| 1. |
- Axelsson, Stina, 1981-
(author)
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GAD65 An Immunomodulator in Type 1 Diabetes
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Type 1 diabetes (T1D) is caused by a deficiency of insulin as a result of an autoimmune destruction of the pancreatic ² -cells. A possibility to preserve remaining ² -cells in children with newly diagnosed T1D is of great importance since sustained ² -cell function is recognized to result in reduced end-organ complications. Glutamic acid decarboxylase 65 (GAD65) is one of the major antigens targeted by self-reactive T cells in T1D, and immunomodulation with GAD65 formulated in aluminum (GAD-alum) has been considered both in prevention and treatment of T1D. Results from a Phase II trial have shown clinical effect of subcutaneous injections with GAD-alum, this was unfortunately not fully confirmed in the following larger Phase III trial which therefore was closed after 15 months. The general aim of this thesis was to study the immunomodulatory effect of GAD-alum-treatment in children with T1D participating in the Phase II and Phase III trials. We hypothesized that treatment with GAD-alum contributes to the preservation of residual insulin secretion through deviation of the GAD65-specific immune response from a destructive to a protective process, accompanied by a shift from T helper (Th) 1 towards a predominant Th2 profile. In the Phase II trial, GAD-alum-treated patients responded with an early GAD65-specific Th2 skewed cytokine secretion, with highest IL-5 and IL-13 secretion in clinical responders. Also, the CCR4/CCR5 ratio indicating balance between Th2/Tc2 and Th1/Tc1 responses, increased in treated patients. The recall response to GAD65 was characterized by a wide range of cytokines, but the relative contribution of each cytokine suggests a shift towards a more pronounced Th2-associated profile over time. Induction of a CD4+ cell subset upon GAD65-stimulation 4 years after treatment, suggesting clonal expansion of the memory T-cell compartment upon antigen re-challenge, was seen in parallel to a persistent GAD65-specific cytokine response. Finally, even if the phase III trial failed to reach the primary endpoint at 15 months, a subgroup analysis showed that the treatment had an effect on preservation of residual insulin secretion, but the effect was not seen until after 30 months. Taken together, these results suggest that GAD-alum treatment might exert its effect through induction of an early Th2 skewed immune response which tends to deviate away from a destructive Th1/Tc1 response upon GAD65 re-challenge, and generation of GAD65-specific memory T cells that produce cytokines and exert effector responses which may be important for regulating GAD65 immunity. Continued research to better understand how immunomodulation with autoantigen modifies T-cell responses and also which patients are suitable for treatment, is crucial for optimizing future intervention trials using ² -cell antigens.
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| 2. |
- Kindgren, Erik, 1977-
(author)
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Early Life Environmental Risk Factors and Gut Microbiota in Juvenile Idiopathic Arthritis : - More than a gut feeling
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Background: The autoimmune disease juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in children, but the cause is not fully established. Only a small percentage (13–18%) of the risk of contracting the disease can be attributed to genetic factors, but environmental factors are believed to be behind most of the risk. An unfavourable composition of gut bacteria has also been suggested as a factor that may increase the risk of developing JIA. Aims: The main aim of this thesis was to study risk factors during fetal life and in the early childhood environment for future onset of JIA. A further aim was to study the composition and importance of the gut microbiota before the onset of JIA. Methods: In the ABIS study, a population-based prospective birth cohort of 17,055 children, data were collected on environmental factors during pregnancy and childhood. We identified 111 individuals with a JIA diagnosis. Environmental factors were mainly analysed using multivariable logistic regression, with adjustment for confounding factors. The microbiome at one year of age was analysed from stool samples by 16S rRNA PCR. Results: Significant associations could be noted between mode of birth, duration of breastfeeding, birth order and exposure to antibiotics or fish early in life with future onset of JIA. These risk factors were found to pose an even higher cumulative risk if several of the factors were present. Carrying a risk allele in combination with being exposed to a specific environmental factor further increased the risk. In addition, several taxa were identified in the gut microbiota at one year that were associated with future onset of JIA. Many of these taxa were associated with one or more of the identified early childhood environmental risk factors. Conclusion: In these studies, it has been demonstrated that children with JIA have, very early in life, already been exposed to negative environmental factors (caesarean section, short-term breastfeeding, being firstborn and being exposed to antibiotics or fish during the first year of life). The effect from these risk factors appears to be to some extent mediated via a changed composition of the gut microbiota. An environmentally induced dysregulation of the microbiome can trigger or accelerate the development of JIA in genetically predisposed children.
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| 3. |
- Lahdenperä, Anne, 1974-
(author)
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Studies of Mucosal Immune Regulation in Celiac Disease and Type 1 Diabetes
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Background: Celiac disease (CD) and type 1 diabetes (T1D) are two chronic autoimmune diseases with increasing incidence worldwide. A combination of genetic, environmental and immunological factors is considered to be involved in development of the diseases, even though the exact disease mechanisms still are unknown. CD and T1D are both believed to be associated with type 1 like immune responses. However, there is limited knowledge about the complex network of intestinal and peripheral immune responses associated with the diseases.Aims: The aim of this thesis was to explore intestinal and peripheral immune responses in children at different stages of CD and in children with T1D. Further, we studied peripheral immune responses in children at risk for T1D supplemented with probiotics during their first 6 months of life (PRODIA study).Results & Discussion: Children with untreated CD had up-regulated T-helper (Th)1, T-cytotoxic (Tc)1, Th17 and T-regulatory (Treg) responses, but down-regulated Th2 and Th3 responses in the small intestine. The type 1 response (Th1 and Tc1) seemed to remain elevated in CD children under gluten free diet (GFD)-treatment and thus seemed to be related to the disease itself rather than the gluten intake. The Th2, Th3, Th17 and Treg responses seemed to be gluten dependent, since they normalized upon GFD-treatment. The alterations in the intestinal biopsies did not seem to correlate with the alterations seen in the blood Children with potential CD had diminished levels of the Th17 cytokine IL-17, whereas children with untreated CD had elevated levels of IL-17, indicating that IL-17 immunity develops in the late phase of CD when villous atrophy has developed. Furthermore, stimulation of intestinal epithelial cells with IL-17 induced anti-apoptotic mechanisms. The low intestinal expression of Th1, Th17 and Treg markers was normal in children with T1D, whereas children with T1D and CD had the same pattern as children with untreated CD: high intestinal secretion of pro-inflammatory and Th17 cytokines. The immune responses in children with T1D were generally influenced by the degree of villous atrophy.As expected, the number of children in the PRODIA study developing T1D related autoantibodies during their first two years of life was low. No difference in the autoantibody emergence was seen between infants given probiotics compared to placebo. In the probiotic group, the number of circulating CD58+ monocytes was lower at 6 months of age. At 12 months of age the number of circulating CCR5+ monocytes was lower in the probiotic group, whereas the spontaneous expression of TLR9 on PBMCs was higher.Conclusion: Most of the intestinal T-cell associated immune alterations were generally gluten dependent, since they normalized on a GFD treatment, but the type 1 response seemed to be related to the disease itself, since it was still seen in GFD treated individuals. IL-17 immunity seemed to be induced in the late stage of CD, when villous atrophy has developed and it seemed to be involved in protection from tissue damage in the inflamed intestinal mucosa. The intestinal immune responses were generally not reflected in peripheral blood.Probiotic supplementation in infancy modulated the activation stage and stimulation response of monocytes. Thus, early exposure to microbes seemed to influence the function of the innate immune system in later life.
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| 4. |
- Chéramy, Mikael
(author)
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Characteristics of GADA in Type 1 Diabetes following Immunomodulation with GAD65
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Type 1 diabetes (T1D) is a serious autoimmune disease which increases worldwide and affects children at a young age, but there still is no cure available. Clinical intervention trials in recent onset T1D patients are therefore very important, since even a modest preservation of β-cell function has proven to reduce end-organ complications. Glutamic acid decarboxylase 65 (GAD65) is one of the major antigens in T1D, to which autoantibodies (GADA) are formed. Immunomodulation with aluminum-formulated GAD65 (GAD-alum) has been considered both in the prevention and intervention of T1D. In a phase II trial using GADalum we showed clinical benefits in C-peptide preservation, but unfortunately a following larger European phase III trial failed to reach primary end-point. The general aim of this thesis was to study the characteristics and phenotypes of GADA following immunomodulation with GAD-alum in T1D patients during a phase II and III trial.In the phase II trial, a transient increase of the GADA IgG3 and IgG4 subclasses, and a decrease in IgG1 was detected as part of the treatment-induced GADA levels after 2 GADalum doses, a result interpreted to be T helper (Th) 2-associated. This Th2-associated immune response was also observed, in parallel to increased GADA levels, during the following phase III trial including a larger group of patients. However, enhanced Th2-like IgG subclass distribution, reflected as increased IgG4 frequency, was in contrast only observed in the group treated with 4 doses of GAD-alum. In addition, the GADA fold-change was associated with in vitro GAD65-stimulated cytokine secretion, but only in patients receiving 2 GAD-alum doses. Furthermore, a 4-year follow-up of the phase II trial showed that the effect of GAD-alum treatment was long-lasting as GADA titers remained elevated. Even though the phase III trial did not reach primary end-point, and was closed after 15 months, preservation of β-cell function was observed in the small sub-group of Swedish patients receiving 2 GAD-alum doses that completed the 30 months trial-period. During the trials, concerns were raised whether the elevated GADA titers might induce Stiff person syndrome (SPS), a disease affecting the nervous system, but in vitro analysis of GADA phenotypes showed that the GAD65-enzyme activity and GADA epitope distribution differed from that detected in SPS patients.Continued research to clarify how immunomodulation with autoantigens affects immune responses and also to identify which patients are suitable for treatment, is crucial for optimizing future T1D intervention- and prevention trials.
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