S100B Serum Levels in Schizophrenia Are Presumably Related to Visceral Obesity and Insulin Resistance

Antipsychotic-Treated Schizophrenia Patients Develop Inflammatory and Oxidative Responses Independently From Obesity: However, Metabolic Disturbances Arise From Schizophrenia-Related Obesity

OBJECTIVE

To define the impact of obesity on inflammatory and oxidative disturbances in antipsychotic-treated schizophrenia patients.

METHODS

Several cytokines, inflammatory, metabolic, and oxidative status markers were evaluated in obese (n = 40) and non-obese (n = 40) antipsychotic-treated patients and compared with age-and BMI-matched controls (n = 80).

RESULTS

Schizophrenia patients had higher leptin, TNF-α, adiponectin, visfatin, resistin, P-selectin, NPY, BDNF, CD40-L, MCP-1, and malondialdehyde, and lower IL-6, ghrelin, neopterin, and vitamin E levels compared to their respective controls (p < 0.001). Total oxidant status was higher in non-obese patients compared to controls (p < 0.001), total antioxidant capacity was higher in obese compared to non-obese patients (p < 0.01), but vitamin A and paraoxonase levels were not different. High sensitive-CRP levels were higher in obsese controls relative to non-obese controls (p < 0.05) and in obese patients relative to non-obese patients (p < 0.001). Fasting glucose, insulin, HbA1c, HOMA-IR, uric acid, total cholesterol, and triglyceride concentrations were higher in obese patients compared to non-obese patients. Insulin concentrations and HOMA-IR were also higher in obese controls than in non-obese controls.

CONCLUSIONS

Our results suggest that inflammatory responses and oxidative stress develop independently from obesity in antipsychotic-treated schizophrenia patients. However, schizophrenia-induced obesity causes metabolic disturbances; thereby, obese schizophrenia patients are more liable to cardiovascular events and progress of metabolic syndrome than non-obese patients.

Blood Astrocyte Biomarkers in Alzheimer Disease: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Neuroinflammation, particularly early astrocyte reactivity, is a significant driver of Alzheimer disease (AD) pathogenesis. It is unclear how the levels of astrocyte biomarkers change in patients across the AD continuum and which best reflect AD-related change. We performed a systematic review and meta-analysis of 3 blood astrocyte biomarkers (glial fibrillary acidic protein [GFAP], chitinase-3-like protein 1 [YKL-40], and S100B) in patients clinically diagnosed with AD.

METHODS

MEDLINE and Web of Science were searched on March 23, 2023, without restrictions on language, time, or study design, for studies reporting blood levels of the astrocyte biomarkers GFAP, YKL-40, or S100B in patients on the AD continuum (including those with mild cognitive impairment [MCI] and dementia) and a cognitively unimpaired (CU) control population. AD diagnosis was based on established diagnostic criteria and/or comprehensive multidisciplinary clinical consensus. Studies reporting indirect biomarker measures (e.g., levels of biomarker autoantibodies) were excluded. Risk of bias assessment was performed using the revised Quality Assessment of Diagnostic Accuracy Studies tool. Pooled effect sizes were determined using the Hedge g method with a random-effects model. The review was prospectively registered on PROSPERO (registration number CRD42023458305).

RESULTS

The search identified 1,186 studies; 36 met inclusion criteria (AD continuum n = 3,366, CU n = 4,115). No study was assessed to have a high risk of bias. Compared with CU individuals, patients on the AD continuum had higher GFAP and YKL-40 levels (GFAP effect size 1.15, 95% CI 0.94-1.36, p < 0.0001; YKL-40 effect size 0.38, 95% CI 0.28-0.49, p < 0.0001). Both biomarkers were elevated in more advanced clinical stages of the disease (i.e., in AD dementia compared with MCI due to AD: GFAP effect size 0.48, 95% CI 0.19-0.76, p = 0.0009; YKL-40 effect size 0.34, 95% CI 0.10-0.57, p = 0.0048). No significant differences in blood S100B levels were identified.

DISCUSSION

We demonstrated significant elevations in blood GFAP and YKL-40 levels in patients on the AD continuum compared with CU individuals. Furthermore, within the AD clinical spectrum, significant elevation correlated with more advanced disease stage. Our findings suggest that both biomarkers reflect AD-related pathology. Our findings are limited by the lack of cultural and linguistic diversity in the study populations meta-analyzed. Future meta-analyses using a biomarker-defined AD population are warranted.

Gender differences in plasma S100B levels of patients with major depressive disorder

BACKGROUND

Low concentrations of S100B have neurotrophic effects and can promote nerve growth and repair, which plays an essential role in the pathophysiological and histopathological alterations of major depressive disorder (MDD) during disease development. Studies have shown that plasma S100B levels are altered in patients with MDD. In this study, we investigated whether the plasma S100B levels in MDD differ between genders.

METHODS

We studied 235 healthy controls (HCs) (90 males and 145 females) and 185 MDD patients (65 males and 120 females). Plasma S100B levels were detected via multifactor assay. The Mahalanobis distance method was used to detect the outliers of plasma S100B levels in the HC and MDD groups. The Kolmogorov-Smirnov test was used to test the normality of six groups of S100B samples. The Mann-Whitney test and Scheirer-Ray-Hare test were used for the comparison of S100B between diagnoses and genders, and the presence of a relationship between plasma S100B levels and demographic details or clinical traits was assessed using Spearman correlation analysis.

RESULTS

All individuals in the HC group had plasma S100B levels that were significantly greater than those in the MDD group. In the MDD group, males presented significantly higher plasma S100B levels than females. In the male group, the plasma S100B levels in the HC group were significantly higher than those in the MDD group, while in the female group, no significant difference was found between the HC and MDD groups. In the male MDD subgroup, there was a positive correlation between plasma S100B levels and years of education. In the female MDD subgroup, there were negative correlations between plasma S100B levels and age and suicidal ideation.

CONCLUSIONS

In summary, plasma S100B levels vary with gender and are decreased in MDD patients, which may be related to pathological alterations in glial cells.

Application value of serum S100B combined with glucose metabolism indexes in predicting adverse pregnancy outcomes of patients with severe preeclampsia

S100 calcium-binding protein B (S100B) and glucose control are reflective of maternal-fetal risks. We investigated the value of serum S100B combined with fasting blood glucose (FBG)/hemoglobin A1c (HbA1c) in evaluating the pregnancy outcomes of patients with severe preeclampsia (SPE). The clinical characteristics of SPE patients/controls were collected. FBG/HbA1c and serum S100B levels were measured, with their correlations analyzed. SPE patients were subdivided into adverse/non-adverse outcome groups based on follow-up results. The value of different indexes in predicting pregnancy outcomes was analyzed. SPE patients showed higher systolic blood pressure, diastolic blood pressure, urine protein, and body mass index and lower platelets, gestational age at delivery, and infant birth weight than healthy controls. FBG and HbA1c were positively correlated with serum S100B. SPE patients with adverse outcomes exhibited increased serum S100B and FBG/HbA1c levels. The area under the curve of serum S100B + FBG/HbA1c in evaluating adverse pregnancy outcomes of SPE patients was 0.8412 (77.05% sensitivity/84.21% specificity), higher than either alone. Serum S100B and FBG/HbA1c were independent risk factors for adverse outcomes of SPE patients. Overall, serum S100B positively-correlates with FBG/HbA1c in SPE patients. Serum S100B and FBG/HbA1c are independent risk factors, and their combination has high value on predicting adverse pregnancy outcomes of SPE patients.

Biochemical and Anthropometric Parameters for the Early Recognition of the Intrauterine Growth Restriction and Preterm Neonates at Risk of Impaired Neurodevelopment

BACKGROUND

S100B and Tau are implicated with both brain growth and injury. Their urinary levels in 30-to-40-day-old full-term, preterm, IUGR, and preterm-IUGR subjects were measured to investigate their possible relationship with future delayed neurodevelopment.

METHODS

Values were related to the neuro-behavioral outcome at two years of age, as well as to brain volumes and urinary NGF assessed at the same postnatal time point.

RESULTS

Using the Griffiths III test, cognitive and motor performances were determined to establish subgroups characterized by either normal or impaired neuro-behavior. The latter included preterm, IUGR, and preterm-IUGR individuals who exhibited significantly higher and lower S100B and Tau levels, respectively, along with markedly reduced cerebral volumes and urinary NGF, as previously demonstrated. Contrary to NGF, however, Tau and S100B displayed a weak correlation with brain volumes.

CONCLUSIONS

Delayed cognitive and motor performances observed in two-year-old preterm and IUGR-born individuals were also found to be associated with anomalous urinary levels of S100B and Tau, assessed at 30-40 days of the postnatal period, and their changes did not correlate with brain growth. Thus, our data suggests that, in addition to cerebral volumes and NGF, urinary S100B and Tau can also be considered as valuable parameters for the early detection of future neurodevelopmental abnormalities.

Systematic Review and Meta-Analysis of Damage Associated Molecular Patterns HMGB1 and S100B in Schizophrenia

OBJECTIVE

Immune system dysregulation is hypothesised to be central to the aetiopathogenesis of schizophrenia; however, the role of sterile inflammation remains unclear. Damage associated molecular patterns are key initiators of sterile inflammation and are detectable in peripheral blood.

METHODS

A defined systematic search of the Web of Science, PubMed, and Scopus was performed to identify adult case-control studies published between January 1990 and June 2022. Three studies consisting of 242 cases and 83 controls met inclusion for the systematic review and meta-analysis of HMGB1 while twenty-eight studies consisting of 1,544 cases and 1,248 healthy controls were included for S100B.

RESULTS

A significant standardised mean difference in peripheral S100B and HMGB1 concentrations was detected between cases and controls. S100B subgroup analysis determined the largest significant effect size for unmedicated individuals diagnosed with schizophrenia.

CONCLUSION

This study provides evidence that peripheral S100B and HMGB1 concentrations are elevated in individuals diagnosed with schizophrenia when compared with healthy controls. These results should be interpreted with caution as significant heterogeneity was present during meta-analysis of S100B in the entire sample and in sub-group analysis. The persistence of significant heterogeneity throughout subgroup analysis indicates that the current diagnostic groupings may be a barrier to understanding human behaviours and emotions.

S100B gene polymorphisms are associated with the S100B level and Alzheimer's disease risk by altering the miRNA binding capacity

To examine the role of S100B in genetic susceptibility to Alzheimer’s disease (AD), we conducted a case-control study to analyze four polymorphism loci (rs2839364, rs1051169, rs2300403, and rs9722) of the S100B gene and AD risk. We found an independent increased risk of AD in ApoE ε4(-) subjects carrying the rs9722 AA-genotype (OR = 2.622, 95% CI = 1.399–4.915, P = 0.003). Further investigation revealed the serum S100B levels to be lower in rs9722 GG carriers than in rs9722 AA carriers (P = 0.003). We identified three miRNAs (miR-340-3p, miR-593-3p, miR-6827-3p) in which the seed match region covered locus rs9722. Luciferase assays indicated that the rs9722 G allele has a higher binding affinity to miR-6827-3p than the rs9722 A allele, leading to a significantly decreased fluorescence intensity. Subsequent western blot analysis showed that the S100B protein level of SH-SY5Y cells, which carry the rs9722 G allele, decreased significantly following miR-6827-3p stimulation (P = 0.009). The present study suggests that the rs9722 polymorphism may upregulate the expression of S100B by altering the miRNA binding capacity and may thus increase the AD risk. This finding would be of great help for the early diagnosis of AD.

Targeting S100B Protein as a Surrogate Biomarker and its Role in Various Neurological Disorders

Neurological disorders (ND) are the central nervous system (CNS) related complications originated by enhanced oxidative stress, mitochondrial failure and overexpression of proteins like S100B. S100B is a helix-loop-helix protein with the calcium-binding domain associated with various neurological disorders through activation of the MAPK pathway, increased NF-kB expression resulting in cell survival, proliferation and gene up-regulation. S100B protein plays a crucial role in Alzheimer's disease, Parkinson's disease, multiple sclerosis, Schizophrenia and epilepsy because the high expression of this protein directly targets astrocytes and promotes neuroinflammation. Under stressful conditions, S100B produces toxic effects mediated through receptor for advanced glycation end products (AGE) binding. S100B also mediates neuroprotection, minimizes microgliosis and reduces the expression of tumor necrosis factor (TNF-alpha) but that are concentration- dependent mechanisms. Increased level of S100B is useful for assessing the release of inflammatory markers, nitric oxide and excitotoxicity dependent neuronal loss. The present review summarizes the role of S100B in various neurological disorders and potential therapeutic measures to reduce the prevalence of neurological disorders.

Blood-brain barrier pathology in patients with severe mental disorders: a systematic review and meta-analysis of biomarkers in case-control studies

Background

Blood-brain barrier (BBB) pathology may be associated with mental disorders. The aim of this systematic review and meta-analysis is to identify, evaluate and summarize available evidence on whether potential biomarkers of BBB pathology are altered in patients with schizophrenia spectrum disorders, major depression and bipolar disorder compared to healthy controls.

Methods

The primary outcome is blood S100B, while secondary outcomes include biomarkers in blood and/or cerebrospinal fluid, i.e. albumin ratio, fibrinogen, immunoglobulin G, glial fibrillary acidic protein, amyloid beta (Aβ), matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases, endothelial glycocalyx constituents, and cell adhesion molecules (CAMs). A systematic search in PubMed, Embase and PsycINFO resulted in 131 eligible studies, of which 93 were included in the meta-analysis. Meta- and subgroup analyses were undertaken using random-effects modelling. The protocol was a priori registered on PROSPERO (CRD42020152721).

Results

S100B was increased in schizophrenia spectrum disorders (24 studies; 1107 patients; standardized mean difference (SMD) ​= ​0.82; 95% confidence interval (CI) ​= ​0.51 to 1.13; I² ​= ​90%), major depression (13 studies; 584 patients; SMD ​= ​0.57; 95% CI ​= ​0.31 to 0.83; I² ​= ​73%) and bipolar disorder (4 studies; 142 patients; SMD ​= ​0.55; 95% CI ​= ​0.16 to 0.94; I² ​= ​48%). Similarly, numerous secondary outcomes, including albumin ratio, fibrinogen, Aβ, MMPs and CAMs, were altered. Results of the included studies varied considerably, and important confounders were often not accounted for.

Conclusions

The findings implicate occurrence of BBB pathology in patients with schizophrenia spectrum disorders, major depression and bipolar disorder compared to healthy controls. However, definite conclusions cannot be drawn, mainly because the investigated biomarkers are indirect measures of BBB pathology.

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The blood-brain barrier (BBB) can be studied indirectly through markers in blood and CSF.

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Markers of BBB pathology were altered in schizophrenia, depression and bipolar disorder.

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The findings implicate occurrence of BBB pathology in patients compared to controls.

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BBB pathology is expected to contribute to the pathogenesis of severe mental disorders.

Racial Differences in S100b Levels in Persons with Schizophrenia

The calcium-binding protein S100b is secreted by glial cells in the brain and is also expressed by melanocytes. In nanomolar concentrations, S100b is considered to be a neurotrophic factor, but in micromolar concentrations, it is thought to reflect CNS injury and inflammation. Seen as a potential biomarker in traumatic brain injury, meta-analytic data from several studies report that S100b levels are significantly higher in persons with long standing schizophrenia, but also among first-episode patients compared to healthy control subjects. However, ethnic or racial differences are typically not mentioned when reporting levels of S100b. We assessed serum S100b levels in persons with schizophrenia (n = 136) who were participants in two independent research studies using the same enzyme-linked immunoassay (ELISA). African-American subjects had significantly higher levels of S100b (41.9 pg/ml ± 62.2) than Caucasian subjects (24.9 pg/ml ± 45.4) in the combined dataset (Mann-Whitney U = 1307, p < 0.001), as well as in each independent study. There were no significant differences in S100b levels between men and women. No significant correlations were observed between S100b levels and demographic or clinical variables. These data suggest that ethnicity or race should be given serious consideration when studying and interpreting S100b levels in persons with schizophrenia.

Altered temporal sensitivity in obesity is linked to pro-inflammatory state

Temporal sensitivity to multisensory stimuli has been shown to be reduced in obesity. We sought to investigate the possible role of the pro-inflammatory state on such alteration, considering the effect of the expression of markers, such as leptin and IL6, which are notably high in obesity. The performance of 15 male individuals affected by obesity and 15 normal-weight males was compared using two audiovisual temporal tasks, namely simultaneity judgment and temporal order judgment. Analyses of serum levels of inflammatory markers of leptin and IL6, and of neurotrophic factors of BDNF and S100SB were quantified. At the behavioral level we confirmed previous evidence showing poorer temporal sensitivity in obesity compared to normal-weight participants. Furthermore, leptin, that is a cytokine overexpressed in obesity, represented the best predictor of behavioral differences between groups in both tasks. The hypothesis we put forward is that the immune system, rather than overall cerebral dysfunction, might contribute to explain the altered temporal sensitivity in obesity. The present finding is discussed within the context of the role of cytokines on the brain mechanisms supporting temporal sensitivity.

Human Aquaporin 4 Gene Polymorphisms and Haplotypes Are Associated With Serum S100B Level and Negative Symptoms of Schizophrenia in a Southern Chinese Han Population

Background: Aquaporin 4 (AQP4) polymorphism may influence the required dosage of antipsychotic drugs. However, the roles of AQP4 polymorphisms in the blood-brain barrier (BBB) and different neuroprotective effects need further exploration. This study aims to investigate whether the gene polymorphisms and haplotype of AQP4 are associated with serum S100 calcium-binding protein B (S100B) level and clinical symptoms in patients with schizophrenia (SCZ). Methods: We recruited 190 patients with SCZ. They provided demographic data, completed relevant questionnaires, and submitted samples to test for four AQP4 tag single nucleotide polymorphisms (SNPs) and eight haplotypes. The rating scales of Positive and Negative Syndrome Scale (PANSS), Personal and Social Performance (PSP), the Global Assessment of Functioning (GAF), Clinical Global Impression (CGI) were assessed and serum S100B level were measured repeatedly during antipsychotic treatment at weeks 0 (baseline), 3, 6, and 9. Using generalized estimating equation (GEE) analyses, log-transformed S100B (logS100B) level was tested for associations with haplotype and other dependent variables. Results: Discretization via the median split procedure showed that logS100B level >1.78 or ≤ 1.78 had the best discriminant validity to stratify the patients into two groups. After 9 weeks of treatment, the serum S100B level was decreased. The TAA haplotype of AQP4 SNPs was associated with increased serum S100B level (p = 0.006). The PANSS negative subscale (PANSS-N) (p = 0.001) and Clinical Global Impression-Improvement (CGI-I) (p = 0.003) scores had a positive association with S100B level. Conclusion: Patients with the TAA haplotype of the AQP4 polymorphism are likely to have increased serum S100B level, negative symptoms and poor control of neuroinflammation. A logS100B level >1.78 may be sufficiently specific to predict a higher severity of negative symptoms. Further study including healthy controls and patients with first and recurrent episodes under selective AQP4 modulators will be necessary to explore the profound effects on the treatment of patients with SCZ and may positively influence their overall outcome.

Biomarkers in traumatic brain injury (TBI): a review

Biomarkers can be broadly defined as qualitative or quantitative measurements that convey information on the physiopathological state of a subject at a certain time point or disease state. Biomarkers can indicate health, pathology, or response to treatment, including unwanted side effects. When used as outcomes in clinical trials, biomarkers act as surrogates or substitutes for clinically meaningful endpoints. Biomarkers of disease can be diagnostic (the identification of the nature and cause of a condition) or prognostic (predicting the likelihood of a person's survival or outcome of a disease). In addition, genetic biomarkers can be used to quantify the risk of developing a certain disease. In the specific case of traumatic brain injury, surrogate blood biomarkers of imaging can improve the standard of care and reduce the costs of diagnosis. In addition, a prognostic role for biomarkers has been suggested in the case of post-traumatic epilepsy. Given the extensive literature on clinical biomarkers, we will focus herein on biomarkers which are present in peripheral body fluids such as saliva and blood. In particular, blood biomarkers, such as glial fibrillary acidic protein and salivary/blood S100B, will be discussed together with the use of nucleic acids (eg, DNA) collected from peripheral cells.

S100B impairs glycolysis via enhanced poly(ADP-ribosyl)ation of glyceraldehyde-3-phosphate dehydrogenase in rodent muscle cells

S100 calcium-binding protein B (S100B), a multifunctional macromolecule mainly expressed in nerve tissues and adipocytes, has been suggested to contribute to the pathogenesis of obesity. To clarify the role of S100B in insulin action and glucose metabolism in peripheral tissues, we investigated the effect of S100B on glycolysis in myoblast and myotube cells. Rat myoblast L6 cells were treated with recombinant mouse S100B to examine glucose consumption, lactate production, glycogen accumulation, glycolytic metabolites and enzyme activity, insulin signaling, and poly(ADP-ribosyl)ation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Glycolytic metabolites were investigated by enzyme assays or metabolome analysis, and insulin signaling was assessed by Western blot analysis. Enzyme activity and poly(ADP-ribosyl)ation of GAPDH was evaluated by an enzyme assay and immunoprecipitation followed by dot blot with an anti-poly(ADP-ribose) antibody, respectively. S100B significantly decreased glucose consumption, glucose analog uptake, and lactate production in L6 cells, in either the presence or absence of insulin. In contrast, S100B had no effect on glycogen accumulation and insulin signaling. Metabolome analysis revealed that S100B increased the concentration of glycolytic intermediates upstream of GAPDH. S100B impaired GAPDH activity and increased poly(ADP-ribosyl)ated GAPDH proteins. The effects of S100B on glucose metabolism were mostly canceled by a poly(ADP-ribose) polymerase inhibitor. Similar results were obtained in C₂C₁₂ myotube cells. We conclude that S100B as a humoral factor may impair glycolysis in muscle cells independent of insulin action, and the effect may be attributed to the inhibition of GAPDH activity from enhanced poly(ADP-ribosyl)ation of the enzyme.

Serum S100B Is Related to Illness Duration and Clinical Symptoms in Schizophrenia-A Meta-Regression Analysis

S100B has been linked to glial pathology in several psychiatric disorders. Previous studies found higher S100B serum levels in patients with schizophrenia compared to healthy controls, and a number of covariates influencing the size of this effect have been proposed in the literature. Here, we conducted a meta-analysis and meta-regression analysis on alterations of serum S100B in schizophrenia in comparison with healthy control subjects. The meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to guarantee a high quality and reproducibility. With strict inclusion criteria 19 original studies could be included in the quantitative meta-analysis, comprising a total of 766 patients and 607 healthy control subjects. The meta-analysis confirmed higher values of the glial serum marker S100B in schizophrenia if compared with control subjects. Meta-regression analyses revealed significant effects of illness duration and clinical symptomatology, in particular the total score of the Positive and Negative Syndrome Scale (PANSS), on serum S100B levels in schizophrenia. In sum, results confirm glial pathology in schizophrenia that is modulated by illness duration and related to clinical symptomatology. Further studies are needed to investigate mechanisms and mediating factors related to these findings.

Negative Correlation between Serum S100B and Leptin Levels in Schizophrenic Patients During Treatment with Clozapine and Risperidone: Preliminary Evidence

Recently, extensive efforts have been made to understand the rate of energy expenditure and the weight gain associated with atypical antipsychotic treatment, including identification of markers of obesity risk. In recent years, leptin, an adipocyte hormone, has gained significant interest in psychiatric disorders. S100B has been considered as a surrogate marker for astrocyte-specific damage in neurologic disorders. Also, S100B has been detected in adipose with concentration as high as nervous tissue as a second release source. In this study we evaluated the relationship between S100B and leptin in schizophrenic patients under treatment with clozapine and risperidone.This study included 19 patients meeting the DSM-IV-TR criteria for schizophrenia, having body mass index (BMI) of 16- 25 kg/m(2) and suffering schizophrenia for more than 3 years and from this study. Twenty five healthy controls were group matched for age and gender whose BMI was 16-25 kg/m(2). Serum S100B and leptin levels and positive and negative symptom scale (PANSS) were assessed at admission and after six weeks. During the study, S100B showed a strong and negative correlation with leptin (r = -0.5, P = 0.01). Also, there were negative correlation between serum S100B level and PANSS negative subscale after 6 weeks of treatment (r = -0.048, P = 0.8). Positive correlation between leptin level and PANSS suggested a potential role for leptin which can mediate the link between antipsychotic induced weight gain and therapeutic response in schizophrenia.

Label-free profiling of white adipose tissue of rats exhibiting high or low levels of intrinsic exercise capacity

Divergent selection has created rat phenotypes of high- and low-capacity runners (HCR and LCR, respectively) that have differences in aerobic capacity and correlated traits such as adiposity. We analyzed visceral adipose tissue of HCR and LCR using label-free high-definition MS (elevated energy) profiling. The running capacity of HCR was ninefold greater than LCR. Proteome profiling encompassed 448 proteins and detected 30 significant (p <0.05; false discovery rate <10%, calculated using q-values) differences. Approximately half of the proteins analyzed were of mitochondrial origin, but there were no significant differences in the abundance of proteins involved in aerobic metabolism. Instead, adipose tissue of LCR rats exhibited greater abundances of proteins associated with adipogenesis (e.g. cathepsin D), ER stress (e.g. 78 kDa glucose response protein), and inflammation (e.g. Ig gamma-2B chain C region). Whereas the abundance antioxidant enzymes such as superoxide dismutase [Cu-Zn] was greater in HCR tissue. Putative adipokines were also detected, in particular protein S100-B, was 431% more abundant in LCR adipose tissue. These findings reveal low running capacity is associated with a pathological profile in visceral adipose tissue proteome despite no detectable differences in mitochondrial protein abundance.

Elevated levels of cerebrospinal fluid neuron-specific enolase (NSE), but not S100B in major depressive disorder

OBJECTIVES

Alterations in neuronal and glial integrity are considered to be of pathogenic impact on major depressive disorder (MDD). For MDD, data on cerebrospinal fluid (CSF) levels of neuron-specific enolase (NSE) are lacking and scarce for glial protein S100B.

METHODS

We measured CSF levels of NSE and S100B in 31 patients with MDD and 32 mentally healthy controls using electrochemiluminescence immunoassays (ECLIA).

RESULTS

Adjusted means of NSE were significantly elevated in the MDD patients (11.73 ng/ml (9.95-13.52 95% CI) compared to the controls (6.17 ng/ml (4.55-7.78), F = 9.037, P = 0.004. Effect size for adjusted mean group difference of 5.57 ng/ml was found invariably high (Cohen's d = 1.23). Differentiating MDD from controls, a NSE cut-off of 7.94 ng/ml showed sensitivity of 81% (95% CI 63.7-90.8) and specificity of 75% (95% CI 57.9-86.7). Adjusted levels of S100B did not differ significantly between the two groups (1.12 ng/ml (0.77-1.48) in MDD, 0.97 ng/ml (0.64-1.30) in controls).

CONCLUSIONS

Our results of elevated CSF-NSE levels support neuronal pathology in MDD and the potential use of CSF-NSE as marker in clinical diagnostics. Missing group differences in S100B do not promote a specific glial pathology in depressive disorders.

Systematic review and meta-analysis of circulating S100B blood levels in schizophrenia

S100B is a calcium-binding protein secreted in central nervous system from astrocytes and other glia cells. High blood S100B levels have been linked to brain damage and psychiatric disorders. S100B levels have been reported to be higher in schizophrenics than healthy controls. To quantify the relationship between S100B blood levels and schizophrenia a systematic literature review of case-control studies published on this topic within July 3rd 2014 was carried out using three bibliographic databases: Medline, Scopus and Web of Science. Studies reporting mean and standard deviation of S100B blood levels both in cases and controls were included in the meta-analysis. The meta-Mean Ratio (mMR) of S100B blood levels in cases compared to controls was used as a measure of effect along with its 95% Confidence Intervals (CI). 20 studies were included totaling for 994 cases and 785 controls. Schizophrenia patients showed 76% higher S100B blood levels than controls with mMR = 1.76 95% CI: 1.44-2.15. No difference could be found between drug-free patients with mMR = 1.84 95%CI: 1.24-2.74 and patients on antipsychotic medication with mMR = 1.75 95% CI: 1.41-2.16). Similarly, ethnicity and stage of disease didn't affect results. Although S100B could be regarded as a possible biomarker of schizophrenia, limitations should be accounted when interpreting results, especially because of the high heterogeneity that remained >70%, even after carrying out subgroups analyses. These results point out that approaches based on traditional categorical diagnoses may be too restrictive and new approaches based on the characterization of new complex phenotypes should be considered.

Regulation of S100B in white adipose tissue by obesity in mice

S100B is a calcium binding protein found in adipose tissue; however, relatively little is known about the physiologic regulation or distribution of the protein within this organ. We examined plasma S100B concentration and white adipose tissue (WAT) s100b mRNA levels in lean and diet-induced obese (DIO) mice. Plasma S100B levels were increased by obesity. In WAT, s100b gene expression was also significantly increased by obesity and this increase was reversed following weight-loss. s100b gene expression was detected in both the adipocyte-enriched and stromal-vascular fractions of WAT; however, the increase in s100b gene expression in obese animals was only detected in the adipocyte-enriched fraction. Our results support published in vitro data indicating that WAT S100B may contribute to obesity-associated inflammation.

The role of S100B in the interaction between adipocytes and macrophages

OBJECTIVE

The S100 calcium binding protein B (S100B) implicated in brain inflammation acts via the receptor of advanced glycation end products (RAGE) and is also secreted from adipocytes. We investigated the role of S100B in the interaction between adipocytes and macrophages using a cell-culture model.

DESIGN AND METHODS

RAW264.7 macrophages (RAW) were stimulated by recombinant S100B to observe alterations in TNF-α and M1 markers; 3T3-L1 adipocytes (L1) were stimulated by TNF-α to examine S100B secretion. RAW and L1 were then mutually stimulated with conditioned media of each other, or co-cultured. The effects of S100B silencing or a RAGE-neutralizing antibody were also investigated.

RESULTS

S100B upregulated TNF-α and M1 markers in RAW, and TNF-α augmented S100B secretion from L1. L1 conditioned media stimulated TNF-α secretion from RAW, and RAW conditioned media increased S100B secretion from L1. The co-culture of RAW and L1 increased TNF-α, S100B, and the expression of M1 markers and the MCP-1 receptor CCR2. The silencing of S100B or RAGE neutralization significantly ameliorated TNF-α hypersecretion from RAW that were stimulated with L1 conditioned media.

CONCLUSIONS

Thus, S100B as an adipokine may play a role in the interaction between adipocytes and macrophages to establish a vicious paracrine loop.

Replicated evidence of absence of association between serum S100B and (risk of) psychotic disorder

BACKGROUND

S100B is a potential marker of neurological and psychiatric illness. In schizophrenia, increased S100B levels, as well as associations with acute positive and persisting negative symptoms, have been reported. It remains unclear whether S100B elevation, which possibly reflects glial dysfunction, is the consequence of disease or compensatory processes, or whether it is an indicator of familial risk.

METHODS

Serum samples were acquired from two large independent family samples (n = 348 and n = 254) in the Netherlands comprising patients with psychotic disorder (n = 140 and n = 82), non-psychotic siblings of patients with psychotic disorder (n = 125 and n = 94) and controls (n = 83 and n = 78). S100B was analyzed with a Liaison automated chemiluminescence system. Associations between familial risk of psychotic disorder and S100B were examined.

RESULTS

Results showed that S100B levels in patients (P) and siblings (S) were not significantly different from controls (C) (dataset 1: P vs. C: B = 0.004, 95% CI -0.005 to 0.013, p = 0.351; S vs. C: B = 0.000, 95% CI -0.009 to 0.008, p = 0.926; and dataset 2: P vs. C: B = 0.008, 95% CI -0.011 to 0.028, p = 0.410; S vs. C: B = 0.002, 95% CI -0.016 to 0.021, p = 0.797). In patients, negative symptoms were positively associated with S100B (B = 0.001, 95% CI 0.000 to 0.002, p = 0.005) in one of the datasets, however with failure of replication in the other. There was no significant association between S100B and positive symptoms or present use or type of antipsychotic medication.

CONCLUSIONS

S100B is neither an intermediate phenotype, nor a trait marker for psychotic illness.

The neuroimmunology of schizophrenia

Schizophrenia (SCZ) is a polygenic, multi-factorial disorder and a definitive understanding of its pathophysiology has been lacking since it was first described more than a century ago. The predominant pharmacological approach used to treat SCZ is the use of dopamine receptor antagonists. The fact that many patients remain symptomatic, despite complying with medication regimens, emphasises the need for a more encompassing explanation for both the causes and treatment of SCZ. Recent neuroanatomical, neurobiological, environmental and genetic studies have revived the idea that inflammatory pathways are involved in the pathogenesis of SCZ. These new insights have emerged from multiple lines of evidence, including the levels of inflammatory proteins in the central nervous system of patients with SCZ and animal models. This review focuses on aberrant inflammatory mechanisms present both before and during the onset of the psychotic symptoms that characterise SCZ and discusses recent research into adjunctive immune system modulating therapies for its more effective treatment.

Interleukin-6-induced S100B secretion is inhibited by haloperidol and risperidone

Although inflammation may be a physiological defense process, imbalanced neuroinflammation has been associated with the pathophysiology of brain disorders, including major depression and schizophrenia. Activated glia releases a variety of pro-inflammatory cytokines that contribute to neuronal dysfunction. Elevated levels of S100B, a glia derived protein, have been observed in the serum and CSF of schizophrenic patients suggesting a glial role in the disease. We evaluated whether S100B secretion (in C6 glioma cells and hippocampal slices in Wistar rats) could be directly modulated by the main inflammatory cytokines (IL-1β, TNF-α, IL-6 and IL-8) altered in schizophrenia, as well as the possible involvement of mitogen-activated protein kinase (MAPK) pathways in these responses. We also investigated the effects of typical and atypical antipsychotic drugs on glial cytokine-induced S100B release. Our results suggest that S100B secretion is increased by pro-inflammatory cytokines via MAPK and that oxidative stress may be a component of this modulation. These results reinforce the idea that the S100B protein is involved in the inflammatory response observed in many brain diseases, including schizophrenia. Moreover the antipsychotics, haloperidol and risperidone, were able to inhibit the secretion of S100B following IL-6 stimulation in C6 glioma cells.

Levels of S100B are raised in female patients with schizophrenia

BACKGROUND

The neurotrophic factor, S100B, is released primarily from astrocytes, with serum and CSF levels of S100B reported as altered in schizophrenia. However, many of these reports are contradictory. Here, serum levels of S100B in schizophrenia and influence of age, gender, medication and illness severity were examined.

METHODS

Serum S100B levels were measured in patients with schizophrenia treated with clozapine. Lifestyle, metabolic and illness severity parameters were correlated with S100B concentrations.

RESULTS

Data showed raised serum levels of S100B in schizophrenia female patients, but not male patients, compared to controls. Correlation analysis demonstrated a positive association between S100B serum concentrations and BMI.

CONCLUSIONS

This study supports previous findings that adipocytes may contribute to S100B serum concentrations in females, in addition to astrocytes. This study also supports the hypothesis that metabolic effects of medication, lifestyle choices and the illness itself, may be contributing factors to altered levels of S100B.