Abstract
BackgroundTherapies directed at augmenting regulatory T cell (Treg) activities in vivo as a systemic treatment for autoimmune disorders and transplantation may be associated with significant off-target effects, including a generalized immunosuppression that may compromise beneficial immune responses to infections and cancer cells. Adoptive cellular therapies using purified expanded Tregs represents an attractive alternative to systemic treatments, with results from animal studies noting increased therapeutic potency of antigen-specific Tregs over polyclonal populations. However, current methodologies are limited in terms of the capacity to isolate and expand a sufficient quantity of endogenous antigen-specific Tregs for therapeutic intervention. Moreover, FOXP3+ Tregs fall largely within the CD4+ T cell subset and are thus routinely MHC class II-specific, whereas class I-specific Tregs may function optimally in vivo by facilitating direct tissue recognition.Methodology/Principal FindingsTo overcome these limitations, we have developed a novel means for generating large numbers of antigen-specific Tregs involving lentiviral T cell receptor (TCR) gene transfer into in vitro expanded polyclonal natural Treg populations. Tregs redirected with a high-avidity class I-specific TCR were capable of recognizing the melanoma antigen tyrosinase in the context of HLA-A*0201 and could be further enriched during the expansion process by antigen-specific reactivation with peptide loaded artificial antigen presenting cells. These in vitro expanded Tregs continued to express FOXP3 and functional TCRs, and maintained the capacity to suppress conventional T cell responses directed against tyrosinase, as well as bystander T cell responses. Using this methodology in a model tumor system, murine Tregs designed to express the tyrosinase TCR effectively blocked antigen-specific effector T cell (Teff) activity as determined by tumor cell growth and luciferase reporter-based imaging.Conclusions/SignificanceThese results support the feasibility of class I-restricted TCR transfer as a promising strategy to redirect the functional properties of Tregs and provide for a more efficacious adoptive cell therapy.
Highlights
Natural regulatory T cells, defined by expression of the transcription factors FOXP3 [1] and more recently Eos [2], play a critical role in maintaining immune tolerance [3]
The multicystronic expression vector allowed for equimolar T cell receptor (TCR) a and b chains by the inclusion of a T2A element [35] followed by an internal ribosome entry site (IRES) element and eGFP reporter (Figure 1A)
Lentiviral infected Tregs expand with similar kinetics to mock-infected Tregs and maintain the phenotypic and functional characteristics of Natural regulatory T cells (nTregs) in vitro
Summary
Natural regulatory T cells (nTregs), defined by expression of the transcription factors FOXP3 [1] and more recently Eos [2], play a critical role in maintaining immune tolerance [3]. Relatively non-specific therapies such as anti-CD3, anti-thymocyte globulin, cytokines, and adhesion molecule based agents are associated with significant non-specific immunological effects and side-effects. Despite these limitations, important mechanistic findings have emerged from these immune therapies. Short term modulation of T cells can elicit longterm effects on immune tolerance [5] Many of these agents thought to provide long-lived efficacy are considered to do so through promoting Treg subsets [6]. Therapies directed at augmenting regulatory T cell (Treg) activities in vivo as a systemic treatment for autoimmune disorders and transplantation may be associated with significant off-target effects, including a generalized immunosuppression that may compromise beneficial immune responses to infections and cancer cells. FOXP3+ Tregs fall largely within the CD4+ T cell subset and are routinely MHC class II-specific, whereas class I-specific Tregs may function optimally in vivo by facilitating direct tissue recognition
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
