S100B in brain damage and neurodegeneration

Psychological and cognitive impairment of long-term migrators to high altitudes and the relationship to physiological and biochemical changes

BACKGROUND AND PURPOSE

The present study aimed to examine how long-term migration to high-altitude regions affects mentality and cognition, and the correlation with various physiological and biochemical changes.

METHODS

The WHO Neurobehavioral Core Test Battery, Raven's Standard Progressive Matrices (RSPM) and Pittsburgh Sleep Quality Index questionnaire were used to assess 141 young male subjects who lived in plain regions and 217 young male subjects who had migrated to a 4500 m high-altitude region and lived there for 1-5 years. Arterial oxyhemoglobin saturation, cerebral tissue oxygenation indices (TOIs), serum S100B and brain-derived neurotrophic factor (BDNF) were also measured.

RESULTS

Long-term migrators to a high-altitude region exhibited exacerbated mood disorders, retarded color discrimination ability, decreased visual memory capacity, and impaired perceptual motor skill and motion stability. In addition, the migrators exhibited lower RSPM scores and lower sleep quality. Further analyses revealed significant correlations between sleep quality and cerebral TOIs, mood and sleep quality, mood and certain cognitive functions, mood and serum BDNF levels, and RSPM scores and serum S100B levels.

CONCLUSIONS

Long-term living at high altitudes causes significant impairment of psychological and cognitive function. Cerebral hypoxic extent, sleep quality and biochemical dysfunction are major influencing factors.

Is peripheral immunity regulated by blood-brain barrier permeability changes?

S100B is a reporter of blood-brain barrier (BBB) integrity which appears in blood when the BBB is breached. Circulating S100B derives from either extracranial sources or release into circulation by normal fluctuations in BBB integrity or pathologic BBB disruption (BBBD). Elevated S100B matches the clinical presence of indices of BBBD (gadolinium enhancement or albumin coefficient). After repeated sub-concussive episodes, serum S100B triggers an antigen-driven production of anti-S100B autoantibodies. We tested the hypothesis that the presence of S100B in extracranial tissue is due to peripheral cellular uptake of serum S100B by antigen presenting cells, which may induce the production of auto antibodies against S100B. To test this hypothesis, we used animal models of seizures, enrolled patients undergoing repeated BBBD, and collected serum samples from epileptic patients. We employed a broad array of techniques, including immunohistochemistry, RNA analysis, tracer injection and serum analysis. mRNA for S100B was segregated to barrier organs (testis, kidney and brain) but S100B protein was detected in immunocompetent cells in spleen, thymus and lymph nodes, in resident immune cells (Langerhans, satellite cells in heart muscle, etc.) and BBB endothelium. Uptake of labeled S100B by rat spleen CD4+ or CD8+ and CD86+ dendritic cells was exacerbated by pilocarpine-induced status epilepticus which is accompanied by BBBD. Clinical seizures were preceded by a surge of serum S100B. In patients undergoing repeated therapeutic BBBD, an autoimmune response against S100B was measured. In addition to its role in the central nervous system and its diagnostic value as a BBBD reporter, S100B may integrate blood-brain barrier disruption to the control of systemic immunity by a mechanism involving the activation of immune cells. We propose a scenario where extravasated S100B may trigger a pathologic autoimmune reaction linking systemic and CNS immune responses.

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.

MLC901, a Traditional Chinese Medicine induces neuroprotective and neuroregenerative benefits after traumatic brain injury in rats

Traumatic brain injury (TBI) is a frequent and clinically highly heterogeneous neurological disorder with large socioeconomic consequences. NeuroAid (MLC601 and MLC901), a Traditional Medicine used in China for patients after stroke has been previously reported to induce neuroprotection and neuroplasticity. This study was designed to evaluate the neuroprotective and neuroregenerative effects of MLC901 in a rat model of TBI. TBI was induced by a moderate lateral fluid percussion applied to the right parietal cortex. MLC901 was injected intraperitoneally at 2h post-TBI, and then administered in drinking water at a concentration of 10mg/ml until sacrifice of the animals. The cognitive deficits induced by TBI were followed by using the "what-where-when" task, which allows the measurement of episodic-like memory. MLC901 treatment decreased brain lesions induced by TBI. It prevented the serum increase of S-100 beta (S100B) and neuron-specific enolase (NSE), which may be markers to predict the neurologic outcome in human patients with TBI. MLC901 reduced the infarct volume when injected up to 2h post-TBI, prevented edema formation and assisted its resolution, probably via the regulation of aquaporin 4. These positive MLC901 effects were associated with an upregulation of vascular endothelial growth factor (VEGF) as well as an increase of endogenous hippocampal neurogenesis and gliogenesis around the lesion. Furthermore, MLC901 reduced cognitive deficits induced by TBI. Rats subjected to TBI displayed a suppression of temporal order memory, which was restored by MLC901. This work provides evidence that MLC901 has neuroprotective and neurorestorative actions, which lead to an improvement in the recovery of cognitive functions in a model of traumatic brain injury.

The use of cytokine signature patterns: separating drug naïve, interferon and natalizumab-treated multiple sclerosis patients

Multiple sclerosis (MS) is an inflammatory illness characterized by demyelination and axonal neurodegeneration. Here, we used serum samples from MS patients to demonstrate if "cytokine signature" patterns can separate different patient groups better than using single cytokines. In this case, we used cytokine profiling to demonstrate if "cytokine signature" patterns can separate MS patients treated with interferon or natalizumab from drug naïve patients. Serum levels of eight individual cytokines (TNFα, IFNγ, S100B, IL-1β, IL-6, IL-8, IL-17 and IL-23) in MS patients treated with interferons (n = 11) and natalizumab (n = 14) were measured and, in general, showed reduced levels compared to drug naïve MS patients (n = 12). More evident changes were seen when analyzing "cytokine signatures" (i.e. summed value of all eight cytokines), which showed that patients treated with natalizumab and interferons showed significantly reduced cytokine signature levels than drug naïve MS patients. Moreover, patients treated with natalizumab were separated from drug naïve patients by almost 100% fidelity and that patients treated with natalizumab also had reduced levels of pro-inflammatory cytokines compared to patients treated with interferon. Overall, this study provides an example showing that the use of "cytokine signatures" may provide benefits over the analysis of single cytokines for the development of potential biomarkers.

Voltammetric detection of S100B protein using His-tagged receptor domains for advanced glycation end products (RAGE) immobilized onto a gold electrode surface

In this work we report on an electrochemical biosensor for the determination of the S100B protein. The His-tagged VC1 domains of Receptors for Advanced Glycation End (RAGE) products used as analytically active molecules were covalently immobilized on a monolayer of a thiol derivative of pentetic acid (DPTA) complex with Cu(II) deposited on a gold electrode surface. The recognition processes between the RAGE VC1 domain and the S100B protein results in changes in the redox activity of the DPTA-Cu(II) centres which were measured by Osteryoung square-wave voltammetry (OSWV). In order to verify whether the observed analytical signal originates from the recognition process between the His₆–RAGE VC1 domains and the S100B protein, the electrode modified with the His₆–RAGE C2 and His₆–RAGE VC1 deleted domains which have no ability to bind S100B peptides were applied. The proposed biosensor was quite sensitive, with a detection limit of 0.52 pM recorded in the buffer solution. The presence of diluted human plasma and 10 nM Aβ_1-40 have no influence on the biosensor performance.

S100B is downregulated in the nuclear proteome of schizophrenia corpus callosum

Here we report the downregulation of S100B in the nuclear proteome of the corpus callosum from nine schizophrenia patients compared to seven mentally healthy controls. Our data have been obtained primarily by mass spectrometry and later confirmed by Western blot. This is an intriguing finding coming from a brain region which is essentially composed by white matter, considering the potential role of S100B in the control of oligodendrocyte maturation. This data reinforce the importance of oligodendrocytes in schizophrenia, shedding more light to its pathobiology.

Electroacupuncture-like stimulation at the Baihui (GV20) and Dazhui (GV14) acupoints protects rats against subacute-phase cerebral ischemia-reperfusion injuries by reducing S100B-mediated neurotoxicity

Objectives

The purpose of this study was to evaluate the effects of electroacupuncture-like stimulation at the Baihui (GV20) and Dazhui (GV14) acupoints (EA at acupoints) during the subacute phase of cerebral ischemia-reperfusion (I/R) injury and to establish the neuroprotective mechanisms involved in the modulation of the S100B-mediated signaling pathway.

Methods

The experimental rats were subjected to middle cerebral artery occlusion (MCAo) for 15 min followed by 1 d or 7 d of reperfusion. EA at acupoints was applied 1 d postreperfusion then once daily for 6 consecutive days.

Results

We observed that 15 min of MCAo caused delayed infarct expansion 7 d after reperfusion. EA at acupoints significantly reduced the cerebral infarct and neurological deficit scores. EA at acupoints also downregulated the expression of the glial fibrillary acidic protein (GFAP), S100B, nuclear factor-κB (NF-κB; p50), and tumor necrosis factor-α (TNF-α), and reduced the level of inducible nitric oxide synthase (iNOS) and apoptosis in the ischemic cortical penumbra 7 d after reperfusion. Western blot analysis showed that EA at acupoints significantly downregulated the cytosolic expression of phospho-p38 MAP kinase (p-p38 MAP kinase), tumor necrosis factor receptor type 1-associated death domain (TRADD), Fas-associated death domain (FADD), cleaved caspase-8, and cleaved caspase-3 in the ischemic cortical penumbra 7 d after reperfusion. EA at acupoints significantly reduced the numbers of GFAP/S100B and S100B/nitrotyrosine double-labeled cells.

Conclusion

Our study results indicate that EA at acupoints initiated 1 d postreperfusion effectively downregulates astrocytic S100B expression to provide neuroprotection against delayed infarct expansion by modulating p38 MAP kinase-mediated NF-κB expression. These effects subsequently reduce oxidative/nitrative stress and inhibit the TNF-α/TRADD/FADD/cleaved caspase-8/cleaved caspase-3 apoptotic pathway in the ischemic cortical penumbra 7 d after reperfusion.

Oxygen-induced retinopathy induces short-term glial stress and long-term impairment of photoentrainment in mice

BACKGROUND

Retinopathy of prematurity is a serious potentially blinding disease of pre-term infants. There is extensive vascular remodeling and tissue stress, but data concerning alterations in retinal neurons and glia, and long-term functional sequelae are still incomplete.

METHODS

ROP was induced using the oxygen-induced retinopathy (OIR) mouse model. Postnatal day 7 (P7) 129SVE mice were exposed to hyperoxia (75 ± 0.5 % oxygen) for 5 days, and then returned to normoxia to induce OIR. Exposed animals were euthanized at 5 (P17-OIR) and 14 days (P26-OIR) after return to normal air, together with corresponding age-matched control mice (P17-C and P26-C respectively) raised only in room air. Their retinas were examined by immunohistochemistry using a battery of antibodies against key glial and neuronal proteins. A further group of OIR mice and controls were examined at 10 weeks of age for their ability to re-entrain to changing 12 h light/12 h dark cycles, assayed by wheel-running actimetry. In this protocol, animals were subjected to three successive conditions of 300 lux, 15 lux and 1 lux ambient light intensity coupled with 6 hours of jetlag. Animals were euthanized at 4 months of age and used in immunoblotting for rhodopsin.

RESULTS

Compared to P17-C, immunohistochemical staining of P17-OIR sections showed up-regulation of stress-related and glutamate-regulatory proteins in astrocytes and Müller glial cells. In contrast, glial phenotypic expression in P26-OIR retinas largely resembled that in P26-C. There was no loss in total retinal ganglion cells (RGC) at either P17-OIR or P26-OIR compared to corresponding controls, whereas intrinsically photosensitive RGC showed significant decreases, with 375 ± 13/field in P26-OIR compared to 443 ± 30/field in P26-C (p < 0.05). Wheel actimetry performed on control and OIR-treated mice at 4 months demonstrated that animals raised in hyperoxic conditions had impaired photoentrainment at low illuminance of 1 lux, as well as significantly reduced levels of rhodopsin compared to age-matched controls.

CONCLUSIONS

OIR leads to transient up-regulation of retinal glial proteins involved in metabolism, and partial degeneration of intrinsically photosensitive RGC and rod photoreceptors. OIR affects circadian photo-entrainment at low illuminance values, possibly by affecting the rod pathway and/or intrinsically photosensitive RGC input to the circadian clock. This study hence shows that retinopathy of prematurity affects light-regulated circadian behavior in an animal model, and may induce similar problems in humans.

Decrease of serum S100B during an oral glucose tolerance test correlates inversely with the insulin response

Increased S100B serum levels have been considered as a marker of glial pathology, brain damage, and blood-brain-barrier impairment. However, S100B expression has also been detected outside the nervous system, suggesting that altered S100B serum levels may not exclusively reflect brain-specific pathologies. Notably, S100B secretion in adipocytes seems to be down-regulated by insulin, and up-regulated by stress and fasting. Therefore, we assumed that dynamic changes of S100B could be observed by challenging healthy subjects with an oral glucose tolerance test (OGTT). OGTT was performed in 17 healthy adult test persons (9 male and 8 female). Apart from S100B, glucose, free fatty acids, insulin, C-peptide, and cortisol were determined in all samples after an overnight fast (0 h), as well as 1h and 2h after ingestion of 75 g glucose. Mean S100B concentrations decreased about 20% during the first hour after glucose ingestion (P<0.001). This decrease of S100B levels was not related to the declining morning peak of cortisol. However, the decrease of serum-S100B 1h after glucose ingestion correlated inversely with the respective changes of serum-insulin (r = -0.484, P=0.049) and serum-C-peptide (r = -0.570, P = 0.017). Our study suggests an inverse correlation between insulin secretion and S100B release after a standardized OGTT. Additional experiments, including the administration of insulin and the measurement of other food intake-related factors are important to ascertain an insulin-regulated S100B release in vivo. To improve comparability between clinical studies assessing conditions with rather mild changes of serum S100B, blood should be taken in a more standardized way (e.g., after fasting overnight).

Biomarkers for the diagnosis and prognosis of mild traumatic brain injury/concussion

Mild traumatic brain injury (mTBI) results from a transfer of mechanical energy into the brain from traumatic events such as rapid acceleration/deceleration, a direct impact to the head, or an explosive blast. Transfer of energy into the brain can cause structural, physiological, and/or functional changes in the brain that may yield neurological, cognitive, and behavioral symptoms that can be long-lasting. Because mTBI can cause these symptoms in the absence of positive neuroimaging findings, its diagnosis can be subjective and often is based on self-reported neurological symptoms. Further, proper diagnosis can be influenced by the motivation to conceal or embellish signs and/or an inability of the patient to notice subtle dysfunctions or alterations of consciousness. Therefore, appropriate diagnosis of mTBI would benefit from objective indicators of injury. Concussion and mTBI are often used interchangeably, with concussion being primarily used in sport medicine, whereas mTBI is used in reference to traumatic injury. This review provides a critical assessment of the status of current biomarkers for the diagnosis of human mTBI. We review the status of biomarkers that have been tested in TBI patients with injuries classified as mild, and introduce a new concept for the discovery of biomarkers (termed symptophenotypes) to predict common and unique symptoms of concussion. Finally, we discuss the need for biomarker/biomarker signatures that can detect mTBI in the context of polytrauma, and to assess the consequences of repeated injury on the development of secondary injury syndrome, prolongation of post-concussion symptoms, and chronic traumatic encephalopathy.

Glial A30P alpha-synuclein pathology segregates neurogenesis from anxiety-related behavior in conditional transgenic mice

In Parkinson's disease (PD) patients, alpha-synuclein (α-syn) pathology advances in form of Lewy bodies and Lewy neurites throughout the brain. Clinically, PD is defined by motor symptoms that are predominantly attributed to the dopaminergic cell loss in the substantia nigra. However, motor deficits are frequently preceded by smell deficiency or neuropsychological symptoms, including increased anxiety and cognitive dysfunction. Accumulating evidence indicates that aggregation of α-syn impairs synaptic function and neurogenic capacity that may be associated with deficits in memory, learning and mood. Whether and how α-syn accumulation contributes to neuropathological events defining these earliest signs of PD is presently poorly understood. We used a tetracycline-suppressive (tet-off) transgenic mouse model that restricts overexpression of human A30P α-syn to neurons owing to usage of the neuron-specific CaMKIIα promoter. Abnormal accumulation of A30P correlated with a decreased survival of newly generated neurons in the hippocampus and olfactory bulb. Furthermore, when A30P α-syn expression was suppressed, we observed reduction of the human protein in neuronal soma. However, residual dox resistant A30P α-syn was detected in glial cells within the hippocampal neurogenic niche, concomitant with the failure to fully restore hippocampal neurogenesis. This finding is indicative to a potential spread of pathology from neuron to glia. In addition, mice expressing A30P α-syn show increased anxiety-related behavior that was reversed after dox treatment. This implies that glial A30P α-synucleinopathy within the dentate gyrus is part of a process leading to impaired hippocampal neuroplasticity, which is, however, not a sole critical event for circuits implicated in anxiety-related behavior.

S100B overexpression increases behavioral and neural plasticity in response to the social environment during adolescence

Genetic variants as well as increased serum levels of the neurotrophic factor S100B are associated with different psychiatric disorders. However, elevated S100B levels are also related to a better therapeutic outcome in psychiatric patients. The functional role of elevated S100B in psychiatric disorders is still unclear. Hence, this study was designed in order to elucidate the differential effects of S100B overexpression in interaction with chronic social stress during adolescence on emotional behavior and adult neurogenesis. S100B transgenic and wild-type mice were housed either in socially stable or unstable environments during adolescence, between postnatal days 28 and 77. In adulthood, anxiety-related behavior in the open field, dark-light, and novelty-induced suppression of feeding test as well as survival of proliferating hippocampal progenitor cells were assessed. S100B transgenic mice revealed significantly reduced anxiety-related behavior in the open field compared to wild-types when reared in stable social conditions. In contrast, when transgenic mice grew up in unstable social conditions, their level of anxiety-related behavior was comparable to the levels of wild-type mice. In addition, S100B overexpressing mice from unstable housing conditions displayed higher numbers of surviving newborn cells in the adult hippocampus which developed into mature neurons. In conclusion, elevated S100B levels increase the susceptibility to environmental stimuli during adolescence resulting in more variable behavioral and neural phenotypes in adulthood. In humans, this increased plasticity might lead to both, enhanced risk for psychiatric disorders in negative environments and improved therapeutic outcome in positive environments.

Astrocyte pathology in major depressive disorder: insights from human postmortem brain tissue

The present paper reviews astrocyte pathology in major depressive disorder (MDD) and proposes that reductions in astrocytes and related markers are key features in the pathology of MDD. Astrocytes are the most numerous and versatile of all types of glial cells. They are crucial to the neuronal microenvironment by regulating glucose metabolism, neurotransmitter uptake (particularly for glutamate), synaptic development and maturation and the blood brain barrier. Pathology of astrocytes has been consistently noted in MDD as well as in rodent models of depressive-like behavior. This review summarizes evidence from human postmortem tissue showing alterations in the expression of protein and mRNA for astrocyte markers such as glial fibrillary acidic protein (GFAP), gap junction proteins (connexin 40 and 43), the water channel aquaporin-4 (AQP4), a calcium-binding protein S100B and glutamatergic markers including the excitatory amino acid transporters 1 and 2 (EAAT1, EAAT2) and glutamine synthetase. Moreover, preclinical studies are presented that demonstrate the involvement of GFAP and astrocytes in animal models of stress and depressive-like behavior and the influence of different classes of antidepressant medications on astrocytes. In light of the various astrocyte deficits noted in MDD, astrocytes may be novel targets for the action of antidepressant medications. Possible functional consequences of altered expression of astrocytic markers in MDD are also discussed. Finally, the unique pattern of cell pathology in MDD, characterized by prominent reductions in the density of astrocytes and in the expression of their markers without obvious neuronal loss, is contrasted with that found in other neuropsychiatric and neurodegenerative disorders.

Genetic analysis of the S100B gene in Chinese patients with Parkinson disease

There is growing evidence that genetic abnormalities play an important role in the pathogenesis of Parkinson disease (PD). At least 18 genetic loci and 13 disease-related genes for parkinsonism have been identified. The S100 calcium-binding beta (S100B), which is expressed and secreted by astrocytes, has been found to be associated with PD. To evaluate whether the S100B variants are related to PD in Chinese Han population, we conducted genetic examination of the S100B gene in 502 PD patients from Mainland China. We did identify two known variants c.279+4T>C (rs187503470) and c.99C>G (p.Leu33Leu, rs1051169) in our patients. Neither of these two variants is predicted to change amino acid or splice site, indicating that they are not pathogenic mutations. Our results suggest that mutations in the coding region or intron/exon boundaries of the S100B gene play little or no role in the development of PD in Chinese population.

Chronic fluoxetine treatment changes S100B expression during postnatal rat brain development

BACKGROUND

Fluoxetine, a selective serotonin reuptake inhibitor, is approved for treatment of childhood depression. In rats, fluoxetine influences neuronal development, but it is unclear whether it also influences glia development. S100B is a glia-derived calcium-binding protein, which may influence the development of serotonergic fibers and, vice versa, serotonin may influence the expression of S100B.

OBJECTIVES

The purpose of this study was to investigate whether fluoxetine treatment influences the expression of S100B during postnatal development, and whether potential changes are regionally dependent upon the time frame of drug administration.

METHODS

S100B gene expression and S100B protein expression in three different brain regions (frontal cortex, hippocampus, and striatum) were studied by real-time polymerase chain reaction (PCR) and immunohistochemistry, respectively. First, a short-term effect, 24 hours after a 14 day fluoxetine treatment (5 mg/kg/bw s.c.) of rats either from postnatal day (PD) 1 to 15, 21 to 35, or 50 to 64, was investigated. Then, the same treatment was used to analyze S100B gene and protein levels at PD 90 (long-term effect).

RESULTS

At PD 90, a significant increase of gene and protein expression was observed in all regions if rats were treated during PDs 21-35, whereas treatment during other periods had no long-term effects. A short-term effect 24 hours after fluoxetine treatment was found for almost all development stages and regions, demonstrated by a significant increase of S100B.

CONCLUSIONS

These results support recent research indicating a highly drug-sensitive period (i.e., periadolescence) of rat brain development. Therefore, further clinical studies should be performed to clarify whether such a sensitive period also exists in children.

Neuroprotein dynamics in the cerebrospinal fluid: intraindividual concomitant ventricular and lumbar measurements

OBJECTIVE

The measurement of neuromarker/neuroproteins in the cerebrospinal fluid (CSF) is gaining increased popularity. However, insufficient information is available on the rostrocaudal distribution of neuroproteins in the CSF to guarantee an appropriate interpretation of ventricular versus lumbar concentrations.

METHODS

In 10 patients treated with both an external ventricular and a lumbar CSF drain, we collected concomitant CSF samples. We measured CSF concentrations of the glial S100B protein, the neuron-specific enolase (Cobas e411®; Roche Diagnostics), the leptomeningeal β-trace protein (BN Pro Spec®; Dade Behring/Siemens), and the blood-derived albumin (Immage; Beckman Coulter). Statistical analysis was performed with a paired Wilcoxon signed ranks test.

RESULTS

In patients with a free CSF circulation without any recent neurosurgical procedure, S100B and neuron-specific enolase concentrations did not differ between the ventricular and lumbar CSF while β-trace and albumin levels were significantly higher in the lumbar than in the ventricular CSF (p=0.008 and p=0.005). Following posterior fossa tumor surgery, all proteins accumulate in the lumbar CSF.

CONCLUSION

For brain-derived proteins, we could not confirm a rostrocaudal CSF gradient while lepto-meningeal and blood-derived proteins accumulate in the lumbar CSF. We conclude that for the interpretation of protein CSF concentrations, the source of the sample is of crucial importance.

ONO-2506 inhibits spike-wave discharges in a genetic animal model without affecting traditional convulsive tests via gliotransmission regulation

BACKGROUND AND PURPOSE

Anticonvulsants have been developed according to the traditional neurotransmission imbalance hypothesis. However, the anticonvulsive pharmacotherapy currently available remains unsatisfactory. To develop new antiepileptic drugs with novel antiepileptic mechanisms, we have tested the antiepileptic actions of ONO-2506, a glial modulating agent, and its effects on tripartite synaptic transmission.

EXPERIMENTAL APPROACH

Dose-dependent effects of ONO-2506 on maximal-electroshock seizure (MES), pentylenetetrazol-induced seizure (PTZ) and epileptic discharge were determined in a genetic model of absence epilepsy in mice (Cacna1a(tm2Nobs/tm2Nobs) strain). Antiepileptic mechanisms of ONO-2506 were analysed by examining the interaction between ONO-2506 and transmission-modulating toxins (tetanus toxin, fluorocitrate, tetrodotoxin) on release of l-glutamate, d-serine, GABA and kynurenic acid in the medial-prefrontal cortex (mPFC) of freely moving rats using microdialysis and primary cultured rat astrocytes.

KEY RESULTS

ONO-2506 inhibited spontaneous epileptic discharges in Cacna1a(tm2Nobs/tm2Nobs) mice without affecting MES or PTZ. Given systemically, ONO-2506 increased basal release of GABA and kynurenic acid in the mPFC through activation of both neuronal and glial exocytosis, but inhibited depolarization-induced releases of all transmitters. ONO-2506 increased basal glial release of kynurenic acid without affecting those of l-glutamate, d-serine or GABA. However, ONO-2506 inhibited AMPA-induced releases of l-glutamate, d-serine, GABA and kynurenic acid.

CONCLUSIONS AND IMPLICATIONS

ONO-2506 did not affect traditional convulsive tests but markedly inhibited epileptic phenomena in the genetic epilepsy mouse model. ONO-2506 enhanced release of inhibitory neuro- and gliotransmitters during the resting stage and inhibited tripartite transmission during the hyperactive stage. The results suggest that ONO-2506 is a novel potential glial-targeting antiepileptic drug.

LINKED ARTICLE

This article is commented on by Onat, pp. 1086-1087 of this issue. To view this commentary visit http://dx.doi.org/10.1111/bph.12050.

Assessment of serum S100B and neuron specific enolase levels to evaluate the neurotoxıc effects of organıc solvent exposure

OBJECTIVES

Long-term organic solvent exposure may cause toxic effects in central nervous system . Trichloroethylene (TCE) is known to be one of the neurotoxic chlorinated organic solvents. Trichloroacetic acid (TCA) is an oxidative pathway metabolite of TCE. S100B, a calcium-binding protein in glial cells, and neuron specific enolase (NSE) in neuron cytoplasma are protein markers of astrocyte and neuron damage, respectively.

MATERIALS AND METHODS

Clinical and laboratory assesments were performed in 25 participants with organic solvent exposure history. Control group included 25 healthy age and sex-matched individuals. Measurements of serum S100B and NSE were performed using Roche Cobas E 601 compatible kits and elechtrochemiluminescence immunoassay. The levels of TCA in urine were measured by the headspace GC technique, after methyl esterification by methanol.

RESULTS

Median value of urine TCA in solvent-exposed group was 12.30 mg/L with 10.20 mg/L and 35.00 mg/L minimum and maximum values, respectively. The difference between serum S100B levels of solvent-exposed group (0.064 μg/L) and control group (0.049 μg/L) was statistically significant (p < 0.05). Serum NSE levels of control group (15.61 ng/ml) were higher than solvent-exposed group (13.90 ng/ml) but difference was not statistically significant (p > 0.05).

CONCLUSIONS

Serum S100B levels were found to be higher in solvent-exposed group when compared with control group. NSE levels were comparable between two groups. Increased Serum S100B levels in organic solvent exposure may indicate a preventive response to neuronal damage caused by reactive oxygen species (ROS) produced through oxidative metabolic pathways of organic solvents.

Brain-derived protein concentrations in the cerebrospinal fluid: contribution of trauma resulting from ventricular drain insertion

In recent years, the measurement of biomarkers following neurotrauma assisted in improving outcome prediction and guiding therapy. The use of neuroproteins as diagnostic parameters requires a detailed knowledge of their dynamics in biological fluids for an appropriate interpretation. S100B is the most widely studied neuromarker, and its concentration in serum and cerebrospinal fluid (CSF) reflects the extent of brain damage. Neuron-specific enolase (NSE) is considered reflecting neuronal damage, while Beta-Trace is a lepto-meningeal protein used to diagnose CSF leakage. In five patients treated with an external ventricular drain (EVD) because of aneurysmal subarachnoid hemorrhage (SAH, n=3) or postinfectious hydrocephalus (n=2), an EVD exchange was performed 8 to 12 days after initial insertion. S100B and NSE were measured with the Cobas e411(®) electrochemiluminescence assay (Roche Diagnostics, Mannheim, Germany) and Beta-Trace with the BN Pro Spec(®) nephelometer (Dade Behring/Siemens, Germany) 1 h before EVD exchange, upon the insertion of the new drain, and 1, 3, 6, 12, 18, 24 and 48 h after EVD exchange. Before EVD exchange, S100B CSF concentrations were within the normal range in all patients (1.48 ± 0.37 μg/L), while NSE CSF concentrations were normal in four of five patients (6.51 ± 2.98 μg/L). Following EVD exchange, S100B and NSE CSF levels peaked significantly at 3 h after insertion of the new drain (S100B 39.02 ± 9.17 μg/L; NSE 54.80 ± 43.34 μg/L). S100B serum levels were slightly increased 6 to 24 h after EVD exchange. Beta-Trace concentrations in the CSF were not altered by EVD insertion. Our data demonstrate that EVD insertion results in a distinct increase of S100B and NSE concentrations in the CSF. Thus, the tampering of brain-derived protein concentrations in the CSF by diagnostic or therapeutic procedures has to be considered in the interpretation of neuromarker levels.

CD166/ALCAM mediates proinflammatory effects of S100B in delayed type hypersensitivity

Promiscuity of pattern recognition receptors, such as receptor for advanced glycation end products (RAGE), allows for a complex regulatory network controlling inflammation. Scavenging of RAGE ligands by soluble RAGE treatment is effective in reducing delayed-type hypersensitivity (DTH), even in RAGE(-/-) mice by 50% (p < 0.001). This has led to the hypothesis that molecules scavenged by soluble RAGE bind to receptors other than RAGE. This study identifies CD166/ALCAM (ALCAM) as a close structural and functional homolog of RAGE, and it shows that binding of S100B to CD166/ALCAM induces dose- and time-dependent expression of members of the NF-κB family in wild type (WT) and RAGE(-/-) mouse endothelial cells. Blocking CD166/ALCAM expression using small interfering RNA completely inhibited S100B-induced NF-κB activation in RAGE(-/-), but not in WT cells. The in vivo significance of these observations was demonstrated by attenuation of DTH in WT and RAGE(-/-) animals pretreated with CD166/ALCAM small interfering RNA by 50% and 40%, respectively (p < 0.001). Experiments in ALCAM(-/-) animals displayed an only slight reduction of 16% in DTH, explained by compensatory reciprocal upregulation of RAGE in animals devoid of CD166/ALCAM, and vice versa. Consistently, ALCAM(-/-) mice, but not WT mice treated with RAGE small interfering RNA show a 35% reduction in DTH, and ALCAM(-/-) RAGE(-/-) double-knockout mice show a 27% reduction in DTH reaction. Thus, S100B is a proinflammatory cytokine bridging RAGE and CD166/ALCAM downstream effector mechanisms, both being compensatory upregulated after genetic deletion of its counterpart.

S100B promotes glioma growth through chemoattraction of myeloid-derived macrophages

PURPOSE

S100B is member of a multigenic family of Ca(2+)-binding proteins, which is overexpressed by gliomas. Recently, we showed that low concentrations of S100B attenuated microglia activation through the induction of Stat3. We hypothesized that overexpression of S100B in gliomas could promote tumor growth by modulating the activity of tumor-associated macrophages (TAM).

EXPERIMENTAL DESIGN

We stably transfected GL261 glioma cell lines with constructs that overexpressed (S100B(high)) or underexpressed (S100B(low)) S100B and compared their growth characteristics to intracranial wild-type (S100B(wt)) tumors.

RESULTS

Downregulation of S100B in gliomas had no impact on cell division in vitro but abrogated tumor growth in vivo. Interestingly, compared to S100B(low) tumors, S100B(wt) and S100B(high) intracranial gliomas exhibited higher infiltration of TAMs, stronger inflammatory cytokine expression, and increased vascularity. To identify the potential mechanisms involved, the expression of the S100B receptor, receptor for advanced glycation end products (RAGE), was evaluated in gliomas. Although S100B expression induced RAGE in vivo, RAGE ablation in mice did not significantly inhibit TAM infiltration into gliomas, suggesting that other pathways were involved in this process. To evaluate other mechanisms responsible for TAM chemoattraction, we then examined chemokine pathways and found that C-C motif ligand 2 (CCL2) was upregulated in S100B(high) tumors. Furthermore, analysis of The Cancer Genome Atlas's glioma data bank showed a positive correlation between S100B and CCL2 expression in human proneural and neural glioma subtypes, supporting our finding.

CONCLUSIONS

These observations suggest that S100B promotes glioma growth by TAM chemoattraction through upregulation of CCL2 and introduces the potential utility of S100B inhibitors for glioma therapy.

proNGF inhibits neurogenesis and induces glial activation in adult mouse dentate gyrus

Recent studies have shown that the precursor of nerve growth factor (proNGF) is highly elevated in aging brains and in the brains of patients with Alzheimer's Disease. proNGF accumulates in hippocampus which is an important neurogenic region related to learning and memory. However, it remains unclear whether proNGF has an influence on hippocampal neurogenesis. In this study, we demonstrated that the high-affinity receptor of proNGF, p75 neurotrophic factor (p75NTR), was expressed both on cells undergoing mitosis and postmitotic mature cells in mouse hippocampus. proNGF infusion into adult mouse hippocampus significantly reduced the density of BrdU-incorporating cells and the density of BrdU/Doublecortin double positive cells in the subgranular zone of hippocampus, indicating an inhibitory effect of proNGF on hippocampal neurogenesis. proNGF infusion also induced prominent cell apoptosis and activated residential astrocyte and microglia, which might further impair the hippocampal neurogenesis. These results implied that proNGF played a pivotal role in regulating the hippocampal neurogenesis and might account for the memory deficit and cognitive impairment.

Application of blood-based biomarkers in human mild traumatic brain injury

Traumatic Brain Injury (TBI) is a global health concern. The majority of TBI's are mild, yet our ability to diagnose and treat mild traumatic brain injury (mTBI) is lacking. This deficiency results from a variety of issues including the difficulty in interpreting ambiguous clinically presented symptoms, and ineffective imaging techniques. Thus, researchers have begun to explore cellular and molecular based approaches to improve both diagnosis and prognosis. This has been met with a variety of challenges, including difficulty in relating biological markers to current clinical symptoms, and overcoming our lack of fundamental understanding of the pathophysiology of mTBI. However, recent adoption of high throughput technologies and a change in focus from the identification of single to multiple markers has given just optimism to mTBI research. The purpose of this review is to highlight a number of current experimental peripheral blood biomarkers of mTBI, as well as comment on the issues surrounding their clinical application and utility.

Does Systemic Inflammation Play a Role in Pediatric Psychosis?

CONTEXT

Human and animal studies have suggested an underlying inflammatory mechanism for a variety of neuropsychiatric disorders, including schizophrenia. To date, most available reports focused on adult patients.

OBJECTIVE

We wished to test the hypothesis that the first psychotic episode in youth is associated with inflammation.

PATIENTS

We studied patients admitted to a pediatric inpatient psychiatric unit. Patients (n=80) had new-onset psychosis diagnosed using DSM-IV TR criteria for Psychosis NOS, Schizophreniform Disorder or Schizoaffective Disorder. Patients were matched for age, race and gender with inpatient controls without psychosis within the same unit (n=66). We also compared these values to normal pediatric hematologic values. To study the role of inflammation in youth with psychosis, we collected serum samples of 28 children presenting with first-episode psychosis and compared their serum cytokine and S100B levels to eight healthy controls.

MAIN OUTCOME MEASURES

In this study, we measured serum markers of systemic inflammation.

RESULTS

Leukocyte counts revealed a statistically significant increase in absolute monocytes compared to patients without psychosis (0.61 ± 0.282 k/ml vs. 0.496 ± 0.14 k/ml; p<0.01) and lymphocytes (2.51 ± 0.84 k/ml vs. 2.24 ± 0.72 k/ml; p<0.05) in patients with psychosis. All other hematologic values were similar between the groups. In addition, psychosis was characterized by increased serum levels of S100B, a peripheral marker of blood-brain barrier (BBB) damage. Several inflammatory mediators (e.g., TNF-α, IL-1β, IL-6, IL-5, IL-10, and IFN-γ) were elevated in children with psychosis.

CONCLUSIONS

These results strongly support a link between systemic inflammation, blood-brain barrier disruption and first-episode psychosis in pediatric patients.

Quantitative appraisal of ventricular cerebrospinal fluid biomarkers in neuropathologically diagnosed Parkinson's disease cases lacking Alzheimer's disease pathology

Identifying biomarkers that distinguish Parkinson’s disease (PD) from normal control (NC) individuals has the potential to increase diagnostic sensitivity for the detection of early-stage PD. A previous proteomic study identified potential biomarkers in postmortem ventricular cerebrospinal fluid (V-CSF) from neuropathologically diagnosed PD subjects lacking Alzheimer’s disease (AD) neuropathology. In the present study, we assessed these biomarkers as well as p-tau¹⁸¹, Aβ42, and S100B by ELISA in PD (n = 43) and NC (n = 49) cases. The p-tau¹⁸¹/Aβ42 ratio and ApoA-1 showed statistically significant differences between groups. Multiple regression analysis demonstrated that p-tau¹⁸¹/Aβ42 had a significant odds ratio: OR = 1.42 (95% confidence interval [CI], 1.12–1.84), P = 0.006. Among the molecules investigated, intriguing correlations were observed that require further investigation. Our results suggest coexistent AD CSF biomarkers within the PD group notwithstanding that it was selected to minimize AD neuropathological lesions.

Serum S100B protein: a useful marker in obstructive sleep apnea syndrome

BACKGROUND AND PURPOSE

We aimed to underline the importance of serum S100B protein as a useful biochemical marker in patients with obstructive sleep apnea syndrome (OSAS).

MATERIAL AND METHODS

Forty-three newly diagnosed patients with OSAS (median apnea-hypopnea index [AHI, events/ hour]: 37.5 [range 11.3-137]) and 25 subjects with AHI < 5 (median AHI: 4.4 [range 0.7-4.8]) were included in the study. Serum S100B protein level was tested in serum samples taken after polysomnography in both groups and the difference between OSAS patients and the control group regarding that level was assessed. In addition, the association of S100B protein serum level with age, body mass index, AHI, mean O2 saturation percentage during sleep, minimum O2 saturation value (%) at the end of the apneas, and the time spent at an O2 saturation less than 90% were analyzed in the OSAS patient group.

RESULTS

Median serum S100B protein level was 133.7 pg/ mL (range 20.97-230.70 pg/mL) in patients with OSAS and 16.1 pg/mL (range 10.1-22.9 pg/mL) in the control group (p < 0.005). Serum S100B protein level did not correlate with any studied variable (p > 0.05 for each correlation coefficient).

CONCLUSIONS

Serum S100B protein level is increased in patients with OSAS and may be a useful biochemical marker in those patients.

The role of serum cholinesterase activity and S100B protein in the evaluation of organophosphate poisoning

The aim of this study was to investigate the role of serum cholinesterase (SChE) activity and S100B protein in the evaluation of patients with acute organophosphate (OP) poisoning. Patients with acute OP poisoning admitted to the emergency department were included in this cross-sectional study. Twenty healthy volunteers served as controls. The SChE activity and serum S100B were determined on admission. Patients were divided into two groups (low severity and high severity). Thirty-six patients diagnosed with acute OP poisoning were enrolled. Serum S100B concentrations were higher in patients than in the control group ( p < 0.05). In the high-severity group, the SChE levels were lower and the S100Bs levels were higher than in the low-severity group. The SChE level was not different between survivors and nonsurvivors. S100B levels were higher in nonsurvivors than in survivors. According to receiver–operating characteristic curve analysis, the optimal cutoff value of serum S100B level to predict mortality was 236.5 pg/mL, with 71.4% sensitivity and 89.7% specificity. Our data suggest that initial SChE level is related to the clinical severity but not with mortality. S100B may be a useful marker in the assessment of clinical severity and prediction of mortality in acute OP poisoning.

Astrocyte plasticity revealed by adaptations to severe proteotoxic stress

Neurodegeneration is characterized by an accumulation of misfolded proteins in neurons. It is less well appreciated that glia often also accumulate misfolded proteins. However, glia are highly plastic and may adapt to stress readily. Endogenous adaptations to stress can be measured by challenging stressed cells with a second hit and then measuring viability. For example, subtoxic stress can elicit preconditioning or tolerance against second hits. However, it is not known if severe stress that kills half the population can elicit endogenous adaptations in the remaining survivors. Glia, with their resilient nature, offer an ideal model in which to test this new hypothesis. The present study is the first demonstration that astrocytes surviving one LC50 hit of the proteasome inhibitor MG132 were protected against a second MG132 hit. ATP loss in response to the second hit was also prevented. MG132 caused compensatory rises in stress-sensitive heat shock proteins. However, stressed astrocytes exhibited an even greater rise in ubiquitin-conjugated proteins upon the second hit, illustrating the severity of the proteotoxicity and verifying the continued impact of MG132. Despite this stress, MG132-pretreated astrocytes were completely prevented from losing glutathione with the second hit. Furthermore, inhibiting glutathione synthesis rendered astrocytes sensitive to the second hit, unmasking the cumulative impact of two hits by removal of an endogenous adaptation. These findings suggest that stressed astrocytes become progressively harder to kill by virtue of antioxidant defenses. Such plasticity may permit astrocytes under severe stress to better support neurons and help explain the protracted nature of neurodegeneration.

S100B is increased in Parkinson's disease and ablation protects against MPTP-induced toxicity through the RAGE and TNF-α pathway

Parkinson’s disease is a neurodegenerative disorder that can, at least partly, be mimicked by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. S100B is a calcium-binding protein expressed in, and secreted by, astrocytes. There is increasing evidence that S100B acts as a cytokine or damage-associated molecular pattern protein not only in inflammatory but also in neurodegenerative diseases. In this study, we show that S100B protein levels were higher in post-mortem substantia nigra of patients with Parkinson’s disease compared with control tissue, and cerebrospinal fluid S100B levels were higher in a large cohort of patients with Parkinson’s disease compared with controls. Correspondingly, mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine showed upregulated S100B messenger RNA and protein levels. In turn, ablation of S100B resulted in neuroprotection, reduced microgliosis and reduced expression of both the receptor for advanced glycation endproducts and tumour necrosis factor-α. Our results demonstrate a role of S100B in the pathophysiology of Parkinson’s disease. Targeting S100B may emerge as a potential treatment strategy in this disorder.

S100B and schizophrenia

The research for peripheral biological markers of schizophrenia, although abundant, has been unfruitful. In the last 2 decades, the S100B protein has made its own room in this area of research. S100B is a calcium-binding protein that has been proposed as a marker of astrocyte activation and brain dysfunction. Research results on S100B concentrations and schizophrenia clinical diagnosis are very consistent; patients with schizophrenia have higher S100B concentrations than healthy controls. The results regarding schizophrenia subtypes and clinical characteristics are not as conclusive. Age of patients, body mass index, illness duration and age at onset have been found to show no correlation, a positive correlation or a negative correlation with S100B levels. With respect to psychopathology, S100B data are inconclusive. Positive, negative and absence of correlation between S100B concentrations and positive and negative psychopathology have been reported. Methodological biases, such as day/night and seasonal variations, the use of anticoagulants to treat biological samples, the type of analytical technique to measure S100B and the different psychopathological scales to measure schizophrenia symptoms, are some of the factors that should be taken into account when researching into this area in order to reduce the variability of the reported results. The clinical implications of S100B changes in schizophrenia remain to be elucidated.

Clinical use of the calcium-binding S100B protein

S100B is a calcium-binding protein most abundant in neuronal tissue. It is expressed in glia cells and Schwann cells and exerts both intra- and extracellular effects. Depending on the concentration, secreted S100B exerts either trophic or toxic effects. Its functions have been extensively studied but are still not fully understood. It can be measured in cerebrospinal fluid and blood, and increased S100B level in blood can be seen after, e.g., traumatic brain injury, certain neurodegenerative disorders and malignant melanoma. This chapter provides a short background of protein S100B, commercially available methods of analysis, and its clinical use.

S100β Levels in CSF of Nonambulatory Dogs with Intervertebral Disk Disease Treated with Electroacupuncture

The aim of the study was to investigate S100β levels in the cerebrospinal fluid of nonambulatory dogs with intervertebral disk disease treated with electroacupuncture: 10 dogs with thoracolumbar disk extrusion graded 3 to 5 (EA group) and 7 dogs without neurologic dysfunction (control group). All dogs regained ambulation. S100β was detected by Western blot analysis where EA group dogs were evaluated at two time points (M1 = before EA and M2 = when the dogs return ambulation) and at one time point from control group. In EA group dogs M1-S100β levels were significantly higher than in control group. EA group dogs were divided into subgroups A (n = 7-early motor recovery; 6.7 ± 7.8 days) and B (n = 3-late motor recovery; 76 ± 17.0 days). M1-S100β levels were similar between subgroups A and B. However, M2-S100β levels were significantly higher in subgroup B than in subgroup A. An elevated S100β levels were observed in dogs with late motor recovery. S100β may be associated with neuroplasticity following spinal cord injuries with intervertebral disk extrusion. Further studies with larger numbers of subjects and control group with affected dogs are necessary to investigate the relationship between neurotrophic factors and electroacupuncture stimulation.

Resveratrol prevents ammonia toxicity in astroglial cells

Ammonia is implicated as a neurotoxin in brain metabolic disorders associated with hyperammonemia. Acute ammonia toxicity can be mediated by an excitotoxic mechanism, oxidative stress and nitric oxide (NO) production. Astrocytes interact with neurons, providing metabolic support and protecting against oxidative stress and excitotoxicity. Astrocytes also convert excess ammonia and glutamate into glutamine via glutamine synthetase (GS). Resveratrol, a polyphenol found in grapes and red wines, exhibits antioxidant and anti-inflammatory properties and modulates glial functions, such as glutamate metabolism. We investigated the effect of resveratrol on the production of reactive oxygen species (ROS), GS activity, S100B secretion, TNF-α, IL-1β and IL-6 levels in astroglial cells exposed to ammonia. Ammonia induced oxidative stress, decreased GS activity and increased cytokines release, probably by a mechanism dependent on protein kinase A (PKA) and extracellular signal-regulated kinase (ERK) pathways. Resveratrol prevented ammonia toxicity by modulating oxidative stress, glial and inflammatory responses. The ERK and nuclear factor-κB (NF-κB) are involved in the protective effect of resveratrol on cytokines proinflammatory release. In contrast, other antioxidants (e.g., ascorbic acid and trolox) were not effective against hyperammonemia. Thus, resveratrol could be used to protect against ammonia-induced neurotoxicity.

Os possíveis papéis da S100B na esquizofrenia

CONTEXTO: Evidências científicas do aumento da concentração da proteína S100B no sangue de pacientes esquizofrênicos são muito consistentes. No passado essa informação era principalmente considerada como reflexo da disfunção astroglial ou da barreira hematoencefálica. MÉTODOS: Pesquisa de publicações no PubMed até o dia 15 de junho de 2011 visando estabelecer potenciais ligações entre a proteína S100B e as hipóteses correntes da esquizofrenia. RESULTADOS: A S100B está potencialmente associada com as hipóteses dopaminérgica e glutamatérgica. O aumento da expressão de S100B tem sido detectado em astrócitos corticais em casos de esquizofrenia paranoide, enquanto se observa uma redução da expressão em oligodendrócitos na esquizofrenia residual, dando suporte à hipótese glial. Recentemente, a hipótese da neuroinflamação da esquizofrenia tem recebido atenção crescente. Nesse sentido, a S100B pode funcionar como uma citocina secretada por células gliais, linfócitos CD8+ e células NK, levando à ativação de monócitos e microglia. Além disso, a S100B apresenta propriedades do tipo adipocina e pode estar desregulada na esquizofrenia, devido a distúrbios da sinalização de insulina, levando ao aumento da liberação de S100B e ácidos graxos do tecido adiposo. CONCLUSÃO: A expressão de S100B em diferentes tipos celulares está envolvida em muitos processos regulatórios. Atualmente, não pode ser respondido qual mecanismo relacionado à esquizofrenia é o mais importante.