Human γδ T cells can recognize and respond to a wide variety of stress-induced antigens, thereby developing innate broad anti-tumor and anti-infective activity.1 The majority of γδ T cells in peripheral blood have the Vγ9Vδ2 T cell receptor. These cells recognize antigen in a major histocompatibility complex-independent manner and develop strong cytolytic and Th1-like effector functions.1Therefore, γδ T cells are attractive candidate effector cells for cancer immunotherapy. Vγ9Vδ2 T cells respond to phosphoantigens such as (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), which is synthesized in bacteria via isoprenoid biosynthesis;2 and isopentenyl pyrophosphate (IPP), which is produced in eukaryotic cells through the mevalonate pathway.3 In physiological condition, the generation of IPP in nontransformed cell is not sufficient for the activation of γδ T cells. Dysregulation of mevalonate pathway in tumor cells leads to accumulation of IPP and γδ T cells activation.3 Because aminobisphosphonates (such as pamidronate or zoledronate) inhibit farnesyl pyrophosphate synthase (FPPS), the enzyme acting downstream of IPP in the mevalonate pathway, intracellular levels of IPP and sensitibity to γδ T cells recognition can be therapeutically increased by aminobisphosphonates. IPP accumulation is less efficient in nontransfomred cells than tumor cells with a pharmacologically relevant concentration of aminobisphosphonates, that allow us immunotherapy for cancer by activating γδ T cells with aminobisphosphonates. 4 Interestingly, IPP accumulates in monocytes when PBMC are treated with aminobisphosphonates, because of efficient drug uptake by these cells. 5 Monocytes that accumulate IPP become antigen-presenting cells and stimulate Vγ9Vδ2 T cells in the peripheral blood.6 Based on these mechanisms, we developed a technique for large-scale expansion of γδ T cell cultures using zoledronate and interleukin-2 (IL-2).7 Other methods for expansion of γδ T cells utilize the synthetic phosphoantigens bromohydrin pyrophosphate (BrHPP)8 or 2-methyl-3-butenyl-1-pyrophosphate (2M3B1PP).9 All of these methods allow ex vivo expansion, resulting in large numbers of γδ T cells for use in adoptive immunotherapy. However, only zoledronate is an FDA-approved commercially available reagent. Zoledronate-expanded γδ T cells display CD27-CD45RA- effector memory phenotype and thier function can be evaluated by IFN-γ production assay. 7
24 Related JoVE Articles!
Ex vivo Expansion of Tumor-reactive T Cells by Means of Bryostatin 1/Ionomycin and the Common Gamma Chain Cytokines Formulation
Institutions: Virginia Commonwealth University- Massey Cancer Center, Virginia Commonwealth University- Massey Cancer Center, Virginia Commonwealth University- Massey Cancer Center.
It was reported that breast cancer patients have pre-existing immune responses against their tumors1,2
. However, such immune responses fail to provide complete protection against the development or recurrence of breast cancer. To overcome this problem by increasing the frequency of tumor-reactive T cells, adoptive immunotherapy has been employed. A variety of protocols have been used for the expansion of tumor-specific T cells. These protocols, however, are restricted to the use of tumor antigens ex vivo
for the activation of antigen-specific T cells. Very recently, common gamma chain cytokines such as IL-2, IL-7, IL-15, and IL-21 have been used alone or in combination for the enhancement of anti-tumor immune responses3
. However, it is not clear what formulation would work best for the expansion of tumor-reactive T cells. Here we present a protocol for the selective activation and expansion of tumor-reactive T cells from the FVBN202 transgenic mouse model of HER-2/neu positive breast carcinoma for use in adoptive T cell therapy of breast cancer. The protocol includes activation of T cells with bryostatin-1/ionomycin (B/I) and IL-2 in the absence of tumor antigens for 16 hours. B/I activation mimics intracellular signals that result in T cell activation by increasing protein kinase C activity and intracellular calcium, respectively4
. This protocol specifically activates tumor-specific T cells while killing irrelevant T cells. The B/I-activated T cells are cultured with IL-7 and IL-15 for 24 hours and then pulsed with IL-2. After 24 hours, T cells are washed, split, and cultured with IL-7 + IL-15 for additional 4 days. Tumor-specificity and anti-tumor efficacy of the ex vivo
expanded T cells is determined.
Immunology, Issue 47, Adoptive T cell therapy, Breast Cancer, HER-2/neu, common gamma chain cytokines, Bryostatin 1, Ionomycin
Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase
Institutions: Clemson University.
Acetate kinase, a member of the acetate and sugar kinase-Hsp70-actin (ASKHA) enzyme superfamily1-5
, is responsible for the reversible phosphorylation of acetate to acetyl phosphate utilizing ATP as a substrate. Acetate kinases are ubiquitous in the Bacteria
, found in one genus of Archaea
, and are also present in microbes of the Eukarya6
. The most well characterized acetate kinase is that from the methane-producing archaeon Methanosarcina thermophila7-14
. An acetate kinase which can only utilize PPi
but not ATP in the acetyl phosphate-forming direction has been isolated from Entamoeba histolytica
, the causative agent of amoebic dysentery, and has thus far only been found in this genus15,16
In the direction of acetyl phosphate formation, acetate kinase activity is typically measured using the hydroxamate assay, first described by Lipmann17-20
, a coupled assay in which conversion of ATP to ADP is coupled to oxidation of NADH to NAD+
by the enzymes pyruvate kinase and lactate dehydrogenase21,22
, or an assay measuring release of inorganic phosphate after reaction of the acetyl phosphate product with hydroxylamine23
. Activity in the opposite, acetate-forming direction is measured by coupling ATP formation from ADP to the reduction of NADP+
to NADPH by the enzymes hexokinase and glucose 6-phosphate dehydrogenase24
Here we describe a method for the detection of acetate kinase activity in the direction of acetate formation that does not require coupling enzymes, but is instead based on direct determination of acetyl phosphate consumption. After the enzymatic reaction, remaining acetyl phosphate is converted to a ferric hydroxamate complex that can be measured spectrophotometrically, as for the hydroxamate assay. Thus, unlike the standard coupled assay for this direction that is dependent on the production of ATP from ADP, this direct assay can be used for acetate kinases that produce ATP or PPi
Molecular Biology, Issue 58, Acetate kinase, acetate, acetyl phosphate, pyrophosphate, PPi, ATP
Polymalic Acid-based Nano Biopolymers for Targeting of Multiple Tumor Markers: An Opportunity for Personalized Medicine?
Institutions: Cedars-Sinai Medical Center.
Tumors with similar grade and morphology often respond differently to the same treatment because of variations in molecular profiling. To account for this diversity, personalized medicine is developed for silencing malignancy associated genes. Nano drugs fit these needs by targeting tumor and delivering antisense oligonucleotides for silencing of genes. As drugs for the treatment are often administered repeatedly, absence of toxicity and negligible immune response are desirable. In the example presented here, a nano medicine is synthesized from the biodegradable, non-toxic and non-immunogenic platform polymalic acid by controlled chemical ligation of antisense oligonucleotides and tumor targeting molecules. The synthesis and treatment is exemplified for human Her2-positive breast cancer using an experimental mouse model. The case can be translated towards synthesis and treatment of other tumors.
Chemistry, Issue 88, Cancer treatment, personalized medicine, polymalic acid, nanodrug, biopolymer, targeting, host compatibility, biodegradability
Analysis of Cell Migration within a Three-dimensional Collagen Matrix
Institutions: Witten/Herdecke University.
The ability to migrate is a hallmark of various cell types and plays a crucial role in several physiological processes, including embryonic development, wound healing, and immune responses. However, cell migration is also a key mechanism in cancer enabling these cancer cells to detach from the primary tumor to start metastatic spreading. Within the past years various cell migration assays have been developed to analyze the migratory behavior of different cell types. Because the locomotory behavior of cells markedly differs between a two-dimensional (2D) and three-dimensional (3D) environment it can be assumed that the analysis of the migration of cells that are embedded within a 3D environment would yield in more significant cell migration data. The advantage of the described 3D collagen matrix migration assay is that cells are embedded within a physiological 3D network of collagen fibers representing the major component of the extracellular matrix. Due to time-lapse video microscopy real cell migration is measured allowing the determination of several migration parameters as well as their alterations in response to pro-migratory factors or inhibitors. Various cell types could be analyzed using this technique, including lymphocytes/leukocytes, stem cells, and tumor cells. Likewise, also cell clusters or spheroids could be embedded within the collagen matrix concomitant with analysis of the emigration of single cells from the cell cluster/ spheroid into the collagen lattice. We conclude that the 3D collagen matrix migration assay is a versatile method to analyze the migration of cells within a physiological-like 3D environment.
Bioengineering, Issue 92, cell migration, 3D collagen matrix, cell tracking
Measuring Intracellular Ca2+ Changes in Human Sperm using Four Techniques: Conventional Fluorometry, Stopped Flow Fluorometry, Flow Cytometry and Single Cell Imaging
Institutions: Instituto de Biotecnología-Universidad Nacional Autónoma de México, Edison State College.
Spermatozoa are male reproductive cells especially designed to reach, recognize and fuse with the egg. To perform these tasks, sperm cells must be prepared to face a constantly changing environment and to overcome several physical barriers. Being in essence transcriptionally and translationally silent, these motile cells rely profoundly on diverse signaling mechanisms to orient themselves and swim in a directed fashion, and to contend with challenging environmental conditions during their journey to find the egg. In particular, Ca2+
-mediated signaling is pivotal for several sperm functions: activation of motility, capacitation (a complex process that prepares sperm for the acrosome reaction) and the acrosome reaction (an exocytotic event that allows sperm-egg fusion). The use of fluorescent dyes to track intracellular fluctuations of this ion is of remarkable importance due to their ease of application, sensitivity, and versatility of detection. Using one single dye-loading protocol we utilize four different fluorometric techniques to monitor sperm Ca2+
dynamics. Each technique provides distinct information that enables spatial and/or temporal resolution, generating data both at single cell and cell population levels.
Cellular Biology, Issue 75, Medicine, Molecular Biology, Genetics, Biophysics, Anatomy, Physiology, Spermatozoa, Ion Channels, Cell Physiological Processes, Calcium Signaling, Reproductive Physiological Processes, fluorometry, Flow cytometry, stopped flow fluorometry, single-cell imaging, human sperm, sperm physiology, intracellular Ca2+, Ca2+ signaling, Ca2+ imaging, fluorescent dyes, imaging
Modeling Astrocytoma Pathogenesis In Vitro and In Vivo Using Cortical Astrocytes or Neural Stem Cells from Conditional, Genetically Engineered Mice
Institutions: University of North Carolina School of Medicine, University of North Carolina School of Medicine, University of North Carolina School of Medicine, University of North Carolina School of Medicine, University of North Carolina School of Medicine, Emory University School of Medicine, University of North Carolina School of Medicine.
Current astrocytoma models are limited in their ability to define the roles of oncogenic mutations in specific brain cell types during disease pathogenesis and their utility for preclinical drug development. In order to design a better model system for these applications, phenotypically wild-type cortical astrocytes and neural stem cells (NSC) from conditional, genetically engineered mice (GEM) that harbor various combinations of floxed oncogenic alleles were harvested and grown in culture. Genetic recombination was induced in vitro
using adenoviral Cre-mediated recombination, resulting in expression of mutated oncogenes and deletion of tumor suppressor genes. The phenotypic consequences of these mutations were defined by measuring proliferation, transformation, and drug response in vitro
. Orthotopic allograft models, whereby transformed cells are stereotactically injected into the brains of immune-competent, syngeneic littermates, were developed to define the role of oncogenic mutations and cell type on tumorigenesis in vivo
. Unlike most established human glioblastoma cell line xenografts, injection of transformed GEM-derived cortical astrocytes into the brains of immune-competent littermates produced astrocytomas, including the most aggressive subtype, glioblastoma, that recapitulated the histopathological hallmarks of human astrocytomas, including diffuse invasion of normal brain parenchyma. Bioluminescence imaging of orthotopic allografts from transformed astrocytes engineered to express luciferase was utilized to monitor in vivo
tumor growth over time. Thus, astrocytoma models using astrocytes and NSC harvested from GEM with conditional oncogenic alleles provide an integrated system to study the genetics and cell biology of astrocytoma pathogenesis in vitro
and in vivo
and may be useful in preclinical drug development for these devastating diseases.
Neuroscience, Issue 90, astrocytoma, cortical astrocytes, genetically engineered mice, glioblastoma, neural stem cells, orthotopic allograft
Viability Assays for Cells in Culture
Institutions: Duquesne University.
Manual cell counts on a microscope are a sensitive means of assessing cellular viability but are time-consuming and therefore expensive. Computerized viability assays are expensive in terms of equipment but can be faster and more objective than manual cell counts. The present report describes the use of three such viability assays. Two of these assays are infrared and one is luminescent. Both infrared assays rely on a 16 bit Odyssey Imager. One infrared assay uses the DRAQ5 stain for nuclei combined with the Sapphire stain for cytosol and is visualized in the 700 nm channel. The other infrared assay, an In-Cell Western, uses antibodies against cytoskeletal proteins (α-tubulin or microtubule associated protein 2) and labels them in the 800 nm channel. The third viability assay is a commonly used luminescent assay for ATP, but we use a quarter of the recommended volume to save on cost. These measurements are all linear and correlate with the number of cells plated, but vary in sensitivity. All three assays circumvent time-consuming microscopy and sample the entire well, thereby reducing sampling error. Finally, all of the assays can easily be completed within one day of the end of the experiment, allowing greater numbers of experiments to be performed within short timeframes. However, they all rely on the assumption that cell numbers remain in proportion to signal strength after treatments, an assumption that is sometimes not met, especially for cellular ATP. Furthermore, if cells increase or decrease in size after treatment, this might affect signal strength without affecting cell number. We conclude that all viability assays, including manual counts, suffer from a number of caveats, but that computerized viability assays are well worth the initial investment. Using all three assays together yields a comprehensive view of cellular structure and function.
Cellular Biology, Issue 83, In-cell Western, DRAQ5, Sapphire, Cell Titer Glo, ATP, primary cortical neurons, toxicity, protection, N-acetyl cysteine, hormesis
Optimization and Utilization of Agrobacterium-mediated Transient Protein Production in Nicotiana
Institutions: Fraunhofer USA Center for Molecular Biotechnology.
-mediated transient protein production in plants is a promising approach to produce vaccine antigens and therapeutic proteins within a short period of time. However, this technology is only just beginning to be applied to large-scale production as many technological obstacles to scale up are now being overcome. Here, we demonstrate a simple and reproducible method for industrial-scale transient protein production based on vacuum infiltration of Nicotiana
plants with Agrobacteria
carrying launch vectors. Optimization of Agrobacterium
cultivation in AB medium allows direct dilution of the bacterial culture in Milli-Q water, simplifying the infiltration process. Among three tested species of Nicotiana
, N. excelsiana
× N. excelsior
) was selected as the most promising host due to the ease of infiltration, high level of reporter protein production, and about two-fold higher biomass production under controlled environmental conditions. Induction of Agrobacterium
harboring pBID4-GFP (Tobacco mosaic virus
-based) using chemicals such as acetosyringone and monosaccharide had no effect on the protein production level. Infiltrating plant under 50 to 100 mbar for 30 or 60 sec resulted in about 95% infiltration of plant leaf tissues. Infiltration with Agrobacterium
laboratory strain GV3101 showed the highest protein production compared to Agrobacteria
laboratory strains LBA4404 and C58C1 and wild-type Agrobacteria
strains at6, at10, at77 and A4. Co-expression of a viral RNA silencing suppressor, p23 or p19, in N. benthamiana
resulted in earlier accumulation and increased production (15-25%) of target protein (influenza virus hemagglutinin).
Plant Biology, Issue 86, Agroinfiltration, Nicotiana benthamiana, transient protein production, plant-based expression, viral vector, Agrobacteria
A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide
Institutions: Queen's University, Ask Science Products Inc..
In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. A variety of molecules, such as peptides or oligonucleotides can be introduced into essentially 100% of the cells in a non-traumatic manner. Here, we describe how it can be used to study intercellular, gap junctional communication. Lucifer yellow penetrates into the cells when an electric pulse, applied to the conductive surface on which they are growing, causes pores to form through the cell membrane. This is electroporation. Cells growing on the nonconductive glass surface immediately adjacent to the electroporated region do not take up Lucifer yellow by electroporation but do acquire the fluorescent dye as it is passed to them via gap junctions that link them to the electroporated cells. The results of the transfer of dye from cell to cell can be observed microscopically under fluorescence illumination. This technique allows for precise quantitation of gap junctional communication. In addition, it can be used for the introduction of peptides or other non-permeant molecules, and the transfer of small electroporated peptides via gap junctions to inhibit the signal in the adjacent, non-electroporated cells is a powerful demonstration of signal inhibition.
Molecular Biology, Issue 92, Electroporation, Indium-Tin oxide, signal transduction, gap junctional communication, peptides, Stat3
The Fastest Western in Town: A Contemporary Twist on the Classic Western Blot Analysis
Institutions: University of California, San Francisco.
The Western blot techniques that were originally established in the late 1970s are still actively utilized today. However, this traditional method of Western blotting has several drawbacks that include low quality resolution, spurious bands, decreased sensitivity, and poor protein integrity. Recent advances have drastically improved numerous aspects of the standard Western blot protocol to produce higher qualitative and quantitative data. The Bis-Tris gel system, an alternative to the conventional Laemmli system, generates better protein separation and resolution, maintains protein integrity, and reduces electrophoresis to a 35 min run time. Moreover, the iBlot dry blotting system, dramatically improves the efficacy and speed of protein transfer to the membrane in 7 min, which is in contrast to the traditional protein transfer methods that are often more inefficient with lengthy transfer times. In combination with these highly innovative modifications, protein detection using infrared fluorescent imaging results in higher-quality, more accurate and consistent data compared to the standard Western blotting technique of chemiluminescence. This technology can simultaneously detect two different antigens on the same membrane by utilizing two-color near-infrared dyes that are visualized in different fluorescent channels. Furthermore, the linearity and broad dynamic range of fluorescent imaging allows for the precise quantification of both strong and weak protein bands. Thus, this protocol describes the key improvements to the classic Western blotting method, in which these advancements significantly increase the quality of data while greatly reducing the performance time of this experiment.
Basic Protocol, Issue 84, Western blot, Bis-Tris, electrophoresis, dry blotting, protein transfer, infrared, Fluorescence, quantification, Antibody, Protein
Depletion of Specific Cell Populations by Complement Depletion
Institutions: Blood Research Institute.
The purification of immune cell populations is often required in order to study their unique functions. In particular, molecular approaches such as real-time PCR and microarray analysis require the isolation of cell populations with high purity. Commonly used purification strategies include fluorescent activated cell sorting (FACS), magnetic bead separation and complement depletion. Of the three strategies, complement depletion offers the advantages of being fast, inexpensive, gentle on the cells and a high cell yield. The complement system is composed of a large number of plasma proteins that when activated initiate a proteolytic cascade culminating in the formation of a membrane-attack complex that forms a pore on a cell surface resulting in cell death1
. The classical pathway is activated by IgM and IgG antibodies and was first described as a mechanism for killing bacteria. With the generation of monoclonal antibodies (mAb), the complement cascade can be used to lyse any cell population in an antigen-specific manner. Depletion of cells by the complement cascade is achieved by the addition of complement fixing antigen-specific antibodies and rabbit complement to the starting cell population. The cells are incubated for one hour at 37°C and the lysed cells are subsequently removed by two rounds of washing. MAb with a high efficiency for complement fixation typically deplete 95-100% of the targeted cell population. Depending on the purification strategy for the targeted cell population, complement depletion can be used for cell purification or for the enrichment of cell populations that then can be further purified by a subsequent method.
JoVE Immunology, Issue 36, rabbit, complement, cell isolation, cell depletion
Retroviral Transduction of T-cell Receptors in Mouse T-cells
Institutions: New York University School of Medicine, New York University School of Medicine.
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.
Immunology, Issue 44, T-cell, T-cell receptor, Retrovirus, Mouse, Transduction, Spleen
Preparation of Quality Inositol Pyrophosphates
Institutions: University College London.
Myo-inositol is present in nature either unmodified or in more complex phosphorylated derivates. Of the latest, the two most abundant in eukaryotic cells are inositol pentakisphosphate (IP5
) and inositol hexakisphosphate (phytic acid or IP6
are the precursors of inositol pyrophosphate molecules that contain one or more pyrophosphate bonds1
. Phosphorylation of IP6
generates diphoshoinositolpentakisphosphate (IP7
) and bisdiphoshoinositoltetrakisphosphate (IP8
). Inositol pyrophosphates have been isolated from all eukaryotic organisms so far studied. In addition, the two distinct classes of enzymes responsible for inositol pyrophosphate synthesis are highly conserved throughout evolution2-4
Ks) posses an enormous catalytic flexibility, converting IP5
respectively and subsequently, by using these products as substrates, promote the generation of more complex molecules5,6
. Recently, a second class of pyrophosphate generating enzymes was identified in the form of the yeast protein VIP1
(also referred as PP-IP5
K), which is able to convert IP6
Inositol pyrophosphates regulate many disparate cellular processes such as insulin secretion9
, telomere length10,11
, vesicular trafficking13
, phosphate homeostasis14
and HIV-1 gag release15
. Two mechanisms of actions have been proposed for this class of molecules. They can affect cellular function by allosterically interacting with specific proteins like AKT16
. Alternatively, the pyrophosphate group can donate a phosphate to pre-phosphorylated proteins17
. The enormous potential of this research field is hampered by the absence of a commercial source of inositol pyrophosphates, which is preventing many scientists from studying these molecules and this new post-translational modification. The methods currently available to isolate inositol pyrophosphates require sophisticated chromatographic apparatus18,19
. These procedures use acidic conditions that might lead to inositol pyrophosphate degradation20
and thus to poor recovery. Furthermore, the cumbersome post-column desalting procedures restrict their use to specialized laboratories.
In this study we describe an undemanding method for the generation, isolation and purification of the products of the IP6
-kinase and PP-IP5
-kinases reactions. This method was possible by the ability of polyacrylamide gel electrophoresis (PAGE) to resolve highly phosphorylated inositol polyphosphates20
. Following IP6
K1 and PP-IP5
K enzymatic reactions using IP6
as the substrate, PAGE was used to separate the generated inositol pyrophosphates that were subsequently eluted in water.
Molecular Biology, Issue 55, Polyacrilamyde Gel Electrophoresis (PAGE), inositol hexakisphosphate (IP6), phytic acid, diphosphoinositol pentakisphosphate (IP7), bisdiphoshoinositol tetrakisphosphate (IP8), IP6-kinase (IP6K), PP-IP5K, VIP1
Examination of Thymic Positive and Negative Selection by Flow Cytometry
Institutions: University of Alberta.
A healthy immune system requires that T cells respond to foreign antigens while remaining tolerant to self-antigens. Random rearrangement of the T cell receptor (TCR) α and β loci generates a T cell repertoire with vast diversity in antigen specificity, both to self and foreign. Selection of the repertoire during development in the thymus is critical for generating safe and useful T cells. Defects in thymic selection contribute to the development of autoimmune and immunodeficiency disorders1-4
T cell progenitors enter the thymus as double negative (DN) thymocytes that do not express CD4 or CD8 co-receptors. Expression of the αβTCR and both co-receptors occurs at the double positive (DP) stage. Interaction of the αβTCR with self-peptide-MHC (pMHC) presented by thymic cells determines the fate of the DP thymocyte. High affinity interactions lead to negative selection and elimination of self-reactive thymocytes. Low affinity interactions result in positive selection and development of CD4 or CD8 single positive (SP) T cells capable of recognizing foreign antigens presented by self-MHC5
Positive selection can be studied in mice with a polyclonal (wildtype) TCR repertoire by observing the generation of mature T cells. However, they are not ideal for the study of negative selection, which involves deletion of small antigen-specific populations. Many model systems have been used to study negative selection but vary in their ability to recapitulate physiological events6
. For example, in vitro
stimulation of thymocytes lacks the thymic environment that is intimately involved in selection, while administration of exogenous antigen can lead to non-specific deletion of thymocytes7-9
. Currently, the best tools for studying in vivo
negative selection are mice that express a transgenic TCR specific for endogenous self-antigen. However, many classical TCR transgenic models are characterized by premature expression of the transgenic TCRα chain at the DN stage, resulting in premature negative selection. Our lab has developed the HYcd4
model, in which the transgenic HY TCRα is conditionally expressed at the DP stage, allowing negative selection to occur during the DP to SP transition as occurs in wildtype mice10
Here, we describe a flow cytometry-based protocol to examine thymic positive and negative selection in the HYcd4
mouse model. While negative selection in HYcd4
mice is highly physiological, these methods can also be applied to other TCR transgenic models. We will also present general strategies for analyzing positive selection in a polyclonal repertoire applicable to any genetically manipulated mice.
Immunology, Issue 68, Medicine, Cellular Biology, Anatomy, Physiology, Thymus, T cell, negative selection, positive selection, autoimmunity, flow cytometry
Artificial Antigen Presenting Cell (aAPC) Mediated Activation and Expansion of Natural Killer T Cells
Institutions: University of Maryland .
Natural killer T (NKT) cells are a unique subset of T cells that display markers characteristic of both natural killer (NK) cells and T cells1
. Unlike classical T cells, NKT cells recognize lipid antigen in the context of CD1 molecules2
. NKT cells express an invariant TCRα chain rearrangement: Vα14Jα18 in mice and Vα24Jα18 in humans, which is associated with Vβ chains of limited diversity3-6
, and are referred to as canonical or invariant NKT (i
NKT) cells. Similar to conventional T cells, NKT cells develop from CD4-CD8- thymic precursor T cells following the appropriate signaling by CD1d 7
. The potential to utilize NKT cells for therapeutic purposes has significantly increased with the ability to stimulate and expand human NKT cells with α-Galactosylceramide (α-GalCer) and a variety of cytokines8
. Importantly, these cells retained their original phenotype, secreted cytokines, and displayed cytotoxic function against tumor cell lines. Thus, ex vivo
expanded NKT cells remain functional and can be used for adoptive immunotherapy. However, NKT cell based-immunotherapy has been limited by the use of autologous antigen presenting cells and the quantity and quality of these stimulator cells can vary substantially. Monocyte-derived DC from cancer patients have been reported to express reduced levels of costimulatory molecules and produce less inflammatory cytokines9,10
. In fact, murine DC rather than autologous APC have been used to test the function of NKT cells from CML patients11
. However, this system can only be used for in vitro
testing since NKT cells cannot be expanded by murine DC and then used for adoptive immunotherapy. Thus, a standardized system that relies on artificial Antigen Presenting Cells (aAPC) could produce the stimulating effects of DC without the pitfalls of allo- or xenogeneic cells12, 13
. Herein, we describe a method for generating CD1d-based aAPC. Since the engagement of the T cell receptor (TCR) by CD1d-antigen complexes is a fundamental requirement of NKT cell activation, antigen: CD1d-Ig complexes provide a reliable method to isolate, activate, and expand effector NKT cell populations.
Immunology, Issue 70, Medicine, Molecular Biology, Cellular Biology, Microbiology, Cancer Biology, Natural killer T cells, in vitro expansion, cancer immunology, artificial antigen presenting cells, adoptive transfer
Directed Differentiation of Induced Pluripotent Stem Cells towards T Lymphocytes
Institutions: Pennsylvania State University College of Medicine.
Adoptive cell transfer (ACT) of antigen-specific CD8+
cytotoxic T lymphocytes (CTLs) is a promising treatment for a variety of malignancies 1
. CTLs can recognize malignant cells by interacting tumor antigens with the T cell receptors (TCR), and release cytotoxins as well as cytokines to kill malignant cells. It is known that less-differentiated and central-memory-like (termed highly reactive
) CTLs are the optimal population for ACT-based immunotherapy, because these CTLs have a high proliferative potential, are less prone to apoptosis than more differentiated cells and have a higher ability to respond to homeostatic cytokines 2-7
. However, due to difficulties in obtaining a high number of such CTLs from patients, there is an urgent need to find a new approach to generate highly reactive Ag-specific CTLs for successful ACT-based therapies.
TCR transduction of the self-renewable stem cells for immune reconstitution has a therapeutic potential for the treatment of diseases 8-10
. However, the approach to obtain embryonic stem cells (ESCs) from patients is not feasible. Although the use of hematopoietic stem cells (HSCs) for therapeutic purposes has been widely applied in clinic 11-13
, HSCs have reduced differentiation and proliferative capacities, and HSCs are difficult to expand in in vitro
cell culture 14-16
. Recent iPS cell technology and the development of an in vitro
system for gene delivery are capable of generating iPS cells from patients without any surgical approach. In addition, like ESCs, iPS cells possess indefinite proliferative capacity in vitro
, and have been shown to differentiate into hematopoietic cells. Thus, iPS cells have greater potential to be used in ACT-based immunotherapy compared to ESCs or HSCs.
Here, we present methods for the generation of T lymphocytes from iPS cells in vitro
, and in vivo
programming of antigen-specific CTLs from iPS cells for promoting cancer immune surveillance. Stimulation in vitro
with a Notch ligand drives T cell differentiation from iPS cells, and TCR gene transduction results in iPS cells differentiating into antigen-specific T cells in vivo
, which prevents tumor growth. Thus, we demonstrate antigen-specific T cell differentiation from iPS cells. Our studies provide a potentially more efficient approach for generating antigen-specific CTLs for ACT-based therapies and facilitate the development of therapeutic strategies for diseases.
Stem Cell Biology, Issue 63, Immunology, T cells, induced pluripotent stem cells, differentiation, Notch signaling, T cell receptor, adoptive cell transfer
Setting-up an In Vitro Model of Rat Blood-brain Barrier (BBB): A Focus on BBB Impermeability and Receptor-mediated Transport
Institutions: VECT-HORUS SAS, CNRS, NICN UMR 7259.
The blood brain barrier (BBB) specifically regulates molecular and cellular flux between the blood and the nervous tissue. Our aim was to develop and characterize a highly reproducible rat syngeneic in vitro
model of the BBB using co-cultures of primary rat brain endothelial cells (RBEC) and astrocytes to study receptors involved in transcytosis across the endothelial cell monolayer. Astrocytes were isolated by mechanical dissection following trypsin digestion and were frozen for later co-culture. RBEC were isolated from 5-week-old rat cortices. The brains were cleaned of meninges and white matter, and mechanically dissociated following enzymatic digestion. Thereafter, the tissue homogenate was centrifuged in bovine serum albumin to separate vessel fragments from nervous tissue. The vessel fragments underwent a second enzymatic digestion to free endothelial cells from their extracellular matrix. The remaining contaminating cells such as pericytes were further eliminated by plating the microvessel fragments in puromycin-containing medium. They were then passaged onto filters for co-culture with astrocytes grown on the bottom of the wells. RBEC expressed high levels of tight junction (TJ) proteins such as occludin, claudin-5 and ZO-1 with a typical localization at the cell borders. The transendothelial electrical resistance (TEER) of brain endothelial monolayers, indicating the tightness of TJs reached 300 ohm·cm2
on average. The endothelial permeability coefficients (Pe) for lucifer yellow (LY) was highly reproducible with an average of 0.26 ± 0.11 x 10-3
cm/min. Brain endothelial cells organized in monolayers expressed the efflux transporter P-glycoprotein (P-gp), showed a polarized transport of rhodamine 123, a ligand for P-gp, and showed specific transport of transferrin-Cy3 and DiILDL across the endothelial cell monolayer. In conclusion, we provide a protocol for setting up an in vitro
BBB model that is highly reproducible due to the quality assurance methods, and that is suitable for research on BBB transporters and receptors.
Medicine, Issue 88, rat brain endothelial cells (RBEC), mouse, spinal cord, tight junction (TJ), receptor-mediated transport (RMT), low density lipoprotein (LDL), LDLR, transferrin, TfR, P-glycoprotein (P-gp), transendothelial electrical resistance (TEER),
Adenoviral Transduction of Naive CD4 T Cells to Study Treg Differentiation
Institutions: Helmholtz Zentrum München.
Regulatory T cells (Tregs) are essential to provide immune tolerance to self as well as to certain foreign antigens. Tregs can be generated from naive CD4 T cells in vitro
with TCR- and co-stimulation in the presence of TGFβ and IL-2. This bears enormous potential for future therapies, however, the molecules and signaling pathways that control differentiation are largely unknown.
Primary T cells can be manipulated through ectopic gene expression, but common methods fail to target the most important naive state of the T cell prior to primary antigen recognition. Here, we provide a protocol to express ectopic genes in naive CD4 T cells in vitro
before inducing Treg differentiation. It applies transduction with the replication-deficient adenovirus and explains its generation and production. The adenovirus can take up large inserts (up to 7 kb) and can be equipped with promoters to achieve high and transient overexpression in T cells. It effectively transduces naive mouse T cells if they express a transgenic Coxsackie adenovirus receptor (CAR). Importantly, after infection the T cells remain naive (CD44low
) and resting (CD25-
) and can be activated and differentiated into Tregs similar to non-infected cells. Thus, this method enables manipulation of CD4 T cell differentiation from its very beginning. It ensures that ectopic gene expression is already in place when early signaling events of the initial TCR stimulation induces cellular changes that eventually lead into Treg differentiation.
Immunology, Issue 78, Cellular Biology, Molecular Biology, Medicine, Biomedical Engineering, Bioengineering, Infection, Genetics, Microbiology, Virology, T-Lymphocytes, Regulatory, CD4-Positive T-Lymphocytes, Regulatory, Adenoviruses, Human, MicroRNAs, Antigens, Differentiation, T-Lymphocyte, Gene Transfer Techniques, Transduction, Genetic, Transfection, Adenovirus, gene transfer, microRNA, overexpression, knock down, CD4 T cells, in vitro differentiation, regulatory T cell, virus, cell, flow cytometry
Generation of Human Alloantigen-specific T Cells from Peripheral Blood
Institutions: University of California, San Diego.
The study of human T lymphocyte biology often involves examination of responses to activating ligands. T cells recognize and respond to processed peptide antigens presented by MHC (human ortholog HLA) molecules through the T cell receptor (TCR) in a highly sensitive and specific manner. While the primary function of T cells is to mediate protective immune responses to foreign antigens presented by self-MHC, T cells respond robustly to antigenic differences in allogeneic tissues. T cell responses to alloantigens can be described as either direct or indirect alloreactivity. In alloreactivity, the T cell responds through highly specific recognition of both the presented peptide and the MHC molecule. The robust oligoclonal response of T cells to allogeneic stimulation reflects the large number of potentially stimulatory alloantigens present in allogeneic tissues. While the breadth of alloreactive T cell responses is an important factor in initiating and mediating the pathology associated with biologically-relevant alloreactive responses such as graft versus host disease and allograft rejection, it can preclude analysis of T cell responses to allogeneic ligands. To this end, this protocol describes a method for generating alloreactive T cells from naive human peripheral blood leukocytes (PBL) that respond to known peptide-MHC (pMHC) alloantigens. The protocol applies pMHC multimer labeling, magnetic bead enrichment and flow cytometry to single cell in vitro
culture methods for the generation of alloantigen-specific T cell clones. This enables studies of the biochemistry and function of T cells responding to allogeneic stimulation.
Immunology, Issue 93, T cell, immunology, human cell culture, transplantation, flow cytometry, alloreactivity
Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1β in Human Monocyte-derived Dendritic Cells
Institutions: New York University School of Medicine, Mount Sinai Medical Center, Mount Sinai Medical Center.
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-1β 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-1β secretion6
. Pro-IL-1β protein expression is limited in resting cells; therefore a priming signal is required for IL-1β 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-1β secretion can be tested using a synthetic purine, R848, which is sensed by TLR8 in human monocyte derived dendritic cells (moDCs) to prime cells, followed by activation of the NLRP3 inflammasome with the bacterial toxin and potassium ionophore, nigericin.
Monocyte derived DCs 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.
Immunology, Issue 87, NLRP3, inflammasome, IL-1beta, Interleukin-1 beta, dendritic, cell, Nigericin, Toll-Like Receptor 8, TLR8, R848, Monocyte Derived Dendritic Cells
Protein WISDOM: A Workbench for In silico De novo Design of BioMolecules
Institutions: Princeton University.
The aim of de novo
protein design is to find the amino acid sequences that will fold into a desired 3-dimensional structure with improvements in specific properties, such as binding affinity, agonist or antagonist behavior, or stability, relative to the native sequence. Protein design lies at the center of current advances drug design and discovery. Not only does protein design provide predictions for potentially useful drug targets, but it also enhances our understanding of the protein folding process and protein-protein interactions. Experimental methods such as directed evolution have shown success in protein design. However, such methods are restricted by the limited sequence space that can be searched tractably. In contrast, computational design strategies allow for the screening of a much larger set of sequences covering a wide variety of properties and functionality. We have developed a range of computational de novo
protein design methods capable of tackling several important areas of protein design. These include the design of monomeric proteins for increased stability and complexes for increased binding affinity.
To disseminate these methods for broader use we present Protein WISDOM (http://www.proteinwisdom.org), a tool that provides automated methods for a variety of protein design problems. Structural templates are submitted to initialize the design process. The first stage of design is an optimization sequence selection stage that aims at improving stability through minimization of potential energy in the sequence space. Selected sequences are then run through a fold specificity stage and a binding affinity stage. A rank-ordered list of the sequences for each step of the process, along with relevant designed structures, provides the user with a comprehensive quantitative assessment of the design. Here we provide the details of each design method, as well as several notable experimental successes attained through the use of the methods.
Genetics, Issue 77, Molecular Biology, Bioengineering, Biochemistry, Biomedical Engineering, Chemical Engineering, Computational Biology, Genomics, Proteomics, Protein, Protein Binding, Computational Biology, Drug Design, optimization (mathematics), Amino Acids, Peptides, and Proteins, De novo protein and peptide design, Drug design, In silico sequence selection, Optimization, Fold specificity, Binding affinity, sequencing
High Efficiency Differentiation of Human Pluripotent Stem Cells to Cardiomyocytes and Characterization by Flow Cytometry
Institutions: Medical College of Wisconsin, Stanford University School of Medicine, Medical College of Wisconsin, Hong Kong University, Johns Hopkins University School of Medicine, Medical College of Wisconsin.
There is an urgent need to develop approaches for repairing the damaged heart, discovering new therapeutic drugs that do not have toxic effects on the heart, and improving strategies to accurately model heart disease. The potential of exploiting human induced pluripotent stem cell (hiPSC) technology to generate cardiac muscle “in a dish” for these applications continues to generate high enthusiasm. In recent years, the ability to efficiently generate cardiomyogenic cells from human pluripotent stem cells (hPSCs) has greatly improved, offering us new opportunities to model very early stages of human cardiac development not otherwise accessible. In contrast to many previous methods, the cardiomyocyte differentiation protocol described here does not require cell aggregation or the addition of Activin A or BMP4 and robustly generates cultures of cells that are highly positive for cardiac troponin I and T (TNNI3, TNNT2), iroquois-class homeodomain protein IRX-4 (IRX4), myosin regulatory light chain 2, ventricular/cardiac muscle isoform (MLC2v) and myosin regulatory light chain 2, atrial isoform (MLC2a) by day 10 across all human embryonic stem cell (hESC) and hiPSC lines tested to date. Cells can be passaged and maintained for more than 90 days in culture. The strategy is technically simple to implement and cost-effective. Characterization of cardiomyocytes derived from pluripotent cells often includes the analysis of reference markers, both at the mRNA and protein level. For protein analysis, flow cytometry is a powerful analytical tool for assessing quality of cells in culture and determining subpopulation homogeneity. However, technical variation in sample preparation can significantly affect quality of flow cytometry data. Thus, standardization of staining protocols should facilitate comparisons among various differentiation strategies. Accordingly, optimized staining protocols for the analysis of IRX4, MLC2v, MLC2a, TNNI3, and TNNT2 by flow cytometry are described.
Cellular Biology, Issue 91, human induced pluripotent stem cell, flow cytometry, directed differentiation, cardiomyocyte, IRX4, TNNI3, TNNT2, MCL2v, MLC2a
Live Imaging of Drug Responses in the Tumor Microenvironment in Mouse Models of Breast Cancer
Institutions: Watson School of Biological Sciences, Cold Spring Harbor Laboratory, University of Oslo and Oslo University Hospital.
The tumor microenvironment plays a pivotal role in tumor initiation, progression, metastasis, and the response to anti-cancer therapies. Three-dimensional co-culture systems are frequently used to explicate tumor-stroma interactions, including their role in drug responses. However, many of the interactions that occur in vivo
in the intact microenvironment cannot be completely replicated in these in vitro
settings. Thus, direct visualization of these processes in real-time has become an important tool in understanding tumor responses to therapies and identifying the interactions between cancer cells and the stroma that can influence these responses. Here we provide a method for using spinning disk confocal microscopy of live, anesthetized mice to directly observe drug distribution, cancer cell responses and changes in tumor-stroma interactions following administration of systemic therapy in breast cancer models. We describe procedures for labeling different tumor components, treatment of animals for observing therapeutic responses, and the surgical procedure for exposing tumor tissues for imaging up to 40 hours. The results obtained from this protocol are time-lapse movies, in which such processes as drug infiltration, cancer cell death and stromal cell migration can be evaluated using image analysis software.
Cancer Biology, Issue 73, Medicine, Molecular Biology, Cellular Biology, Biomedical Engineering, Genetics, Oncology, Pharmacology, Surgery, Tumor Microenvironment, Intravital imaging, chemotherapy, Breast cancer, time-lapse, mouse models, cancer cell death, stromal cell migration, cancer, imaging, transgenic, animal model
Interview: Glycolipid Antigen Presentation by CD1d and the Therapeutic Potential of NKT cell Activation
Institutions: La Jolla Institute for Allergy and Immunology.
Natural Killer T cells (NKT) are critical determinants of the immune response to cancer, regulation of autioimmune disease, clearance of infectious agents, and the development of artheriosclerotic plaques. In this interview, Mitch Kronenberg discusses his laboratory's efforts to understand the mechanism through which NKT cells are activated by glycolipid antigens. Central to these studies is CD1d - the antigen presenting molecule that presents glycolipids to NKT cells. The advent of CD1d tetramer technology, a technique developed by the Kronenberg lab, is critical for the sorting and identification of subsets of specific glycolipid-reactive T cells. Mitch explains how glycolipid agonists are being used as therapeutic agents to activate NKT cells in cancer patients and how CD1d tetramers can be used to assess the state of the NKT cell population in vivo following glycolipid agonist therapy. Current status of ongoing clinical trials using these agonists are discussed as well as Mitch's prediction for areas in the field of immunology that will have emerging importance in the near future.
Immunology, Issue 10, Natural Killer T cells, NKT cells, CD1 Tetramers, antigen presentation, glycolipid antigens, CD1d, Mucosal Immunity, Translational Research