The thymus is essential for producing the T cells that protect us from infections and cancer. But this organ is also highly sensitive to damage. Treatments like chemotherapy, radiation, and hematopoietic cell transplantation can severely deplete thymic cells, leaving patients temporarily immunocompromised and vulnerable to infection or disease relapse. Compounding this challenge, the thymus naturally shrinks and loses function with age, limiting its ability to replenish the pool of naïve T cells needed to respond to new pathogens and vaccines.
Despite these vulnerabilities, the thymus has a remarkable ability to repair itself after injury. Emerging evidence suggests that the way cells die can influence how this regenerative response is triggered. Cell death generally occurs via two primary mechanisms: apoptosis, the “silent” form of cell death which does not trigger inflammation, and pyroptosis, an inflammatory form of cell death that releases danger signals such as damage-associated molecular patterns (DAMPs). These DAMPs include ATP, and in the context of the inflammatory response they act in a similar manner to smoke setting off a fire alarm.
In a new study published in Cell Death & Disease, researchers from the Dudakov lab lead by former staff scientist Sinéad Kinsella investigated how cellular stress and death via pyroptosis following thymic injury might initiate this regenerative response. Previous studies from this group have shown that regenerative signals such as IL-23 and BMP4 help restore thymic function by supporting thymic epithelial cells (TECs)—the specialized stromal cells that guide T cell development. But this study identifies a new player in the process: signals released by dying thymocytes, particularly extracellular ATP.
To test whether inflammatory cell death could directly stimulate thymic repair programs, Kinsella induced pyroptosis in thymocytes and co-cultured them with thymic epithelial cells. They found that pyroptotic thymocytes selectively increased expression of FOXN1, the master transcription factor for TEC function. These findings suggest that signals released during pyroptotic cell death—such as extracellular ATP—can directly activate regenerative pathways in the thymic microenvironment.
Kinsella and team, aided by lab technician Cindy Evandy, next investigated how extracellular ATP promotes FOXN1 expression in thymic epithelial cells. They found that ATP activates P2Y2 purinergic receptor signaling in cortical TECs, triggering intracellular calcium release that correlates with increased FOXN1 transcription. Blocking P2Y2 activity—either pharmacologically or through gene knockdown—significantly reduced ATP-induced FOXN1 expression, confirming that this receptor is a key mediator of the response. Further experiments showed that ATP stimulation activates the ERK signaling pathway downstream of P2Y2, establishing a P2Y2–Ca²⁺–ERK signaling axis that links damage-associated ATP release to thymic epithelial regeneration.
Finally, the researchers asked whether activating this pathway could enhance thymic recovery after injury. Using a specific agonist of the P2Y2 purinergic receptor, UTPγS, they showed that stimulating P2Y2 signaling increased expression of FOXN1 in cortical TECs, while pharmacological inhibition blocked this effect. When UTPγS was administered to mice after irradiation-induced thymic damage, treated animals exhibited significantly improved thymic regeneration, including increased thymic cellularity and enhanced recovery of developing T cell populations. The treatment also boosted regeneration of TECs, supporting the idea that activating P2Y2 signaling can stimulate the epithelial repair programs required to rebuild the thymus after injury.
Kinsella’s findings reveal an unexpected link between inflammatory cell death and thymic regeneration, identifying P2Y2 signaling as a potential therapeutic target. In particular, stimulating this pathway may help restore T cell production more quickly after hematopoietic cell transplantation, when delayed immune reconstitution leaves patients vulnerable to infection. By accelerating rebuilding of the thymic microenvironment, therapies that activate P2Y2 signaling could help shorten the window of immune vulnerability following transplant conditioning.
Fred Hutch/University of Washington/Seattle Children’s Cancer Consortium Members Drs. Lorenzo Iovino, Lucas Sullivan, and Jarrod Dudakov contributed to this research.
The spotlighted research was funded by the National Institutes of Health, the American Society of Hematology, the DKMS Foundation for Giving Life, the Cuyamaca Foundation, the Bezos Family Foundation, the American Society for Transplantation and Cellular Therapy, the Italian Association for Cancer Research, and the Italian Ministry of Health.
Kinsella S, Evandy CA, Cooper K, Kirsche E, Warren M, deRoos P, Cardinale A, Iovino L, Granadier D, Smith CW, Hopwo K, Sullivan LB, Velardi E, Dudakov JA. 2026. Damage-induced pyroptosis drives endogenous thymic regeneration by activating the purinergic receptor P2Y2. Cell Death & Disease. https://doi.org/10.1038/s41419-025-08345-x.
Science Spotlight writer Jenny Waters is a postdoctoral research fellow in the Hsieh lab at Fred Hutch. She studies how mRNA translation coordinates bladder cancer transformation and metastasis by post-transcriptionally regulating expression of oncogenic proteins. Outside of the lab, Jenny enjoys spending time with her dogs, convincing her husband to join her on trail runs, and pretending every steep hill is just a "gentle incline."
For the Media