Pathogenic invaders
Dissecting the interplay between good and bad gut bacteria to advance human health
An arms race is underway in the gut microbiome between commensal microbiota and invasive bacterial pathogens as UT Southwestern researcher Dr. Vanessa Sperandio watches the action on the front lines.
Dr. Sperandio is a Professor of Microbiology and Biochemistry whose latest research focuses on whether a plant-based diet is better for intestinal health than a typical Western diet, which is higher in fat and protein but relatively low in fruits and vegetables.
In one of her studies, mice fed a plant-rich diet were less susceptible to gastrointestinal infection from enterohaemorrhagic Escherichia coli, or EHEC, a pathogen linked to severe foodborne disease outbreaks each year. These E. coli infect the large intestine and produce a toxin that causes serious complications and death in some cases.
Dr. Sperandio’s study on a mouse model of EHEC was published in Nature Microbiology in December.
“My laboratory studies which chemicals these pathogenic bacteria monitor inside the human intestine to activate their virulence and the weapons they use to make you sick,” Dr. Sperandio says. “I like knowing how things work independently and how they work as a team; that’s what drives me.”
Microbial world puzzles
She is a solution seeker – and the microbial world offers a jigsaw puzzle with billions of pieces to assemble.
The research conducted in the Sperandio laboratory aims to understand how the so-called good, or commensal, bacteria work with their host to disarm intestinal pathogens without disrupting the gut. Her Nature Microbiology study found that pectin, a gel-like substance found in the fiber of many fruits and vegetables, packs a powerful, immune-boosting punch against pathogenic bacteria. Once pectin is digested by the gut microbiota of a mouse, it is turned into a sugar acid called galacturonic acid, which inhibits EHEC’s ability to cause disease, she says.
“I like knowing how things work independently and how they work as a team; that’s what drives me.”
— Dr. Vanessa Sperandio
“Our study finds, first, that the good E. coli and the pathogenic ones like EHEC use different sugars as nutrients,” she says, adding that the two types of E. coli may have evolved to avoid competing for the same energy sources. “Second, we find that dietary pectin protects against the pathway pathogenic EHEC use to become more virulent.”
Dr. Sperandio says that this research is one step in a journey to define the molecular mechanisms that govern how commensal species in the gut impact the virulence of intestinal pathogens.
“The metabolic repertoire of most microbes is extremely rich,” she says. “Even bacteria within the same species have different metabolic traits and different ways they go about adapting their metabolism to thrive. If we understand how commensal microbes try to win the arms race with the host against pathogenic microbes, then we can begin to develop smarter strategies to combat disease.”
Written in the stars
Dr. Sperandio has pursued many interests throughout her life, including oil painting and classical ballet, but she fostered a love for science at a young age.
“I initially thought I was going to become an astronomer,” she says. “But during my first year in high school, I had a fantastic biology teacher, and after the first class, which was a lesson on the beginning of life and evolution, I fell in love with the subject and decided that was the path I wanted to follow.”
Dr. Sperandio grew up in Londrina, which roughly translates to “little London.” It is one of the largest cities in the southern Brazil state of Paraná. She received her doctorate in molecular biology from the State University of Campinas in Brazil and finished postdoctoral training in 2001 at the University of Maryland School of Medicine. At the time, she planned to stay in Baltimore with her husband; however, she met two UT Southwestern faculty members at a conference who encouraged her to apply for a position here.
“During the interview process, I just had a feeling that I belonged here. The stars aligned, and I ended up coming to Dallas.”
Finding strength in differences
UT Southwestern's Department of Microbiology is small, but its investigators produce impressive work.
“The Department publishes really well and has a big footprint nationally considering its small size,” Dr. Sperandio says. “We hire carefully and on the basis that an investigator should be both an expert and a team player; a scientist who asks interesting biological questions and will not just go with what is in vogue.”
The members of the close-knit Department say diversity of thought and collaboration make up the foundation of their success, and their environment reflects that mindset. The laboratories are designed to be a blend of connected and unconnected open spaces that are well suited for multidisciplinary teams.
“I am a citizen of the world and to me it is all part of the adventure.”
— Dr. Vanessa Sperandio
“It's an open corridor, but there are support rooms for equipment in between the different investigators,” Dr. Sperandio says. “It is very collegial. We share everything.”
When asked if she encountered any culture shock when she began working in U.S. laboratories, her answer was firmly rooted in a respect for others. She highlighted the value of multiple perspectives and the thread of similarities all humans share.
“I think there are two types of people: Those who are citizens of the world and those who are not,” she says. “The former are willing to learn about new cultures and can see that every culture has something to offer, whereas the latter have a harder time adapting. I am a citizen of the world and to me it is all part of the adventure.”