Dr. Lora Hooper

Could the gut’s bacteria – known to affect both sickness and health – also make us fat?

Dr. Lora Hooper, Chair of Immunology at UT Southwestern, addressed this question at the fall President’s Lecture Series presentation, where she discussed how the trillions of bacteria that line the intestines affect metabolism.

“I think that the average person may be unaware of the extent to which the gut microbiome shapes our metabolism,” said Dr. Hooper, who is also a Howard Hughes Medical Institute Investigator. “The hundreds of bacterial species that make up an individual’s gut microbiome have a big say in how readily body fat is accumulated – at least in mice.”

In her talk, titled “Gut Reactions: Exploring How the Microbiome Contributes to Health and Disease,” Dr. Hooper shared her latest research on this subject. The event took place Sept. 28 in the Tom and Lula Gooch Auditorium on South Campus, with a reception immediately following.

The fundamental elements of Dr. Hooper’s work can be traced back to Dr. Louis Pasteur, who founded the field of microbiology and famously predicted the existence of beneficial resident microorganisms. In 1885, he further hypothesized that a germ-free colony of lab animals – animals protected from exposure to any bacteria – would be an excellent way to study the effects of so-called good, or commensal, bacteria. The word commensal comes from two Latin roots that translate to “sharing a table,” which is just what the estimated 100 trillion commensal bacteria that line the human intestines do in symbiotic relationships with their hosts. Under normal conditions, the commensal bacteria survive with plenty of nutrients in exchange for helping their hosts break down food so that more energy can be extracted from each bite.

Dr. Hooper, also Director of the Walter M. and Helen D. Bader Center for Research on Arthritis and Autoimmune Diseases and a Professor of Immunology in the Center for the Genetics of Host Defense, has raised and studied a colony of germ-free mice at UT Southwestern for several years now. Her investigations have yielded many unique discoveries, including:

• Host cells near the “demilitarized zone” of the intestinal borderlands – a tiny 50-micron-thick mucosal layer that lines the inner wall of the intestines – create a protein antibiotic that serves as a peacekeeper. In a healthy gut, that protein antibiotic blocks commensal bacteria from breaching the intestinal walls, rendering them unable to cause infection elsewhere in the body.
• The production of a key immune cell in mice is controlled by the body’s circadian (24-hour) clock.

“Virtually every life form on Earth undergoes physiological changes on a 24-hour cycle in response to changes in light,” Dr. Hooper said. “We knew that eating and sleeping vary dramatically between day and night, but little was known about the clock’s effect on the immune system.”

Dr. Hooper’s presentation focused on key findings since her 2013 report in Science on the immunity-body clock link – including how the clock and the microbiome work together to regulate metabolic pathways that could affect the processing of dietary fat and fat deposits in the body.

Dr. Hooper, a graduate of Rhodes College in Tennessee, earned her doctorate at Washington University in St. Louis. Her many honors include election to membership in the National Academy of Sciences in 2015. A faculty member at UT Southwestern since 2003, Dr. Hooper became Chair of the Department of Immunology in 2016.

Dr. Hooper holds the Jonathan W. Uhr, M.D. Distinguished Chair in Immunology, and is a Nancy Cain and Jeffrey A. Marcus Scholar in Medical Research, in Honor of Dr. Bill S. Vowell.