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  • Boal, Frédéric, et al. (författare)
  • PI5P Triggers ICAM-1 Degradation in Shigella Infected Cells, Thus Dampening Immune Cell Recruitment
  • 2016
  • Ingår i: Cell reports. - : Cell Press. - 2211-1247 .- 2211-1247. ; 14:4, s. 750-759
  • Tidskriftsartikel (refereegranskat)abstract
    • Shigella flexneri, the pathogen responsible for bacillary dysentery, has evolved multiple strategies to control the inflammatory response. Here, we show that Shigella subverts the subcellular trafficking of the intercellular adhesion molecule-1 (ICAM-1), a key molecule in immune cell recruitment, in a mechanism dependent on the injected bacterial enzyme IpgD and its product, the lipid mediator PI5P. Overexpression of IpgD, but not a phosphatase dead mutant, induced the internalization and the degradation of ICAM-1 in intestinal epithelial cells. Remarkably, addition of permeant PI5P reproduced IpgD effects and led to the inhibition of neutrophil recruitment. Finally, these results were confirmed in an in vivo model of Shigella infection where IpgD-dependent ICAM-1 internalization reduced neutrophil adhesion. In conclusion, we describe here an immune evasion mechanism used by the pathogen Shigella to divert the host cell trafficking machinery in order to reduce immune cell recruitment.
  • Dziedziech, Alexis, 1991- (författare)
  • Timing Matters : Wounding and entomopathogenic nematode infection kinetics
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Over time, insects have developed complex strategies to defend themselves against presenting threats. However, in the evolutionary arms race of survival, pathogens have adapted to quickly overcome the immune response mounted by the host. In this thesis, we assess how quickly entomopathogenic nematodes (EPNs) can overcome the host, Drosophila melanogaster. We then look at the clotting reaction at a hypothetical point of entry for the nematode and bring resolution to the order of protein interaction focusing on three proteins important in the anti-nematode defense. Finally, we look closer into detail at how crystal cells secrete one of those proteins, prophenoloxidase (PPOII) using a mode of programmed cell death. (Paper I) In the course of EPN infection, little was known about how quickly the worms can overcome the host immune system. Here we found that after penetrating the host, EPNs cause septicemia within 4 to 6 hours. (Paper II) Three proteins, Glutactin (Glt), Transglutaminase (Tg), and PPOII have been found to be important in the anti-nematode response. Here we created GFP-tagged fly constructs to follow their role in clot formation. In early clot formation, Tg was immediately secreted from hemocytes though it was localized around the cell membrane, Glt then entered clot fibers followed by PPOII which acted in late clot formation. (Paper III) Here we looked closer into Tg and PPOII secretion variability. PPOII from immature, but not mature crystal cells colocalized with a membrane marker. Tg, when driven with a pan tissue driver, was found located in clotting fibers, in contrast with paper II. (Paper IV) In an in vivo immune scenario, crystal cells were recruited to the wound site and burst rapidly in a caspase-dependent manner. We demonstrate that the mode of programmed cell death, pyroptosis, exists in Drosophila by way of convergent evolution.This thesis brings to light the variation found within the infection process for EPNs as well as the clotting response based on larval age, tissue type, and the maturity of a single cell type. Timing in each of these immune scenarios can give very different indications about the kind of immune response mounted and even the role of an individual cell.
  • Pang, Yanhong, et al. (författare)
  • Extracellular membrane vesicles from Limosilactobacillus reuteri strengthen the intestinal epithelial integrity, modulate cytokine responses and antagonize activation of TRPV1
  • 2022
  • Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X .- 1664-302X. ; 13
  • 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.
  • Valanne, Susanna, et al. (författare)
  • Genome-wide RNA interference in Drosophila cells identifies G protein-coupled receptor kinase 2 as a conserved regulator of NF-κB signaling
  • 2010
  • Ingår i: Journal of Immunology. - : American association of immunologists. - 0022-1767 .- 1550-6606. ; 184:11, s. 6188-6198
  • Tidskriftsartikel (refereegranskat)abstract
    • Because NF-kappaB signaling pathways are highly conserved in evolution, the fruit fly Drosophila melanogaster provides a good model to study these cascades. We carried out an RNA interference (RNAi)-based genome-wide in vitro reporter assay screen in Drosophila for components of NF-kappaB pathways. We analyzed 16,025 dsRNA-treatments and identified 10 novel NF-kappaB regulators. Of these, nine dsRNA-treatments affect primarily the Toll pathway. G protein-coupled receptor kinase (Gprk)2, CG15737/Toll pathway activation mediating protein, and u-shaped were required for normal Drosomycin response in vivo. Interaction studies revealed that Gprk2 interacts with the Drosophila IkappaB homolog Cactus, but is not required in Cactus degradation, indicating a novel mechanism for NF-kappaB regulation. Morpholino silencing of the zebrafish ortholog of Gprk2 in fish embryos caused impaired cytokine expression after Escherichia coli infection, indicating a conserved role in NF-kappaB signaling. Moreover, small interfering RNA silencing of the human ortholog GRK5 in HeLa cells impaired NF-kappaB reporter activity. Gprk2 RNAi flies are susceptible to infection with Enterococcus faecalis and Gprk2 RNAi rescues Toll(10b)-induced blood cell activation in Drosophila larvae in vivo. We conclude that Gprk2/GRK5 has an evolutionarily conserved role in regulating NF-kappaB signaling.
  • Gustafsson, Lars, et al. (författare)
  • Infectious disease, reproductive effort and the cost of reproduction in birds
  • 1994
  • Ingår i: Philosophical transactions of the Royal Society of London: Series B. ; :346, s. 1655-1658
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • Reproductive effort can have profound effects on subsequent performance. Field experiments on the collared flycatcher (Ficedula albicollis) have demonstrated a number of trade-offs between life-history traits at different ages. The mechanism by which reproductive effort is mediated into future reproductive performance remains obscure. Anti-parasite adaptations such as cell-mediated immunity may probably also be costly. Hence the possibility exists of a trade-off between reproductive effort and the ability to resist parasitic infection. Serological tests on unmanipulated collared flycatchers show that pre-breeding nutritional status correlates positively with reproductive success and negatively with susceptibility to parasitism (viruses, bacteria and protozoan parasites). Both immune response and several indicators of infectious disease correlate negatively with reproductive success. Similar relations are found between secondary sexual characters and infection parameters. For brood-size-manipulated birds there was a significant interaction between experimentally increased reproductive effort and parasitic infection rate with regard to both current and future fecundity. It seems possible that the interaction between parasitic infection, nutrition and reproductive effort can be an important mechanism in the ultimate shaping of life-history variation in avian populations.
  • Andersson, Måns Sverker, et al. (författare)
  • Glycosylated haemoglobin: a new measure of condition in birds
  • 1995
  • Ingår i: Proceedings of the Royal Society of London. ; :260, s. 299-303
  • Tidskriftsartikel (refereegranskat)abstract
    • Abstract: The influence of condition on time of breeding and reproductive success has been discussed since Darwin first suggested a relation in 1871. We used a novel method to investigate the influence of condition on the timing of breeding and reproductive success by measuring a relatively inert physiological parameter - the amount of glycosylated haemoglobin - in blood samples taken from the collared flycatcher Ficedula albicollis. The percentage of glycosylated haemoglobin (%HbG) was assumed to be proportional to the average blood glucose level, during the 3-5 weeks before the blood sampling. The %HbG was influenced neither by sex nor age. Date of arrival at the breeding ground was negatively correlated with %HbG so that early-arriving birds had significantly higher %HbG than those arriving later. Clutch size, corrected for the effect of laying date, correlated positively with %HbG in females, as did the number of fledged young, corrected for the effect of laying date, for both sexes. We found no correlation between body mass and the %HbG. We suggest that prebreeding condition influences the timing of breeding and subsequent reproductive performance and that %HbG can be used as an indicator of prebreeding-condition in migrating birds.
  • Franz, F, et al. (författare)
  • The Transcriptional Regulation of FOXO Genes in Thyrocytes.
  • 2016
  • Ingår i: Hormone and Metabolic Research. - Stuttgart : Georg Thieme Verlag. - 0018-5043 .- 1439-4286. ; 48:9, s. 601-6
  • Tidskriftsartikel (refereegranskat)abstract
    • FOXO transcription factors are key regulators of DNA damage repair, proliferation and apoptosis in thyrocytes. Thyroid malignancies show impaired FOXO function. In this study, we investigated the transcriptional regulation of FOXO isoforms in thyroid epithelial cells. mRNA expression of FOXO isoforms (FOXO1, 3 and 4) was determined in FRTL-5 cells stimulated with different growth factors and H2O2. Furthermore, the impact of PI3K/AKT signalling on FOXO transcription was investigated in PI3K p110α mutant FRTL-5 cells and regulatory dependence of FOXO transcription on FOXO was studied in FRTL-5 cells with hFOXO3 overexpression. Finally, mRNA expression levels of FOXO isoforms were determined in human epithelial thyroid tumours. Growth factor deprivation induced transcription of FOXO1, 3 and 4, whereas insulin stimulation decreased FOXO1 and FOXO4 transcription in FRTL-5 cells. Inhibition of the PI3K/AKT cascade amplified FOXO1 and FOXO4 expression. In contrast, H2O2 and TSH did not influence FOXO transcription in thyrocytes. Overexpression of PI3K p110α inhibited FOXO3 and induced FOXO4 transcription. In human thyroid tumours, FOXO1 and FOXO3 mRNA levels were significantly downregulated in papillary thyroid carcinoma when compared to normal tissues. In contrast, follicular thyroid carcinomas showed significant upregulation of FOXO4 mRNA.In this paper, we demonstrate an influence of PI3K signalling on FOXO transcription in thyrocytes. Moreover, we show that thyroid cancers exhibit alterations in FOXO transcription besides the previously reported alterations in posttranslational FOXO3 regulation. These findings may add to the concept of targeting the PI3K pathway in advanced thyroid cancers.
  • van Dijk, Jacintha G. B., et al. (författare)
  • A Comparative Study of the Innate Humoral Immune Response to Avian Influenza Virus in Wild and Domestic Mallards
  • 2020
  • Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X .- 1664-302X. ; 11, s. 1-13
  • Tidskriftsartikel (refereegranskat)abstract
    • Domestic mallards (Anas platyrhynchos domesticus) are traditionally used as a model to investigate infection dynamics and immune responses to low pathogenic avian influenza viruses (LPAIVs) in free-living mallards. However, it is unclear whether the immune response of domestic birds reflects the response of their free-living counterparts naturally exposed to these viruses. We investigated the extent to which the innate humoral immune response was similar among (i) wild-type domestic mallards in primary and secondary infection with LPAIV H4N6 in a laboratory setting (laboratory mallards), (ii) wild-type domestic mallards naturally exposed to LPAIVs in a semi-natural setting (sentinel mallards), and (iii) free-living mallards naturally exposed to LPAIVs. We quantified innate humoral immune function by measuring non-specific natural antibodies (agglutination), complement activity (lysis), and the acute phase protein haptoglobin. We demonstrate that complement activity in the first 3 days after LPAIV exposure was higher in primary-exposed laboratory mallards than in sentinel and free-living mallards. LPAIV H4N6 likely activated the complement system and the acute phase response in primary-exposed laboratory mallards, as lysis was higher and haptoglobin lower at day 3 and 7 post-exposure compared to baseline immune function measured prior to exposure. There were no differences observed in natural antibody and haptoglobin concentrations among laboratory, sentinel, and free-living mallards in the first 3 days after LPAIV exposure. Our study demonstrates that, based on the three innate humoral immune parameters measured, domestic mallards seem an appropriate model to investigate innate immunology of their free-living counterparts, albeit the innate immune response of secondary-LPAIV exposed mallards is a better proxy for the innate immune response in pre-exposed free-living mallards than that of immunologically naive mallards.
  • Lesch, Christine, et al. (författare)
  • A role for Hemolectin in coagulation and immunity in Drosophila melanogaster
  • 2007
  • Ingår i: Developmental and Comparative Immunology. - : Elsevier BV. - 0145-305X .- 1879-0089. ; 31:12, s. 1255-1263
  • Tidskriftsartikel (refereegranskat)abstract
    • Hemolectin has been identified as a candidate clotting factor in Drosophila. We reassessed the domain structure of Hemolectin (Hml) and propose that instead of C-type lectin domains, the two discoidin domains are most likely responsible for the protein's lectin activity. We also tested Hml's role in coagulation and immunity in Drosophila. Here we describe the isolation of a new hml allele in a forward screen for coagulation mutants, and our characterization of this and two other hml alleles, one of which is a functional null. While loss of Hml had strong effects on larval hemolymph coagulation ex vivo, mutant larvae survived wounding. Drosophila thus possesses redundant hemostatic mechanisms. We also found that loss of Hml in immune-handicapped adults rendered them more sensitive to Gram(-) bacteria infection. This demonstrates an immunological role of this clotting protein and reinforces the importance of the clot in insect immunity.
  • Kalbina, Irina, 1961-, et al. (författare)
  • Arabidopsis thaliana plants expressing Rift Valley fever virus antigens : Mice exhibit systemic immune responses as the result of oraladministration of the transgenic plants
  • 2016
  • Ingår i: Protein Expression and Purification. - San Diego, USA : Elsevier. - 1046-5928 .- 1096-0279. ; 127, s. 61-67
  • Tidskriftsartikel (refereegranskat)abstract
    • The zoonotic Rift Valley fever virus affects livestock and humans in Africa and on the Arabian Peninsula.The economic impact of this pathogen due to livestock losses, as well as its relevance to public health,underscores the importance of developing effective and easily distributed vaccines. Vaccines that can bedelivered orally are of particular interest.Here, we report the expression in transformed plants (Arabidopsis thaliana) of Rift Valley fever virusantigens. The antigens used in this study were the N protein and a deletion mutant of the Gn glycoprotein.Transformed lines were analysed for specific mRNA and protein content by RT-PCR and Westernblotting, respectively. Furthermore, the plant-expressed antigens were evaluated for their immunogenicityin mice fed the transgenic plants. After oral intake of fresh transgenic plant material, a proportionof the mice elicited specific IgG antibody responses, as compared to the control animals that were fedwild-type plants and of which none sero-converted.Thus, we show that transgenic plants can be readily used to express and produce Rift Valley Fever virusproteins, and that the plants are immunogenic when given orally to mice. These are promising findingsand provide a basis for further studies on edible plant vaccines against the Rift Valley fever virus.
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