RESUMEN
Hemophilia A (HA) is a blood clotting disorder that is caused by various genetic deficiencies in the factor VIII (FVIII)-encoding F8 gene. Patients receiving FVIII-replacement therapy are at risk for developing neutralizing antibodies (FVIII inhibitors), rendering the FVIII-replacement therapy ineffective. Immunological tolerance toward FVIII can be achieved through immune tolerance induction protocols in some patients, but this is a lengthy and costly desensitization program. Long-term eradication of inhibitors in patients with HA could be achieved by antigen-specific immunotherapy targeting CD4+ T-cells, because formation of FVIII inhibitors is T-cell dependent. Here, we report a peptide-based antigen-specific immunotherapy that is designed to specifically reestablish immune tolerance to FVIII through the development of antigen-processing-independent epitopes (apitopes). We identified 2 FVIII immunodominant peptides in immunized HLA-DRA*0101/DRB1*1501 transgenic (HLA-DR2tg) mice that were optimized for tolerogenicity. These modified peptide analogs were initially screened for recognition using FVIII-specific T-cell hybridoma clones from FVIII-immunized HLA-DR2tg mice. The FVIII apitopes were promiscuous and bound common human HLA-DRB1* allelic variants. The combination of these 2 FVIII apitopes (ATX-F8-117), administered according to a dose-escalation protocol, promoted T-cell tolerance toward FVIII in HLA-DR2tg mice. Furthermore, treatment with ATX-F8-117 significantly reduced FVIII inhibitor formation. ATX-F8-117 regulates anti-FVIII T-cell and B-cell responses, specifically the generation of FVIII inhibitors, revealing peptide-based antigen-specific immunotherapy as a promising approach to suppress and treat inhibitor formation in susceptible patients with HA.
Asunto(s)
Hemofilia A , Animales , Hemofilia A/genética , Humanos , Tolerancia Inmunológica , Factores Inmunológicos , Inmunoterapia , Ratones , Ratones TransgénicosRESUMEN
Current treatments for autoimmune diseases do not address the immune pathology underlying their initiation and progression and too often rely on non-specific immunosuppressive drugs for control of symptoms. Antigen-specific immunotherapy aims to induce tolerance selectively among the cells causing the disease while leaving the rest of the adaptive immune system capable of protecting against infectious diseases and cancers. Here we describe how novel approaches for antigen-specific immunotherapy are designed to manipulate antigen presentation and promote tolerance to specific self-antigens. This analysis points to liver antigen presenting cells, targeted by carrier particles, and steady-state dendritic cells, to which antigen-processing independent T-cell epitopes (apitopes) bind directly, as the principal targets for antigen-specific immunotherapy. Delivery of antigens to these cells holds great promise for effective control of this rapidly expanding group of diseases.
Asunto(s)
Presentación de Antígeno/inmunología , Enfermedades Autoinmunes/inmunología , Animales , Células Presentadoras de Antígenos/inmunología , HumanosRESUMEN
Immunotherapy with antigen-processing independent T cell epitopes (apitopes) targeting autoreactive CD4+ T cells has translated to the clinic and been shown to modulate progression of both Graves' disease and multiple sclerosis. The model apitope (Ac1-9[4Y]) renders antigen-specific T cells anergic while repeated administration induces both Tr1 and Foxp3+ regulatory cells. Here we address why CD4+ T cell epitopes should be designed as apitopes to induce tolerance and define the antigen presenting cells that they target in vivo. Furthermore, we reveal the impact of treatment with apitopes on CD4+ T cell signaling, the generation of IL-10-secreting regulatory cells and the systemic migration of these cells. Taken together these findings reveal how apitopes induce tolerance and thereby mediate antigen-specific immunotherapy of autoimmune diseases.
Asunto(s)
Presentación de Antígeno/inmunología , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/terapia , Autoinmunidad , Epítopos de Linfocito T/inmunología , Inmunoterapia/métodos , Animales , Células Presentadoras de Antígenos/inmunología , Células Presentadoras de Antígenos/metabolismo , Citocinas/metabolismo , Modelos Animales de Enfermedad , Encefalomielitis Autoinmune Experimental , Tolerancia Inmunológica , Activación de Linfocitos , Ratones , Ratones Transgénicos , Péptidos/química , Péptidos/inmunologíaRESUMEN
OBJECTIVE: The study was designed to test the efficacy of ATX-MS-1467 in a relevant preclinical model and to assess its safety for the treatment of patients with secondary progressive multiple sclerosis (SPMS). METHODS: ATX-MS-1467 was tested for its ability to suppress experimental autoimmune encephalomyelitis (EAE) in the (Ob x DR2)F1 mouse both before and after disease onset. Safety was assessed by clinical assessment, MRI analysis, and the measurement of immune responses to self- and nonself-antigens in patients with SPMS. RESULTS: ATX-MS-1467 displayed a dose-dependent inhibition of EAE and was more effective than glatiramer acetate in the treatment of ongoing disease in humanized mice. A phase 1 open-label dose-escalating study demonstrated that ATX-MS-1467 was safe and well-tolerated in a group of 6 patients with SPMS, up to a dose of 800 µg. CONCLUSIONS: The results of this study support further development of ATX-MS-1467 in a clinical trial powered to investigate the immunologic and clinical benefits of treatment in relapsing-remitting MS. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that ATX-MS-1467 is safe and tolerated in a group of 6 patients with SPMS.
RESUMEN
Regulation of the immune response to self- and foreign antigens is vitally important for limiting immune pathology associated with both infections and hypersensitivity conditions. Control of autoimmune conditions can be reinforced by tolerance induction with peptide epitopes, but the mechanism is not currently understood. Repetitive intranasal administration of soluble peptide induces peripheral tolerance in myelin basic protein (MBP)-specific TCR transgenic mice. This is characterized by the presence of anergic, interleukin (IL)-10-secreting CD4(+) T cells with regulatory function (IL-10 T reg cells). The differentiation pathway of peptide-induced IL-10 T reg cells was investigated. CD4(+) T cells became anergic after their second encounter with a high-affinity MBP peptide analogue. Loss of proliferative capacity correlated with a switch from the Th1-associated cytokines IL-2 and interferon (IFN)-gamma to the regulatory cytokine IL-10. Nevertheless, IL-10 T reg cells retained the capacity to produce IFN-gamma and concomitantly expressed T-bet, demonstrating their Th1 origin. IL-10 T reg cells suppressed dendritic cell maturation, prevented Th1 cell differentiation, and thereby created a negative feedback loop for Th1-driven immune pathology. These findings demonstrate that Th1 responses can be self-limiting in the context of peripheral tolerance to a self-antigen.
Asunto(s)
Autoinmunidad , Interleucina-10/biosíntesis , Células TH1/citología , Células TH1/inmunología , Animales , Antígenos/administración & dosificación , Autoantígenos/administración & dosificación , Diferenciación Celular , Anergia Clonal , Citocinas/sangre , Células Dendríticas/inmunología , Retroalimentación Fisiológica , Expresión Génica , Interferón gamma/biosíntesis , Ratones , Ratones Transgénicos , Proteína Básica de Mielina , Proteínas del Tejido Nervioso/inmunología , Fragmentos de Péptidos/inmunología , Autotolerancia , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/inmunología , Factores de Transcripción/inmunologíaRESUMEN
Recent studies have emphasized the importance of T cells with regulatory/suppressor properties in controlling autoimmune diseases. A number of different types of regulatory T cells have been described with the best characterized being the CD25(+) population. In addition, it has been shown that regulatory T cells can be induced by specific Ag administration. In this study, we investigate the relationship between peptide-induced, CD4(+) regulatory T cells and naturally occurring CD4(+)CD25(+) cells derived from the Tg4 TCR-transgenic mouse. Peptide-induced cells were FoxP3(-) and responded to Ag by secreting IL-10, whereas CD25(+) cells failed to secrete this cytokine. Both cell types were able to suppress the proliferation of naive lymphocytes in vitro although with distinct activation sensitivities. Depletion of CD25(+) cells did not affect the suppressive properties of peptide-induced regulators. Furthermore, peptide-induced regulatory/suppressor T cells could be generated in RAG(-/-), TCR-transgenic mice that do not spontaneously generate CD25(+) regulatory cells. These results demonstrate that these natural and induced regulatory cells fall into distinct subsets.