Table 1.

Markers of intestinal Treg cells and the gist of their phenotype translated to intestinal immune homeostasis.

Marker	Induction	Function
IL-10	Induced by microbiome (41).	Regulates Th1 response (42, 43).
	Requires innate immune cells (44).
	Requires BLIMP-1 for function (45).	Controls Th17-type inflammation in the colon via STAT3 (46–48).
Rorγt	Induced in the colon by microbiome (49).	Controls Th1-type and Th-17 type inflammation (50).
	To lesser extent, may be induced by dietary antigens in absence of microbiome (51).
IL-1R		Characteristic of unstable Treg cells (52, 53).
IL-33R		Associated with tissue repair (54).
		Characteristic of stable Treg cells (52).
IL-23R		Inhibits IL-33 responsiveness (54).
		Function in intestine unknown.
GATA3	Decreased in absence of CNS1 (55).	Controls spontaneous Th2-type enteritis (55).
	Induced by high affinity TCR ligands (55).	GATA3-deficient Treg cells produce more IL17A (56).
HELIOS	Supported by IL-33 (50).	Proposed marker for tTreg cells (57).
NRP1	Expressed during inflammation (58).	Proposed marker for tTreg cells (58, 59).
		Promotes Treg cell activity (60, 61).