Diversity is critical for the health of our gut, but also in science, Dr. Carolina Tropini says
Dr. Carolina Tropini had never intended to study bacteria before she started her PHD; in fact, not studying bacteria was her only requirement.
Like most people, she saw bacteria as dirty, infectious agents that only carry pathogens. That all changed when she heard a Stanford University professor talk passionately about gut microbes and their role in human health. A few projects in, she realized the misconception and started seeing the beauty of microbes, not only in our own health, but in the health of the planet as well.
“I realized the mistake that I made and I have never turned back once I started working on bacteria,” she says. “It’s such a deep and expansive world of things that we don’t know yet and they’re so important for human health and the health of the planet. It’s been an incredible chance to learn so much and work on things that are not only intellectually stimulating, but also very impactful.”
Tropini is this year’s winner of the Johnson & Johnson Women in STEM2D Scholars Award in the field of Engineering — one of six selected from more than 500 nominees worldwide. The award will provide her with three years of mentorship and $150,000 in funding. She is the first Canadian to win this award.
Understanding inflammatory bowel disease
Her research looks at how the gut changes in inflammatory bowel disease (IBD). There is still no known cure for IBD. Her team has found that individuals who have IBD have microbiota that looks significantly different from someone without. They’re trying to find the specific bacteria that can ameliorate the inflammatory environment in the gut.
“The example I use is, if the IBD gut is like a desert and you’re trying to make it like a forest, the first thing you need to do is modify the environment so it can accept the forest,” she says. “In a desert, you’d have to water things and get rid of the sand. Specific species that are better adapted to the desert get introduced first and these make way for the more complex communities one would like to foster. We’d like to take a similar approach, but instead of plants, of course, we’re thinking about bacteria and microbial species and how we can introduce them and modify the environment so it’s more permissive for the good species we want to keep in there.”
The recorded history of bacteria dates back to the 1700s, when microscope pioneer Antoni van Leeuwenhoek first scraped out the plaque in his teeth (as well as some of his own stool during a bout of diarrhea) and looked at it under a microscope. He noticed moving things that he would call “animalcules.” They were bacteria — he just didn’t know it yet.
Bacteria and viruses have had a negative connotation since then, up until the past two decades when researchers started realizing why we have so much bacteria in our bodies — we carry around somewhere in the neighbourhood of tens of trillions of organisms every day.
“We need them,” Tropini says. “They digest food that we’re not able to digest. They produce vitamins that we’re not able to produce, they protect us from pathogens and we’ve evolved with these communities and we really need them to be healthy. One of the things I find most beautiful is how much of human biology is tied to these organism, and we don’t even realize it.”
Tropini gives the example of childbirth. As soon as the baby is born, the mother coats her vagina with bacteria that will help the baby consume milk, and during the process of birth, the baby is seeded with bacteria from the mother’s body at the vagina.
“The body of the baby gets inoculated with this bacteria, and these are the first bacteria and microbiota that the body sees,” she says. “From that point on, the entire digestive tract of the baby gets set up to host these microorganisms. It’s really beautiful if you look at maternal milk, about a quarter of it is made up of things the baby cannot actually break down. There are sugars that only microbes are able to consume. It happens even for mothers who are malnourished, it highlights how important they are for our own functioning.”
Diversity is important — in nature, our microbiota, and science
Our modern lives have become optimized for fighting pathogens, but it’s also led to a loss in diversity in our microbiota. Between the heavy use of antibiotics, strong sanitization of our surroundings, and spending less time outdoors, we’re no longer exposed to as many bacteria as our ancestors.
“While this helps decrease the burden of infectious diseases, it’s correlated with a very large increase in inflammatory diseases,” Tropini says. “Our bodies are primed to be exposed to bacteria and viruses and microbes. Now all of a sudden, we’re not doing this anymore. There’s a mismatch between the bacteria that our body expects and the ones that we actually have.”
Our diet also has led to this loss of diversity. Our ancestors used to have high amounts of digestible fibre in their diets, but now that we eat more processed foods, we don’t see nearly as many bacteria.
Whether you become vegetarian or decide to change the way you eat overnight, microbiota are extremely malleable and able to duplicate and replicate rapidly — “in the order of tens of minutes to hours,” she says.
However, our biology does not adapt that quickly. Our microbiota can change overnight, but our biology has remained relatively identical to that of our ancestors from the last few centuries.
“We have a microbiota adapted for foods that are very highly processed and a lifestyle that is different than what our biology got set up with,” she says. “We think this mismatch basically is what is leading to a lot of the inflammatory diseases, which has an effect on diseases like allergies, obesity, diabetes — all of which our ancestors did not know existed.”
Tropini has looked at populations that have not experienced the level of industrialization, antibiotics, and processed foods North Americans have seen. One group they’ve looked at is the Hadza population, the modern hunter-gatherer people in Tanzania’s Serengeti. Tropini says they have a much higher diversity of bacteria and diets completely different from the ones we have. While they may have more infectious diseases, they do not suffer at all from inflammatory diseases.
“It’s almost like an ecosystem; if the niches are very diverse and highly occupied, it’s much harder for a new invader to be able to take place and start utilizing the food that because there’s very little food available. If the microbiota is well-fed and very diverse, it’s much harder for pathogens to be able to implant because they’re selected out.”
Tropini says these complex problems require many vastly different perspectives to combat them.
“This ties back into how we need to increase diversity right now in science, and I feel this really deeply,” she says. “We see these analogies with the microbiota. A more diverse community is not only the right thing to do, it’s better.”
As a first-generation university graduate, Tropini knows firsthand the importance of reaching out to under-represented communities, especially in allowing Indigenous, people of colour, and women to feel empowered and supported as academics. Her lab works with Indigenous communities to provide students with internships.
“We need to have involvement before they get to university, we need to let them know that these are things that are achievable,” she says. “My parents are not academics, but they had the foresight to expose my sister and I to a lot of science and to mentors who helped us realize what we are excited about. Sometimes, if that link is missing, you wouldn’t know what you’re missing.”
It’s this valuable mentorship that can help push careers further.
“If you find people who will champion you and mentor you, that’s the best thing you can find,” she says. “Someone who is supportive, but also critical, will help you become the best scientist you can be.”
Tropini is also passionate about the involvement of people from different backgrounds in science.
“There are different things that are obvious to you, that are not obvious to other people, and having this discourse is just so important. In our lab, we have the goal of having a community that is welcoming and open and allows for people to to be heard and to be successful and I think that’s one of the things that I’m excited about it.”
We see these analogies with the microbiota. A more diverse community is not only the right thing to do, it’s better.
This article by Diana Duong originally appeared in the Vancouver Sun September 19, 2020