| 1. |
- Pihl, Maria, et al.
(författare)
-
Effects of clinical isolates of Pseudomonas aeruginosa on Staphylococcus epidermidis biofilm formation
- 2010
-
Ingår i: FEMS Immunology and Medical Microbiology. - : Wiley-Blackwell. - 0928-8244 .- 1574-695X. ; 59:3, s. 504-512
-
Tidskriftsartikel (refereegranskat)abstract
- Pseudomonas aeruginosa is often found in chronic infections, including cystic fibrosis lung infections and those related to chronic wounds and venous ulcers. At the latter sites, P. aeruginosa can be isolated together with Staphylococcus epidermidis, and we have therefore explored the effect of clinical isolates and laboratory strains of P. aeruginosa strains on colonisation by S. epidermidis in dual-species biofilms. Biofilm formation was assayed using 16S rRNA fluorescence in situ hybridization and confocal laser scanning microscopy. Amongst the six P. aeruginosa strains tested, one particular strain, denoted 14:2, exerted a significant inhibitory effect and even after six hours, S. epidermidis levels in dual-species biofilms were reduced by more than 85% compared to biofilms without P. aeruginosa. Interestingly strain 14:2 was found to be negative for classical virulence determinants including pyocyanin, elastase and alkaline protease. Therefore, we suggest that less virulent phenotypes of P. aeruginosa which may develop over time in chronic infections, could counteract colonisation by S. epidermidis, ensuring persistence and dominance by P. aeruginosa in the host micro-habitat. Further studies are required to explain the inhibitory effect on S. epidermidis, although, extracellular polysaccharides produced by P. aeruginosa might play a role in this phenomenon.
|
|
| 2. |
- Andersson, C., et al.
(författare)
-
Protection against respiratory syncytial virus (RSV) elicited in mice by plasmid DNA immunisation encoding a secreted RSV G protein-derived antigen
- 2000
-
Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 29:4, s. 247-253
-
Tidskriftsartikel (refereegranskat)abstract
- Plasmid vectors encoding two different variants, one cytoplasmic and one secreted version, of a candidate vaccine BBG2Na to respiratory syncytial virus (RSV), were constructed and evaluated in a nucleic acid vaccination study. The two different vectors, which employed the Semliki Forest virus gene amplification system, were found to express BBG2Na appropriately in in vitro cell cultures. Immunisation of mice with the plasmid vectors elicited significant serum anti-BBG2Na IgG responses only in the mice receiving the plasmid encoding the secreted version of BBG2Na. Consistent with antibody induction data, sterilising lung protection against RSV-A challenge was also only observed in this group. These results indicate that the targeting of antigen expression (intracellular versus secreted) would be an important factor to consider in the design of nucleic acid vaccines.
|
|
| 3. |
- Strindhall, Jan, et al.
(författare)
-
Variations among clinical isolates of Staphylococcus aureus to induce expression of E-selectin and ICAM-1 in human endothelial cells
- 2002
-
Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 32:3, s. 227-235
-
Tidskriftsartikel (refereegranskat)abstract
- Eighteen clinical isolates of Staphylococcus aureus, nine methicillin-sensitive and nine methicillin-resistant, were investigated for their ability to induce expression of E-selectin and ICAM-1 in human endothelial cells. Upregulation of adhesion molecules varied between isolates; 17 isolates induced expression of E-selectin and 13 of ICAM-1. Some isolates induced a significant expression of E-selectin without stimulation of ICAM-1, whereas the opposite was not found. Bacterial viability was required for induction of the adhesion molecules. The kinetics of ICAM-1 expression in S. aureus-infected cells differed from those stimulated with interleukin-1β (IL-1β). On the other hand, expression of E-selectin was very similar in S. aureus-infected and IL-1β-stimulated cells. There was no correlation between ability of S. aureus to induce expression of cell adhesion molecules, methicillin susceptibility, pulse field gel electrophoresis patterns, biochemical characteristics, phage typing and toxin production.
|
|
| 4. |
- Schöier, Johan, et al.
(författare)
-
Chlamydia (Chlamydophila) pneumoniae-induced cell death in human coronary artery endothelial cells is caspase-independent and accompanied by subcellular translocations of Bax and apoptosis-inducing factor.
- 2006
-
Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 47:2, s. 207-216
-
Tidskriftsartikel (refereegranskat)abstract
- Atherosclerosis and coronary heart disease are causing high morbidity and mortality worldwide. Different risk factors have been demonstrated, but the exact mechanisms behind these diseases are still not fully understood. Recent studies have suggested Chlamydia pneumoniae to be involved in the pathogenesis, and increased apoptotic indexes in atherosclerotic plaques have been documented. In this study, we show that C. pneumoniae induces apoptosis and necrosis in populations of human coronary artery endothelial cells. Apoptosis was determined by TUNEL and flow cytometry after staining of cells with annexin V and propidium iodide, and defined as TUNEL-reactive or annexin V-positive, propidium iodide-negative cells. The apoptosis was induced within 2 h postinfection and increased with inoculation dose. The general caspase inhibitor z-VAD-fmk did not affect apoptotic frequencies. By immunochemistry and immunoblot, we demonstrated activation and subcellular translocation of the proapoptotic protein Bax, and translocation of apoptosis-inducing factor from the cytosol to the nucleus. These results indicate that C. pneumoniae-induced apoptosis in human coronary artery endothelial cells is caspase-independent and regulated by Bax and apoptosis-inducing factor.
|
|
| 5. |
- Bjarnsholt, Thomas, et al.
(författare)
-
Understanding biofilms : are we there yet?
- 2012
-
Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 65:2, s. 125-126
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
- Eberhard, Thomas, et al.
(författare)
-
Interaction of vitronectin with Haemophilus influenzae
- 2002
-
Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 34:3, s. 215-219
-
Tidskriftsartikel (refereegranskat)abstract
- Eight strains of Haemophilus influenzae were tested for binding to human vitronectin. All strains adhered to vitronectin-coated glass slides but no binding was detected using soluble vitronectin, suggesting that surface association of vitronectin is a prerequisite. Vitronectin binding was not likely to be mediated by fimbriae as non-fimbriated and fimbriated isogenic strains adhered equally. Adhesion could be blocked by heparin, which is also known to block vitronectin binding to Staphylococcus aureus. However, no blocking was achieved with sialic acid-rich glycoproteins such as fetuin and mucin contrasting with Helicobacter pylori for which sialic acid seems to play an important role. With Streptococcus pneumoniae binding was detected both with soluble and surface-associated vitronectin and could not be blocked by heparin. Our results suggest that H. influenzae, Streptococcus pneumoniae and Helicobacter pylori all use distinct modes to interact with vitronectin.
|
|
| 7. |
- Engström, Patrik, 1982-, et al.
(författare)
-
A comparative study of RNA and DNA as internal gene expression controls early in the developmental cycle of Chlamydia pneumoniae
- 2010
-
Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 58:2, s. 244-253
-
Tidskriftsartikel (refereegranskat)abstract
- Many microbial pathogens invade and proliferate within host cells and the molecular mechanism underlying this behavior is currently being revealed for several bacterial species. Testing clinically relevant antibacterial compounds and elucidating their effects on gene expression requires adequate controls, especially when studying genetically intractable organisms such as Chlamydia spp., for which various gene fusions cannot be constructed. Until now, relative mRNA levels in Chlamydia have been measured using different internal gene expression controls, including 16S rRNA, mRNAs, and DNA. Here, we compared the advantages and disadvantages of various internal expression controls during the early phase of Chlamydia pneumoniae development. The relative abundance of target mRNAs varied using the different internal control RNAs. This was partly due to variation in the transcript stability of the RNA species. Also, seven out of nine of the analyzed RNAs increased fivefold or more between 2 and 14 h postinfection, while the amount of DNA and number of cells remained essentially unaltered. Our results suggest that RNA should not be used as a gene expression control during the early phase of Chlamydia development, and that intrinsic bacterial DNA is preferable for that purpose because it is stable, abundant, and its relative amount is generally correlated with bacterial numbers.
|
|
| 8. |
|
|
| 9. |
- Karlsson, Mattias, 1981-, et al.
(författare)
-
Substances released from probiotic Lactobacillus rhamnosus GR-1 potentiate NF-κB activity in Escherichia coli-stimulated urinary bladder cells
- 2012
-
Ingår i: FEMS Immunology and Medical Microbiology. - Hoboken, USA : Wiley-Blackwell. - 0928-8244 .- 1574-695X. ; 66:2, s. 147-156
-
Tidskriftsartikel (refereegranskat)abstract
- Lactobacillus rhamnosus GR-1 is a probiotic bacterium used to maintain urogenital health. The putative mechanism for its probiotic effect is by modulating the host immunity. Urinary tract infections (UTI) are often caused by uropathogenic Escherichia coli that frequently evade or suppress immune responses in the bladder and can target pathways, including nuclear factor-kappaB (NF-κB). We evaluated the role of L. rhamnosus GR-1 on NF-κB activation in E. coli-stimulated bladder cells. Viable L. rhamnosus GR-1 was found to potentiate NF-κB activity in E. coli-stimulated T24 bladder cells, whereas heat-killed lactobacilli demonstrated a marginal increase in NF-κB activity. Surface components released by trypsin- or LiCl treatment, or the resultant heat-killed shaved lactobacilli, had no effect on NF-κB activity. Isolation of released products from L. rhamnosus GR-1 demonstrated that the induction of NF-κB activity was owing to released product(s) with a relatively large native size. Several putative immunomodulatory proteins were identified, namely GroEL, elongation factor Tu and NLP/P60. GroEL and elongation factor Tu have previously been shown to elicit immune responses from human cells. Isolating and using immune-augmenting substances produced by lactobacilli is a novel strategy for the prevention or treatment of UTI caused by immune-evading E. coli.
|
|
| 10. |
- Maripuu, Linda, et al.
(författare)
-
Superantigen gene profile diversity among clinical group A streptococcal isolates.
- 2008
-
Ingår i: FEMS Immunology and Medical Microbiology. - 0928-8244 .- 1574-695X. ; 54:2, s. 236-44
-
Tidskriftsartikel (refereegranskat)abstract
- This study examines the diversity of superantigen gene profiles between and within emm-genotypes of 92 clinical group A streptococcal isolates (30 STSS, 24 sepsis, 25 erysipelas, and 12 tonsillitis) collected in Sweden between 1986 and 2001. The emm-genotype and the distribution of smeZ, speG, speJ, speA, speC, speH, speI, speK/L, speL/M, speM, and ssa genes, and the smeZ allelic variant were determined using PCR and DNA sequencing. Forty-five emm1 isolates revealed 10 superantigen gene profiles. One profile dominated and was identified in 22 isolates collected over 14 years. The results indicate that a selective advantage maintained this genotype in circulation. The superantigen content among the emm1 isolates ranged from three to seven, with smeZ-1, speG, and speA present in all but one profile. The 47 isolates of 27 other emm-genotypes exhibited 29 superantigen gene profiles. Thus, the distribution of superantigen genes was highly variable within isolates regardless of emm-genotype. Two novel emm1 subtypes and 14 novel smeZ allelic variants were identified. The 22 smeZ alleles were generally linked to the emm-genotype. The results of the investigation show that superantigen gene profiling is useful for tracking spread of clones in the community.
|
|
