Resveratrol, a polyphenol abundantly found in grapes and red wine, exhibits beneficial health effects due to its anti-inflammatory properties. In the present study, we evaluated the effect of resveratrol on inflammatory responses induced by lipopolysaccharide (LPS) treatment of human intestinal Caco-2 and SW480 cell lines. In the LPS-treated intestinal cells, resveratrol dose-dependently inhibited the expression of inducible NO synthase (iNOS) mRNA as well as protein expression, resulting in a decreased production of NO. In addition, Toll-like receptor-4 expression was significantly diminished in LPS-stimulated cells after resveratrol pre-treatment. To investigate the mechanisms by which resveratrol reduces NO production and iNOS expression, we examined the activation of inhibitor of κB (IκB) in LPS-stimulated intestinal cells. Results demonstrated that resveratrol inhibited the phosphorylation, as well as the degradation, of the IκB complex. Overall, these results show that resveratrol is able to reduce LPS-induced inflammatory responses by intestinal cells, interfering with the activation of NF-κB-dependent molecular mechanisms.

Human milk oligosaccharides (HMO) are considered to influence the composition of the gut microflora in breastfed infants. We investigated direct effects of milk HMO fractions or individual oligosaccharides on proliferation, differentiation and apoptosis in transformed human intestinal cells (HT-29 and Caco-2) and non-transformed small intestinal epithelial crypt cells of fetal origin (human intestinal epithelial cells; HIEC). We observed growth inhibition induced by neutral and acidic HMO fractions in HT-29, Caco-2 and HIEC cells in a dose dependent manner. However, the effects varied between cell lines, i.e. HT-29 and Caco-2 cells were more sensitive than HIEC cells. In HT-29, all 16 individual neutral and acidic oligosaccharides except from the two fucosyllactoses had an inhibitory effect on cell growth. Regarding the induction of differentiation in HT-29 and HIEC cells a threshold concentration was observed at 7·5 mg/ml for neutral and acidic HMO fractions. Among individual oligosaccharides, only sialyllactoses induced differentiation in HT-29 and HIEC cells; no effect neither of fractions nor of individual oligosaccharides was found in Caco-2 cells. A strong induction of apoptosis was only detected in HT-29 and HIEC cells for neutral oligosaccharide but not for acidic fractions. HMO were shown to induce growth inhibition in intestinal cells through two different mechanisms, by suppressing cell cycle progression through induction of differentiation and/or by influencing apoptosis. As the development and maturation of digestive and absorptive processes depend on differentiation our experiments show that oligosaccharides are effective at influencing various stages in gastrointestinal development in vitro.

To evaluate the bioactivity of bovine milk from different stages of lactation on human intestinal tissue, a human fetal small intestinal cell line was used as a model system. Milk samples representing six stages of lactation: days 1, 2–3, 6–7 and weeks 12 and 24 after parturition, 1 week before drying off, and milk-like secretion from two stages of the dry period: 7 weeks and 3–4 weeks before expected calving, were collected from 64 Holstein Friesian cows. The whey fraction of the milk or milk-like secretion was added to the culture medium in concentrations ranging from 0·078% to 10%. The growth-promoting activity of whey was measured by determining the incorporation of [3H]thymidine into DNA for the last 24 h of the culture period. Whey fractions from all six stages of lactation stimulated growth of intestinal cells. The growth-promoting activity of colostrum or milk significantly decreased within the first week after calving. The growth-promoting activity in mature milk increased gradually during lactation to reach a level significantly higher than that obtained with colostrum. The growth-promoting activity of whey from milk-like secretion collected after drying off was lower than that of colostrum. Whey from different stages of lactation contained significantly different concentrations of TGF-β1 (0·5–27 ng/ml) and TGF-β2 (12–1219 ng/ml). However, neither the differences in TGF-β1 and TGF-β2, nor the differences in IGF-I and IGF-binding proteins could fully explain the differences in growth-promoting activity of colostrums or milk from different stages of lactation, suggesting that other factors were also involved. The present study showed that bovine milk contained a number of biologically active components that affected growth and development of human intestinal tissue. The results showed that the growth-promoting activity of colostrum and milk was dependent on the stage of lactation in accordance with previous results obtained with mammary epithelial cells. The changes in growth-promoting activity with stage of lactation were probably related to changes in concentrations of several growth factors.

Probiotic bacteria may provide protection against intestinal damage induced by pathogens, but the underlying mechanisms are still largely unknown. We investigated whether Bifidobacterium animalis MB5 and Lactobacillus rhamnosus GG (LGG) protected intestinal Caco-2 cells from the inflammation-associated response induced by enterotoxigenic Escherichia coli (ETEC) K88, by inhibiting pathogen attachment to the cells, which is the first step of ETEC pathogenicity, and regulating neutrophil recruitment, a crucial component of inflammation. A partial reduction of ETEC adhesion was exerted by probiotics and their culture supernatant fractions either undigested or digested with proteases. ETEC viability was unaffected by the presence of B. animalis, LGG or their supernatant fractions in the culture medium, indicating an absence of probiotic bactericidal activity. Probiotics and their supernatant fractions, either undigested or digested with proteases, strongly inhibited the neutrophil transmigration caused by ETEC. Both B. animalis and LGG counteracted the pathogen-induced up regulation of IL-8, growth-related oncogene-α and epithelial neutrophil-activating peptide-78 gene expression, which are chemokines essential for neutrophil migration. Moreover, the probiotics prevented the ETEC-induced increased expression of IL-1β and TNF-α and decrease of transforming growth factor-α, which are regulators ofchemokine expression. These results indicate that B. animalisMB5 and LGG protect intestinal cells from the inflammation-associated response caused by ETEC K88 by partly reducing pathogen adhesion and by counteracting neutrophil migration, probably through the regulation of chemokine and cytokine expression.