Mucosal Immunity and the Microbiome

The intestinal tract is one of the most complex organs of the human body. It is inhabited by trillions of microbes throughout the width and length of the gastrointestinal tract. It also harbors 80 percent of the immune system, which stands watch along the body’s main interface with the outside world. The microbiome and the resident immune cells are separated by the lining of the gut, a diverse and dynamic tissue composed of intestinal epithelial cells (IEC).

IECs not only constitute the first barrier in the gut against the lumen, they are also engaged in constant crosstalk between the gut lumen and immune cells. Since this intersection is central to our health and wellbeing, it is important to gain a clearer picture how IECs, immune cells and the microbiome interact with each other.

Earlier findings indicated that a surface molecule expressed by IECs, which is known as herpes virus entry mediator (HVEM), plays a central role in the signaling network connecting the microbiome with the gut immune system. Dr. Gooyoung Seo wants to explore the mechanistic bases for the effects of HVEM on immune and microbial homeostasis in the intestine, and the connection, if any, between decreased IEL populations and the altered microbiota. To do so, she will conduct an in depth analysis of gene expression in the presence and absence of HVEM to identify relevant downstream targets of HVEM activity. In collaboration with La Jolla Institute’s Imaging Core, Dr. Seo also developed a sophisticated method for carrying out intravital microscopy in the intestine to learn whether there is a connection between the observed decrease in IEL and increase in certain members of the microbiome is directly linked to HVEM.

Dr. Seo hopes that her study will provide a deeper understanding the function of the mucosal immune system in providing protection while avoiding destructive intestinal inflammation.