Grant: CIHR Fellowship

The human gut microbiome is a community of trillions of tiny organisms, such as bacteria, that live in our gut. Amazingly, it is estimated that there are as many bacterial cells in our gut microbiome as human cells in our body. The different types and amounts of gut bacteria are normally maintained in a healthy balance. This balance supports our overall health, but the disruption of this balance is linked to severe diseases such as heart disease and cancer. How a healthy gut microbiome is normally maintained, and how it becomes imbalanced, is not well understood. Given the importance of the gut microbiome to our health, we believe that the body actively works to prevent such imbalances. We propose that neutrophils, a type of immune cell known for fighting infections and killing bacteria, play a crucial role in maintaining a healthy gut microbiome by continuously entering the gut and removing unwanted bacteria. Using an advanced microscopic imaging technique called intravital microscopy, we will directly observe the behaviour of neutrophils in the intestines of living mice and examine whether neutrophils are recruited to the intestine and interact with gut bacteria. We will also test if mice raised completely germ-free, or mice treated with antibiotics to eliminate gut bacteria, have altered levels of neutrophils in the gut. Finally, we will test if experimentally removing neutrophils causes the gut bacteria to fall out of a healthy balance. Understanding how our gut microbiomes are regulated is important to identifying what disrupts a healthy balance, and to develop ways to prevent or treat it. This research will explore the role of neutrophils in maintaining a healthy gut microbiome and may lead to new treatments for diseases from heart disease to cancer.