Type 1 diabetes study provides new details on development of children’s gut microbiome

Researchers investigating possible causes of type 1 diabetes have published new details about how environmental factors such as breastfeeding affect the microbes in the gut (i.e. the gut “microbiome”) as children age. The Environmental Determinants of Diabetes in the Young (TEDDY) is an international study investigating what environmental factors might trigger or protect against type 1 diabetes. TEDDY is following almost 6,000 children at high genetic risk of developing type 1 diabetes from their birth through age 15. One factor of interest to TEDDY researchers is the gut microbiome. Previous studies suggested that crosstalk between the immune system and gut microbes in infancy and childhood can be linked to immune-related diseases later in life, such as the autoimmune attack on pancreatic beta cells that occurs during type 1 diabetes. TEDDY scientists are interested in whether or not changes in the gut microbiome affect a child’s risk for developing type 1 diabetes. To investigate this, they analyzed donated stool samples from hundreds of girls and boys participating in TEDDY, identifying the bacteria in the children’s gut microbiomes and tracking how the types and abundance of these bacteria changed as the children grew. Information on the children’s health, diet, geographical location, and other environmental exposures was then used to explore whether these factors may have affected the gut microbiome and how those effects correlated with the children’s type 1 diabetes status.

From this research, one of the largest-ever clinical microbiome studies in infants and children, TEDDY scientists identified three distinct phases of gut microbiome development: a developmental phase (3-14 months of age), a transitional phase (15-30 months of age) where the microbiome diversifies, and a stable phase (31-46 months of age) where the microbiome’s composition is largely established. Within these phases, researchers found considerable personal variability between gut microbiomes. Breastfeeding was the most important factor associated with how the gut microbiome developed in the first years of life. For example, the microbiome of infants not receiving breastmilk moved more quickly through the developmental phases compared to children receiving any amount of breastmilk, even if supplemented with formula or solid foods. Some of the other factors that affected the gut microbiome included probiotic and antibiotic use, geographical location, and having siblings and/or furry pets. Finally, researchers found a possible beneficial effect on risk for type 1 diabetes from bacteria that produce short-chain fatty acid molecules. These molecules are often made during fermentation of indigestible carbohydrates like fiber, and future research will be needed to determine whether these molecules or the bacteria that produce them protect against type 1 diabetes.

The TEDDY cohort is largely White and non-Hispanic, so further work will be needed to determine if these discoveries are applicable to all children. However, these new findings could help inform the development of strategies or therapies to support the development of a healthy gut microbiome in children. They also demonstrate how the ambitious TEDDY study is already expanding our knowledge of child development and the human microbiome, while continuing its search for causative and protective factors for type 1 diabetes.