From north woods naturalist to immunology investigator: the making of a medical scientist
As a kid growing up in Michigan’s Upper Peninsula, in a town known as the state’s Moose Capital, Dan Peltier was always poking around the woods and lakeshores, picking up Petoskey stones or gathering bugs and plants for school collections. Hiking, hunting and camping, of course, were also high on his list of favorite activities, but on most excursions he ended up spending more time investigating biological curiosities than doing whatever he’d originally set out to do.
That same desire to explore unknown territory and “see something no one else has ever seen” still motivates Peltier, whose quests now take him not to the woods, but deep into the immune system.
As a student in the Medical Scientist Training Program, concurrently earning an M.D. degree and a Ph.D. in Microbiology & Immunology, Peltier is interested in the interplay between illness and immunity.
“There’s one common theme you learn when you start studying medicine: As a doctor, you really don’t ever heal anyone; you sort of nudge them in the right direction, and the body heals itself,” Peltier says. “What’s central to that idea is the role of the immune system, so that’s why I wanted to study the interface between disease and immunology.” That particular area of study and the program in which he is enrolled allow Peltier to combine his fascination with basic research with his equally strong desire to help “nudge” sick people in the direction of health.
During his undergraduate years, Peltier volunteered at a hospital and worked in a university laboratory doing research into how tumors form. “I discovered that I liked both the medical and research sides and didn’t want to give either up, so I decided to pursue both,” he says.
Now working in the lab of David J. Miller, M.D., Ph.D., Peltier is investigating how nerve cells (neurons) detect and respond to viruses that infect them in diseases such as western equine encephalitis, a mosquito borne disease that produces brain inflammation and can lead to coma or death. The western equine encephalitis virus (WEEV) homes in on neurons in the central nervous system, virtually ignoring other types of cells. And while it’s equally adroit at invading both mature and immature neurons, it causes more severe infections in the immature ones.
One possible explanation is that mature neurons are better at detecting and defending against infection, says Peltier, and his research suggests that’s exactly what’s happening.
“What I look at is the recognition of infection,” he says. “When a cell gets infected with WEEV, the virus replicates and produces things that the cell doesn’t normally make. There are sensors within the cell that detect this and then signal for the production of a protein that has antiviral properties but also acts as a warning signal to activate the rest of the immune system.”
Peltier is focusing on what happens between the time the cell recognizes it is infected and the time it starts churning out the antiviral/warning protein. “That part of the pathway, I’m finding, is more sensitive in mature neurons. They have a greater ability to detect that they’re infected and then make the antiviral protein.”
Such a detail may seem esoteric, but it’s exactly the kind of information a medical scientist needs to design treatments that tip the balance toward health. Anything Peltier learns will be useful not only for understanding how to deal with disease-causing viruses like WEEV, but possibly also for combating diseases such as Alzheimer’s, Parkinson’s and ALS, which may result from overactive immune responses on the part of mature neurons.
Whatever diseases Peltier probes and wherever his insights lead, you can bet he’ll be venturing forth with all the enthusiasm of his boyhood explorations.
“There’s nothing like seeing something no one else has seen and then being the first to try to interpret it,” he says. “In this kind of career, you get to live that experience over and over again.”
