RESUMO
Very recently one of the largest type 1 diabetes prevention trials using daily administration of oral insulin or placebo was completed. After 9 years of study enrollment and follow-up, the randomized controlled trial failed to delay the onset of clinical type 1 diabetes, which was the primary end point. The unfortunate outcome follows the previous large-scale trial, the Diabetes Prevention Trial-Type 1 (DPT-1), which again failed to delay diabetes onset with oral insulin or low-dose subcutaneous insulin injections in a randomized controlled trial with relatives at risk for type 1 diabetes. These sobering results raise the important question, "Where does the type 1 diabetes prevention field move next?" In this Perspective, we advocate for a paradigm shift in which smaller mechanistic trials are conducted to define immune mechanisms and potentially identify treatment responders. The stage is set for these interventions in individuals at risk for type 1 diabetes as Type 1 Diabetes TrialNet has identified thousands of relatives with islet autoantibodies and general population screening for type 1 diabetes risk is under way. Mechanistic trials will allow for better trial design and patient selection based upon molecular markers prior to large randomized controlled trials, moving toward a personalized medicine approach for the prevention of type 1 diabetes.
Assuntos
Diabetes Mellitus Tipo 1/tratamento farmacológico , Hipoglicemiantes/administração & dosagem , Insulina/administração & dosagem , Medicina Preventiva , Administração Oral , Ensaios Clínicos como Assunto/história , Ensaios Clínicos como Assunto/métodos , Diabetes Mellitus Tipo 1/sangue , História do Século XX , História do Século XXI , Humanos , Hipoglicemiantes/efeitos adversos , Insulina/efeitos adversos , Medicina Preventiva/história , Medicina Preventiva/métodos , Medicina Preventiva/tendências , Falha de TratamentoRESUMO
Although B cells reactive with islet autoantigens are silenced by tolerance mechanisms in healthy individuals, they can become activated and contribute to the development of type 1 diabetes. We previously demonstrated that high-affinity insulin-binding B cells (IBCs) occur exclusively in the anergic (BND) compartment in peripheral blood of healthy subjects. Consistent with their activation early in disease development, high-affinity IBCs are absent from the BND compartment of some first-degree relatives (FDRs) as well as all patients with autoantibody-positive prediabetes and new-onset type 1 diabetes, a time when they are found in pancreatic islets. Loss of BND IBCs is associated with a loss of the entire BND B-cell compartment consistent with provocation by an environmental trigger or predisposing genetic factors. To investigate potential mechanisms operative in subversion of B-cell tolerance, we explored associations between HLA and non-HLA type 1 diabetes-associated risk allele genotypes and loss of BNDs in FDRs. We found that high-risk HLA alleles and a subset of non-HLA risk alleles (i.e., PTPN2 [rs1893217], INS [rs689], and IKZF3 [rs2872507]), relevant to B- and T-cell development and function are associated with loss of anergy. Hence, the results suggest a role for risk-conferring alleles in perturbation of B-cell anergy during development of type 1 diabetes.
Assuntos
Autoanticorpos/imunologia , Linfócitos B/imunologia , Anergia Clonal/imunologia , Diabetes Mellitus Tipo 1/imunologia , Estado Pré-Diabético/imunologia , Diabetes Mellitus Tipo 1/genética , Predisposição Genética para Doença , Antígenos HLA-DQ/genética , Antígenos HLA-DR/genética , Humanos , Fator de Transcrição Ikaros/genética , Insulina/genética , Ilhotas Pancreáticas , Estado Pré-Diabético/genética , Proteína Tirosina Fosfatase não Receptora Tipo 2/genéticaRESUMO
Type 1 diabetes results from chronic autoimmune destruction of insulin-producing ß-cells within pancreatic islets. Although insulin is a critical self-antigen in animal models of autoimmune diabetes, due to extremely limited access to pancreas samples, little is known about human antigenic targets for islet-infiltrating T cells. Here we show that proinsulin peptides are targeted by islet-infiltrating T cells from patients with type 1 diabetes. We identified hundreds of T cells from inflamed pancreatic islets of three young organ donors with type 1 diabetes with a short disease duration with high-risk HLA genes using a direct T-cell receptor (TCR) sequencing approach without long-term cell culture. Among 85 selected CD4 TCRs tested for reactivity to preproinsulin peptides presented by diabetes-susceptible HLA-DQ and HLA-DR molecules, one T cell recognized C-peptide amino acids 19-35, and two clones from separate donors responded to insulin B-chain amino acids 9-23 (B:9-23), which are known to be a critical self-antigen-driving disease progress in animal models of autoimmune diabetes. These B:9-23-specific T cells from islets responded to whole proinsulin and islets, whereas previously identified B:9-23 responsive clones from peripheral blood did not, highlighting the importance of proinsulin-specific T cells in the islet microenvironment.
Assuntos
Autoantígenos/imunologia , Linfócitos T CD4-Positivos/imunologia , Diabetes Mellitus Tipo 1/imunologia , Insulina/imunologia , Ilhotas Pancreáticas/imunologia , Fragmentos de Peptídeos/imunologia , Proinsulina/imunologia , Precursores de Proteínas/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Adolescente , Peptídeo C/imunologia , Criança , Feminino , Antígenos HLA-DQ/imunologia , Antígenos HLA-DR/imunologia , Humanos , Células Secretoras de Insulina , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/patologia , Receptores de Antígenos de Linfócitos T/genética , Adulto JovemRESUMO
OBJECTIVE: To explore whether electrochemiluminescence (ECL) assays can help improve prediction of time to type 1 diabetes in the TrialNet autoantibody-positive population. RESEARCH DESIGN AND METHODS: TrialNet subjects who were positive for one or more autoantibodies (microinsulin autoantibody, GAD65 autoantibody [GADA], IA-2A, and ZnT8A) with available ECL-insulin autoantibody (IAA) and ECL-GADA data at their initial visit were analyzed; after a median follow-up of 24 months, 177 of these 1,287 subjects developed diabetes. RESULTS: Univariate analyses showed that autoantibodies by radioimmunoassays (RIAs), ECL-IAA, ECL-GADA, age, sex, number of positive autoantibodies, presence of HLA DR3/4-DQ8 genotype, HbA1c, and oral glucose tolerance test (OGTT) measurements were all significantly associated with progression to diabetes. Subjects who were ECL positive had a risk of progression to diabetes within 6 years of 58% compared with 5% for the ECL-negative subjects (P < 0.0001). Multivariate Cox proportional hazards models were compared, with the base model including age, sex, OGTT measurements, and number of positive autoantibodies by RIAs. The model with positivity for ECL-GADA and/or ECL-IAA was the best, and factors that remained significantly associated with time to diabetes were area under the curve (AUC) C-peptide, fasting C-peptide, AUC glucose, number of positive autoantibodies by RIAs, and ECL positivity. Adding ECL to the Diabetes Prevention Trial risk score (DPTRS) improved the receiver operating characteristic curves with AUC of 0.83 (P < 0.0001). CONCLUSIONS: ECL assays improved the ability to predict time to diabetes in these autoantibody-positive relatives at risk for developing diabetes. These findings might be helpful in the design and eligibility criteria for prevention trials in the future.
Assuntos
Autoanticorpos/sangue , Diabetes Mellitus Tipo 1/diagnóstico , Progressão da Doença , Luminescência , Adolescente , Adulto , Glicemia/metabolismo , Peptídeo C/sangue , Criança , Diabetes Mellitus Tipo 1/sangue , Feminino , Hemoglobinas Glicadas/metabolismo , Humanos , Anticorpos Anti-Insulina/sangue , Estudos Longitudinais , Masculino , Modelos de Riscos Proporcionais , Estudos Prospectivos , Fatores de Risco , Fatores de Tempo , Adulto JovemRESUMO
We tested the hypothesis that alterations in the intestinal microbiota are linked with the progression of type 1 diabetes (T1D). Herein, we present results from a study performed in subjects with islet autoimmunity living in the U.S. High-throughput sequencing of bacterial 16S rRNA genes and adjustment for sex, age, autoantibody presence, and HLA indicated that the gut microbiomes of seropositive subjects differed from those of autoantibody-free first-degree relatives (FDRs) in the abundance of four taxa. Furthermore, subjects with autoantibodies, seronegative FDRs, and new-onset patients had different levels of the Firmicutes genera Lactobacillus and Staphylococcus compared with healthy control subjects with no family history of autoimmunity. Further analysis revealed trends toward increased and reduced abundances of the Bacteroidetes genera Bacteroides and Prevotella, respectively, in seropositive subjects with multiple versus one autoantibody. Canonical discriminant analysis suggested that the gut microbiomes of autoantibody-positive individuals and seronegative FDRs clustered together but separate from those of new-onset patients and unrelated healthy control subjects. Finally, no differences in biodiversity were evident in seropositive versus seronegative FDRs. These observations suggest that altered intestinal microbiota may be associated with disease susceptibility.
Assuntos
Bactérias/classificação , Diabetes Mellitus Tipo 1/etiologia , Microbioma Gastrointestinal/fisiologia , Ilhotas Pancreáticas/imunologia , Adolescente , Adulto , Autoanticorpos/sangue , Autoimunidade , Estudos de Casos e Controles , Criança , Pré-Escolar , Estudos de Coortes , Suscetibilidade a Doenças , Fezes/microbiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , RNA Ribossômico 16S/química , RNA Ribossômico 16S/genética , Estados Unidos , Adulto JovemRESUMO
Although dogma predicts that under normal circumstances, potentially offensive autoreactive cells are silenced by mechanisms of immune tolerance, islet antigen-reactive B lymphocytes are known to play a crucial role in the development of autoimmunity in type 1 diabetes (T1D). Thus, participation of these cells in T1D may reflect escape from silencing mechanisms. Consistent with this concept, we found that in healthy subjects, high-affinity insulin-binding B cells occur exclusively in the anergic naive IgD(+), IgM(-) B-cell (BND) compartment. Antigen receptors expressed by these cells are polyreactive and have N-region additions, Vh usage, and charged complementarity-determining region 3 consistent with autoreactivity. Consistent with a potential early role in autoimmunity, these high-affinity insulin-binding B cells are absent from the anergic compartment of some first-degree relatives and all prediabetic and new-onset (<1 year) T1D patients tested, but return to normal levels in individuals diabetic for >1 year. Interestingly, these changes were correlated by transient loss of the entire BND compartment. These findings suggest that environmental events such as infection or injury may, by disrupting B-cell anergy, dispose individuals toward autoimmunity, the precise nature of which is specified by genetic risk factors, such as HLA alleles.