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Picture Courtesy: The Hindu

Context:

The 2025 Nobel Prize in Physiology or Medicine was awarded to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their pioneering work on peripheral immune tolerance and regulatory T cells.

What are Regulatory T cells?

Regulatory T cells (Tregs) are an important group of T cells responsible for controlling the immune system’s activity to ensure it does not attack the body’s own tissues, thereby preventing autoimmune diseases and allergic reactions. They perform this function by releasing anti-inflammatory substances and employing various suppressive methods. However, their immune-suppressing role can sometimes hinder the body’s ability to fight tumours. Tregs are characterized by the expression of the transcription factor FoxP3 and specific surface markers such as high levels of CD25 and low levels of CD127.

Functions:

• Immune Tolerance: Regulatory T cells play a crucial role in preventing the immune system from mistakenly targeting the body’s own cells by suppressing autoreactive immune cells, thereby promoting self-tolerance.

• Anti-Inflammatory Role: Tregs help reduce inflammation by producing anti-inflammatory cytokines such as Interleukin-10 (IL-10) and Transforming Growth Factor-beta (TGF-β), which dampen immune responses. 

• Maintaining Immune Homeostasis: By controlling overactive immune responses, regulatory T cells ensure that the immune system remains balanced and does not cause excessive damage to the body.

Markers:

• FoxP3: A key intracellular transcription factor that identifies Treg cells. 

• CD25high and CD127low: Surface markers that can be used to detect Tregs in routine clinical practice. 

Significance of Regulatory T Cells in Disease

• Autoimmune Disorders: An imbalance or dysfunction of regulatory T cells can result in the immune system attacking the body’s own tissues, contributing to the development of autoimmune diseases. 

• Cancer: Although Tregs protect against autoimmunity, their suppressive effect can also limit the immune system’s ability to fight cancer cells, allowing tumours to grow unchecked. 

• Allergic Reactions: Regulatory T cells help reduce the severity of allergic responses by inhibiting the activation of immune cells involved in allergies. 

• Organ Transplantation: Tregs play a key role in promoting tolerance to transplanted organs by suppressing immune attacks that could lead to graft rejection. 

• Potential in Therapeutics: Due to their regulatory capabilities, Tregs are being explored as targets or tools in developing treatments for autoimmune diseases, allergies, cancer immunotherapy, and transplant rejection. 

Conclusion:

Regulatory T cells are essential guardians of the immune system, maintaining balance by preventing autoimmune diseases, controlling inflammation, and modulating allergic reactions. While their suppressive function can sometimes hinder anti-cancer responses, Tregs play a critical role in transplant tolerance and overall immune homeostasis. 

Source: The Hindu