Modulation of regulatory T cell-Th17 balance by plasmacytoid dendritic cells.

Tregs represent an interesting therapeutic tool to modulate immune responses that could be deleterious in autoimmune diseases and in transplantation. However, phenotype and functions of Tregs do not seem to be stable, and recent data suggest that FoxP3-expressing Tregs can be driven to produce IL-17. In this study, we have analyzed the role of pDCs versus cDCs on Treg responses and underlined that pDCs have an intrinsic, unique capacity to induce IL-17 secretion from T cells.

Mechanism and localization of CD8 regulatory T cells in a heart transplant model of tolerance.

Despite accumulating evidence for the importance of allospecific CD8(+) regulatory T cells (Tregs) in tolerant rodents and free immunosuppression transplant recipients, mechanisms underlying CD8(+) Treg-mediated tolerance remain unclear. By using a model of transplantation tolerance mediated by CD8(+) Tregs following CD40Ig treatment in rats, in this study, we show that the accumulation of tolerogenic CD8(+) Tregs and plasmacytoid dendritic cells (pDCs) in allograft and spleen but not lymph nodes was associated with tolerance induction in vascularized allograft recipients. pDCs preferentially induced tolerogenic CD8(+) Tregs to suppress CD4(+) effector cells responses to first-donor Ags in vitro.

Toward MSC in solid organ transplantation: 2008 position paper of the MISOT study group.

The following position paper summarizes the recommendations for early clinical trials and ongoing basic research in the field of mesenchymal stem cell-induced solid organ graft acceptance--agreed upon on the first meeting of the Mesenchymal Stem Cells In Solid Organ Transplantation (MISOT) study group in late 2008.

Differential control of T regulatory cell proliferation and suppressive activity by mature plasmacytoid versus conventional spleen dendritic cells.

Anergy and suppression are cardinal features of CD4(+)CD25(+)Foxp3(+) T cells (T regulatory cells (Treg)) which have been shown to be tightly controlled by the maturation state of dendritic cells (DC). However, whether lymphoid organ DC subsets exhibit different capacities to control Treg is unclear. In this study, we have analyzed, in the rat, the role of splenic CD4(+) and CD4(-) conventional DC and plasmacytoid DC (pDC) in allogeneic Treg proliferation and suppression in vitro.

A role for heme oxygenase-1 in the immunosuppressive effect of adult rat and human mesenchymal stem cells.

Mesenchymal stem cells (MSCs) display immunomodulatory properties mediated by various factors, including inducible nitric oxide synthase (iNOS). Since heme oxygenase-1 (HO-1) is a potent immunosuppressive enzyme, we tested the hypothesis that HO-1 could mediate the immunosuppressive effects of MSCs. We generated adult rat MSCs that inhibited T-cell proliferation in vitro.