About the PhD thesis

Inflammatory Bowel Diseases (IBD) are chronic diseases of the gastrointestinal tract with Crohn’s Disease (CD) and Ulcerative Colitis (UC) being the two main IBD types. Up to 50% of patients with IBD experience IBD-related inflammatory conditions outside of the gastrointestinal tract, termed extraintestinal manifestations (EIM). Some of these include manifestations of the joints, eyes, skin and liver.

EIMs impact quality of life and can lead to serious complications such as vision loss, disability, and liver failure. The pathogenesis of EIMs remains unknown, however gut microbiota disturbances are a well-known feature of patients with IBD.

This thesis aimed to investigate gut microbiota composition and function in patients with IBD with or without EIMs.
This was achieved through bacteria and fungi community analysis of fecal samples using marker gene sequencing and metagenomic sequencing together with metabolomic analysis of fecal samples. These datasets were compared with clinical data and disease markers measured in fecal and blood samples.

156 patients with IBD were enrolled in the thesis studies. Major findings included identification of significant microbiota and metabolite differences observed in patients with EIMs compared to without.

The studies have demonstrated that gut microbiota differences exist in patients with EIMs compared to without, emphasizing the need for further research to understand why these gut microbiota differences occur and whether or not they are involved in the development of EIMs.