An Endothelial Planar Cell Model for Imaging Immunological Synapse Dynamics

Summary

Adaptive immunity is controlled by dynamic 'immunological synapses' formed between T cells and antigen presenting cells. This protocol describes methods for investigating endothelial cells both as understudied physiologic APCs and as a novel type of 'planar cellular APC model'.

Abstract

Adaptive immunity is regulated by dynamic interactions between T cells and antigen presenting cells ('APCs') referred to as 'immunological synapses'. Within these intimate cell-cell interfaces discrete sub-cellular clusters of MHC/Ag-TCR, F-actin, adhesion and signaling molecules form and remodel rapidly. These dynamics are thought to be critical determinants of both the efficiency and quality of the immune responses that develop and therefore of protective versus pathologic immunity. Current understanding of immunological synapses with physiologic APCs is limited by the inadequacy of the obtainable imaging resolution. Though artificial substrate models (e.g., planar lipid bilayers) offer excellent resolution and have been extremely valuable tools, they are inherently non-physiologic and oversimplified. Vascular and lymphatic endothelial cells have emerged as an important peripheral tissue (or stromal) compartment of 'semi-professional APCs'. These APCs (which express most of the molecular machinery of professional APCs) have the unique feature of forming virtually planar cell surface and are readily transfectable (e.g., with fluorescent protein reporters). Herein a basic approach to implement endothelial cells as a novel and physiologic 'planar cellular APC model' for improved imaging and interrogation of fundamental antigenic signaling processes will be described.

Introduction

T lymphocytes are a branch of the adaptive immune system characterized by the ability to efficiently recognize peptide antigen (Ag) bound to major histocompatibility complex (MHC) molecules through their T cell receptors (TCRs) ¹. Naïve lymphocytes constitutively migrate and scan 'professional Ag presenting cells' (APCs; e.g., dendritic cells) within lymph nodes, while memory/effector T cells need to effectively survey an extremely wide range of APCs and potential target cells within peripheral tissues.

In the min following initial recognition of cognate Ag on an APC, lymphocytes arrest their migration and begin to form ....

Protocol

All experiments described in this protocol are conducted with primary human T cells and commercially available primary human endothelial cells (dermal or lung microvascular ECs).Any research protocol involving human subjects must be approved by an institutional review board and written informed consent must be provided from each blood donor. Experiments conducted using this protocol were approved by the IRB of Beth Israel Deaconess Medical Center.

1. Preparing Human CD4⁺ Th1 Effector/Memory T Cells

1. Apply tourniquet to the arm of donor, wipe vein with alcohol, and insert needle. Slowly draw 15 ml of blood into vacutainer using EDTA as anti....

Results

A novel imaging approach using endothelial cells and combining the resolution advantages of the planar lipid bilayers model with the physiologic complexity and deformability of professional APCs was developed (Figure 1). Figure 2 provides examples of typical migration, calcium flux and topological dynamics observed with this approach. In the absence of SAg on endothelium, SAg-specific CD4⁺ Th1 lymphocytes rapidly spread, polarize and laterally .......

Discussion

Overall, this protocol describes methods for investigating endothelial cells as i) understudied physiologic APCs and ii) as a novel type of 'planar cellular APC model'. With respect to the former, it has become increasingly appreciated that non-hematopoietic peripheral (or 'stromal') APCs play critical, non-redundant roles (i.e., compared to hematopoietic APCs) in shaping adaptive immune responses ^16-18. Among such 'semi-professional' APCs, vascular and lymphatic endothelial ce.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
BD Vacutainer stretch latex free tourniquet	BD Biosciences	367203
BD alcohol swabs	BD Biosciences	326895
BD Vacutainer Safety-Lok	BD Biosciences	367861	K2 EDTA
BD Vacutainer Push Button Blood Collection Set	BD Biosciences	367335
RPMI-1640	Sigma-Aldrich	R8758-1L
Ficoll-Paque	Sigma-Aldrich	GE17-1440-02	Bring to RT before use
FCS-Optima	Atlanta Biologics	s12450	Heat inactivated
Penicillin-Streptomycin	Sigma-Aldrich	P4458-100ML
Trypan blue	Sigma-Aldrich	T8154-20ML
staphylococcal enterotoxin B	Toxin Technology	BT202RED	Stock solution 1mg/ml in PBS
toxic shock syndrome toxin 1	Toxin Technology	TT606RED	Stock solution 1mg/ml in PBS
human IL-15	R&D Systems	247-IL-025	Stock solution 50ug/ml in PBS
PBS	Life Technologies	10010-049
Fibronectin	Life Technologies	33016-015	Stock solution 1mg/ml in H20
HMVEC-d Ad-Dermal MV Endo Cells	Lonza	CC-2543	Other Human Microvascular ECs can be used, i.e. HLMVECs
EGM-2 MV bullet kit	Lonza	CC-3202
Trypsin-EDTA	Sigma-Aldrich	T-4174	Stock solution 10x, dilute in PBS
amaxa-HMVEC-L Nucleofector Kit	Lonza	vpb1003	Required Kit for step 4
IFN-g	Sigma-Aldrich	I3265	Stock solution 1mg/ml in H20
TNF-alpha 10ug, human	Life Technologies	PHC3015	Stock solution 1mg/ml in H20
phenol Red-free HBSS	Life Technologies	14175-103
Hepes	Fisher Scientific	BP299-100
Calcium Chloride	Sigma-Aldrich	C1016-100G	Stock solution 1M in H20
Magnesium chloride	Sigma-Aldrich	208337	Stock solution 1M in H20
Human Serum albumin	Sigma-Aldrich	A6909-10ml
Immersol 518 F fluorescence free Immersion oil	Fisher Scientific	12-624-66A
Fura-2 AM 20x50ug	Life Technologies	F1221	Stock solution 1mM in DMSO
pEYFP-Mem (Mem-YFP)	Clontech	6917-1
pDsRed-Monomer (Soluble Cytoplasmic DsRed)	Clontech	632466
pDsRed-Monomer Membrane (Mem-DsRed)	Clontech	632512
pEGFP-Actin	Clontech	6116-1
Alexa Fluor 488 Phalloidin	Life Technologies	A12379
Formaldehyde solution 37%	Fisher Scientific	BP531-500	Toxic, use fumehood
Triton X-100	Sigma-Aldrich	X100-5ML
Falcon 15mL Conical Centrifuge Tubes	Fisher Scientific	14-959-70C
Falcon 50mL Conical Centrifuge Tubes	Fisher Scientific	14-959-49A
Falcon Tissue Culture Treated Flasks T25	Fisher Scientific	10-126-9
Falcon Tissue Culture Treated Flasks T75	Fisher Scientific	13-680-65
Corning Cell Culture Treated T175	Fisher Scientific	10-126-61
Glass coverslips	Fisher Scientific	12-545-85	12 mm diameter
Falcon Tissue Culture Plates 24-well	Fisher Scientific	08-772-1
Delta-T plates	Bioptechs	04200415B
Wheaton Disposable Pasteur Pipets	Fisher Scientific	13-678-8D
1.5 ml Eppendorf tube	Fisher Scientific	05-402-25
ICAM1 mouse anti-human	BD Biosciences	555509
HS1 mouse anti-human	BD Biosciences	610541
Anti-Human CD11a (LFA-1alpha) Purified	ebioscience	BMS102
Anti-Human CD3 Alexa Fluor® 488	ebioscience	53-0037-41
Anti-MHC Class II antibody	Abcam	ab55152
Anti-Talin 1 antibody	Abcam	ab71333
Anti-PKC theta antibody	Abcam	ab109481
phosphotyrosine (4G10 Platinum)	Millipore	50-171-463
Nucleofector II	Amaxa Biosystems		Required electroporator for step 4
Zeiss Axiovert	Carl Zeiss MicroImaging
Zeiss LSM510	Carl Zeiss MicroImaging
Zeiss Axiovison Software	Carl Zeiss MicroImaging
NU-425 (Series 60) Biological Safety Cabinet	NuAIRE	Nu-425-600
Forma STRCYCLE 37 °C, 5% CO2 Cell culture Incubator	Fisher Scientific	202370
Centrifuge 5810	Eppendorf	EW-02570-02
Hemocytometer	Sigma-Aldrich	Z359629	Bright-Line Hemocytometer
Isotemp Waterbath model 202	Fisher Scientific	15-462-2