Core Insights - The 2025 Nobel Prize in Physiology or Medicine was awarded to Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their discovery and definition of regulatory T cells (Treg cells), highlighting their role in preventing the immune system from attacking its own tissues, thus establishing a new field of Treg-mediated peripheral immune tolerance [2] Group 1: Research Findings on Treg Cells - A recent study published in Nature Immunology by researchers from Yale University and the Memorial Sloan Kettering Cancer Center revealed the context-dependent requirements for the transcription factor Foxp3 in Treg cells, indicating that Foxp3 is essential for newly generated Treg cells but less critical for mature Treg cells, except in stressful environments like severe inflammation or tumors [3][6] - The study utilized a technique called "chemical genetic induction of protein degradation" to precisely degrade Foxp3 in live animals, allowing for a better understanding of its role at specific stages and in specific environments [7] Group 2: Key Roles of Foxp3 - Foxp3 acts as a "training instructor" for newly generated Treg cells, as its removal prevents the establishment of the unique gene expression program and suppressive function characteristic of Treg cells, confirming its foundational role [8] - Mature Treg cells exhibit remarkable resilience; even in the absence of Foxp3 under steady-state conditions, their gene expression and suppressive functions show only minor changes, indicating that their immune suppressive capabilities become largely independent of Foxp3 once fully matured [9] - In stressful environments, such as severe inflammation, the loss of Foxp3 in mature Treg cells leads to significant disruptions in gene expression and cellular fitness, highlighting the renewed dependence on Foxp3 under immune stress [9] Group 3: Implications for Cancer Immunotherapy - Treg cells within tumors are particularly sensitive to Foxp3 degradation; its removal significantly weakens their suppressive function, leading to tumor shrinkage without causing severe autoimmune side effects, suggesting a promising avenue for cancer immunotherapy [10] - The study emphasizes that the role of Foxp3 is not static but varies with the life stage of Treg cells and the external immune environment, providing mechanistic insights into why Treg cells may become "ineffective" in autoimmune diseases and severe infections [10]

Core Viewpoint - The article discusses the groundbreaking discoveries by Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi, who were awarded the 2025 Nobel Prize in Physiology or Medicine for their work on regulatory T cells (Treg cells) and their role in peripheral immune tolerance, significantly enhancing the understanding of immune regulation and its implications for autoimmune diseases and cancer [3][11][19]. Group 1: Key Discoveries - The researchers identified and defined CD4+ CD25+ FOXP3+ regulatory T cells (Treg cells) and their critical role in controlling self-reactive responses, leading to the establishment of a new field of study in immune tolerance [3][11][19]. - Shimon Sakaguchi made the first key discovery in 1995, demonstrating that immune tolerance is more complex than previously thought, revealing a previously unknown T cell type that protects against autoimmune diseases [11][14]. - In 2001, Brunkow and Ramsdell discovered a gene mutation in specific mouse strains that made them prone to autoimmune diseases, naming the gene Foxp3, which is also linked to a severe autoimmune disease in humans known as IPEX syndrome [14][18]. Group 2: Implications and Future Directions - The findings of these researchers have opened new avenues in the treatment of cancer and autoimmune diseases, with potential to improve organ transplant success rates, as therapies based on their discoveries are currently in clinical trials [19][20]. - There are over 200 clinical trials involving Treg cells aimed at treating common diseases such as asthma, inflammatory bowel disease, and skin-related conditions, or improving organ transplant outcomes [23]. - The achievements of Brunkow, Ramsdell, and Sakaguchi highlight the importance of scientific perseverance and the integration of clinical observations with basic research, paving the way for enhanced understanding and therapeutic applications of Treg cells [24].