Name: toxicity study of zinc oxide nanoparticles in cell culture and in drosophila melanogaster
Uploaded: 2019-09-19T13:30:00
Description: Watch this Scientific Journal Video about Toxicity Study of Zinc Oxide Nanoparticles in Cell Culture and in Drosophila melanogaster at JoVE.com

The study was supported by the grant number R706-000-043-490. The study does not represent the view of the grant sponsor.

1. Fluorescence Activated Cell Sorting (FACS) Analysis on Lived/Fixed cells
<ol>
	<li>Sonicate ZnO NPs in suspension for 15 min.</li>
	<li>Prepare ZnO NPs at various concentrations (e.g., 0, 10, 25, 50,100 and 200 &#181;g/mL) using 1 mg/mL ZnO NP stock solution for the treatment of cultured cells.</li>
	<li>Seed MRC5 human lung fibroblasts (1 x 105 cells/well) onto a 6-well culture plate a day in advance, and then treat the cells with 2 mL of ZnO NPs (in triplicates) for 8 h, 16 h, and 24 h.</li>
	<li>At eac...

<ol>
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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophotoxicology:+the+growing+potential+for+Drosophila+in+neurotoxicology.">Drosophotoxicology: the growing potential for Drosophila in neurotoxicology.</a> Neurotoxicology and Teratology. 32, 74-83 (2010).</li><li>Ong, C., Yung, L. Y., Cai, Y., Bay, B. H., Baeg, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila+melanogaster+as+a+model+organism+to+study+nanotoxicity.">Drosophila melanogaster as a model organism to study nanotoxicity.</a> Nanotoxicology. 9, 396-403 (2015).</li><li>Hoffmann, J. A., Reichhart, J. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+sequence+to+phenotype:+reverse+genetics+in+Drosophila+melanogaster.">From sequence to phenotype: reverse genetics in Drosophila melanogaster.</a> Nature Reviews Genetics. 3, 189-198 (2002).</li><li>Adams, M. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+genome+sequence+of+Drosophila+melanogaster.">The genome sequence of Drosophila melanogaster.</a> Science. 287, 2185-2195 (2000).</li><li>Ong, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silver+nanoparticles+disrupt+germline+stem+cell+maintenance+in+the+Drosophila+testis.">Silver nanoparticles disrupt germline stem cell maintenance in the Drosophila testis.</a> Scientific Reports. 6, (2016).</li><li>Alaraby, M., Demir, E., Hernandez, A., Marcos, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+potential+harmful+effects+of+CdSe+quantum+dots+by+using+Drosophila+melanogaster+as+in+vivo+model.">Assessing potential harmful effects of CdSe quantum dots by using Drosophila melanogaster as in vivo model.</a> Science of the Total Environment. 530-531, 66-75 (2015).</li><li>Barik, B. K., Mishra, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticles+as+a+potential+teratogen:+a+lesson+learnt+from+fruit+fly.">Nanoparticles as a potential teratogen: a lesson learnt from fruit fly.</a> Nanotoxicology. , 1-27 (2018).</li><li>Jovanovic, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+a+human+food+additive,+titanium+dioxide+nanoparticles+E171,+on+Drosophila+melanogaster+-+a+20+generation+dietary+exposure+experiment.">The effects of a human food additive, titanium dioxide nanoparticles E171, on Drosophila melanogaster - a 20 generation dietary exposure experiment.</a> Scientific Reports. 8, (2018).</li><li>Cao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Toxicity+of+Nanoparticles+to+Human+Endothelial+Cells.">The Toxicity of Nanoparticles to Human Endothelial Cells.</a> Advances in Experimental Medicine and Biology. 1048, 59-69 (2018).</li><li>Akhtar, M. 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In order to assess if ZnO NP can induce apoptosis in MRC5 fibroblasts, we use flow cytometry to distinguish the cells from necrotic or apoptotic cell death. In normal live cells, phosphatidylserine (PS) is localized at the cell membrane. If apoptosis occurs, PS is translocated to the extracellular leaflet of the plasma membrane, allowing the binding of Annexin V labeled with fluorescein (FITC Annexin V)29. On the other hand, the red-fluorescent propidium iodide (PI), a nucleic acid binding dye, is...

Nanotechnology refers to the application of nanosized materials that are used across all scientific fields, including medicine, materials science, and biochemistry. For instance, ZnO NPs which are known for their ultraviolet scattering, chemical sensing, and anti-microbial properties, as well as high electrical conductivity, are utilized in the production of various consumer products such as food packaging, cosmetics, textiles, rubbers, batteries, catalyst for automobile tail gas treatment, and biomedical-related applications1,2,3.
However, the burgeoning applications of ZnO NP-based products, leading to increased human exposure to ZnO NPs, have raised concerns on their potential adverse effects on human health. A number of in vitro cellular studies have demonstrated that ZnO NPs can induce oxidative stress, autophagy-related cytotoxicity, inflammation, and genotoxicity4,5,6,7,8. Notably, the toxicity of ZnO NPs is assumed to be caused by the dissolution of Zn to free Zn2+ ions, as well as the surface reactivity of ZnO, resulting in the cellular ionic and metabolic imbalances that are linked with impaired ionic homeostasis and an inhibition of ion transportation4,7,9,10. Importantly, studies have shown that the generation of reactive oxygen species (ROS) is one of the primary mechanisms underlying ZnO NPs-associated toxicity. Insufficient anti-oxidative activity following ROS insult has been shown to be responsible for eliciting the cytotoxicity and DNA damage9. The toxic effects of ZnO NPs have also been reported in animal models, including rodent1, zebrafish11,12, as well as the invertebrate Drosophila13.
Drosophila serves as a well-established alternative animal model for toxicity screening of chemical entities and nanomaterials (NMs)14,15. Importantly, there are high levels of genetic and physiological similarity between human and Drosophila that justifies the use of Drosophila as an in vivo model for evaluating biological responses to environmental contaminants such as NMs16. Furthermore, there are many advantages of using Drosophila due to its small size, short lifespan, genetic amenability, and easy and cost-effective maintenance. Moreover, Drosophila has been widely adopted for the study of genetics, molecular and developmental biology, ever since its full genome was fully sequenced years ago back in 2000, therefore making it suitable for a variety of high-throughput screening and for tackling unresolved biological questions17,18,19,20,21. In recent years, a number of studies related to immunotoxicity using different types of NPs in Drosophila have been reported15,22,23,24. This fundamental new knowledge obtained from the studies using Drosophila has helped to provide more insights into our understanding of nanotoxicology.
ROS is a well-known culprit for cytotoxicity and genotoxicity caused by NPs, in particular, metal-based NPs25. ROS are oxygen-containing chemical species with higher reactive properties than molecular oxygen. Free radicals such as superoxide radical (O2-) and even, non-radical molecules such as hydrogen peroxide (H2O2) can act as ROS. Under normal physiological condition, they are required to maintain cellular homeostasis26, however, excessive ROS due to overproduction or dysregulation of the antioxidant defense system can cause oxidative stress, leading to damage to proteins, lipids and deoxyribonucleic acid (DNA)27. For instance, as ROS levels increase and glutathione (GSH) level decreases concomitantly, disruption of adenosine triphosphate (ATP) synthesis takes place and lactate dehydrogenase (LDH) level increases in the medium, culminating in cell death27.
Here, we provide protocols for performing cellular and genetic analyses using cultured mammalian cells and Drosophila to determine the potential adverse effects of ZnO NPs. An overview of the method used for the toxicity study of ZnO NPs is shown in Figure 1.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>15% Methyl 4-Hydroxybenzoate</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4% Paraformaldehyde</td>
			<td>Sigma Aldrich</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr>
			<td>Bacto Agar</td>
			<td>BD biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>cncCK6/TM3, Sb</td>
			<td></td>
			<td></td>
			<td>a gift from Dr. Kerppola T</td>
		</tr>
		<tr>
			<td>cornmeal, glucose, yeast brewer</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CyAn ADP with Summit Software</td>
			<td>DAKO</td>
			<td></td>
			<td>https://flow.usc.edu/files/2014/07/BC-Cyan-ADP-User-Guide-2016.pdf</td>
		</tr>
		<tr>
			<td>Dihydroethidium (Hydroethidine)</td>
			<td>Thermo Fisher Scientific</td>
			<td>D11347</td>
			<td></td>
		</tr>
		<tr>
			<td>FITC Annexin V Apoptosis Detection Kit I</td>
			<td>BD biosciences</td>
			<td>556547</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent microscope</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Glucolin</td>
			<td>Supermarket</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Image J software</td>
			<td>NIH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MRC5 human lung fibroblast</td>
			<td>ATCC</td>
			<td>CCL-171</td>
			<td></td>
		</tr>
		<tr>
			<td>Schneider&#8217;s Drosophila medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>21720-024</td>
			<td></td>
		</tr>
		<tr>
			<td>vectashield antifade mounting medium with DAPI</td>
			<td>Vector Laboratories</td>
			<td>H-1200</td>
			<td></td>
		</tr>
		<tr>
			<td>wild- type Canton-S; Sod2N308/CyO</td>
			<td>NIG-FLY</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zinc Oxide Nanoparticles</td>
			<td>Sigma Aldrich</td>
			<td>721077</td>
			<td>Refer Sheet 2</td>
		</tr>
	</tbody>
</table>

toxicity study of zinc oxide nanoparticles in cell culture and in drosophila melanogaster

Zinc oxide nanoparticles (ZnO NPs) have a wide range of applications, but the number of reports on ZnO NP-associated toxicity has grown rapidly in recent years. However, studies that elucidate the underlying mechanisms for ZnO NP-induced toxicity are scanty. We determined the toxicity profiles of ZnO NPs using both in vitro and in vivo experimental models. A significant decrease in cell viability was observed in ZnO NP-exposed MRC5 lung fibroblasts, showing that ZnO NPs exert cytotoxic effects. Similarly, interestingly, gut exposed to ZnO NPs exhibited a dramatic increase in reactive oxygen species levels (ROS) in the fruit fly Drosophila. More in-depth studies are required to establish a risk assessment for the increased usage of ZnO NPs by consumers.

NP-exposed cells were processed with the cell staining reagent kit, followed by cell sorting using flow cytometry. ZnO NP-treated cells (bottom, right panel) exhibit a higher percentage of early (R3)/ late apoptotic cells (R6) than control cells (R5, bottom, left panel). Necrotic cell death is denoted by R4 (top, right panel) (Figure 2). The results of the FITC/Annexin V Assay on ZnO NP-treated MRC-5 fibroblasts are shown in Figure 2</str...

Watch this Scientific Journal Video about Toxicity Study of Zinc Oxide Nanoparticles in Cell Culture and in Drosophila melanogaster at JoVE.com

Toxicity Study of Zinc Oxide Nanoparticles in Cell Culture and in Drosophila melanogaster

We describe a detailed protocol for evaluating the toxicological profiles of zinc oxide nanoparticles (ZnO NPs) in particular, the type of cell death in human MRC5 lung fibroblasts and ROS formation in the fruit fly Drosophila.

Toxicity Study of Zinc Oxide Nanoparticles in Cell Culture and in Drosophila melanogaster

Zinc oxide nanoparticles (ZnO NPs) have a wide range of applications, but the number of reports on ZnO NP-associated toxicity has grown rapidly in recent ...

Our methods outline a simple and repeat way for studying nanotoxicity, such as examining the types of cell death and examining the production of reactive oxygen species. Fluorescence activated cell sorting is a strict format that allows us to study the subpopulation of cells and the growing different types of cell death. The DHE probe study method allows us to detect and quantify reactive oxygen species followed by flow cytometry, microscopic high-content imaging, and by couplet based fluorescence analysis.To begin, place an Eppendorf tube containing zinc oxide nanoparticles in zinc oxide nanoparticle stock solution into a sonicator for 15 minutes. Prepare zinc oxide nanoparticles at various concentrations using one-milligram-per-milliliter zinc oxide nanoparticle stock. Then, in a biosafety cabinet, seed MRC5 human lung fibroblasts onto three six-well culture plates at the concentration of one times 10 to the fifth cells per well.Incubate the cells at 37 degrees Celsius. After one day, treat the cells with two milliliters of zinc oxide nanoparticles for eight hours, 16 hours, or 24 hours. At each time point, collect the cells into a 15-milliliter centrifuge tube, and centrifuge at 300 times g for five minutes.Wash the cell pellets twice with phosphate-buffered saline, and then resuspend the cells with 1X binding buffer. Next, add five microliters of FITC Annexin V stain in five microliters of propidium iodide DNA stain. Incubate the stained cells for 15 minutes at room temperature in the dark.Before sorting the cells by flow cytometry, top up the samples with an additional 400 microliters of 1X binding buffer. Tabulate the bar chart using the median intensity obtained. Now use a pipette to add one milliliter of nanoparticles at different concentrations into vials, followed by nine milliliters of fly food to make a final concentration of 0.1 milligrams per milliliter, 0.25 milligrams per milliliter, or 0.5 milligrams per milliliter zinc oxide nanoparticles.Pipette up and down to mix thoroughly. Allow fly food containing zinc oxide nanoparticles to cool for at least two to three hours before use. Then anesthetize adult male and female flies in a vial with carbon dioxide, and introduce five male flies and five female flies into each vial for five days.Allow them to mate and lay eggs on the surface of the food. After anesthetization, remove the parental flies and allow the eggs to undergo further development at room temperature, which consists of four different developmental stages. Embryonic, larval, pupal, and adult stage.After 72 to 120 hours, freshly-laid eggs develop into late third instar larvae. Using forceps, collect the larvae from the wall of the vials for analyses. In a well of a dissection dish with dissection medium or PBS, place the larvae into the solution.Under the stereomicroscope, use the tip of the forceps to make a tiny hole, and break open the cuticle layer of the larvae. Carefully pull out the gut. Place the gut into a 1.5-milliliter microcentrifuge tube containing Schneider's Drosophila Medium.Add one microliter of the DHE probe, and incubate in the dark at room temperature for 10 minutes. Wash the gut three times using Schneider's Medium every five minutes. Mount the gut onto glass slides, and supply with 10 microliters of antifade mounting medium containing DAPI.Capture images under a confocal microscope. To measure fluorescence, import the captured fluorescence images acquired using fluorescence microscopy or confocal laser scanning microscopy into the ImageJ software. Click on the analyze menu, and select set measurements.Select the output measure, such as area integrated intensity and mean gray value. Select a region without fluorescence to set the background. Click measure.Export the data into the spreadsheet, and determine the corrected total cell fluorescence. Construct a bar chart, and perform statistical analysis. In this study, zinc oxide nanoparticle-treated cells exhibit a higher percentage of early R3 or late apoptotic R6 cells than control cells R5.Necrotic cell death was denoted by R4.The gut extracted from the drosophila larva was divided into three discrete domains of different developmental origin.Namely, the foregut, midgut, and hindgut. DHE stock tends to expire rather quickly, so be careful of the stock solution you are using. Alternatively, you could try other probes, for example cell Roche, which is designed to detect the intracellular ROS in green signals, and that is more photostable than the DHE.Our protocol provides a general outline for studying the intracellular ROS production, and quantification of ROS level for nanotoxicity study. DMSO is known to be a better solvent for DHE than the PBS. However, DMSO is toxic.Therefore, I would like to advise the user to restrict the entire process for studying to 30 minutes maximum. This is because you may observe a false positive outcome as DMSO may cause cell death.

toxicity-study-zinc-oxide-nanoparticles-cell-culture-drosophila

Research

JoVE Journal

Immunology and Infection

Retroviral Transduction of T-cell Receptors in Mouse T-cells

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen presenting cells (APCs)1. This recognition leads to the activation of T-cells and a series of functional outcomes (e.g. cytokine production, killing of the target cells). Understanding the functional role of TCRs is critical to harness the power of the immune system to treat a variety of immunology related diseases (e.g. cancer or autoimmunity).
It is convenient to study TCRs in mouse models, which can be accomplished in several ways. Making TCR transgenic mouse models is costly and time-consuming and currently there are only a limited number of them available2-4. Alternatively, mice with antigen-specific T-cells can be generated by bone marrow chimera. This method also takes several weeks and requires expertise5. Retroviral transduction of TCRs into in vitro activated mouse T-cells is a quick and relatively easy method to obtain T-cells of desired peptide-MHC specificity. Antigen-specific T-cells can be generated in one week and used in any downstream applications. Studying transduced T-cells also has direct application to human immunotherapy, as adoptive transfer of human T-cells transduced with antigen-specific TCRs is an emerging strategy for cancer treatment6.
Here we present a protocol to retrovirally transduce TCRs into in vitro activated mouse T-cells. Both human and mouse TCR genes can be used. Retroviruses carrying specific TCR genes are generated and used to infect mouse T-cells activated with anti-CD3 and anti-CD28 antibodies. After in vitro expansion, transduced T-cells are analyzed by flow cytometry.

We present a protocol to produce antigen-specific mouse T-cells using retroviral transduction

T-cell receptors (TCRs) play a central role in the immune system. TCRs on T-cell surfaces can specifically recognize peptide antigens presented by antigen ...

Novel Whole-tissue Quantitative Assay of Nitric Oxide Levels in Drosophila Neuroinflammatory Response

Neuroinflammation is a complex innate immune response vital to the healthy function of the central nervous system (CNS). Under normal conditions, an intricate network of inducers, detectors, and activators rapidly responds to neuron damage, infection or other immune infractions. This inflammation of immune cells is intimately associated with the pathology of neurodegenerative disorders, such as Parkinson&#39;s disease (PD), Alzheimer&#39;s disease and ALS. Under compromised disease states, chronic inflammation, intended to minimize neuron damage, may lead to an over-excitation of the immune cells, ultimately resulting in the exacerbation of disease progression. For example, loss of dopaminergic neurons in the midbrain, a hallmark of PD, is accelerated by the excessive activation of the inflammatory response. Though the cause of PD is largely unknown, exposure to environmental toxins has been implicated in the onset of sporadic cases. The herbicide paraquat, for example, has been shown to induce Parkinsonian-like pathology in several animal models, including Drosophila melanogaster. Here, we have used the conserved innate immune response in Drosophila to develop an assay capable of detecting varying levels of nitric oxide, a cell-signaling molecule critical to the activation of the inflammatory response cascade and targeted neuron death. Using paraquat-induced neuronal damage, we assess the impact of these immune insults on neuroinflammatory stimulation through the use of a novel, quantitative assay. Whole brains are fully extracted from flies either exposed to neurotoxins or of genotypes that elevate susceptibility to neurodegeneration then incubated in cell-culture media. Then, using the principles of the Griess reagent reaction, we are able to detect minor changes in the secretion of nitric oxide into cell-culture media, essentially creating a primary live-tissue model in a simple procedure. The utility of this model is amplified by the robust genetic and molecular complexity of Drosophila melanogaster, and this assay can be modified to be applicable to other Drosophila tissues or even other small, whole-organism inflammation models.

Novel Whole-tissue Quantitative Assay of Nitric Oxide Levels in Drosophila Neuroinflammatory Response

Levels of the inflammatory cell-signaling molecule nitric oxide (NO) are commonly assayed using Griess reagent. In this protocol, we have created a modified Griess assay utilizing live Drosophila brain tissue in order to detect the secretion of NO in a simple, quantifiable and highly repeatable method.

Neuroinflammation is a complex innate immune response vital to the healthy function of the central nervous system (CNS). Under normal conditions, an ...

Systemic Bacterial Infection and Immune Defense Phenotypes in Drosophila Melanogaster

The fruit fly Drosophila melanogaster is one of the premier model organisms for studying the function and evolution of immune defense. Many aspects of innate immunity are conserved between insects and mammals, and since Drosophila can readily be genetically and experimentally manipulated, they are powerful for studying immune system function and the physiological consequences of disease. The procedure demonstrated here allows infection of flies by introduction of bacteria directly into the body cavity, bypassing epithelial barriers and more passive forms of defense and allowing focus on systemic infection. The procedure includes protocols for the measuring rates of host mortality, systemic pathogen load, and degree of induction of the host immune system. This infection procedure is inexpensive, robust and quantitatively repeatable, and can be used in studies of functional genetics, evolutionary life history, and physiology.

Systemic Bacterial Infection and Immune Defense Phenotypes in Drosophila Melanogaster

Drosophila melanogaster is an outstanding model organism for studying innate immune systems and the physiological consequences of infection and disease. This protocol describes how to deliver robust and quantitatively repeatable bacterial infections to D. melanogaster, and how to subsequently measure infection severity and quantify the host immune response.

The fruit fly Drosophila melanogaster is one of the premier model organisms for studying the function and evolution of immune defense. Many aspects of ...

Kupffer Cell Isolation for Nanoparticle Toxicity Testing

The large majority of in vitro nanotoxicological studies have used immortalized cell lines for their practicality. However, results from nanoparticle toxicity testing in immortalized cell lines or primary cells have shown discrepancies, highlighting the need to extend the use of primary cells for in vitro assays. This protocol describes the isolation of mouse liver macrophages, named Kupffer cells, and their use to study nanoparticle toxicity. Kupffer cells are the most abundant macrophage population in the body and constitute part of the reticulo-endothelial system (RES), responsible for the capture of circulating nanoparticles. The Kupffer cell isolation method reported here is based on a 2-step perfusion method followed by purification on density gradient. The method, based on collagenase digestion and density centrifugation, is adapted from the original protocol developed by Smedsr&#248;d et al. designed for rat liver cell isolation and provides high yield (up to 14 x 106 cells per mouse) and high purity (&#62;95%) of Kupffer cells. This isolation method does not require sophisticated or expensive equipment and therefore represents an ideal compromise between complexity and cell yield. The use of heavier mice (35-45 g) improves the yield of the isolation method but also facilitates remarkably the procedure of portal vein cannulation. The toxicity of functionalized carbon nanotubes f-CNTs was measured in this model by the modified LDH assay. This method assesses cell viability by measuring the lack of structural integrity of Kupffer cell membrane after incubation with f-CNTs. Toxicity induced by f-CNTs can be measured consistently using this assay, highlighting that isolated Kupffer cells are useful for nanoparticle toxicity testing. The overall understanding of nanotoxicology could benefit from such models, making the nanoparticle selection for clinical translation more efficient.

Liver macrophages, named Kupffer cells, are responsible for the capture of circulating nanoparticles. We describe here a method, of high cell purity and yield, for Kupffer cell isolation. The modified LDH assay is used here to measure the toxicity induced by carbon nanotubes in Kupffer cells.

The large majority of in vitro nanotoxicological studies have used immortalized cell lines for their practicality. However, results from nanoparticle ...

Neutrophil Isolation and Analysis to Determine their Role in Lymphoma Cell Sensitivity to Therapeutic Agents

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of inflammation. They are key players in the innate immune system and play major roles in cancer biology. Neutrophils have been proposed as key mediators of malignant transformation, tumor progression, angiogenesis and in the modulation of the antitumor immunity; through their release of soluble factors or their interaction with tumor cells. To characterize the specific functions of neutrophils, a fast and reliable method is coveted for in vitro isolation of neutrophils from human blood. Here, a density gradient separation method is demonstrated to isolate neutrophils as well as mononuclear cells from the blood. The procedure consists of layering the density gradient solution such as Ficoll carefully above the diluted blood obtained from patients diagnosed with chronic lymphocytic leukemia (CLL), followed by centrifugation, isolation of mononuclear layer, separation of neutrophils from RBCsby dextran then lysis of residual erythrocytes. This method has been shown to isolate neutrophils &#8805; 90 % pure. To mimic the tumor microenvironment, 3-dimensional (3D) experiments were performed using basement membrane matrix such as Matrigel. Given the short half-life of neutrophils in vitro, 3D experiments with fresh human neutrophils cannot be performed. For this reason promyelocytic HL60 cells are differentiated along the granulocytic pathway using the differentiation inducers dimethyl sulfoxide (DMSO) and retinoic acid (RA). The aim of our experiments is to study the role of neutrophils on the sensitivity of lymphoma cells to anti-lymphoma agents. However these methods can be generalized to study the interactions of neutrophils or neutrophil-like cells with a large range of cell types in different situations.

Neutrophils are the most abundant type of white blood cells. The isolation of neutrophils from human blood by density gradient separation method and the differentiation of human promyelocytic (HL60) cells along the granulocytic pathway are described here; to test their role on sensitivity of lymphoma cells to anti-lymphoma agents.

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of ...

Evaluation of the Efficacy And Toxicity of RNAs Targeting HIV-1 Production for Use in Gene or Drug Therapy

Small RNA therapies targeting post-integration steps in the HIV-1 replication cycle are among the top candidates for gene therapy and have the potential to be used as drug therapies for HIV-1 infection. Post-integration inhibitors include ribozymes, short hairpin (sh) RNAs, small interfering (si) RNAs, U1 interference (U1i) RNAs and RNA aptamers. Many of these have been identified using transient co-transfection assays with an HIV-1 expression plasmid and some have advanced to clinical trials. In addition to measures of efficacy, small RNAs have been evaluated for their potential to affect the expression of human RNAs, alter cell growth and/or differentiation, and elicit innate immune responses. In the protocols described here, a set of transient transfection assays designed to evaluate the efficacy and toxicity of RNA molecules targeting post-integration steps in the HIV-1 replication cycle are described. We have used these assays to identify new ribozymes and optimize the format of shRNAs and siRNAs targeting HIV-1 RNA. The methods provide a quick set of assays that are useful for screening new anti-HIV-1 RNAs and could be adapted to screen other post-integration inhibitors of HIV-1 replication.

Methods to evaluate the efficacy and toxicity of RNA molecules targeting post-integration steps of the HIV-1 replication cycle are described. These methods are useful for screening new molecules and optimizing the format of existing ones.

Small RNA therapies targeting post-integration steps in the HIV-1 replication cycle are among the top candidates for gene therapy and have the potential ...

Extraction of Hemocytes from Drosophila melanogaster Larvae for Microbial Infection and Analysis

During the pathogenic infection of Drosophila melanogaster, hemocytes play an important role in the immune response throughout the infection. Thus, the goal of this protocol is to develop a method to visualize the pathogen invasion in a specific immune compartment of flies, namely hemocytes. Using the method presented here, up to 3 &#215; 106 live hemocytes can be obtained from 200 Drosophila 3rd instar larvae in 30 min for ex vivo infection. Alternatively, hemocytes can be infected in vivo through injection of 3rd instar larvae followed by hemocyte extraction up to 24 h post-infection. These infected primary cells were fixed, stained, and imaged using confocal microscopy. Then, 3D representations were generated from the images to definitively show pathogen invasion. Additionally, high-quality RNA for qRT-PCR can be obtained for the detection of pathogen mRNA following infection, and sufficient protein can be extracted from these cells for Western blot analysis. Taken together, we present a method for definite reconciliation of pathogen invasion and confirmation of infection using bacterial and viral pathogen types and an efficient method for hemocyte extraction to obtain enough live hemocytes from Drosophila larvae for ex vivo and in vivo infection experiments.

Extraction of Hemocytes from Drosophila melanogaster Larvae for Microbial Infection and Analysis

This method demonstrates how to visualize pathogen invasion into insect cells with three-dimensional (3D) models. Hemocytes from Drosophila larvae were infected with viral or bacterial pathogens, either ex vivo or in vivo. Infected hemocytes were then fixed and stained for imaging with a confocal microscope and subsequent 3D cellular reconstruction.

During the pathogenic infection of Drosophila melanogaster, hemocytes play an important role in the immune response throughout the infection. Thus, the ...

Characterization of Thymus-dependent and Thymus-independent Immunoglobulin Isotype Responses in Mice Using Enzyme-linked Immunosorbent Assay

Antibodies, also termed as immunoglobulins (Ig), secreted by differentiated B lymphocytes, plasmablasts/plasma cells, in humoral immunity provide a formidable defense against invading pathogens via diverse mechanisms. One major goal of vaccination is to induce protective antigen-specific antibodies to prevent life-threatening infections. Both thymus-dependent (TD) and thymus-independent (TI) antigens can elicit robust antigen-specific IgM responses and can also induce the production of isotype-switched antibodies (IgG, IgA and IgE) as well as the generation of memory B cells with the help provided by antigen presenting cells (APCs). Here, we describe a protocol to characterize TD and TI Ig isotype responses in mice using enzyme-linked immunosorbent assay (ELISA). In this protocol, TD and TI Ig responses are elicited in mice by intraperitoneal (i.p.) immunization with hapten-conjugated model antigens TNP-KLH (in alum) and TNP-polysaccharide (in PBS), respectively. To induce TD memory response, a booster immunization of TNP-KLH in alum is given at 3 weeks after the first immunization with the same antigen/adjuvant. Mouse sera are harvested at different time points before and after immunization. Total serum Ig levels and TNP-specific antibodies are subsequently quantified using Ig isotype-specific Sandwich and indirect ELISA, respectively. In order to correctly quantify the serum concentration of each Ig isotype, the samples need to be appropriately diluted to fit within the linear range of the standard curves. Using this protocol, we have consistently obtained reliable results with high specificity and sensitivity. When used in combination with other complementary methods such as flow cytometry, in vitro culture of splenic B cells and immunohistochemical staining (IHC), this protocol will allow researchers to gain a comprehensive understanding of antibody responses in a given experimental setting.

In this paper, we describe a protocol to characterize T-dependent and T-independent immunoglobulin (Ig) isotype responses in mice using ELISA. This method used alone or in combination with flow cytometry will allow researchers to identify differences in B cell-mediated Ig isotype responses in mice following T-dependent and T-independent antigen immunization.

Antibodies, also termed as immunoglobulins (Ig), secreted by differentiated B lymphocytes, plasmablasts/plasma cells, in humoral immunity provide a ...

Establishment of Viral Infection and Analysis of Host-Virus Interaction in Drosophila Melanogaster

Virus spreading is a major cause of epidemic diseases. Thus, understanding the interaction between the virus and the host is very important to extend our knowledge of prevention and treatment of viral infection. The fruit fly Drosophila melanogaster has proven to be one of the most efficient and productive model organisms to screen for antiviral factors and investigate virus-host interaction, due to powerful genetic tools and highly conserved innate immune signaling pathways. The procedure described here demonstrates a nano-injection method to establish viral infection and induce systemic antiviral responses in adult flies. The precise control of the viral injection dose in this method enables high experimental reproducibility. Protocols described in this study include the preparation of flies and the virus, the injection method, survival rate analysis, the virus load measurement, and an antiviral pathway assessment. The influence effects of viral infection by the flies' background were mentioned here. This infection method is easy to perform and quantitatively repeatable; it can be applied to screen for host/viral factors involved in virus-host interaction and to dissect the crosstalk between innate immune signaling and other biological pathways in response to viral infection.

Establishment of Viral Infection and Analysis of Host-Virus Interaction in Drosophila Melanogaster

This protocol describes how to establish viral infection in vivo in Drosophila melanogaster using the nano-injection method and basic techniques to analyze virus-host interaction.

Virus spreading is a major cause of epidemic diseases. Thus, understanding the interaction between the virus and the host is very important to extend our ...

Human Colonoid Monolayers to Study Interactions Between Pathogens, Commensals, and Host Intestinal Epithelium

Human 3-dimensional (3D) enteroid or colonoid cultures derived from crypt base stem cells are currently the most advanced ex vivo model of the intestinal epithelium. Due to their closed structures and significant supporting extracellular matrix, 3D cultures are not ideal for host-pathogen studies. Enteroids or colonoids can be grown as epithelial monolayers on permeable tissue culture membranes to allow manipulation of both luminal and basolateral cell surfaces and accompanying fluids. This enhanced luminal surface accessibility facilitates modeling bacterial-host epithelial interactions such as the mucus-degrading ability of enterohemorrhagic E. coli (EHEC) on colonic epithelium. A method for 3D culture fragmentation, monolayer seeding, and transepithelial electrical resistance (TER) measurements to monitor the progress towards confluency and differentiation are described. Colonoid monolayer differentiation yields secreted mucus that can be studied by the immunofluorescence or immunoblotting techniques. More generally, enteroid or colonoid monolayers enable a physiologically-relevant platform to evaluate specific cell populations that may be targeted by pathogenic or commensal microbiota.

Here, we present a protocol to culture human enteroid or colonoid monolayers that have intact barrier function to study host epithelial-microbiota interactions at the cellular and biochemical level.

Human 3-dimensional (3D) enteroid or colonoid cultures derived from crypt base stem cells are currently the most advanced ex vivo model of the intestinal ...