Name: high-throughput flow cytometry cell-based assay to detect antibodies to n-methyl-d-aspartate receptor or dopamine-2 receptor in human serum
Uploaded: 2013-11-23T14:00:00
Description: Watch this Scientific Journal Video about High-throughput Flow Cytometry Cell-based Assay to Detect Antibodies to N-Methyl-D-aspartate Receptor or Dopamine-2 Receptor in Human Serum at JoVE.com

This work was supported by the Australian National Health and Medical Research Council, Star Scientific Foundation (Australia), Tourette syndrome Association (USA), The Trish Multiple sclerosis Research Foundation and Multiple Sclerosis Research Australia, Petre Foundation (Australia), the Rebecca L.&#160;Cooper Medical Research Foundation (Australia). We thank all the patients and family members who provided samples for our study.

1. Subcloning Strategy to Construct pIRES2-EGFP Vector Encoding D2R or NMDAR
<ol>
	<li>Obtain full-length cDNA clone of human D2R or NMDAR subunit 1 (NR1).</li>
	<li>Choose an expression vector, such as pIRES2-EGFP, which is suitable for expression of transmembrane proteins with an enhanced green fluorescent protein (GFP) reporter under control of an internal ribosome entry site (IRES), enabling both antigens and GFP to be coexpressed in cells separately.</li>
	<li>Subclone human cDNA within pIRES2-EGFP vector.
	<ol>
	...

<ol>
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This paper describes a novel application of flow cytometry live cell-based assay to detect antibodies targeting specific cell surface neuronal proteins using a high-throughput sampler. Using this technique, we report that a subgroup of patients affected with autoimmune CNS diseases have serum antibodies to surface NMDAR or to surface D2R.
Essential steps for optimal antibody detection using this high-throughput flow cytometry live cell-based assay include 1) obtaining a high yield of healthy t...

Over recent years, autoimmune forms of central nervous system (CNS) diseases have been identified. It has been shown that these diseases are associated and defined by the presence of autoantibodies. These antibodies bind to neuronal receptors or synaptic proteins involved in neurotransmission1,2. Different antigens have been detected, such as N-methyl-D-aspartate receptor (NMDAR)3-5, &#947;-aminobutyric acid B receptor (GABAB) receptor6, &#945;-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor7, voltage-gated potassium channel (VGKC) associated proteins: leucine-rich glioma-activated 1 protein (LGL-1) and contactin-associated protein 2 (capsr2)8,9, glutamate receptor5,10, and dopamine-2 receptor (D2R)11. In the past, these autoimmune CNS disorders (mainly called encephalitis) were often undiagnosed and untreated. These novel antibody biomarkers, e.g. NMDAR antibody or D2R antibody, have substantially improved diagnosis and awareness, and have opened treatment options for patients. Indeed, early treatment with immunotherapies is associated with improved outcome11,12.
Traditional methods to detect antibodies, such as enzyme-linked immunosorbent assay (ELISA) and western blot have been used for detection of antibodies in sera. However, they do not readily enable recognition of extracellular or surface epitopes and, rather, may reveal immunoreactivity towards an intracellular epitope. Furthermore, antibodies that bind to the extracellular domain of important proteins involved in neurotransmission are likely to be pathogenic2,3,7,13,14. Therefore, the development of accurate and sensitive assays to discover relevant cell surface or extracellular antibody targets in patients is paramount. The gold standard method in the field is based on the use of live cells, in so-called &#8220;cell-based assays&#8221;. This method involves the expression of an antigen at the surface of mammalian cells (most often human embryonic kidney 293 (HEK293) cells) in its native form by transfection of vectors containing the complete cDNA sequence of the antigen of interest. Live nonpermeabilized cells are then incubated with diluted patient serum and followed by fluorochrome-conjugated anti-human immunoglobulin (Ig) secondary antibody. The intensity or level of fluorescence is then detected and is associated to the level of autoantibody binding. This technique is specific, as only one antigen is overexpressed in cells. The most widely used &#8220;read-out&#8221; has been confocal microscopy analysis after immunocytochemistry4,5,8-10. However, flow cytometry cell-based assays have been successfully used to detect antibodies in patients with demyelinating diseases15-17. In particular, Waters&#160;et al.15 compared the detection of antibody using a panel of antibody detection techniques including cell-based assays followed by microscopy or flow cytometry analyses, and has shown flow cytometry cell-based assay to be the most sensitive, accurate, and reliable method. Therefore, flow cytometry cell-based assay is advantageous as it is quantitative, not investigator-dependent, and does not involve any use of radioactive material. It is also convenient as it allows large patient cohorts to be assayed in a short amount of time.
More recently, we have optimized a high-throughput flow cytometry cell-based assay to detect NMDAR antibody and D2R antibody in patients with autoimmune CNS diseases11. Our group recently detected NMDAR antibody in patient sera using flow cytometry cell-based assay. These NMDAR antibody-positive sera were previously analyzed using confocal microscopy and were also found to be positive11. This protocol outlines a flow cytometry cell-based assay for the detection of conformation-sensitive CNS antibody in patient serum utilizing an automated high-throughput sampler.

<table border="0" cellpadding="0" cellspacing="0" width="751">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">pIRES2-EGFP vector</td>
			<td style="width:187px;">Clontech</td>
			<td style="width:136px;">6029-1</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Human HA-Dopamine-2 receptor (D2R) cDNA</td>
			<td style="width:187px;">Missouri S&#38;T cDNA Resource Centre</td>
			<td style="width:136px;">DRD020TN00</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Human subunit 1 of NMDAR (NR1) cDNA</td>
			<td style="width:187px;"></td>
			<td style="width:136px;"></td>
			<td style="width:173px;">Gift from Prof A. Vincent&#160; (Oxford, UK)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Monoclonal purified mouse anti-human NR1 antibody (clone: 54.1)</td>
			<td style="width:187px;">BD Pharmingen</td>
			<td style="width:136px;">556308</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Mouse purified monoclonal anti-DRD2 IgG (clone: 1B11)</td>
			<td style="width:187px;">Sigma-Aldrich</td>
			<td style="width:136px;">WH0001813M1-50UG</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Alexa Fluor 647 donkey anti-mouse IgG (H + L)</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">A31571</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Alexa Fluor 647 goat anti-human IgG (H + L)</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">A21445</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:255px;">Dulbecco&#8217;s Modified Eagle Medium (1x) 4.5 g/L D-glucose, L-Glutamine and 110 mg/L sodium pyruvate</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">11995-065</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Foetal bovine serum</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">10099-141</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Gentamicin</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">15710-072</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">GlutaMAX</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">35050-061</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Penicillin-streptomycin</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">15140-122</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Geneticin</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">10131-035</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="45">
			<td height="45" style="height:45px;width:255px;">Dulbecco&#39;s Phosphate-Buffered Saline (1x) (-Ca2+/-Mg2+)</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">14190-144</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">TrypLE Express (1x) with Phenol Red</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">12605-028</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">0.9% Sodium chloride</td>
			<td style="width:187px;">Baxter</td>
			<td style="width:136px;">AHF7975</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Polyethylenimine</td>
			<td style="width:187px;">Polysciences Inc</td>
			<td style="width:136px;">9002-98-6</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Versene</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">15040-066</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">XhoI</td>
			<td style="width:187px;">Roche</td>
			<td style="width:136px;">10899194001</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">NheI</td>
			<td style="width:187px;">Roche</td>
			<td style="width:136px;">10885843001</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">PureLink PCR Purification Kit</td>
			<td style="width:187px;">Invitrogen</td>
			<td style="width:136px;">K3100-01</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">JetQuick Gel Extraction Spin Kit</td>
			<td style="width:187px;">Genomed</td>
			<td style="width:136px;">420050</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">T4 DNA Ligase</td>
			<td style="width:187px;">Roche</td>
			<td style="width:136px;">10481220001</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:255px;">Plasmid&#160;Plus&#160;Maxi Kit</td>
			<td style="width:187px;">Qiagen</td>
			<td style="width:136px;">12963</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;"></td>
			<td style="width:187px;"></td>
			<td style="width:136px;"></td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:255px;">Name of Equipment/Software</td>
			<td style="width:187px;">Company</td>
			<td style="width:136px;">Catalog Number</td>
			<td style="width:173px;">Model/Version</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Flow cytometer with high-throughput sampler system</td>
			<td style="width:187px;">BD Biosciences</td>
			<td style="width:136px;"></td>
			<td style="width:173px;">BDLSRII with HTS</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:255px;">Inverted microscope</td>
			<td style="width:187px;">Olympus</td>
			<td style="width:136px;"></td>
			<td style="width:173px;">CKX41 (with mercury lamp and U-RFLT50 power supply)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:255px;">Electronic multichannel pipette (15-300 &#956;l)</td>
			<td style="width:187px;">Eppendorf</td>
			<td style="width:136px;">613-2240P</td>
			<td style="width:173px;">12-channel Xplorer Plus</td>
		</tr>
		<tr height="56">
			<td height="56" style="height:56px;width:255px;">Excel</td>
			<td style="width:187px;">Microsoft</td>
			<td style="width:136px;"></td>
			<td style="width:173px;">2010</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Prism</td>
			<td style="width:187px;">GraphPad Software, Inc.</td>
			<td style="width:136px;"></td>
			<td style="width:173px;">v4</td>
		</tr>
		<tr height="27">
			<td height="27" style="height:27px;width:255px;">FlowJo</td>
			<td style="width:187px;">Treestar</td>
			<td style="width:136px;"></td>
			<td style="width:173px;">v7.5</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">50 ml polypropylene conical tubes</td>
			<td style="width:187px;">BD Biosciences</td>
			<td style="width:136px;">352070</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">6-well plate</td>
			<td style="width:187px;">BD Biosciences</td>
			<td style="width:136px;">353046</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Tissue culture flask (T75)</td>
			<td style="width:187px;">BD Biosciences</td>
			<td style="width:136px;">353136</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:255px;">Parafilm</td>
			<td style="width:187px;">Pechiney Plastic Packaging</td>
			<td style="width:136px;">PM-992</td>
			<td style="width:173px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:255px;">V-bottom 96-well plate</td>
			<td style="width:187px;">Corning</td>
			<td style="width:136px;">651180</td>
			<td style="width:173px;"></td>
		</tr>
	</tbody>
</table>

high-throughput flow cytometry cell-based assay to detect antibodies to n-methyl-d-aspartate receptor or dopamine-2 receptor in human serum

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases in children and adults. These antibodies have been used to guide diagnosis and treatment. Cell-based assays have improved the detection of antibodies in patient serum. They are based on the surface expression of brain antigens on eukaryotic cells, which are then incubated with diluted patient sera followed by fluorochrome-conjugated secondary antibodies. After washing, secondary antibody binding is then analyzed by flow cytometry. Our group has developed a high-throughput flow cytometry live cell-based assay to reliably detect antibodies against specific neurotransmitter receptors. This flow cytometry method is straight forward, quantitative, efficient, and the use of a high-throughput sampler system allows for large patient cohorts to be easily assayed in a short space of time. Additionally, this cell-based assay can be easily adapted to detect antibodies to many different antigenic targets, both from the central nervous system and periphery. Discovering additional novel antibody biomarkers will enable prompt and accurate diagnosis and improve treatment of immune-mediated disorders.

Live HEK293D2R+ and HEK293CTL cells were acquired at the flow cytometer using a high-throughput sampler. During analysis, cells were gated based on forward scatter (size) and side scatter (granularity) parameters (Figures 1A and&#160;1D). Transfected HEK293 cells expressed the reporter molecule, GFP, in the cytoplasm, and untransfected cells were excluded from analysis (Figures 1B and&#160;1E). Within the GFP+ gate, the M...

Watch this Scientific Journal Video about High-throughput Flow Cytometry Cell-based Assay to Detect Antibodies to N-Methyl-D-aspartate Receptor or Dopamine-2 Receptor in Human Serum at JoVE.com

High-throughput Flow Cytometry Cell-based Assay to Detect Antibodies to N-Methyl-D-aspartate Receptor or Dopamine-2 Receptor in Human Serum

Over the recent years, live cell-based assays have been used successfully to detect antibodies against surface and conformational antigens. Here, we describe a method using high-throughput flow cytometry enabling the analysis of large cohorts of patients. Detection of novel antibodies will improve diagnosis and treatment of immune-mediated disorders.

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases ...

high-throughput-flow-cytometry-cell-based-assay-to-detect-antibodies

Research

JoVE Journal

Medicine

The Measurement and Treatment of Suppression in Amblyopia

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current estimates put the prevalence of amblyopia at approximately 1-3%1-3, the majority of cases being monocular2. Amblyopia is most frequently caused by ocular misalignment (strabismus), blur induced by unequal refractive error (anisometropia), and in some cases by form deprivation.
Although amblyopia is initially caused by abnormal visual input in infancy, once established, the visual deficit often remains when normal visual input has been restored using surgery and/or refractive correction. This is because amblyopia is the result of abnormal visual cortex development rather than a problem with the amblyopic eye itself4,5 . Amblyopia is characterized by both monocular and binocular deficits6,7 which include impaired visual acuity and poor or absent stereopsis respectively. The visual dysfunction in amblyopia is often associated with a strong suppression of the inputs from the amblyopic eye under binocular viewing conditions8. Recent work has indicated that suppression may play a central role in both the monocular and binocular deficits associated with amblyopia9,10 .
Current clinical tests for suppression tend to verify the presence or absence of suppression rather than giving a quantitative measurement of the degree of suppression. Here we describe a technique for measuring amblyopic suppression with a compact, portable device11,12 . The device consists of a laptop computer connected to a pair of virtual reality goggles. The novelty of the technique lies in the way we present visual stimuli to measure suppression. Stimuli are shown to the amblyopic eye at high contrast while the contrast of the stimuli shown to the non-amblyopic eye are varied. Patients perform a simple signal/noise task that allows for a precise measurement of the strength of excitatory binocular interactions. The contrast offset at which neither eye has a performance advantage is a measure of the "balance point" and is a direct measure of suppression. This technique has been validated psychophysically both in control13,14 and patient6,9,11 populations.
In addition to measuring suppression this technique also forms the basis of a novel form of treatment to decrease suppression over time and improve binocular and often monocular function in adult patients with amblyopia12,15,16 . This new treatment approach can be deployed either on the goggle system described above or on a specially modified iPod touch device15.

Amblyopia is a developmental disorder of the visual cortex that is often accompanied by strong suppression of one eye. We present a new technique for measuring and treating interocular suppression in patients with amblyopia that can be deployed using virtual reality goggles or a portable iPod Touch device.

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current ...

Stereological and Flow Cytometry Characterization of Leukocyte Subpopulations in Models of Transient or Permanent Cerebral Ischemia

Microglia activation, as well as extravasation of haematogenous macrophages and neutrophils, is believed to play a pivotal role in brain injury after stroke. These myeloid cell subpopulations can display different phenotypes and functions and need to be distinguished and characterized to study their regulation and contribution to tissue damage. This protocol provides two different methodologies for brain immune cell characterization: a precise stereological approach and a flow cytometric analysis. The stereological approach is based on the optical fractionator method, which calculates the total number of cells in an area of interest (infarcted brain) estimated by a systematic random sampling. The second characterization approach provides a simple way to isolate brain leukocyte suspensions and to characterize them by flow cytometry, allowing for the characterization of microglia, infiltrated monocytes and neutrophils of the ischemic tissue. In addition, it also details a cerebral ischemia model in mice that exclusively affects brain cortex, generating highly reproducible infarcts with a low rate of mortality, and the procedure for histological brain processing to characterize infarct volume by the Cavalieri method.

Brain myeloid cells characterization following stroke can be performed by stereology using the optical fractionator method, or by a flow cytometric analysis of brain leukocytes suspensions. Both are useful techniques to perform an accurate phenotypical distinction of the main myeloid cell subsets found in the ischemic brain.

Microglia activation, as well as extravasation of haematogenous macrophages and neutrophils, is believed to play a pivotal role in brain injury after ...

Adapting Human Videofluoroscopic Swallow Study Methods to Detect and Characterize Dysphagia in Murine Disease Models

This study adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating translational dysphagia research. Successful outcomes are dependent upon three critical components: test chambers that permit self-feeding while standing unrestrained in a confined space, recipes that mask the aversive taste/odor of commercially-available oral contrast agents, and a step-by-step test protocol that permits quantification of swallow physiology. Elimination of one or more of these components will have a detrimental impact on the study results. Moreover, the energy level capability of the fluoroscopy system will determine which swallow parameters can be investigated. Most research centers have high energy fluoroscopes designed for use with people and larger animals, which results in exceptionally poor image quality when testing mice and other small rodents. Despite this limitation, we have identified seven VFSS parameters that are consistently quantifiable in mice when using a high energy fluoroscope in combination with the new murine VFSS protocol. We recently obtained a low energy fluoroscopy system with exceptionally high imaging resolution and magnification capabilities that was designed for use with mice and other small rodents. Preliminary work using this new system, in combination with the new murine VFSS protocol, has identified 13 swallow parameters that are consistently quantifiable in mice, which is nearly double the number obtained using conventional (i.e., high energy) fluoroscopes. Identification of additional swallow parameters is expected as we optimize the capabilities of this new system. Results thus far demonstrate the utility of using a low energy fluoroscopy system to detect and quantify subtle changes in swallow physiology that may otherwise be overlooked when using high energy fluoroscopes to investigate murine disease models.

This study successfully adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating translational dysphagia research.

This study adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating ...

Systems Biology of Metabolic Regulation by Estrogen Receptor Signaling in Breast Cancer

With the advent of the -omics approaches our understanding of the chronic diseases like cancer and metabolic syndrome has improved. However, effective mining of the information in the large-scale datasets that are obtained from gene expression microarrays, deep sequencing experiments or metabolic profiling is essential to uncover and then effectively target the critical regulators of diseased cell phenotypes. Estrogen Receptor &#945; (ER&#945;) is one of the master transcription factors regulating the gene programs that are important for estrogen responsive breast cancers. In order to understand to role of ER&#945; signaling in breast cancer metabolism we utilized transcriptomic, cistromic and metabolomic data from MCF-7 cells treated with estradiol. In this report we described generation of samples for RNA-Seq, ChIP-Seq and metabolomics experiments and the integrative computational analysis of the obtained data. This approach is useful in delineating novel molecular mechanisms and gene regulatory circuits that are regulated by a particular transcription factor which impacts metabolism of normal or diseased cells.

Integration of data from genome-wide sequencing experiments and metabolomics experiments is a challenge. In this paper we report, for the first time, generation, analysis and integration of transcriptome, cistrome and metabolome data from breast cancer cells treated with estradiol.

With the advent of the -omics approaches our understanding of the chronic diseases like cancer and metabolic syndrome has improved. However, effective ...

A High Throughput, Multiplexed and Targeted Proteomic CSF Assay to Quantify Neurodegenerative Biomarkers and Apolipoprotein E Isoforms Status

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be important in the development of future novel therapies. Often&#160;potential new biomarkers do not make it&#160;into the clinic&#160;due to limitations&#160;in their development and&#160;high costs.&#160;However,&#160;targeted proteomics using Multiple Reaction Monitoring Liquid Chromatography-tandem/Mass Spectrometry (MRM LC-MS/MS), specifically using triple quadrupole mass spectrometers, is one method that can be used to rapidly evaluate and validate biomarkers&#160;for clinical translation into diagnostic laboratories. Traditionally, this platform has been used extensively for measurement of small molecules&#160;in clinical laboratories, but it is the potential to analyze proteins, that makes it an attractive alternative to ELISA (Enzyme-Linked Immunosorbent Assay)-based methods. We describe here how targeted proteomics can be used to measure multiplexed markers of dementia, including the detection and quantitation of the known risk factor apolipoprotein E isoform 4 (ApoE4).
In order to make the assay suitable for translation, it is designed to be rapid, simple, highly specific and cost effective. To achieve this, every step in the development of the assay must be optimized for the individual proteins and tissues they are analyzed in. This method describes a typical workflow including various tips and tricks to developing a targeted proteomics MRM LC-MS/MS for translation.
The method development is optimized using custom synthesized versions of tryptic quantotypic peptides, which calibrate&#160;the MS for detection and then spiked into CSF to determine correct identification of the endogenous peptide in the chromatographic separation prior to analysis in the MS. To achieve absolute quantitation, stable isotope-labeled internal standard versions of the peptides with short amino acid sequence tags and containing a trypsin cleavage site, are included in the assay.

We describe a high-throughput, multiplex, and targeted proteomic cerebrospinal fluid (CSF) assay developed with potential for clinical translation. The test can quantitate potential markers and risk factors for neurodegeneration, such as the apolipoprotein E variants (E2, E3 and E4), and measure their allelic expression.

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be ...

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators

G protein-coupled receptors (GPCRs) are of great importance to the pharmaceutical industry as they are involved in many human diseases and include well-validated targets for therapeutic intervention. Discovery of lead compounds, including small synthetic molecules, that specifically inhibit the receptor&#39;s function, is an important initial step in drug development and relies on sensitive, specific, and robust cell-based assays. Here, we describe a kinetic cellular assay with a fluorescent readout primarily designed to identify receptor-specific antagonists that inhibit the intracellular Ca2+ release evoked upon the activation of the CXC chemokine receptor 4 (CXCR4) by its endogenous ligand, the CXC chemokine ligand 12 (CXCL12). A key advantage of this method is that it also enables screening of compounds endowed with intrinsic agonistic properties (i.e., compounds eliciting an increase in intracellular Ca2+ concentration in the absence of CXCL12) or compounds modulating the receptor&#39;s function via interaction with allosteric binding sites (i.e., positive and negative allosteric modulators (PAMs and NAMs, respectively)). On the down side, autofluorescent compounds might interfere with the assay&#39;s readout, thereby hampering reliable data interpretation. Most likely this assay can be implemented, with minimal adaptations, as a generic drug discovery assay for many other GPCRs of which the activation leads to a release of intracellular Ca2+.

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators

The described cellular assay is designed for the identification of CXC chemokine receptor 4 (CXCR4)-interacting agents that inhibit or stimulate, either competitively or allosterically, the intracellular Ca2+ release initiated by CXCR4 activation.

G protein-coupled receptors (GPCRs) are of great importance to the pharmaceutical industry as they are involved in many human diseases and include ...

Characterization of Immune Cells in Human Adipose Tissue by Using Flow Cytometry

Infiltration of immune cells in the subcutaneous and visceral adipose tissue (AT) deposits leads to a low-grade inflammation contributing to the development of obesity-associated complications such as type 2 diabetes. To quantitatively and qualitatively investigate the immune cell subsets in human AT deposits, we have developed a flow cytometry approach. The stromal vascular fraction (SVF), containing the immune cells, is isolated from subcutaneous and visceral AT biopsies by collagenase digestion. Adipocytes are removed after centrifugation. The SVF cells are stained for multiple membrane-bound markers selected to differentiate between immune cell subsets and analyzed using flow cytometry. As a result of this approach, pro- and anti-inflammatory macrophage subsets, dendritic cells (DCs), B-cells, CD4+ and CD8+ T-cells, and NK cells can be detected and quantified. This method gives detailed information about immune cells in AT and the amount of each specific subset. Since there are numerous fluorescent antibodies available, our flow cytometry approach can be adjusted to measure various other cellular and intracellular markers of interest.

This article describes a method to analyze immune cell content of adipose tissue by isolation of immune cells from adipose tissue and subsequent analysis using flow cytometry.

Infiltration of immune cells in the subcutaneous and visceral adipose tissue (AT) deposits leads to a low-grade inflammation contributing to the ...

A Flow Cytometry-based Assay for Measuring Mitochondrial Membrane Potential in Cardiac Myocytes After Hypoxia/Reoxygenation

Timely and efficient reperfusion of the occluded coronary artery is the best strategy for decreasing myocardial infarct size in patients with a ST-segment elevated myocardial infarction. However, reperfusion per se can result in further cardiomyocyte death, a phenomenon known as reperfusion injury. The opening of the mitochondrial permeability transition pore (mPTP), with the decrease of the mitochondrial membrane potential (MMP), or mitochondrial depolarization, is universally recognized as the final step of reperfusion injury and is responsible for mitochondrial and cardiomyocyte death. JC-1 is a lipophilic cationic dye that accumulates in mitochondria depending on the value of MMP. The higher the MMP is, the more JC-1 accumulates in the mitochondria. The increasing amounts of JC-1 in mitochondria can be reflected by a fluorescence emission shift from green (~530 nm) to red (~590 nm). Therefore, the reduction of the red/green fluorescence intensity ratio can indicate the depolarization of mitochondria. Here, we take advantage of JC-1 to measure MMP, or the opening of mPTP in human cardiac myocytes after hypoxia/reoxygenation, detected by flow cytometry.

Here, we present a protocol that uses JC-1 dye to assess the mitochondrial membrane potential of cells after being exposed to hypoxia/reoxygenation with or without a protective agent.

Timely and efficient reperfusion of the occluded coronary artery is the best strategy for decreasing myocardial infarct size in patients with a ST-segment ...

High-throughput Nitrobenzoxadiazole-labeled Cholesterol Efflux Assay

Atherosclerosis leads to cardiovascular disease (CVD). It is still unclear whether cholesterol-HDL (cHDL) concentration plays a causal role in atherosclerosis development. However, an important factor in early stages of atheroma plaque formation is cholesterol efflux capacity to HDL (the ability of HDL particles to accept cholesterol from macrophages) in order to avoid foam cell formation. This is a key step in avoiding the accumulation of cholesterol in the endothelium and a part of reverse cholesterol transport (RCT) to eliminate cholesterol through the liver. Cholesterol efflux capacity to serum or plasma in macrophage cell models is a promising tool that can be used as biomarker for atherosclerosis. Traditionally, [3H]-cholesterol has been used in cholesterol efflux assays. In this study, we aim to develop a safer and faster strategy using fluorescent labelled-cholesterol (NBD-cholesterol) in a cellular assay to trace the cholesterol uptake and efflux process in THP-1-derived macrophages. Finally, we optimize and standardize the NBD-cholesterol efflux method and develop a high-throughput analysis using 96-well plates.

Measurement of in vitro cholesterol efflux capacity to serum or plasma in macrophage cell models is a promising tool as a biomarker for atherosclerosis. In the present study, we optimize and standardize a fluorescent NBD-cholesterol efflux method and develop a high-throughput analysis using 96-well plates.

Atherosclerosis leads to cardiovascular disease (CVD). It is still unclear whether cholesterol-HDL (cHDL) concentration plays a causal role in ...

Application of Biochip Microfluidic Technology to Detect Serum Allergen-specific Immunoglobulin E (sIgE)

Allergic disease is common in both adults and children. Identification of the causative allergens is significant in disease management and prevention. However, a specific immunoglobulin E (IgE) measurement system with a high price-performance ratio is lacking in mainland China, especially in the primary care hospitals. This paper describes the principle and operation procedures of using a microfluidic cartridge-based chemiluminescence system to detect allergen-specific IgE in serum. The results were compared with those from ImmunoCAP (System 1), the industrial standard, and the reproducibility of the system to detect patients sensitized to common allergens is evaluated. The results showed that in comparison with ImmunoCAP (System 1), the BioIC System (System 2) has good precision and sensitivity in detecting serum-specific IgE against various inhalant and food allergens but with a significantly lower cost. It can serve as a good alternative to System 1 in primary care hospitals in mainland China who have lower financial affordability.

Application of Biochip Microfluidic Technology to Detect Serum Allergen-specific Immunoglobulin E sIgE

This paper presents a protocol for detecting serum-specific immunoglobulin E with a microfluidic cartridge-based chemiluminescence system and the evaluation of its usefulness in allergy diagnoses.

Allergic disease is common in both adults and children. Identification of the causative allergens is significant in disease management and prevention. ...