The aim of this study was to investigate the effects of three Lactobacillus plantarum strains on in-vivo small intestinal barrier function and gene transcription in human subjects. The strains were selected for their differential effects on TLR signalling and tight junction protein rearrangement, which may lead to beneficial effects in a stressed human gut mucosa. Ten healthy volunteers participated in four different intervention periods: 7-day oral intake of either L. plantarum WCFS1, CIP48 (CIP104448), TIFN101 (CIP104450) or placebo, proceeded by a 4 weeks wash-out period. Lactulose-rhamnose ratio (an indicator of small intestinal permeability) increased after intake of indomethacin, which was given as an artificial stressor of the gut mucosal barrier (mean ratio 0.060.04 to 0.100.06, p=0.001), but was not significantly affected by the bacterial interventions. However, gene transcription pathway analysis in small intestinal biopsies, obtained by gastroduodenoscopy, demonstrated that particularly L. plantarum TIFN101 modulated cell-cell adhesion with high turnover of genes involved in tight- and adhesion junction protein synthesis and degradation (e.g. actinin alpha-4, metalloproteinase-2). These effects were less pronounced for L. plantarum WCFS1 and CIP104448. In conclusion, L. plantarum TIFN101 induced the most pronounced probiotic properties with specific effects on repair processes in the compromised intestine of healthy subjects.