There is increasing evidence that the composition of the gut microbiota is important for health and disease. New research shows that gene variants in eleven areas of the human genome affect which bacteria are present in the gut and the functions they have there. So far, only two of these eleven areas have been known. The study, published in the journal Nature Genetics, has been led by Tove Fall at Uppsala University. Marju Orho-Melander, who leads a research group in genetic epidemiology at Lund University, is one of the senior co-authors of the article.
“We have succeeded in identifying several new genetic regions that are important for the gut flora. By studying the importance of genes for the gut microbiota, we gain new knowledge about biological mechanisms that regulate the gut microbiota and how the risk of developing various diseases is affected. This is a big step forward for the research area,” says Marju Orho-Melander, professor of genetic epidemiology at Lund University Diabetes Centre.
Mapping at the individual level
The researchers have analysed genetic data and gut bacteria from over 16,000 individuals from Sweden and carefully mapped which bacteria the participant have in their intestines. Marju Orho-Melander's research group at Lund University has been responsible for the collection and analysis of samples from around 6,000 participants in the population study SCAPIS in Malmö and the Malmö Offspring Study (MOS).
“It is important to study the gut microbiota composition of each individual because there can be an extreme variation. Some individuals may have 20 bacterial species while others have 1,000 bacterial species in the gut. In general, it is beneficial to have as many species as possible. Previous research has, for example, shown that several different diseases are associated with fewer bacterial species in the gut microbiota and that many common drugs can reduce the richness of species,” says Marju Orho-Melander.
In this study, the researchers have succeeded in identifying a gene variant that can be linked to the richness of species in the gut microbiota. The findings from the Swedish cohorts have been confirmed in the HUNT study in Norway.
The risk of developing diseases
The researchers have also discovered associations between some of the gene variants and several diseases. Some of the gene variants were linked to the risk of celiac disease, haemorrhoids, and cardiovascular disease. This part of the study included 12,652 individuals from the HUNT study in Norway and was led by researchers at the University of Gothenburg and the Norwegian University of Science and Technology. The findings from this study have been replicated in Swedish population studies. Marju Orho-Melander is one of the co-authors of the article, which is also published in Nature Genetics.
“If we conduct larger studies with more participants, we can find additional genetic regions that are important for the gut microbiota and learn more about mechanisms that link the gut microbiota to various diseases, such as diabetes. In this study, we found no link between the gene variants we studied and the risk of diabetes,” says Marju Orho-Melander.
Marju Orho-Melander and Tove Fall are collaborating on several studies which explore the importance of the gut microbiota for human health. Tove Fall at Uppsala University hopes that knowledge about the gut microbiome can have an impact on how we prevent and treat diseases.
“Given that many aspects of our health are linked to the gut microbiome, we naturally want our research to contribute to better ways of preventing and treating diseases by paying attention to the interaction between genes, gut biology and the microbiome,” says Tove Fall, professor of molecular epidemiology at Uppsala University and responsible for one of the studies.
Link to the press release about the articles in Nature Genetics on Uppsala University’s website
