| 1. |
- Knip, Mikael, et al.
(författare)
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Environmental triggers and determinants of type 1 diabetes
- 2005
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Ingår i: Diabetes. - 0012-1797 .- 1939-327X. ; 54:SUPPL. 2
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Tidskriftsartikel (refereegranskat)abstract
- Type 1 diabetes is perceived as a chronic immune-mediated disease with a subclinical prodromal period characterized by selective loss of insulin-producing β-cells in the pancreatic islets in genetically susceptible subjects. A series of evidence supports a critical role of exogenous factors in the development of type 1 diabetes, such as 1) the fact that <10% of individuals with HLA-conferred diabetes susceptibility do progress to clinical disease, 2) a pairwise concordance of type 1 diabetes of <40% among monozygotic twins, 3) a more than 10-fold difference in the disease incidence among Caucasians living in Europe, 4) a several-fold increase in the incidence over the last 50 years, and 5) migration studies indicating that the disease incidence has increased in population groups who have moved from a low-incidence to a high-incidence region. This article discusses the trigger-booster hypothesis claiming that the diabetic disease process is triggered by an exogenous factor with definite seasonal variation and driven by one or several other environmental determinants. In addition, there are a series of modifying factors affecting the fate and pace of the process. Accordingly, progression to clinical type 1 diabetes typically requires the unfortunate combination of genetic disease susceptibility, a diabetogenic trigger, and a high exposure to a driving antigen. © 2005 by the American Diabetes Association.
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| 2. |
- Skarsvik, Susanne, 1978-, et al.
(författare)
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Decreased in vitro type 1 immune response against coxsackie virus B4 in children with type 1 diabetes
- 2006
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 55:4, s. 996-1003
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Tidskriftsartikel (refereegranskat)abstract
- Enteroviruses, particularly Coxsackie virus B4 (CVB4), are considered to be involved in the pathogenesis of type 1 diabetes. We wanted to compare the characteristics of T-cell immune response to CVB4 in children with type 1 diabetes and healthy children with and without HLA risk-associated haplotypes (HLA-DR3-DQ2 or HLA-DR4-DQ8) for type 1 diabetes. Peripheral blood mononuclear cells (PBMCs) were isolated and cultured with CVB4 and analyzed for cytokine and chemokine receptors by flow cytometry and for expression of transcription factors Tbet and GATA-3 by RT-PCR and Western blot. Culture supernatants were analyzed for secretion of γ-interferon (IFN-γ). In children with type 1 diabetes, a decreased percentage of T-cells expressed CCR2, CXCR6, interleukin (IL)-18R, and IL-12Rβ2-chain after in vitro stimulation with CVB4 in comparison with healthy children with or without HLA risk genotype. Moreover, we found that children with type 1 diabetes had decreased IFN-γ secretion and expression of Tbet, both on mRNA and protein level, in CVB4-stimulated PBMCs. Accordingly, children with type 1 diabetes show an impaired type 1 immune response against CVB4 compared with healthy children. This may lead to a delayed clearance of the virus and, at least partly, explain why children with type 1 diabetes may be more prone to CVB4 infections and related complications, such as β-cell damage.
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| 3. |
- Vaarala, Outi, 1962-, et al.
(författare)
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Insulin treatment in patients with type 1 diabetes induces upregulation of regulatory T-cell markers in peripheral blood mononuclear cells stimulated with insulin in vitro
- 2006
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 55:12, s. 3446-3454
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Tidskriftsartikel (refereegranskat)abstract
- Patients with type 1 diabetes are treated with daily injections of human insulin, an autoantigen expressed in thymus. Natural CD4+CD25high regulatory T-cells are derived from thymus, and accordingly human insulin-specific regulatory T-cells should exist. We had a chance to study peripheral blood mononuclear cells (PBMCs) from children with type 1 diabetes both before and after starting insulin treatment, and thus we could analyze the effects of insulin treatment on regulatory T-cells in children with type 1 diabetes. PBMCs were stimulated for 72 h with bovine/human insulin. The mRNA expression of regulatory T-cell markers (transforming growth factor-β, Foxp3, cytotoxic T-lymphocyte antigen-4 [CTLA-4], and inducible co-stimulator [ICOS]) or cytokines (γ-interferon [IFN-γ], interleukin [IL]-5, IL-4) was measured by quantitative RT-PCR. The secretion of IFN-γ, IL-2, IL-4, IL-5, and IL-10 was also studied. The expression of Foxp3, CTLA-4, and ICOS mRNAs in PBMCs stimulated with bovine or human insulin was higher in patients on insulin treatment than in patients studied before starting insulin treatment. The insulin-induced Foxp3 protein expression in CD4+CD25 high cells was detectable in flow cytometry. No differences were seen in cytokine activation between the patient groups. Insulin stimulation in vitro induced increased expression of regulatory T-cell markers, Foxp3, CTLA-4, and ICOS only in patients treated with insulin, suggesting that treatment with human insulin activates insulin-specific regulatory T-cells in children with newly diagnosed type 1 diabetes. This effect of the exogenous autoantigen could explain the difficulties to detect in vitro T-cell proliferation responses to insulin in newly diagnosed patients. Furthermore, autoantigen treatment-induced activation of regulatory T-cells may contribute to the clinical remission of the disease. © 2006 by the American Diabetes Association.
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