RESUMO
The identification of factors that promote ß cell proliferation could ultimately move type 1 diabetes treatment away from insulin injection therapy and toward a cure. We have performed high-throughput, cell-based screens using rodent ß cell lines to identify molecules that induce proliferation of ß cells. Herein we report the discovery and characterization of WS6, a novel small molecule that promotes ß cell proliferation in rodent and human primary islets. In the RIP-DTA mouse model of ß cell ablation, WS6 normalized blood glucose and induced concomitant increases in ß cell proliferation and ß cell number. Affinity pulldown and kinase profiling studies implicate Erb3 binding protein-1 and the IκB kinase pathway in the mechanism of action of WS6.
Assuntos
Ensaios de Triagem em Larga Escala , Ilhotas Pancreáticas/efeitos dos fármacos , Ureia/farmacologia , Animais , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Humanos , Ilhotas Pancreáticas/citologia , Camundongos , Estrutura Molecular , Peso Molecular , Relação Estrutura-Atividade , Ureia/análogos & derivados , Ureia/químicaRESUMO
A defining characteristic of persistent viral infections is the loss and functional inactivation of antiviral effector T cells, which prevents viral clearance. Interleukin-10 (IL-10) suppresses cellular immune responses by modulating the function of T cells and antigen-presenting cells. In this paper, we report that IL-10 production is drastically increased in mice persistently infected with lymphocytic choriomeningitis virus. In vivo blockade of the IL-10 receptor (IL-10R) with a neutralizing antibody resulted in rapid resolution of the persistent infection. IL-10 secretion was diminished and interferon gamma production by antiviral CD8+ T cells was enhanced. In persistently infected mice, CD8alpha+ dendritic cell (DC) numbers declined early after infection, whereas CD8alpha- DC numbers were not affected. CD8alpha- DCs supported IL-10 production and subsequent dampening of antiviral T cell responses. Therapeutic IL-10R blockade broke the cycle of IL-10-mediated immune suppression, preventing IL-10 priming by CD8alpha- DCs and enhancing antiviral responses and thereby resolving infection without causing immunopathology.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/terapia , Vírus da Coriomeningite Linfocítica , Receptores de Interleucina-10/antagonistas & inibidores , Receptores de Interleucina-10/imunologia , Animais , Anticorpos Monoclonais/administração & dosagem , Doença Crônica , Soros Imunes/administração & dosagem , Interleucina-10/antagonistas & inibidores , Interleucina-10/deficiência , Interleucina-10/genética , Interleucina-10/metabolismo , Coriomeningite Linfocítica/metabolismo , Vírus da Coriomeningite Linfocítica/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ratos , Receptores de Interleucina-10/biossínteseRESUMO
Signaling through TLR2 promotes inflammation and modulates CD4(+) CD25(+) Tregs. We assessed mechanistically how this molecule would alter immunoregulation in type 1 diabetes (T1D). We also asked whether TLR2 may be involved in our recent discovery that viral infection can protect from autoimmune diabetes by expanding and invigorating Tregs. Treatment of prediabetic mice with a synthetic TLR2 agonist diminished T1D and increased the number and function of CD4(+) CD25(+) Tregs, also conferring DCs with tolerogenic properties. TLR2 ligation also promoted the expansion of Tregs upon culture with DCs and ameliorated their capacity to prevent the disease. Protection from T1D by lymphocytic choriomeningitis virus (LCMV) infection depended on TLR2. LCMV increased the frequency of CD4(+) CD25(+) Tregs and their production of TGF-ß more significantly in WT than TLR2-deficient mice. Furthermore, LCMV infection in vivo or LCMV-infected DCs in vitro rendered, via TLR2, CD4(+) CD25(+) Tregs capable of diminishing T1D. We identify novel mechanisms by which TLR2 promotes immunoregulation and controls autoimmune diabetes in naïve or infected hosts. This work should help understand T1D etiology and develop novel immune-based therapeutic interventions.
Assuntos
Infecções por Arenaviridae/imunologia , Diabetes Mellitus Tipo 1/imunologia , Linfócitos T Reguladores/imunologia , Receptor 2 Toll-Like/metabolismo , Animais , Antígenos CD4/imunologia , Células Cultivadas , Células Dendríticas/imunologia , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/prevenção & controle , Citometria de Fluxo , Imunidade Inata , Inflamação/imunologia , Subunidade alfa de Receptor de Interleucina-2/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Knockout , Estado Pré-Diabético/imunologia , Transdução de Sinais , Receptor 2 Toll-Like/agonistas , Receptor 2 Toll-Like/genética , Receptor 2 Toll-Like/imunologia , Fator de Crescimento Transformador beta/biossínteseRESUMO
One of the requirements for efficient vaccination against infection is to achieve the best combination of an adequate adjuvant with the antigenic information to deliver. Although plasmid DNA is a promising tool bearing the unique potential to activate humoral and cellular immunity, an actual challenge is to increase plasmid immunogenicity in human vaccination protocols in which efficacy has proven rather limited. Previous work showed that the bacterial DNA backbone of the plasmid has potent adjuvant properties because it contains CpG motifs that are particular activating nucleotidic sequences. Among TLRs, which are key sensors of microbial products, TLR9 can detect CpG motifs and confer activation of APCs, such as dendritic cells. However, whether the immunogenic properties of plasmid DNA involve TLR9 signaling has not been clearly established. In the current study, we demonstrate that TLR9 determines the effectiveness of vaccination against lethal lymphocytic choriomeningitis virus infection using plasmid DNA in a prime, but not prime-boost, vaccination regimen. Furthermore, we provide evidence that the presence of TLR9 in dendritic cells is necessary for effective and functional priming of virus-specific CD8+ T cells upon plasmid exposure in vitro or single-dose vaccination in vivo. Therefore, at single or low vaccine doses that are often used in human-vaccination protocols, CpG/TLR9 interactions participate in the immunogenicity of plasmid DNA. These results suggest that the TLR9 signaling pathway is involved in the efficacy of plasmid vaccination; therefore, it should remain a focus in the development or amelioration of vaccines to treat infections in humans.
Assuntos
Células Dendríticas/imunologia , Plasmídeos/imunologia , Receptor Toll-Like 9/imunologia , Vacinação/métodos , Vacinas de DNA/imunologia , Vacinas Virais/imunologia , Animais , Linfócitos T CD8-Positivos/imunologia , Separação Celular , Citometria de Fluxo , Imunização Secundária , Ativação Linfocitária/imunologia , Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/prevenção & controle , Vírus da Coriomeningite Linfocítica , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Oligodesoxirribonucleotídeos/imunologia , Transdução de Sinais/imunologiaRESUMO
Insufficient pancreatic ß-cell mass or function results in diabetes mellitus. While significant progress has been made in regulating insulin secretion from ß-cells in diabetic patients, no pharmacological agents have been described that increase ß-cell replication in humans. Here we report aminopyrazine compounds that stimulate robust ß-cell proliferation in adult primary islets, most likely as a result of combined inhibition of DYRK1A and GSK3B. Aminopyrazine-treated human islets retain functionality in vitro and after transplantation into diabetic mice. Oral dosing of these compounds in diabetic mice induces ß-cell proliferation, increases ß-cell mass and insulin content, and improves glycaemic control. Biochemical, genetic and cell biology data point to Dyrk1a as the key molecular target. This study supports the feasibility of treating diabetes with an oral therapy to restore ß-cell mass, and highlights a tractable pathway for future drug discovery efforts.
Assuntos
Proliferação de Células , Quinase 3 da Glicogênio Sintase/genética , Células Secretoras de Insulina/citologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genética , Animais , Divisão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/fisiopatologia , Regulação para Baixo/efeitos dos fármacos , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/enzimologia , Masculino , Camundongos , Camundongos Transgênicos , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Piridazinas/farmacologia , Quinases DyrkRESUMO
Adjuvants increase vaccine potency largely by activating innate immunity and promoting inflammation. Limiting the side effects of this inflammation is a major hurdle for adjuvant use in vaccines for humans. It has been difficult to improve on adjuvant safety because of a poor understanding of adjuvant mechanism and the empirical nature of adjuvant discovery and development historically. We describe new principles for the rational optimization of small-molecule immune potentiators (SMIPs) targeting Toll-like receptor 7 as adjuvants with a predicted increase in their therapeutic indices. Unlike traditional drugs, SMIP-based adjuvants need to have limited bioavailability and remain localized for optimal efficacy. These features also lead to temporally and spatially restricted inflammation that should decrease side effects. Through medicinal and formulation chemistry and extensive immunopharmacology, we show that in vivo potency can be increased with little to no systemic exposure, localized innate immune activation and short in vivo residence times of SMIP-based adjuvants. This work provides a systematic and generalizable approach to engineering small molecules for use as vaccine adjuvants.
Assuntos
Adjuvantes Imunológicos/farmacologia , Desenho de Fármacos , Vacinas/administração & dosagem , Adjuvantes Imunológicos/administração & dosagem , Adjuvantes Imunológicos/farmacocinética , Disponibilidade BiológicaRESUMO
Type 1 diabetes (T1D) is an autoimmune disease that is caused by the destruction of insulin-producing beta cells. Viral infections induce immune responses that can damage beta cells and promote T1D or on the other hand prevent the development of the disease. However, the opposing roles of viral infections in T1D are not understood mechanistically. We report here that viruses that do not inflict damage on beta cells provided protection from T1D by triggering immunoregulatory mechanisms. Infection of prediabetic NOD mice with Coxsackie virus B3 or lymphocytic choriomeningitis virus (LCMV) delayed diabetes onset and reduced disease incidence. Delayed T1D onset was due to transient upregulation of programmed cell death-1 ligand 1 (PD-L1) on lymphoid cells, which prevented the expansion of diabetogenic CD8+ T cells expressing programmed cell death-1 (PD-1). Reduced T1D incidence was caused by increased numbers of invigorated CD4+CD25+ Tregs, which produced TGF-beta and maintained long-term tolerance. Full protection from T1D resulted from synergy between PD-L1 and CD4+CD25+ Tregs. Our results provide what we believe to be novel mechanistic insight into the role of viruses in T1D and should be valuable for prospective studies in humans.
Assuntos
Infecções por Coxsackievirus/imunologia , Infecções por Coxsackievirus/prevenção & controle , Infecções por Citomegalovirus/complicações , Infecções por Citomegalovirus/imunologia , Diabetes Mellitus Tipo 1/imunologia , Diabetes Mellitus Tipo 1/prevenção & controle , Doença Aguda , Animais , Antígeno B7-1/imunologia , Antígeno B7-1/metabolismo , Antígeno B7-H1 , Linfócitos T CD8-Positivos/imunologia , Infecções por Coxsackievirus/genética , Infecções por Coxsackievirus/metabolismo , Infecções por Citomegalovirus/metabolismo , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/metabolismo , Feminino , Interferon-alfa/uso terapêutico , Subunidade alfa de Receptor de Interleucina-2/imunologia , Glicoproteínas de Membrana/imunologia , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos NOD , Peptídeos/imunologia , Peptídeos/metabolismo , Linfócitos T Reguladores/imunologia , Fator de Crescimento Transformador beta/biossíntese , Fator de Crescimento Transformador beta/imunologia , Regulação para CimaRESUMO
OBJECTIVE: Transforming growth factor-beta (TGF-beta) can exhibit strong immune suppression but has also been shown to promote T-cell growth. We investigated the differential effect of this cytokine on CD8(+) T-cells in autoimmunity and antiviral immunity. RESEARCH DESIGN AND METHODS: We used mouse models for virally induced type 1 diabetes in conjunction with transgenic systems enabling manipulation of TGF-beta expression or signaling in vivo. RESULTS: Surprisingly, when expressed selectively in the pancreas, TGF-beta reduced apoptosis of differentiated autoreactive CD8(+) T-cells, favoring their expansion and infiltration of the islets. These results pointed to drastically opposite roles of TGF-beta on naïve compared with antigen-experienced/memory CD8(+) T-cells. Indeed, in the absence of functional TGF-beta signaling in T-cells, fast-onset type 1 diabetes caused by activation of naïve CD8(+) T-cells occurred faster, whereas slow-onset disease depending on accumulation and activation of antigen-experienced/memory CD8(+) T-cells was decreased. TGF-beta receptor-deficient CD8(+) T-cells showed enhanced activation and expansion after lymphocytic choriomeningitis virus infection in vivo but were more prone to apoptosis once antigen experienced and failed to survive as functional memory cells. In vitro, TGF-beta suppressed naïve CD8(+) T-cell activation and gamma-interferon production, whereas memory CD8(+) T-cells stimulated in the presence of TGF-beta showed enhanced survival and increased production of interleukin-17 in conjunction with gamma-interferon. CONCLUSIONS: The effect of TGF-beta on CD8(+) T-cells is dependent on their differentiation status and activation history. These results highlight a novel aspect of the pleiotropic nature of TGF-beta and have implications for the design of immune therapies involving this cytokine.
Assuntos
Apoptose/efeitos dos fármacos , Linfócitos T CD8-Positivos/efeitos dos fármacos , Fator de Crescimento Transformador beta/farmacologia , Animais , Apoptose/imunologia , Autoimunidade/imunologia , Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/imunologia , Células Cultivadas , Citometria de Fluxo , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Transgênicos , Pâncreas/efeitos dos fármacos , Pâncreas/imunologia , Pâncreas/metabolismoRESUMO
Type 1 diabetes results from autoimmune destruction of insulin-producing ß cells in the pancreatic islets, leading to deficiency in glucose uptake by the cells of the body. The resulting complications and mortality call into attention the need for therapeutic strategies to treat this disease. While general immunosuppressive treatment and antigen-based therapy have both proven effective in aborting the autoimmune attack on ß cells, cellular therapy and synergistic combination of agents probably represent the most promising approaches for efficient targeting of autoreactive cells. The underlying challenge is fine tuning of immune therapy to avoid harmful side effects on the immune system or other host-defense functions. This should be rendered possible by identifying the optimal regimen and underlying mechanisms of action.
RESUMO
Under what context do dying beta-cells enhance the autoimmune process in type 1 diabetes? Kim et al. (2007) find that secondary necrosis of beta-cells can prime the autoimmune response via uptake by and activation of antigen-presenting cells through Toll-like receptor 2.