Editors' ChoiceProbiotic bacteria

Lactobacillus Inhibits Apoptosis

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Science's STKE  07 Jan 2003:
Vol. 2003, Issue 164, pp. tw10-TW10
DOI: 10.1126/stke.2003.164.tw10

Yan and Polk investigated the effects of Lactobacillus rhamnosus GG (LGG) on cytokine-induced apoptosis in cultured human and mouse epithelial cells and showed that it promoted cell survival through interactions with both proapoptotic and antiapoptotic signaling pathways. Several species of Lactobacilli, bacteria used in the production of yogurt that can colonize the human gastrointestinal tract, are considered probiotics--microrganisms that benefit the health of the host. Data from humans and from animal models suggest that some Lactobacilli may modulate cytokine activity and help in treating inflammatory bowel disease; the underlying mechanisms, however, remain unclear. The authors initiated apoptosis by treating young adult mouse colon (YAMC) cells stably transfected with dominant-negative kinase-inactive kinase suppressor of Ras (kiKSR) with tumor necrosis factor (TNF) or by treating HT29 human colonic carcinoma cells with a cytokine mixture. Viable LGG bacteria inhibited apoptosis and reduced caspase activity. The presence of LGG stimulated Akt phosphorylation in YAMC and HT29 cells, as did TNF. Inhibitors of phosphatidylinositol 3-kinase inhibited Akt activation by both LGG and TNF, whereas kiKSR expression inhibited only TNF activation of Akt. LGG inhibited TNF-mediated phosphorylation of proapoptotic p38 mitogen-activated protein kinase (p38 MAPK). Pharmacological analysis implicated both Akt activation and p38 MAPK inhibition in blocking TNF-mediated apoptosis. Medium in which LGG bacteria had been incubated inhibited apoptosis and stimulated Akt, and the authors identified two active heat- and protease-sensitive factors that may be involved in the antiapoptotic response.

F. Yan, D. B. Polk, Probiotic bacterium prevents cytokine-induced apoptosis in intestinal epithelial cells. J. Biol. Chem. 277, 50959-50965 (2002). [Abstract] [Full Text]

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