Adenoviral Transduction of Naive CD4 T Cells to Study Treg Differentiation

Summary

Adenoviral gene transfer into naive CD4 T cells with transgenic expression of the Coxsackie adenovirus receptor enables the molecular analysis of regulatory T cell differentiation in vitro.

Abstract

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 (CD44^low, CD62L^high) and resting (CD25^-, CD69^-) 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.

Introduction

Tregs are crucial to maintain immune tolerance and to dampen overshooting immune responses. Tregs suppress bystander T cell activation. Consequently, ablation of Tregs leads to fatal autoimmunity and self-destruction driven by activated T cells¹. Tregs develop in the thymus during negative selection of CD4 single-positive precursors, but they can also differentiate in the periphery from naive CD4 T cells upon low-dose antigen stimulation with suboptimal co-stimulation ^1,2. Thymic Tregs seem to suppress tissue autoimmunity against self-antigens, whereas peripheral Tregs have been implicated in providing tolerance in the gut or lung. These induced ....

Protocol

1. Cloning of a Gene of Interest into an Entry Vector

1. Clone the gene of interest into an entry vector. PCR amplification of the gene followed by blunt-end ligation into a topoisomerase-coupled vector (e.g. pENTR/D-TOPO) or restriction enzyme-mediated cloning may be used for this procedure.

2. Transferring the Gene of Interest into the pCAGAdDu Destination Vector

1. Transfer the gene of interest from the entry vector into the destination vector by LR recombination (e.g. Gateway LR Clonase II Enzyme Mix). This will create the adenoviral expression vector (Figure 1).
2. Line....

Results

Virus Production

For generation of high virus titers, the timing of HEK293A cell harvest in primary virus production or virus amplification is crucial. Representative fluorescent and phase contrast images with visual signs of virus production are shown in Figure 3. The CPE were observed 10 days after transfection of HEK293A cells with a control pCAGAdDu vector without insert. CPE are characterized by the appearance of areas with enlarged and round-up cells that start to detach an.......

Discussion

Virus Generation and Titration

For optimal transfection results, the quality and amount of linearized vector appear most important. We did not observe negative effects on primary lysate production from an initial overgrowth of the culture since the infection will quickly proceed once efficient virus production occurs. However, virus production by HEK293A cells can be affected by long inserts that decrease the efficiency. Some open reading frames were actually found to interfere with virus product.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
pENTR/D-TOPO Cloning Kit	Invitrogen	K240020
Gateway LR Clonase II Enzyme mix	Invitrogen	11791020
PacI	New England Biolabs	R057S
jetPEI	Polyplus-transfection	101-10N
HEK293A Cell Line	Invitrogen	R705-07
A549	ATCC	CCL-185
6-well plates	BD Falcon	353046
14 cm tissue culture dish	Nunc	168381
BALB/cJ-Tg(DO11.10)10Dlo Tg(CARΔ1)1Jdgr	Taconic Farms	Model Nr. 4285
Naive CD4+ T Cell Isolation Kit II	Miltenyi Biotech	130-094-131
DMEM	Invitrogen	41966-052
FBS	PAN Biotech	1502-P110704
PenStrep	Invitrogen	15140-122
RPMI 1640	Lonza	BE12-167F
NaPyruvate	Lonza	BE13-115E
NEAA 100x	Lonza	BE13-114E
L-Glutamine	Invitrogen	25030
HEPES Buffer Solution (1 M)	Invitrogen	15630-056
β-Mercaptoethanol	Sigma-Aldrich	M-7522
MEM Essential vitamin mixture (100x)	Lonza	13-607C
Dynabeads Mouse T-Activator CD3/CD28 for Cell Expansion and Activation	Invitrogen	114-56D
Recombinant Human TGF-beta 1	R&D Systems	240B
Proleukin S (18 x 106IE)	Novartis
LIVE/DEAD Fixable Blue Dead Cell Stain Kit	Invitrogen	L-23105
Mouse BD Fc BlockT	BD Pharmingen	553141
Anti-Mouse/Rat Foxp3 PE	eBioscience	12-5773-82
Mmu-miR-155 TaqMan MicroRNA Assay	Roche Applied Biosystems	4427975
LightCycler 480 Probes Master	Roche Applied Biosystems	04902343001
TaqMan MicroRNA Reverse Transcription Kit	Roche Applied Biosystems	4366596