Doctoral defence: Kärt Simre "Development of coeliac disease in two populations with different environmental backgrounds"

On 22 August at 14:00 Kärt Simre will defend her doctoral thesis "Development of coeliac disease in two populations with different environmental backgrounds" for obtaining the degree of Doctor of Philosophy (in Medicine).

Supervisors:
Professor Raivo Uibo, University of Tartu
Associate Professor Oivi Uibo, University of Tartu
Professor Vallo Tillmann, University of Tartu

Opponent:
Marko Kalliomäki, University of Turku (Finland)

Summary
Coeliac disease (CD) is a dietary gluten and gluten-related prolamines induced immune-mediated systemic disorder that occurs in genetically predisposed people. “Gluten” is a general term for alcohol-soluble proteins present in various cereals (wheat, barley and rye). In recent decades the prevalence of CD has increased worldwide and there can be marked differences between countries. It is known that most people with the genetic risk for CD and exposure to gluten do not develop CD, so different environmental factors must be involved. The general aim of the present thesis was to clarify the development of CD in two paediatric populations with different socio-economic backgrounds, Estonia and Finland, and to find out the role of different risk factors in this process. Paying special attention to early feeding and infections. In addition, to characterize the microbiota composition of the breast milk and its possible relationship with immunological markers. 

The study is based on the data and biomaterials collected during the international prospective observational DIABIMMUNE Study, which set out to assess the role of the hygiene hypothesis in the development of type 1 diabetes and other immune-mediated diseases. The study included two cohorts: a birth cohort (BC) observed from birth up to the age of 3 years and a cohort of young children (YCC) examined for the first time at the age of 3 years and followed up to the age of 5 years. During the study period 29 children developed CD: eight Estonian and 21 Finnish children. The control children were selected from the BC or YCC of the DIABIMMUNE Study. For breast milk sample analyses, six children of the BC were selected. 18 control children were selected from the BC. 

We found that there is a significant difference in the 5-year cumulative incidence of childhood CD between Estonia and Finland, which is higher in the latter country (0.27% vs 0.77%). The children from Finland tended to develop IgA-tTG antibodies earlier than the children from Estonia. No difference was seen in the age at cereal introduction or in the duration of breastfeeding between the children with CD and the control children. Sequential infections early in life may increase the risk for developing CD. The breast milk microbiota of the mothers of children who developed CD differed in terms of higher bacterial phylotype abundance and diversity, as well as in relation to bacterial composition when compared to the mothers of the unaffected children.