The ischemic rat heart releases S100B

S100B Serum Levels in Chronic Heart Failure Patients: A Multifaceted Biomarker Linking Cardiac and Cognitive Dysfunction

S100 calcium-binding protein B (S100B) is a protein primarily known as a biomarker for central nervous system (CNS) injuries, reflecting blood-brain barrier (BBB) permeability and dysfunction. Recently, S100B has also been implicated in cardiovascular diseases, including heart failure (HF). Thus, we investigated serum levels of S100B in 146 chronic HF patients from the Cognition.Matters-HF study and their association with cardiac and cognitive dysfunction. The median S100B level was 33 pg/mL (IQR: 22-47 pg/mL). Higher S100B levels were linked to longer HF duration (p = 0.014) and increased left atrial volume index (p = 0.041), but also with a higher prevalence of mild cognitive impairment (p = 0.023) and lower visual/verbal memory scores (p = 0.006). In a multivariable model, NT-proBNP levels independently predicted S100B (T-value = 2.27, p = 0.026). S100B did not impact mortality (univariable HR (95% CI) 1.00 (0.99-1.01); p = 0.517; multivariable HR (95% CI) 1.01 (1.00-1.03); p = 0.142), likely due to its reflection of acute injury rather than long-term outcomes and the mild HF phenotype in our cohort. These findings underscore S100B's value in comprehensive disease assessment, reflecting both cardiac dysfunction and potentially related BBB disruption.

Cerebrospinal Fluid and Serum Biomarker Insights in Aneurysmal Subarachnoid Haemorrhage: Navigating the Brain-Heart Interrelationship for Improved Patient Outcomes

The pathophysiological mechanisms underlying severe cardiac dysfunction after aneurysmal subarachnoid haemorrhage (aSAH) remain poorly understood. In the present study, we focused on two categories of contributing factors describing the brain-heart relationship. The first group includes brain-specific cerebrospinal fluid (CSF) and serum biomarkers, as well as cardiac-specific biomarkers. The secondary category encompasses parameters associated with cerebral autoregulation and the autonomic nervous system. A group of 15 aSAH patients were included in the analysis. Severe cardiac complications were diagnosed in seven (47%) of patients. In the whole population, a significant correlation was observed between CSF S100 calcium-binding protein B (S100B) and brain natriuretic peptide (BNP) (rS = 0.62; p = 0.040). Additionally, we identified a significant correlation between CSF neuron-specific enolase (NSE) with cardiac troponin I (rS = 0.57; p = 0.025) and BNP (rS = 0.66; p = 0.029), as well as between CSF tau protein and BNP (rS = 0.78; p = 0.039). Patients experiencing severe cardiac complications exhibited notably higher levels of serum tau protein at day 1 (0.21 ± 0.23 [ng/mL]) compared to those without severe cardiac complications (0.03 ± 0.04 [ng/mL]); p = 0.009. Impaired cerebral autoregulation was noted in patients both with and without severe cardiac complications. Elevated serum NSE at day 1 was related to impaired cerebral autoregulation (rS = 0.90; p = 0.037). On the first day, a substantial, reciprocal correlation between heart rate variability low-to-high frequency ratio (HRV LF/HF) and both GFAP (rS = -0.83; p = 0.004) and S100B (rS = -0.83; p = 0.004) was observed. Cardiac and brain-specific biomarkers hold the potential to assist clinicians in providing timely insights into cardiac complications, and therefore they contribute to the prognosis of outcomes.

S100 proteins in cardiovascular diseases

Cardiovascular diseases have become a serious threat to human health and life worldwide and have the highest fatality rate. Therefore, the prevention and treatment of cardiovascular diseases have become a focus for public health experts. The expression of S100 proteins is cell- and tissue-specific; they are implicated in cardiovascular, neurodegenerative, and inflammatory diseases and cancer. This review article discusses the progress in the research on the role of S100 protein family members in cardiovascular diseases. Understanding the mechanisms by which these proteins exert their biological function may provide novel concepts for preventing, treating, and predicting cardiovascular diseases.

Plasma Levels of Brain-Derived Neurotrophic Factor and S100B in Relation to Antidepressant Response to Ketamine

Background

Evidence demonstrates that brain-derived neurotrophic factor (BDNF) and S100 calcium-binding protein B (S100B) have a pivotal role in the pathogenesis of major depressive disorder (MDD) and they are proposed as predictors of antidepressant response. Ketamine produces rapid antidepressant effects in MDD and pre-clinical studies suggest the necessity of increased BDNF levels for the antidepressant action of ketamine. However, studies observing the change of blood BDNF levels after ketamine intervention are inconsistent and studies about the role of plasma S100B in ketamine administration in MDD patients are lacking.

Method

We evaluated mature BDNF (mBDNF), S100B levels in plasma and their associations with depression severity in 30 Selective Serotonin Reuptake Inhibitor (SSRI)-resistant MDD patients enrolled in a randomized controlled trial of ketamine compared (n = 20) to a placebo (n = 10) control (saline). Severity of depression was assessed using the Montgomery–Åsberg Depression Rating Scale (MADRS).

Results

Plasma mBDNF and S100B were not significantly changed after 1–2 days of single ketamine compared to placebo. Plasma mBDNF and S100B levels did not significantly differ in responders compared to non-responders of ketamine treatment. The change of plasma mBDNF levels was positively correlated with the improvement of MADRS score after 1–2 weeks of open-label ketamine treatment (rho = 0.495, p = 0.031), though this change did not survive correction for multiple comparisons.

Conclusion

These findings do not support the hypothesis that ketamine treatment increases BDNF plasma levels in MDD patients. No effect of ketamine treatment on S100B plasma levels was seen.

Secondary S100B Protein Increase Following Brain Arteriovenous Malformation Rupture is Associated with Cerebral Infarction

Early S100B protein serum elevation is associated with poor prognosis in patients with ruptured brain arteriovenous malformations (BAVM). The purpose of this study is to determine whether a secondary elevation of S100B is associated with early complications or poor outcome in this population. This is a retrospective study of patients admitted for BAVM rupture. A secondary increase of S100B was defined as an absolute increase by 0.1 μg/L within 30 days of admission. Fisher’s and unpaired t tests followed by multivariate analysis were performed to identify markers associated with this increase. Two hundred and twenty-one ruptures met inclusion criteria. Secondary S100B protein serum elevation was found in 17.1% of ruptures and was associated with secondary infarction (p < 0.001), vasospasm-related infarction (p < 0.001), intensive care (p = 0.009), and hospital length of stay (p = 0.005), but not with early rebleeding (p = 0.07) or in-hospital mortality (p = 0.99). Secondary infarction was the only independent predictor of secondary increase of S100B (OR 9.9; 95% CI (3–35); p < 0.001). Secondary elevation of S100B protein serum levels is associated with secondary infarction in ruptured brain arteriovenous malformations.

RAGE-dependent NF-kB inflammation processes in the capsule of frozen shoulders

BACKGROUND

The etiology of frozen shoulder (FS) remains uncertain. Advanced glycation end-products (AGEs) cause the cross-linking and stabilization of collagen and are increased in FS. The purpose of this study was to elucidate the pathogenesis of FS by evaluating the receptor of AGE (RAGE)-dependent pathways.

METHODS

Tissue samples of the coracohumeral ligament (CHL) and anterior inferior glenohumeral ligament (IGHL) were collected from 33 patients with FS, with severe stiffness, and 25 with rotator cuff tears (RCTs) as controls. Gene expression levels of RAGE, high-mobility group box 1 (HMGB1), Toll-like receptor 2 (TLR2), TLR4, nuclear factor-kappa B (NF-kB), and cytokines were evaluated using a quantitative real-time polymerase chain reaction. The immunoreactivities of carboxymethyllysine (CML), pentosidine, and RAGE were also evaluated. CML and pentosidine were further evaluated using high-performance liquid chromatography.

RESULTS

Gene expression levels of RAGE, HMGB1, TLR2, TLR4, and NF-kB were significantly greater in the CHLs and IGHLs from the FS group than in those from the RCT group. Immunoreactivities of RAGE and CML were stronger in the CHLs and IGHLs from the FS group than in those from the RCT group. Pentosidine was weakly immunostained in the CHLs and IGHLs from the FS group. CML using high-performance liquid chromatography was significantly greater in the CHLs and IGHLs from the FS group than in those from the RCT group.

CONCLUSIONS

AGEs and HMGB1 might play important roles in the pathogenesis of FS by binding to RAGE and activating NF-kB signaling pathways. Suppression of these pathways could be a treatment option for FS.

The effect of obstructive sleep apnea syndrome on serum S100B and NSE levels: a systematic review and meta-analysis of observational studies

Background

Obstructive sleep apnea syndrome (OSAS) is a common disorder that is accompanied by structural brain changes. This meta-analysis aimed to evaluate the effect of OSAS on the serum levels of astrocytic protein (S100B) and neuron-specific enolase (NSE) in observational studies.

Methods

A comprehensive search was performed in the PubMed/Medline, Web of Science, Scopus, ScienceDirect, and Cochrane Library databases to assess the serum level of S100B and/or NSE in patients with OSAS and/or controls. The quality of the study was evaluated by the Newcastle-Ottawa Scale (NOS). A random-effects model was performed using RevMan 5.3 with the mean difference (MD) and 95% confidence intervals (CIs).

Results

Out of 63 studies found in the mentioned databases and one identified by a manual search, nine studies were included and analyzed in this meta-analysis (three cross-sectional and six case-control studies). The analysis showed that the S100B [MD = 53.58 pg/ml, 95%CI: 1.81, 105.35; P = 0.04] and NSE levels [MD = 3.78 ng/ml, 95%CI: 2.07, 5.48; P < 0.0001] were significantly higher in patients than the controls. However, there were no significant differences between the S100B [MD = -28.00 pg/ml, 95%CI: − 79.48, 23.47; P = 0.29] and NSE levels [MD = 0.49 ng/ml, 95%CI: − 0.82, 1.80; P = 0.46].

Conclusions

This meta-analysis found elevated serum S100B and NSE levels in OSAS patients compared to the controls, which suggests that these markers may be used as peripheral indicators of brain damage in OSAS.

Endothelial RAGE exacerbates acute postischaemic cardiac inflammation

Advanced glycation end-products (AGEs) interact with their receptor RAGE, leading to an inflammatory state. We investigated the role of RAGE in postischaemic leukocyte adhesion after myocardial infarction and its effect on postischaemic myocardial function. Wildtype (WT), ICAM-1-/-, RAGE-/- or ICAM-1/RAGE-/- mice underwent 20 minutes (min) of LAD-occlusion followed by 15 min of reperfusion. We applied in vivo fluorescence microscopy visualising Rhodamine-6G labelled leukocytes. To differentiate between endothelial and leukocyte RAGE, we generated bone marrow chimeric mice. Invasive hemodynamic measurements were performed in mice undergoing 45 min of myocardial ischaemia (via LAD-occlusion) followed by 24 hours of reperfusion. Left-ventricular developed pressure (LVDP) was assessed by insertion of a millar-tip catheter into the left ventricle. In the acute model of myocardial ischaemia, leukocyte retention (WT 68 ± 4 cells/ hpf) was significantly reduced in ICAM-1-/- (40 ± 3 cells/hpf) and RAGE-/- mice (38 ± 4 cells/hpf). ICAM-1/RAGE-/- mice displayed an additive reduction of leukocyte retention (ICAM-1/RAGE-/- 15 ± 3 cells/ hpf). Ly-6G+ neutrophil were predominantly reduced in ICAM-1/RAGE-/- hearts (28%), whereas Ly-6C+ proinflammatory monocytes decreased to a lesser extent (55%). Interestingly, PMN recruitment was not affected in chimeric mice with RAGE deficiency in BM cells (WT mice reconstituted with ICAM-1/RAGE-/- BM: 55 ± 4 cells/hpf) while in mice with global RAGE deficiency (ICAM-1/RAGE-/- mice reconstituted with ICAM-1/RAGE-/- BM) leucocyte retention was significantly reduced (13 ± 1 cells/hpf), similar to non-transplanted ICAM/ RAGE-/- mice. Furthermore, postischaemic LVDP increased in ICAM-1/RAGE-/- animals (98 ± 4 mmHg vs 86 ± 4 mmHg in WT mice). In conclusion, combined deficiency of ICAM-1 and RAGE reduces leukocyte influx into infarcted myocardium and improves LV function during the acute phase after myocardial ischaemia and reperfusion. RAGE represents an additional pro-inflammatory endothelial mediator of ischaemia-reperfusion injury.

Correlation between Amitriptyline-Induced Cardiotoxic Effects and Cardiac S100b Protein in Isolated Rat Hearts

BACKGROUND

Amitriptyline is an important cause of mortality due to its cardiovascular toxicity.

AIMS

To investigate the changes in levels of cardiac S100b protein on amitriptyline-induced cardiotoxicity and also to examine the correlation between amitriptyline-induced cardiotoxic effects and cardiac S100b protein in an isolated rat heart model.

STUDY DESIGN

Animal experimentation, isolated heart model.

METHODS

After a stabilization period, isolated hearts were randomized to two groups (n=5 and n=7). In the control group, isolated hearts were subjected to an infusion of 5% dextrose for 60 minutes. In the amitriptyline group, 5.5×10^-5 M amitriptyline was infused for 60 minutes to achieve amitriptyline toxicity. After the infusion period, heart tissues were removed for histological examination.

RESULTS

In comparison to control treatment, amitriptyline infusion decreased left ventricular developed pressure (LVDP), dp/dtmax and heart rate (HR) and significantly prolonged QRS duration (p<0.05). The semiquantitative scores for S100b protein levels in amitriptyline-infused hearts were higher than in the control group (p<0.01). At the end of the experiment, in the amitriptyline-infused group, significant correlations were found between LVDP and S100b protein scores (r=-0.807, p=0.003) and between QRS duration and S100b protein scores (r=0.859, p=0.001).

CONCLUSION

Our results indicate that the S100b protein may be a helpful indicator or biomarker in studying the cardiotoxic effects of amitriptyline.

Current status of fluid biomarkers in mild traumatic brain injury

Mild traumatic brain injury (mTBI) affects millions of people annually and is difficult to diagnose. Mild injury is insensitive to conventional imaging techniques and diagnoses are often made using subjective criteria such as self-reported symptoms. Many people who sustain a mTBI develop persistent post-concussive symptoms. Athletes and military personnel are at great risk for repeat injury which can result in second impact syndrome or chronic traumatic encephalopathy. An objective and quantifiable measure, such as a serum biomarker, is needed to aid in mTBI diagnosis, prognosis, return to play/duty assessments, and would further elucidate mTBI pathophysiology. The majority of TBI biomarker research focuses on severe TBI with few studies specific to mild injury. Most studies use a hypothesis-driven approach, screening biofluids for markers known to be associated with TBI pathophysiology. This approach has yielded limited success in identifying markers that can be used clinically, additional candidate biomarkers are needed. Innovative and unbiased methods such as proteomics, microRNA arrays, urinary screens, autoantibody identification and phage display would complement more traditional approaches to aid in the discovery of novel mTBI biomarkers.

S100B Serum Levels Predict Treatment Response in Patients with Melancholic Depression

BACKGROUND

There is an ongoing search for biomarkers in psychiatry, for example, as diagnostic tools or predictors of treatment response. The neurotrophic factor S100 calcium binding protein B (S100B) has been discussed as a possible predictor of antidepressant response in patients with major depression, but also as a possible biomarker of an acute depressive state. The aim of the present study was to study the association of serum S100B levels with antidepressant treatment response and depression severity in melancholically depressed inpatients.

METHODS

After a wash-out period of 1 week, 40 inpatients with melancholic depression were treated with either venlafaxine or imipramine. S100B levels and Hamilton Depression Rating Scale (HAM-D) scores were assessed at baseline, after 7 weeks of treatment, and after 6 months.

RESULTS

Patients with high S100B levels at baseline showed a markedly better treatment response defined as relative reduction in HAM-D scores than those with low baseline S100B levels after 7 weeks (P=.002) and 6 months (P=.003). In linear regression models, S100B was a significant predictor for treatment response at both time points. It is of interest to note that nonresponders were detected with a predictive value of 85% and a false negative rate of 7.5%. S100B levels were not associated with depression severity and did not change with clinical improvement.

CONCLUSIONS

Low S100B levels predict nonresponse to venlafaxine and imipramine with high precision. Future studies have to show which treatments are effective in patients with low levels of S100B so that this biomarker will help to reduce patients' burden of nonresponding to frequently used antidepressants.

The importance of glia in dealing with stress

Glia are starting to be accepted as the equal of neurons. Their impact on intelligence, environmental enrichment, and cerebral dominance forms the basis for understanding the role of glia in stress. Along with neurons, astrocytes, microglia, NG2 cells, and oligodendrocytes all contribute. Glia can even be protective against drug abuse. Glial effects on depression, mood disorders and schizophrenia are reviewed.

Serum S100B level increases after running but not cycling exercise

The objective of this study was to investigate the effect of running versus cycling exercises upon serum S100B levels and typical markers of skeletal muscle damage such as creatine kinase (CK), aspartate aminotransferase (AST) and myoglobin (Mb). Although recent work demonstrates that S100B is highly expressed and exerts functional properties in skeletal muscle, there is no previous study that tries to establish a relationship between muscle damage and serum S100B levels after exercise. We conducted a cross-sectional study on 13 male triathletes. They completed 2 submaximal exercise protocols at anaerobic threshold intensity. Running was performed on a treadmill with no inclination (RUN) and cycling (CYC) using a cycle-simulator. Three blood samples were taken before (PRE), immediately after (POST) and 1 h after exercise for CK, AST, Mb and S100B assessments. We found a significant increase in serum S100B levels and muscle damage markers in RUN POST compared with RUN PRE. Comparing groups, POST S100B, CK, AST and Mb serum levels were higher in RUN than CYC. Only in RUN, the area under the curve (AUC) of serum S100B is positively correlated with AUC of CK and Mb. Therefore, immediately after an intense exercise such as running, but not cycling, serum levels of S100B protein increase in parallel with levels of CK, AST and Mb. Additionally, the positive correlation between S100B and CK and Mb points to S100B as an acute biomarker of muscle damage after running exercise.

Functions of S100 proteins

The S100 protein family consists of 24 members functionally distributed into three main subgroups: those that only exert intracellular regulatory effects, those with intracellular and extracellular functions and those which mainly exert extracellular regulatory effects. S100 proteins are only expressed in vertebrates and show cell-specific expression patterns. In some instances, a particular S100 protein can be induced in pathological circumstances in a cell type that does not express it in normal physiological conditions. Within cells, S100 proteins are involved in aspects of regulation of proliferation, differentiation, apoptosis, Ca2+ homeostasis, energy metabolism, inflammation and migration/invasion through interactions with a variety of target proteins including enzymes, cytoskeletal subunits, receptors, transcription factors and nucleic acids. Some S100 proteins are secreted or released and regulate cell functions in an autocrine and paracrine manner via activation of surface receptors (e.g. the receptor for advanced glycation end-products and toll-like receptor 4), G-protein-coupled receptors, scavenger receptors, or heparan sulfate proteoglycans and N-glycans. Extracellular S100A4 and S100B also interact with epidermal growth factor and basic fibroblast growth factor, respectively, thereby enhancing the activity of the corresponding receptors. Thus, extracellular S100 proteins exert regulatory activities on monocytes/macrophages/microglia, neutrophils, lymphocytes, mast cells, articular chondrocytes, endothelial and vascular smooth muscle cells, neurons, astrocytes, Schwann cells, epithelial cells, myoblasts and cardiomyocytes, thereby participating in innate and adaptive immune responses, cell migration and chemotaxis, tissue development and repair, and leukocyte and tumor cell invasion.

RAGE regulation and signaling in inflammation and beyond

RAGE is a key molecule in the onset and sustainment of the inflammatory response. New studies indicate that RAGE might represent a new link between the innate and adaptive immune system. RAGE belongs to the superfamily of Ig cell-surface receptors and is expressed on all types of leukocytes promoting activation, migration, or maturation of the different cells. RAGE expression is prominent on the activated endothelium, where it mediates leukocyte adhesion and transmigration. Moreover, proinflammatory molecules released from the inflamed or injured vascular system induce migration and proliferation of SMCs. RAGE binds a large number of different ligands and is therefore considered as a PRR, recognizing a structural motif rather than a specific ligand. In this review, we summarize the current knowledge about the signaling pathways activated in the different cell types and discuss a potential activation mechanism of RAGE, as well as putative options for therapeutic intervention.

S100B protein expression in the heart of deceased individuals by overdose: a new forensic marker?

OBJECTIVE

The evaluation of S100B protein expression in the human heart and its correlation with drug-related death.

METHOD

Left ventricular samples were collected from 74 serial forensic autopsies (15 overdose-related deaths; 59 non-overdose-related deaths) from 2007 to 2010. Tissue sections from each sample were immunostained for S100B protein by a commercial antibody.

RESULTS

The S100B protein was detected in the heart samples of all 15 cases of drug-related deaths; S100B immunoreactivity was mainly observed in the cytoplasm of cardiomyocytes and as globular deposits in the interstitial spaces. No reactivity or weak reactivity was found in the cardiomyocytes of the 59 subjects who died of other causes.

CONCLUSION

Our preliminary data show that the S100B protein accumulates in injured cardiomyocytes during drug-related sudden death. Given the near absence of S100B protein in the heart of subjects who died from causes other than drug overdose, S100B immunopositivity may be used as a new ancillary screening tool for the postmortem diagnosis of overdose-related cardiac death.

The S100B protein in biological fluids: more than a lifelong biomarker of brain distress

S100B is a calcium-binding protein concentrated in glial cells, although it has also been detected in definite extra-neural cell types. Its biological role is still debated. When secreted, S100B is believed to have paracrine/autocrine trophic effects at physiological concentrations, but toxic effects at higher concentrations. Elevated S100B levels in biological fluids (CSF, blood, urine, saliva, amniotic fluid) are thus regarded as a biomarker of pathological conditions, including perinatal brain distress, acute brain injury, brain tumors, neuroinflammatory/neurodegenerative disorders, psychiatric disorders. In the majority of these conditions, high S100B levels offer an indicator of cell damage when standard diagnostic procedures are still silent. The key question remains as to whether S100B is merely leaked from injured cells or is released in concomitance with both physiological and pathological conditions, participating at high concentrations in the events leading to cell injury. In this respect, S100B levels in biological fluids have been shown to increase in physiological conditions characterized by stressful physical and mental activity, suggesting that it may be physiologically regulated and raised during conditions of stress, with a putatively active role. This possibility makes this protein a candidate not only for a biomarker but also for a potential therapeutic target.

Is serum S100B protein a biomarker for amitriptyline-induced cardiovascular toxic effects?

The aim of this study was to assess the role of serum S100B protein as a biomarker for cardiovascular effects in an anesthetized rat model of amitriptyline toxicity. Adult male Wistar rats (n = 28) were randomized into four groups. While the control group received normal saline, the experimental groups received different doses of amitriptyline (0.625 or 0.94 or 1.25 mg/kg/min) infusion. Mean arterial pressure (MAP), heart rate (HR), electrocardiogram parameters, and serum S100B protein levels were recorded during the experiment. Linear Pearson's correlation coefficient was used to examine the association between cardiovascular parameters and serum levels of S100B protein. In the experimental groups, amitriptyline caused a significant decrease in MAP and HR (P < 0.001), a prolongation in QRS duration and QT intervals (P < 0.01), but it did not change PR intervals significantly. At the end of the experiment of the second group, a significant correlation was found between HR and serum S100B protein levels (r = -0.963, P = 0.037). At the end of the experiment of the third and fourth groups, a significant correlation between MAP, HR, all ECG parameters, and serum S100B protein levels was found. Serum S100B protein levels correlate well with amitriptyline-induced cardiovascular toxicity and can be used as a biomarker for predicting cardiovascular toxic effects of amitriptyline.

RAGE does not contribute to renal injury and damage upon ischemia/reperfusion-induced injury

The receptor for advanced glycation end products (RAGE) mediates a variety of inflammatory responses in renal diseases, but its role in renal ischemia/reperfusion (I/R) injury is unknown. We showed that during renal I/R, RAGE ligands HMGB1 and S100B are expressed. However, RAGE deficiency does not affect renal injury and function upon I/R-induced injury.

S100B-RAGE dependent VEGF secretion by cardiac myocytes induces myofibroblast proliferation

Post-infarct remodeling is associated with the upregulation of the receptor for advanced glycation end products (RAGE), the induction of its ligand the calcium binding protein S100B and the release of the potent endothelial-cell specific mitogen vascular endothelial growth factor (VEGF). To determine a possible functional interaction between S100B, RAGE and VEGF we stimulated rat neonatal cardiac myocyte cultures transfected with either RAGE or a dominant-negative cytoplasmic deletion mutant of RAGE with S100B for 48 h. Under baseline conditions, cardiac myocytes express low levels of RAGE and VEGF and secrete VEGF in the medium as measured by ELISA. In RAGE overexpressing myocytes, S100B (100 nM) resulted in increases in VEGF mRNA, VEGF protein, VEGF secretion, and activation of the transcription factor NF-κB. Pre-treatment of RAGE overexpressing myocytes with the NF-κB inhibitor caffeic acid phenethyl ester inhibited increases in VEGF mRNA, VEGF protein and VEGF in the medium by S100B. In myocytes expressing dominant-negative RAGE, S100B did not induce VEGF mRNA, VEGF protein, VEGF secretion or NF-κB activation. In culture, rat neonatal and adult cardiac fibroblasts undergo phenotypic transition to myofibroblasts. Treatment of neonatal and adult myofibroblasts with VEGF (10 ng/mL) induces VEGFR-2 (flk-1/KDR) tyrosine kinase phosphorylation, ERK1/2 phosphorylation and myofibroblast proliferation. Together these data demonstrate that secreted VEGF by cardiac myocytes in response to S100B via RAGE ligation induces myofibroblast proliferation potentially contributing to scar formation observed in infarcted myocardium. This article is part of a Special Issue entitled "Local Signaling in Myocytes".

Increased serum levels of S100B are related to the severity of cardiac dysfunction, renal insufficiency and major cardiac events in patients with chronic heart failure

OBJECTIVE

To investigate the correlations between S100B and the severity of cardiac dysfunction, renal insufficiency (RI) and prognosis in chronic heart failure (CHF).

METHOD

Serum levels of S100B, TNF-α, high sensitivity CRP and NT-proBNP were determined in CHF patients with (n=96) and without RI (n=146). Patients with RI only (n=62) and control subjects (n=64) served for comparison. Patients were followed up for one year.

RESULTS

S100B levels were higher in CHF patients with a further elevation in those with RI (P<0.01). Serum S100B levels correlated with left ventricular ejection fraction, left ventricular end-diastolic volume and NT-proBNP in CHF patients, and eGFR in patients with RI (all P<0.05). Increased S100B levels were associated with major cardiac events (MCE), and were independently associated with the presence of CHF (all P<0.05).

CONCLUSION

Increased serum S100B levels were associated with the severity of cardiac dysfunction, RI and an adverse prognosis in CHF patients. It represents an independent risk factor for CHF.

The significance of protein S-100B testing in cardiac arrest patients

Cardiac arrest often represents the first expression of an underlying cardiac disease. Despite advances in neurocritical care, the neurological assessment of cardiac arrest patients relies on clinical, instrumental and biochemical parameters. The clinical significance of S-100 calcium binding protein B (S-100B) has substantially increased throughout several areas of clinical neuroscience, but reliable evidences attest it can be used as a reliable and early predictor of poor physiological and cognitive neurological outcomes after cardiac arrest.

How does extracerebral trauma affect the clinical value of S100B measurements?

Background

Protein S100B has proven to be a useful biomarker for cerebral damage. The predictive ability of S100B may, however, be affected by extracerebral injuries. The aim of this study was to investigate serum levels of S100B in patients with either isolated head injury (IHI), multi trauma with head injury (MTHI), or no head injury (NHI). The primary aim was to assess if a significant difference in serum levels of S100B could be found between IHI and MTHI patients.

Methods

Patients (233) were primarily admitted to the trauma centre. Serum samples were drawn on admission and 6 h after trauma and then stored at −80°C until analysed. Variables included Abbreviated Injury Scale (AIS) for head trauma, Injury Severity Score (ISS) and 30-day survival.

Results

Two patients could not be classified. IHI occurred in 28, MTHI in 102 and NHI was found in 101. The median S100B concentrations on arrival were 0.47, 1.68 and 0.49 μg/l, respectively (p<0.0001). The corresponding values at 6 h were 0.14, 0.31 and 0.15 μg/l, respectively (p<0.0001). S100B was significantly higher in patients with MTHI than in patients with IHI at both time points (p values 0.0005 and 0.01). There was no significant difference in S100B between patients having IHI and patients with NHI (p=0.81 and p=0.67).

Conclusions

High serum levels of S100B were found early after trauma. The highest concentrations of S100B were found in patients with multi trauma. This suggests that S100B serum concentrations are significantly affected by extracerebral injuries.

TD-11 workshop report: characterization of monoclonal antibodies to S100 proteins

Fourteen monoclonal antibodies with specificity against native or recombinant antigens within the S100 family were investigated with regard to immunoreactivity. The specificities of the antibodies were studied using ELISA tests, Western blotting epitope mapping using competitive assays, and QCM technology. The mimotopes of antibodies against S100A4 were determined by random peptide phage display libraries. Antibody specificity was also tested by IHC and pair combinations evaluated for construction of immunoradiometric assays for S100B. Out of the 14 antibodies included in this report eight demonstrated specificity to S100B, namely MAbs 4E3, 4D2, S23, S53, 6G1, S21, S36, and 8B10. This reactivity could be classified into four different epitope groups using competing studies. Several of these MAbs did display minor reactivity to other S100 proteins when they were presented in denatured form. Only one of the antibodies, MAb 3B10, displayed preferential reactivity to S100A1; however, it also showed partial cross-reactivity with S100A10 and S100A13. Three antibodies, MAbs 20.1, 22.3, and S195, were specific for recombinant S100A4 in solution. Western blot revealed that MAb 20.1 and 22.3 recognized linear epitopes of S100A4, while MAb S195 reacted with a conformational dependent epitope. Surprisingly, MAb 14B3 did not demonstrate any reactivity to the panel of antigens used in this study.

S100A1: a multifaceted therapeutic target in cardiovascular disease

Cardiovascular disease is the leading cause of death worldwide, showing a dramatically growing prevalence. It is still associated with a poor clinical prognosis, indicating insufficient long-term treatment success of currently available therapeutic strategies. Investigations of the pathomechanisms underlying cardiovascular disorders uncovered the Ca(2+) binding protein S100A1 as a critical regulator of both cardiac performance and vascular biology. In cardiomyocytes, S100A1 was found to interact with both the sarcoplasmic reticulum ATPase (SERCA2a) and the ryanodine receptor 2 (RyR2), resulting in substantially improved Ca(2+) handling and contractile performance. Additionally, S100A1 has been described to target the cardiac sarcomere and mitochondria, leading to reduced pre-contractile passive tension as well as enhanced oxidative energy generation. In endothelial cells, molecular analyses revealed a stimulatory effect of S100A1 on endothelial NO production by increasing endothelial nitric oxide synthase activity. Emphasizing the pathophysiological relevance of S100A1, myocardial infarction in S100A1 knockout mice resulted in accelerated transition towards heart failure and excessive mortality in comparison with wild-type controls. Mice lacking S100A1 furthermore displayed significantly elevated blood pressure values with abrogated responsiveness to bradykinin. On the other hand, numerous studies in small and large animal heart failure models showed that S100A1 overexpression results in reversed maladaptive myocardial remodeling, long-term rescue of contractile performance, and superior survival in response to myocardial infarction, indicating the potential of S100A1-based therapeutic interventions. In summary, elaborate basic and translational research established S100A1 as a multifaceted therapeutic target in cardiovascular disease, providing a promising novel therapeutic strategy to future cardiologists.

S100B interaction with the receptor for advanced glycation end products (RAGE): a novel receptor-mediated mechanism for myocyte apoptosis postinfarction

RATIONALE

Post-myocardial infarction ventricular remodeling is associated with the expression of a variety of factors including S100B that can potentially modulate myocyte apoptosis.

OBJECTIVE

This study was undertaken to investigate the expression and function of S100B and its receptor, the receptor for advanced glycation end products (RAGE) in both postinfarction myocardium and in a rat neonatal myocyte culture model.

METHODS AND RESULTS

In a rat model of myocardial infarction following coronary artery ligation, we demonstrate in periinfarct myocytes, upregulation of RAGE, induction of S100B, and release into plasma with consequent myocyte apoptosis. Using a coimmunoprecipitation strategy, we demonstrate a direct interaction between S100B and RAGE. In rat neonatal cardiac myocyte cultures, S100B at concentrations > or = 50 nmol/L induced myocyte apoptosis, as evidenced by increased terminal DNA fragmentation, TUNEL, cytochrome c release from mitochondria to cytoplasm, phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and p53, increased expression and activity of proapoptotic caspase-3, and decreased expression of antiapoptotic Bcl-2. Transfection of a full-length cDNA of RAGE or a dominant-negative mutant of RAGE resulted in increased or attenuated S100B-induced myocyte apoptosis, respectively. Inhibition of ERK1/2 by U0126/PD-98059 or overexpression of a dominant negative p53 comparably inhibited S100B-induced myocyte apoptosis.

CONCLUSIONS

These results suggest that interaction of RAGE and its ligand S100B after myocardial infarction may play a role in myocyte apoptosis by activating ERK1/2 and p53 signaling. This receptor-mediated mechanism is uniquely amenable to therapeutic intervention.

S100A1 in cardiovascular health and disease: closing the gap between basic science and clinical therapy

Calcium (Ca(2+)) signaling plays a major role in a wide range of physiological functions including control and regulation of cardiac and skeletal muscle performance and vascular tone. As all Ca(2+) signals require proteins to relay intracellular Ca(2+) oscillations downstream to different signaling networks, a specific toolkit of Ca(2+)-sensor proteins involving members of the EF-hand S100 Ca(2+) binding protein superfamily maintains the integrity of the Ca(2+) signaling in a variety of cardiac and vascular cells, transmitting the message with great precision and in a temporally and spatially coordinated manner. Indeed, the possibility that S100 proteins might contribute to heart and vascular diseases was first suggested by the discovery of distinctive patterns of S100 expression in healthy and diseased hearts and vasculature from humans and animal heart failure (HF) models. Based on more elaborate genetic studies in mice and strategies to manipulate S100 protein expression in human cardiac, skeletal muscle and vascular cells, it is now apparent that the integrity of distinct S100 protein isoforms in striated muscle and vascular cells such as S100A1, S100A4, S100A6, S100A8/A9 or S100B is a basic requirement for normal cardiovascular and muscular development and function; loss of integrity would naturally lead to profound deregulation of the implicated Ca(2+) signaling systems with detrimental consequences to cardiac, skeletal muscle, and vascular function. The brief debate and discussion here are confined by design to the biological actions and pathophysiological relevance of the EF-hand Ca(2+)-sensor protein S100A1 in the heart, vasculature and skeletal muscle with a particular focus on current translational therapeutic strategies. By virtue of its ability to modulate the activity of numerous key effector proteins that are essentially involved in the control of Ca(2+) and NO homeostasis in cardiac, skeletal muscle and vascular cells, S100A1 has been proven to play a critical role both in cardiac performance, blood pressure regulation and skeletal muscle function. Given that deregulated S100A1 expression in cardiomyocytes and endothelial cells has recently been linked to heart failure and hypertension, it is arguably a molecular target of considerable clinical interest as S100A1 targeted therapies have already been successfully investigated in preclinical translational studies.

Blood-brain barrier integrity in a rat model of emergency preservation and resuscitation

Emergency Preservation and Resuscitation (EPR) represents a novel approach to treat exsanguination cardiac arrest (CA) victims, using an aortic flush to induce hypothermia during circulatory arrest, followed by delayed resuscitation with cardiopulmonary bypass (CPB). The status of the blood-brain barrier (BBB) integrity after prolonged hypothermic CA is unclear. The objective of this study was to assess BBB permeability in two EPR models in rats, associated with poor outcome. Rats subjected to traumatic brain injury (TBI) and naïve rats served as positive and negative controls, respectively.

HYPOTHESIS

The BBB will be disrupted after TBI, but intact after prolonged hypothermic CA.

METHODS

Four groups were studied: (1) EPR-IC (ice cold)-75 min CA at 15 degrees C; (2) EPR-RT (room temperature)-20 min CA at 28 degrees C; (3) TBI; (4) sham. Rats in EPR groups were subjected to rapid hemorrhage, followed by CA. Rats in the TBI group had a controlled cortical impact to the left hemisphere. Naïves were subjected to the same anesthesia and surgery. 1h after insult, rats were injected with Evans Blue (EB), a marker of BBB permeability for albumin. Rats were sacrificed after 5h and EB absorbance was quantified in brain samples.

RESULTS

TBI produced an approximately 10-fold increase in EB absorbance in the left (injured) hemisphere vs. left hemisphere for all other groups (p=0.001). In contrast, EB absorbance in either EPR group did not differ from sham.

CONCLUSION

BBB integrity to albumin is not disrupted early after resuscitation from prolonged CA treated with EPR. Neuroprotective adjuncts to hypothermia in this setting should focus on agents that penetrate the BBB. These findings also have implications for deep hypothermic circulatory arrest.

S100B's double life: intracellular regulator and extracellular signal

The Ca2+-binding protein of the EF-hand type, S100B, exerts both intracellular and extracellular functions. Recent studies have provided more detailed information concerning the mechanism(s) of action of S100B as an intracellular regulator and an extracellular signal. Indeed, intracellular S100B acts as a stimulator of cell proliferation and migration and an inhibitor of apoptosis and differentiation, which might have important implications during brain, cartilage and skeletal muscle development and repair, activation of astrocytes in the course of brain damage and neurodegenerative processes, and of cardiomyocyte remodeling after infarction, as well as in melanomagenesis and gliomagenesis. As an extracellular factor, S100B engages RAGE (receptor for advanced glycation end products) in a variety of cell types with different outcomes (i.e. beneficial or detrimental, pro-proliferative or pro-differentiative) depending on the concentration attained by the protein, the cell type and the microenvironment. Yet, RAGE might not be the sole S100B receptor, and S100B's ability to engage RAGE might be regulated by its interaction with other extracellular factors. Future studies using S100B transgenic and S100B null mice might shed more light on the functional role(s) of the protein.

Biological and methodological features of the measurement of S100B, a putative marker of brain injury

The S100B astroglial protein is widely used as a parameter of glial activation and/or death in several conditions of brain injury. Cerebrospinal fluid and serum S100B variations have been proposed to evaluate clinical outcomes in these situations. Here, we briefly broach some aspects, commonly not sufficiently valorized, concerning the biology and measurements of this protein. S100B has molecular targets and activities in and outside of astrocytes, and variations of intra and extracellular content are not necessarily coupled. We discuss the extracellular origin of this protein in brain tissue, as well as extracerebral sources of this protein in serum, comparing it with other available protein markers of brain damage. The superestimation of the heterodimer S100A1-B in the current clinical literature is also analyzed. We affirm that poor dualistic views that consider S100B elevation as "bad" or "good" simplify clinical practice and delay our comprehension of the role of this protein, both in physiological conditions and in brain disorders.