Table 2.

Immunomodulatory properties of secondary bile acids.

Bile acid	Receptor involved	Cellular mechanisms	Effect on disease	References
Innate immunity
DCA	Unknown	Reduces frequency of tuft cells. Increases biliary neutrophilia	Might exacerbate obstructive cholestasis	(37)
DCA	TGR5	Reduces secretion of IL-1β, IL-6, IL-12p70, and TNF-α;	Protects mice against experimental autoimmune uveitis	(29)
TUDCA	Unknown	Reduces surface expression of co-stimulatory molecules (CD40, CD80 and CD86) and MHC-II; Reduces differentiation of Th1/17 Reduces the expression of antigen presentation machinery in the gut; Dampens innate inflammatory response to IFN-γ; Attenuates T-cell activation	Ameliorates intestinal aGvHD disease	(28)
isoDCA	FXR	Modulates dendritic cell function to induce Treg cells	Unknown	(31)
Adaptive immunity
LCA	VDR	Inhibits Th1 cell activation in vitro	Unknown	(32)
3-oxoLCA	RORγt	Inhibits Th17 cell differentiation in vitro and in vivo	Unknown	(33)
isoLCA 3-oxoLCA /isoLCA	RORγt	Inhibits Th17 cell differentiation in vitro and in vivo	3-oxoLCA/isoLCA levels reduced in IBD patients	(34)
isoalloLCA or isoalloLCA/3-oxoLCA	Unknown	Enhances Treg cell differentiation in vitro or in vivo	Unknown	(33)
3-oxoLCA /LCA	VDR	Enhances Treg cell differentiation in vivo	Ameliorates colitis-induced inflammation in mice	(35)