RESUMO
Dendritic cell (DC) modification is a potential strategy to induce clinical transplantation tolerance. We compared two DC modification strategies to inhibit allogeneic T-cell proliferation. In the first strategy, murine DCs were transduced with a lentiviral vector expressing CTLA4-KDEL, a fusion protein that prevents surface CD80/86 expression by retaining the co-stimulatory molecules within the ER. In the second approach, DCs were transduced to express the tryptophan-catabolising enzyme IDO. CTLA4-KDEL-expressing DCs induced anergy in alloreactive T cells and generated both CD4(+) CD25(+) and CD4(+) CD25(-) Treg cells (with direct and indirect donor allospecificity and capacity for linked suppression) both in vitro and in vivo. In contrast, T-cell unresponsiveness induced by IDO(+) DCs lacked donor specificity. In the absence of any immunosuppressive treatment, i.v. administration of CTLA4-KDEL-expressing DCs resulted in long-term survival of corneal allografts only when the DCs were capable of indirect presentation of alloantigen. This study demonstrates the therapeutic potential of CTLA4-KDEL-expressing DCs in tolerance induction.
Assuntos
Transplante de Córnea , Células Dendríticas/imunologia , Rejeição de Enxerto/imunologia , Imunomodulação , Tolerância ao Transplante/imunologia , Transferência Adotiva , Animais , Antígeno CTLA-4/genética , Antígeno CTLA-4/imunologia , Sobrevivência Celular/genética , Sobrevivência Celular/imunologia , Anergia Clonal/imunologia , Células Dendríticas/metabolismo , Feminino , Expressão Gênica , Vetores Genéticos/genética , Rejeição de Enxerto/prevenção & controle , Sobrevivência de Enxerto/genética , Sobrevivência de Enxerto/imunologia , Imunomodulação/genética , Lentivirus/genética , Ativação Linfocitária/imunologia , Camundongos , Oligopeptídeos/imunologia , Fenótipo , Sinais Direcionadores de Proteínas , Linfócitos T/imunologia , Linfócitos T Reguladores/imunologia , Transdução Genética , Transplante HomólogoRESUMO
Activation of T lymphocytes requires the recognition of peptide-major histocompatibility complexes (MHCs) and costimulatory signals provided by antigen-presenting cells (APCs). It has been shown that T-cell activation without costimulation can lead to anergy. In this study, we developed a novel strategy to inhibit expression of B7 molecules (CD80/86) by transfecting APCs with a gene construct encoding a modified cytotoxic T lymphocyte antigen 4 (CTLA4) molecule (CTLA4-KDEL) that is targeted to the endoplasmic reticulum (ER). APCs expressing this construct failed to express CD80/86 on their surface, were unable to stimulate allogeneic and peptide-specific T-cell responses, and induced antigen-specific anergy of the responding T cells. Cells expressing CTLA4-KDEL do not up-regulate the indoleamine 2, 3-dioxygenase enzyme, unlike cells treated with soluble CTLA4-immunoglobin (Ig). This gene-based strategy to knock out surface receptors is an attractive alternative to using immature dendritic cells for preventing transplant rejection and treating of autoimmune diseases.