BBC: Nobel Medicine Laureate outlines future treatments he hopes will be inspired by work

Shimon Sakaguchi, together with American researchers Mary Brunkow and Fred Ramsdell, has been jointly awarded the 2025 Nobel Prize in Physiology/Medicine for their groundbreaking work on regulatory T-cells, or T-regs — a unique class of immune cells that prevent the body’s defence system from turning against itself.

In an exclusive interview with The Conversation, the Japanese immunologist discussed the transformative medical possibilities that could stem from their discovery.

Sakaguchi recalled being inspired by an experiment involving newborn mice conducted by his colleagues at the Aichi Cancer Center Research Institute in Nagoya. The researchers had removed the thymus from mice three days after birth. It was already known that the thymus plays a crucial role in developing immune self-tolerance — the process by which T-cells, a type of lymphocyte or white blood cell that could potentially attack the body, are identified and destroyed. What happened next caught Sakaguchi’s attention.

Sakaguchi explained that if the thymus is removed from a normal newborn mouse, the expected outcome would be an immune deficiency because lymphocytes are absent:

"But what happened is just the opposite: they developed autoimmune diseases.  This disease is very similar to what we see in humans … but of course, human patients are not removed of the thymus, so there must be a common mechanism, which can explain spontaneous autoimmune diseases in humans," he stated in the interview.

Seeking to understand this phenomenon, Sakaguchi conducted a new experiment to prevent the mice’s immune systems from spiralling out of control. When he transferred T-cells from genetically identical healthy mice into those without a thymus, he discovered that autoimmune disease could be prevented.

“This suggests that there must be a T-cell population which can prevent disease development,” he said.

Expanding the areas of application

Sakaguchi’s early research focused on the origins of autoimmune diseases. “But in the course of my research, we have gradually understood that T-regs are more important,” he says. These cells have since been linked not only to autoimmune disorders but also to cancer progression and organ transplant tolerance.

Today, Sakaguchi is exploring innovative ways to harness T-regs for medical treatments, including methods to convert other types of T-cells into T-regs to combat specific autoimmune conditions.

His near-term goal is to see clinical trials in cancer immunotherapy progress toward real-world treatments. Yet, his curiosity extends further — into how T-regs could help fight inflammation-related diseases and even repair damaged tissue.

"Neuro-degenerative diseases such as Alzheimer’s disease or Parkinson’s disease, all involve inflammation. By just targeting that kind of inflammation, we maybe [could] stop the disease progression, or delay the disease progression. We hope that it is very true and then it really works for such diseases," the immunologist explained.

By Nazrin Sadigova