High Dimensional Single-Cell Analysis Reveals iNKT Cell Developmental Trajectories and Effector Fate Decision.

Area of Science:

• Immunology
• Cell Biology
• Developmental Biology

Background:

• Invariant Natural Killer T (iNKT) cells are crucial immune cells with potent effector functions acquired during thymic development.
• The precise developmental pathway and factors governing the emergence of distinct iNKT cell effector subsets remain largely unknown.

Purpose of the Study:

• To elucidate the developmental trajectory of thymic iNKT cells and identify key regulators of effector subset specification.
• To reconcile conflicting models of iNKT cell differentiation.

Main Methods:

• Unbiased single-cell transcriptomic analysis of thymic iNKT cells.
• Functional immunological assays.
• Mathematical modeling of developmental pathways.
• Identification of regulatory transcription factors.

Main Results:

• Revealed significant diversity within thymic iNKT cells, particularly among iNKT1 cells.
• Established a developmental map where iNKT2 cells serve as a transient intermediate for iNKT1 and iNKT17 cell generation.
• Identified Four-and-a-half LIM domains protein 2 (FHL2) as a critical cell-intrinsic regulator for iNKT1 cell specification.

Conclusions:

• Thymic iNKT cell differentiation follows a defined map with iNKT2 cells as a key branching point.
• FHL2 plays a crucial role in the commitment of iNKT cells to the iNKT1 lineage.
• The study highlights the dynamic transcriptional network governing iNKT cell effector fate determination.