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Bioactive Components from Lactobacillus acidophilus and Lactobacillus helveticus Fermented Milk Enhance Epithelial Membrane Integrity against Salmonella enterica serovars Typhimurium Infection

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Title: Bioactive Components from Lactobacillus acidophilus and Lactobacillus helveticus Fermented Milk Enhance Epithelial Membrane Integrity against Salmonella enterica serovars Typhimurium Infection
Author: Peng, Jingya
Department: Department of Food Science
Program: Food Science
Advisor: Griffiths, Mansel W.
Abstract: Previous in vitro and in vivo studies showed that bioactive components produced by Lactobacillus acidophilus (La-5) and Lactobacillus helveticus (LH-2) exerted protective effects against a variety of enteric pathogens infection, including Salmonella. The purpose of this study is to determine the mechanism of protective effect from La-5 and LH-2 against Salmonella Typhimurium infection on epithelial cells. Cell free spent medium (CFSM) were obtained after 48 h fermentation in whey protein-based medium or milk for La-5 and LH-2, respectively. Human colonic carcinoma HT-29 cells were grown in Transwell inserts for 40 days until they were polarized (TEER ~120 ohm×cm2). Cells were pre-incubated with CFSMs 24 h prior to Salmonella infection and co-incubated during infection. Lactate dehydrogenase (LDH) activity and TUNEL apoptotic assay were tested. Finally, an invasion assay was carried out using chicken hepatoma LMH cells as an in vitro model for Salmonella presence in poultry. Results shown that Salmonella induced TEER loss was attenuated when pre-incubated and co-incubated with non-toxic dose of CFSMs at 8th h post-infection (P <0.05). LDH was reduced up to 49.1% (La-5) and 46.8% (LH-2) (P <0.01). In terms of apoptosis, 75.8% (La-5) and 62.5% (LH-2) less apoptotic cells were observed (P <0.01). The effectiveness of Salmonella invasion on LMH cells was strain dependent. Less than one log10 cycle reduction was obtained when La-5 or LH-2 CFSM was applied. These data suggest that LH-2 and La-5 have antagonized function against Salmonella infection in epithelial cells by enhancing epithelial membrane integrity and would bring further beneficial evidence of consuming bioactives as functional supplements.
URI: http://hdl.handle.net/10214/8120
Date: 2014-05


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