Fig. 2

The role of ILC3s in SpA. The intestinal mucosa harbors abundant NCR⁺α4β7⁺ILC3s in homeostatic conditions. In inflammatory settings like SpA, NCR⁺α4β7⁺ILC3s expanded and emigrated from gut into circulation and α4β7-ligand expressing synovial tissue via chemokine like CCL20, where they produce inflammatory cytokines such as IL-17, IL-22, and GM-CSF to promote local joint inflammation. In the meantime, ILC3s might acquire ILC1-like properties under stimulation of IL-12