Raised serum S100B protein levels in neuropsychiatric lupus

Biomarkers for systemic lupus erythematosus - a focus on organ damage

INTRODUCTION

Systemic lupus erythematosus (SLE) is complex autoimmune disease with heterogenous manifestations, unpredictable disease course and response to treatment. One of the critical needs in SLE management is the identification of reliable biomarkers that can aid in early diagnosis, accurate monitoring of disease activity, and assessment of treatment response.

AREAS COVERED

In the current review, we focus on the commonly affected organs (skin, kidney, and nervous system) in SLE to summarize the emerging biomarkers that show promise in disease diagnosis, monitoring and treatment response assessment. The subtitles within each organ domain were determined based on the most relevant and promising biomarkers for that specific organ damage.

EXPERT OPINION

Biomarkers have the potential to significantly benefit the management of SLE by aiding in diagnosis, disease activity monitoring, prognosis, and treatment response assessment. However, despite decades of research, none has been validated and implemented for routine clinical use. Novel biomarkers could lead to the development of precision medicine for SLE, guide personalized treatment, and improve patient outcomes. Challenges in biomarker research in SLE include defining clear and clinically relevant questions, accounting for the heterogeneity of SLE, and confirming initial findings in larger, multi-center, multi-ethnic, independent cohorts that reflect real-world clinical scenarios.

Neuropsychiatric Manifestations in Systemic Lupus Erythematosus Patients at a Tertiary Hospital in Peru

BACKGROUND

Systemic lupus erythematosus is a prevalent autoimmune disease that affects multiples systems, exerting its most incapacitating and life-threatening impact through neuropsychiatric involvement. According to the American College of Rheumatology (ACR), 19 neuropsychiatric syndromes types of SLE are classified into categories encompassing the central and peripheral nervous systems. This study aimed to investigate the frequency of neuropsychiatric manifestations in systemic lupus erythematosus patients admitted to Hospital Cayetano Heredia in Lima, Peru, between 2008 and 2019.

METHODS

A retrospective observational study was conducted, entailing the review of 240 medical records of patients diagnosed with systemic lupus erythematosus during the specified period, based on the Systemic Lupus International Collaborating Clinics (SLICC) 2012 criteria. Among these records, 55 patients presented neuropsychiatric systemic lupus erythematosus (NPSLE). Data were collected using standardized form and entered into Microsoft Excel 2019 database. Statistical analysis was performed using Stata v16.

RESULTS

The frequency of neuropsychiatric compromise in systemic lupus erythematosus patients was found to be 22.91%. Among the 55 systemic lupus erythematosus patients, 40 demonstrated involvement of the central nervous system (72.72%), 2 exhibited involvement of the peripheral nervous system (3.63%), and 13 displayed involvement in both the central nervous system and peripheral nervous system (23.63%). The most prevalent psychiatric disorder observed was a major depressive disorder, with a prevalence rate of 30.9%.

CONCLUSION

The study revealed a frequency of 22.91% for neuropsychiatric involvement in systemic lupus erythematosuspatients at Cayetano Heredia Hospital between 2008 and 2019, with central nervous system manifestations prevailing. Furthermore, the findings suggest that NPSLE commonly manifested after the diagnosis of systemic lupus erythematosus.

Emerging Molecular Markers Towards Potential Diagnostic Panels for Lupus

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease which can affect various tissues and organs, posing significant challenges for clinical diagnosis and treatment. The etiology of SLE is highly complex with contributions from environmental factors, stochastic factors as well as genetic susceptibility. The current criteria for diagnosing SLE is based primarily on a combination of clinical presentations and traditional lab testing. However, these tests have suboptimal sensitivity and specificity. They are unable to indicate disease cause or guide physicians in decision-making for treatment. Therefore, there is an urgent need to develop a more accurate and robust tool for effective clinical management and drug development in lupus patients. It is fortunate that the emerging Omics have empowered scientists in the discovery and identification of potential novel biomarkers of SLE, especially the markers from blood, urine, cerebrospinal fluids (CSF), and other bodily fluids. However, many of these markers have not been carefully validated for clinical use. In addition, it is apparent that individual biomarkers lack sensitivity or specificity. This review summarizes the sensitivity, specificity and diagnostic value of emerging biomarkers from recent studies, and discusses the potential of these markers in the development of biomarker panel based diagnostics or disease monitoring system in SLE.

Neuro-psychiatric manifestations in patients with systemic lupus erythematosus: A systematic review and results from the Swiss lupus cohort study

Objectives

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease associated with neuro-psychiatric (NP) manifestations. Frequency and patterns of neuro-psychiatric systemic lupus erythematosus (NPSLE) vary substantially between patients. We conducted a systematic review (SR) of the literature and examined prevalence and characteristics of NPSLE in the Swiss SLE cohort study (SSCS).

Methods

The SR search was performed between January 1999 and January 2020. We included prospective/cross-sectional studies focusing on NPSLE. We secured study characteristics, cohort compositions and frequencies of NP manifestations, assessed heterogeneity across reports and investigated sources of variation using meta-regression models. Regarding the SSCS, we reviewed all patients included and classified NP manifestations.

Results

The SR searches identified 530 studies. We included 22 studies in our meta-analysis, the mean frequency of NPSLE ranged from 10.6% to 96.4%. The frequency of NPSLE in the SSCS was 28.1%. Severe events including cerebrovascular insults, seizures and psychosis appeared in 7.1%, 5.3% and 6.5% respectively. There was a linear relationship between duration of SLE and cumulative incidence of NPSLE.

Conclusions

The spectrum of NPSLE is very broad. The diagnostic work-up and rates of reported manifestations varied substantially across studies. We call for concerted efforts and consensus regarding definitions of NPSLE that will facilitate accurate diagnosis and attribution to SLE, particularly with a view to timely intervention and patient outcomes.

Posterior reversible encephalopathy syndrome: A neuropsychiatric manifestation of systemic lupus erythematosus

Posterior Reversible Encephalopathy Syndrome (PRES) is an acute neurological syndrome clinically characterized by seizures, altered mental status, headache, and visual disturbances. It is caused by a variety of abnormalities in the endothelial function that ultimately result in vasogenic edema in the circulation of the central nervous system. This is reflected by the neuroimaging findings, that most often show reversible parieto-occipital edema. An important proportion of patients with PRES present with Systemic Lupus Erythematosus (SLE), and its complications, as their sole risk factors. This review describes the relationship between these two clinical entities and explains the pathophysiological models that have been proposed to describe the development of PRES. We explain how SLE can cause alterations in every pathway implicated in the development of PRES. Given the relatively high frequency and the distinct clinical course, PRES in the setting of SLE might be best described as a distinct neuropsychiatric syndrome associated with SLE.

Peripheral levels of brain-derived neurotrophic factor and S100B in neuropsychiatric systemic lupus erythematous

BACKGROUND

The aim of this study was to investigate serum S100B and brain-derived neurotrophic factor (BDNF) in systemic lupus erythematous (SLE) patients, with and without neuropsychiatric (NP) manifestation activity.

METHODS

We assessed 47 SLE patients and 20 selected healthy individuals. Disease activity was assessed according to the SLE disease activity index (SLEDAI). Serum BDNF and S100B were measured by enzyme-linked immunosorbent assay.

RESULTS

Serum S100B protein was significantly higher in SLE patients. BDNF levels were significantly decreased in active SLE, when compared with inactive SLE, but not when compared with controls. S100B was clearly higher in the NPSLE group, when compared with the non-NPSLE or control groups. Receiver operating characteristic analysis of S100B revealed an area under the curve of 0.706 that discriminated NPSLE patients with peripheral polyneuropathy.

CONCLUSIONS

Our findings reinforce the use of serum S100B as a biomarker in SLE, particularly for NPSLE. Moreover, we found a strong association between serum S100B and peripheral neuropathy, indicating a specific utility for this biomarker in SLE that warrants clinical investigation.

Blood brain barrier: A review of its anatomy and physiology in health and disease

The blood-brain barrier (BBB) is the principal regulator of transport of molecules and cells into and out of the central nervous system (CNS). It comprises endothelial cells, pericytes, immune cells, astrocytes, and basement membrane, collectively known as the neurovascular unit. The development of the barrier involves many complex pathways from all the progenitors of the neurovascular unit, but the timing of its formation is not entirely known. The coordinated activities of all the components of the neurovascular unit and other tissues ensure that materials required for growth and maintenance are allowed into the CNS while extraneous ones are excluded. This review summarizes current knowledge of the anatomy, development, and physiology of the BBB, and alterations that occur in disease conditions. Clin. Anat. 31:812-823, 2018. © 2018 Wiley Periodicals, Inc.

Prevalence, risk factors, and impact on mortality of neuropsychiatric lupus: a prospective, single-center study

Objective The objective of this paper is to identify the prevalence, risk factors, and impact on mortality of neuropsychiatric systemic lupus erythematosus (NPSLE). Methods Patients from the Hanyang BAE lupus cohort were registered and followed from 1998 to 2015. NPSLE was defined using American College of Rheumatology (ACR) case definitions and Ainiala criteria. Demographics, autoantibodies, Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), and Systemic Lupus International Collaborating Clinic (SLICC)/ACR Damage Index were collected at baseline and then annually. Mortality data were derived by linking data from the Korean National Statistics Office. Multivariable logistic regression and Cox regression analysis were conducted in the inception cohort to assess the risk factors and mortality impact of NPSLE. Results Of 1121 registered patients, 429 (38.3%) had NPSLE manifestations according to ACR criteria and 216 (19.3%) by Ainiala criteria. In multivariable logistic regression analysis, higher SLEDAI (OR 1.08, CI 1.01-1.16, p = 0.02) and antiphospholipid antibody positivity (OR 1.72, CI 1.03-2.87, p = 0.04) at SLE diagnosis increased NPSLE risk, while elevated anti-dsDNA antibodies (OR 0.43, CI 0.24-0.78, p < 0.01) and greater education duration (OR 0.92, CI 0.85-1.00, p = 0.04) showed reduced risk of NPSLE. Cox proportional hazard models demonstrated that presence of NPSLE had a three-fold increased risk of mortality (HR 3.09, CI 1.03-9.21, p = 0.04), especially in patients with focal CNS NPSLE (HR = 7.83, CI 2.12-28.96, p < 0.01). Conclusion Higher SLEDAI, antiphospholipid antibody positivity, absence of anti-dsDNA antibody at SLE diagnosis, and fewer years of education are risk factors for development of NPSLE. Presence of NPSLE, especially focal CNS NPSLE, increased the risk of mortality in SLE patients.

S100β is associated with cognitive impairment in childhood-onset systemic lupus erythematosus patients

Objective

To investigate serologic S100β protein levels in childhood-onset SLE patients (cSLE) and to elucidate their association with disease activity and neuropsychiatric (NP) manifestations.

Methods

We included 71 cSLE patients (67 females; median age 18 years; range 9–37 and 53 (47 females; median age of 20 years; range 6–29) age and sex matched healthy controls. Neurological manifestations were analysed according to the American College of Rheumatology (ACR) criteria. Cognitive evaluation was performed in all participants using Wechsler Intelligence Scale for Children (WISC-III) and Wechsler Adult Intelligence Scale (WAIS), according to age, and validated in Portuguese. SLE patients were further assessed for clinical and laboratory SLE manifestations, disease activity (SLE Disease Activity Index (SLEDAI)), damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI)) and current drug exposures. Sera S100β protein levels were measured by enzyme-linked immunosorbent assay using commercial kits.

Results

The median S100β protein level was 116.55 pg/mL (range 1.53–468.50) in cSLE and 54.98 pg/mL (range 0.69–181.00) in healthy controls ( p < 0.001). An association was observed between S100β protein and NP manifestations ( p = 0.03). The S100β protein levels was associated with cognitive impairment in cSLE patients ( p = 0.006).

Conclusions

S100β protein levels are increased in cSLE with cognitive impairment. S100β may be considered a potential biomarker that underlies central nervous system (CNS) dysfunction, especially cognitive impairment.

Lupus brain fog: a biologic perspective on cognitive impairment, depression, and fatigue in systemic lupus erythematosus

Cognitive disturbances, mood disorders and fatigue are common in SLE patients with substantial adverse effects on function and quality of life. Attribution of these clinical findings to immune-mediated disturbances associated with SLE remains difficult and has compromised research efforts in these areas. Improved understanding of the role of the immune system in neurologic processes essential for cognition including synaptic plasticity, long term potentiation and adult neurogenesis suggests multiple potential mechanisms for altered central nervous system function associated with a chronic inflammatory illness such as SLE. This review will focus on the biology of cognition and neuroinflammation in normal circumstances and potential biologic mechanisms for cognitive impairment, depression and fatigue attributable to SLE.

Anti-NR2 antibodies, blood-brain barrier, and cognitive dysfunction

Cognitive dysfunction (CD) is one of the most common neuropsychiatric manifestations of systemic lupus erythematosus (SLE). In animal models, antibodies to NR2 subunit of N-methyl D-aspartate receptor (anti-NR2) cause memory impairment, but only with blood-brain barrier (BBB) disruption or intrathecal administration. Several studies have failed to find association of aNR2 with CD, but none have assessed BBB integrity. S100B, an astrocyte-specific protein, has been used as biomarker of BBB disruption in traumatic brain injury and some neurodegenerative disorders. Antibodies to this immunologically privileged protein (anti-S100B) might indicate preceding BBB disruption. We hypothesized that aNR2 antibody is pathogenic in SLE patients only with BBB disruption. Demographic, clinical, and laboratory data was collected from patients with SLE. Total throughput score (TTS) of the Automated Neuropsychological Assessment Metrics (ANAM) was used as primary outcome measure. CD was defined as TTS < 1.5 SD below an age-, sex-, and race-matched RA population mean. Serum was analyzed by established ELISA techniques. Fifty-seven patients were evaluated and 12 had CD. Age, ethnicity, and family income were significantly different between the two groups (p < 0.05). In a multiple regression model adjusting for other variables, no significant effects of anti-NR2, S100B, or anti-S100B on TTS were found. Even at high levels of S100B and anti-S100B, no significant influence of anti-NR2 on TTS was found. The anti-NR2 was not associated with CD in SLE even in context of potential BBB disruption. This suggests that, if pathogenic, these antibodies may be produced intrathecally.

Biomarkers for CNS involvement in pediatric lupus

CNS disease, or central neuropsychiatric lupus erythematosus (cNPSLE), occurs frequently in pediatric lupus, leading to significant morbidity and poor long-term outcomes. Diagnosing cNPSLE is especially difficult in pediatrics; many current diagnostic tools are invasive and/or costly, and there are no current accepted screening mechanisms. The most complicated aspect of diagnosis is differentiating primary disease from other etiologies; research to discover new biomarkers is attempting to address this dilemma. With many mechanisms involved in the pathogenesis of cNPSLE, biomarker profiles across several modalities (molecular, psychometric and neuroimaging) will need to be used. For the care of children with lupus, the challenge will be to develop biomarkers that are accessible by noninvasive measures and reliable in a pediatric population.

Neuropsychiatric Lupus, the Blood Brain Barrier, and the TWEAK/Fn14 Pathway

Patients with systemic lupus erythematosus (SLE) can experience acute neurological events such as seizures, cerebrovascular accidents, and delirium, psychiatric conditions including depression, anxiety, and psychosis, as well as memory loss and general cognitive decline. Neuropsychiatric SLE (NPSLE) occurs in between 30 and 40% of SLE patients, can constitute the initial patient presentation, and may occur outside the greater context of an SLE flare. Current efforts to elucidate the mechanistic underpinnings of NPSLE are focused on several different and potentially complementary pathways, including thrombosis, brain autoreactive antibodies, and complement deposition. Furthermore, significant effort is dedicated to understanding the contribution of neuroinflammation induced by TNF, IL-1, IL-6, and IFN-γ. More recent studies have pointed to a possible role for the TNF family ligand TWEAK in the pathogenesis of neuropsychiatric disease in human lupus patients, and in a murine model of this disease. The blood brain barrier (BBB) consists of tight junctions between endothelial cells (ECs) and astrocytic projections which regulate paracellular and transcellular flow into the central nervous system (CNS), respectively. Given the privileged environment of the CNS, an important question is whether and how the integrity of the BBB is compromised in NPSLE, and its potential pathogenic role. Evidence of BBB violation in NPSLE includes changes in the albumin quotient (Q_alb) between plasma and cerebrospinal fluid, activation of brain ECs, and magnetic resonance imaging. This review summarizes the evidence implicating BBB damage as an important component in NPSLE development, occurring via damage to barrier integrity by environmental triggers such as infection and stress; cerebrovascular ischemia as result of a generally prothrombotic state; and immune mediated EC activation, mediated by antibodies and/or inflammatory cytokines. Additionally, new evidence supporting the role of TWEAK/Fn14 signaling in compromising the integrity of the BBB in lupus will be presented.

Association between cerebrospinal fluid S100B protein and neuronal damage in patients with central nervous system infections

PURPOSE

S100B protein is widely used as a measure of glial activity or damage in several brain conditions. Central nervous system (CNS) infections can cause neurological sequelae because of parenchyma invasion. It is difficult to predict further neuronal damage in the CNS infection. The present study is aimed to evaluate the role of the cerebrospinal fluid (CSF) S100B protein as an indicator of neuronal damage in CNS infection.

MATERIALS AND METHODS

We measured the concentration of CSF S100B protein in 62 patients with a CNS infection using an Enzyme-Linked Immunosorbent Assay. The patients with CNS infections were classified as having no neuronal damage (CNS-N) or as having neuronal damage (CNS+N) according to the presence of neurological change or structural lesions on brain MRI.

RESULTS

The CSF S100B protein level of the CNS+N group (n=22, 0.235 μg/L, 0.10-2.18) was significantly higher than that of the CNS-N group (n=40, 0.087 μg/L, 0.06-0.12) and control group (n=40, 0.109 μg/L, 0.07-0.14, p<0.01). Using an arbitrary cut off value, S100B-positive CSF was detected in 2.5% of the CNS-N group and in 50% of the CNS+N group (p<0.05).

CONCLUSION

These findings suggest that increased S100B protein levels in the CSF may be associated with the neuronal damage following CNS infections.

Psychiatric symptoms in systemic lupus erythematosus: a systematic review

OBJECTIVE

Systemic lupus erythematosus (SLE) presents with psychiatric symptoms in most patients that often remain undiagnosed and untreated. This study evaluates the prevalence of psychiatric symptoms in SLE on the basis of clinical trials that fulfilled diagnostic criteria specified by the American College of Rheumatology (ACR). Current hypotheses explaining the pathogenesis of psychiatric symptoms of lupus are reviewed to gain new insights into the neuroimmune pathogenesis of other psychiatric disorders.

DATA SOURCE

A MEDLINE search of the literature (English language only) from April 1999 to August 2011 was performed using the search terms lupus and psychiatric to identify studies of neuropsychiatric SLE.

STUDY SELECTION

Of 163 publications, 18 clinical studies were selected that focused on psychiatric symptoms, had a sample size of at least 20, and included patients of any age or gender as long as they fulfilled ACR criteria for neuropsychiatric SLE.

DATA EXTRACTION

The following data were extracted: author name, year of publication, psychiatric diagnostic method, total number of patients with SLE, and percentage of patients with individual psychiatric diagnoses. The point prevalence of psychiatric symptoms was calculated for neuropsychiatric SLE diagnoses in every study included.

RESULTS

Psychiatric symptoms are present in the majority of patients with SLE. Depression (in up to 39% of patients) and cognitive dysfunction (up to 80%) are the most common psychiatric manifestations. Genetic and environmental factors (eg, ultraviolet light, retroviruses, and medications) may play a role in the pathogenesis. In addition, the patient's reaction to the illness may result in anxiety (up to 24%) and depression. Currently known biomarkers are nonspecific for neuropsychiatric SLE and indicate inflammation, microglial activation, ischemia, oxidative stress, mitochondrial dysfunction, and blood-brain barrier dysfunction.

CONCLUSIONS

Identification of lupus-specific biomarkers of psychiatric symptoms is a high priority. Our current diagnostic assessment methods need improvement. Development of evidence-based guidelines is needed to improve diagnosis, prevention, and treatment of disabling psychiatric complications in lupus.

A lack of association between elevated serum levels of S100B protein and autoimmunity in autistic children

BACKGROUND

S100B is a calcium-binding protein that is produced primarily by astrocytes. Increased serum S100B protein levels reflect neurological damage. Autoimmunity may have a role in the pathogenesis of autism in some patients. Autoantibodies may cross the blood-brain barrier and combine with brain tissue antigens, forming immune complexes and resulting in neurological damage. We are the first to investigate the relationship between serum levels of S100B protein, a marker of neuronal damage, and antiribosomal P protein antibodies in autistic children.

METHODS

Serum S100B protein and antiribosomal P antibodies were measured in 64 autistic children in comparison to 46 matched healthy children.

RESULTS

Autistic children had significantly higher serum S100B protein levels than healthy controls (P < 0.001). Children with severe autism had significantly higher serum S100B protein than patients with mild to moderate autism (P = 0.01). Increased serum levels of antiribosomal P antibodies were found in 40.6% of autistic children. There were no significant correlations between serum levels of S100B protein and antiribosomal P antibodies (P = 0.29).

CONCLUSIONS

S100B protein levels were elevated in autistic children and significantly correlated to autistic severity. This may indicate the presence of an underlying neuropathological condition in autistic patients. Antiribosomal P antibodies may not be a possible contributing factor to the elevated serum levels of S100B protein in some autistic children. However, further research is warranted to investigate the possible link between serum S100B protein levels and other autoantibodies, which are possible indicators of autoimmunity to central nervous system in autism.

Neuropsychiatric manifestations in systemic lupus erythematosus: epidemiology, pathophysiology and management

Systemic lupus erythematosus (SLE) is a relapsing-remitting autoimmune disease with CNS involvement occurring in up to 75% of patients. However, the frequency of neuropsychiatric manifestations in SLE studies varies widely, depending on the type of manifestations included and the method used for evaluation. CNS involvement may be considered primary if directly related to SLE activity in the CNS or secondary when related to treatment, infections, metabolic abnormalities or other systemic manifestations such as uraemia and hypertension. The pathogenesis of neuropsychiatric SLE is as yet unknown, though numerous autoantibodies and cytokines have been suggested as possible mediators. However, independent of the aetiology of the insult, the final common pathway in neuropsychiatric SLE is the involvement of the cerebral microvasculature. The diagnosis of primary CNS involvement by SLE is often difficult, as both focal and diffuse manifestations may occur and there is no gold standard for diagnosis. A high index of clinical suspicion, in addition to laboratory and neuroimaging findings may support the diagnosis. Treatment is mostly empirical, although one randomized controlled trial has shown that cyclophosphamide in addition to methylprednisolone is superior to methylprednisolone alone in severe neuropsychiatric SLE.

Saliva S100B in professional sportsmen: High levels at resting conditions and increased after vigorous physical activity

BACKGROUND

Neurological dysfunction is a key medical concern in professional sportsmen (PSM). We investigated whether saliva S100B concentrations in PSM and healthy controls are modified before and after training.

METHODS

We conducted a case-control-study in 75 patients (25 PSM vs 50 controls) in which S100B saliva concentrations were expressed as absolute values and percentage of change (%) from samples drawn before (T0) and after (T1) training.

RESULTS

No differences (P>0.05) between groups were found regarding clinical, monitoring and laboratory parameters. S100B both in PSM and controls was higher at T1 when compared to T0 (P<0.01). In PSM, S100B was higher than controls (P<0.001) at T0 and T1. S100B% at T0-T1 was higher (P<0.001) in PSM and in controls and between PSM and controls (P<0.001).

CONCLUSIONS

Increased saliva S100B levels in PSM before and after training suggest a paracrine/autocrine protein's role connected to stressing activity, which becomes especially evident in PSMs.

Neuropsychiatric syndromes in systemic lupus erythematosus: a meta-analysis

OBJECTIVES

To assess the prevalence of the 19 neuropsychiatric (NP) syndromes in systemic lupus erythematosus (SLE) patients, as defined by the American College of Rheumatology (ACR) in 1999, and better understand the reasons for interstudy variability of prevalence estimates, by performing a meta-analysis of relevant publications.

METHODS

A literature search from April 1999 to May 2008 was performed to identify studies investigating NP syndromes in patients with definite SLE, applying the 1999 ACR case definitions and having a sample size of at least 30 patients. Excluded were studies that did not relate to all 19 NPSLE syndromes, presented duplicate data, or were irrelevant.

RESULTS

Seventeen of 112 identified studies matched the inclusion criteria, reporting on a total of 5057 SLE patients, including 1439 NPSLE patients, with 2709 NPSLE syndromes. In a subanalysis of the 10 higher quality prospective and elicited studies (2049 patients) using the random-effects model, the prevalence of NP syndromes in SLE patients was estimated to be 56.3% (95% CI 42.5%-74.7%), and the most frequent NP syndromes were headache 28.3% (18.2%-44.1%), mood disorders 20.7% (11.5%-37.4%), cognitive dysfunction 19.7% (10.7%-36%), seizures 9.9% (4.8%-20.5%), and cerebrovascular disease 8.0% (4.5%-14.3%), although significant between-study heterogeneity was present (P < 0.05). Autonomic disorder and Guillain-Barré syndrome carried a prevalence of less than 0.1%. No case of plexopathy was reported.

CONCLUSIONS

NP syndromes were estimated to exist in more than half of SLE patients. The most prevalent manifestations were headache, mood disorders, and cognitive dysfunction. A major limitation of the study was the significant heterogeneity of prevalence estimates between studies.

Utility of Serum S100B Protein for Identification of Central Nervous System Involvement in Systemic Lupus Erythematosus

Objective.

To evaluate utility of S100B protein in serum as a marker of central nervous system involvement in systemic lupus erythematosus (SLE).

Methods.

Forty patients with SLE, hospitalized because of central neuropsychiatric (cNP) manifestations (n = 36) and peripheral NP manifestations (pNP, n = 4) were studied. Patients were evaluated at hospitalization and 6 months later, including a serum and cerebrospinal fluid (CSF) sample. As controls, 4 SLE patients with septic meningitis (SLEsm), 13 surgical SLE patients (SLE surgical), 14 patients with nonautoimmune diseases, and 4 patients with primary NP syndromes were included. Serum and CSF S100B protein levels were determined by ELISA.

Results.

At baseline, serum levels of S100B protein did not differ across SLE groups. Using an arbitrary cutoff value, positive S100B levels in serum were observed in 7 (19%), 6 (46%), and 1 patient from the cNPSLE, SLE surgical, and SLEsm groups, respectively. S100B protein levels in cNPSLE and SLE surgical patients were similar. In CSF, S100B protein levels did not differ among SLE groups, except in patients with SLEsm. Paired serum/CSF samples were obtained in 23 patients with cNPSLE at 6 months after the acute event. Overall, levels of S100B protein in serum did not change despite the decrease observed in CSF (p = 0.004). The correlation coefficient of serum and CSF S100B protein levels among all the SLE patients at baseline was poor (r = 0.23).

Conclusion.

Serum levels of S100B protein do not differentiate SLE patients with and those without central neurological manifestations.

Risk variants in the S100B gene predict elevated S100B serum concentrations in healthy individuals

Several lines of evidence suggest an important role of the S100B protein and its coding gene in different neuropathological and psychiatric disorders like dementia, bipolar affective disorders and schizophrenia. To clarify whether a direct link exists between gene and gene product, that is, whether S100B variants directly modulate S100B serum concentration, 196 healthy individuals were assessed for S100B serum concentrations and genotyped for five potentially functional S100B SNPs. Functional variants of the serotonergic genes 5-HT1A and 5-HTT possibly modulating S100B serum levels were also studied. Further, publicly available human postmortem gene expression data were re-analyzed to elucidate the impact of S100B, 5-HT1A and 5-HTT SNPs on frontal cortex S100B mRNA expression. Several S100B SNPs, particularly rs9722, and the S100B haplotype T-G-G-A (including rs2186358-rs11542311-rs2300403-rs9722) were associated with elevated S100B serum concentrations (Bonferroni corrected P < 0.05). Of these, rs11542311 was also associated with S100B mRNA expression directly (Bonferroni corrected P = 0.05) and within haplotype G-A-T-C (rs11542311-rs2839356-rs9984765-rs881827; P = 0.004), again with the G-allele increasing S100B expression. Our results suggest an important role of S100B SNPs on S100B serum concentrations and S100B mRNA expression. It hereby links recent evidence for both, the impact of S100B gene variation on various neurological or psychiatric disorders like dementia, bipolar affective disorders and schizophrenia and the strong relation between S100B serum levels and these disorders.

Genetic contributions to the autoantibody profile in a rabbit model of Systemic Lupus Erythematosus (SLE)

For the development of rabbit models of Systemic Lupus Erythematosus (SLE), immunoglobulin allotype-defined pedigreed rabbits from the National Institute of Allergy and Infectious Diseases rabbit resource more closely approximate human populations due to their non-inbred pedigreed structure. In an initial study from this laboratory, peptides (SM and GR) from the spliceosomal Smith (Sm) and the NMDA glutamate receptor NR2b, on branched polylysine backbones (BB) elicited antinuclear and anti-dsDNA autoantibodies typical of SLE, as well as seizures and nystagmus sometimes observed as neurological manifestations in SLE patients. This suggested the feasibility of further selective breeding to develop a more reproducible rabbit model for investigations of SLE. Here we report the results of GR-MAP-8 and control BB immunization on autoantibody responses in a group of 24 rabbits specifically bred and developed from parents and ancestors tested for autoantibody responses. The changes in hematological profile and blood chemistry in the experimental rabbits were evaluated along with autoantibody responses. Elevations of total white blood cell (WBC), monocyte, eosinophil and basophil counts that developed following immunizations were moderately influenced by litter and presence of the antibody heavy chain allotype VH1a1. Autoantibody development followed a sequential pattern with anti-nuclear antibodies (ANA) followed by anti-dsDNA and subsequently anti-Sm and anti-RNP similar to SLE patients. High autoantibody levels to one autoantigen were not always associated with antibody response to another. Female rabbits had higher prevalence and levels of autoantibodies similar to human SLE. Higher autoantibody levels of anti-dsDNA and -ANA were observed among some full sibs and the presence of high responder ancestors in the pedigree was associated the augmented responses. We observed significant association between highest antibody responses to GR-MAP-8 and highest anti-dsDNA levels. Naturally occurring autoantibodies were found in some pre-immune sera and some unique ANA fluorescent staining patterns within the experimental group were observed. Background immunofluorescence in pre-immune sera, distinct patterns of programmed autoantibody responses unique among individual rabbits may have been modulated by genetic constitution, gender and environmental factors including exposure to antigens. The high incidence and intensity of autoantibody responses among descendants of high responders suggest that there may be an additive mode of inheritance with high heritability. It is conceivable that further rigorous pedigree selection for autoantibody responses could lead to development of rabbit models with spontaneous occurrence of SLE like serology and disease phenotypes.

S100 protein family and its application in clinical practice

The members of the S100 protein family are multifunctional proteins with a regulatory role in a variety of cellular processes. They exert their actions usually through calcium binding, although Zn2+ and Cu2+ have also been shown to regulate their biological activity. The most studied member, protein S100B, exhibits neurotrophic (at physiologic concentration) or neurotoxic (at higher concentration) activity and its immunohistochemical expression or serum levels have been determined in various clinical disorders. S100B has been well documented as a marker of astrocytic activation mediating its effects via interaction with receptor for advanced glycation end products (RAGE). We herein provide a wide range of information concerning their clinical application in traumatic brain injuries, Alzheimer disease, subarachnoid haemorrhage and other neurologic disorders, malignant melanoma and several other neoplasms (as S100B has been shown to down-regulate p53), as well as inflammatory diseases. Also its use on predicting neurologic outcome after resuscitation for cardiac arrest or in intrauterine growth retardation newborns is discussed.