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Background & Aims:
Positive effects of probiotics on the barrier function of intestinal epithelia have been
reported in various animal models or human cell culture studies. In the framework of DFG research group 438 (“Integrative analysis of modes of action of probiotics in pigs”), we were interested in possible protective mechanisms of probiotics licensed for pigs and in the use of adequate models for this type of study. We compared a human and a porcine cell culture model with regard to their response to incubation with pathogenic E. coli and probiotic E. faecium strains. We assessed the barrier function of the epithelia. We also tested the hypotheses of whether protective or anti- or proinflammatory mechanisms of the cell are activated.
The porcine intestinal epithelial cell line IPEC-J2 and the colon carcinoma cell line Caco-2 were used in parallel. Cells were incubated with various bacterial strains and their combinations (E. faecium NCIMB 10415 and pathogenic E. coli). The transepithelial electrical resistance (TEER) was measured with a voltohmmeter, and mannitol flux rates were concomitantly recorded. Quantitative PCR for the expression of heat shock proteins (Hsps) and cytokines was performed in an iCycler Thermal Cycler (Biorad) with SYBR green
Results: Time dependent changes in TEER in response to bacterial incubation were paralleled by changes in mannitol flux rates. These alterations differed depending on bacterial strains and cell lines. Hsp70 mRNA expression was induced by pathogenic E. coli in Caco-2 cells, whereas no consistent effect could be measured in IPEC-J2 cells within the set time frame (10 h). IL-8 mRNA expression was enhanced after E. coli treatment in
both cell lines. Preincubation with E. faecium ameliorated the effects of pathogenic bacteria. Conclusions: E. faecium might have a protecting effect with regard to the damage caused by E. coli to epithelial function, but these effects differ depending on the cell line.