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- Skarsvik, Susanne, 1978-
(författare)
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Aberrancies associated with dendritic cells and T lymphocytes in type 1 diabetes
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The incidence of type 1 diabetes has rapidly increased in the Western world and the age of onset has shifted to younger ages. Type 1 diabetes is a chronic disease caused by destruction of the insulin producing ß-cells in the pancreas leading to severe insulin deficiency. This results in hyperglycaemia and diagnosis of overt type 1 diabetes.The pathogenesis of type 1 diabetes is not fully understood. When diagnosed during childhood, the ß-cell destruction is believed to be caused by autoreactive T cells in the majority of cases. The effect of autoreactive T cells is limited by dendritic cells, which are involved in the induction of tolerance and in regulating T cells. Different subsets of T cells also play a role in regulating immune responses. The activation of autoreactive T cells is believed to be triggered by environmental factors e.g. coxsackievirus B4 and/or dietary factors. The major genetic determinant for type 1 diabetes is associated with the HLA class II genes encoding the HLA molecules on antigen presenting cells.The aim of the present study was to study the maturation of dendritic cells and how T cell reactivity is influenced by genetic and environmental factors in children with type 1 diabetes and/or children with increased genetic risk of developing type 1 diabetes in comparison to healthy children.The maturation of dendritic cells was studied by in vitro differentiation of monocytes into dendritic cells. Our results showed that children with type 1 diabetes and those with genetic risk of type 1 diabetes had a lower percentage of dendritic cells expressing CD11c and HLA-DR in addition to decreased secretion of TNF.The regulation of T cell polarization was investigated in children with type 1 diabetes and in neonates at genetic risk of type 1 diabetes by in vitro polarization of T cells. Children with newly diagnosed and longstanding type 1 diabetes had a lower number of CD4 and CD8 T cells expressing IL-12Rß2-chain and increased secretion of IL-13 from lymphocytes cultured in type 1 cytokine environment in comparison to healthy children. Neonates carrying type 1 diabetes risk associated haplotypes DQ2/DQ8 or DQ8 had a lower percentage of CD4 T cells expressing CCR4, lower mRNA levels of CCR4 and GATA-3 and lower secretion of IL-13 in lymphocytes cultured in type 2 cytokine environment compared to neonates without genetic risk of type 1 diabetes. Furthermore, we found that children with type 1 diabetes had a lower percentage of CD4 and CD8 T cells expressing CCR2, CXCR6 and IL-18R after in vitro stimulation of peripheral blood mononuclear cells with coxsackievirus B4 in comparison to healthy children with and without genetic risk of type 1 diabetes. We also found decreased secretion of IFN-γ and lower levels of Tbet mRNA from peripheral blood mononuclear cells stimulated with coxsackievirus B4 in children with type 1 diabetes compared to healthy children with and without genetic risk of type 1 diabetes.In conclusion, defects in the function of dendritic cells and in the polarization of T cells may contribute to an underlying immunological environment, which allows autoimmune responses to develop and impair the host defence mechanisms against pathogens. Ultimately these immunological aberrancies may lead to development of ß-cell autoimmunity.
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| 2. |
- Skarsvik, Susanne, 1978-, et al.
(författare)
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Aberrant regulation of interleukin-12 receptor β2 chain on type 1 cytokine-stimulated T lymphocytes in type 1 diabetes
- 2005
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Ingår i: Immunology. - : Wiley. - 0019-2805 .- 1365-2567. ; 114:2, s. 287-293
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Tidskriftsartikel (refereegranskat)abstract
- An aberrant mitogen-induced polarization of peripheral blood T cells has been associated with type 1 diabetes (T1D). We studied, in T1D, type 1 and 2 cytokine-induced expression of the interleukin-12 receptor β2 chain (IL-12Rβ2 chain), which plays a critical role in regulating T-cell polarization. Peripheral blood lymphocytes from children with newly diagnosed T1D (n = 10; mean age 10 years), from children with longstanding T1D (n = 8; mean age 12·9 years) and from healthy children (n = 15; mean age 11·5 years) were stimulated with phytohaemagglutinin (PHA) in a type 1 (IL-12 and anti-IL-4) or a type 2 (IL-4 and anti-IL-12) cytokine environment. Secretion of interferon-γ (IFN-γ), IL-5 and IL-13, as detected by enzyme-linked immunosorbent assay (ELISA), and expression of the IL-12Rβ2 chain on CD4 and CD8 cells by flow cytometry, were analysed. Children with newly diagnosed and longstanding T1D had lower expression levels of the IL-12Rβ2 chain on IL-12Rβ2 chain-positive CD4 T cells (for a type 1 or a type 2 cytokine environment: P = 0·01 and P = 0·002 or P = 0·02 and P = 0·01, respectively) and on IL-12Rβ2 chain-positive CD8 T cells (for a type 1 or a type 2 cytokine environment: P = 0·007 and P = 0·0007 or P = 0·003 and P = 0·01, respectively) when compared to healthy children. A decreased percentage of IL-12Rβ2 chain-expressing CD4 T cells (P = 0·07 and P = 0·03) and CD8 T cells (P = 0·004 and P = 0·01) and increased secretion of IL-13 (P = 0·006 and P = 0·04) in a type 1 cytokine environment was seen in both groups of patients. Peripheral blood T cells from patients with both newly diagnosed and longstanding T1D showed poor polarization towards type 1 cells.
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