ML218 modulates calcium binding protein, oxidative stress, and inflammation during ischemia-reperfusion brain injury in mice.

Cerebral ischemia disrupts calcium homeostasis in the brain causing excitotoxicity, oxidative stress, inflammation, and neuronal cell apoptosis. During ischemic conditions, T-type calcium channel channels contribute to increase in intracellular calcium ions in both neurons and glial cells therefore, the current study hypothesizes the antagonism of these channels using ML218, a novel specific T-Type inhibitor in experimental model of cerebral ischemia-reperfusion (CI/R) brain injury. CI/R injury was induced in Swiss Albino mice by occlusion of common carotid arteries followed by reperfusion. Animals were assessed for learning and memory (MWM), motor coordination (Rota rod), neurological function (neurological deficit score), cerebral infarction, edema, and histopathological alterations. Biochemical assessments were made for calcium binding proteins (Calmodulin- CaM, calcium/calmodulin-dependent protein kinase II-CaMKII, S100B), oxidative stress (4-hydroxy 2-nonenal-4-HNE, glutathione-GSH, inflammation (nuclear factor kappa-light-chain-enhancer of activated B-p65-NF-kB, tumor necrosis factor-TNF-α, interleukin-IL-10) inducible nitric oxide synthase (iNOS) levels, and acetylcholinesterase activity (AChE) in brain supernatants. Furthermore, serum levels of NF-kB, iNOS, and S100B were also assessed. CI/R animals showed impairment in learning, memory, motor coordination, and neurological function along with increase in cerebral infarction, edema, and histopathological alterations. Furthermore, increase in brain calcium binding proteins, oxidative stress, inflammation, and AChE activity along with serum NF-kB, iNOS, and S100B levels were recorded in CI/R animals. Administration of ML218 (5 mg/kg and 10 mg/kg; i.p.) was observed to recuperate CI/R induced impairments in behavioral, biochemical, and histopathological analysis. Hence, it may be concluded that ML218 mediates neuroprotection during CI/R via decreasing brain and serum calcium binding proteins, inflammation, iNOS, and oxidative stress markers.

RAGE mediates hippocampal pericyte responses and neurovascular unit lesions after TBI.

Traumatic brain injury impairs brain function through various mechanisms. Recent studies have shown that alterations in pericytes in various diseases affect neurovascular function, but the effects of TBI on hippocampal pericytes remain unclear. Here, we investigated the effects of RAGE activation on pericytes after TBI using male C57BL/6 J mice. Hippocampal samples were collected at different time points within 7 days after TBI, the expression of PDGFR-ß, NG2 and the HMGB1-S100B/RAGE signaling pathway was assessed by Western blotting, and the integrity of the hippocampal BBB at different time points was measured by immunofluorescence. RAGE-associated BBB damage in hippocampal pericytes occurred early after cortical impact. By culturing primary mouse brain microvascular pericytes, we determined the different effects of HMGB1-S100B on pericyte RAGE. To investigate whether RAGE blockade could protect neurological function after TBI, we reproduced the process of CCI by administering FPS-ZM1 to RAGE-/- mice. TEM images and BBB damage-related assays showed that inhibition of RAGE resulted in a significant improvement in the number of hippocampal vascular basement membranes and tight junctions and a reduction in perivascular oedema compared with those in the untreated group. In contrast, mouse behavioural testing and doublecortin staining indicated that targeting the HMGB1-S100B/RAGE axis after CCI could protect neurological function by reducing pericyte-associated BBB damage. In conclusion, the present study provides experimental evidence for the strong correlation between the pericyte HMGB1-S100B/RAGE axis and NVU damage in the hippocampus at the early stage of TBI and further demonstrates that pericyte RAGE serves as an important target for the protection of neurological function after TBI.

Identification of cellular and noncellular components of mature intact human peripheral nerve.

BACKGROUND AND AIMS: The goal of this study was to define basic constituents of the adult peripheral nervous system (PNS) using intact human nerve tissues. METHODS: We combined fluorescent and chromogenic immunostaining methods, myelin-selective fluorophores, and routine histological stains to identify common cellular and noncellular elements in aldehyde-fixed nerve tissue sections. We employed Schwann cell (SC)-specific markers, such as S100ß, NGFR, Sox10, and myelin protein zero (MPZ), together with axonal, extracellular matrix (collagen IV, laminin, fibronectin), and fibroblast markers to assess the SC's relationship to myelin sheaths, axons, other cell types, and the acellular environment. RESULTS: Whereas S100ß and Sox10 revealed mature SCs in the absence of other stains, discrimination between myelinating and non-myelinating (Remak) SCs required immunodetection of NGFR along with axonal and/or myelin markers. Surprisingly, our analysis of NGFR+ profiles uncovered the existence of at least 3 different novel populations of NGFR+/S100ß- cells, herein referred to as nonglial cells, residing in the stroma and perivascular areas of all nerve compartments. An important proportion of the nerve's cellular content, including circa 30% of endoneurial cells, consisted of heterogenous S100ß negative cells that were not associated with axons. Useful markers to identify the localization and diversity of nonglial cell types across different compartments were Thy1, CD34, SMA, and Glut1, a perineurial cell marker. INTERPRETATION: Our optimized methods revealed additional detailed information to update our understanding of the complexity and spatial orientation of PNS-resident cell types in humans.

Increased Permeability of the Blood-Brain Barrier in a Diabetic Mouse Model (Leprdb/db Mice).

Type 2 Diabetes Mellitus (T2DM) is linked to multiple complications, including cognitive impairment, and the prevalence of memory-related neurodegenerative diseases is higher in T2DM patients. One possible theory is the alteration of the microvascular and macrovascular environment of the blood-brain barrier (BBB). In this study, we employed different approaches, including RT-PCR, functional pharmacokinetic studies using sodium fluorescein (NaFL), and confocal microscopy, to characterize the functional and molecular integrity of the BBB in a T2DM animal model, leptin receptor-deficient mutant mice (Leprdb/db mice). As a result, VCAM-1, ICAM-1, MMP-9, and S100b (BBB-related markers) dysregulation was observed in the Leprdb/db animal model compared to littermate wild-type mice. The brain concentration of sodium fluorescein (NaFL) increased significantly in Leprdb/db untreated mice compared to insulin-treated mice. Therefore, the permeability of NaFL was higher in Leprdb/db control mice than in all remaining groups. Identifying the factors that increase the BBB in Leprdb/db mice will provide a better understanding of the BBB microvasculature and present previously undescribed findings of T2DM-related brain illnesses, filling knowledge gaps in this emerging field of research.

Kisspeptin signaling in astrocytes modulates the reproductive axis.

Reproduction is safeguarded by multiple, often cooperative, regulatory networks. Kisspeptin signaling, via KISS1R, plays a fundamental role in reproductive control, primarily by regulation of hypothalamic GnRH neurons. We disclose herein a pathway for direct kisspeptin actions in astrocytes that contributes to central reproductive modulation. Protein-protein interaction and ontology analyses of hypothalamic proteomic profiles after kisspeptin stimulation revealed that glial/astrocyte markers are regulated by kisspeptin in mice. This glial-kisspeptin pathway was validated by the demonstrated expression of Kiss1r in mouse astrocytes in vivo and astrocyte cultures from humans, rats, and mice, where kisspeptin activated canonical intracellular signaling-pathways. Cellular coexpression of Kiss1r with the astrocyte markers GFAP and S100-ß occurred in different brain regions, with higher percentage in Kiss1- and GnRH-enriched areas. Conditional ablation of Kiss1r in GFAP-positive cells in the G-KiR-KO mouse altered gene expression of key factors in PGE2 synthesis in astrocytes and perturbed astrocyte-GnRH neuronal appositions, as well as LH responses to kisspeptin and LH pulsatility, as surrogate marker of GnRH secretion. G-KiR-KO mice also displayed changes in reproductive responses to metabolic stress induced by high-fat diet, affecting female pubertal onset, estrous cyclicity, and LH-secretory profiles. Our data unveil a nonneuronal pathway for kisspeptin actions in astrocytes, which cooperates in fine-tuning the reproductive axis and its responses to metabolic stress.

Spatial transcriptomic analysis of amelanotic acral melanoma versus pigmented acral melanoma reveals distinct molecular determinants.

BACKGROUND: Amelanotic acral melanoma (AAM) is a rare type of acral melanoma that has a poor prognosis. OBJECTIVES: To investigate the transcriptomic differences between AAM and pigmented acral melanoma (PAM). METHODS: Differences in the spatially resolved transcriptomic profiles of 9 patients with AAM with 29 regions of interest (ROIs) and 11 patients with PAM with 46 ROIs were investigated using S100b and CD3 morphology markers. RESULTS: In S100b+ tumour cell areas, we detected 11 upregulated differentially expressed genes (DEGs; including chaperone/ubiquitin--associated DEGs) and 82 downregulated DEGs (including human leucocyte antigen) in AAMs vs. PAMs. Protein-protein interaction network and pathway analyses revealed significant enrichment of dysregulated translational and nonsense-mediated decay pathways but significant decreases in antigen processing and presentation, interferon signalling and melanin biosynthesis pathways in S100b+ ROIs of AAMs compared with PAMs. In tumour-associated immune cell areas, the numbers of CD8 T cells (P = 0.04) and M1 macrophages (P = 0.01) were significantly decreased, whereas those of monocytes (P = 0.04) and endothelial cells (P = 0.04) were increased in AAMs compared with PAMs. CONCLUSIONS: These findings could widen our understanding of the biological differences between AAMs and PAMs, which might result in a different clinical course.

Melanoma is one of the most serious types of skin cancer. As melanoma starts in cells that produce melanin (the substance that produces hair, eye and skin colouration), melanoma tumours are usually brown or black. 'Amelanotic melanoma' is a subtype of melanoma that has little or no melanin pigmentation. Less than 2% of melanomas are amelanotic melanomas. 'Acral melanoma' is a type of melanoma that occurs on the hands and feet. In acral melanoma, the lack of pigmentation has been associated with worse outcomes for patients. Why amelanotic acral melanoma (or 'AAM') has a worse prognosis than pigmented acral melanoma (or 'PAM') is unclear. Using a type of technology called 'spatial transcriptomic analysis', we analysed a type of nucleic acid called RNA in 9 people with AAM and 11 with PAM. Seventy-five 'regions of interest' were selected. These regions of interest are known to be associated with tumour cells or immune cells around tumours. We found that pathways involved in making proteins (translation) and in a process that removes faulty proteins called 'messenger RNA' were more active in AAM. However, pathways involved in processing and presenting antigens (substances that can trigger an immune response), the signalling of other proteins called 'interferons' and melanin production were less active in AAM. The number of specific types of white blood cells that recognize and attack tumours were decreased, whereas other cell types such as cells that line blood vessels were increased in AAM. Our findings could increase our understanding of the differences between AAMs and PAMs. This may lead to an improvement in prognosis.

Clinical effect of external ventricular drainage under intracranial pressure monitoring in the treatment of aneurysmal subarachnoid hemorrhage patients and investigation of the mechanism of miR-146a-5p/STC1 axis in inhibiting early brain injury in aneurys.

Aneurismal subarachnoid hemorrhage (aSAH) is a common disease in the neural system, with high death rate. Our study aimed to explore the clinical effect of external ventricular drainage under intracranial pressure monitoring in the treatment of patients with aSAH and investigate the role along with mechanism of miR-146a-5p in aSAH. Ninety-six aSAH patients were allocated into control group (CG) and study group (SG). The CG was released by lumbar puncture. The SG underwent external ventricular drainage based on intracranial pressure monitoring. The prognosis, daily living ability, neurological function, S100ß and NSE (neuron-specific enolase) levels and incidence of complications were monitored. Besides, a rat model of SAH was built to assess the neurobehavioral function, blood-brain barrier permeability, brain water content, neuronal apoptosis as well as inflammation. SAH cell model stimulated by oxyhemoglobin, and cell apoptosis as well as inflammation were measured. Luciferase reporter assay was implemented to explore the interaction between miR-146a-5p and STC1. Results showed higher GOS and BI scores but lower NIHSS scores, S100ß and NSE levels and complication rates in SG compared with CG. Additionally, miR-146a-5p presented down-regulation in brain tissues of SAH rat model, and overexpressed miR-146a-5p reduced brain injury along with neuroinflammation in SAH rat model. Oxyhemoglobin-induced nerve cell apoptosis along with inflammation after SAH, and overexpressed miR-146a-5p repressed oxyhemoglobin-induced nerve cell apoptosis along with inflammation. STC1 is the target mRNA of miR-146a-5p, and overexpressed miR-146a-5p represses oxyhemoglobin-induced nerve cell apoptosis along with inflammation via regulating STC1 expression. In conclusion, external ventricular drainage under intracranial pressure monitoring could promote prognosis, promote daily living ability, improve neurological function, reduce S100ß protein and NSE levels, and reduce the incidence of complications in patients with aSAH. Meanwhile, miR-146a-5p inhibited early brain injury and neuroinflammation in aSAH via regulating STC1 expression.

Is Methylglyoxal a Potential Biomarker for the Warburg Effect Induced by the Lipopolysaccharide Neuroinflammation Model?

Methylglyoxal (MG) is considered a classical biomarker of diabetes mellitus and its comorbidities. However, a role for this compound in exacerbated immune responses, such as septicemia, is being increasingly observed and requires clarification, particularly in the context of neuroinflammatory responses. Herein, we used two different approaches (in vivo and acute hippocampal slice models) to investigate MG as a biomarker of neuroinflammation and the neuroimmunometabolic shift to glycolysis in lipopolysaccharide (LPS) inflammation models. Our data reinforce the hypothesis that LPS-induced neuroinflammation stimulates the cerebral innate immune response by increasing IL-1ß, a classical pro-inflammatory cytokine, and the astrocyte reactive response, via elevating S100B secretion and GFAP levels. Acute neuroinflammation promotes an early neuroimmunometabolic shift to glycolysis by elevating glucose uptake, lactate release, PFK1, and PK activities. We observed high serum and cerebral MG levels, in association with a reduction in glyoxalase 1 detoxification activity, and a close correlation between serum and hippocampus MG levels with the systemic and neuroinflammatory responses to LPS. Findings strongly suggest a role for MG in immune responses.

Ac2-26 activated the AKT1/GSK3ß pathway to reduce cerebral neurons pyroptosis and improve cerebral function in rats after cardiopulmonary bypass.

BACKGROUND: Cardiopulmonary bypass (CPB) results in brain injury, which is primarily caused by inflammation. Ac2-26 protects against ischemic or hemorrhage brain injury. The present study was to explore the effect and mechanism of Ac2-26 on brain injury in CPB rats. METHODS: Forty-eight rats were randomized into sham, CPB, Ac, Ac/AKT1, Ac/GSK3ßi and Ac/AKT1/GSK3ßa groups. Rats in sham group only received anesthesia and in the other groups received standard CPB surgery. Rats in the sham and CPB groups received saline, and rats in the Ac, Ac/AKT1, Ac/GSK3ßi and Ac/AKT1/GSK3ßa groups received Ac2-26 immediately after CPB. Rats in the Ac/AKT1, Ac/GSK3ßi and Ac/AKT1/GSK3ßa groups were injected with shRNA, inhibitor and agonist of GSK3ß respectively. The neurological function score, brain edema and histological score were evaluated. The neuronal survival and hippocampal pyroptosis were assessed. The cytokines, activity of NF-κB, S100 calcium-binding protein ß(S100ß) and neuron-specific enolase (NSE), and oxidative were tested. The NLRP3, cleaved-caspase-1 and cleaved-gadermin D (GSDMD) in the brain were also detected. RESULTS: Compared to the sham group, all indicators were aggravated in rats that underwent CPB. Compared to the CPB group, Ac2-26 significantly improved neurological scores and brain edema and ameliorated pathological injury. Ac2-26 reduced the local and systemic inflammation, oxidative stress response and promoted neuronal survival. Ac2-26 reduced hippocampal pyroptosis and decreased pyroptotic proteins in brain tissue. The protection of Ac2-26 was notably lessened by shRNA and inhibitor of GSK3ß. The agonist of GSK3ß recovered the protection of Ac2-26 in presence of shRNA. CONCLUSIONS: Ac2-26 significantly improved neurological function, reduced brain injury via regulating inflammation, oxidative stress response and pyroptosis after CPB. The protective effect of Ac2-26 primarily depended on AKT1/ GSK3ß pathway.

Blood brain barrier permeability and astrocyte-derived extracellular vesicles in children with juvenile idiopathic arthritis: a cross-sectional study.

BACKGROUND: Juvenile idiopathic arthritis (JIA) is the most prevalent rheumatic disease in children, and the inflammatory process is widely studied, primarily characterized by its impact on joint health. Emerging evidence suggests that JIA may also affect the central nervous system (CNS). This study investigates the potential CNS involvement in JIA by analyzing the presence of astrocyte-derived extracellular vesicles (EVs) and the S100B protein in plasma, both of which are indicative of astrocyte activity and blood-brain barrier (BBB) integrity. METHODS: EDTA plasma from 90 children diagnosed with JIA and 10 healthy controls, matched by age and gender, was analyzed for extracellular vesicles by flow cytometric measurement. Astrocyte-derived EVs were identified using flow cytometry with markers for aquaporin 4 (AQP-4) and glial fibrillary acidic protein (GFAP). Levels of the S100B protein were measured using a commercial ELISA. Disease activity was assessed using the Juvenile Arthritis Disease Activity Score (JADAS27, 0-57), and pain levels were measured using a visual analogue scale (VAS, 0-10 cm). RESULTS: Our analyses revealed a significantly higher concentration of astrocyte-derived EVs in the plasma of children with JIA compared with healthy controls. Furthermore, children with JADAS27 scores of 1 or higher exhibited notably higher levels of these EVs. The S100B protein was detectable exclusively in the JIA group. CONCLUSION: The elevated levels of astrocyte-derived EVs and the presence of S100B in children with JIA provide evidence of BBB disruption and CNS involvement, particularly in those with higher disease activity. These findings underscore the importance of considering CNS health in the comprehensive management of JIA. Further research is required to elucidate the mechanisms behind CNS engagement in JIA and to develop treatments that address both joint and CNS manifestations of the disease.

Lipid peroxidation-induced ferroptosis as a therapeutic target for mitigating neuronal injury and inflammation in sepsis-associated encephalopathy: insights into the hippocampal PEBP-1/15-LOX/GPX4 pathway.

BACKGROUND: Sepsis-associated encephalopathy (SAE) refers to the widespread impairment of brain function caused by noncentral nervous system infection mediated by sepsis. Lipid peroxidation-induced ferroptosis contributes to the occurrence and course of SAE. This study aimed to investigate the relationship between neuronal injury and lipid peroxidation-induced ferroptosis in SAE. METHODS: Baseline data were collected from pediatric patients upon admission, and the expression levels of various markers related to lipid peroxidation and ferroptosis were monitored in the serum and peripheral blood mononuclear cells (PBMCs) of patients with SAE as well as SAE model mice. The hippocampal phosphatidylethanolamine-binding protein (PEBP)-1/15-lysine oxidase (LOX)/ glutathione peroxidase 4 (GPX4) pathway was assessed for its role on the inhibitory effect of ferroptosis in SAE treatment. RESULTS: The results showed elevated levels of S100 calcium-binding protein beta (S-100ß), glial fibrillary acidic protein, and malondialdehyde in the serum of SAE patients, while superoxide dismutase levels were reduced. Furthermore, analysis of PBMCs revealed increased transcription levels of PEBP1, LOX, and long-chain fatty acyl-CoA synthetase family member 4 (ACSL4) in SAE patients, while the transcription levels of GPX4 and cystine/glutamate transporter xCT (SLC7A11) were decreased. In comparison to the control group, the SAE mice exhibited increased expression of S-100ß and neuron-specific enolase (NSE) in the hippocampus, whereas the expression of S-100ß and NSE were reduced in deferoxamine (DFO) mice. Additionally, iron accumulation was observed in the hippocampus of SAE mice, while the iron ion levels were reduced in the DFO mice. Inhibition of ferroptosis alleviated the mitochondrial damage (as assessed by transmission electron microscopy, hippocampal mitochondrial ATP detection, and the JC-1 polymer-to-monomer ratio in the hippocampus) and the oxidative stress response induced by SAE as well as attenuated neuroinflammatory reactions. Further investigations revealed that the mechanism underlying the inhibitory effect of ferroptosis in SAE treatment is associated with the hippocampal PEBP-1/15-LOX/GPX4 pathway. CONCLUSION: These results offer potential therapeutic targets for the management of neuronal injury in SAE and valuable insights into the potential mechanisms of ferroptosis in neurological disorders.

Deciphering S100B Allosteric Signaling: The Role of a Peptide Target, TRTK-12, as an Ensemble Modulator.

Allostery is an essential biological phenomenon in which perturbation at one site in a biomolecule elicits a functional response at a distal location(s). It is integral to biological processes, such as cellular signaling, metabolism, and transcription regulation. Understanding allostery is also crucial for rational drug discovery. In this work, we focus on an allosteric S100B protein that belongs to the S100 class of EF-hand Ca2+-binding proteins. The Ca2+-binding affinity of S100B is modulated allosterically by TRTK-12 peptide binding 25 Å away from the Ca2+-binding site. We investigated S100B allostery by carrying out nuclear magnetic resonance (NMR) measurements along with microsecond-long molecular dynamics (MD) simulations on S100B/Ca2+ with/without TRTK-12 at different NaCl salt concentrations. NMR HSQC results show that TRTK-12 reorganizes how S100B/Ca2+ responds to different salt concentrations at both orthosteric and allosteric sites. The MD data suggest that TRTK-12 breaks the dynamic aromatic and hydrogen-bond interactions (not observed in X-ray crystallographic structures) between the hinge/helix and Ca2+-binding EF-hand loop of the two subunits in the homodimeric protein. This triggers rearrangement in the protein network architectures and leads to allosteric communication. Finally, computational studies of S100B at distinct ionic strengths suggest that ligand-bound species are more robust to the changing environment relative to the S100B/Ca2+ complex.

Selective brain perfusion improves the neurological outcomes after extracorporeal cardiopulmonary resuscitation in a rat model.

BACKGROUND: The major concern in patients who have suffered from cardiac arrest (CA) and undergone successful extracorporeal cardiopulmonary resuscitation (E-CPR) is poor neurological outcomes. In this study, we aimed to introduce a rat model of selective brain perfusion (SBP) during E-CPR to improve the neurological outcome after CA. METHODS: The rats underwent 7 min of untreated asphyxial CA and then were resuscitated with E-CPR for 30 min. The right external jugular vein and right femoral artery were separately cannulated to the E-CPR outflow and inflow. The right common carotid artery was cannulated from the proximal to the distal side for SBP. Subsequently, rats were removed from E-CPR, wounds were closed, and 90 min of intensive care were provided. Neurological deficit scores were tested after 4 h of recovery when the rats were mechanical ventilation-free. S100 calcium-binding protein B (S100B) and glial fibrillary acidic protein (GFAP) were detected through immunohistochemistry (IHC) of brain tissue. RESULTS: The rats that received SBP while resuscitated by E-CPR showed markedly better neurological performances after 4-h recovery than those resuscitated by E-CPR only. The IHC staining of GFAP and S100B in the hippocampus was low in the rats receiving SBP during E-CPR, but only GFAP showed significant differences. CONCLUSIONS: We successfully developed a novel and reproducible rat model of SBP while resuscitated by E-CPR to ameliorate the neurological performances after CA. This achievement might have opportunities for studying how to improve the neurological outcome in the clinical condition.

Secondary Modification of S100B Influences Anti Amyloid-ß Aggregation Activity and Alzheimer's Disease Pathology.

Proteinaceous aggregates accumulate in neurodegenerative diseases such as Alzheimer's Disease (AD), inducing cellular defense mechanisms and altering the redox status. S100 pro-inflammatory cytokines, particularly S100B, are activated during AD, but recent findings reveal an unconventional molecular chaperone role for S100B in hindering Aß aggregation and toxicity. This suggests a potential protective role for S100B at the onset of Aß proteotoxicity, occurring in a complex biochemical environment prone to oxidative damage. Herein, we report an investigation in which extracellular oxidative conditions are mimicked to test if the susceptibility of S100B to oxidation influences its protective activities. Resorting to mild oxidation of S100B, we observed methionine oxidation as inferred from mass spectrometry, but no cysteine-mediated crosslinking. Structural analysis showed that the folding, structure, and stability of oxidized S100B were not affected, and nor was its quaternary structure. However, studies on Aß aggregation kinetics indicated that oxidized S100B was more effective in preventing aggregation, potentially linked to the oxidation of Met residues within the S100:Aß binding cleft that favors interactions. Using a cell culture model to analyze the S100B functions in a highly oxidative milieu, as in AD, we observed that Aß toxicity is rescued by the co-administration of oxidized S100B to a greater extent than by S100B. Additionally, results suggest a disrupted positive feedback loop involving S100B which is caused by its oxidation, leading to the downstream regulation of IL-17 and IFN-α2 expression as mediated by S100B.

Astroglial S100B Secretion Is Mediated by Ca2+ Mobilization from Endoplasmic Reticulum: A Study Using Forskolin and DMSO as Secretagogues.

S100B, a homodimeric Ca2+-binding protein, is produced and secreted by astrocytes, and its extracellular levels have been used as a glial marker in brain damage and neurodegenerative and psychiatric diseases; however, its mechanism of secretion is elusive. We used primary astrocyte cultures and calcium measurements from real-time fluorescence microscopy to investigate the role of intracellular calcium in S100B secretion. In addition, the dimethyl sulfoxide (DMSO) effect on S100B was investigated in vitro and in vivo using Wistar rats. We found that DMSO, a widely used vehicle in biological assays, is a powerful S100B secretagogue, which caused a biphasic response of Ca2+ mobilization. Our data show that astroglial S100B secretion is triggered by the increase in intracellular Ca2+ and indicate that this increase is due to Ca2+ mobilization from the endoplasmic reticulum. Also, blocking plasma membrane Ca2+ channels involved in the Ca2+ replenishment of internal stores decreased S100B secretion. The DMSO-induced S100B secretion was confirmed in vivo and in ex vivo hippocampal slices. Our data support a nonclassic vesicular export of S100B modulated by Ca2+, and the results might contribute to understanding the mechanism underlying the astroglial release of S100B.

How S100B crosses brain barriers and why it is considered a peripheral marker of brain injury.

S100B is a 21-kDa protein that is produced and secreted by astrocytes and widely used as a marker of brain injury in clinical and experimental studies. The majority of these studies are based on measurements in blood serum, assuming an associated increase in cerebrospinal fluid and a rupture of the blood-brain barrier (BBB). Moreover, extracerebral sources of S100B are often underestimated. Herein, we will review these interpretations and discuss the routes by which S100B, produced by astrocytes, reaches the circulatory system. We discuss the concept of S100B as an alarmin and its dual activity as an inflammatory and neurotrophic molecule. Furthermore, we emphasize the lack of data supporting the idea that S100B acts as a marker of BBB rupture, and the need to include the glymphatic system in the interpretations of serum changes of S100B. The review is also dedicated to valorizing extracerebral sources of S100B, particularly adipocytes. Furthermore, S100B per se may have direct and indirect modulating roles in brain barriers: on the tight junctions that regulate paracellular transport; on the expression of its receptor, RAGE, which is involved in transcellular protein transport; and on aquaporin-4, a key protein in the glymphatic system that is responsible for the clearance of extracellular proteins from the central nervous system. We hope that the data on S100B, discussed here, will be useful and that it will translate into further health benefits in medical practice.

Diclofenac sodium and dexamethasone co-therapy restores brain neuron-specific enolase (NSE), S-100 Beta and glial fibrillary acid protein (GFAP) proteins in experimental rat's model: A possible inhibition of P-glycoprotein.

Non-steroidal anti-inflammatory drugs decrease pain and fever while corticosteroids regulate inflammation and immune response, both are prescribed to reduce inflammation and control pain. The present study aimed to study the effects of their monotherapy and co-administration on the brain tissue structure of experimental rats. P-glycoprotein (PGP), a transporter membrane protein, plays an important role in various physiological and physio-pathological conditions, drug-drug and drug-food interactions, and multi-drug resistance. Male rats were divided into four groups and received normal saline, dexamethasone, diclofenac sodium and their dual therapy respectively, then after one-month rats were sacrificed and brain tissues proceeded for hematoxylin and eosin staining to study their histopathology and immunohistochemically staining of NSE, S100-B and GFAP biomarkers were performed. Additionally, in silico molecular docking studies were conducted to elucidate interactions between PGP and used compounds. Resultsshowed that dexamethasone or diclofenac sodium treatments showed abnormalities like edema, neuronal vacuoles, astrocytes hyperplasia and microglial cells with positive reaction to NSE, S100 and GFAP antibodies while the dual therapy displayed less edema and other signs of damage with negative and weak positive staining of NSE, S100 and GFAP antibodies respectively. The molecular docking showed that there were different affinities toward the involved PGP active site. These interaction results were great with Dexamethasone -9.6 kcal/mol forming hydrophobic interactions with the highest affinity when compared with Diclofenac sodium which gave -8.4 kcal/mol. In conclusion, the side effects of the two types of anti-inflammatory drugs may be minimized through their interactions. However, Molecular Dynamic Simulations studies are required to explain the exact dynamic behaviors and protein-ligand stability.

The beneficial effects of vortioxetine on BDNF, CREB, S100B, ß amyloid, and glutamate NR2b receptors in chronic unpredictable mild stress model of depression.

BACKGROUND: Depression, one of the most significant mental disorders, is still poorly understood in terms of its pathogenetic mechanisms despite its well-recognized association with stress. OBJECTIVES: The current study's goal was to ascertain how the novel antidepressant drug vortioxetine (VOR) affected the BDNF (brain-derived neurotrophic factor), S100, amyloid ß (Aß), CREB (cAMP response element-binding protein), and NR2B, as well as its impact on depression-like behaviors, and tissue damage in an experimental rodent model of depression caused by chronic unpredictable stress. METHODS: We employed twenty-eight Wistar albino male rats, and we randomly divided them into four groups, each consisting of 7 rats: control, CUMS (chronic unpredictable mild stress), CUMS+vortioxetine (CUMS+VOR), and CUMS+fluoxetine (CUMS+FLU). Sucrose preference and forced swimming tests (SPT and FST, respectively), PCR, ELISA, and histopathological and immunohistochemical evaluation were made on brains. RESULTS: The behaviors of reduced immobility in the FST and increased sucrose preference were observed in the CUMS group and they improved in the groups treated with VOR and FLU. Compared with the control group, the group exposed to CUMS showed increased Aß and decreased BDNF, CREB, and S-100 expressions, as well as neuronal degeneration (p<0.001). VOR and FLU treatment ameliorate the findings. CONCLUSIONS: This study demonstrated significant ameliorative effects of VOR in an experimental model of chronic unpredictable depression to reduce brain tissue damage and depression-like behaviors in rats. Effects of CUMS on the brain and possible effects of VOR.

Mini review: Current status and perspective of S100B protein as a biomarker in daily clinical practice for diagnosis and prognosticating of clinical outcome in patients with neurological diseases with focus on acute brain injury.

Prognosticating the clinical outcome of neurological diseases is essential to guide treatment and facilitate decision-making. It usually depends on clinical and radiological findings. Biomarkers have been suggested to support this process, as they are deemed objective measures and can express the extent of tissue damage or reflect the degree of inflammation. Some of them are specific, and some are not. Few of them, however, reached the stage of daily application in clinical practice. This mini review covers available applications of the S100B protein in prognosticating clinical outcome in patients with various neurological disorders, particularly in those with traumatic brain injury, spontaneous subarachnoid hemorrhage and ischemic stroke. The aim is to provide an understandable picture of the clinical use of the S100B protein and give a brief overview of the current limitations that require future solutions.

Characterization of Macroglia Response during Tissue Repair in a Laser-Induced Model of Retinal Degeneration.

Reactive gliosis is a hallmark of chronic degenerative diseases of the retina. As gliosis involves macroglia, we investigated their gliotic response to determine the role of S100ß and intermediate filaments (IFs) GFAP, vimentin, and nestin during tissue repair in a laser-induced model of retinal degeneration. We validated the results with human retinal donor samples. Experiments were performed in zebrafish and mice using an argon laser (532 nm) to induce focal lesions in the outer retina. At different time points following injury induction, the kinetics of retinal degeneration and regeneration were assessed using hematoxylin and eosin staining (H&E). Immunofluorescence was performed to evaluate Müller cell (GS) and astrocyte (GFAP) injury response and to distinguish between both cell types. Additionally, staining was performed in human retinal sections containing drusen. Focal laser treatment elevated the expression of gliotic markers in the area of the damage, which was associated with increased expression of S100ß, GFAP, vimentin, and nestin in mice and humans. In zebrafish, we detected S100ß at the first time point, but not GFAP or nestin. Double-positive cells with the selected glia markers were detected in all models. However, in zebrafish, no double-positive GFAP/GS cells were found on days 10 and 17, nor were S100ß/GS double-positive cells found on day 12. Macroglia cells showed a different pattern in the expression of IFs in degenerative and regenerative models. In particular, S100ß may prove to be a target for suppressing chronic gliosis in retinal degeneration.