Doctoral defence: Kertu Liis Krigul “The gut microbiome at the interface of human health and disease”

On 4 October at 13.15 Kertu Liis Krigul will defend her doctoral thesis “The gut microbiome at the interface of human health and disease” for obtaining the degree of Doctor of Gene Technology.

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Supervisors:
professor Elin Org, University of Tartu
associate professor Tõnis Org, University of Tartu

Opponent:
Nassos Typas, European Molecular Biology Laboratory (Germany)

Summary:
Undoubtedly, an increasing number of publications, continuous public interest, numerous clinical studies, and clinically accepted microbiome-based treatments have shown great potential in the microbiome field for improving our health. However, we are still mostly in the exploratory phase, trying to understand general patterns and changes in how and which of our lifestyle choices impact the microbiome and how the microbiome can affect our physiology. We still need to characterise factors in greater detail to understand what drives the differences between individuals. Additionally, we are trying to determine possibilities and caveats on whether using the microbiome could be helpful in improving disease diagnostics and predictive tools. The current thesis tried to tackle some of these questions.

Firstly, we discovered that samples used in national colon cancer screening programs could be used to study the microbiome, which might simplify population-wide sample collections and microbiome-test-supplemented screening programs in the future. Secondly, the population cohorts, supplemented with Electronic Health Records, such as the Estonian Microbiome cohort in Estonian Biobank introduced in this thesis, are valuable for uncovering new factors influencing the microbiome. As an example, we discovered that the 10-year repeated usage of antibiotics or antidepressants is significantly associated with the changes in the gut microbiome, irrespective of recent usage. Furthermore, using human-to-mouse microbiota transplantation, we showed that a human repeated history of antibiotic use results in mucosal barrier defects in the colon of mice, even though the donors had not used antibiotics in the last 6 months.

Although there is still a lot to discover and the field is still figuring out its standards, all these studies presented in this thesis indicate the important role of the gut microbiome in the interface of human health and disease. We are already increasingly understanding the long-term effects of antibiotics and other drugs on the microbiome and our health. Studies presented in this thesis, in combination with research done by others, warrant us to follow the principle of “as much as needed, as least as possible” in medication usage, as the long-term effects need further studies.

The defence can be followed in Zoom (Meeting ID: 964 4776 6943, Passcode: 262453).