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- Andersson, Annika K., et al.
(författare)
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Cytokine-induced PGE2 formation is reduced from iNOS deficient murine islets
- 2004
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Ingår i: Molecular and Cellular Endocrinology. - : Elsevier BV. - 0303-7207 .- 1872-8057. ; 220:1-2, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- Cytokines may be involved in islet destruction during Type 1 diabetes. Exposure to interleukin-1beta (IL-1beta) or IL-1beta plus interferon-gamma (IFN-gamma) of rodent islets induces expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Subsequent formation of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) may impair beta-cell function. Using iNOS deficient (iNOS -/-) islets, we have further investigated the relation between NO formation and PGE(2) induction. We found that iNOS -/- islets responded with a reduced PGE(2) formation following IL-1beta or (IL-1beta + IFN-gamma) treatment compared to wild-type (wt) islets, while COX-2 mRNA or protein content were unchanged. By the addition of an NO donor together with IL-1beta, PGE(2) formation could be stimulated from iNOS -/- islets. We conclude that the lowered capacity of PGE(2) formation observed from cytokine exposed iNOS -/- islets is due to a decreased stimulation of PGE(2) formation by the COX-2 enzyme in the absence of NO, rather then differences in expressed COX-2 protein.
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- Andersson, Annika K., 1974-
(författare)
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Role of Inducible Nitric Oxide Synthase and Melatonin in Regulation of β-cell Sensitivity to Cytokines
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The mechanisms of β-cell destruction leading to type 1 diabetes are complex and not yet fully understood, but infiltration of the islets of Langerhans by autoreactive immune cells is believed to be important. Activated macrophages and T-cells may then secrete cytokines and free radicals, which could selectively damage the β-cells. Among the cytokines, IL-1β, IFN-γ and TNF-α can induce expression of inducible nitric synthase (iNOS) and cyclooxygenase-2. Subsequent nitric oxide (NO) and prostaglandin E2 (PGE2) formation may impair islet function.In the present study, the ability of melatonin (an antioxidative and immunoregulatory hormone) to protect against β-cell damage induced by streptozotocin (STZ; a diabetogenic and free radical generating substance) or IL-1β exposure was examined. In vitro, melatonin counteracted STZ- but not IL-1β-induced islet suppression, indicating that the protective effect of melatonin is related to interference with free radical generation and DNA damage, rather than NO synthesis. In vivo, non-immune mediated diabetes induced by a single dose of STZ was prevented by melatonin.Furthermore, the effects of proinflammatory cytokines were examined in islets obtained from mice with a targeted deletion of the iNOS gene (iNOS -/- mice) and wild-type controls. The in vitro data obtained show that exposure to IL-1β or (IL-1β + IFN-γ) induce disturbances in the insulin secretory pathway, which were independent of NO or PGE2 production and cell death. Initially after addition, in particular IL-1β seems to be stimulatory for the insulin secretory machinery of iNOS –/- islets, whereas IL-1β acts inhibitory after a prolonged period. Separate experiments suggest that the stimulatory effect of IL-1β involves an increased gene expression of phospholipase D1a/b. In addition, the formation of new insulin molecules appears to be affected, since IL-1β and (IL-1β + IFN-γ) suppressed mRNA expression of both insulin convertase enzymes and insulin itself.
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- Karlsson, Maria G. E.
(författare)
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The Importance of Cell-Mediated Immunity for the Development of Type 1 Diabetes
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background Type I (insulin-dependent) diabetes mellitus is an autoimmune disease characterised by infiltration of T-lymphocytes in the islets of Langerhans. In particular, activated Th1-like lymphocytes secreting IFN-γ are suggested to contribute to the inflammatory process and the destruction of ß-cells, whereas Th2-like cells producing IL-4 might even be protective. Environmental factors (diet, viruses, stress etc.) and autoantigens, e.g. Glutamic Acid Decarboxylase (GAD65) and insulin, are suggested to initiate the autoimmune process resulting in type I diabetes.Aim To estimate the immunological balance of Th1/Th2-like lymphocytes, spontaneously and after stimulation with antigens, in high-risk first degree relatives of type 1 diabetic children and in children with newly diagnosed type 1 diabetes.Materials and methods Peripheral blood mononuclear cells (PBMC) from healthy high-risk first-degree relatives (ICA ≥ 20) and newly diagnosed type 1 diabetic children were examined and compared with the response seen in PBMC from healthy controls matched for age and HLA-type (DR3 and/or DR4).Expression of IFN-γ and IL-4 mRNA was determined by RT-PCR or real-time RTPCR and IFN-γ and IL-4 by ELISPOT or ELISA, spontaneously and after stimulation with GAD65 , insulin, bovine serum albumin (BSA), the ABBOS-peptide and ß-lactoglobulin (ßLG). Cytokine expression and secretion was compared to the production of diabetes-associated autoantibodies and to the secretion of endogenous insulin.Results The epitope of GAD65, that mimics the Coxsackie B virus, caused increased IFN-γ mRNA expression in activated Th1-like lymphocytes from newly diagnosed diabetic children. This suggests that GAD65 might be involved in the development of type I diabetes. On the contrary, cow's milk proteins caused increased IFN-γ and IL- 4 mRNA expression in activated Th1- and Th2-like lymphocytes from both diabetic and healthy children. This does not support the hypothesis that cow's milk antigens are important for the development of type 1 diabetes.Overwhelming secretion of IFN-γ was observed in high-risk first-degree relatives of type 1 diabetic children. High-risk individuals still have the ability to change a Th1-like immune deviation into a more protective Th2-like response in the presence of GAD65 and insulin.Conclusions GAD65, but not cow's milk proteins, causes a Th1-like deviation in type 1 diabetic children. High-risk individuals are capable to deviate a Th1-like immune system into a more protective Th2-like response in the presence of autoantigens. These results can be useful in future therapeutic approaches.
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