The Impact of CXCR4 Blockade on the Survival of Rat Brain Cortical Neurons.

BACKGROUND: Chemokine receptor type 4 (CXCR4) plays a role in neuronal survival/cell repair and also contributes to the progression of cancer and neurodegenerative diseases. Chemokine ligand 12 (CXCL12) binds to CXCR4. In this study, we have investigated whether CXCR4 blockade by AMD3100 (a CXCR4 antagonist, member of bicyclam family) may affect neuronal survival in the absence of insult. Thus, we have measured the mitochondrial membrane potential (MMP), Bax and Bcl-2 protein translocation, and cytochrome c release in AMD3100-treated brain cortical neurons at 7 DIV (days in vitro). METHODS: For this aim, AMD3100 (200 nM) was added to cortical neurons for 24 h, and several biomarkers like cell viability, reactive oxygen species (ROS) generation, lactate dehydrogenase (LDH) release, caspase-3/9 activity, proteins Bax and Bcl-2 translocation, and cytochrome c release were analyzed by immunoblot. RESULTS: CXCR4 blockade by AMD3100 (200 nM, 24 h) induces mitochondrial hyperpolarization and increases caspase-3/9 hyperpolarization without affecting LDH release as compared to untreated controls. AMD3100 also increases cytochrome c release and promotes Bax translocation to the mitochondria, whereas it raises cytosolic Bcl-2 levels in brain cortical neurons. CONCLUSION: CXCR4 blockade induces cellular death via intrinsic apoptosis in rat brain cortical neurons in absence of insult.

CXCR4/CXCR7 molecular involvement in neuronal and neural progenitor migration: focus in CNS repair.

In the adult brain, neural progenitor cells (NPCs) reside in the subventricular zone (SVZ) of the lateral ventricles, the dentate gyrus and the olfactory bulb. Following CNS insult, NPCs from the SVZ can migrate along the rostral migratory stream (RMS), a migration of NPCs that is directed by proinflammatory cytokines. Cells expressing CXCR4 follow a homing signal that ultimately leads to neuronal integration and CNS repair, although such molecules can also promote NPC quiescence. The ligand, SDF1 alpha (or CXCL12) is one of the chemokines secreted at sites of injury that it is known to attract NSC-derived neuroblasts, cells that express CXCR4. In function of its concentration, CXCL12 can induce different responses, promoting NPC migration at low concentrations while favoring cell adhesion via EGF and the alpha 6 integrin at high CXCL12 concentrations. However, the preclinical effectiveness of chemokines and their relationship with NPC mobilization requires further study, particularly with respect to CNS repair. NPC migration may also be affected by the release of cytokines or chemokines induced by local inflammation, through autocrine or paracrine mechanisms, as well as through erythropoietin (EPO) or nitric oxide (NO) release. CXCL12 activity requires G-coupled proteins and the availability of its ligand may be modulated by its binding to CXCR7, for which it shows a stronger affinity than for CXCR4.

Antioxidant and protective mechanisms against hypoxia and hypoglycaemia in cortical neurons in vitro.

In the present work, we have studied whether cell death could be induced in cortical neurons from rats subjected to different period of O2 deprivation and low glucose (ODLG). This "in vitro" model is designed to emulate the penumbra area under ischemia. In these conditions, cortical neurons displayed loss of mitochondrial respiratory ability however, nor necrosis neither apoptosis occurred despite ROS production. The absence of cellular death could be a consequence of increased antioxidant responses such as superoxide dismutase-1 (SOD1) and GPX3. In addition, the levels of reduced glutathione were augmented and HIF-1/3α overexpressed. After long periods of ODLG (12-24 h) cortical neurons showed cellular and mitochondrial membrane alterations and did not recuperate cellular viability during reperfusion. This could mean that therapies directed toward prevention of cellular and mitochondrial membrane imbalance or cell death through mechanisms other than necrosis or apoptosis, like authophagy, may be a way to prevent ODLG damage.

Chemotactic and mitogenic stimuli of neuronal apoptosis in patients with medically intractable temporal lobe epilepsy.

To identify the upstream signals of neuronal apoptosis in patients with medically intractable temporal lobe epilepsy (TLE), we evaluated by immunohistochemistry and confocal microscopy brain tissues of 13 TLE patients and 5 control patients regarding expression of chemokines and cell-cycle proteins. The chemokine RANTES (CCR5) and other CC-chemokines and apoptotic markers (caspase-3, -8, -9) were expressed in lateral temporal cortical and hippocampal neurons of TLE patients, but not in neurons of control cases. The chemokine RANTES is usually found in cytoplasmic and extracellular locations. However, in TLE neurons, RANTES was displayed in an unusual location, the neuronal nuclei. In addition, the cell-cycle regulatory transcription factor E2F1 was found in an abnormal location in neuronal cytoplasm. The pro-inflammatory enzyme cyclooxygenase-2 and cytokine interleukin-1ß were expressed both in neurons of patients suffering from temporal lobe epilepsy and from cerebral trauma. The vessels showed fibrin leakage, perivascular macrophages and expression of IL-6 on endothelial cells. In conclusion, the cytoplasmic effects of E2F1 and nuclear effects of RANTES might have novel roles in neuronal apoptosis of TLE neurons and indicate a need to develop new medical and/or surgical neuroprotective strategies against apoptotic signaling by these molecules. Both RANTES and E2F1 signaling are upstream from caspase activation, thus the antagonists of RANTES and/or E2F1 blockade might be neuroprotective for patients with medically intractable temporal lobe epilepsy. The results have implications for the development of new medical and surgical therapies based on inhibition of chemotactic and mitogenic stimuli of neuronal apoptosis in patients with medically intractable temporal lobe epilepsy.

Nanoparticles and Mesenchymal Stem Cell (MSC) Therapy for Cancer Treatment: Focus on Nanocarriers and a si-RNA CXCR4 Chemokine Blocker as Strategies for Tumor Eradication In Vitro and In Vivo.

Mesenchymal stem cells (MSCs) have a high tropism for the hypoxic microenvironment of tumors. The combination of nanoparticles in MSCs decreases tumor growth in vitro as well as in rodent models of cancers in vivo. Covalent conjugation of nanoparticles with the surface of MSCs can significantly increase the drug load delivery in tumor sites. Nanoparticle-based anti-angiogenic systems (gold, silica and silicates, diamond, silver, and copper) prevented tumor growth in vitro. For example, glycolic acid polyconjugates enhance nanoparticle drug delivery and have been reported in human MSCs. Labeling with fluorescent particles (coumarin-6 dye) identified tumor cells using fluorescence emission in tissues; the conjugation of different types of nanoparticles in MSCs ensured success and feasibility by tracking the migration and its intratumor detection using non-invasive imaging techniques. However, the biosafety and efficacy; long-term stability of nanoparticles, and the capacity for drug release must be improved for clinical implementation. In fact, MSCs are vehicles for drug delivery with nanoparticles and also show low toxicity but inefficient accumulation in tumor sites by clearance of reticuloendothelial organs. To solve these problems, the internalization or conjugation of drug-loaded nanoparticles should be improved in MSCs. Finally, CXCR4 may prove to be a promising target for immunotherapy and cancer treatment since the delivery of siRNA to knock down this alpha chemokine receptor or CXCR4 antagonism has been shown to disrupt tumor-stromal interactions.

Adult Mesenchymal Stem Cells from Oral Cavity and Surrounding Areas: Types and Biomedical Applications.

Adult mesenchymal stem cells are those obtained from the conformation of dental structures (DMSC), such as deciduous and permanent teeth and other surrounding tissues. Background: The self-renewal and differentiation capacities of these adult stem cells allow for great clinical potential. Because DMSC are cells of ectomesenchymal origin, they reveal a high capacity for complete regeneration of dental pulp, periodontal tissue, and other biomedical applications; their differentiation into other types of cells promotes repair in muscle tissue, cardiac, pancreatic, nervous, bone, cartilage, skin, and corneal tissues, among others, with a high predictability of success. Therefore, stem and progenitor cells, with their exosomes of dental origin and surrounding areas in the oral cavity due to their plasticity, are considered a fundamental pillar in medicine and regenerative dentistry. Tissue engineering (MSCs, scaffolds, and bioactive molecules) sustains and induces its multipotent and immunomodulatory effects. It is of vital importance to guarantee the safety and efficacy of the procedures designed for patients, and for this purpose, more clinical trials are needed to increase the efficacy of several pathologies. Conclusion: From a bioethical and transcendental anthropological point of view, the human person as a unique being facilitates better clinical and personalized therapy, given the higher prevalence of dental and chronic systemic diseases.

The Bluegreen Algae (AFA) Consumption over 48 Hours Increases the Total Number of Peripheral CD34+ Cells in Healthy Patients: Effect of Short-Term and Long-Term Nutritional Supplementation (Curcumin/AFA) on CD34+ Levels (Blood).

Several active principles from plants could trigger the release of stem cells from the bone marrow. Stem cell mobilizers have shown side effects in patients. Thus, the purpose of this paper is to find the natural products from plants (curcuminoids, glycosinolate of sulforaphane, AFA bluegreen algae), which could be potential stem mobilizes without adverse side effects. The antioxidant curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-2,5-dione], glycosinolate of sulforaphane (broccoli) or AFA (Aphanizomenon flos) extract promote beneficial effects in patients. The number of circulating stem cells were monitored by HSC marker-CD34 by flow cytometry in peripheral blood from healthy subjects. CD34 is a hematological stem cells (HSC) marker. A double-blind study was conducted in 22 healthy subjects. We have evaluated whether short-term AFA-Aphanizomenon flos aquae-algae or curcuminoids consumption (powder or liquid formulation) over 48 consecutive hours could increase the total number of peripheral CD34+ blood cells (n = 22, n = 5 subjects/group). The total number of circulating CD34+ cells were quantified after short-term and long-term nutritional supplementation; their levels were compared with their own basal levels (n = 5/group, controls: before taking any supplement) or placebo-treated patients (n = 7); their average age was 54 years old. We also evaluated whether long-term nutritional supplementation with several nutraceuticals could enhance HSC mobilization by increasing the total number of peripheral CD-34+ cell after seven or 38 consecutive days of administration (n = 5, with seven placebo-treated patients). The long-term administration take place with these doses/day [curcuminoids: 2000 mg/day, equivalent to 120 mg of curcuminoids/day), glycosinolate of sulforaphane (66 mg/day), plus AFA Algae bluegreen extract (400 mg/day)]. On the last day (10 A.M.) of treatment, blood samples were collected six hours after taking these supplements; the average age was 54 years old. Notably, the blue green AFA algae extract consumption over 48 h enhances HSC mobilization by increasing the total number of peripheral CD34+ cells. The long-term administration with curcuminoids, glycosinolate of sulforaphane, and AFA bluegreen algae extract also increased the total number of CD34-HSC cells after seven or 38 days of consecutive of administration in healthy subjects.

Hippocampal CCR5/RANTES Elevations in a Rodent Model of Post-Traumatic Stress Disorder: Maraviroc (a CCR5 Antagonist) Increases Corticosterone Levels and Enhances Fear Memory Consolidation.

BACKGROUND: Contextual fear conditioning (CFC) is a rodent model that induces a high and long-lasting level of conditioning associated with traumatic memory formation; this behavioral paradigm resembles many characteristics of posttraumatic stress disorder (PSTD). Chemokines (chemotactic cytokines) play a known role in neuronal migration and neurodegeneration but their role in cognition is not totally elucidated. AIM: We ascertain whether CCR5/RANTES beta chemokines (hippocampus/prefrontal cortex) could play a role in fear memory consolidation (CFC paradigm). We also evaluated whether chronic stress restraint (21 days of restraint, 6-h/day) could regulate levels of these beta chemokines in CFC-trained rats; fear memory retention was determined taking the level of freezing (context and tone) by the animals as an index of fear memory consolidation 24 h after CFC training session; these chemokines (CCR5/RANTES) and IL-6 levels were measured in the hippocampus and prefrontal cortex of chronically stressed rats, 24 h after CFC post-training, and compared with undisturbed CFC-trained rats (Experiment 1). In Experiment 2, rats received 1 mA of footshock during the CFC training session and fear memory consolidation was evaluated at 12 and 24 h after CFC training sessions. We evaluated whether RANTES levels could be differentially regulated at 12 and 24 h after CFC training; in Experiment 3, maraviroc was administered to rats (i.m: 100 mg/Kg, a CCR5 antagonist) before CFC training. These rats were not subjected to chronic stress restraint. We evaluated whether CCR5 blockade before CFC training could increase corticosterone, RANTES, or IL-6 levels and affects fear memory consolidation in the rats 24-h post-testing compared with vehicle CFC-trained rats. RESULTS: Elevations of CCR5/RANTES chemokine levels in the hippocampus could have contributed to fear memory consolidation (24 h post-training) and chronic stress restraint did not affect these chemokines in the hippocampus; there were no significant differences in CCR5/RANTES levels between stressed and control rats in the prefrontal cortex (Experiment 1). In Experiment 2, hippocampal CCR5/RANTES levels increased and enhanced fear memory consolidation was observed 12 and 24 h after CFC training sessions with 1 mA of footshock. Increased corticosterone and CCR5/RANTES levels, as well as a higher freezing percentage to the context, were found at 24 h CFC post-testing in maraviroc-treated rats as compared to vehicle-treated animals (experiment-3). Conversely, IL-6 is not affected by maraviroc treatment in CFC training. CONCLUSION: Our findings suggest a role for a hippocampal CCR5/RANTES axis in contextual fear memory consolidation; in fact, RANTES levels increased at 12 and 24 h after CFC training. When CCR5 was blocked by maraviroc before CFC training, RANTES (hippocampus), corticosterone levels, and fear memory consolidation were greater than in vehicle CFC-trained rats 24 h after the CFC session.

Cerebral protection, brain repair, plasticity and cell therapy in ischemic stroke.

Among available treatments in the acute ischemic stroke, only intravenous thrombolysis has been demonstrated to be efficacious. Although the majority of pharmacological neuroprotectants have been efficacious in experimental studies, they have failed in clinical trials. Hence, we need to consider integrated cerebral protection which includes the concept of cerebral repair by supporting cerebral plasticity. We provide a nonsystematic review of the studies published on cerebral protection and repair treatments of cerebral ischemia considering the possibilities of stimulating brain plasticity by trophic factors and cell therapy. The majority of the neuroprotective drugs have failed in clinical trials. Citicoline shows a benefit in meta-analysis and it is currently being explored in a new trial (ICTUS). Neuroprotective drugs combined with reperfusion offer favorable results in experimental animals, but data from clinical studies are not enough. Repair therapies using cerebral plasticity stimulation (trophic factors) and cell therapy have shown certain efficacy in experimental and clinical studies and they are a developing route with clinical therapeutic perspectives.

The Long-Term Algae Extract (Chlorella and Fucus sp) and Aminosulphurate Supplementation Modulate SOD-1 Activity and Decrease Heavy Metals (Hg++, Sn) Levels in Patients with Long-Term Dental Titanium Implants and Amalgam Fillings Restorations.

The toxicity of heavy metals such as Hg++ is a serious risk for human health. We evaluated whether 90 days of nutritional supplementation (d90, n = 16) with Chlorella vulgaris (CV) and Fucus sp extracts in conjunction with aminosulphurate (nutraceuticals) supplementation could detox heavy metal levels in patients with long-term titanium dental implants (average: three, average: 12 years in mouth) and/or amalgam fillings (average: four, average: 15 years) compared to baseline levels (d0: before any supplementation, n = 16) and untreated controls (without dental materials) of similar age (control, n = 21). In this study, we compared levels of several heavy metals/oligoelements in these patients after 90 days (n = 16) of nutritional supplementation with CV and aminozuphrates extract with their own baseline levels (d0, n = 16) and untreated controls (n = 21); 16 patients averaging 44 age years old with long-term dental amalgams and titanium implants for at least 10 years (average: 12 years) were recruited, as well as 21 non-supplemented controls (without dental materials) of similar age. The following heavy metals were quantified in hair samples as index of chronic heavy metal exposure before and after 90 days supplementation using inductively coupled plasma-mass spectrometry (ICP-MS) and expressed as µg/g of hair (Al, Hg++, Ba, Ag, Sb, As, Be, Bi, Cd, Pb, Pt, Tl, Th, U, Ni, Sn, and Ti). We also measured several oligoelements (Ca++, Mg++, Na+, K+, Cu++, Zn++, Mn++, Cr, V, Mo, B, I, P, Se, Sr, P, Co, Fe++, Ge, Rb, and Zr). The algae and nutraceutical supplementation during 90 consecutive days decreased Hg++, Ag, Sn, and Pb at 90 days as compared to baseline levels. The mercury levels at 90 days decreased as compared with the untreated controls. The supplementation contributed to reducing heavy metal levels. There were increased lithium (Li) and germanium (Ge) levels after supplementation in patients with long-term dental titanium implants and amalgams. They also (d90) increased manganesum (Mn++), phosphorum (P), and iron (Fe++) levels as compared with their own basal levels (d0) and the untreated controls. Finally, decreased SuperOxide Dismutase-1 (SOD-1) activity (saliva) was observed after 90 days of supplementation as compared with basal levels (before any supplementation, d0), suggesting antioxidant effects. Conversely, we detected increased SOD-1 activity after 90 days as compared with untreated controls. This SOD-1 regulation could induce antioxidant effects in these patients. The long-term treatment with algae extract and aminosulphurates for 90 consecutive days decreased certain heavy metal levels (Hg++, Ag, Sn, Pb, and U) as compared with basal levels. However, Hg++ and Sn reductions were observed after 90 days as compared with untreated controls (without dental materials). The dental amalgam restoration using activated nasal filters in conjunction with long-term nutritional supplementation enhanced heavy metals removal. Finally, the long-term supplementation with these algae and aminoazuphrates was safe and non-toxic in patients. These supplements prevented certain deficits in oligoelements without affecting their Na+/K+ ratios after long-term nutraceutical supplementation.

Increased Systemic Malondialdehyde Levels and Decreased Mo/Co, Co/Fe2+ Ratios in Patients with Long-Term Dental Titanium Implants and Amalgams.

INTRODUCTION: the biological safety of dental biomaterials has been questioned in human studies. MATERIAL AND METHODS: Several heavy metals/oligoelements were compared by Inductive Coupled Mass Spectrometry (ICP-MS) in hair samples from 130 patients (n = 54 patients with long-term titanium dental implants and amalgams (A + I group), 51 patients with long-term dental amalgam alone (A group), as well as controls (n = 25: without dental materials) of similar age. All patients (except controls) had had titanium dental implants and/or dental amalgams for at least 10 years (average: 17). We evaluated whether A + I patients could present higher systemic malondialdehyde levels (MDA) as compared to the A group. RESULTS: The A + I group have lower molybdenum levels (A + I) and reduced Mo/Co and Mo/Fe2+ ratios, which could predispose them to oxidative stress by raising MDA levels as compared to the A group alone; our findings suggest that higher Co levels could enhance oxidative stress in the A + I group. However, there were no differences on metals from titanium alloy (Ti-6Al), Cr from crowns or Hg2+, Sn, Zn2+, Cu2+ levels between the A + I and A groups. CONCLUSION: patients with long-term dental titanium and amalgams have systemic oxidative stress due to rising MDA levels and lower Mo/Co and Mo/Fe2+ ratios than those with amalgams alone.

Origanum majorana Essential Oil Inhalation during Neurofeedback Training Reduces Saliva Myeloperoxidase Activity at Session-1 in Bruxistic Patients.

Introduction: Bruxism affects teeth and provokes sleep alterations. We evaluated whether saliva Myeloperoxidase (MPO) activity could be reduced after 21 neurofeedback training (NO) sessions in Origanum majorana (AE) bruxistic-treated patients (n = 12 patients, 120 saliva samples). The term divergence evaluates cerebral activity, which was compared between bruxistic patients with/without this essential oil exposure during 21 NO training sessions (n = 12, n = 120 saliva samples). The nasal filter used allow us to vehiculizate this Origanum majorana essential oil in patients. MPO activity was measured in six training NO sessions (Session S1, 6, 12, 18, 21). We included a total of 104 patients and 500 saliva samples. Results: there was a fast reduction in MPO activity after NO session-1 in bruxistic patients; divergence (an index of NO training brain efficacy) is the difference in cerebral activity found between pre-training and post-training levels. Thus, Divergence can fluctuate during NO training before reaching a final calm state after many sessions (21). Repeated NO training lead to habituation in so far as cerebral activity as well as MPO activity after 21 training sessions. Origanum majorana essential oil modulates cerebral activity at certain training sessions in bruxistic patients. Stress levels were reduced on the perceived stress scores (PSS: Cohen Scale) after 21 NO sessions than for those bruxistic without NO training sessions. Conclusions: MPO activity could predict stress level in bruxistic patients and repeated NO reduced their stress level; Origanum majorana essential oil enhanced these anxiolytic effects.

Elevated Systemic L-Kynurenine/L-Tryptophan Ratio and Increased IL-1 Beta and Chemokine (CX3CL1, MCP-1) Proinflammatory Mediators in Patients with Long-Term Titanium Dental Implants.

Titanium is the mean biocompatible metal found in dental titanium alloys (Ti-6Al-4V). The safety of certain dental biomaterial amalgams has been questioned in patients. The levels of several systemic cytokines (interleukin (IL)-1 beta, IL-4: pg/mL) and chemokines (monocyte chemoattractant protein-1 (MCP-1), soluble fractalkine (CX3CL1: pg/mL) were determined using ELISA and compared between these study groups. The study included 30 controls without dental materials (cont), 57 patients with long-term titanium dental implants plus amalgams (A + I group) as well as 55 patients with long-term dental amalgam alone (A group). All patients (except controls) have had dental titanium implants (Ti-6Al-4V) and/or amalgams for at least 10 years (average: 15 years). We evaluated whether systemic levels of cytokines/chemokines, kyn/L-trp ratio and aromatic amino acid levels (HPLC: mM/L, Phe, L-Trp, His, Treo) could be altered in patients with long-term dental titanium and/or amalgams. These systemic markers were evaluated in 142 patients. The A + I group had higher L-Kynurenine/L-Tryptophan ratios than patients with long-term dental amalgam fillings alone (A). In addition, levels of IL-1 Beta cytokine, CX3CL1 and MCP-1 chemokines were higher in the A + I group than in the A group (A). The increased L-kyn/L-trp ratio and MCP-1 and fractalkine receptor (CX3CR1) elevations could suggest enhanced chemotactic responses by these chemokines in the A + I group.

Zirconia implants and peek restorations for the replacement of upper molars.

BACKGROUND: One of the disadvantages of the zirconia implants is the lack of elasticity, which is increased with the use of ceramic or zirconia crowns. The consequences that could result from this lack of elasticity have led to the search for new materials with improved mechanical properties. CASE PRESENTATION: A patient who is a 45-year-old woman, non-smoker and has no medical record of interest with a longitudinal fracture in the palatal root of molar tooth 1.7 and absence of tooth 1.6 was selected in order to receive a zirconia implant with a PEEK-based restoration and a composite coating. The following case report describes and analyses treatment with zirconia implants in molars following a flapless surgical technique. Zirconia implants are an alternative to titanium implants in patients with allergies or who are sensitive to metal alloys. However, one of the disadvantages that they have is their lack of elasticity, which increases with the use of ceramic or zirconia crowns. The consequences that can arise from this lack of elasticity have led to the search for new materials with better mechanical properties to cushion occlusal loads. PEEK-based restoration in implant prosthetics can compensate these occlusal forces, facilitating cushioning while chewing. CONCLUSION: This procedure provides excellent elasticity and resembles natural tooth structure. This clinical case suggests that PEEK restorations can be used in zirconia implants in dentistry.

Effects of CX3CR1 and Fractalkine Chemokines in Amyloid Beta Clearance and p-Tau Accumulation in Alzheimer's Disease (AD) Rodent Models: Is Fractalkine a Systemic Biomarker for AD?

Microglia and astrocytes are the major source of cytokines in Alzheimer,s disease (AD). CX3CR1 is a delta chemokine receptor found in microglia and its neuronal ligand, Fractalkine, has two isoforms: an anchored-membrane isoform, and a soluble isoform. The reduced soluble fractalkine levels found in the brain (cortex/hippocampus) of aged rats, may be a consequence of neuronal loss. This soluble fractalkine maintains microglia in an appropiate state by interacting with CX3CR1. The ablation of the CX3CR1 gene in mice overexpressing human amyloid precursor protein (APP/PS-1) increased cytokine levels, enhanced Tau pathology and worsened behavioural performance in these mice. However, CX3CR1 deficiency resulted in a gene dose-dependent Aß clearance in the brain, and induced microglial activation. In addition, CX3CR1 deficiency can have benefical effects by preventing neuronal loss in the 3xTg model. In fact, CX3CR1 deficiency increases microglial phagocytosome activity by inducing selective protofibrillar amyloid-beta phagocytosis in microglial cells in transgenic AD models. On the other hand, the fractalkine membrane isoform plays a differential role in amyloid beta clearance and Tau deposition. This anchored membrane FKN signalling might increase amyloid pathology while soluble fractalkine levels could prevent taupathies. However, in human AD, the only published study has reported higher systemic fractalkine levels in AD patients with cognitive impairment. In mouse models, inflammatory activation of microglia accelerates Tau pathology. Studies in transgenic mice with fractalkine null mice suggest that APP/PS-1 mice deficient for the anchored membrane-fractalkine isoform exhibited enhanced neuronal MAPT phosphorylation despite their reduced amyloid burden. The soluble fractalkine overexpression with adenoviral vectors reduced tau pathology and prevented neurodegeneration in a Tg4510 model of taupathy Finally, animals with Aß (1-42) infused by lentivirus (cortex) or mice with the P301L mutation (frontotemporal dementia) had caspase-3 activation (8-fold) and higher proinflammatory TNF alpha levels and p-Tau deposits at 4 weeks postinfusion. Thus, the CX3CR1/Fractalkine axis regulates microglial activation, the clearance of amyloid plaque and plays a role in p-Tau intraneuronal accumulation in rodent models of AD.

Brain local and regional neuroglial alterations in Alzheimer's Disease: cell types, responses and implications.

From birth to death, neurons are dynamically accompanied by neuroglial cells in a very close morphological and functional relationship. Three families have been classically considered within the CNS: astroglia, oligodendroglia and microglia. Many types/subtypes (including NGR2+ cells), with a wide variety of physiological and pathological effects on neurons, have been described using morphological and immunocytochemical criteria. Glio-glial, glio-neuronal and neuro-glial cell signaling and gliotransmission are phenomena that are essential to support brain functions. Morphofunctional changes resulting from the plasticity of all the glial cell types parallel the plastic neuronal changes that optimize the functionality of neuronal circuits. Moreover, neuroglia possesses the ability to adopt a reactive status (gliosis) in which, generally, new functions arise to improve and restore if needed the neural functionality. All these features make neuroglial cells elements of paramount importance when attempting to explain any physiological or pathological processes in the CNS, because they are involved in both, neuroprotection/neurorepair and neurodegeneration. There exist diverse and profound, regional and local, neuroglial changes in all involutive processes (physiological and pathological aging; neurodegenerative disorders, including Alzheimer ´s disease -AD-), but today, the exact meaning of such modifications (the modifications of the different neuroglial types, in time and place), is not well understood. In this review we consider the different neuroglial cells and their responses in order to understand the possible role they fulfill in pathogenesis, diagnosis and treatment (preventive or palliative) of AD. The existence of differentiated and/or concurrent pathogenic and neuro-protective/neuro-restorative astroglial and microglial responses is highlighted.

Silicon as neuroprotector or neurotoxic in the human neuroblastoma SH-SY5Y cell line.

Silicon (Si) is a trace element that has been considered to be an environmental contaminant for many years, although different studies have recently reported it is an essential element for living cells. The present study tested the ability of different concentrations of Si G57™ to induce neuroprotection or neurotoxicity over 24 h in the SH-SY5Y human neuroblastoma cell line. Cell viability, cellular proliferation, LDH release, ROS, antioxidant capacity, TBARS, caspase-3, -8 and -9, DNA fragmentation, and TNF-α levels were evaluated. Low Si doses (50-250 ng mL(-1)) increased the cell viability and reduced caspase-3 and -8 activities and TNF-α level. The increase in cell viability was independent of any proliferative effect as there was no variation in cyclin E and PCNA levels. At higher concentrations, Si increased caspase-3, as well as TBARS, LDH, DNA fragmentation, and TNF-α releases. Altogether, these results suggest that Si could act either as a neuroprotector or a neurotoxic agent depending on the concentration tested. This study emphasizes the importance of developing new neuroprotective therapies based on low Si doses.

Increased Zn/Glutathione Levels and Higher Superoxide Dismutase-1 Activity as Biomarkers of Oxidative Stress in Women with Long-Term Dental Amalgam Fillings: Correlation between Mercury/Aluminium Levels (in Hair) and Antioxidant Systems in Plasma.

BACKGROUND: The induction of oxidative stress by Hg can affect antioxidant enzymes. However, epidemiological studies have failed to establish clear association between dental fillings presence and health problems. OBJECTIVES: To determine whether heavy metals (in hair), antioxidant enzymes (SOD-1) and glutathione levels could be affected by the chronic presence of heavy metals in women who had dental amalgam fillings. MATERIALS AND METHODS: 55 hair samples (42 females with amalgam fillings and 13 female control subjects) were obtained. All subjects (mean age 44 years) who had dental amalgam filling for more than 10 years (average 15 years). Certain metals were quantified by ICP-MS (Mass Spectrophotometry) in hair (µg/g: Al, Hg, Ba, Ag, Sb, As, Be, Bi, Cd, Pb, Pt, Tl, Th, U, Ni, Sn, Ti) and SOD-1 and Glutathione (reduced form) levels in plasma. Data were compared with controls without amalgams, and analyzed to identify any significant relation between metals and the total number of amalgam fillings, comparing those with four or less (n = 27) with those with more than four (n = 15). As no significant differences were detected, the two groups were pooled (Amlgam; n = 42). FINDINGS: Hg, Ag, Al and Ba were higher in the amalgam group but without significant differences for most of the heavy metals analyzed. Increased SOD-1 activity and glutathione levels (reduced form) were observed in the amalgam group. Aluminum (Al) correlated with glutathione levels while Hg levels correlated with SOD-1. The observed Al/glutathione and Hg/SOD-1 correlation could be adaptive responses against the chronic presence of mercury. CONCLUSIONS: Hg, Ag, Al and Ba levels increased in women who had dental amalgam fillings for long periods. Al correlated with glutathione, and Hg with SOD-1. SOD-1 may be a possible biomarker for assessing chronic Hg toxicity.

The nitric oxide donor SNAP-induced amino acid neurotransmitter release in cortical neurons. Effects of blockers of voltage-dependent sodium and calcium channels.

BACKGROUND: The discovery that nitric oxide (NO) functions as a signalling molecule in the nervous system has radically changed the concept of neuronal communication. NO induces the release of amino acid neurotransmitters but the underlying mechanisms remain to be elucidated. FINDINGS: The aim of this work was to study the effect of NO on amino acid neurotransmitter release (Asp, Glu, Gly and GABA) in cortical neurons as well as the mechanism underlying the release of these neurotransmitters. Cortical neurons were stimulated with SNAP, a NO donor, and the release of different amino acid neurotransmitters was measured by HPLC. The involvement of voltage dependent Na+ and Ca2+ channels as well as cGMP in its mechanism of action was evaluated. CONCLUSIONS: Our results indicate that NO induces release of aspartate, glutamate, glycine and GABA in cortical neurons and that this release is inhibited by ODQ, an inhibitor of soluble guanylate cyclase. Thus, the NO effect on amino acid neurotransmission could be mediated by cGMP formation in cortical neurons. Our data also demonstrate that the Na+ and Ca2+ voltage- dependent calcium channels are involved in the NO effects on cortical neurons.