Triggers of autoimmunity. Studies on gestational events.

Objective The primary aim of this thesis was to test whether gestational exposure to environmental factors may induce islet autoimmunity. The second aim was to determine to what extent the exposure to viruses or other environmental factors is a risk factor for type 1 diabetes in the offspring. As children with type 1 diabetes have a higher risk of developing celiac disease (CD), an additional aim was to determine whether markers of possible infections during early pregnancy was associated with development of tissue transglutaminase (tTG) autoantibodies or CD in the offspring. These aims have been summarized in four independent studies. Study population and Methods The Diabetes Prediction in Skåne (DiPiS) is a population based study where blood samples were obtained at the time of delivery between September 2000 and August 2004 from all mothers in this region (Skåne). The blood samples were analyzed for HLA-DQ alleles and islet autoantibodies. The prospective cohort study Celiac Disease Prediction in Skåne (CiPiS) is part of the DiPiS study, which aims to determine the etiology indicators of celiac disease (CD) in newborn children. Children with HLA-risk alleles associated with CD were screened for tissue transglutaminase autoantibodies (tTGA). CD was established by intestinal biopsy in children with confirmed tTGA. Early pregnancy serum samples (gestational week 10-16) were collected from the Southern Sweden Microbiological biobank (SSM-Biobank). This biobank contains more than 120,000 stored plasma samples that have been obtained between 1986 and 2009 from all pregnant mothers at their first visit to the Maternity Care Center. By combining the SSM-Biobank with DiPiS and CiPiS, a total of 24,000 mothers were identified. All mothers included in this thesis (n=1,748) were analyzed for HLA genotype, islet autoantibodies (GADA, IA-2A and IAA in both early pregnancy samples and at delivery), nine different cytokines, one chemokine (early pregnancy samples), IgM class enterovirus (EV) antibodies and EV-RNA (early pregnancy samples). Study I-IV Study I: The objective of our first study was to determine seroconversion to islet autoantibodies in non-diabetic mothers during pregnancy. This was achieved by analyzing end point titers of GADA, IA-2A and IAA in both early pregnancy samples and samples at delivery. Mother’s positive for GADA (92%), IA-2A (84%) or IAA (65%) at delivery had increased titers already in early pregnancy. Titers declined for GADA (p<0.0001), IA-2A (p<0.0001) and IAA (p<0.0001). Seroconversion during pregnancy was observed for GADA in 10 (8%), IA-2A in 3 (16%) and IAA in 37 (35%) mothers. Study II: In this study, we collected early pregnancy serum samples from mothers who later gave birth to children who developed high titers of tTGA or confirmed CD. We then measured an array of Th1/Th2 cytokines (nine cytokines and one chemokine) with the aim of investigating whether CD is triggered already in utero as denoted by quantitative changes in the mother’s cytokine profile. We observed that levels of seven out of ten cytokines were significantly increased in mothers who gave birth to children with CD when compared to controls. Study III: As studies have shown that unbalanced gestational cytokine profiles have been associated with maternal autoimmune disease, preeclampsia, and recurrent spontaneous abortions we analyzed in the present study cytokines in serum samples collected during early pregnancy from mothers who gave birth to children developing multiple, persistent islet autoantibodies, type 1 diabetes, or both, before seven years of age. We found that IFN-γ (p=0.02) and IL-1β (p=0.04) were elevated in the index mothers. All cytokines except IL-4 were highly correlated (p