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Triggers of autoimmunity. Studies on gestational events.

Lindehammer, Sabina LU (2011) In Lund University Faculty of Medicine Doctoral Dissertation Series 2011:57.
Abstract (Swedish)
Popular Abstract in Swedish

Typ 1-diabetes är en allvarlig, autoimmun, sjukdom och Sverige har världens näst högsta antal nya insjuknanden. Varje år diagnostiseras ca 700 individer i Sverige med sjukdomen som kan debutera i alla åldrar. Senare studier tyder dock på att barn med typ 1-diabetes blir allt yngre. Vi vet idag att ärftligheten är kopplad till en specifik gen vilket förklarar ca 30-50% av sjukdomsförekomsten. Detta tyder på att inte bara ärftlighet kan förklara sjukdomen utan någon form av miljöfaktor också krävs för att sjukdomen ska bryta ut.

Glutenintolerans är en annan autoimmun sjukdom som har samma ärftliga faktor som typ 1-diabetes, fast i denna sjukdom känner vi till antigenet, nämligen gluten -... (More)
Popular Abstract in Swedish

Typ 1-diabetes är en allvarlig, autoimmun, sjukdom och Sverige har världens näst högsta antal nya insjuknanden. Varje år diagnostiseras ca 700 individer i Sverige med sjukdomen som kan debutera i alla åldrar. Senare studier tyder dock på att barn med typ 1-diabetes blir allt yngre. Vi vet idag att ärftligheten är kopplad till en specifik gen vilket förklarar ca 30-50% av sjukdomsförekomsten. Detta tyder på att inte bara ärftlighet kan förklara sjukdomen utan någon form av miljöfaktor också krävs för att sjukdomen ska bryta ut.

Glutenintolerans är en annan autoimmun sjukdom som har samma ärftliga faktor som typ 1-diabetes, fast i denna sjukdom känner vi till antigenet, nämligen gluten - en samling proteiner som finns i vete, råg och korn.

I populationsstudien DiPiS (Diabetes Prediktion i Skåne) samlade man in blodprover från kvinnor (DiPiS mammor) i samband med förlossning. Dessa prover påvisade en säsongsberoende variation i mammor som födde barn med autoantikroppar. Dessa autoantikroppar är så kallade markörer för typ 1-diabetes. Dessutom har man visat att mammor som rapporterade infektioner tidigt under graviditeten samt under vintermånaderna, påvisade en ökad risk att föda barn med autoantikroppar. Detta skulle kunna betyda att infektioner är en faktor som påverkar förekomsten av typ 1-diabetes.

Med hjälp av en biobank vid Mikrobiologen i Malmö har vi lyckats identifiera DiPiS-mammor och hämta ut deras blodprov vilka samlades in under deras första besök hos mödravården.

Det övergripande målet med denna avhandling är att undersöka sambandet mellan miljöfaktorer under tidig graviditet och senare förekomst av autoimmunitet hos barnet. Vi testar också möjligheten att exponering för vissa virusstammar (som tillhör gruppen enterovirus) skulle kunna vara en utlösande faktor för autoimmunitet hos barnet. DiPiS-studien och mikrobiologens biobank möjliggjorde våra studier som undersöker förändringar i immunförsvaret hos mamman under tidig graviditet, som senare födde barn vilka utvecklade typ 1-diabetes eller glutenintolerans.



I den första delstudien av avhandlingen undersöker vi förekomst och utveckling av autoantikroppar kopplade till typ 1-diabetes i den gravida mamman. I detta arbete undersöktes inskrivningsprovet från Mikrobiologen i Malmö hos 242 friska mammor vid förlossning av sitt barn, för autoantikroppar mot insulin, GAD65 eller IA-2. Huvudfyndet var att de flesta mammor som födde barn med autoantikroppar hade dessa redan i inskrivningsprovet och nivån av dessa sjönk sedan under resten av graviditeten. Detta är också vanligt med autoantikroppar för andra autoimmuna sjukdomar, där det är välkänt att de sjunker under graviditeten, till exempel ledgångsreumatism. I vår studie var det totalt 50 mammor som utvecklade autoantikroppar under graviditeten.

I det andra delarbetet undersökte vi förändringar i immunförsvaret hos mamman under tidig graviditet, samt om dessa förändringar var kopplade till glutenintolerans hos barnet senare i livet. Inskrivningsprovet från Mikrobiologen i Malmö analyserades för nio cytokiner och en chemokin, vilka alla är immunologiska markörer. Totalt visade sig sju av nio cytokiner vara förhöjda i inskrivningsprovet hos de mammor som födde ett barn som utvecklade glutenintolerans före fem års ålder.

I delarbete tre undersöktes 48 mammor som fött ett barn vilket utvecklade typ-1 diabetes före sju års ålder. Dessa mammors inskrivningsprov undersöktes tillsammans med 93 kontrollmammor för samma immunologiska markörer som i delarbete två. Huvudfynden var att cytokiner som ofta uttrycks i samband med infektioner och som aktiverar den cellulära delen av immunförsvaret återfanns i förhöjda koncentrationer hos de mammor som födde ett barn som utvecklade diabetes före sju års ålder.

I det sista delarbetet analyserades samtliga inskrivningsprover för IgM-antikroppar mot en specifik virusgrupp som kallas för enterovirus. Resultaten visar att ca 10% av mammorna visade tecken på virusexponering redan i inskrivningsprovet. Autoantikroppar återfanns oftare hos de mammor som hade den ärftliga riskfaktorn för både typ-1 diabetes och glutenintolerans. Ett viktigt fynd var att mammor som utvecklade autoantikroppar under graviditeten dvs. var negativa i inskrivningsprovet men positiva vid födseln, var i högre utsträckning positiva för enterovirus IgM-antikroppar i inskrivningsprovet än de som inte utvecklade autoantikroppar under graviditeten. Dessa resultat påvisar att en enterovirusinfektion tidig under graviditeten kan förklara att mammor med ärftlig risk för typ 1-diabetes utvecklar autoantikroppar som är karakteristiska för typ 1-diabetes.

Avhandlingen som presenteras här är den första av sitt slag då den direkt undersöker hur autoantikroppar uppstår under graviditeten och att det finns ett samband mellan inflammatoriska processer vid virusinfektioner och förekomsten av autoimmuna sjukdomar såsom glutenintolerans och typ 1-diabetes hos barnet. Detta fynd stödjer hypotesen att miljöfaktorer som påverkar mamman under tidig graviditet också påverkar det ofödda fostrets framtida hälsa. (Less)
Abstract
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... (More)
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<0.0001).

Study IV: Gestational EV infections have been associated with risk HLA-DR as well as with type 1 diabetes in the child. We analyzed enterovirus RNA (EV-RNA) and IgM (EV-IgM) in relation to type 1 diabetes HLA-DQ risk genotypes and to islet autoantibodies in non-diabetic mothers studied both in early pregnancy and at delivery. EV-IgM, but not EV-RNA was detected during early pregnancy in 12% (44/365) islet autoantibody positive mothers compared to 11% (156/1457) of the controls (p=n.s.). In early pregnancy, mothers with HLA-DQ 2/2 or 2/X genotypes showed, in adjusted logistic regression, an increased risk for islet autoantibodies (OR 1.85, 95% CI 1.34-2.54; p=0.001). EV-IgM was not associated with HLA-DQ in early pregnancy. However, after adjusting for parity, maternal age, year of birth and season of early pregnancy, early pregnancy EV-IgM combined with DQ2/2 or 2/X increased the risk for the mother to be positive for islet autoantibodies at delivery (OR 3.10, 95% CI 1.35-7.15; p=0.008).

Conclusion

From these studies we conclude that pregnant non-diabetic mothers with islet autoantibodies at delivery had significantly higher titers of autoantibodies during early pregnancy than at delivery. As the statistical power in the seroconverting mothers was insufficient, further studies are needed to determine if the risk for type 1 diabetes in the offspring differs between mothers who already had increased titers of islet autoantibodies during early pregnancy or acquired them during pregnancy. Moreover, we conclude that a shift in the Th1/Th2 mediated cytokine pattern during early pregnancy, possibly caused by viral infection may be associated with CD in the offspring. Furthermore, the results from study III suggest that increased levels of IFN-γ and possibly IL-2 during early pregnancy was associated with an increased risk for multiple, persistent islet autoantibodies, type 1 diabetes, or both, before seven years of age in the offspring. Our final study concludes that EV-IgM in early pregnancy increased the risk for islet autoantibodies at delivery in non-diabetic mothers who carry HLA-DQ 2/2 or 2/X type 1 diabetes risk genotypes. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Lars, Stene, Divisjon for Epidemiologi, Nasjonalt folkehelseinstitutt,Oslo, Norge
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Islet autoantibodies, pregnancy, type 1 diabetes, celiac disease
in
Lund University Faculty of Medicine Doctoral Dissertation Series
volume
2011:57
pages
162 pages
publisher
Unit of Diabetes and Celiac disease, Clinical Sciences, Malmö.
defense location
Jubileumsaulan
defense date
2011-06-03 09:00
ISSN
1652-8220
ISBN
978-91-86871-06-2
language
English
LU publication?
yes
id
d4a1c4f6-1cd2-4f44-852c-f669ccd0dfeb (old id 1940524)
date added to LUP
2011-06-14 13:21:29
date last changed
2016-09-19 08:44:49
@phdthesis{d4a1c4f6-1cd2-4f44-852c-f669ccd0dfeb,
  abstract     = {Objective<br/><br>
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. <br/><br>
Study population and Methods <br/><br>
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. <br/><br>
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.<br/><br>
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. <br/><br>
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). <br/><br>
<br/><br>
Study I-IV<br/><br>
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&lt;0.0001), IA-2A (p&lt;0.0001) and IAA (p&lt;0.0001). Seroconversion during pregnancy was observed for GADA in 10 (8%), IA-2A in 3 (16%) and IAA in 37 (35%) mothers.<br/><br>
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. <br/><br>
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&lt;0.0001). <br/><br>
Study IV: Gestational EV infections have been associated with risk HLA-DR as well as with type 1 diabetes in the child. We analyzed enterovirus RNA (EV-RNA) and IgM (EV-IgM) in relation to type 1 diabetes HLA-DQ risk genotypes and to islet autoantibodies in non-diabetic mothers studied both in early pregnancy and at delivery. EV-IgM, but not EV-RNA was detected during early pregnancy in 12% (44/365) islet autoantibody positive mothers compared to 11% (156/1457) of the controls (p=n.s.). In early pregnancy, mothers with HLA-DQ 2/2 or 2/X genotypes showed, in adjusted logistic regression, an increased risk for islet autoantibodies (OR 1.85, 95% CI 1.34-2.54; p=0.001). EV-IgM was not associated with HLA-DQ in early pregnancy. However, after adjusting for parity, maternal age, year of birth and season of early pregnancy, early pregnancy EV-IgM combined with DQ2/2 or 2/X increased the risk for the mother to be positive for islet autoantibodies at delivery (OR 3.10, 95% CI 1.35-7.15; p=0.008). <br/><br>
Conclusion<br/><br>
From these studies we conclude that pregnant non-diabetic mothers with islet autoantibodies at delivery had significantly higher titers of autoantibodies during early pregnancy than at delivery. As the statistical power in the seroconverting mothers was insufficient, further studies are needed to determine if the risk for type 1 diabetes in the offspring differs between mothers who already had increased titers of islet autoantibodies during early pregnancy or acquired them during pregnancy. Moreover, we conclude that a shift in the Th1/Th2 mediated cytokine pattern during early pregnancy, possibly caused by viral infection may be associated with CD in the offspring. Furthermore, the results from study III suggest that increased levels of IFN-γ and possibly IL-2 during early pregnancy was associated with an increased risk for multiple, persistent islet autoantibodies, type 1 diabetes, or both, before seven years of age in the offspring. Our final study concludes that EV-IgM in early pregnancy increased the risk for islet autoantibodies at delivery in non-diabetic mothers who carry HLA-DQ 2/2 or 2/X type 1 diabetes risk genotypes.},
  author       = {Lindehammer, Sabina},
  isbn         = {978-91-86871-06-2},
  issn         = {1652-8220},
  keyword      = {Islet autoantibodies,pregnancy,type 1 diabetes,celiac disease},
  language     = {eng},
  pages        = {162},
  publisher    = {Unit of Diabetes and Celiac disease, Clinical Sciences, Malmö.},
  school       = {Lund University},
  series       = {Lund University Faculty of Medicine Doctoral Dissertation Series},
  title        = {Triggers of autoimmunity. Studies on gestational events.},
  volume       = {2011:57},
  year         = {2011},
}