metabolomic profiles of patients with NIUA undergoing aspirin desensitization. METHODS: PBMCs and plasma were separated from the blood of patients with NIUA undergoing aspirin desensitization for coronary artery disease and NSAID-tolerant controls. RNA was isolated from PBMCs and subjected to messenger RNA (mRNA)- and long noncoding RNA (lncRNA)-sequencing. Plasma samples were analyzed using LC-MS/MS for metabolite shifts using a semitargeted metabolomics panel. RESULTS: Eleven patients with NIUA and 10 healthy controls were recruited. The mRNA gene profiles of predesensitization versus postdesensitization and healthy control versus postdesensitization did not differ significantly. However, we identified 739 mRNAs and 888 lncRNAs as differentially expressed from preaspirin desensitization patients and controls. A 12-mRNA gene signature was trained using a machine learning algorithm to distinguish between controls, postdose, and predose samples. Ingenuity Pathway Analysis identified 5 canonical pathways that were significantly enriched in preaspirin desensitization samples. IL-22 was the most upregulated pathway. To investigate the potential regulatory roles of the differentially expressed lncRNA on the mRNAs, 9 lncRNAs and 12 mRNAs showed significantly correlated expression patterns in the IL-22 pathway. To validate the transcriptomics data, IL-22 was measured in the plasma samples of the subjects using ELISA. IL-22 was significantly higher in preaspirin desensitization patients compared with controls. In parallel, metabolomic analysis revealed stark differences in plasma profiles of preaspirin desensitization patients and healthy controls. In particular, 2-hydroxybenzoic acid (salicylic acid) was significantly lower in preaspirin desensitization patients compared with healthy controls. CONCLUSIONS: This is the first study to combine both transcriptomic and metabolomic approaches in patients with NIUA, which contributes to a deeper understanding about the pathogenesis of NIUA and may potentially pave the way toward a molecular diagnosis of NSAID hypersensitivity.

Risk factors for immune-related adverse events from anti-PD-1 or anti-PD-L1 treatment in an Asian cohort of nonsmall cell lung cancer patients.

Immune-related adverse events (IrAEs) of immune checkpoint inhibitors (ICIs) can be serious and unpredictable. We examine the incidence rate and risk factors for IrAEs in an Asian cohort of nonsmall cell lung cancer (NSCLC) patients treated with immunotherapy. Between June 2014 and August 2020, we retrospectively analysed IrAEs in NSCLC patients treated with anti-PD-1 or anti-PD-L1 inhibitors at the National University Cancer Institute, Singapore. A Poisson regression model was used to estimate the effect of risk factors on incidence rate of any grade IrAEs. One hundred and forty-one patients were enrolled. Median age was 63. Majority were male (67%) with Eastern Cooperative Oncology Group (ECOG) PS 0-1 (77%). More than half (56%) received pembrolizumab. Eleven percent harboured epidermal growth factor receptor (EGFR) mutation. Eighteen percent received concomitant chemotherapy. Median number of cycles was 4, and median duration of treatment was 2.1 months. IrAEs were seen in 71 (50.4%) patients, with an incidence rate of 99 events per 1000 person-months. Fatigue (25%), rash (10.5%) and pneumonitis (7.9%) were the most common IrAEs. Twenty out of 152 IrAEs (13.2%) were Grade 3 or higher in severity: most common being pneumonitis (5.3%), fatigue (3.3%) and transaminitis (1.3%). Multivariable analysis demonstrated that concomitant chemotherapy use, higher BMI and presence of EGFR mutation are significant predictors for IrAEs (P < .0001; P = .016; P = .007). Our findings can help guide risk stratification and monitoring of IrAEs among NSCLC patients on immunotherapy.

Impact of teleconsultation on subsequent disease activity and flares in patients with systemic lupus erythematosus.

OBJECTIVES: Despite the widespread adoption of teleconsultations amid the COVID-19 pandemic, their safety in SLE patients has not been evaluated. Here, we examined subsequent disease activity and flares among SLE patients who received teleconsultation vs in-person consultation. To discern differences in physicians' prescription behaviour during both forms of consultations, we compared corticosteroid dose adjustments. METHODS: We studied adult SLE patients who were seen between 1 February 2020 and 1 February 2021. At each patient-visit, rheumatologists utilized phone/video teleconsultation or physical consultation at their discretion. Disease activity was assessed with SLE Disease Activity Index 2000 (SLEDAI-2K) and flares were defined by the SELENA-SLEDAI Flare Index (SFI). We derived a propensity score for patients who were chosen for physical consultation. Multivariable generalized estimation equations were used to analyse SLEDAI-2k and flare at the next visit, adjusted for the propensity score. RESULTS: A total of 435 visits were recorded, of which 343 (78.9%) were physical visits and 92 (21.1%) were teleconsultations. The modality of consultation did not predict flare [OR for physical consultation (95% CI) 0.42 (0.04, 5.04), P =0.49] or SLEDAI-2k at the next visit [estimate of coefficient for physical consultation (95% CI) -0.19 (-0.80, 0.43), P =0.55]. Adjustments of prednisolone dosages were comparable between the two forms of visits [OR for physical consultation (95% CI) 1.34 (0.77, 2.34), P =0.30]. CONCLUSION: SLE disease activity and flares at the subsequent visit were similar between teleconsultations and physical consultations. Medication prescription behaviour, determined using adjustment in corticosteroid dosages, was not different between the two forms of visits.

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 are well documented in patients with SLE. Yet, the 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 (HCs) [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 HCs. Association between extracellular FW changes and neurocognitive performance was studied. RESULTS: SLE patients had higher WM extracellular FW compared with HCs (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, intelligence quotient, and total WM volume. CONCLUSION: 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.

Type I Interferons in Systemic Lupus Erythematosus: A Journey from Bench to Bedside.

Dysregulation of type I interferons (IFNs) has been implicated in the pathogenesis of systemic lupus erythematosus (SLE) since the late 1970s. The majority of SLE patients demonstrate evidence of type I IFN pathway activation; however, studies attempting to address the relationship between type I IFN signature and SLE disease activity have yielded conflicting results. In addition to type I IFNs, type II and III IFNs may overlap and also contribute to the IFN signature. Different genetic backgrounds lead to overproduction of type I IFNs in SLE and contribute to the breakdown of peripheral tolerance by activation of antigen-presenting myeloid dendritic cells, thus triggering the expansion and differentiation of autoreactive lymphocytes. The consequence of the continuous stimulation of the immune system is manifested in different organ systems typical of SLE (e.g., mucocutaneous and cardiovascular involvement). After the discovery of the type I IFN signature, a number of different strategies have been developed to downregulate the IFN system in SLE patients, finally leading to the successful trial of anifrolumab, the second biologic to be approved for the treatment of SLE in 10 years. In this review, we will discuss the bench to bedside translation of the type I IFN pathway and put forward some issues that remain unresolved when selecting SLE patients for treatment with biologics targeting type I IFNs.

Takotsubo syndrome and rheumatic diseases-a critical systematic review.

Since its description in 1990, Takotsubo syndrome (TTS), an acute cardiac condition triggered by physical or emotional stress, has been believed to be related to catecholamine surge from overwhelming sympathetic activity. While symptomatology, biochemical features, ECG and echocardiogram alterations are largely indistinguishable from acute coronary syndrome, the absence of culprit coronary lesions often necessitates further investigations, uncovering underlying inflammatory processes. Mechanistically, animal models of TTS reveal early neutrophil infiltration followed by staged ingression of two subtypes of macrophages (M1, M2) mediating initial acute inflammatory changes (M1), followed by switching to anti-inflammatory signals (M2) that enhance myocardial tissue recovery. Here, we begin with a description of two TTS patients with primary Sjögren's syndrome and Takayasu's arteritis, followed by a systematic literature review that summarizes the demographic and clinical features of TTS patients with rheumatological conditions. Potential impact of disease manifestations and treatment of rheumatological conditions on TTS are critically discussed.

The allergic myocardial infarction dilemma: is it the anaphylaxis or the epinephrine?

We highlight two distinct cases of myocardial infarction occurring concurrently with anaphylaxis at our centre in Singapore. The first case had cardiac symptoms and electrocardiogram changes concomitant with his anaphylaxis presentation, suggestive of Kounis syndrome, while the second case presented with anaphylaxis and only developed cardiac symptoms and electrocardiogram changes after treatment with intramuscular epinephrine, suggestive of epinephrine-induced myocardial infarction. Both these conditions are uncommon and under-recognised, and we review the current literature to compare the similarities and differences in their clinical manifestations, pathophysiology, and management. Kounis syndrome occurs secondary to mast cell degranulation ultimately resulting in coronary vasospasm, platelet activation and inflammatory response, whereas epinephrine causes platelet aggregation. Therefore, treatment priorities of Kounis syndrome are treatment of allergy, treatment of vasospasm, and treatment with anti-platelet therapy and revascularization if coronary plaques are present. For epinephrine-induced myocardial infarction, after epinephrine treatment is discontinued, considerations in management are re-vascularisation or pharmacotherapy. Further research will help with better understanding of both conditions and formulation of clinical management guidelines.

Mathematical processing is affected by daily but not cumulative glucocorticoid dose in patients with systemic lupus erythematosus.

OBJECTIVES: The impact of glucocorticoids on neurocognitive performance in patients with SLE is not fully addressed. We aimed to study the effect of daily and cumulative glucocorticoid dose on neurocognitive performance in SLE patients. METHODS: Consecutive SLE patients and gender- and age-matched healthy controls (HCs) underwent the computer-based Automated Neuropsychological Assessment Matric (ANAM), which evaluates eight neurocognitive domains including learning, recall, visual perception, mental rotation, short-term memory, attention, sustained attention and working memory. The total and individual-domain throughput scores (TPSs) and the presence of cognitive dysfunction (total TPS <1.5 s.d. below the mean TPS of HCs) were compared between SLE patients and HCs. Within the SLE group, univariate and independent associations between prednisolone dose (daily and cumulative) and individual-domain TPS were studied by univariate and multivariable linear regression, respectively. RESULTS: A total of 96 SLE patients and 96 HCs were studied. SLE patients scored significantly worse across all the neurocognitive domains and had a significantly lower mean total TPS (P < 0.001) and a higher prevalence of cognitive dysfunction compared with HCs (25.0 vs 7.3%, P = 0.001). In SLE patients, daily prednisolone dose was significantly and negatively correlated with mathematical-processing TPS, which probes working memory (P = 0.018). No significant correlation between cumulative prednisolone dose and any of the individual-domain TPSs was found. In multivariable regression, higher daily prednisolone dose and doses >9 mg daily remained independently associated with lower mathematical-processing TPSs (P = 0.031). CONCLUSION: Daily prednisolone dose ≥9 mg, but not cumulative glucocorticoid dose, had an independent negative impact on mathematical processing in SLE patients.

Biologics targeting type I interferons in SLE: A meta-analysis and systematic review of randomised controlled trials.

OBJECTIVE: The feed-forward loop of type I interferons (IFNs) production and subsequent immunopathology of systemic lupus erythematosus (SLE) has been hypothesised to be disrupted with inhibition of IFNα or type I IFN receptor subunit 1 (IFNAR). This systematic review and meta-analysis present the treatment efficacy and safety profile of monoclonal antibodies inhibiting IFNα or IFNAR. METHODS: A search was done using Medline, Embase and ClinicalTrials.gov for biologics targeting IFNα or IFNAR in SLE up to 3 Jan 2020. For the meta-analysis, analyses of binary variables were pooled using odds ratio (OR) with the Mantel Haenszel model. RESULTS: Anifrolumab 300 mg (n = 3 studies, 927 patients) was more effective than placebo in achieving SRI(4) (pooled OR = 1.91, CI 1.11-3.28, P = 0.02) and BICLA response (pooled OR = 2.25, CI 1.72-2.95, P < 0.00001). In SLE patients with high type I IFN gene signature, SRI(4) response was not achieved with anifrolumab in 2 studies, 450 patients. Treatment with IFNα and IFNAR inhibitors (n = 7 studies, 1590 patients) increased the risk of herpes zoster infection (pooled OR = 3.72, CI 1.88-7.39, P = 0.0002), upper respiratory tract infections, nasopharyngitis and bronchitis. CONCLUSION: This meta-analysis substantiates IFNAR as a therapeutic target in SLE. Inhibition of type I IFNs predisposes to herpes zoster and other viral infections.

A Flow Cytometry-Based Assay for High-Throughput Detection and Quantification of Neutrophil Extracellular Traps in Mixed Cell Populations.

Neutrophil extracellular traps (NETs) are web-like structures composed of decondensed chromatin and antimicrobial proteins that are released into the extracellular space during microbial infections. This active cell death program is known as NETosis. To date, florescence microscopy is the widely accepted method for visualization and quantification of NETs. However, this method is subjective, time consuming and yields low numbers of analyzed polymorphonuclear cells (PMNs) per sample. Increasing interest has emerged on the identification of NETs using flow cytometry techniques. However, flow cytometry analysis of NETs requires particular precautions for sample preparation to obtain reproducible data. Herein, we describe a flow cytometry-based assay for high-throughput detection and quantification of NETosis in mixed cell populations. We used fluorescent-labeled antibodies against cell markers on PMNs together with a combination of nucleic acid stains to measure NETosis in whole blood (WB) and purified PMNs. Using plasma membrane-impermeable DNA-binding dye, SYTOX Orange (SO), we found that cell-appendant DNA of NETting PMNs were positive for SO and DAPI. The combination of optimally diluted antibody and nucleic acid dyes required no washing and yielded low background fluorescence. Significant correlations were found for NETosis from WB and purified PMNs. We then validated the assay by comparing with time-lapse live cell fluorescence microscopy and determined very good intraassay and interassay variances. The assay was then applied to a disease associated with NETosis, systemic lupus erythematosus (SLE). We examined PMA-induced NETosis in peripheral PMNs from SLE patients and controls and in bone marrow PMNs from multiple murine models. In summary, this assay is observer-independent and allows for rapid assessment of a large number of PMNs per sample. Use of this assay does not require sophisticated microscopic equipment like imaging flow cytometers and may be a starting point to analyze extracellular trap formation from immune cells other than PMNs. © 2018 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

Diagnosing and attributing neuropsychiatric events to systemic lupus erythematosus: time to untie the Gordian knot?

Neurological and psychiatric syndromes, collectively referred to as NPSLE, occur frequently in SLE. The frequency of NPSLE varies from 21 to 95%; however, only 13-38% of neuropsychiatric (NP) events could be attributable to SLE in the NPSLE SLICC inception cohort. This variability in the frequency of NPSLE is attributable to the low specificity of the ACR case definitions for SLE-attributed NP syndromes, inclusion of minor NP events in the ACR nomenclature, difficulty in ascertainment of NP events and diverse experience of rheumatologists in the clinical assessment of NP events. Making the correct and early attribution of NP events to SLE is important to institute appropriate immunosuppressive treatment for favourable outcomes. Various attribution models using composite decision rules have been developed and used to ascribe NP events to SLE. This review will focus on the various clinical presentations, diagnostic work-up and attributions of the common NPSLE syndromes, including other NP events not included in the ACR nomenclature but which have come to attention in recent years.

Bimodal Influence of Vitamin D in Host Response to Systemic Candida Infection-Vitamin D Dose Matters.

Vitamin D level is linked to susceptibility to infections, but its relevance in candidemia is unknown. We aimed to investigate the in vivo sequelae of vitamin D3 supplementation in systemic Candida infection. Implicating the role of vitamin D in Candida infections, we showed that candidemic patients had significantly lower 25-OHD concentrations. Candida-infected mice treated with low-dose 1,25(OH)2D3 had reduced fungal burden and better survival relative to untreated mice. Conversely, higher 1,25(OH)2D3 doses led to poor outcomes. Mechanistically, low-dose 1,25(OH)2D3 induced proinflammatory immune responses. This was mediated through suppression of SOCS3 and induction of vitamin D receptor binding with the vitamin D-response elements in the promoter of the gene encoding interferon γ. These beneficial effects were negated with higher vitamin D3 doses. While the antiinflammatory effects of vitamin D3 are well described, we found that, conversely, lower doses conferred proinflammatory benefits in Candida infection. Our study highlights caution against extreme deviations of vitamin D levels during infections.

Chlorhexidine Anaphylaxis Masquerading as Septic Shock.

Chlorhexidine is a commonly used antiseptic and disinfectant in the health-care setting. Its usage has increased in recent years with intensive campaigns and infection control guidelines to combat hospital-acquired infections. As a result, patients and health-care workers (HCW) are exposed to increasing chlorhexidine usage. In recent years, adverse reactions to chlorhexidine ranging from allergic contact dermatitis, photosensitivity, fixed drug eruptions, urticaria and anaphylactic shock have been reported. Most have been isolated case reports on adverse reactions occurring in healthy individuals or HCW. We report a case of anaphylactic shock caused by applying chlorhexidine cleansing solution and masquerading as septic shock from left-leg necrotising fasciitis.

Anti-NR2A/B Antibodies and Other Major Molecular Mechanisms in the Pathogenesis of Cognitive Dysfunction in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease that affects approximately 1-45.3 per 100,000 people worldwide. Although deaths as a result of active and renal diseases have been substantially declining amongst SLE patients, disease involving the central nervous system (CNS), collectively termed neuropsychiatric systemic lupus erythematosus (NPSLE), remains one of the important causes of death in these patients. Cognitive dysfunction is one of the most common manifestations of NPSLE, which comprises deficits in information-processing speed, attention and executive function, in conjunction with preservation of speech. Albeit a prevalent manifestation of NPSLE, the pathogenetic mechanisms of cognitive dysfunction remain unclear. Recent advances in genetic studies, molecular techniques, neuropathology, neuroimaging and cognitive science have gleaned valuable insights into the pathophysiology of lupus-related cognitive dysfunction. In recent years, a role for autoantibodies, molecular and cellular mechanisms in cognitive dysfunction, has been emerging, challenging our previous concept of the brain as an immune privileged site. This review will focus on the potential pathogenic factors involved in NPSLE, including anti-N-methyl-d-aspartate receptor subunit NR2A/B (anti-NR2A/B) antibodies, matrix metalloproteinase-9, neutrophil extracellular traps and pro-inflammatory mediators. Better understanding of these mechanistic processes will enhance identification of new therapeutic modalities to halt the progression of cognitive decline in SLE patients.

Environmental factors, toxicants and systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an immune-complex-mediated multi-systemic autoimmune condition of multifactorial etiology, which mainly affects young women. It is currently believed that the onset of SLE and lupus flares are triggered by various environmental factors in genetically susceptible individuals. Various environmental agents and toxicants, such as cigarette smoke, alcohol, occupationally- and non-occupationally-related chemicals, ultraviolet light, infections, sex hormones and certain medications and vaccines, have been implicated to induce SLE onset or flares in a number case series, case-control and population-based cohort studies and very few randomized controlled trials. Here, we will describe some of these recognized environmental lupus triggering and perpetuating factors and explain how these factors potentially bias the immune system towards autoimmunity through their interactions with genetic and epigenetic alterations. Further in-depth exploration of how potentially important environmental factors mechanistically interact with the immune system and the genome, which trigger the onset of SLE and lupus flares, will certainly be one of the plausible steps to prevent the onset and to decelerate the progress of the disease.