Scientists at McGill University have discovered that tissue-resident memory T cells can detect the mechanical stiffness of their surrounding environment, challenging the long-held assumption that chemical signals exclusively govern immune memory development. Published in Nature Immunology, the study reveals that physical forces actively shape how these protective cells survive long-term.
Engineering Tissue Stiffness in Collagen Gels
For years, researchers believed that tissue-resident memory T cells were guided mainly by chemical signals. That paradigm is shifting.
To investigate how physical surroundings alter immune behavior, researchers gathered immune cells from both humans and mice. They embedded these cells inside specially designed collagen gels engineered to replicate varying levels of tissue stiffness. As the stiffness of the gel increased, the T cells were increasingly likely to acquire characteristics associated with tissue-resident memory cells.
These specialized immune cells remain stationed in tissues long after an initial infection clears. They respond quickly if the same threat returns. Adapting to the stronger mechanical forces within tissues appears to be important for these protective cells to survive over time.
“This is an exciting fundamental finding that challenges the way we think about immune cells,” said Judith Mandl, lead author and professor in McGill’s Department of Physiology. “It suggests T cells can ‘feel’ their surroundings and adapt to them, making the physical environment an active force in shaping their behavior.”
Implications for Tumors and Autoimmunity
The discovery extends far beyond fundamental cellular mechanics. Solid tumors are often dense and physically difficult for immune cells to penetrate. Understanding how mechanical cues govern lymphocyte persistence gives researchers a new variable to manipulate.
“Tumours are often dense and physically difficult for immune cells to penetrate. Understanding how T cells adapt to these environments could help researchers design cancer immunotherapies that are better able to reach and attack tumours,” Mandl noted.
Beyond oncology, decoding mechanosensing pathways could inform new approaches to treating conditions where the immune system mistakenly targets healthy tissue. Autoimmune disorders, allergies, and complications involving transplant rejection all involve T cell activity. Controlling the physical dialogue between cells and tissue could offer therapeutic leverage.
Collaboration across disciplines brought together researchers from the Alan Edwards Centre for Research on Pain, McGill’s Department of Physiology, the McGill University Health Centre, and the Department of Bioengineering, working alongside international colleagues in the United States and the Netherlands. Financial backing came from the U.S. National Institutes of Health, the Canadian Institutes of Health Research, the Human Frontier Science Program, the Natural Sciences and Engineering Research Council of Canada, and the Canadian Foundation for Innovation.
The Hunt for the Cellular Touch Sensor
Despite uncovering this mechanical sensitivity, a critical unknown remains. Researchers hope to identify the specific molecular sensor that enables T cells to detect their physical environment.
Pinpointing this specific sensor serves as the next objective for the group’s ongoing research, which builds on their study published in Nature Immunology. Figuring out the way this sensor translates physical pressure into alterations in cellular activity might shed light on how lasting immune defense is achieved.
