Tuft cell IL-17RB restrains IL-25 bioavailability and reveals context-dependent ILC2 hypoproliferation

Area of Science:

• Immunology
• Cell Biology
• Microbiology

Background:

• Tuft cells and group 2 innate lymphoid cells (ILC2s) form a critical circuit for type 2 immune responses.
• This circuit is activated by signals like microbe-derived succinate and helminths present in the gut lumen.

Approach:

• Investigated the mechanistic steps of IL-25 production by tuft cells upon succinate detection.
• Examined the roles of IP3R2, Ca2+ flux, and IL-17RB in tuft cell and ILC2 function.
• Assessed the impact of IL-17RB deficiency and prolonged succinate exposure on ILC2 proliferation.

Key Points:

• Succinate detection by tuft cells triggers IL-25 production via IP3R2 and Ca2+ flux.
• Tuft cells constitutively express Il25, maintaining an anticipatory state.
• Tuft cell IL-17RB is essential for restraining IL-25 bioavailability and preventing excessive ILC2 stimulation.
• Deficiency in tuft cell IL-17RB or prolonged succinate exposure leads to ILC2 hypoproliferation.

Conclusions:

• The tuft cell-ILC2 circuit exhibits intricate regulatory dynamics involving IL-25.
• Precise tuning of IL-25 signaling is crucial for appropriate type 2 immune responses to varying luminal conditions.
• This study provides insights into the mechanisms underlying immune cell responses in helminth infections and gut homeostasis.