| 1. |
- Petursdottir, Dagbjort H., et al.
(författare)
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Early-Life Human Microbiota Associated With Childhood Allergy Promotes the T Helper 17 Axis in Mice
- 2017
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The intestinal microbiota influences immune maturation during childhood, and is implicated in early-life allergy development. However, to directly study intestinal microbes and gut immune responses in infants is difficult. To investigate how different types of early-life gut microbiota affect immune development, we collected fecal samples from children with different allergic heredity (AH) and inoculated germ-free mice. Immune responses and microbiota composition were evaluated in the offspring of these mice. Microbial composition in the small intestine, the cecum and the colon were determined by 16S rRNA sequencing. The intestinal microbiota differed markedly between the groups of mice, but only exposure to microbiota associated with AH and known future allergy in children resulted in a T helper 17 (Th17)-signature, both systemically and in the gut mucosa in the mouse offspring. These Th17 responses could be signs of a particular microbiota and a shift in immune development, ultimately resulting in an increased risk of allergy.
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| 2. |
- Albrecht, Eva, et al.
(författare)
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Telomere length in circulating leukocytes is associated with lung function and disease
- 2014
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 43:4, s. 983-992
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Tidskriftsartikel (refereegranskat)abstract
- Several clinical studies suggest the involvement of premature ageing processes in chronic obstructive pulmonary disease (COPD). Using an epidemiological approach, we studied whether accelerated ageing indicated by telomere length, a marker of biological age, is associated with COPD and asthma, and whether intrinsic age-related processes contribute to the interindividual variability of lung function. Our meta-analysis of 14 studies included 934 COPD cases with 15 846 controls defined according to the Global Lungs Initiative (GLI) criteria (or 1189 COPD cases according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria), 2834 asthma cases with 28 195 controls, and spirometric parameters (forced expiratory volume in is (FEV1), forced vital capacity (PVC) and FEV1/FVC) of 12 595 individuals. Associations with telomere length were tested by linear regression, adjusting for age, sex and smoking status. We observed negative associations between telomere length and asthma (beta= -0.0452, p= 0.024) as well as COPD (beta= -0.0982, p=0.001), with associations being stronger and more significant when using GLI criteria than those of GOLD. In both diseases, effects were stronger in females than males. The investigation of spirometric indices showed positive associations between telomere length and FEV1 (p=1.07 x 10(-7)), FVC (p=2.07 x 10(-5)), and FEV1/FVC (p =5.27 x 10(-3)). The effect was somewhat weaker in apparently healthy subjects than in COPD or asthma patients. Our results provide indirect evidence for the hypothesis that cellular senescence may contribute to the pathogenesis of COPD and asthma, and that lung function may reflect biological ageing primarily due to intrinsic processes, which are likely to be aggravated in lung diseases.
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| 3. |
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| 4. |
- Björkander, Sophia, et al.
(författare)
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Staphylococcus aureus-derived factors induce IL-10, IFN-gamma and IL-17A-expressing FOXP3(+)CD161(+) T-helper cells in a partly monocyte-dependent manner
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus aureus (S. aureus) is a human pathogen as well as a frequent colonizer of skin and mucosa. This bacterium potently activates conventional T-cells through superantigens and it is suggested to induce T-cell cytokine-production as well as to promote a regulatory phenotype in T-cells in order to avoid clearance. This study aimed to investigate how S. aureus impacts the production of regulatory and pro-inflammatory cytokines and the expression of CD161 and HELIOS by peripheral CD4(+)FOXP3(+) T-cells. Stimulation of PBMC with S. aureus 161:2-cell free supernatant (CFS) induced expression of IL-10, IFN-gamma and IL-17A in FOXP3(+) cells. Further, CD161 and HELIOS separated the FOXP3(+) cells into four distinct populations regarding cytokine-expression. Monocyte-depletion decreased S. aureus 161:2-induced activation of FOXP3(+) cells while pre-stimulation of purified monocytes with S. aureus 161:2-CFS and subsequent co-culture with autologous monocyte-depleted PBMC was sufficient to mediate activation of FOXP3(+) cells. Together, these data show that S. aureus potently induces FOXP3(+) cells and promotes a diverse phenotype with expression of regulatory and pro-inflammatory cytokines connected to increased CD161-expression. This could indicate potent regulation or a contribution of FOXP3(+) cells to inflammation and repression of immune-suppression upon encounter with S. aureus.
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| 5. |
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| 6. |
- Hell, Anna, et al.
(författare)
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Young L2-learners' meaning-making in engaging in computer-assisted language learning
- 2021
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Ingår i: The EUROCALL Review. - : The European Association for Computer Assisted Language Learning. - 1695-2618. ; 29:1, s. 2-18
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Tidskriftsartikel (refereegranskat)abstract
- This study explores how newly arrived young students created meaning, communicated, and expressed themselves using digital technology in the subject of Swedish as a second language (SSL). The qualitative case study presented in this article focuses on how the orchestration of teaching contributed to opportunities for digital meaning-making in the SSL subject in four classrooms at three schools in a city in Sweden. The notion of language as being fluid, which involves a critical approach to languages as separable entities, considers linguistic and embodied meaning-making, including digital technology, in social processes. This approach recognizes the roles of technology and digital meaning-making in young students’ second language acquisition. Moreover, technological innovations facilitate immediate and accessible communication. In today’s language studies, ethnicity only is not considered an adequate focus of analysis. Furthermore, the meaning-making practices of newly arrived primary school-aged students remain under-investigated. In the present study, data collected in classroom observations and teacher interviews revealed three themes regarding the students’ utilization of digital technology to develop their multilingual skills. One insight was that the newly arrived students used digital technology strategically when they engaged in meaning-making activities with peers and teachers. When the students took the initiative in computer-assisted language learning, they displayed agency in meaning-making by being their own architects. The findings of this research provided insights into how the orchestration of teaching in Swedish as a second language to newly arrived students affects their opportunities to use multilingualism in meaning-making while employing digital technology.
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| 7. |
- Hell, Eva
(författare)
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Studies on Staphylococcus epidermidis biofilm formation and the bacterial interaction with the human cathelicidin antimicrobial peptide LL-37
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The long-term use of central venous catheters for delivering nutrients and drugs in preterm neonates has been related to nosocomial infections. The majority of late-onset sepsis in very preterm infants (<28 gestational weeks) are caused by Gram positive bacteria. Coagulase- negative staphylococci (CoNS) are responsible for almost the half of these cases. Staphylococcus epidermidis is the most prevalent bacteria identified from CoNS bacteraemia and biofilm production is found to be the main determinant of persistent infection. The major host defense peptide LL-37 is the only cathelicidin antimicrobial peptide that exists in humans. The peptide is broadly distributed in the human body and possesses several additional functions related to host defense. As a cathionic peptide, it interacts with the negatively charged bacterial surface. LL-37 is shown to inhibit biofilm formation and regulates biofilm-associated gene expression in Pseudomonas aeruginosa in vitro. In Paper I, we showed that S. epidermidis strains obtained from bloodstream infection in preterm infants had different characteristics than the skin strains isolated from healthy term neonates. The blood isolates were equipped with an invasive genetic element IS256 and showed higher antimicrobial resistance compared with the skin isolates. However, vancomycin resistance was not detected among any of the strains. We also observed short and long filament- like structures on the cell surface of S. epidermidis. These filaments were involved in the attachment to the catheter surface and also in cell to cell attachment and/or communication. Our in vitro studies in Paper II and Paper III, revealed that physiological LL-37 peptide concentrations, below those that kill or inhibit growth of the free-floating bacteria, inhibited S. epidermidis attachment and biofilm formation on abiotic surfaces. In Paper III, we observed that the peptide regulates genes involved in the biofilm formation. In Paper IV, we found that the circulating serum level of hCAP18/LL-37 was similar in preterm and term neonates at birth and both the inactive protein and the active peptide were detectable independent of the gestational time. We observed positive correlation between maternal and infant peptide concentration. This may indicate that the peptide passes over early during pregnancy. In summary, our work revealed that S. epidermidis strains that cause bloodstream infection in preterm infants are more virulent compared with skin strains in term neonates. Physiological concentration of the human cathionic peptide LL-37 had inhibitory effect on S. epidermidis biofilm formation by regulating biofilm genes. The similar LL-37 peptide concentration in preterm and term infants’ blood might suggest that these neonate’s vulnerability is not connected to the lower antimicrobial peptide level at birth.
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| 8. |
- Nelson, Annika, et al.
(författare)
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Staphylococcus epidermidis Isolated From Newborn Infants Express Pilus-Like Structures and Are Inhibited by the Cathelicidin-Derived Antimicrobial Peptide LL37
- 2009
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Ingår i: Pediatric Research. - 0031-3998 .- 1530-0447. ; 66:2, s. 174-178
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Tidskriftsartikel (refereegranskat)abstract
- Coagulase-negative staphylococci and its subtype Staphylococcus epidermidis are major indigenous Gram-positive inhabitants of the human skin. Colonization occurs in direct connection with birth and terrestrial adaptation. This study focuses on factors that may influence skin colonization of the newborn infant that relates to the immune status of both the bacteria and the host. Skin is an effective barrier against bacteria, and this function is partly mediated by the presence of antimicrobial peptides including human cathelicidin peptide LL37. Grain-positive bacteria have been described to have adhesive pili on their surface that mediates specific attachment to the host. Here, we identify, by negative staining transmission electron microscopy (EM), two different types of pilus-like structures commonly expressed on S. epidermidis isolated from newborn infants. We also show that the cathelicidin antimicrobial peptide LL37, constitutively expressed in the skin barrier of the newborn, significantly inhibited growth of S. epidermidis indicating its importance for the ecological stability of the skin microbiota. Further studies are required to elucidate molecular mechanisms of host-microbe interactions, both for the maintenance of a mutually beneficial homeostatic relationship and for the protection of self when it results in overt disease. (Pediatr Res 66: 174-178, 2009)
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| 9. |
- Ogonowski, Martin, et al.
(författare)
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Evidence for selective bacterial community structuring on microplastics
- 2018
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912 .- 1462-2920. ; 20:8, s. 2796-2808
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Tidskriftsartikel (refereegranskat)abstract
- In aquatic ecosystems, microplastics are a relatively new anthropogenic substrate that can readily be colonized by biofilm-forming organisms. To examine the effects of substrate type on microbial community assembly, we exposed ambient Baltic bacterioplankton to plastic substrates commonly found in marine environments (polyethylene, polypropylene and polystyrene) as well as native (cellulose) and inert (glass beads) particles for 2 weeks under controlled conditions. The source microbial communities and those of the biofilms were analyzed by Illumina sequencing of the 16S rRNA gene libraries. All biofilm communities displayed lower diversity and evenness compared with the source community, suggesting substrate-driven selection. Moreover, the plastics-associated communities were distinctly different from those on the non-plastic substrates. Whereas plastics hosted greater than twofold higher abundance of Burkholderiales, the non-plastic substrates had a significantly higher proportion of Actinobacteria and Cytophagia. Variation in the community structure, but not the cell abundance, across the treatments was strongly linked to the substrate hydrophobicity. Thus, microplastics host distinct bacterial communities, at least during early successional stages.
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| 10. |
- Richter, Katharina N., et al.
(författare)
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Glyoxal as an alternative fixative to formaldehyde in immunostaining and super-resolution microscopy
- 2018
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Ingår i: EMBO Journal. - : WILEY. - 0261-4189 .- 1460-2075. ; 37:1, s. 139-159
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Tidskriftsartikel (refereegranskat)abstract
- Paraformaldehyde (PFA) is the most commonly used fixative for immunostaining of cells, but has been associated with various problems, ranging from loss of antigenicity to changes in morphology during fixation. We show here that the small dialdehyde glyoxal can successfully replace PFA. Despite being less toxic than PFA, and, as most aldehydes, likely usable as a fixative, glyoxal has not yet been systematically tried in modern fluorescence microscopy. Here, we tested and optimized glyoxal fixation and surprisingly found it to be more efficient than PFA-based protocols. Glyoxal acted faster than PFA, cross-linked proteins more effectively, and improved the preservation of cellular morphology. We validated glyoxal fixation in multiple laboratories against different PFA-based protocols and confirmed that it enabled better immunostainings for a majority of the targets. Our data therefore support that glyoxal can be a valuable alternative to PFA for immunostaining.
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