The TL1A-DR3 Axis Selectively Drives Effector Functions in Human MAIT Cells

Area of Science:

• Immunology
• Cellular Biology
• Inflammation Research

Background:

• Mucosal-associated invariant T (MAIT) cells are innate immune sentinels recognizing microbial metabolites via MR1.
• MAIT cell functions can be modulated by cytokines independently of T cell receptor (TCR) signaling.
• The role of death receptor 3 (DR3) and its ligand TNF-like protein 1A (TL1A) in MAIT cell activation remains largely unexplored.

Purpose of the Study:

• To investigate the expression and function of the DR3/TL1A axis in human MAIT cells.
• To elucidate the mechanisms by which TL1A influences MAIT cell effector responses.
• To determine the potential contribution of this pathway to inflammatory conditions.

Main Methods:

• Ex vivo analysis of human MAIT cells stimulated with innate cytokines.
• Assessment of DR3 expression and its modulation by TL1A.
• Measurement of MAIT cell cytokine production (TNF-α, IFN-γ) and polyfunctionality.
• Investigation of downstream signaling pathways including NF-κB and p38 MAP kinase.

Main Results:

• DR3 is expressed and upregulated on human MAIT cells by innate cytokine stimulation.
• TL1A stimulation induces innate TNF-α production by MAIT cells independently of TCR ligation.
• TL1A enhances IFN-γ and granzyme B synthesis, augments polyfunctionality, and potentiates T-bet and NF-κB/p38 signaling.
• Bacterial triggering of PBMCs leads to endogenous TL1A release, augmenting MAIT cell effector functions.

Conclusions:

• The DR3/TL1A axis represents a novel inflammatory pathway in MAIT cells.
• This axis amplifies both TCR-dependent and -independent MAIT cell effector functions, notably inducing excessive innate TNF-α production.
• The presence of TL1A and TNF-α in chronic inflammation suggests a significant role for MAIT cells in these settings.