| 1. |
- Skoglund, Camilla, 1977-
(författare)
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Autoantibodies related to type 1 diabetes in children
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes is an autoimmune disease resulting from destruction of the insulin producing beta cells in the pancreas. The patients need life-long heavy treatment and still complications, both acute and later in life, are common. The incidence of type 1 diabetes has increased rapidly during the last decades, especially among young children. The disease can be predicted by genes predisposing type 1 diabetes, mainly human leukocyte antigen (HLA) genes, together with presence of autoantibodies to beta-cell antigens, where multiple autoantibodies confer the highest risk. A number of immune system intervention trials are now ongoing aiming to halt the progression of the inflammatory process in the beta cells.This thesis aimed to investigate the prevalence and levels of autoantibodies in healthy children and in children with type 1 diabetes. Another aim was to study different properties of one of these autoantibodies, such as to which epitopes the antibodies bind and the distribution of immunoglobulin (Ig)-G subclasses, after immunomodulatory treatment in children with type 1 diabetes.We found that positivity to autoantibodies against glutamic acid decarboxylase (GADA) and tyrosine phosphatase like protein islet antigen-2 (IA-2A) was associated with HLA risk genotypes in 5-year old children from the general population. HLA risk genotypes seemed important for persistence of autoantibodies and for development of type 1 diabetes, while emergence of autoantibodies, especially transient autoantibodies, seemed to be more influenced by environmental factors. Improved methods for detection of autoantibodies are needed, for prediction of diabetes and for identification of high-risk individuals suitable for prevention treatments. Therefore, an assay for measurement of insulin autoantibodies (IAA), based on surface plasmon resonance (SPR), was developed. The main advantages of this method are that there is no need for labelling and that it is time-saving compared to the traditionally used radioimmunoassay (RIA), but further development of the method is needed.Treatment with GAD-alum (Diamyd) in children with type 1 diabetes has shown to preserve residual insulin secretion. This clinical effect was accompanied by an increase in GADA levels. We investigated the epitope reactivity of GADA in both GAD-alum and placebo treated children, and found that binding to one of the tested epitopes was temporarily increased after injection of GAD-alum. This result suggests that the quality of GADA was, to some extent, transiently affected by the treatment. On the other hand, no changes in binding to epitopes associated with stiff person syndrome (SPS) were observed, which together with the lack of change in GAD65 enzyme activity further strengthens the safety of the treatment. We also observed that the distribution of IgG subclasses was changed by GAD-alum treatment, with a lower proportion of IgG1 and higher IgG3 and IgG4. Lower IgG1 and higher IgG4 suggest a temporary switch towards a protective Th2 immune response, which has previously been observed in the same individuals for other immunological markers.In conclusion, measurement of autoantibodies related to type 1 diabetes is an important tool for studying the autoimmune process in pre-diabetic and type 1 diabetic children. In addition to the use as markers of disease progression, the autoantibodies may be used for studying the effects of immunomodulatory treatments on the humoral immune response.
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| 2. |
- Pihl, Mikael, 1981-
(författare)
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Reign in Blood : Immune Regulation in Type 1 Diabetes
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 Diabetes (T1D) is an autoimmune disease resulting in insulin deficiency as a result ofautoimmune destruction of pancreatic β-cells. Preserving β-cell function in patients with T1D would be of great benefit since patients with sustained endogenous insulin secretion are known to suffer less from secondary complications due to hyperglycemia. Glutamic acid decarboxylase 65 (GAD65) is a major autoantigen targeted by self-reactive lymphocytes in T1D, and has been used in several attempts at treating T1D by inducing tolerance to β-cell antigens. We showed positive clinical effects of GAD65 formulated with aluminium hydroxide (GAD-alum) on preservation of C-peptide secretion in a phase II clinical trial. Unfortunately, a phase III clinical trial in a larger population failed to confirm this finding. Regulatory T cells (Treg) are instrumental in maintaining peripheral tolerance to self-antigens. Deficiencies in Treg function are thought to influence the pathogenesis of autoimmune diseases, including T1D. One proposed mechanism of achieving tolerance to β-cell antigens in T1D is the induction of antigen-specific Treg through immunomodulation. The general aim of this thesis was to study immune regulation in T1D, the role of Treg and immunomodulatory effects of GAD-alum treatment in particular. Our hypothesis was that Treg biology is altered in T1D and pre-diabetes, and that an induction of GAD65-specific Treg contributes to the clinical efficacy of GAD-alum treatment. We demonstrated that T cells expressing Treg-associated markers were increased in number in patients with recent-onset T1D, as well as in children with high risk of developing T1D. We found that antigen recall 4 years after GAD-alum treatment induced cells with both regulatory and effector phenotypes in GAD-alum treated patients. Furthermore there was no effect on Treg-mediated suppression in GAD-alum treated patients, while patients with T1D, regardless of treatment, exhibited deficient Treg-mediated suppression of Teff that was intrinsic to the Treg population. We followed patients participating in a phase III trial of GAD-alum, and using an extended antibody panel we demonstrated that antigen recall induced mainly Teff cells in treated patients, along with increased frequencies of memory T cells, non-suppressive CD45RA-FOXP3lo cells and increased GAD65-induced proliferation of mainly Teff and memory T cells. Finally we examined whether SNPs in genes encoding inflammasome components contributed to T1D risk, but found no effects of variant alleles on the risk of developing T1D, or on the efficacy of GAD-alum treatment. We show small effects on C-peptide secretion and autoantibody positivity in patients with T1D. In conclusion, we find that while Treg are deficient in patients with T1D, induction of Treg is an unlikely mechanism of action of GAD-alum treatment.
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| 3. |
- Åkerman, Linda, 1983-
(författare)
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Aspects of the Pre-Diabetic Period in Type 1 Diabetes
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes (T1D) is an autoimmune disease characterized by insulin deficiency, due to immune-mediated destruction of beta cells. Current knowledge regarding the period preceding disease onset comes, to a large extent, from studying risk cohorts based on relatives of T1D-patients, as they have an increased disease risk. Among T1D patients in general, however, few have the disease in their immediate family. It is therefore important to study risk cohorts from the general population as well. An ongoing autoimmune reaction can often be seen in the blood long before disease onset, by detection of autoantibodies directed towards beta cell antigens. By autoantibody screening among participants in the ABIS (All Babies in the South-east of Sweden) cohort, we could identify a group of children from the general population with increased risk for T1D, positive for multiple autoantibodies. They were enrolled in a 2-year prospective follow-up aiming to characterize the prediabetic period and to identify factors indicative of progression/non-progression to T1D. We assessed glucose homeostasis and autoantibody titers over time, and searched for risk-biomarkers by analyzing the expression of immune-related genes (Th1-Th2-Th3) in peripheral blood mononuclear cells (PBMC) from these children, in comparison to healthy children and newly diagnosed T1D patients. In the same groups we also compared serum micro RNA (miRNA) profiles, knowing that miRNA molecules have desirable biomarker properties. We found that two specific autoantibodies, IA2A and ZnT8A, were detected at higher concentrations in risk-individuals who progressed to overt T1D during or after the follow-up period, compared to those who still have not. We also observed disturbed glucose homeostasis long before onset in the progressors, but it was seen among those who remain symptom free as well. Further, we found support for the possible role of insulin resistance as an accelerator of the disease process. For gene expression and serum miRNA, few differences were observed between risk-individuals and healthy children overall. However, for PBMC gene expression and serum miRNA both, there were associations to beta cell function and glucose homeostasis, and for miRNA also to islet autoantibodies. Although specific profiles for prediction of disease onset or identification of risk-individuals could not be found, these results are interesting and deserve to be evaluated further. As part of another sub-study within ABIS, the effects of physical activity on glucose homeostasis were assessed in healthy schoolchildren. The level of physical activity, measured by pedometers, was related to insulin resistance and beta cell-stress, and decreased physical activity was associated with increased insulin resistance and load on the insulin-producing beta cells, already at school-age.
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