Chemical Blocking of Zinc Ions in CNS Increases Neuronal Damage Following Traumatic Brain Injury (TBI) in Mice

Traumatic brain injury (TBI) is one of the leading causes of disability and death among young people. Although much is already known about secondary brain damage the full range of brain tissue responses to TBI remains to be elucidated. A population of neurons located in cerebral areas associated with higher cognitive functions harbours a vesicular zinc pool co-localized with glutamate. This zinc enriched pool of synaptic vesicles has been hypothesized to take part in the injurious signalling cascade that follows pathological conditions such as seizures, ischemia and traumatic brain injury. Pathological release of excess zinc ions from pre-synaptic vesicles has been suggested to mediate cell damage/death to postsynaptic neurons.In order to substantiate the influence of vesicular zinc ions on TBI, we designed a study in which damage and zinc movements were analysed in several different ways. Twenty-four hours after TBI ZnT3-KO mice (mice without vesicular zinc) were compared to littermate Wild Type (WT) mice (mice with vesicular zinc) with regard to histopathology. Furthermore, in order to evaluate a possible neuro-protective dimension of chemical blocking of vesicular zinc, we treated lesioned mice with either DEDTC or selenite. Our study revealed that chemical blocking of vesicular zinc ions, either by chelation with DEDTC or accumulation in zinc-selenium nanocrystals, worsened the effects on the aftermath of TBI in the WT mice by increasing the number of necrotic and apoptotic cells within the first 24 hours after TBI, when compared to those of chemically untreated WT mice.ZnT3-KO mice revealed more damage after TBI compared to WT controls. Following treatment with DEDTC or selenium an increase in the number of both dead and apoptotic cells were seen in the controls within the first 24 hours after TBI while the degree of damage in the ZnT3-KO mice remained largely unchanged. Further analyses revealed that the damage development in the two mouse strains was almost identical after either zinc chelation or zinc complexion therapy

Kupffer cells are central in the removal of nanoparticles from the organism

<p>Abstract</p> <p>Background</p> <p>The study aims at revealing the fate of nanoparticles administered intravenously and intraperitoneally to adult female mice, some of which were pregnant. Gold nanoparticles were chosen as a model because these particles have been found to be chemically inert and at the same time are easily traced by autometallography (AMG) at both ultrastructural and light microscopic levels.</p> <p>Results</p> <p>Gold nanoparticles were injected intravenously (IV) or intraperitoneally (IP) and traced after 1, 4 or 24 hours. For IV injections 2 and 40 nm particles were used; for IP injections 40 nm particles only. The injected nanoparticles were found in macrophages only, and at moderate exposure primarily in the Kupffer cells in the liver. IV injections resulted in a rapid accumulation/clustering of nanoparticles in these liver macrophages, while the uptake in spleen macrophages was moderate. IP injections were followed by a delayed uptake in the liver and included a moderate uptake in macrophages located in mesenteric lymph nodes, spleen and small intestine. Ultrastructurally, the AMG silver enhanced nanocrystals were found in lysosome-like organelles of the Kupffer cells and other macrophages wherever located.</p> <p>Accumulations of gold nanoparticles were not found in any other organs analysed, i.e. kidneys, brain, lungs, adrenals, ovaries, placenta, and fetal liver, and the control animals were all void of AMG staining.</p> <p>Conclusion</p> <p>Our results suggest that: (1) inert gold nanoparticles do not penetrate cell membranes by non-endocytotic mechanisms, but are rather taken up by endocytosis; (2) gold nanoparticles, independent of size, are taken up primarily by Kupffer cells in the liver and secondarily by macrophages in other places; (3) gold nanoparticles do not seem to penetrate the placenta barrier; (4) the blood-brain barrier seems to protect the central nervous system from gold nanoparticles; (5) 2 nanometer gold particles seem to be removed not only by endocytosis by macrophages, and we hypothesize that part of these tiny nanoparticles are released into the urine as a result of simple filtration in the renal glomeruli.</p

SLC30A3 Responds to Glucose- and Zinc Variations in ß-Cells and Is Critical for Insulin Production and In Vivo Glucose-Metabolism During ß-Cell Stress

BACKGROUND:Ion transporters of the Slc30A- (ZnT-) family regulate zinc fluxes into sub-cellular compartments. beta-cells depend on zinc for both insulin crystallization and regulation of cell mass. METHODOLOGY/PRINCIPAL FINDINGS:This study examined: the effect of glucose and zinc chelation on ZnT gene and protein levels and apoptosis in beta-cells and pancreatic islets, the effects of ZnT-3 knock-down on insulin secretion in a beta-cell line and ZnT-3 knock-out on glucose metabolism in mice during streptozotocin-induced beta-cell stress. In INS-1E cells 2 mM glucose down-regulated ZnT-3 and up-regulated ZnT-5 expression relative to 5 mM. 16 mM glucose increased ZnT-3 and decreased ZnT-8 expression. Zinc chelation by DEDTC lowered INS-1E insulin content and insulin expression. Furthermore, zinc depletion increased ZnT-3- and decreased ZnT-8 gene expression whereas the amount of ZnT-3 protein in the cells was decreased. Zinc depletion and high glucose induced apoptosis and necrosis in INS-1E cells. The most responsive zinc transporter, ZnT-3, was investigated further; by immunohistochemistry and western blotting ZnT-3 was demonstrated in INS-1E cells. 44% knock-down of ZnT-3 by siRNA transfection in INS-1E cells decreased insulin expression and secretion. Streptozotocin-treated mice had higher glucose levels after ZnT-3 knock-out, particularly in overt diabetic animals. CONCLUSION/SIGNIFICANCE:Zinc transporting proteins in beta-cells respond to variations in glucose and zinc levels. ZnT-3, which is pivotal in the development of cellular changes as also seen in type 2 diabetes (e.g. amyloidosis in Alzheimer's disease) but not previously described in beta-cells, is present in this cell type, up-regulated by glucose in a concentration dependent manner and up-regulated by zinc depletion which by contrast decreased ZnT-3 protein levels. Knock-down of the ZnT-3 gene lowers insulin secretion in vitro and affects in vivo glucose metabolism after streptozotocin treatment

Biodistribution of gold nanoparticles in mouse lung following intratracheal instillation

<p>Abstract</p> <p>Background</p> <p>The fate of gold nanoparticles, 2, 40 and 100 nm, administered intratracheally to adult female mice was examined. The nanoparticles were traced by autometallography (AMG) at both ultrastructural and light microscopic levels. Also, the gold content was quantified by inductively coupled plasma mass spectrometry (ICP-MS) and neutron activation analysis (NAA). The liver is the major site of deposition of circulating gold nanoparticles. Therefore the degree of translocation was determined by the hepatic deposition of gold. Mice were instilled with 5 intratracheal doses of gold nanoparticles distributed over a period of 3 weeks and were killed 24 h after the last dose. One group of mice were given a single intratracheal dose and were killed after 1 h.</p> <p>Results</p> <p>The instilled nanoparticles were found in lung macrophages already 1 h after a single instillation. In mice instilled treated repeatedly during 3 weeks, the load was substantial. Ultrastructurally, AMG silver enhanced gold nanoparticles were found in lysosome-/endosome-like organelles of the macrophages and analysis with AMG, ICP-MS and NAA of the liver revealed an almost total lack of translocation of nanoparticles. In mice given repeated instillations of 2 nm gold nanoparticles, 1.4‰ (by ICP-MS) to 1.9‰ (by NAA) of the instilled gold was detected in the liver. With the 40 nm gold, no gold was detected in the liver (detection level 2 ng, 0.1‰) except for one mouse in which 3‰ of the instilled gold was found in the liver. No gold was detected in any liver of mice instilled with 100 nm gold (detection level 2 ng, 0.1‰) except in a single animal with 0.39‰ of the dose in the liver.</p> <p>Conclusion</p> <p>We found that that: (1) inert gold nanoparticles, administered intratracheally are phagocytosed by lung macrophages; (2) only a tiny fraction of the gold particles is translocated into systemic circulation. (3) The translocation rate was greatest with the 2 nm gold particles.</p

Cultured macrophages cause dissolucytosis of metallic silver

The present study proves that cultured macrophages can liberate silver ions from metallic silver surfaces by a process called dissolucytosis. Macrophages (J774) were grown on a silver plate for different periods of time and after fixation in glutaraldehyde, they were subjected to autometallograhy in order to amplify possible cellular silver-sulphur nanocrystals. Light and electron microscopic analysis of the cells revealed that silver ions released from the plate had been taken up by the macrophages and accumulated in lysosome- like structures. We found that the liberation of silver ions takes place extracellularly and is caused by chemical activity in a dissolution membrane, most likely secreted and organized by the macrophages. The liberation and the subsequent uptake of silver ions in the macrophages is a relatively fast process and the resulting silver-sulphur nanocrystals can be observed in macrophages that have been in contact with metallic silver for only a few minutes. Our findings indicate that the speed of dissolucytosis is highly influenced by the chemical nature of the object exposed to the dissolucytotic process which is likely to occur whenever macrophages encounter a non-phagocytosable foreign object

Uptake of silver from metallic silver surfaces induces cell death and a pro-inflammatory response in cultured J774 macrophages

In clinical medicine metallic silver is used as anti-bacterial coating on various catheters, bandages and prostheses. By means of dissolucytosis, i.e. extracellular macrophage-mediated bio-liberation of metal ions, silver ions are continuously liberated from silver surfaces starting within minutes of exposure. The present study investigates how bio-liberation and subsequent cellular uptake of silver ions affects cell viability and cell signalling within the first 3-24 hours of exposure when J774 macrophages are grown directly on a silver surface. Autometallography (AMG) was applied to demonstrate cytoplasmatic silver uptake and localisation after 1, 3, 12 and 24 hours of exposure to metallic silver. From 12 hours onwards the cells were completely filled with silver enhanced silver-sulphur nanocrystals (AMG-silver grains). At the ultrastructural level, the silver accumulations were located to lysosome-like structures. An immunoassay cell death kit found silver-induced apoptosis after 12 and 24 hours of exposure. Necrosis was seen at the same times. Judged by mRNA analysis silver exposure statistically significantly induces TNF-α and m-CSF gene expression, especially at 3 hours. Furthermore, anti-inflammatory IL-10 transcription is reduced by silver uptake and 24 hours of silver exposure induces massive iNOS-2 gene expression. At the same time silver exposure increases the gene expression of metallothionein (MT-I/MT-II), a cystein-rich protein known for its role in detoxifying heavy metals. Our data suggest that silver ions liberated from metallic silver surfaces accumulate in lysosomes, reduce macrophage viability by apoptosis and necrosis and induce a proinflammatory response

Metallic gold treatment reduces proliferation of inflammatory cells, increases expression of VEGF and FGF, and stimulates cell proliferation in the subventricular zone following experimental traumatic brain injury

Traumatic brain injury represents a leading cause of morbidity in young individuals and there is an imperative need for neuroprotective treatments limiting the neurologic impairment following such injury. It has recently been demonstrated that bio-liberated gold ions liberated from small metallic gold implants reduce inflammation and neuronal apoptosis, while generating an increased neuronal stem cell response following focal brain damage. In this study mice were subjected to a unilateral traumatic cryo-lesion with concomitant injection of 25-45 μm gold particles near the lesion. Placebo-treated mice subjected to cryo-lesion served as controls. The effects of gold-treatment were investigated by examining gold-induced growth factor expression (VEGF and FGF) in the first two weeks after the insult, and the extent of the neurostimulatory effect of gold was explored by comparing cell proliferation in the subventricular zone as judged by immunohistochemical staining for CDC47. Vimentin staining revealed a decrease in activated microglia and a transient astrogliosis in response to the gold liberation. Moreover, gold ions significantly increase the expression of VEGF and FGF following trauma and a significant increase in cell proliferation in both the ipsilateral and the contralateral subventricular zone was found in response to gold-treatment. In conclusion: we confirmed the previously demonstrated anti-inflammatory effect of bioliberated gold ions, and further show that metallic gold increases growth factor expression and adult neurogenesis