Partial support by grants to MRS is from Natural Sciences and Engineering Research Council of Canada (NSERC), the Harry Botterell Foundation for Neuroscience Research, ARC, and the Garfield Kelly Cardiovascular Research and Development Fund. S.R.A. is a recipient of the Queen's University Research Award and the Robert J. Wilson Fellowship. P.J. is a recipient of the Queen's Graduate Award and the Robert J. Wilson Fellowship. A.G. and S.A. are recipients of the Queen's Graduate Award. S.F. was the recipient of the Ontario Graduate Scholarship in Science and Technology (OGSST). A.G. is the recipient of the Queen's Franklin Bracken Graduate Scholarship. S.A. is the recipient of the Queen's R.S. McLaughlin Graduate Scholarship.

1. Resurrecting Frozen Macrophage Cells
<ol>
<li>	Before resurrecting frozen cells from the -80&deg;C freezer, one needs to prepare culture medium using sterile filtered Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 5 &mu;g/mL of plasmocin. Plasmocin is an antibiotic solution used in our research to eliminate and prevent mycoplasma contamination of cell cultures.</li>
<li>	For one vial of frozen cells, one adds 4 mL, 1 mL of the cultured medium to a 25 cm2 cell culture flask in a sterile biohazard containment hood.</li>
<li>	When the vial of frozen cells are taken from the -80&deg;C freezer, they are quickly thawed by hand warming in the sterile hood, which takes about 2-3 min.</li>
<li>	As soon as the cells are thawed, they are quickly transferred into the flask containing the conditioned medium using a 1mL sterile pipette.</li>
<li>	The flask containing the cells are placed in an tissue culture incubator at 37&deg;C and 5% CO2.</li>
<li>	The cells checked for growth and adherence on a daily basis until they become 75% to 90% confluent using an inverted microscope.</li>
<li>	During the cell culture incubation, 12 mm circular glass slides are sterilized by covering them in 70% ethanol in a large glass petri dish for 1 hr in the biohazard containment cabinet, the alcohol is afterwards removed and stored for reusage, and the wet glass sides are left exposed to the sterile-filtered air flow in the cabinet under a UV for 24 hrs or until they are dry.</li>
</ol>
2. Plating Cells for the Sialidase Assay
<ol>
<li>	Before plating the cells, one single sterile circular glass slide is carefully placed in one well of a BD Falcon 24-well flat-bottom with lid tissue-culture treated polystyrene plate using a sterilized flaming full curved, 4", serrated, stainless steel forcep. For one flask of cells at 75% confluence, we usually use 12 wells of the culture plate.</li>
<li>	For adherent macrophage cells, the DMEM conditioned medium is removed from the flask using a 5 mL sterile pipette in the sterile containment cabinet. Wash the adherent cells once with 1x sterile Tris buffered saline pH 7.4 to remove any serum containing medium, and add 1 mL of calcium-medium free (CMF) phosphate buffered saline at pH 7.4 enough to cover the cells. The cells are placed in the 37&deg;C incubator for approximately 10 min or until the cells start to lift off in the flask. The flask can be gently rocked or shaken to loosen any remaining adherent cells.</li>
<li>	To the 1 mL of suspended cells in the flask, add 3 mL of DMEM conditioned medium. Take 0.5 mL of the suspended cells and sterilely transferred them to the tissue cultured plate containing the 12 mm circular glass slides. Approximately, 0.5 x 106 cells are transferred to the circular glass slides.</li>
<li>	The tissue culture plate containing cells are incubated at 37&deg;C in 5% CO2 for 24 hrs in order to allow for the cells to adhere to the circular glass slides.</li>
</ol>
3. Sialidase Assay
1. Making the Control
<ol>
<li>	Place a microscope slide (frosted: 1 end, 1slide, 25 x 75 x 1 mm) in the containment cabinet or lab bench and add by mixing in sequential order the following compounds: 1 &mu;L DAKO + 1 &mu;L of 4-MUNANA and lastly + 3 &mu;L of Tris buffered saline pH 7.4 (TBS).</li>
<li>	After removing the media from one well containing the cells, gently lift the circular glass slide with the 4" forcep to the corner of the well. Carefully remove the glass slide with the forcep and place the slide with the cells facing onto the mixture solution on the microscope slide.</li>
<li>	Immediately, take the microcope slide to an epi-fluorescent microscopy which has been set for the UV filter and has a digital camera for capturing the fluorescent images.</li>
<li>	Focus the microscope under phase contrast until you can see the cells and then switch to fluorescent mode. Take pictures of the cells under fluorescent at 1 min, 2 min, and 3 min. Take a single picture of the cells under phase contrast.</li>
</ol>
2. Making the Positive Test
<ol>
<li>	Spot the following compounds in the sequential order on another microscope slide: 1 &mu;L DAKO + 1 &mu;L of 4-MUNANA + 2 &mu;L of LPS + 1 &mu;L of TBS.</li>
<li>	Repeat steps 3.1.2 to 3.1.4 above.</li>
</ol>
3. Making the Positive Test together with Neuraminidase inhibitor Tamiflu
<ol>
<li>	Spot the following compounds in the following sequential order on another microscope slide: 1&mu;L DAKO + 1&mu;L of 4-MUNANA + 2 &mu;L of LPS + 1 &mu;L of Tamiflu.</li>
<li>	Tamiflu concentrations are pre-prepared in 1x Tris buffered saline pH 7.4; the final concentration of the compounds in contact with the live cells on the circular glass slide will have a dilution factor of 5.</li>
<li>	Repeat steps 3.1.2 to 3.1.4 above.</li>
</ol>
4. Determination of the Concentration of Inhibitor needed to Inhibit 50% of the Sialidase Activity (IC50)
<ol>
<li> 	To quantify the fluorescent surrounding the cells, the images are analyzed using ImageJ 1.38x with the analyze plugin for measuring RBG. Take 50 random spot readings of the fluorescence surrounding the cells and calculate the mean of the total fluorescence.</li>
<li>	The IC50 is generated from a plot of the inhibitor concentration converted as log units (e.g., log ng/mL) on the x-axis against the mean fluorescence on the y-axis using nonlinear regression.</li>
</ol>
5. Secrets to Success
<ol>
<li>	Make sure the cells in culture are contamination free from mycoplasma. We routinely use Plasmocin in a culture medium to control for this.</li>
<li>	The artificial neuraminidase substrate, 4-MUNANA, should be used freshly prepared. The prepared substrate can be used within a week for the sialidase assay.</li>
<li>	If the cell line has a low receptor expression on the cell surface, one can use a higher dose of the ligand for stimulation.</li>
<li>	We have also experienced that cells passaged for over 6 times might lose their receptor phenotype. Freshly, resurrected cells should be cultured.</li>
</ol> 
6. Representative Results
See animated protocol of the sialidase assay with representative results in the attached <a href="https://www.jove.com/files/ftp_upload/2142/szewczuk_JoVE_sialidase_assay.pptx">Powerpoint file</a>.

<ol>
	<li>Amith, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neu1+desialylation+of+sialyl+alpha-2,3-linked+beta-galactosyl+residues+of+TOLL-like+receptor+4+is+essential+for+receptor+activation+and+cellular+signaling.">Neu1 desialylation of sialyl alpha-2,3-linked beta-galactosyl residues of TOLL-like receptor 4 is essential for receptor activation and cellular signaling.</a> Cell Signal. 22, 314-324 (2010).</li><li>Amith, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dependence+of+pathogen+molecule-induced+Toll-like+receptor+activation+and+cell+function+on+Neu1+sialidase.">Dependence of pathogen molecule-induced Toll-like receptor activation and cell function on Neu1 sialidase.</a> Glycoconjugate Journal. 26, 1197-1212 (2009).</li><li>Woronowicz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dependence+of+neurotrophic+factor+activation+of+Trk+tyrosine+kinase+receptors+on+cellular+sialidase.">Dependence of neurotrophic factor activation of Trk tyrosine kinase receptors on cellular sialidase.</a> Glycobiology. 17, 10-24 (2007).</li><li>Jayanth, P., Amith, S. R., Gee, K., Szewczuk, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neu1+Sialidase+and+Matrix+Metalloproteinase-9+Cross-talk+is+Essential+for+Neurotrophin+Activation+of+Trk+Receptors+and+Cellular+Signaling.">Neu1 Sialidase and Matrix Metalloproteinase-9 Cross-talk is Essential for Neurotrophin Activation of Trk Receptors and Cellular Signaling.</a> Cell. Signal. 22, 1193-1205 (2010).</li><li>Finlay, T. M., Jayanth, P., Amith, S. R., Glimour, A., Guzzo, C., Gee, K., Beyaert, R., Szewczuk, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thymoquinone+from+nutraceutical+black+cumin+oil+activates+Neu4+sialidase+in+live+macrophage,+dendritic,+and+normal+and+type+I+sialidosis+human+fibroblast+cells+via+GPCR+G&#945;i+proteins+and+matrix+metalloproteinase-9.">Thymoquinone from nutraceutical black cumin oil activates Neu4 sialidase in live macrophage, dendritic, and normal and type I sialidosis human fibroblast cells via GPCR G&#945;i proteins and matrix metalloproteinase-9.</a> Glycoconj J. 27, 329-348 (2010).</li><li>Seyrantepe, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+Phagocytosis+in+Macrophages+by+Neuraminidase+1.">Regulation of Phagocytosis in Macrophages by Neuraminidase 1.</a> Journal of Biological Chemistry. 285, 206-215 (2010).</li></ol>

S.R.A. and P.J. contributed equally as first authors.

Using the newly developed assay to detect sialidase activity in live macrophage cells 2, we used this technology to detect sialidase activity in ligand-induced sialidase activity in live BMC-2 macrophage cells in a dose dependent manner as well in live DC-2.4 dendritic cells, HEK-TLR4/MD2, HEK293, SP1 mammary adenocarcinoma cells, human WT and 1140F01 and WG0544 type I sialidosis fibroblast cells. Neuraminidase inhibitors like Tamiflu (oseltamivir phosphate) inhibited thymoquinone-induced sialidase activity i...

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		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
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<tr>
<td>DMEM</td>
<td>&nbsp;</td>
<td>Gibco, Rockville, MD</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>4-MUNANA</td>
<td>&nbsp;</td>
<td>Biosynth International Inc., Itasca, IL, USA</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Fetal calf serum</td>
<td>&nbsp;</td>
<td>HyClone, Logan, Utah, USA</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>DakoCytomation, Fluorescent Mounting Media</td>
<td>&nbsp;</td>
<td>DAKO North America, Inc., Carpintenia, CA</td>
<td>S3023</td>
<td>15 mL</td>
</tr>
<tr>
<td>Tamiflu (Oseltamivir Phosphate)</td>
<td>&nbsp;</td>
<td>Hoffman La Roche</td>
<td>&nbsp;</td>
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detection of  neu1 sialidase activity in regulating toll-like receptor activation

Mammalian Toll-like receptors (TLRs) are a family of receptors that recognize pathogen-associated molecular patterns. Not only are TLRs crucial sensors of microbial (e.g., viruses, bacteria and parasite) infections, they also play an important role in the pathophysiology of infectious diseases, inflammatory diseases, and possibly in autoimmune diseases. Thus, the intensity and duration of TLR responses against infectious diseases must be tightly controlled. It follows that understanding the structural integrity of sensor receptors, their ligand interactions and signaling components is essential for subsequent immunological protection. It would also provide important opportunities for disease modification through sensor manipulation. Although the signaling pathways of TLR sensors are well characterized, the parameters controlling interactions between the sensors and their ligands still remain poorly defined. We have recently identified a novel mechanism of TLR activation by its natural ligand, which has not been previously observed 1,2. It suggests that ligand-induced TLR activation is tightly controlled by Neu1 sialidase activation. We have also reported that Neu1 tightly regulates neurotrophin receptors like TrkA and TrkB 3, which involve Neu1 and matrix metalloproteinase-9 (MMP-9) cross-talk in complex with the receptors 4. The sialidase assay has been initially use to find a novel ligand, thymoquinone, in the activation of Neu4 sialidase on the cell surface of macrophages, dendritic cells and fibroblast cells via GPCR G&alpha;i proteins and MMP-9 5. For TLR receptors, our data indicate that Neu1 sialidase is already in complex with TLR-2, -3 and -4 receptors, and is induced upon ligand binding to either receptor. Activated Neu1 sialidase hydrolyzes sialyl &alpha;-2,3-linked &beta;-galactosyl residues distant from ligand binding to remove steric hinderance to TLR-4 dimerization, MyD88/TLR4 complex recruitment, NFkB activation and pro-inflammatory cell responses. In a collaborative report, Neu1 sialidase has been shown to regulate phagocytosis in macrophage cells 6. Taken together, the sialidase assay has provided us with powerful insights to the molecular mechanisms of ligand-induced receptor activation. Although the precise relationship between Neu1 sialidase and the activation of TLR, Trk receptors has yet to be fully elucidated, it would represent a new or pioneering approach to cell regulation pathways.

Watch this Scientific Journal Video about Detection of  Neu1 Sialidase Activity in Regulating TOLL-like Receptor Activation at JoVE.com

Detection of  Neu1 Sialidase Activity in Regulating TOLL-like Receptor Activation

The sialidase assay is a simple technical approach that will elucidate novel molecular mechanism(s) of TLR sensors of microbial infections and involvement in inflammatory diseases at the receptor level on the cell surface of live macrophages.

Mammalian Toll-like receptors (TLRs) are a family of receptors that recognize pathogen-associated molecular patterns. Not only are TLRs crucial sensors of ...

detection-neu1-sialidase-activity-regulating-toll-like-receptor

Research

JoVE Journal

Immunology and Infection

11.5K Aufrufe.  Queen's University - Kingston, Ontario. Die Sialidase-Test ist eine einfache technische Ansatz, der neuartige molekulare Mechanismus (s) der TLR-Sensoren von mikrobiellen Infektionen und die Beteiligung an entzündlichen Erkrankungen an der Rezeptor-Ebene auf der Zelloberfläche von Live-Makrophagen aufzuklären wird.

Serie: Detection of  Neu1 Sialidase Activity in Regulating TOLL-like Receptor Activation

Combination of Adhesive-tape-based Sampling and Fluorescence in situ Hybridization for Rapid Detection of Salmonella on Fresh Produce

This protocol describes a simple approach for adhesive-tape-based sampling of tomato and other fresh produce surfaces, followed by on-tape fluorescence in situ hybridization (FISH) for rapid culture-independent detection of Salmonella spp. Cell-charged tapes can also be placed face-down on selective agar for solid-phase enrichment prior to detection. Alternatively, low-volume liquid enrichments (liquid surface miniculture) can be performed on the surface of the tape in non-selective broth, followed by FISH and analysis via flow cytometry. To begin, sterile adhesive tape is brought into contact with fresh produce, gentle pressure is applied, and the tape is removed, physically extracting microbes present on these surfaces. Tapes are mounted sticky-side up onto glass microscope slides and the sampled cells are fixed with 10% formalin (30 min) and dehydrated using a graded ethanol series (50, 80, and 95%; 3 min each concentration). Next, cell-charged tapes are spotted with buffer containing a Salmonella-targeted DNA probe cocktail and hybridized for 15 - 30 min at 55&deg;C, followed by a brief rinse in a washing buffer to remove unbound probe. Adherent, FISH-labeled cells are then counterstained with the DNA dye 4',6-diamidino-2-phenylindole (DAPI) and results are viewed using fluorescence microscopy. For solid-phase enrichment, cell-charged tapes are placed face-down on a suitable selective agar surface and incubated to allow in situ growth of Salmonella microcolonies, followed by FISH and microscopy as described above. For liquid surface miniculture, cell-charged tapes are placed sticky side up and a silicone perfusion chamber is applied so that the tape and microscope slide form the bottom of a water-tight chamber into which a small volume (&le; 500 &mu;L) of Trypticase Soy Broth (TSB) is introduced. The inlet ports are sealed and the chambers are incubated at 35 - 37&deg;C, allowing growth-based amplification of tape-extracted microbes. Following incubation, inlet ports are unsealed, cells are detached and mixed with vigorous back and forth pipetting, harvested via centrifugation and fixed in 10% neutral buffered formalin. Finally, samples are hybridized and examined via flow cytometry to reveal the presence of Salmonella spp. As described here, our "tape-FISH" approach can provide simple and rapid sampling and detection of Salmonella on tomato surfaces. We have also used this approach for sampling other types of fresh produce, including spinach and jalape&ntilde;o peppers.

Combination of Adhesive-tape-based Sampling and Fluorescence in situ Hybridization for Rapid Detection of Salmonella on Fresh Produce

This protocol describes a simple adhesive-tape-based approach for sampling of tomato and other fresh produce surfaces, followed by rapid whole cell detection of Salmonella using fluorescence in situ hybridization (FISH).

This protocol describes a simple approach for adhesive-tape-based sampling of tomato and other fresh produce surfaces, followed by on-tape fluorescence in ...

Quantitative Imaging of Lineage-specific Toll-like Receptor-mediated Signaling in Monocytes and Dendritic Cells from Small Samples of Human Blood

Individual variations in immune status determine responses to infection and contribute to disease severity and outcome. Aging is associated with an increased susceptibility to viral and bacterial infections and decreased responsiveness to vaccines with a well-documented decline in humoral as well as cell-mediated immune responses1,2. We have recently assessed the effects of aging on Toll-like receptors (TLRs), key components of the innate immune system that detect microbial infection and trigger antimicrobial host defense responses3. In a large cohort of healthy human donors, we showed that peripheral blood monocytes from the elderly have decreased expression and function of certain TLRs4 and similar reduced TLR levels and signaling responses in dendritic cells (DCs), antigen-presenting cells that are pivotal in the linkage between innate and adaptive immunity5. We have shown dysregulation of TLR3 in macrophages and lower production of IFN by DCs from elderly donors in response to infection with West Nile virus6,7. 
Paramount to our understanding of immunosenescence and to therapeutic intervention is a detailed understanding of specific cell types responding and the mechanism(s) of signal transduction. Traditional studies of immune responses through imaging of primary cells and surveying cell markers by FACS or immunoblot have advanced our understanding significantly, however, these studies are generally limited technically by the small sample volume available from patients and the inability to conduct complex laboratory techniques on multiple human samples. ImageStream combines quantitative flow cytometry with simultaneous high-resolution digital imaging and thus facilitates investigation in multiple cell populations contemporaneously for an efficient capture of patient susceptibility. Here we demonstrate the use of ImageStream in DCs to assess TLR7/8 activation-mediated increases in phosphorylation and nuclear translocation of a key transcription factor, NF-&kappa;B, which initiates transcription of numerous genes that are critical for immune responses8. Using this technology, we have also recently demonstrated a previously unrecognized alteration of TLR5 signaling and the NF-&kappa;B pathway in monocytes from older donors that may contribute to altered immune responsiveness in aging9.

We describe use of ImageStream technology (<a href="http://www.amnis.com/" target="_blank">www.amnis.com</a>), which combines quantitative flow cytometry with simultaneous high-resolution digital imaging, to quantify cellular mechanisms of primary immune cells from well-defined patient cohorts. Our studies provide a blueprint for translational investigations to quantify lineage specific cellular responses in small samples from subject cohorts.

Individual variations in immune status determine responses to infection and contribute to disease severity and outcome.  Aging is associated with an ...

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne relapsing fever (Borrelia spp.), Rocky Mountain Spotted fever (Rickettsia rickettsii), ehrlichiosis (Ehrlichia chaffeensis and E. equi), anaplasmosis (Anaplasma phagocytophilum), encephalitis (tick-borne encephalitis virus), babesiosis (Babesia spp.), Colorado tick fever (Coltivirus), and tularemia (Francisella tularensis) 1-8. To be properly transmitted into the host these infectious agents differentially regulate gene expression, interact with tick proteins, and migrate through the tick 3,9-13. For example, the Lyme disease agent, Borrelia burgdorferi, adapts through differential gene expression to the feast and famine stages of the tick's enzootic cycle 14,15. Furthermore, as an Ixodes tick consumes a bloodmeal Borrelia replicate and migrate from the midgut into the hemocoel, where they travel to the salivary glands and are transmitted into the host with the expelled saliva 9,16-19.
As a tick feeds the host typically responds with a strong hemostatic and innate immune response 11,13,20-22. Despite these host responses, I. scapularis can feed for several days because tick saliva contains proteins that are immunomodulatory, lytic agents, anticoagulants, and fibrinolysins to aid the tick feeding 3,11,20,21,23. The immunomodulatory activities possessed by tick saliva or salivary gland extract (SGE) facilitate transmission, proliferation, and dissemination of numerous tick-borne pathogens 3,20,24-27. To further understand how tick-borne infectious agents cause disease it is essential to dissect actively feeding ticks and collect tick saliva. This video protocol demonstrates dissection techniques for the collection of hemolymph and the removal of salivary glands from actively feeding I. scapularis nymphs after 48 and 72 hours post mouse placement. We also demonstrate saliva collection from an adult female I. scapularis tick.

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

The collection of infected tick hemolymph, salivary glands, and saliva is important to study how tick-borne pathogens cause disease. In this protocol we demonstrate how to collect hemolymph and salivary glands from feeding Ixodes scapularis nymphs. We also demonstrate saliva collection from female I. scapularis adults.

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne ...

Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells

Antibodies against red blood cells (RBCs) can lead to complement activation resulting in an accelerated clearance via complement receptors in the liver (extravascular hemolysis) or leading to intravascular lysis of RBCs. Alloantibodies (e.g. ABO) or autoantibodies to RBC antigens (as seen in autoimmune hemolytic anemia, AIHA) leading to complement activation are potentially harmful and can be - especially when leading to intravascular lysis - fatal1. Currently, complement activation due to (auto)-antibodies on RBCs is assessed in vitro by using the Coombs test reflecting complement deposition on RBC or by a nonquantitative hemolytic assay reflecting RBC lysis1-4. However, to assess the efficacy of complement inhibitors, it is mandatory to have quantitative techniques. Here we describe two such techniques. First, an assay to detect C3 and C4 deposition on red blood cells that is induced by antibodies in patient serum is presented. For this, FACS analysis is used with fluorescently labeled anti-C3 or anti-C4 antibodies. Next, a quantitative hemolytic assay is described. In this assay, complement-mediated hemolysis induced by patient serum is measured making use of spectrophotometric&#160;detection of the released hemoglobin. Both of these assays are very reproducible and quantitative, facilitating studies of antibody-induced complement activation.

Here we describe two assays for measuring complement activation induced by antibodies against red blood cells. The major advantage over the current assays is their quantitative and easy-to-interpret nature.

Antibodies against red blood cells (RBCs) can lead to complement activation resulting in an accelerated clearance via complement receptors in the liver ...

Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1&#946; in Human Monocyte-derived Dendritic Cells

Inflammatory processes resulting from the secretion of Interleukin (IL)-1 family cytokines by immune cells lead to local or systemic inflammation, tissue remodeling and repair, and virologic control1,2 . Interleukin-1&#946; is an essential element of the innate immune response and contributes to eliminate invading pathogens while preventing the establishment of persistent infection1-5.
Inflammasomes are the key signaling platform for the activation of interleukin 1 converting enzyme (ICE or Caspase-1). The NLRP3 inflammasome requires at least two signals in DCs to cause IL-1&#946; secretion6. Pro-IL-1&#946; protein expression is limited in resting cells; therefore a priming signal is required for IL-1&#946; transcription and protein expression. A second signal sensed by NLRP3 results in the formation of the multi-protein NLRP3 inflammasome. The ability of dendritic cells to respond to the signals required for IL-1&#946; secretion can be tested using a synthetic purine, R848, which is sensed by TLR8 in human monocyte derived dendritic cells&#160;(moDCs) to prime cells, followed by activation of the NLRP3 inflammasome with the bacterial toxin and potassium ionophore, nigericin.
Monocyte derived DCs&#160;are easily produced in culture and provide significantly more cells than purified human myeloid DCs. The method presented here differs from other inflammasome assays in that it uses in vitro human, instead of mouse derived, DCs thus allowing for the study of the inflammasome in human disease and infection.

Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1&amp;#946; in Human Monocyte-derived Dendritic Cells

Dendritic cells (DCs)&#160;secrete IL-1&#946; in response to TLR8 recognition of synthetic purine, R848, followed by NLRP3 inflammasome activation with nigericin, therefore, IL-1&#946; can be used to measure NLRP3 inflammasome activity. Intracellular cytokine staining, immunoblotting, and ELISA are used to accurately measure NLRP3 inflammasome priming and activation via IL-1&#946; expression.

Inflammatory processes resulting from the secretion of Interleukin (IL)-1 family cytokines by immune cells lead to local or systemic inflammation, tissue ...

Isolation of Murine Peritoneal Macrophages to Carry Out Gene Expression Analysis Upon Toll-like Receptors Stimulation

During infection and inflammation, circulating monocytes leave the bloodstream and migrate into tissues, where they differentiate into macrophages. Macrophages express surface Toll-like receptors (TLRs), which recognize molecular patterns conserved through evolution in a wide range of microorganisms. TLRs play a central role in macrophage activation which is usually associated with gene expression alteration. Macrophages are critical in many diseases and have emerged as attractive targets for therapy. In the following protocol, we describe a procedure to isolate murine peritoneal macrophages using Brewer&#8217;s thioglycollate medium. The latter will boost monocyte migration into the peritoneum, accordingly this will raise macrophage yield by 10-fold. Several studies have been carried out using bone marrow, spleen or peritoneal derived macrophages. However, peritoneal macrophages were shown to be more mature upon isolation and are more stable in their functionality and phenotype. Thus, macrophages isolated from murine peritoneal cavity present an important cell population that can serve in different immunological and metabolic studies. Once isolated, macrophages were stimulated with different TLR ligands and consequently&#160;gene expression was evaluated.

We describe here a simple protocol to isolate murine peritoneal macrophages. This procedure is followed by RNA extraction to carry out gene expression analysis upon Toll-like receptors stimulation.

During infection and inflammation, circulating monocytes leave the bloodstream and migrate into tissues, where they differentiate into macrophages. ...

Isolation and Activation of Murine Lymphocytes

B and T cells, with their extremely diverse antigen-receptor repertoires, have the ability to mount specific immune responses against almost any invading pathogen1,2. Understandably, such intricate abilities are controlled by a large number of molecules involved in various cellular processes to ensure timely and spatially regulated immune responses3. Here, we describe experimental procedures that allow rapid isolation of highly purified murine lymphocytes using magnetic cell sorting technology. The resulting purified lymphocytes can then be subjected to various in vitro or in vivo functional assays, such as the determination of lymphocyte signaling capacity upon stimulation by immunoblotting4 and the investigation of proliferative abilities by 3H-thymidine incorporation or carboxyfluorescein diacetate succinimidyl ester (CFSE) labeling5-7. In addition to comparing the functional capacities of control and genetically modified lymphocytes, we can also determine the T cell stimulatory capacity of antigen-presenting cells (APCs) in vivo, as shown in our representative results using transplanted CFSE-labeled OT-I T cells.

Lymphocytes are the major players in adaptive immune responses. Here, we present a lymphocyte purification protocol to determine the physiological functions of the desired molecules in lymphocyte activation in vitro and in vivo. The described experimental procedures are suitable for comparing functional capacities between control and genetically modified lymphocytes.

B and T cells, with their extremely diverse antigen-receptor repertoires, have the ability to mount specific immune responses against almost any invading ...

Flow Cytometric Analysis of Natural Killer Cell Lytic Activity in Human Whole Blood

NK cell cytotoxicity is a widely used measure to determine the effect of outside intervention on NK cell function. However, the accuracy and reproducibility of this assay can be considered unstable, either because of user&#39;s errors or because of the sensitivity of NK cells to experimental manipulation. To eliminate these issues, a workflow that reduces them to a minimum was established and is presented here. To illustrate, we obtained blood samples, at various time points, from runners (n = 4) that were submitted to an intense bout of exercise. First, NK cells are simultaneously identified and isolated through CD56 tagging and magnetic-based sorting, directly from whole blood and from as little as one milliliter. The sorted NK cells are removed of any reagent or capping antibodies. They can be counted in order to establish an accurate NK cell count per milliliter of blood. Secondly, the sorted NK cells (effectors cells or E) can be mixed with 3,3&#39;-Diotadecyloxacarbocyanine Perchlorate (DiO) tagged K562 cells (target cells or T) at an assay-optimal 1:5 T:E ratio, and analyzed using an imaging flow-cytometer that allows for the visualization of each event and the elimination of any false positive or false negatives (such as doublets or effector cells). This workflow can be completed in about 4 h, and allows for very stable results even when working with human samples. When available, research teams can test several experimental interventions in human subjects, and compare measurements across several time points without compromising the data&#39;s integrity.

This work describes an advanced workflow for the accurate and fast determination of NK (Natural Killer) cell count and NK cell cytotoxicity in human blood samples.

NK cell cytotoxicity is a widely used measure to determine the effect of outside intervention on NK cell function. However, the accuracy and ...

Detection of Inflammasome Activation and Pyroptotic Cell Death in Murine Bone Marrow-derived Macrophages

Inflammasomes are innate immune signaling platforms that are required for the successful control of many pathogenic organisms, but also promote inflammatory and autoinflammatory diseases. Inflammasomes are activated by cytosolic pattern recognition receptors, including members of the NOD-like receptor (NLR) family. These receptors oligomerize upon the detection of microbial or damage-associated stimuli. Subsequent recruitment of the adaptor protein ASC forms a microscopically visible inflammasome complex, which activates caspase-1 through proximity-induced auto-activation. Following the activation, caspase-1 cleaves pro-IL-1&#946; and pro-IL-18, leading to the activation and secretion of these pro-inflammatory cytokines. Caspase-1 also mediates the inflammatory form of cell death termed pyroptosis, which features the loss of membrane integrity and cell lysis. Caspase-1 cleaves gasdermin D, releasing the N-terminal fragment which forms plasma membrane pores, leading to osmotic lysis.
In vitro, the activation of caspase-1 can be determined by labeling bone marrow-derived macrophages with the caspase-1 activity probe FAM-YVAD-FMK and by labeling the cells with antibodies against the adaptor protein ASC. This technique allows the identification of inflammasome formation and caspase-1 activation in individual cells using fluorescence microscopy. Pyroptotic cell death can be detected by measuring the release of cytosolic lactate dehydrogenase into the medium. This procedure is simple, cost effective and performed in a 96-well plate format, allowing adaptation for screening. In this manuscript, we show that activation of the NLRP3 inflammasome by nigericin leads to the co-localization of the adaptor protein ASC and active caspase-1, leading to pyroptosis.

We describe the detection of NLRP3 inflammasome activation on cellular basis using fluorescence microscopy and staining for active caspase-1 and the adaptor, ASC. A lactate dehydrogenase release assay is presented to detect pyroptotic lysis on a population basis. These techniques can be adapted to study many aspects of inflammasome biology.

Inflammasomes are innate immune signaling platforms that are required for the successful control of many pathogenic organisms, but also promote ...

A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.

Fecal-oral transmission of acute gastroenteritis occurs from time to time, especially when people who handled food and water are infected by Salmonella spp./Shigella spp. The gold standard method for the detection of Salmonella spp./Shigella spp. is direct culture but this is labor-intensive and time-consuming. Here, we describe a high-throughput platform for Salmonella spp./Shigella spp. screening, using real-time polymerase chain reaction (PCR) combined with guided culture. There are two major stages: real-time PCR and the guided culture. For the first stage (real-time PCR), we explain each step of the method: sample collection, pre-enrichment, DNA extraction and real-time PCR. If the real-time PCR result is positive, then the second stage (guided culture) is performed: selective culture, biochemical identification and serological characterization. We also illustrate representative results generated from it. The protocol described here would be a valuable platform for the rapid, specific, sensitive and high-throughput screening of Salmonella spp./Shigella spp.

A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.

Salmonella spp./Shigella spp. are common pathogens attributed to diarrhea. Here, we describe a high-throughput platform for the screening of Salmonella spp./Shigella spp. using real-time PCR combined with guided culture.

Fecal-oral transmission of acute gastroenteritis occurs from time to time, especially when people who handled food and water are infected by Salmonella ...