TGF-β Promotes the Postselection Thymic Development and Peripheral Function of IFN-γ-Producing Invariant NKT cells

Area of Science:

• Immunology
• Cell Biology
• Developmental Biology

Background:

• Invariant natural killer T (iNKT) cells are innate-like lymphocytes involved in host defense.
• The specific roles of thymic iNKT cells in immune regulation are not fully understood.
• Subsets of thymic iNKT cells influence various immune cell populations and thymic epithelial cells.

Purpose of the Study:

• To investigate the role of transforming growth factor-beta (TGF-β) signaling in the development and function of thymic invariant NKT1 (iNKT1) cells.
• To identify specific iNKT1 cell subsets that depend on TGF-β for their development and gene expression.
• To compare the TGF-β responsiveness of thymic iNKT1 cells with those in peripheral tissues.

Main Methods:

• Analysis of gene expression profiles in murine thymic iNKT1 cells.
• Assessment of cell surface receptor expression, including CD49a, CD103, and CD69.
• Comparison of TGF-β signaling pathways in iNKT1 cells from thymus, liver, and spleen.

Main Results:

• A subset of murine thymic iNKT1 cells requires TGF-β signaling for postselection development and maintenance of specific genes.
• TGF-β signaling is essential for the expression of adhesion receptors CD49a and CD103 on these iNKT1 cells, but not CD69.
• CD244+ c2 thymic iNKT1 cells, known for IFN-γ production and NK-like characteristics, are part of this TGF-β-responsive population.
• Liver and spleen iNKT1 cells lack the specific TGF-β gene signature found in thymic iNKT1 cells, although TGF-β still influences their phenotype and function.

Conclusions:

• TGF-β signaling plays a critical role in the development and maintenance of a specific subset of thymic iNKT1 cells.
• This study reveals heterogeneity in iNKT1 cell development mechanisms across different tissues.
• A close association exists between a subset of thymic iNKT1 cells and TGF-β-producing cells, supporting their development.