| 1. |
- Maudsdotter, Lisa, 1984-, et al.
(författare)
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Lactobacilli reduce cell cytotoxicity caused by Streptococcus pyogenes by producing lactic acid that degrades the toxic component lipoteichoic acid
- 2011
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Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 55:4, s. 1622-1628
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacilli are known to prevent colonization by many pathogens; nevertheless, the mechanisms of their protective effect are largely unknown. In this work, we investigated the role of lactobacilli during infection of epithelial cells with group A streptococci (GAS). GAS cause a variety of illnesses ranging from noninvasive disease to more severe invasive infections, such as necrotizing fasciitis and toxic shock-like syndrome. Invasion of deeper tissues is facilitated by GAS-induced apoptosis and cell death. We found that lactobacilli inhibit GAS-induced host cell cytotoxicity and shedding of the complement regulator CD46. Further, survival assays demonstrated that lactic acid secreted by lactobacilli is highly bactericidal toward GAS. In addition, lactic acid treatment of GAS, but not heat killing, prior to infection abolishes the cytotoxic effects against human cells. Since lipoteichoic acid (LTA) of GAS is heat resistant and cytotoxic, we explored the effects of lactic acid on LTA. By applying such an approach, we demonstrate that lactic acid reduces epithelial cell damage caused by GAS by degrading both secreted and cell-bound LTA. Taken together, our experiments reveal a mechanism by which lactobacilli prevent pathogen-induced host cell damage.
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| 2. |
- de Klerk, Nele, et al.
(författare)
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Lactobacilli Reduce Helicobacter pylori Attachment to Host Gastric Epithelial Cells by Inhibiting Adhesion Gene Expression
- 2016
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 84:5, s. 1526-1535
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Tidskriftsartikel (refereegranskat)abstract
- The human gastrointestinal tract, including the harsh environment of the stomach, harbors a large variety of bacteria, of which Lactobacillus species are prominent members. The molecular mechanisms by which species of lactobacilli interfere with pathogen colonization are not fully characterized. In this study, we aimed to study the effect of lactobacillus strains upon the initial attachment of Helicobacter pylori to host cells. Here we report a novel mechanism by which lactobacilli inhibit adherence of the gastric pathogen H. pylori. In a screen with Lactobacillus isolates, we found that only a few could reduce adherence of H. pylori to gastric epithelial cells. Decreased attachment was not due to competition for space or to lactobacillus-mediated killing of the pathogen. Instead, we show that lactobacilli act on H. pylori directly by an effector molecule that is released into the medium. This effector molecule acts on H. pylori by inhibiting expression of the adhesin-encoding gene sabA. Finally, we verified that inhibitory lactobacilli reduced H. pylori colonization in an in vivo model. In conclusion, certain Lactobacillus strains affect pathogen adherence by inhibiting sabA expression and thereby reducing H. pylori binding capacity.
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| 3. |
- Forseth, Torbjörn, et al.
(författare)
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Thermal growth performance of juvenile brown trout Salmo trutta : no support for thermal adaptation hypotheses
- 2009
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 74:1, s. 133-149
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Tidskriftsartikel (refereegranskat)abstract
- Using thermal growth data from eight populations of anadromous and lake-feeding brown trout Salmo trutta, hypotheses of adaptation to local optima and countergradient variation in growth were tested. The adaptation to local optima hypothesis suggests that natural selection can shift optimal performance temperatures to match the prevailing temperature in a new or changed thermal niche. In contradiction, the countergradient variation hypothesis suggests that populations from hostile environments perform better than conspecifics from benign environments at all temperatures. In this study, growth capacity varied between populations but there was no significant correlation between any of the estimated thermal performance parameters (e.g. lower and upper thermal growth limits, optimal temperature for growth and maximum growth capacity) and natural climatic conditions among populations. Hence, S. trutta growth response to temperature lends no support for either of the two suggested thermal adaptation hypotheses. Instead, growth capacity among populations tended to correlate positively with female size at maturity.
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| 4. |
- Karimi, Shokoufeh, et al.
(författare)
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In Vivo and In Vitro Detection of Luminescent and Fluorescent Lactobacillus reuteri and Application of Red Fluorescent mCherry for Assessing Plasmid Persistence
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus reuteri is a symbiont that inhabits the gastrointestinal (GI) tract of mammals, and several strains are used as probiotics. After introduction of probiotic strains in a complex ecosystem like the GI tract, keeping track of them is a challenge. The main objectives of this study were to introduce reporter proteins that would enable in vivo and in vitro detection of L. reuteri and increase knowledge about its interactions with the host. We describe for the first time cloning of codon-optimized reporter genes encoding click beetle red luciferase (CBRluc) and red fluorescent protein mCherry in L. reuteri strains ATCC PTA 6475 and R2LC. The plasmid persistence of mCherry-expressing lactobacilli was evaluated by both flow cytometry (FCM) and conventional plate count (PC), and the plasmid loss rates measured by FCM were lower overall than those determined by PC. Neutralization of pH and longer induction duration significantly improved the mCherry signal. The persistency, dose-dependent signal intensity and localization of the recombinant bacteria in the GI tract of mice were studied with an in vivo imaging system (IVIS), which allowed us to detect fluorescence from 6475-CBRluc-mCherry given at a dose of 1x10(10) CFU and luminescence signals at doses ranging from 1x10(5) to 1x10(10) CFU. Both 6475-CBRluc-mCherry and R2LC-CBRluc were localized in the colon 1 and 2 h after ingestion, but the majority of the latter were still found in the stomach, possibly reflecting niche specificity for R2LC. Finally, an in vitro experiment showed that mCherry-producing R2LC adhered efficiently to the intra cellular junctions of cultured IPEC-J2 cells. In conclusion, the two reporter genes CBRluc and mCherry were shown to be suitable markers for biophotonic imaging (BPI) of L. reuteri and may provide useful tools for future studies of in vivo and in vitro interactions between the bacteria and the host.
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| 5. |
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| 6. |
- Li, Hao, 1984-, et al.
(författare)
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Effects of Lactobacillus johnsonii and Lactobacillus reuteri on gut barrier function and heat shock proteins in intestinal porcine epithelial cells
- 2015
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Ingår i: Physiological Reports. - : WILEY. - 2051-817X. ; 3:4
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Tidskriftsartikel (refereegranskat)abstract
- Heat shock proteins (HSPs) are a set of highly conserved proteins that can serve as intestinal gate keepers in gut homeostasis. Here, effects of a probiotic, Lactobacillus rhamnosus GG (LGG), and two novel porcine isolates, Lactobacillus johnsonii strain P47-HY and Lactobacillus reuteri strain P43-HUV, on cyto-protective HSP expression and gut barrier function, were investigated in a porcine IPEC-J2 intestinal epithelial cell line model. The IPEC-J2 cells polarized on a permeable filter exhibited villus-like cell phenotype with development of apical microvilli. Western blot analysis detected HSP expression in IPEC-J2 and revealed that L. johnsonii and L. reuteri strains were able to significantly induce HSP27, despite high basal expression in IPEC-J2, whereas LGG did not. For HSP72, only the supernatant of L. reuteri induced the expression, which was comparable to the heat shock treatment, which indicated that HSP72 expression was more stimulus specific. The protective effect of lactobacilli was further studied in IPEC-J2 under an enterotoxigenic Escherichia coli (ETEC) challenge. ETEC caused intestinal barrier destruction, as reflected by loss of cell-cell contact, reduced IPEC-J2 cell viability and transepithelial electrical resistance, and disruption of tight junction protein zonula occludens-1. In contrast, the L. reuteri treatment substantially counteracted these detrimental effects and preserved the barrier function. L. johnsonii and LGG also achieved barrier protection, partly by directly inhibiting ETEC attachment. Together, the results indicate that specific strains of Lactobacillus can enhance gut barrier function through cytoprotective HSP induction and fortify the cell protection against ETEC challenge through tight junction protein modulation and direct interaction with pathogens.
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| 7. |
- Pallin, Anton, et al.
(författare)
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Evaluation of growth, metabolism and production of potentially bioactive components during fermentation of barley with Lactobacillus reuteri
- 2016
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Ingår i: Food Microbiology. - : Elsevier BV. - 0740-0020 .- 1095-9998. ; 57, s. 159-171
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Tidskriftsartikel (refereegranskat)abstract
- Eighteen bacterial isolates from millet, buckwheat and rye flour were identified as Lactobacillus reuteri. Genomic fingerprinting (rep-PCR) revealed that they represented five strains and phylogenetic analyses using multi locus sequence analysis (MLSA) showed that all clustered with strains of rodent origin. Two strains (SU12-3 and SU18-3) from different phylogenetic clades were used in fermentations of six varieties of barley, both untreated and heat-treated (with inactivated indigenous enzymes) flour. They were compared with two probiotic strains of human origin (DSM 17938 and ATCC PTA 6475), one previously isolated sourdough strain (LTH 5531) and one strain of Lactobacillus plantarum (36E). Analyses of growth (CFU) and metabolism (1H-NMR) revealed differences at species level, with L. plantarum showing a higher capacity to assimilate nutrients without help of the cereal enzymes. Similarities were observed between L. reuteri strains isolated from sourdough, while the greatest differences between L. reuteri strains were observed between strains 6475 and 17938. Multivariate analysis of the metabolic profiles revealed clear clustering according to flour treatment, species of bacteria and barley variety and to some extent also bacterial strain. Possible bioactive compounds such as gamma-aminobutyric acid (GABA), 1,3-propanediol (sign of reuterin production) and histamine were identified and quantified. (C) 2016 Elsevier Ltd. All rights reserved.
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| 8. |
- Pang, Yanhong, et al.
(författare)
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Extracellular membrane vesicles from Limosilactobacillus reuteri strengthen the intestinal epithelial integrity, modulate cytokine responses and antagonize activation of TRPV1
- 2022
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial extracellular membrane vesicles (MV) are potent mediators of microbe-host signals, and they are not only important in host-pathogen interactions but also for the interactions between mutualistic bacteria and their hosts. Studies of MV derived from probiotics could enhance the understanding of these universal signal entities, and here we have studied MV derived from Limosilactobacillus reuteri DSM 17938 and BG-R46. The production of MV increased with cultivation time and after oxygen stress. Mass spectrometry-based proteomics analyses revealed that the MV carried a large number of bacterial cell surface proteins, several predicted to be involved in host-bacteria interactions. A 5 '-nucleotidase, which catalyze the conversion of AMP into the signal molecule adenosine, was one of these and analysis of enzymatic activity showed that L. reuteri BG-R46 derived MV exhibited the highest activity. We also detected the TLR2 activator lipoteichoic acid on the MV. In models for host interactions, we first observed that L. reuteri MV were internalized by Caco-2/HT29-MTX epithelial cells, and in a dose-dependent manner decreased the leakage caused by enterotoxigenic Escherichia coli by up to 65%. Furthermore, the MV upregulated IL-1 beta and IL-6 from peripheral blood mononuclear cells (PBMC), but also dampened IFN-gamma and TNF-alpha responses in PBMC challenged with Staphylococcus aureus. Finally, we showed that MV from the L. reuteri strains have an antagonistic effect on the pain receptor transient receptor potential vanilloid 1 in a model with primary dorsal root ganglion cells from rats. In summary, we have shown that these mobile nanometer scale MV reproduce several biological effects of L. reuteri cells and that the production parameters and selection of strain have an impact on the activity of the MV. This could potentially provide key information for development of innovative and more efficient probiotic products.
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| 9. |
- Roos, Stefan, et al.
(författare)
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Role of Lactobacillus reuteri cell and mucus-binding protein A (CmbA) in adhesion to intestinal epithelial cells and mucus in vitro
- 2014
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Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 160, s. 671-681
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Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus reuteri, a symbiotic inhabitant of the gastrointestinal tract in humans and animals, is marketed as a probiotic. The ability to adhere to intestinal epithelial cells and mucus is an interesting property with regard to probiotic features such as colonization of the gastrointestinal tract and interaction with the host. Here, we present a study performed to elucidate the role of sortase (SrtA), four putative sortase-dependent proteins (SDPs), and one C-terminal membrane-anchored cell surface protein of Lactobacillus reuteri ATCC PTA 6475 in adhesion to Caco-2 cells and mucus in vitro. This included mutagenesis of the genes encoding these proteins and complementation of mutants. A null mutation in hmpref0536_10255 encoding srtA resulted in significantly reduced adhesion to Caco-2 cells and mucus, indicating involvement of SDPs in adhesion. Evaluation of the bacterial adhesion revealed that of the five putative surface protein mutants tested, only a null mutation in the hmpref0536_10633 gene, encoding a putative SDP with an LPxTG motif, resulted in a significant loss of adhesion to both Caco-2 cells and mucus. Complementation with the functional gene on a plasmid restored adhesion to Caco-2 cells. However, complete restoration of adhesion to mucus was not achieved. Overexpression of hmpref0536_10633 in strain ATCC PTA 6475 resulted in an increased adhesion to Caco-2 cells and mucus compared with the WT strain. We conclude from these results that, among the putative surface proteins tested, the protein encoded by hmpref0536_10633 plays a critical role in binding of Lactobacillus reuteri ATCC PTA 6475 to Caco-2 cells and mucus. Based on this, we propose that this LPxTG motif containing protein should be referred to as cell and mucus binding protein A (CmbA).
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| 10. |
- Sellman, Stefan, et al.
(författare)
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Reducing the amount of slaughter transports in modern Swedish cattle production systems
- 2012
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Ingår i: Tackling the Future Challenges of Organic Animal Husbandry. - Braunschweig : Johann Heinrich von Thünen-Institut. - 9783865760944 ; 362, s. 262-265
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Konferensbidrag (refereegranskat)abstract
- Two methods that can help to reduce the distances involved in transportation of cattle to slaughter are presented, route optimization and spatial redistribution of slaughter capacities. In a comparison ot three route optimization techniques we show that RuttOpt is the most effective and that the number of stops on routes can be reduced compared to what is the case today. We also find that transport distances can be reduced by 40 % compared to the real transports of 2008 if animals are sent to the closest available facilities. We believe that the metods highlighted here can help improve the sustainability and animal health in both organic and conventional farming.
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