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

Table 2 Effects of quorum sensing molecules on different parameters of the intestinal epithelial barrier function

QS molecule	Effects	Ref.
Effects on the intestinal epithelial migration
3-oxo-C12-HSL	Increased migration at low concentrations (1.5-12 μmol/L) vs inhibition at 200 μmol/L	Karlsson et al[72]
	Interaction with IQGAP1 and increase in Rac1/Cdc42 (1.5-200 μmol/L)	Karlsson et al[72]
Effects on the intestinal epithelial permeability and intercellular junctions
3-oxo-C12-HSL	Increased permeability to ions and macromolecules (100-400 μmol/L)	Eum et al[55], Vikström et al[58-60], and Aguanno et al[61]
	Activation of p38 and p42/44 and calcium signaling (100-200 μmol/L)	Vikström et al[58-60]
	Decreased expression levels of tight junction genes (100-400 μmol/L); Disassembly of tight and adherens junctions (modification of their phosphorylation status and involvement of MMP-2 and -3)	Eum et al[55], Vikström et al[58-60], and Aguanno et al[61]
	Decreased levels of tight junction proteins occludin and tricellulin (100-400 μmol/L)	Eum et al[55]
	Decreased protein levels of extracellular matrix and tight junction proteins (400 μmol/L)	Tao et al[62]
3-oxo-C12:2-HSL	No deleterious effects on permeabilityProtection of tight junction integrity and maintenance of junctional complexes at the plasma membrane under pro-inflammatory conditions	Landman et al[39] and Aguanno et al[61]
3-oxo-C14-HSL	Decreased protein levels of extracellular matrix and tight junction proteins (400 μmol/L)	Tao et al[62]
Indole and indole derivatives	Decreased permeability to ions and increased expression of genes coding tight junction and cytoskeleton proteins	Bansal et al[76] and Shimada et al[77]
	Decreased permeability to macromolecules	Venkatesh et al[79]
	Increased transcripts levels of genes coding tight junction proteins	Shin et al[78]
Effects on the mucus layer components
3-oxo-C12-HSL	Decreased MUC3 mRNA levels (30 μmol/L)	Taguchi et al[70]
	Decrease in Muc2 production in goblet cell-like cell line (100 μmol/L) vs increase in colonic cell line (400 μmol/L)	Tao et al[67]
Indole	Increased expression of genes involved in the production of mucins	Bansal et al[76]
Effects on intestinal epithelial cell viability
3-oxo-C12-HSL	Mitochondrial dysfunction and induction of apoptosis in goblet cell-like cell line (100 μmol/L) and in colonic cell line (30-100 μmol/L)	Tao et al[67-69], and Taguchi et al[70]
	Induction of apoptosis, mitochondrial dysfunction, oxidative stress and blocking of cell cycle (400 μmol/L)	Tao et al[62]
3-oxo-C14-HSL	Induction of apoptosis, mitochondrial dysfunction, oxidative stress and blocking of cell cycle (400 μmol/L)	Eum et al[55], Vikström et al[58-60], Aguanno et al[61], and Tao et al[62]
CSF	Reduction of oxidative stress-induced cell death and loss of the epithelial barrier (involving HSP27 and p38/MAPK pathway)	Fujiya et al[74]

CSF: Competence and sporulation factor; HSL: Homoserine lactones; HSP27: Heat shock protein 27; IQGAP1: IQ motif containing GTPase activating protein 1; MAPK: Mitogen-activated protein kinase; MMP-2/-3: Matrix metalloproteinase-2/-3; MUC: Mucin; QS: Quorum sensing; Rac1/Cdc42: Ras-related C3 botulinum toxin substrate 1/cell division control protein 42 homolog.