A Role for TGF-β in the Generation and Expansion of CD4+CD25+ Regulatory T Cells from Human Peripheral Blood

Abstract

An elusive goal in transplanting organs across histocompatibility barriers has been the induction of specific tolerance to avoid graft rejection. A considerable body of evidence exists that the thymus produces regulatory T cells that suppress the response of other T cells to antigenic stimulation. We report that TGF-β can induce certain CD4+ T cells in the naive (CD45RA+RO−) fraction in human peripheral blood to develop powerful, contact-dependent suppressive activity that is not antagonized by anti-TGF-β or anti-IL-10 mAbs. The costimulatory effects of TGF-β on naive CD4+ T cells up-regulated CD25 and CTLA-4 expression, increased their transition to the activated phenotype, but decreased activation-induced apoptosis. Suppressive activity was concentrated in the CD25+ fraction. These CD4+CD25+ regulatory cells prevented CD8+ T cells from proliferating in response to alloantigens and from becoming cytotoxic effector cells. Moreover, these regulatory cells exerted their suppressive activities in remarkably low numbers and maintained these effects even after they are expanded. Once activated, their suppressive properties were Ag nonspecific. Although <1% of naive CD4+ T cells expressed CD25, depletion of this subset before priming with TGF-β markedly decreased the generation of suppressive activity. This finding suggests that CD4+CD25+ regulatory T cells induced ex vivo are the progeny of thymus-derived regulatory T cells bearing a similar phenotype. The adoptive transfer of these regulatory T cells generated and expanded ex vivo has the potential to prevent rejection of allogeneic organ grafts.

Generation Ex Vivo of TGF-β-Producing Regulatory T Cells from CD4+CD25− Precursors

“…Previously, we have reported that TGF-␤ can induce mitogen-stimulated CD8 ϩ T cells to suppress T cell-dependent Ab production (3,4). We have also observed that TGF-␤ can generate CD4 ϩ CD25 ϩ cells that have very potent contact-dependent suppressive effects on alloactivated on CD8 ϩ T cells (5). These suppressive effects were similar to, if not identical with, the "professional" CD4 ϩ CD25 ϩ T cells described by others (6,7).…”

IL-2 Is Essential for TGF-β to Convert Naive CD4+CD25− Cells to CD25+Foxp3+ Regulatory T Cells and for Expansion of These Cells

“…We reported previously that TCR stimulation of CD4 ϩ cells with TGF-␤ enhances expression of CD25, CD122, CTLA-4, and GITR (8,16,19,20). Fig.…”

MicroRNAs targeting TGFβ signalling underlie the regulatory T cell defect in multiple sclerosis

“…The observed shifts in MFI indicate that there is less TGFbR1 and SMAD4 on a per cell basis when these miRNAs are elevated in naïve CD4 T cells. Given that TGFb signalling is required for the development of Tregs (Yamagiwa et al, 2001;Zheng et al, 2002;Chen et al, 2003), the elevated expression of these miRNAs in patients with multiple sclerosis' naïve CD4 T cells suggests that these miRNAs play a role in the Treg defect observed in patients with multiple sclerosis.…”

“…Pathway analysis predicted that the transforming growth factor-beta (TGFb) signalling pathway was potentially altered by the differential expression of miRNAs in the naïve T cells of patients with multiple sclerosis. TGFb is a cytokine known to be particularly important in the development and function of regulatory T cells (Tregs) (Yamagiwa et al, 2001;Zheng et al, 2002;Chen et al, 2003), protectors against autoimmune responses (Suri-Payer et al, 1998;Itoh et al, 1999;Sakaguchi, 2004). Tregs in patients with multiple sclerosis, while normal in number, demonstrate diminished suppressive effect on myelin-specific autoreactive T cells, low FOXP3 expression, and a less diverse T cell receptor (TCR) repertoire (Viglietta et al, 2004;Haas et al, 2005Haas et al, , 2007Huan et al, 2005;Kumar et al, 2006;Venken et al, 2008).…”