Efficient IL-2R signaling differentially affects the stability, function, and composition of the regulatory T-cell...

Area of Science:

• Immunology
• Cell Biology
• Genetics

Background:

• Interleukin-2 receptor (IL-2R) signaling is crucial for regulatory T (Treg) cell function.
• The precise role of IL-2R signaling in Treg cell homeostasis and stability under varying conditions remains incompletely understood.

Purpose of the Study:

• To investigate the impact of diminished IL-2R signaling on Treg cell identity, homeostasis, lineage stability, and function.
• To characterize a novel mouse model with a hypomorphic CD25 variant affecting IL-2R signaling.

Main Methods:

• Characterization of a spontaneous mutant mouse strain (Cd25^Y129H) with reduced IL-2R signaling.
• Analysis of Treg cell numbers, Foxp3 expression, and immune suppression in non-inflammatory and inflammatory (T-cell transfer colitis) models.
• Single-cell RNA sequencing to assess Treg cell subset heterogeneity.

Main Results:

• Cd25^Y129H mice exhibited reduced peripheral Treg cell numbers with stable Foxp3 expression, preventing autoimmune disease under non-inflammatory conditions.
• In a colitis model, Cd25^Y129H Treg cells showed impaired immune suppression and lost lineage commitment, highlighting the need for unimpaired IL-2R signaling during inflammation.
• Single-cell RNA sequencing revealed that impaired IL-2R signaling significantly altered the balance of central and effector Treg cell subsets.

Conclusions:

• Partial loss of IL-2R signaling differentially impacts Treg cell maintenance, heterogeneity, and suppressive function.
• Unimpaired IL-2R signaling is critical for Treg cell function, particularly in inflammatory environments.
• The study provides insights into the complex role of IL-2R signaling in Treg cell biology and immune regulation.