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J Med Microbiol. 2018 Jun 7. doi: 10.1099/jmm.0.000762. [Epub ahead of print]

Lactobacillus plantarum ameliorates tumour necrosis factor-induced bacterial translocation in Caco-2 cells by regulation of TLR4 expression.

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2​Department of Travel Health, Nanjing Entry-Exit Inspection and Quarantine Bureau, Nanjing, Jiangsu 211106, PR China.
1​Jiangsu Academy of Science and Technology for Inspection and Quarantine, Nanjing, Jiangsu 210001, PR China.
3​Department of Ultrasound, Nanjing Hospital of Armed Police Force Corps, Nanjing, Jiangsu 210028, PR China.
4​Research Institute of General Surgery, Jinling Hospital, Nanjing, Jiangsu 210002, PR China.



Translocation of bacteria across the intestinal barrier is important in the pathogenesis of systemic sepsis. In inflammatory conditions, commensal bacteria exploit transcytotic pathways to cross the intestinal epithelium in a TLR4-dependent manner. The aim of this study was to test the hypothesis that Lactobacillus plantarum ameliorates tumour necrosis factor-induced bacterial translocation by regulation of Toll-like receptor-4 expression.


L. plantarum strains were investigated to determine their capacity to inhibit the initial adhesion of Escherichia coli B5 to Caco-2 cells. The inhibitory effects of L. plantarum on TNF-α-induced E. coli B5 translocation across Caco-2 cells were studied. Barrier function and integrity were simultaneously assessed by transepithelial electrical resistance, HRP permeability, LDH release and distribution of tight junctional proteins. Expression of TLR4 was assessed by RT-PCR.Results/Key findings. Pretreatment of monolayers with L. plantarum L2 led to a significant decrease in E. coli B5 adhesion and cell internalization (P<0.01). Exposure to TNF-α for six hours caused a significant increase in E. coli B5 translocation across Caco-2 cells, which was uncoupled from increases in paracellular permeability and disruption of tight junction proteins. Manipulations that induced bacterial translocation were associated with a marked increase in TLR4 mRNA expression and IL-8 secretion. L. plantarum L2 significantly abrogated TNF-α-induced bacterial translocation of E. coli B5, and also downregulated expression of TLR4 and IL-8 in intestinal epithelial cells.


Live L. plantarum L2 can inhibit TNF-α-induced transcellular bacterial translocation via regulation of TLR4 expression.


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