Table 1.

List of probiotic strains improving the intestinal epithelium properties via TJ modulation

Bacterial strain	Mechanism of action	Increased(↑) or decreased(↓) gene/protein expression	Reference
Escherichia coli Nissle 1917	- EcN inhibits the leaky gut condition by upregulation of the zonula occludens-1 (ZO-1) in murine intestinal epithelial cells	↑ZO-1	[74, 83]
	- EcN protects against the increased mucosal permeability in the dextrane sodium sulfate (DSS)-induced colitis murine model	↑ZO-2
	- T84 monolayer cells in vitro treated with EcN showed increased ZO-2 expression and ZO-2 redistribution (concentration at the sites of cellular contacts). The redestribution of ZO-2 seems to be regulated (in part) by activity of the protein kinase C-zeta (PKC-ζ)	For both: gene and protein expression
Lactobacillus rhamnosus GG	In vitro pretreatment of MDCK-I and T84 epithelial cell monolayers with L. rhamnosus GG prevents injuries induced by enterohemorragic Escherichia Coli O157:H7 infections via regulation of ZO-1 (protein expression and distribution) and Claudin-1 (distribution)	↑ZO-1 Protein expression	[39]
		Claudin-1 Protein redistribution only
Lactobacillus casei DN-114001	- In vitro T84 epithelial cell monolayer treated with L. casei are protected against the enteropathogenic Escherichia Coli E2348/69	ZO-1 Protein redistribution only	[55]
	- L. casei inhibits the redistribution of ZO-1 following the infection with E. coli
Streptococcus thermophilus ATCC19258 Lactobacillus acidophilus ATCC4356	Probiotic pretreatment of the human intestinal epithelial cell lines HT29/cl.19A and Caco-2 exposed to Escherichia coli 029:NM maintained the phosphorylation levels of ZO-1, occludin and actinin	ZO-1 Occludin Actinin For all: phosphorylation status only	[62]
Bifidobacterium infantis (From VSL#3 cocktail)	T84 cell lines treated with bioactives released in the medium by B. infantis decreased claudin-2 and phospo-p38 (p-p38) expression, and increased ZO-1, occludin and phospo-ERK (P-ERK) expression	↑ZO-1 ↑Occludin ↑Claudin-4 ↓Claudin-2 ↓P-p38 ↑P-ERK For all: protein expression only	[27]
Lactobacillus plantarum MB452	Caco-2 cells treated with L. plantarum showed increased gene and protein expression of occludin, ZO-1, ZO-2, cingulin, itchy homolog E3 ubiquitin protein ligase (ITCH), snail homolog 1 (SNAI1), and others (reference for complete list)	↑Occludin ↑ZO-1 ↑ZO-2 ↑Cingulin ↑ITCH ↑SNAI1	[1]
Lactobacillus plantarum WCFS1	- Administration of L. plantarum directly in the duodenum of human healthy volunteers showed increased ZO-1 and occludin proteins	↑ZO-1 ↑Occludin TLR-2 (activation)	[41]
	- In in vitro Caco-2 model L. plantarum was shown to activate the Toll-like receptor (TLR)-2 signaling pathway
Lactobacillus plantarum CGMCC No.1258	L. plantarum protected the integrity of Caco-2 monolayer cells against damages by entero-invasive Escherichia coli via TJ proteins regulation (expression and distribution)	↑Claudin-1 ↑Occludin ↑JAM-1 ↑ZO-1	[58]