Oral ingestion of lactic-acid bacteria by rats increases lymphocyte proliferation and interferon-γ production

The effect of feeding lactic-acid bacteria on indices of functions of lymphocytes obtained from Peyer's patches, peripheral blood and spleen from inbred Wistar-Furth rats were studied. Rats were fed on purified diets supplemented with 350 g milk or yoghurt/kg diet for 4 weeks. At the end of the feeding period, immune cells from the three sites were isolated and proliferation, interferon-γ production and lymphocyte subset composition were studied. Rats consuming yoghurt had a greater in vitro proliferative response to yoghurt bacteria in the three lymphoid compartments, a greater interferon-γ production in response to bacteria and concanavalin A in Peyer's patches and spleen, and a greater number of Peyer's patches B lymphocytes than milk-fed rats. Macrophage and T lymphocyte proportions and lymphocyte subset composition in the three sites were unaffected by yoghurt. These results indicate that feeding live bacteria contained in yoghurt may interact with the intestinal immune system, and influence the systemic immune system.We thank the Centre Daniel Carasso for supplying bacterial preparations and EU STD3 program no. TS3-CT94-0282 for their financial support of this work.Peer reviewe

Effects of lactoferrin on intestinal epithelial cell growth and differentiation: an in vivo and in vitro study

This study was designed to analyse the effects of human (h) and bovine lactoferrin (bLF) on the growth and differentiation of intestinal cells using the mice model supplemented with Lactoferrin (LF) and the enterocyte-like model of Caco-2 cells which spontaneously differentiate after confluency. In mice, bLF supplementation increased jejunal villus height and the expression of several intestinal brush border membrane enzymes activities. Addition of bLF or hLF to undifferentiated Caco-2 cells was able to increase cell proliferation with confluency being reached more rapidly. Moreover, when Caco-2 cells were grown in the presence of LF for 3 weeks, brush-border membrane-associated enzyme activities i.e. sucrase, alkaline phosphatase and neutral aminopeptidase, as well as the l-glutamate transporter expression were all increased indicating an increased Caco-2 cell differentiation. Accordingly, cDNA Atlas array and Western blot analysis of cell cycle proteins shown a decreased expression of Cdck2 and an increased TAF1 expression; these proteins being implicated in the regulation of numerous genes related to cellular proliferation and differentiation. These modifications were associated with an inhibition of Caco-2 cell spontaneous apoptosis. Altogether, our results indicate that LF increase in vivo and in vitro enterocyte differentiation. In addition, LF was found to increase in vitro enterocyte proliferation resulting in higher cell density in cell flasks, an effect that was likely partly due to a reduction of the cellular apoptosis. The different stimulation patterns observed for the different parameters associated with cell differentiation in relationship with specific gene regulation is discussed