Studies on the effect of an Enterococcus faecium probiotic on T cell populations in peripheral blood and intestinal epithelium and on the susceptibility to Salmonella during a challenge infection with Salmonella Typhimurium in piglets

Effects of dietary Enterococcus faecium NCIMB 11181 supplementation on growth performance and cellular and humoral immune responses in broiler chickens

This study evaluated the effects of dietary Enterococcus faecium NCIMB 11181 on growth performance and immune response in broiler chickens. A total of 360 1-day-old Arbor Acres male birds were randomly assigned to 4 treatments that administered different dosages of E. faecium (0, 5 × 107, 1 × 108, and 2 × 108 CFU E. faecium/kg diet). The results revealed that average daily gain (ADG) changed quadratically, while feed conversion rate (FCR) increased linearly from day 22 to 35 and day 1 to 35 (P < 0.05). Supplementation of E. faecium at 5 × 107CFU/kg diet resulted in increased ADG (P < 0.05) compared with the other groups. Birds fed with 2 × 108 CFU/kg E. faecium exhibited increased peripheral blood lymphocyte proliferation in response to concanavalin A (Con A) (P < 0.05) at day 35 and enhanced skin responses following phytohemagglutinin (PHA) injection (P < 0.05) at 12 h. Serum lysozyme activity at day 21 increased linearly with dietary E. faecium concentration (P < 0.05), the highest activity was observed in the 1 × 108 and the 2 × 108 CFU E. faecium groups (P < 0.01). Serum levels of proinflammatory cytokines IL-1β, IL-2, IL-6, IFN-γ, and anti-inflammatory IL-4, IL-10 changed linearly or quadratically both at the initial and final phases (P < 0.05). In addition, BSA antibody titers were significantly increased following both primary and secondary inoculation when birds were fed with 1 × 108 or 2 × 108 CFU/kg E. faecium (P < 0.05). In comparison with other groups, birds received 5 × 107 CFU E. faecium exhibited the highest levels of serum IgG (P < 0.05) at day 35. Together, our results revealed that broiler diet supplemented with 5 × 107 CFU/kg E. faecium NCIMB 11181 was appropriate in relation to growth performance under normal conditions. Upon administration with higher dosages of E. faecium NCIMB 11181, obvious immune-stimulatory effects were observed following both cell-mediated and humoral immunity.

Influences of quorum-quenching probiotic bacteria on the gut microbial community and immune function in weaning pigs

The aim of this study is to investigate the dynamic gut microbial diversity in weaning swine after administering feed supplemented with probiotic bacteria that specifically inhibit the activity of quorum molecules. Initially, the universal quorum molecule autoinducer-2 (AI-2) bioassay results indicated that AI-2 activity was profoundly inhibited in enterohemorrhagic Escherichia coli (EHEC) O157:H7 in the presence of Lactobacillus acidophilus strain 30SC cell extract, although the growth of EHEC was not affected. Based on plate counting results, bacterial community analysis revealed a specific reduction in coliforms compared to the control, whereas the population of lactobacilli increased in weaning swine in in vivo trials. Supplementation with L. acidophilus strain 30SC did not affect the counts of other communities, such as total aerobes and yeast/mold. In addition, PCR-denaturing gradient gel electrophoresis analysis showed a significant difference in the 16S rRNA gene products after administering L. acidophilus strain 30SC. Selected bands were sequenced, and most of them were identified as uncultured bacterium clones or a Lactobacillus- and Bifidobacterium-specific community. Therefore, our results indicate that quorum-quenching probiotic bacteria can significantly modulate the gut microbiota of swine and these beneficial effects can contribute to the improvement of performance and health in the gastrointestinal tract of weaning pigs.

Influence of medium-chain fatty acids and short-chain organic acids on jejunal morphology and intra-epithelial immune cells in weaned piglets

Medium-chain fatty acids (MCFA) and short-chain organic acids (SOA) are often used as feed additives in piglet diets. There are limited studies in pigs describing the impact of MCFA or SOA on gut morphology and the local immune system. The aim of this study was to investigate whether the supplementation of SOA (0.41% fumaric acid and 0.32% lactic acid), or the combination of SOA with MCFA (0.15% caprylic and capric acid) would have effects on gut morphology and intestinal immune cells in weaned piglets. A total number of 72 weaned piglets were randomly allocated into three experimental groups. Tissue samples of six animals per group were used to investigate the potential impact of the feed additives on villus length and crypt depth of the jejunum and to quantify intra-epithelial lymphocytes (IEL). CD3-positive IEL were determined via immunohistochemistry (IHC) and flow cytometry (FC), whereas CD2-, CD5-, CD8β-, CD16- and γδ TCR-positive IEL were only analysed by FC. The supplementation of MCFA and SOA did not significantly affect morphometric data. The FC data indicated that SOA significantly increased the quantity of CD2^- CD8^- γδ T cells in the jejunum epithelium. Both IHC and FC analyses of pig jejunum confirmed that the majority of IEL expressed the surface marker CD3 and could be classified as cytotoxic T lymphocytes. In conclusion, the data indicated that SOA increased the proportion of CD2^- CD8^- γδ T cells in the jejunal epithelium. Thus, SOA might enable a beneficial effect on the local immunity by increasing the constitutive number of potential effector cells to defeat infectious diseases.

Probiotic Treatment Decreases the Number of CD14-Expressing Cells in Porcine Milk Which Correlates with Several Intestinal Immune Parameters in the Piglets

Modulating the mucosal immune system of neonates by probiotic treatment of their mothers is a promising approach which can only be investigated through the use of animal models. Here, we used sows and their piglets to investigate the impact of a bacterial treatment on the sow's milk and on the neonate piglet intestinal immune system. In previous experiments, feed supplementation of sows with the probiotic Enterococcus faecium NCIMB 10415 during pregnancy and lactation had been shown to affect intestinal microbiota and cytokine expression of the offspring during the suckling and weaning periods. We therefore investigated the composition of the milk from treated sows in comparison to samples from a control group. In treated sows, the amount of lactose increased, and the somatic cell numbers were reduced. In all milk samples, the percentage of cells expressing membranous CD14 (mCD14) was greater than the fractions of immune cells, indicating expression of mCD14 on mammary epithelial cells. However, in the milk of E. faecium-treated sows, mCD14(+) cells were reduced. Furthermore, the number of CD14(+) milk cells was positively correlated with the percentages of B cells and activated T cells in the ileal MLN of the piglets. This study provides evidence for the expression of mCD14 by the porcine mammary epithelium, and suggests an immunological effect of mCD14(+) milk cells on the piglets' intestinal immune system. Our study further suggests that mCD14(+) mammary epithelial cell populations can be modulated by probiotic feed supplementation of the sow.

Dietary Enterococcus faecalis LAB31 improves growth performance, reduces diarrhea, and increases fecal Lactobacillus number of weaned piglets

Lactic acid bacteria (LAB) have been shown to enhance performance of weaned piglets. However, few studies have reported the addition of LAB Enterococcus faecalis as alternatives to growth promoting antibiotics for weaned piglets. This study evaluated the effects of dietary E. faecalis LAB31 on the growth performance, diarrhea incidence, blood parameters, fecal bacterial and Lactobacillus communities in weaned piglets. A total of 360 piglets weaned at 26 ± 2 days of age were randomly allotted to 5 groups (20 pens, with 4 pens for each group) for a trial of 28 days: group N (negative control, without antibiotics or probiotics); group P (Neomycin sulfate, 100 mg/kg feed); groups L, M and H (supplemented with E. faecalis LAB31 0.5×109, 1.0×109, and 2.5×109 CFU/kg feed, respectively). Average daily gain and feed conversion efficiency were found to be higher in group H than in group N, and showed significant differences between group H and group P (P0 < 0.05). Furthermore, groups H and P had a lower diarrhea index than the other three groups (P0 < 0.05). Denaturing gradient gel electrophoresis (DGGE) showed that the application of probiotics to the diet changed the bacterial community, with a higher bacterial diversity in group M than in the other four groups. Real-time PCR revealed that the relative number of Lactobacillus increased by addition of probiotics, and was higher in group H than in group N (P0 < 0.05). However, group-specific PCR-DGGE showed no obvious difference among the five groups in Lactobacillus composition and diversity. Therefore, the dietary addition of E. faecalis LAB31 can improve growth performance, reduce diarrhea, and increase the relative number of Lactobacillus in feces of weaned piglets.

Feeding of the probiotic bacterium Enterococcus faecium NCIMB 10415 differentially affects shedding of enteric viruses in pigs

Effects of probiotic bacteria on viral infections have been described previously. Here, two groups of sows and their piglets were fed with or without feed supplementation of the probiotic bacterium Enterococcus faecium NCIMB 10415. Shedding of enteric viruses naturally occurring in these pigs was analyzed by quantitative real-time RT-PCR. No differences between the groups were recorded for hepatitis E virus, encephalomyocarditis virus and norovirus. In contrast, astrovirus was exclusively detected in the non-supplemented control group. Rotavirus was shedded later and with lower amounts in the probiotic piglet group (p < 0.05); rotavirus-shedding piglets gained less weight than non-infected animals (p < 0.05). Serum titres of anti-rotavirus IgA and IgG antibodies were higher in piglets from the control group, whereas no difference was detected between sow groups. Phenotype analysis of immune cell antigens revealed significant differences of the CD4 and CD8β (p < 0.05) as well as CD8α and CD25 (p < 0.1) T cell populations of the probiotic supplemented group compared to the non-supplemented control group. In addition, differences were evident for CD21/MHCII-positive (p < 0.05) and IgM-positive (p < 0.1) B cell populations. The results indicate that probiotic bacteria could have effects on virus shedding in naturally infected pigs, which depend on the virus type. These effects seem to be caused by immunological changes; however, the distinct mechanism of action remains to be elucidated.