Name: an in vitro model of the blood-brain barrier using impedance spectroscopy: a focus on t cell-endothelial cell interaction
Uploaded: 2016-12-08T12:30:00
Description: Watch this Scientific Journal Video about An In Vitro Model of the Blood-brain Barrier Using Impedance Spectroscopy: A Focus on T Cell-endothelial Cell Interaction at JoVE.com

We are grateful to Annika Engbers and Frank Kurth for their excellent technical support and Dr. Markus Sch&#228;fer (nanoAnalytics GmbH) for helpful discussions regarding TEER measurements. This work was supported by the Deutsche Forschungsgemeinschaft (DFG), SFB1009 project A03 to HW and LK, CRC TR128, projects A08; Z1 and B01 to LK and HW, and the Interdisciplinary Center for Clinical Research (Medical Faculty of M&#252;nster) grant number Kl2/2015/14 to LK.

For all experiments, mice were bred and maintained under specific pathogen-free conditions in the central animal facility at the University of M&#252;nster, according to German guidelines for animal care. All experiments were performed according to the guidelines of the animal experimental ethics committee and approved by the local authorities of North Rhine-Westphalia, Germany (LANUV, AZ 84-02.05.20.12.217).
1. MBMEC Isolation and Culture
NOTE: Isolate MBMECs as previously described in detail14 wi...

Several steps of the described protocol are essential for a successful experiment. During the initial MBMEC isolation and culture, it is crucial that work is performed under sterile conditions as much as possible, to prevent the contamination of the cell culture with fungal spores or bacteria. In order to obtain a pure culture of ECs, it is recommended to use a medium containing Puromycin for the first three days, which enables survival of ECs, but not other cells types (especially pericytes)41,42. Another cri...

The blood-brain barrier separates the systemic circulation from the central nervous system (CNS)1-3. It provides a physical barrier that inhibits the free movement of cells and the diffusion of water-soluble molecules and protects the brain from pathogens and potentially harmful substances. In addition to its barrier function, the BBB enables the delivery of oxygen and nutrients to the brain parenchyma, which ensures proper functioning of the neuronal tissue. Functional properties of the BBB are highly regulated by its cellular and acellular components, with highly specialized ECs being its main structural element. ECs of the BBB are characterized by the presence of tight junction (TJ) complexes, the lack of fenestrations, extremely low pinocytic activity, and permanently active transport mechanisms. Other components of the BBB the EC basement membrane, pericytes embedding the endothelium, astrocytic end feet and = associated parenchymal basement membrane also contribute to the development, maintenance and function of the BBB2,4-6 and, together with neurons and microglia, form the neurovascular unit (NVU), which enables proper functioning of the CNS7-9.
In a variety of neurological diseases, such as neurodegenerative, inflammatory or infectious diseases, the function of the BBB is compromised2,5,10. Dysregulation of TJ complexes and molecular transport mechanisms leads to increased BBB permeability, leukocyte extravasation, inflammation and neuronal damage. In order to study BBB properties under such pathophysiological conditions, various in vitro BBB models have been established9,11,12. Together they have provided valuable insights into the changes of barrier integrity, permeability as well as transport mechanisms. These models employ endothelial cells of human, mouse, rat, porcine or bovine origin13-18; primary endothelial cells or cell lines are cultured either as a monoculture or together with pericytes and/or astrocytes in order to mimic more closely the BBB in vivo19-25. In recent years, measurement of transendothelial electrical resistance (TEER) has become a widely accepted tool to assess endothelial barrier properties26,27.
TEER reflects the impedance to the ion flux across the cell monolayer and its decrease provides a sensitive measure of compromised endothelial barrier integrity and hence increased permeability. Various TEER measurement systems have been developed, including Epithelial Voltohmmeter (EVOM), Electric Cell-substrate Impedance Sensing (ECIS), and real-time cell analysis15,28-30. TEER reflects the resistance to the ion flux between adjacent ECs (paracellular route) and is directly proportional to the barrier integrity. In impedance spectroscopy27,31, complex total impedance (Z) is measured, which provides additional information about the barrier integrity by measuring Ccl. Ccl relates to the capacitive current through the cell membrane (transcellular route): the cell layer acts like a capacitor in the equivalent electric circuit, separating the charges on both sides of the membrane and is inversely proportional to the barrier integrity. When grown on permeable inserts, ECs adhere, proliferate and spread over the microporous membrane. This resists the background capacitive current of the insert (which itself acts like a capacitor)&#160;and leads to a decrease in the capacitance until it reaches its minimal level. This is followed by the establishment of TJ complexes that seal off the space between adjacent ECs. This restricts the ion flux through the paracellular route, and TEER increases until it reaches its plateau. Under inflammatory conditions, however, the endothelial barrier is compromised: TEER decreases as TJ complexes get disrupted and Ccl increases as the capacitive component of the insert rises again.
Our TEER measurement uses the automated cell monitoring32 system: it follows the principle of impedance spectroscopy and extends its previous applications. Here, we describe an in vitro BBB model that enables the study of the barrier properties, including the interaction of brain endothelium with immune cells; in particular activated T cells. Such pathophysiological conditions are observed in autoimmune diseases of the CNS, such as multiple sclerosis and its animal model experimental autoimmune encephalomyelitis33-37. Here, a crucial step is the transmigration of encephalitogenic, myelin-specific T cells across the BBB. This is followed by their reactivation in the perivascular space and entry into the brain parenchyma, where they recruit other immune cells and mediate inflammation and subsequent demyelination1,35,38. However, molecular mechanisms of the interaction between such T cells and endothelial cells, the main constituents of the BBB, are not well understood. Our protocol aims to fill this gap and give new insights into the consequences on endothelial cells (i.e., barrier integrity and permeability) upon their direct contact and complex interplay with activated T cells.
The protocol described here makes use of primary mouse brain microvascular endothelial cells, grown as a monolayer on permeable inserts with microporous membranes. Endothelial cells are co-cultured with CD4+ T cells, which can be pre-activated either polyclonally or in an antigen-specific fashion. Co-culture of MBMECs with pre-activated, but not na&#239;ve T cells induces a decrease in TEER and an increase in Ccl, which provides a quantitative measure of the MBMEC dysfunction and barrier disruption. The technique is non-invasive: it uses built-in instead of chopstick electrodes, which prevent major disturbance of the EC monolayer; it can be used to monitor barrier function without the use of cell markers. It makes continuous measurements in an automated fashion and enables an independent assessment of the two barrier parameters (TEER and Ccl) simultaneously over time. The method is also sensitive enough to distinguish between different levels of T cell activation and effects of such T cells on ECs.
It can be used in a wide range of functional assays: different cytokines and/or chemokines implicated in inflammatory processes can be added to the co-culture of MBMECs and T cells; blocking antibodies against cell adhesion molecules on either the EC or T-cell side can be used; and inhibitors of T cell activation markers or of their cytolytic properties can be added during the T-cell priming or their co-culture with ECs. The assay is also useful for T-cell transmigration assays, as it can serve as a quality control of the MBMEC monolayer integrity prior to the addition of T cells. All this makes this method a versatile and reliable tool to study the BBB in vitro, with a focus on the effect of activated T cells on EC monolayer integrity. This is of particular importance for understanding the mechanisms of the BBB disruption in the pathogenesis of autoimmune diseases, such as MS and its animal model EAE, where self-reactive, encephalitogenic T cells cross the BBB and cause inflammation and neuronal damage.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>cellZscope</td>
			<td>nanoAnalytics GmbH</td>
			<td>www.nanoanalytics.com</td>
			<td>including: 24-well Cell Module, Controller, PC with cellZscope software v2.2.2&#160;</td>
		</tr>
		<tr>
			<td>Ultracentrifuge</td>
			<td>Thermo Scientific</td>
			<td>www.thermoscientific.com</td>
			<td>SORVALL RC 6+; rotor F21S-8x50y; for MBMEC isolation</td>
		</tr>
		<tr>
			<td>flow cytometer</td>
			<td>Beckman Coulter</td>
			<td>www.beckmancoulter.com</td>
			<td>for analysis of T cell transmigration</td>
		</tr>
		<tr>
			<td>FlowJo7.6.5 software</td>
			<td>Tree Star</td>
			<td>www.flowjo.com</td>
			<td>for analysis of T cell transmigration</td>
		</tr>
		<tr>
			<td>Oak Ridge centrifuge tubes, PC</td>
			<td>Thermo Fisher Scientific</td>
			<td>3118-0050</td>
			<td>50 ml; for MBMEC isolation</td>
		</tr>
		<tr>
			<td>Transwell membrane inserts - pore size 0.4 &#181;m</td>
			<td>Corning</td>
			<td>3470</td>
			<td>for TEER measurement as the main readout</td>
		</tr>
		<tr>
			<td>Transwell membrane inserts - pore size 3 &#181;m</td>
			<td>Corning</td>
			<td>3472</td>
			<td>for TEER measurement as the quality control prior to T-cell transmigration assay</td>
		</tr>
		<tr>
			<td>24-well cell culture plate</td>
			<td>Greiner</td>
			<td>650 180</td>
			<td>flat-bottom; for MBMEC culture</td>
		</tr>
		<tr>
			<td>96-well cell culture plate</td>
			<td>Costar</td>
			<td>3526</td>
			<td>round-bottom; for immune cell culture</td>
		</tr>
		<tr>
			<td>QuadroMACS Separator</td>
			<td>Miltenyi Biotec</td>
			<td>130-090-976</td>
			<td>for T cell and B cell isolation; supports MACS LS columns</td>
		</tr>
		<tr>
			<td>OctoMACS Separator</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-109</td>
			<td>for dendritic cell isolation; supports MACS MS columns</td>
		</tr>
		<tr>
			<td>Neubauer counting chamber</td>
			<td>Marienfeld</td>
			<td>MF-0640010</td>
			<td>for cell counting</td>
		</tr>
		<tr>
			<td>Cell strainer, 70 &#181;m</td>
			<td>Corning</td>
			<td>352350</td>
			<td>for immune cell isolation</td>
		</tr>
		<tr>
			<td>Cell strainer, 40 &#181;m</td>
			<td>Corning</td>
			<td>352340</td>
			<td>for immune cell isolation</td>
		</tr>
		<tr>
			<td>MACS MultiStand</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-303</td>
			<td>for immune cell isolation</td>
		</tr>
		<tr>
			<td>MACS LS separation columns</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-401</td>
			<td>for T cell and B cell isolation</td>
		</tr>
		<tr>
			<td>MACS MS separation columns</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-201</td>
			<td>for dendritic cell isolation</td>
		</tr>
		<tr>
			<td>Mouse CD4 MicroBeads</td>
			<td>Miltenyi Biotec</td>
			<td>130-049-201</td>
			<td>for CD4+ T cell isolation</td>
		</tr>
		<tr>
			<td>Mouse CD19 MicroBeads</td>
			<td>Miltenyi Biotec</td>
			<td>130-052-201</td>
			<td>for B cell isolation</td>
		</tr>
		<tr>
			<td>Mouse CD11c MicroBeads</td>
			<td>Miltenyi Biotec</td>
			<td>130-052-001</td>
			<td>for dendritic cell isolation</td>
		</tr>
		<tr>
			<td>Collagen type IV from human placenta</td>
			<td>Sigma</td>
			<td>C5533</td>
			<td>for MBMEC coating solution</td>
		</tr>
		<tr>
			<td>Fibronectin from bovine plasma</td>
			<td>Sigma</td>
			<td>F1141-5MG</td>
			<td>for MBMEC coating solution</td>
		</tr>
		<tr>
			<td>Collagenase 2 (CSL2)</td>
			<td>Worthington</td>
			<td>LS004176</td>
			<td>for MBMEC isolation</td>
		</tr>
		<tr>
			<td>Collagenase/Dispase (C/D)</td>
			<td>Roche</td>
			<td>11097113001</td>
			<td>for MBMEC isolation</td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>Sigma</td>
			<td>DN25</td>
			<td>for MBMEC isolation</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Sigma</td>
			<td>F7524</td>
			<td>for MBMEC isolation</td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin (BSA)</td>
			<td>Amresco</td>
			<td>0332-100G</td>
			<td>for MBMEC isolation</td>
		</tr>
		<tr>
			<td>Percoll</td>
			<td>Sigma</td>
			<td>P1644-1L</td>
			<td>for MBMEC isolation</td>
		</tr>
		<tr>
			<td>DMEM (+ GlutaMAX)</td>
			<td>Gibco</td>
			<td>31966-021</td>
			<td>for MBMEC isolation and MBMEC culture medium</td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Sigma</td>
			<td>P4333</td>
			<td>for MBMEC isolation and MBMEC culture medium</td>
		</tr>
		<tr>
			<td>Phosphate-Buffered Saline (PBS)</td>
			<td>Sigma</td>
			<td>D8537</td>
			<td>for MBMEC and immune cell isolation</td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Sigma</td>
			<td>H3393</td>
			<td>for MBMEC culture medium</td>
		</tr>
		<tr>
			<td>Human Basic Fibroblast Growth Factor (bFGF)</td>
			<td>PeproTech</td>
			<td>100-18B</td>
			<td>for MBMEC culture medium</td>
		</tr>
		<tr>
			<td>Puromycin</td>
			<td>Sigma</td>
			<td>P8833</td>
			<td>for MBMEC culture medium; only for the first three days</td>
		</tr>
		<tr>
			<td>0.05% Trypsin-EDTA</td>
			<td>Gibco</td>
			<td>25300-054</td>
			<td>for harvesting MBMECs</td>
		</tr>
		<tr>
			<td>Collagenase Type IA</td>
			<td>Sigma</td>
			<td>C9891</td>
			<td>for dendritic cell isolation</td>
		</tr>
		<tr>
			<td>Trypan Blue solution, 0.4%</td>
			<td>Thermo Fisher Scientific</td>
			<td>15250061</td>
			<td>for cell counting</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma</td>
			<td>E5134</td>
			<td>for immune cell isolation</td>
		</tr>
		<tr>
			<td>IMDM + 1% L-Glutamin</td>
			<td>Gibco</td>
			<td>21980-032</td>
			<td>for T cell culture medium</td>
		</tr>
		<tr>
			<td>X-VIVO 15</td>
			<td>Lonza</td>
			<td>BE04-418Q</td>
			<td>protect from light; for B cell culture medium</td>
		</tr>
		<tr>
			<td>&#946;-mercaptoethanol</td>
			<td>Gibco</td>
			<td>31350-010</td>
			<td>for B cell culture medium</td>
		</tr>
		<tr>
			<td>L-Glutamine (100x Glutamax)</td>
			<td>Gibco</td>
			<td>35050-061</td>
			<td>for B cell culture medium</td>
		</tr>
		<tr>
			<td>mouse MOG35&#8212;55 peptide</td>
			<td>Biotrend</td>
			<td>BP0328</td>
			<td>for antigen-specific T cell activation</td>
		</tr>
		<tr>
			<td>purified anti-mouse CD3 Ab</td>
			<td>BioLegend</td>
			<td>100302</td>
			<td>clone 145-2C11; for polyclonal T cell activation</td>
		</tr>
		<tr>
			<td>purified NA/LE anti-mouse CD28 Ab</td>
			<td>BD Pharmingen</td>
			<td>553294</td>
			<td>clone 37.51; for polyclonal T cell activation</td>
		</tr>
		<tr>
			<td>Recombinant Murine IFN-&#947;</td>
			<td>PeproTech</td>
			<td>315-05</td>
			<td>for T-cell transmigration assays</td>
		</tr>
		<tr>
			<td>Recombinant Murine TNF-&#945;</td>
			<td>PeproTech</td>
			<td>315-01A</td>
			<td>for T-cell transmigration assays</td>
		</tr>
		<tr>
			<td>NA/LE purified anti-mouse IFN-&#947; antibody</td>
			<td>BD Biosciences</td>
			<td>554408</td>
			<td>clone XMG1.2; recommended final concentration: 20 &#181;g/ml</td>
		</tr>
		<tr>
			<td>Granzyme B Inhibitor II</td>
			<td>Calbiochem</td>
			<td>368055</td>
			<td>recommended final concentration: 10 &#181;M</td>
		</tr>
		<tr>
			<td>PE anti-mouse CD4 antibody</td>
			<td>Biolegend</td>
			<td>116005</td>
			<td>clone RM4-4; for analysis of T cell transmigration</td>
		</tr>
	</tbody>
</table>

an in vitro model of the blood-brain barrier using impedance spectroscopy: a focus on t cell-endothelial cell interaction

Breakdown of the blood-brain barrier (BBB) is a critical step in the development of autoimmune diseases such as multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). This process is characterized by the transmigration of activated T cells across brain endothelial cells (ECs), the main constituents of the BBB. However, the consequences on brain EC function upon interaction with such T cells are largely unknown. Here we describe an assay that allows for the evaluation of primary mouse brain microvascular EC (MBMEC) function and barrier integrity during the interaction with T cells over time. The assay makes use of impedance cell spectroscopy, a powerful tool for studying EC monolayer integrity and permeability, by measuring changes in transendothelial electrical resistance (TEER) and cell layer capacitance (Ccl). In direct contact with ECs, stimulated but not na&#239;ve T cells are capable of inducing EC monolayer dysfunction, as visualized by a decrease in TEER and an increase in Ccl. The assay records changes in EC monolayer integrity in a continuous and automated fashion. It is sensitive enough to distinguish between different strengths of stimuli and levels of T cell activation and it enables the investigation of the consequences of a targeted modulation of T cell-EC interaction using a wide range of substances such as antibodies, pharmacological reagents and cytokines. The technique can also be used as a quality control for EC integrity in in vitro T-cell transmigration assays. These applications make it a versatile tool for studying BBB properties under physiological and pathophysiological conditions.

Figure 1 provides a general overview of the in vitro BBB model used to study the interaction between T cells and endothelial cells. The experiment consists of three major steps. The first step is the isolation of primary MBMECs from brain cortices, and their culture for five days. When they reach confluence in the cell culture plate, MBMECs are trypsinized and reseeded onto permeable inserts, which are then placed in the TEER instrument. The TEER and Ccl of MBMEC...

Watch this Scientific Journal Video about An In Vitro Model of the Blood-brain Barrier Using Impedance Spectroscopy: A Focus on T Cell-endothelial Cell Interaction at JoVE.com

An In Vitro Model of the Blood-brain Barrier Using Impedance Spectroscopy: A Focus on T Cell-endothelial Cell Interaction

Here, we describe an in vitro murine model of the blood-brain barrier that makes use of impedance cell spectroscopy, with a focus on the consequences on endothelial cell integrity and permeability upon interaction with activated T cells.

An In Vitro Model of the Blood-brain Barrier Using Impedance Spectroscopy: A Focus on T Cell-endothelial Cell Interaction

Breakdown of the blood-brain barrier (BBB) is a critical step in the development of autoimmune diseases such as multiple sclerosis (MS) and its animal ...

The overall goal of this experiment is to study the consequences on endothelial cell integrity and permeability upon interaction with activated T cells. This method helps to answer key questions in the neuroimmunology field, such as how does the direct interaction between T cells and endothelial cells affect blood-brain barrier integrity and permeability. The main advantage of this technique is that it enables automated, real-time assessment of barrier function upon targeted modulation of T cell and endothelial cell interaction.The implications of this technique extend toward therapy of autoimmune CNS disorders, because it provides insight into T cell mediated blood-brain barrier breakdown, a crucial step into pathogenesis of such diseases. This method focuses on marine blood-brain barrier properties during EAE. But it can also be applied to red or human blood-brain barrier models, as well as studies of other autoimmune CNS disorders.Generally, individuals new to this method may struggle because of possible difficulties with optimal timing of combined primary endothelial cell culture and T cell activation. We first developed this method when we set off to investigate effects of different T cell activation levels on the blood-brain barrier properties during EAE, an animal model of multiple sclerosis. Visual demonstration of this method is critical, as setting up T cell and endothelial cell co-cultures is difficult to learn, because initial variations in T between wells may need to subsequent misrepresentations of the results.To begin this procedure, on day five after MBMEC isolation, precoat the permeable inserts with 80 microliters of MBMEC coating solution per insert. Incubate them at 37 degrees Celsius, and 5%carbon dioxide, for three hours. After removing the MBMEC coating solution from inserts, wash MBMECs by adding two milliliters of room temperature PBS to each well, and aspirating it after one minute, and then repeat this procedure once more.Next, add 0.05%Trypsin EDTA at 300 microliters per well and incubate it for five to ten minutes. Subsequently, add two milliliters of MBMEC medium to each well to stop trypsinization. Then, transfer the collected cells to a 15 milliliter centrifugation tube and centrifuge the sample at 700 times g for eight minutes at four degrees Celsius.After eight minutes, discard the supernatant and resuspend the cells in one milliliter of MBMEC medium without puromycin. To count the cells, mix 90 microliters of 0.04%trypan blue. With 10 microliters of cell suspension, pipette 10 microliters of the mixture between the glass cover and the hemocytometer.Next, cede two times 10 to the fourth cells per insert. Add 810 microliters of MBMEC medium to the lower compartment of each well and place the plate with the inserts in the incubator until ready to proceed with TEER measurement. To stimulate CD4 positive T cells, precoat a round-bottomed 96 well plate with purified anti-mouse CD3 antibody at a desired final concentration for three hours at 37 degree Celsius.After isolating the T cells, wash the precoated plate twice with PBS. Next, add purified anti-CD28 antibody to the isolated T cells at a desired final concentration and mix well. Then, cede the T cells and leave them at 37 degrees Celsius for two to three days.To set up TEER measurement, place the 24 well module of the TEER instrument in the laminar flow hood. Remove the lids and place the inserts with MBMECs in the instrument, using forceps. Next, pipette 810 microliters of the fresh medium to the lower compartment of the module wells, added carefully between the insert and the wall of the module well.After that, close the lids and place the instrument in the incubator. Connect the instrument to the computer. Then, turn on the instrument controller and open the software.In the pop-up window, select New Measurement"Check show TER"and show Ccl"boxes. Then, press start. After completing the first measurement, select check all wells"in the Results tab to see all TEER and Ccl values.Then, save the file. Next, choose the time point to co-culture MBMECs with T cells when Ccl is stable and lower than one microfarad per square centimeter and TEER has reached its maximum level. Carefully inspect the absolute TEER and Ccl values and exclude the wells in which MBMECs have not developed confluent enough monolayers by unchecking such wells.Group the rest of the wells by right-clicking on the wells and selecting add well to new average well"Name it in the pop-up window and do the same for all individual wells to be grouped. Then check all average wells to confirm that all of them have the same initial conditions before the co-culture. In the experiment tab, press pause.Disconnect the instrument and take it out of the incubator. Then, remove the lids in the laminar flow hood. Subsequently, remove some of the medium from the insert at the upper well compartment.Add T cells to MBMECs by carefully pipetting 150 microliters of medium. Then, reconnect the instrument and press resume measurement. After 24 hours, press stop in the experiment tab and save the file.Shown here are the spindle-shaped morphology in the immunofluorescent staining of PECAM-1 and Cldn-5 five days after MBMEC isolation. Here are the TEER and Ccl values before and after grouping of individual wells prior to the addition of T cells. The blue curve is not used for the experiment since MBMECs in this well have not developed TEER as high as in other wells.In this experiment, mark 35 to 55 specific CD4 positive T cells were stimulated in an antigen-specific fashion for five days. Naive T cells and proinflammatory cytokines, interferon gamma and TNF-alpha served as a negative and positive control, respectively. Here, T cells were stimulated by the same amount of anti-CD3 and anti-CD28 antibodies and the ones cultured for three days exhibited a greater propensity for barrier disruption compared to the T cells cultured for only two days.The results here show that stimulated T cells but not their supernatants caused a substantial damage to the MBMECs, indicating the direct contact between T cells and MBMECs is critical for barrier disruption. On the other hand, adding granzyme b inhibitor two to T cell culture restored MBMEC integrity to a greater extent, pointing to the cytolytic molecule as an important player in causing MBMEC damage and subsequent decrease in TEER Once mastered, this experiment can be done in 12 days if it's performed properly. While attempting this procedure, it's important to remember to choose the correct time point for setting up the co-culture of T cells and endothelial cells.Following this procedure other essays can be employed, such as immunofluorescence microscopy, flow cytometry, and probability essays. In order to address additional questions, such as How does this interaction affect tight junction molecule expression permeability and the extent of T cell transmigration? After its development, this technique paved a way for researchers in the field of neuroimmunology to explore autoimmune disorders of the CNS in mice.After watching this video, you should have a good idea of how to assess the direct effects between activated T cells and endothelial cells with regard to blood-brain barrier integrity and permeability.

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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 ...

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological deficiencies. GVHD is caused by mature alloreactive T cells present in the bone marrow graft that are infused into the recipient and cause damage to host organs. However, in mice, T cells must be added to the bone marrow inoculum to cause GVHD. Although extensive work has been done to characterize T cell responses post transplant, bioluminescent imaging technology is a non-invasive method to monitor T cell trafficking patterns in vivo. 
Following lethal irradiation, recipient mice are transplanted with bone marrow cells and splenocytes from donor mice. T cell subsets from L2G85.B6 (transgenic mice that constitutively express luciferase) are included in the transplant. By only transplanting certain T cell subsets, one is able to track specific T cell subsets in vivo, and based on their location, develop hypotheses regarding the role of specific T cell subsets in promoting GVHD at various time points. At predetermined intervals post transplant, recipient mice are imaged using a Xenogen IVIS CCD camera. Light intensity can be quantified using Living Image software to generate a pseudo-color image based on photon intensity (red = high intensity, violet = low intensity). 
Between 4-7 days post transplant, recipient mice begin to show clinical signs of GVHD. Cooke et al.1 developed a scoring system to quantitate disease progression based on the recipient mice fur texture, skin integrity, activity, weight loss, and posture. Mice are scored daily, and euthanized when they become moribund. Recipient mice generally become moribund 20-30 days post transplant. 
Murine models are valuable tools for studying the immunology of GVHD. Selectively transplanting particular T cell subsets allows for careful identification of the roles each subset plays. Non-invasively tracking T cell responses in vivo adds another layer of value to murine GVHD models.

Induction of Graft-versus-host Disease and In Vivo T Cell Monitoring Using an MHC-matched Murine Model

Murine bone marrow transplantation is a widely used technique to study immunological mechanisms governing graft-versus-host disease in humans. The ability to monitor T cell trafficking patterns in vivo allows for detailed analysis of the development and perpetuation of T cell responses during graft-versus-host disease.

Graft-versus-host disease (GVHD) is the limiting barrier to the broad use of bone marrow transplant as a curative therapy for a variety of hematological ...

In Vitro Assay to Evaluate the Impact of Immunoregulatory Pathways on HIV-specific CD4 T Cell Effector Function

T cell exhaustion is a major factor in failed pathogen clearance during chronic viral infections. Immunoregulatory pathways, such as PD-1 and IL-10, are upregulated upon this ongoing antigen exposure and contribute to loss of proliferation, reduced cytolytic function, and impaired cytokine production by CD4 and CD8 T cells. In the murine model of LCMV infection, administration of blocking antibodies against these two pathways augmented T cell responses. However, there is currently no in vitro assay to measure the impact of such blockade on cytokine secretion in cells from human samples. Our protocol and experimental approach enable us to accurately and efficiently quantify the restoration of cytokine production by HIV-specific CD4 T cells from HIV infected subjects.
Here, we depict an in vitro experimental design that enables measurements of cytokine secretion by HIV-specific CD4 T cells and their impact on other cell subsets. CD8 T cells were depleted from whole blood and remaining PBMCs were isolated via Ficoll separation method. CD8-depleted PBMCs were then incubated with blocking antibodies against PD-L1 and/or IL-10R&#945; and, after stimulation with an HIV-1 Gag peptide pool, cells were incubated at 37 &#176;C, 5% CO2. After 48 hr, supernatant was collected for cytokine analysis by beads arrays and cell pellets were collected for either phenotypic analysis using flow cytometry or transcriptional analysis using qRT-PCR. For more detailed analysis, different cell populations were obtained by selective subset depletion from PBMCs or by sorting using flow cytometry before being assessed in the same assays. These methods provide a highly sensitive and specific approach to determine the modulation of cytokine production by antigen-specific T-helper cells and to determine functional interactions between different populations of immune cells.

In Vitro Assay to Evaluate the Impact of Immunoregulatory Pathways on HIV-specific CD4 T Cell Effector Function

We developed an in vitro assay to investigate the role of immunoregulatory pathways in the regulation of cytokine secretion by HIV-specific CD4 T cells.

T cell exhaustion is a major factor in failed pathogen clearance during chronic viral infections. Immunoregulatory pathways, such as PD-1 and IL-10, are ...

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a prerequisite for pneumococcal infections such as pneumonia and otitis media. In vitro adherence assays can be used to study the attachment of pneumococci to epithelial cell monolayers and to investigate potential interventions, such as the use of probiotics, to inhibit pneumococcal&#160;colonization.&#160;The protocol described here is used to investigate the effects of the probiotic Streptococcus salivarius on the adherence of pneumococci to the human epithelial cell line CCL-23 (sometimes referred to as HEp-2 cells). The assay involves three main steps: 1) preparation of epithelial and bacterial cells, 2) addition of bacteria to epithelial cell monolayers, and 3) detection of adherent pneumococci by viable counts (serial dilution and plating) or quantitative real-time PCR (qPCR). This technique is relatively straightforward and does not require specialized equipment other than a tissue culture setup. The assay can be used to test other probiotic species and/or potential inhibitors of pneumococcal colonization and can be easily modified to address other scientific questions regarding pneumococcal adherence and invasion.

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

In vitro adherence assays can be used to study the attachment of Streptococcus pneumoniae to epithelial cell monolayers and to investigate potential interventions such as the use of probiotics for inhibiting pneumococcal colonization.

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a ...

An Ex vivo Model of an Oligodendrocyte-directed T-Cell Attack in Acute Brain Slices

Death of oligodendrocytes accompanied by destruction of neurons and axons are typical histopathological findings in cortical and subcortical grey matter lesions in inflammatory demyelinating disorders like multiple sclerosis (MS). In these disorders, mainly CD8+ T-cells of putative specificity for myelin- and oligodendrocyte-related antigens are found, so that neuronal apoptosis in grey matter lesions may be a collateral effect of these cells. Different types of animal models are established to study the underlying mechanisms of the mentioned pathophysiological processes. However, although they mimic some aspects of MS, it is impossible to dissect the exact mechanism and time course of &#8216;&#8216;collateral&#8217;&#8217; neuronal cell death. To address this course, here we show a protocol to study the mechanisms and time response of neuronal damage following an oligodendrocyte-directed CD8+ T cell attack. To target only the myelin sheath and the oligodendrocytes, in vitro activated oligodendrocyte-specific CD8+ T-cells are transferred into acutely isolated brain slices. After a defined incubation period, myelin and neuronal damage can be analysed in different regions of interest. Potential applications and limitations of this model will be discussed.

An Ex vivo Model of an Oligodendrocyte-directed T-Cell Attack in Acute Brain Slices

To address mechanisms of demyelination and neuronal apoptosis in cortical lesions of inflammatory demyelinating disorders, different animal models are used. We here describe an ex vivo approach by using oligodendrocyte-specific CD8+ T-cells on brain slices, resulting in oligodendroglial and neuronal death. Potential applications and limitations of the model are discussed.

Death of oligodendrocytes accompanied by destruction of neurons and axons are typical histopathological findings in cortical and subcortical grey matter ...

Development of an in vitro model system for studying the interaction of Equus caballus IgE with its high-affinity receptor Fc&#949;RI

The interaction of IgE with its high-affinity Fc receptor (Fc&#949;RI) followed by an antigenic challenge is the principal pathway in IgE mediated allergic reactions. As a consequence of the high affinity binding between IgE and Fc&#949;RI, along with the continuous production of IgE by B cells, allergies usually persist throughout life, with currently no permanent cure available. Horses, especially race horses, which are commonly inbred, are a species of mammals that are very prone to the development of hypersensitivity responses, which can seriously affect their performance. Physiological responses to allergic sensitization in horses mirror that observed in humans and dogs. In this paper we describe the development of an in situ assay system for the quantitative assessment of the release of mediators of the allergic response pertaining to the equine system. To this end, the gene encoding equine Fc&#949;RI&#945; was transfected into and expressed onto the surface of parental Rat Basophil Leukemia (RBL-2H3.1) cells. The gene product of the transfected equine &#945;-chain formed a functional receptor complex with the endogenous rat &#946;- and &#947;-chains 1. The resultant assay system facilitated an assessment of the quantity of mediator secreted from equine Fc&#949;RI&#945; transfected RBL-2H3.1 cells following sensitization with equine IgE and antigenic challenge using &#946;-hexosaminidase release as a readout 2, 3. Mediator release peaked at 36.68% &#177; 4.88% at 100 ng ml-1 of antigen. This assay was modified from previous assays used to study human and canine allergic responses 4, 5. We have also shown that this type of assay system has multiple applications for the development of diagnostic tools and the safety assessment of potential therapeutic intervention strategies in allergic disease 6, 2, 3.

Development of an &lt;em&gt;in vitro&lt;/em&gt; model system for studying the interaction of &lt;em&gt;Equus&lt;/em&gt; &lt;em&gt;caballus&lt;/em&gt; IgE with its high-affinity receptor Fc&amp;#949;RI

The current study describes the development and applications of a genetically engineered assay system based on the transfection of rat basophilic leukemia cells with the equine Fc&#949;RI&#945; gene. Transfected cells express a functional receptor where the release of mediators of the allergic response can be activated by IgE and antigen.

The interaction of IgE with its high-affinity Fc receptor (Fc&#949;RI) followed by an antigenic challenge is the principal pathway in IgE mediated ...

Mouse Na&#239;ve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets

Antigen inexperienced (na&#239;ve) CD4+ T cells undergo expansion and differentiation to effector subsets at the time of T cell receptor (TCR) recognition of cognate antigen presented on MHC class II. The cytokine signals present in the environment at the time of TCR activation are a major factor in determining the effector fate of a na&#239;ve CD4+ T cell. Although the cytokine environment during na&#239;ve T cell activation may be complex and involve both redundant and opposing signals in vivo, the addition of various cytokine combinations during naive CD4+ T cell activation in vitro can readily promote the establishment of effector T helper lineages with hallmark cytokine and transcription factor expression. Such differentiation experiments are commonly used as a first step for the evaluation of targets believed to promote or inhibit the development of certain CD4+ T helper subsets. The addition of mediators, such as signaling agonists, antagonists, or other cytokines, during the differentiation process can also be used to study the influence of a particular target on T cell differentiation. Here, we describe a basic protocol for the isolation of na&#239;ve T cells from mouse and the subsequent steps necessary for polarizing na&#239;ve cells to various T helper effector lineages in vitro.

Mouse Na&amp;#239;ve CD4+ T Cell Isolation and In vitro Differentiation into T Cell Subsets

Na&#239;ve CD4+ T cells polarize to various subsets depending on the environment at the time of activation. The differentiation of na&#239;ve CD4+ T cells to various effector subsets can be achieved in vitro through the addition of T cell receptor stimuli and specific cytokine signals.

Antigen inexperienced (na&#239;ve) CD4+ T cells undergo expansion and differentiation to effector subsets at the time of T cell receptor (TCR) recognition ...

Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the development and persistence of many health related infections. One of the most well described and studied biofilms in human disease occurs in chronic pulmonary infection of cystic fibrosis patients. When studying biofilms in the context of the host, many factors can impact biofilm formation and development. In order to identify how host factors may affect biofilm formation and development, we used a static chambered coverglass method to grow biofilms in the presence of host-derived factors in the form of sputum supernatants. Bacteria are seeded into chambers and exposed to sputum filtrates. Following 48 hr of growth, biofilms are stained with a commercial biofilm viability kit prior to confocal microscopy and analysis. Following image acquisition, biofilm properties can be assessed using different software platforms. This method allows us to visualize key properties of biofilm growth in presence of different substances including antibiotics.

This protocol describes the visualization of biofilm development following exposure to host-factors using a slide chamber model. This model allows for direct visualization of biofilm development as well as analysis of biofilm parameters using computer software programs.

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the ...

Analysis of Lymphocyte Extravasation Using an In Vitro Model of the Human Blood-brain Barrier

Lymphocyte extravasation into the central nervous system (CNS) is critical for immune surveillance. Disease-related alterations of lymphocyte extravasation might result in pathophysiological changes in the CNS. Thus, investigation of lymphocyte migration into the CNS is important to understand inflammatory CNS diseases and to develop new therapy approaches. Here we present an in vitro model of the human blood-brain barrier to study lymphocyte extravasation. Human brain microvascular endothelial cells (HBMEC) are confluently grown on a porous polyethylene terephthalate transwell insert to mimic the endothelium of the blood-brain barrier. Barrier function is validated by zonula occludens immunohistochemistry, transendothelial electrical resistance (TEER) measurements as well as analysis of evans blue permeation. This model allows investigation of the diapedesis of rare lymphocyte subsets such as CD56brightCD16dim/- NK cells. Furthermore, the effects of other cells, cytokines and chemokines, disease-related alterations, and distinct treatment regimens on the migratory capacity of lymphocytes can be studied. Finally, the impact of inflammatory stimuli as well as different treatment regimens on the endothelial barrier can be analyzed.

Analysis of Lymphocyte Extravasation Using an In Vitro Model of the Human Blood-brain Barrier

Here, we describe a human blood-brain barrier model enabling to investigate lymphocyte transmigration into the central nervous system in vitro.

Lymphocyte extravasation into the central nervous system (CNS) is critical for immune surveillance. Disease-related alterations of lymphocyte ...

In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model

Current methodologies for antigen-specific killing are limited to in vitro use or utilized in infectious disease models. However, there is not a protocol specifically intended to measure antigen-specific killing without an infection. This protocol is designed and describes methods to overcome these limitations by allowing for the detection of antigen-specific killing of a target cell by CD8+ T cells in vivo. This is accomplished by merging a vaccination model with a traditional CFSE-labeled target killing assay. This combination allows the researcher to assess the antigen-specific CTL potential directly and quickly as the assay is not dependent upon tumor growth or infection. In addition, the readout is based on flow cytometry and so should be readily accessible to most researchers. The major limitation of the study is identifying the timeline in vivo that is appropriate to the hypothesis being tested. Variations in antigen strength and mutations in the T cells that may result in differential cytolytic function need to be carefully assessed to determine the optimal time for cell harvest and assessment. The appropriate concentration of peptide for vaccination has been optimized for hgp10025-33 and OVA257-264, but further validation would be needed for other peptides that may be more appropriate to a given study. Overall, this protocol allows a quick assessment of killing function in vivo and can be adapted to any given antigen.

In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model

The goal of this protocol is to allow for detection of in vivo antigen-specific killing of a target cell in a murine model.

Current methodologies for antigen-specific killing are limited to in vitro use or utilized in infectious disease models. However, there is not a protocol ...