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Secretion of interleukin-10 (IL-10) by CD4+ T cells is an essential immunoregulatory mechanism. The work presented here assesses the role of the signaling molecule protein kinase C theta (PKCθ) in the induction of IL-10 expression in CD4+ T cells. Using wildtype and PKCθ-deficient Tg4 T cell receptor transgenic mice, we implemented a well-described protocol of repeated doses of myelin basic protein (MBP)Ac1-9[4Y] antigen to induce Tr1-like IL-10+ T cells. We find that PKCθ is required for the efficient induction of IL-10 following antigen administration. Both serum concentrations of IL-10 and the proportion of IL-10+ T cells were reduced in PKCθ-deficient mice relative to wildtype mice following [4Y] treatment. We further characterized the T cells of [4Y] treated PKCθ-deficient Tg4 mice and found reduced expression of the transcription factors cMaf, Nfil3 and FoxP3 and the surface receptors PD-1 and Tim3, all of which have been associated with the differentiation or function of IL-10+ T cells. Finally, we demonstrated that, unlike [4Y] treated wildtype Tg4 T cells, cells from PKCθ-deficient mice were unable to suppress the priming of naïve T cells in vitro and in vivo. In summary, we present data demonstrating a role for PKCθ in the induction of suppressive, IL-10-secreting T cells induced in TCR-transgenic mice following chronic antigen administration. This should be considered when contemplating PKCθ as a suitable drug target for inducing immune suppression and graft tolerance. [ABSTRACT FROM AUTHOR]

In vitro induced Foxp3+ T regulatory (iTreg) cells form a novel and promising target for therapeutic tolerance induction. However, the potential of these cells as a target for the treatment of various immune diseases, as well as the factors involved in their development and function, remain debated. Here, we demonstrate in a myelin basic protein (MBP)-specific murine model of CNS autoimmune disease that adoptive transfer of antigen-specific iTreg cells ameliorates disease progression. Moreover, we show that the co-stimulatory molecule CTLA-4 mediates in vitro differentiation of iTreg cells. Finally, we demonstrate that the secreted, immunosuppressive cytokine IL-10 controls the ability of antigen-specific iTreg cells to suppress autoimmune disease. Overall, we conclude that antigen-specific iTreg cells, which depend on various immune regulatory molecules for their differentiation and function, represent a major target for effective immunotherapy of autoimmune disease. [ABSTRACT FROM AUTHOR]

T regulatory (Treg) cells expressing the transcription factor FoxP3 play a key role in protection against autoimmune disease. GFP-FoxP3 reporter mice have been used widely to study the induction, function and stability of both thymically- and peripherally-induced Treg cells. The N-terminal modification of FoxP3, however, affects its interaction with transcriptional co-factors; this can alter Treg cell development and function in certain self-antigen specific animal models. Interestingly, Treg cell function can be negatively or positively affected, depending on the nature of the model. In this study, we focused on the effect of the GFP-FoxP3 reporter on Treg cell development and function in the Tg4 mouse model. In this model, T cells express a transgenic T cell receptor (TCR) specific for the Myelin Basic Protein (MBP) peptide Ac1-9, making the animals susceptible to experimental autoimmune encephalomyelitis (EAE), a disease akin to multiple sclerosis in humans. Unlike diabetes-susceptible mice, Tg4 FoxP3gfp mice did not develop spontaneous autoimmune disease and did not demonstrate augmented susceptibility to induced disease. Concurrently, thymic generation of natural Treg cells was not negatively affected. The induction of FoxP3 expression in naive peripheral T cells was, however, significantly impaired as a result of the transgene. This study shows that the requirements for the interaction of FoxP3 with co-factors, which governs its regulatory ability, differ not only between natural and inducible Treg cells but also between animal models of diseases such as diabetes and EAE. [ABSTRACT FROM AUTHOR]