Single-cell transcriptomic analysis reveals disparate effector differentiation pathways in human T_reg compartment.

Area of Science:

• Immunology
• Cell Biology

Background:

• Human FOXP3⁺ regulatory T (T_reg) cells are vital for maintaining immune tolerance.
• The heterogeneity and differentiation pathways of T_reg cells are not fully understood.

Purpose of the Study:

• To resolve the heterogeneity and differentiation of human T_reg cells using single-cell technologies.
• To identify distinct T_reg subsets and their developmental trajectories in healthy individuals and patients undergoing stem cell transplantation.

Main Methods:

• Single-cell RNA sequencing and T cell receptor sequencing were employed.
• Functional assays were conducted to characterize T_reg subsets.
• Trajectory analysis was used to infer differentiation paths.

Main Results:

• T_reg cells were classified into naïve, activated, and effector stages, with distinct effector subsets identified (e.g., HLA-DR^hi, LIMS1^hi, FOXP3^hi, MKI67^hi).
• Two major differentiation pathways (Path I and Path II) were delineated, leading to FOXP3^hi and MKI67^hi subsets, respectively.
• These pathways and subsets were conserved in stem cell transplant patients, even with functional impairments during acute graft-versus-host disease (aGVHD).

Conclusions:

• This study provides a comprehensive single-cell atlas of human T_reg cell heterogeneity and differentiation.
• The findings enhance our understanding of T_reg cell complexity in both healthy states and disease contexts like aGVHD.