Various immune cells in the gut recognize and respond to microbes that live there, which are collectively known as the gut microbiota. This project focuses on a subset of immune cells termed B cells, which are important for functions such as antibody production. In particular, we are investigating how certain kinds of beneficial gut bacteria interact with B cells to improve gut health. Moreover, we are testing whether harmful bacteria found in the gut of patients with Inflammatory Bowel Disease do not interact with B cells, which may partly explain the altered immune responses observed during gut inflammation in these patients. Collectively, our work will have a significant impact on Inflammatory Bowel Disease by identifying and investigating new ways by which beneficial and harmful bacteria interact with B cells in the gut, which could have important implications for the future treatment of these diseases.