RESUMO
Notch1 signaling is involved in regulatory T (Treg)-cell differentiation. We previously demonstrated that, when cocultured with CD3(+) cells, mesenchymal stem cells (MSCs) induced a T-cell population with a regulatory phenotype. Here, we investigated the molecular mechanism underlying MSC induction of human Treg cells. We show that the Notch1 pathway is activated in CD4(+) T cells cocultured with MSCs. Inhibition of Notch1 signaling through GSI-I or the Notch1 neutralizing antibody reduced expression of HES1 (the Notch1 downstream target) and the percentage of MSC-induced CD4(+) CD25(high) FOXP3(+) cells in vitro. Moreover, we demonstrate that FOXP3 is a downstream target of Notch signaling in human cells. No crosstalk between Notch1 and TGF-ß signaling pathways was observed in our experimental system. Together, these findings indicate that activation of the Notch1 pathway is a novel mechanism in the human Treg-cell induction mediated by MSCs.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Células-Tronco Mesenquimais/imunologia , Receptor Notch1/metabolismo , Subpopulações de Linfócitos T/imunologia , Linfócitos T Reguladores/imunologia , Anticorpos Bloqueadores/farmacologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Antígenos CD4/metabolismo , Diferenciação Celular , Células Cultivadas , Técnicas de Cocultura , Fatores de Transcrição Forkhead/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/imunologia , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Subunidade alfa de Receptor de Interleucina-2/metabolismo , Contagem de Linfócitos , Células-Tronco Mesenquimais/efeitos dos fármacos , Oligopeptídeos/farmacologia , Receptor Notch1/antagonistas & inibidores , Receptor Notch1/imunologia , Transdução de Sinais/efeitos dos fármacos , Subpopulações de Linfócitos T/efeitos dos fármacos , Linfócitos T Reguladores/efeitos dos fármacos , Fatores de Transcrição HES-1RESUMO
Hastening posttransplantation immune reconstitution is a key challenge in human leukocyte antigen (HLA)-haploidentical hematopoietic stem-cell transplantation (HSCT). In experimental models of mismatched HSCT, T-regulatory cells (Tregs) when co-infused with conventional T cells (Tcons) favored posttransplantation immune reconstitution and prevented lethal graft-versus-host disease (GVHD). In the present study, we evaluated the impact of early infusion of Tregs, followed by Tcons, on GVHD prevention and immunologic reconstitution in 28 patients with high-risk hematologic malignancies who underwent HLA-haploidentical HSCT. We show for the first time in humans that adoptive transfer of Tregs prevented GVHD in the absence of any posttransplantation immunosuppression, promoted lymphoid reconstitution, improved immunity to opportunistic pathogens, and did not weaken the graft-versus-leukemia effect. This study provides evidence that Tregs are a conserved mechanism in humans.