Protective immunity against L. monocytogenes infection requires the coordinated action
of a diverse group of immune cells and cytokines (26, 27). Listeria monocytogenes infection led to increased relative spleen weights in the PC and LGG-fed groups, they did not increase in the JWS 833-fed group. Previous studies have reported that decreases in the relative weight of organs such as the spleen are indicative of increased host resistance. Administration of Lactobacillus plantarum reduced the spleen weight in L. monocytogenes-infected mice (29, 31). Meanwhile, the JWS 833-fed group had relatively heavier livers than the PC and LGG-fed groups. An earlier study by Tsai et al. showed a similar result in terms of increased liver weight (32). Rats Fludarabine mw were fed with E. faecium TM39 for 4 weeks at a dose of 1 × 1012 cfu/kg. They found that E. faecium had no adverse effects in terms of changes in the relative weights of the heart, kidney and spleen weight in male or female Wistar rats; however, relative liver weights were higher in the female rats. Moreover, administration of Lactobacillus ingluviei in female BALB/c mice increased body and liver weights;
metabolic changes and amount of mRNA TNF-α was also significantly Selumetinib concentration increased (33). Puertollano et al. injected L. monocytegenes after oral administration of L. plantarum (29). According to them, liver weights were greater in the probiotic-fed than control group, although the difference between the two groups was not statistically significant. In our study, JWS 833-fed mice showed reduced spleen weights, suggesting protection from L. monocytogenes. JWS 833 induced higher serum concentrations
of NO and inflammatory cytokines after L. monocytogenes infection than did LGG. This immunomodulatory effect in JWS 833-fed mice correlated with increased survival rates and mean survival times after L. monocytogenes infection. The number of viable L. monocytogenes in the JWS 833-fed mouse livers was significantly lower than Sodium butyrate in those of the control group. In our study we injected, the mice intravenously with L. monocytogenes. Most recent studies have also used i.v. injections to examine immune responses against L. monocytogenes infection in mice. L. monocytogenes is highly virulent in mice; however, JWS 833-fed mice infected with this bacterium i.v. were partially protected from this lethal infection. Since our goal was to determine whether JWS 833 protects mice from lethal infection with L. monocytogenes, we determined a lethal dose of L. monocytogenes based on published reports and our pilot experiments. Irons et al. (31) and Puertollano et al. (29) injected mice with a lethal dose of 106 cfu of L. monocytogenes; the infected mice died within 48–120 hrs. We carried out pilot experiments to determine the lethal dose of L. monocytogenes in BALB/c mice. We found that mice survived for 120 hr after an i.v. injection of 1.2 × 105 cfu/mouse.