Foxp3‐independent loss of regulatory CD4⁺T‐cell suppressive capacities induced by self‐deprivation

Abstract

In the periphery, Foxp3 expression is considered sufficient to maintain natural regulatory CD4 + T-cell suppressive function. In this study, we challenge this model. Indeed, in mouse chimeras in which major histocompatibility complex (MHC) class II expression is restricted to the thymus, peripheral regulatory CD4 + T cells lack suppressive activity. In addition, regulatory CD4 + T cells recovered 5 days after transfer into recipient mice lacking expression of MHC class II molecules (self-deprived) are unable to inhibit the proliferative response of conventional CD4 + T cells both in vitro and in vivo. Disruption of TCR/MHC class II interactions rapidly leads to alterations in the regulatory CD4 + T-cell phenotype, the ability to respond to stimulation and to produce interleukin-10, and the transcriptional signature. Interestingly, self-deprivation does not affect Foxp3 expression indicating that in regulatory CD4 + T cells, self-recognition induces unique transcriptional and functional features that do not rely on Foxp3 expression. Keywords: Autoreactivity r Foxp3 r Regulatory T cells Supporting Information available online IntroductionNaturally occurring regulatory CD4 + T (Treg) cells are important for the maintenance of self-tolerance in the periphery. In particular, they are key players in the prevention of various autoimmune and inflammatory disorders. Natural Treg cells arise in the thymus where T-cell receptor (TCR) signals lead to interleukin (IL)-2 sensitivity enhancement in developing thymocytes. Then, IL-2 signaling induces Foxp3 expression that, in turn, strengthens Treg-cell lineage stability [1,2]. Foxp3 expression is Correspondence: Dr. Bruno Lucas e-mail: bruno.lucas@inserm.fr then important to maintain a distinct transcriptional program required for their suppressive function [3][4][5].Recent studies have clearly established that the TCR has an instructive role in inducing commitment of developing thymocytes into the Treg-cell lineage [6,7]. More precisely, Treg-cell development would be instructed by TCRs with high avidity for self-peptides bound to major histocompatibility complex (MHC) class II molecules (self). Indeed, the proportion of Treg cells is increased when TCR transgenic T cells are forced to see their cognate antigens in the thymus [1,2,8,9]. This model is further supported by the observation that there is a limited amount of * These authors contributed equally to this work. overlap (10-20%) between the TCR sequences expressed within the conventional CD4 + T (Tconv) cell and the Treg-cell repertoire [10]. Interestingly, overlapping is more important when the Tregcell repertoire was compared with the repertoire of pathogenic autoreactive effector T cells [11]. After migrating to the periphery, Treg cells still interact with self. Indeed, based on autoimmune ovarian disease and prostatitis models, Tung and colleagues [12,13] have determined that continuous interactions with self are required to allow Treg cells to accumulate in the draining lymph-nodes. More recently, Lathrop et al. ...

Highly self-reactive naive CD4 T cells are prone to differentiate into regulatory T cells

“…Purified Ly-6C À or Ly-6C þ CD4 T N cells were stimulated for 3 days with coated anti-CD3 and anti-CD28 Abs in the presence of 1 ng ml À 1 of TGFb1 and then let to rest for 3 more days in the presence of recombinant human IL-2 (13 ng ml À 1 ; R&D). GFP-expressing cells were then sorted using flow cytometry, and the suppressive capacities of these highly purified Foxp3-expressing cells were then assessed as previously described 31 . Briefly, conventional CD4 T cells (GFP À CD4 þ T cells) were purified from LNs of C57BL/6 Foxp3-GFP mice, labelled with Cell Trace Violet (Invitrogen) and stimulated for 64 h, alone or together with Treg cells at various Treg/Tconv-cell ratios.…”

IL-2 and IL-7 Determine the Homeostatic Balance between the Regulatory and Conventional CD4+ T Cell Compartments during Peripheral T Cell Reconstitution

“…C57BL/6 CD3ε 2/2 mice (26) were crossed with MHC II D/D mice (27) to obtain CD3ε/MHC II double-deficient mice (CD3ε 2/2 II D/D mice) (13). C57BL/6 Foxp3-GFP reporter mice were initially provided by Dr. Bernard Malissen (Centre d'Immunologie de Marseille-Luminy, Marseille, France) (28,29) and maintained in our own animal facilities. Experiments were carried out in accordance with the guidelines of the French Veterinary Department.…”

Adaptive Immune-like γ/δ T Lymphocytes Share Many Common Features with Their α/β T Cell Counterparts

“…By comparing the other subsets to naive and memory CD8 + a/b T cells, we found that the CD27 + g/d T cell compartment include naive-like and memorylike lymphocytes that share many phenotypic, functional, and homeostatic characteristics with their adaptive a/b T cell counterparts. (18) were maintained in our own animal facilities, under specific pathogen-free conditions. C57BL/6 Foxp3-GFP CD45.2 mice were initially obtained from Dr. Bernard Malissen (Centre d'Immunologie de Marseille-Luminy, France) (19).…”

“…GFPexpressing cells were then flow cytometry sorted, and the suppressive capacities of these highly purified Foxp3-expressing cells were then assessed as previously described (18). Briefly, conventional CD4 T cells (GFP 2 CD4 + T cells) were purified from LNs of C57BL/6 CD45.2 Foxp3-GFP mice, labeled with Cell Trace Violet (Invitrogen), and stimulated for 64 h, alone or together with Tregs at various Treg/conventional T cell ratios.…”