Gossip in the gut: Quorum sensing, a new player in the host-microbiota interactions

Table 3 Effects of quorum sensing molecules on inflammation in different cell types

Cell type	QS molecule	Effects	Ref.
Effects on innate immune cells
Macrophages	3-oxo-C12-HSL	Anti-inflammatory effects on IL-12 and TNF-α (0.1-100 μmol/L)	Telford et al[94]
		Increased TLR2 and TLR4 expression and decreased TNF-α production (1-100 μmol/L)	Bao et al[180]
		Pro-apoptotic effects (12-50 μmol/L)	Tateda et al[102]
		Increased phagocytosis (100 μmol/L)	Vikström et al[107]
		NF-κB inhibition (4.7 μmol/L)	Kravchenko et al[104]
		Dose-dependent anti-inflammatory effects (1-50 μmol/L)	Kravchenko et al[105]
		Involvement in p38/MAPK signaling (1-100 μmol/L)	Kravchenko et al[105], Vikström et al[107], Glucksam-Galnoy et al[181]
		Activation of the Unfolded Protein Response (6.25-100 μmol/L)	Zhang et al[182]
		Change in cell volume and shape (10-50 μmol/L)	Holm et al[183]
	Indole derivatives	Prevents the induction of pro-inflammatory cytokines	Krishnan et al[184]
	AI-2	Induction of the expression of cytokines, chemokines and TNFSF9	Li et al[41]
Monocytes	AI-3 and analogues	Increase in IL-8 secretion	Kim et al[22]
Dendritic cells	3-oxo-C12-HSL	Pro-apoptotic effects (100 μmol/L)	Boontham et al[185]
		No effect on IL-10 secretion (5-30 μmol/L)	Skindersoe et al[100]
		Increased IL-10 production (5-100 μmol/L)	Li et al[99]
		Decreased IL-12 secretion (5-100 μmol/L)	Li et al[99] and Skindersoe et al[100]
		Increased induction of Treg (5-100 μmol/L)	Li et al[99]
Neutrophils	3-oxo-C12-HSL	Chemoattraction (0.01-100 μmol/L)	Karlsson et al[186] and Zimmermann et al[187]
		Activation of MAPK signaling (12-50 μmol/L)	Tateda et al[102] and Singh et al[188]
		Increased phagocytosis (10 μmol/L)	Wagner et al[189]
		Pro-apoptotic effects (12-50 μmol/L)	Tateda et al[102]
Effects on adaptive immune cells
T cells	3-oxo-C12-HSL	Inhibition of proliferation and activation (0.1-100 μmol/L)	Telford et al[94], Boontham et al[185], Gupta et al[190], and Hooi et al[191]
		Activation of naïve T cells towards Th1 phenotype (5 μmol/L)	Smith et al[95]
		Decreased secretion of IL-4 and IFN-γ (5 μmol/L)	Ritchie et al[96]
		Induction of apoptosis via the mitochondria pathway (100 μmol/L)	Jacobi et al[101]
		Induction of Treg (1-50 μmol/L)	Li et al[99]
	Indole derivatives	Re-programming into tolerogenic T cells	Cervantes-Barragan et al[192]
		Promotion of differentiation towards a regulatory type 1 phenotype	Aoki et al[193]
B cells	3-oxo-C12-HSL	Modulation of immunoglobulin production (0.1-100 μmol/L)	Telford et al[94] and Ritchie et al[194]
ILC	Indole derivatives	Promotion of IL-22 production	Zelante et al[83]
Effects on epithelial cells
Pulmonary tract epithelial cells	3-oxo-C12-HSL	Induction of IL-8 production and NF-B activation (100 μmol/L)	Smith et al[195]
		Increased expression levels of pro-inflammatory cytokines	Jahoor et al[115]
Intestinal epithelial cells	3-oxo-C12-HSL	Mitigation (1-10 μmol/L) or aggravation (> 50 μmol/L) of IL-8 expression induction	Peyrottes et al[92]
	3-oxo-C12:2-HSL	Attenuation of the induction of IL-8 expression (5-50 μmol/L)	Landman et al[39]

AI: Autoinducer; B cells: Lymphocytes B; HSL: Homoserine lactones; IFN-γ: Interferon-γ; IL: Interleukin; ILC: Innate lymphoid cells; MAPK: Mitogen-activated protein kinase; NF-κB: Nuclear factor-kappa B; QS: Quorum sensing; T cells: Lymphocytes T; Th: T helper; TLR: Toll like receptors; TNF-α: Tumor necrosis factor-α; Treg: Regulatory T cells.