| 1. |
- Bjerketorp, Joakim, et al.
(author)
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Antibacterial 3,6-Disubstituted 4-Hydroxy-5,6-dihydro-2H-pyran-2-ones from Serratia plymuthica MF371-2
- 2017
-
In: Journal of natural products (Print). - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 80:11, s. 2997-3002
-
Journal article (peer-reviewed)abstract
- Bioassay-guided fractionation of culture extracts of Serratia plymuthica strain MF371-2 resulted in the isolation of two new antibacterial compounds with potent activity against Gram-positive bacteria, including Staphylococcus aureus LMG 15975 (MRSA). A spectroscopic investigation, in combination with synthesis, enabled the characterization of the compounds as 3-butyryl-4-hydroxy-6-heptyl-5,6-dihydro2H-pyran-2-one (plymuthipyranone A, 1) and 3-butyry1-4-hydroxy-6-nony1-5,6-dihydro-2H-pyran-2-one (plymuthipyranone B, 2). The MIC values for 1 and 2 against S. aureus LMG 15975 were determined to be 1-2 mu g mL(-1) and 0.8 mu g mL(-1), respectively. Compound 2 was found to have potent activity against many strains of S. aureus, including several mupirocin-resistant strains, other species of Staphylococcus, and vancomycin-resistant enterococci. Compound 2 was slightly cytotoxic for human cells, with CC50 values between 4.7 and 40 mu g mL(-1), but the CC50/MIC ratio was >= 10 for many tested combinations of human cells and bacteria, suggesting its possible use as an antibacterial agent. Several analogues were synthesized with different alkyl groups in the 3- and 6-positions (6-13), and their biological properties were evaluated. It was concluded that the activity of the compounds increased with the lengths of the alkyl and acyl substituents.
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| 2. |
- Bjerketorp, Joakim, et al.
(author)
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Selective Isolation of Multidrug-Resistant Pedobacter spp., Producers of Novel Antibacterial Peptides
- 2021
-
In: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 12
-
Journal article (peer-reviewed)abstract
- Twenty-eight multidrug-resistant bacterial strains closely related or identical to Pedobacter cryoconitis, Pedobacter lusitanus and Pedobacter steynii were isolated from soil samples by selection for multidrug-resistance. Approximately 3-30% of the selected isolates were identified as Pedobacter, whereas isolation without antibiotics did not yield any isolates of this genus. Next generation sequencing data showed Pedobacter to be on 69th place among the bacterial genera (0.32% of bacterial sequences). The Pedobacter isolates produced a wide array of novel compounds when screened by UHPLC-MS/MSMS, and hierarchical cluster analysis resulted in several distinct clusters of compounds produced by specific isolates of Pedobacter, and most of these compounds were found to be peptides. The Pedobacter strain UP508 produced isopedopeptins, whereas another set of strains produced pedopeptins, which both are known cyclic lipodepsipeptides produced by Pedobacter sp. Other Pedobacter strains produced analogous peptides with a sequence variation. Further strains of Pedobacter produced additional novel antibacterial cyclic lipopeptides (ca 800 or 1400 Da in size) and/or linear lipopeptides (ca 700-960 Da in size). A 16S rRNA phylogenetic tree for the Pedobacter isolates revealed several distinct clades and subclades of isolates. One of the subclades comprised isolates producing isopedopeptin analogs, but the isopedopeptin producing isolate UP508 was clearly placed on a separate branch. We suggest that the non-ribosomal peptide synthases producing pedopeptins, isopedopeptins, and the analogous peptides, may derive from a common ancestral non-ribosomal peptide synthase gene cluster, which may have been subjected to a mutation leading to changed specificity in one of the modules and then to a modular rearrangement leading to the changed sequence found in the isopedopeptins produced by isolate UP508.
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| 3. |
- Broberg, Anders, et al.
(author)
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In-peptide amino acid racemization via inter-residue oxazoline intermediates during acidic hydrolysis
- 2021
-
In: Amino Acids. - : Springer Nature. - 0939-4451 .- 1438-2199. ; 53:3, s. 323-331
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Journal article (peer-reviewed)abstract
- Isopedopeptins are antibiotic cyclic lipodepsipeptides containing the subsequence L-Thr-L-2,3-diaminopropanoic acid-D-Phe-L-Val/L-3-hydroxyvaline. Acidic hydrolysis of isopedopeptins in D2O showed the D-Phe residues to racemize extensively in peptides with L-3-hydroxyvaline but not in peptides with L-Val. Similarly, one Leu residue in pedopeptins, which are related peptides containing the subsequence Leu-2,3-diaminopropanoic acid-Leu-L-Val/L-3-hydroxyvaline, was found to racemize in peptides with L-3-hydroxyvaline. Model tetrapeptides, L-Ala-L-Phe-L-Val/3-hydroxyvaline-L-Ala, gave the corresponding results, i.e. racemization of L-Phe only when linked to a L-3-hydroxyvaline. We propose the racemization to proceed via an oxazoline intermediate involving Phe/Leu and the L-3-hydroxyvaline residues. The 3-hydroxyvaline residue may form a stable tertiary carbocation by loss of the sidechain hydroxyl group as water after protonation. Elimination of the Phe/Leu H-2 and ring-closure from the carbonyl oxygen onto the carbocation results in the suggested oxazoline intermediate. The reversed reaction leads to either retained or inversed configuration of Phe/Leu. Such racemization during acidic hydrolysis may occur whenever a 3-hydroxyvaline residue or any amino acid that can form a stable carbocation on the C-3, is present in a peptide. The proposed mechanism for racemization was supported by incorporation of O-18 in the 3-hydroxyvaline sidechain when the acidic hydrolysis was performed in H2O/(H2O)-O-18 (1:1). The 2,3-diaminopropanoic residues of isopedopeptins and pedopeptins were also found to racemize during acidic hydrolysis, as previously described. Based on the results, the configuration of the Leu and 2,3-diaminopropanoic acid residues of the pedopeptins were reassigned to be L-Leu and D-Leu, and 2 x L-2,3-diaminopropanoic acid.
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| 4. |
- Faroldi, Gianni, et al.
(author)
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ADAMTS: Novel proteases expressed by activated mast cells
- 2013
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In: Biological Chemistry. - : Walter de Gruyter GmbH. - 1431-6730 .- 1437-4315. ; 394, s. 291-305
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Journal article (peer-reviewed)abstract
- Here we show that mast cells (MCs) express the metalloproteases of the A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family, and that ADAMTS expression is influenced by MC activation. Co-culture of MCs with live Gram-positive bacteria caused a profound induction of ADAMTS-9 and -6, as well as down-regulated expression of ADAMTS-5. Similar patterns were also seen after MC activation with calcium ionophore and by immunoglobulin E receptor crosslinking. Moreover, ADAMTS-5, -6 and -9 were all induced by activation of terminally differentiated murine peritoneal MCs and in a human MC line. ADAMTS-9 up-regulation in response to immunoglobulin E receptor crosslinking was strongly dependent on Go6976-sensitive protein kinase C and partly dependent on nuclear factor of activated T cells and nuclear factor kappa-light-chain-enhancer of activated B cells, respectively. The expression of ADAMTS-5, -6 and -9 was closely linked to MC maturation, as shown by their strong induction during the differentiation of bone marrow precursor cells into mature MCs. ADAMTS family members have been shown to possess aggrecanase activity. Accordingly, MCs were shown to express aggrecanase activity. Finally, ADAMTS-5 protein was detected in MCs by immunocytochemistry. Taken together, the present study reveals ADAMTS expression by MCs and that MC activation regulates the expression of these proteases, thus implicating the ADAMTS family of proteases in MC function.
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| 5. |
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| 6. |
- Frosth, Sara, et al.
(author)
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Novel Genotype of Streptococcus dysgalactiae subsp. equisimilis Associated with Mastitis in an Arabian Filly: Genomic Approaches and Phenotypic Properties
- 2023
-
In: Journal of Equine Veterinary Science. - 0737-0806 .- 1542-7412. ; 130
-
Journal article (peer-reviewed)abstract
- Streptococcus dysgalactiae subsp. equisimilis (Sde) is a commensal bacterium of horses that causes opportunistic infections. The aim of the work was to study genotypic and phenotypic properties of the Sde strain related to equine neonatal mastitis. Sde was isolated from an 8 day-old filly and sequenced for genome analysis, antibiotic susceptibility tests and virulence factor (VF) assays. The Sde strain presented the novel emmsubtype stC839.12 and the novel multilocus-sequence type ST-670, which belonged to a specific equine genotype group. Although no specific genotypic mechanisms related to antibiotic resistance were found, it presented genes encoding efflux pumps and transporters pmrA, bmrC and lmrP. Genes encoding several putative VFs including emm, cpa, fbp-2, adcA , hyl, htrA , tig, slo, and ndk and loci encoding phosphoenolpyruvate-protein phosphotransferase systems were identified. This is the first report of an equine neonatal mastitis case caused by a novel genotype and horse specific Sde strain.(c) 2023 Elsevier Inc. All rights reserved.
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| 7. |
- Frykberg, Lars, et al.
(author)
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Antiphagocytic Function of an IgG Glycosyl Hydrolase from Streptococcus equi subsp equi and Its Use as a Vaccine Component
- 2012
-
In: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 80, s. 2914-2919
-
Journal article (peer-reviewed)abstract
- Endo Se from Streptococcus equi subsp. equi is an enzyme hydrolyzing glycosyl groups on IgG, analogous to EndoS from Streptococcus pyogenes. We here show that the activity of EndoSe leads to an antiphagocytic function and may thus be a contributory factor to immune evasion of S. equi. Despite the damaging effect that EndoSe has on IgG, antibodies against EndoSe can neutralize its function. Antibodies against EndoSe restored the opsonic activity of specific opsonizing antibodies. Mice infected with either S. equi subsp. equi or subsp. zooepidemicus or S. pyogenes could be protected by vaccination with EndoSe. It is speculated that EndoSe could be a suitable vaccine candidate against streptococcal infections.
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| 8. |
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| 9. |
- Guss, Bengt
(author)
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Integrin alpha(V)beta(3) can substitute for collagen-binding beta(1)-integrins in vivo to maintain a homeostatic interstitial fluid pressurel
- 2018
-
In: Experimental Physiology. - 0958-0670 .- 1469-445X. ; 103, s. 629-634
-
Journal article (peer-reviewed)abstract
- Accumulated data indicate that cell-mediated contraction of reconstituted collagenous gels in vitro can serve as a model for cell-mediated control of interstitial fluid pressure (P-IF) in vivo. A central role for collagen-binding beta(1)-integrins in both processes has been established. Furthermore, integrin alpha(V beta 3) takes over the role of collagen-binding beta(1)-integrins in mediating contraction after perturbations of collagen-binding beta(1)-integrins in vitro. Integrin alpha(V beta 3) is also instrumental for normalization of dermal P-IF that has been lowered due to mast cell degranulation with compound 48/80 (C48/80) in vivo. Here we demonstrate a role of integrin alpha(V)beta(3) in maintaining a long term homeostatic dermal P-IF in mice lacking the collagen-binding integrin alpha(111) (alpha 11(-/-) mice). Measurements of P-IF were performed after circulatory arrest. Furthermore, cell-mediated integrin alpha(V)beta(3)-directed contraction of collagenous gels in vitro depends on free access to a collagen site known to bind several extracellular matrix (ECM) proteins that form substrates for (V3)-directed cell attachment, such as fibronectin and fibrin. A streptococcal collagen-binding protein, CNE, specifically binds to and blocks this site on the collagen triple helix. Here we show that whereas CNE perturbed alpha(V beta 3)-directed and platelet-derived growth factor BB-induced normalization of dermal P-IF after C48/80, it did not affect alpha(V beta 3)-dependent maintenance of a homeostatic dermal P-IF. These data imply that dynamic modification of the ECM structure is needed during acute patho-physiological modulations of P-IF but not for long-term maintenance of a homeostatic P-IF. Our data thus show that collagen-binding beta(1)-integrins, integrin alpha(V)beta(3) and ECM structure are potential targets for novel therapy aimed at modulating oedema formation and hypovolemic shock during anaphylaxis.
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| 10. |
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| 11. |
- Hulting, Greta, et al.
(author)
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Two novel IgG endopeptidases of Streptococcus equi
- 2009
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In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 298:1, s. 44-50
-
Journal article (peer-reviewed)abstract
- Streptococcus equi ssp. equi causes strangles, a highly contagious and serious disease in the upper respiratory tract of horses. Streptococcus equi ssp. zooepidemicus, another subspecies of this genus, is regarded as an opportunistic commensal in horses. The present study describes the characterization of two novel immunoglobulin G (IgG) endopeptidases of these subspecies, IdeE2 and IdeZ2. Both enzymes display sequence similarities with two previously characterized IgG endopeptidases, IdeE of S. equi ssp. equi and IdeZ of S. equi ssp. zooepidemicus. IdeE2 and IdeZ2 display high substrate-specificity in comparison with IdeE and IdeZ, as they both completely cleave horse IgG, while the activity against IgG from mouse, rabbit, cat, cow, sheep and goat is low or absent. The potential use of IdeE and IdeE2 as vaccine components was studied in a mouse infection model. In this vaccination and challenge study, both enzymes induced protection against S. equi ssp. equi infection.
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| 12. |
- Johnzon, Carl-Fredrik, et al.
(author)
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Live Staphylococcus aureus Induces Expression and Release of Vascular Endothelial Growth Factor in Terminally Differentiated Mouse Mast Cells
- 2016
-
In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 7
-
Journal article (peer-reviewed)abstract
- Mast cells have been shown to express vascular endothelial growth factor (VEGF), thereby implicating mast cells in pro-angiogenic processes. However, the mechanism of VEGF induction in mast cells and the possible expression of VEGF in fully mature mast cells have not been extensively studied. Here, we report that terminally differentiated peritoneal cell-derived mast cells can be induced to express VEGF in response to challenge with Staphylococcus aureus, thus identifying a mast cell-bacteria axis as a novel mechanism leading to VEGF release. Whereas live bacteria produced a robust upregulation of VEGF in mast cells, heat-inactivated bacteria failed to do so, and bacteria-conditioned media did not induce VEGF expression. The induction of VEGF was not critically dependent on direct cell-cell contact between bacteria and mast cells. Hence, these findings suggest that VEGF can be induced by soluble factors released during the co-culture conditions. Neither of a panel of bacterial cell-wall products known to activate toll-like receptor (TLR) signaling promoted VEGF expression in mast cells. In agreement with the latter, VEGF induction occurred independently of Myd88, an adaptor molecule that mediates the downstream events following TLR engagement. The VEGF induction was insensitive to nuclear factor of activated T-cells inhibition but was partly dependent on the nuclear factor kappa light-chain enhancer of activated B cells signaling pathway. Together, these findings identify bacterial challenge as a novel mechanism by which VEGF is induced in mast cells.
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| 13. |
- Johnzon, Carl-Fredrik, et al.
(author)
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Mastitis Pathogens with high Virulence in a Mouse Model Produce a Distinct cytokine Profile In Vivo
- 2016
-
In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 7
-
Journal article (peer-reviewed)abstract
- Mastitis is a serious medical condition of dairy cattle. Here, we evaluated whether the degree of virulence of mastitis pathogens in a mouse model can be linked to the inflammatory response that they provoke. Clinical isolates of Staphylococcus aureus (S. aureus) (strain 556 and 392) and Escherichia coli (E. coli) (676 and 127), and laboratory control strains [8325-4 (S. aureus) and MG1655 (E. coli)], were injected i.p. into mice, followed by the assessment of clinical scores and inflammatory parameters. As judged by clinical scoring, E. coli 127 exhibited the largest degree of virulence among the strains. All bacterial strains induced neutrophil recruitment. However, whereas E. coli 127 induced high peritoneal levels of CXCL1, G-CSF, and CCL2, strikingly lower levels of these were induced by the less virulent bacterial strains. High concentrations of these compounds were also seen in blood samples taken from animals infected with E. coli 127, suggesting systemic inflammation. Moreover, the levels of CXCL1 and G-CSF, both in the peritoneal fluid and in plasma, correlated with clinical score. Together, these findings suggest that highly virulent clinical mastitis isolates produce a distinct cytokine profile that shows a close correlation with the severity of the bacterial infection.
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| 14. |
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| 15. |
- Levenfors, Jolanta, et al.
(author)
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Antibacterial pyrrolidinyl and piperidinyl substituted 2,4-diacetylphloroglucinols from Pseudomonas protegens UP46
- 2020
-
In: Journal of antibiotics (Tokyo. 1968). - : SPRINGERNATURE. - 0021-8820 .- 1881-1469. ; 73:11, s. 739-747
-
Journal article (peer-reviewed)abstract
- In the search for new antibiotic compounds, fractionation of Pseudomonas protegens UP46 culture extracts afforded several known Pseudomonas compounds, including 2,4-diacetylphloroglucinol (DAPG), as well as two new antibacterial alkaloids, 6-(pyrrolidin-2-yl)DAPG (1) and 6-(piperidin-2-yl)DAPG (2). The structures of 1 and 2 were determined by nuclear magnetic resonance spectroscopy and mass spectrometry. Compounds 1 and 2 were found to have antibacterial activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus cereus, with minimal inhibitory concentration (MIC) 2 and 4 mu g ml(-1), respectively, for 1, and 2 mu g ml(-1) for both pathogens for 2. The MICs for 1 and 2, against all tested Gram-negative bacteria, were >32 mu g ml(-1). The half maximal inhibitory concentrations against HepG2 cells for compounds 1 and 2 were 11 and 18 mu g ml(-1), respectively, which suggested 1 and 2 be too toxic for further evaluation as possible new antibacterial drugs. Stable isotope labelling experiments showed the pyrrolidinyl group of 1 to originate from ornithine and the piperidinyl group of 2 to originate from lysine. The P. protegens acetyl transferase (PpATase) is involved in the biosynthesis of monoacetylphloroglucinol and DAPG. No optical rotation was detected for 1 or 2, and a possible reason for this was investigated by studying if the PpATase may catalyse a stereo-non-specific introduction of the pyrrolidinyl/piperidinyl group in 1 and 2, but unless the PpATase can be subjected to major conformational changes, the enzyme cannot be involved in this reaction. The PpATase is, however, likely to catalyse the formation of 2,4,6-triacetylphloroglucinol from DAPG.
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| 16. |
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| 17. |
- Lidén, Åsa, et al.
(author)
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A fibronectin-binding protein from Streptococcus equi binds collagen and modulates cell-mediated collagen gel contraction
- 2006
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In: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 340:2, s. 604-610
-
Journal article (peer-reviewed)abstract
- The N-terminal fragment (FNZN) of the fibronectin-binding protein FNZ from Streptococcus equi subspecies zooepidemicus was investigated as to effects on murine cell interactions with extracellular matrix proteins. FNZN bound to immobilized fibronectin (FN) and native, but not denatured, collagen type I. FNZN had no effect on primary adhesion of cells from the murine myoblastic C2C12 cell line to immobilized fibronectin. C2C12 cells adhered to immobilized FNZN, a process that was not inhibited by anti-human FN IgG or by an inhibitor of integrin alphaVbeta3. C2C12 cells lack collagen-binding beta1 integrins and neither adhere to native collagen nor mediate contraction of three-dimensional collagen gels. FNZN stimulated collagen gel contraction by C2C12 cells but not adhesion of C2C12 cells to collagen. Experiments with an alphaVbeta3-inhibitor suggested that FNZN promoted contraction by a process requiring alphaVbeta3. Our data suggest that FNZN by binding to cells, collagen, and FN modulate complex adhesive processes mediated by the alphaVbeta3 integrin. Since alphaVbeta3-mediated contractile events function to counteract edema formation during inflammation, it is possible that FNZN and its secreted homologue FNE modulate edema responses in infected tissues.
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| 18. |
- Lidén, Åsa, et al.
(author)
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A secreted collagen- and fibronectin-binding streptococcal protein modulates cell-mediated collagen gel contraction and interstitial fluid pressure
- 2008
-
In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 283:3, s. 1234-1242
-
Journal article (peer-reviewed)abstract
- Fibroblast-mediated collagen gel contraction depends on collagen-binding beta1 integrins. Perturbation of these integrins reveals an alternative contraction process that is integrin alphaVbeta3-dependent and platelet-derived growth factor (PDGF) BB-stimulated. Connective tissue cells actively control interstitial fluid pressure (IFP), and inflammation-induced lowering of IFP provides a driving force for edema formation. PDGF-BB normalizes a lowered IFP by an alphaVbeta3-dependent process. A potential modulation of IFP by extracellular matrix-binding bacterial proteins has previously not been addressed. The fibronectin (FN)-binding protein FNE is specifically secreted by the highly virulent Streptococcus equi subspecies equi. FNE bound FN and native collagen type I with K(d) values of approximately 20 and approximately 50 nm determined by solid-phase binding assays. Rotary shadowing revealed a single FNE binding site located at on average 122 nm from the C terminus of procollagen type I. FNE induced alphaVbeta3-mediated contraction by C2C12 cells in a concentration-dependent manner having a maximal effect at approximately 100 nm. This activity of FNE required cellular FN, and FNE acted synergistically to added plasma FN or PDGF-BB. FNE enhanced binding of soluble FN to immobilized collagen, and conversely the binding of collagen to immobilized FN. Marked bell-shaped concentration dependences for these interactions suggest that FNE forms a bridge between FN and collagen. Finally, FNE normalized dermal IFP lowered by anaphylaxis. Our data suggest that secreted FNE normalized lowering of IFP by stimulating connective tissue cell contraction.
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| 19. |
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| 20. |
- Liden, Åsa, et al.
(author)
-
Integrin αVβ3 can substitute for collagen‐binding β1‐integrins in vivo to maintain a homeostatic interstitial fluid pressure
- 2018
-
In: Experimental Physiology. - 0958-0670 .- 1469-445X. ; 103:5, s. 629-634
-
Journal article (peer-reviewed)abstract
- Accumulated data indicate that cell‐mediated contraction of reconstituted collagenous gels in vitro can serve as a model for cell‐mediated control of interstitial fluid pressure (PIF) in vivo. A central role for collagen‐binding β1‐integrins in both processes has been established. Furthermore, integrin αVβ3 takes over the role of collagen‐binding β1‐integrins in mediating contraction after perturbations of collagen‐binding β1‐integrins in vitro. Integrin αVβ3 is also instrumental for normalization of dermal PIF that has been lowered due to mast cell degranulation with compound 48/80 (C48/80) in vivo. Here we demonstrate a role of integrin αVβ3 in maintaining a long term homeostatic dermal PIF in mice lacking the collagen‐binding integrin α11β1 (α11−/− mice). Measurements of PIF were performed after circulatory arrest. Furthermore, cell‐mediated integrin αVβ3‐directed contraction of collagenous gels in vitro depends on free access to a collagen site known to bind several extracellular matrix (ECM) proteins that form substrates for αVβ3‐directed cell attachment, such as fibronectin and fibrin. A streptococcal collagen‐binding protein, CNE, specifically binds to and blocks this site on the collagen triple helix. Here we show that whereas CNE perturbed αVβ3‐directed and platelet‐derived growth factor BB‐induced normalization of dermal PIF after C48/80, it did not affect αVβ3‐dependent maintenance of a homeostatic dermal PIF. These data imply that dynamic modification of the ECM structure is needed during acute patho‐physiological modulations of PIF but not for long‐term maintenance of a homeostatic PIF. Our data thus show that collagen‐binding β1‐integrins, integrin αVβ3 and ECM structure are potential targets for novel therapy aimed at modulating oedema formation and hypovolemic shock during anaphylaxis.
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| 21. |
- Nord, Christina, et al.
(author)
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Antibacterial Isoquinoline Alkaloids from the Fungus Penicillium Spathulatum Em19
- 2019
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In: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 24:24
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Journal article (peer-reviewed)abstract
- In the search for new microbial antibacterial secondary metabolites, two new compounds (1 and 2) were isolated from culture broths of Penicillium spathulatum Em19. Structure determination by nuclear magnetic resonance and mass spectrometry identified the compounds as 6,7-dihydroxy-5,10-dihydropyrrolo[1,2-b]isoquinoline-3-carboxylic acid (1, spathullin A) and 5,10-dihydropyrrolo[1,2-b]isoquinoline-6,7-diol (2, spathullin B). The two compounds displayed activity against both Gram-negative and -positive bacteria, including Escherichia coli, Acinetobacterbaumannii, Enterobactercloacae, Klebsiellapneumonia, Pseudomonasaeruginosa, and Staphylococcusaureus. Compound 2 was more potent than 1 against all tested pathogens, with minimal inhibitory concentrations down to 1 mu g/mL (5 mu M) against S. aureus, but 2 was also more cytotoxic than 1 (50% inhibitory concentrations 112 and 11 mu M for compounds 1 and 2, respectively, towards Huh7 cells). Based on stable isotope labelling experiments and a literature comparison, the biosynthesis of 1 was suggested to proceed from cysteine, tyrosine and methionine via a non-ribosomal peptides synthase like enzyme complex, whereas compound 2 was formed spontaneously from 1 by decarboxylation. Compound 1 was also easily oxidized to the 1,2-benzoquinone 3. Due to the instability of compound 1 and the toxicity of 2, the compounds are of low interest as possible future antibacterial drugs.
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| 22. |
- Nord, Christina, et al.
(author)
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Isopedopeptins A-H : Cationic Cyclic Lipodepsipeptides from Pedobacter cryoconitis UP508 Targeting WHO Top-Priority Carbapenem-Resistant Bacteria
- 2020
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In: ACS Chemical Biology. - : AMER CHEMICAL SOC. - 1554-8929 .- 1554-8937. ; 15:11, s. 2937-2944
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Journal article (peer-reviewed)abstract
- Pedobacter cryoconitis strain UP508 was isolated from a soil sample using a mixture of ampicillin, kanamycin, and nalidixic acid for selection. UP508 was found to produce >30 unknown antibacterial peptides, of which eight, isopedopeptins A-H (1-8), were isolated by bioassay-guided fractionation and characterized with respect to structures and biological properties. Compounds 1-8 were all composed of nine amino acid residues and one 3-hydroxy fatty acid residue, and the structures were ring-closed via an ester bond from the C-terminal aspartic acid to the 3-hydroxy fatty acid. The differences between the peptides were the size and branching of the 3-hydroxy fatty acid and the presence of a valine or a 3-hydroxyvaline residue. The isopedopeptins mainly had activity against Gram-negative bacteria, and isopedopeptin B (2), which had the best combination of antibacterial activity, in vitro cytotoxicity, and hemolytic properties, was selected for further studies against a larger panel of Gram-negative bacteria. Isopedopeptin B was found to have good activity against strains of WHO top-priority Gram-negative bacteria, i.e., carbapenem-resistant Acinetobacter baumannii, Escherichia coli, and Pseudomonas aeruginosa, with minimal inhibitory concentrations (MIC) down to 1, 2, and 4 mu g/mL, respectively. Furthermore, compound 2 had activity against colistin-resistant strains of A. baumannii, E. coli, and Klebsiella pneumoniae, with a MIC down to 8, 2, and 4 mu g/mL, respectively. Compound 6 was tested in an E. coli liposome system where it induced significant leakage, indicating membrane disruption as one mechanism involved in isopedopeptin antibacterial activity. Isopedopeptin B stands out as a promising candidate for further studies with the goal to develop a new antibiotic drug.
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| 23. |
- Nord, Christina, et al.
(author)
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Tetramic acid based alkaloids from Aspergillus amoenus Roberg strain UP197-antibiotic properties and new pyranterreones
- 2022
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In: Natural Product Research. - : Informa UK Limited. - 1478-6419 .- 1478-6427. ; 36:4, s. 967-973
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Journal article (peer-reviewed)abstract
- The fungus Aspergillus amoenus Roberg strain UP197 was shown to produce antibacterial tetramic acid based alkaloids. Two new compounds, pyranterreone I and J (1 and 2), were isolated and characterized, in addition to the known compounds cordylactam, 7-hydroxycordylactam, pyranterreone C, D, F and G. Neither the pyranterreones nor the cordylacctams had previously been tested for antimicrobial activity. Thus, all isolated compounds were tested against a panel of clinically important bacteria and fungi. Pyranterreone C was active against Gram-positive and Gram-negative bacteria, with minimal inhibitory concentrations (MIC) between 1 and 8 mu g/mL, whereas the MICs for all other compounds were >32 mu g/mL. Pyranoterreone C was cytotoxic towards HepG2 cells, and since pyranterreone C reacted rapidly with the nucleophile cysteine, it is likely that the observed antibacterial activity is due to the chemical reactivity rather than enzymatic affinity, making it unsuitable for development as an antibacterial drug.
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| 24. |
- Pringle, John, et al.
(author)
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Globetrotting strangles: the unbridled national and international transmission of Streptococcus equi between horses
- 2021
-
In: Microbial genomics. - : Microbiology Society. - 2057-5858. ; 7
-
Journal article (peer-reviewed)abstract
- The equine disease strangles, which is characterized by the formation of abscesses in the lymph nodes of the head and neck, is one of the most frequently diagnosed infectious diseases of horses around the world. The causal agent, Streptococcus equi subspecies equi, establishes a persistent infection in approximately 10 % of animals that recover from the acute disease. Such ?carrier? animals appear healthy and are rarely identified during routine veterinary examinations pre- purchase or transit, but can transmit S. equi to na?ve animals initiating new episodes of disease. Here, we report the analysis and visualization of phylogenomic and epidemiological data for 670 isolates of S. equi recovered from 19 different countries using a new core- genome multilocus sequence typing (cgMLST) web bioresource. Genetic relationships among all 670 S. equi isolates were determined at high resolution, revealing national and international transmission events that drive this endemic disease in horse populations throughout the world. Our data argue for the recognition of the international importance of strangles by the Office International des ?pizooties to highlight the health, welfare and economic cost of this disease. The Pathogenwatch cgMLST web bioresource described herein is available for tailored genomic analysis of populations of S. equi and its close relative S. equi subspecies zooepidemicus that are recovered from horses and other animals, including humans, throughout the world. This article contains data hosted by Microreact.
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| 25. |
- Reyhani, Vahid, et al.
(author)
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Fibrin binds to collagen and provides a bridge for alpha V beta 3 integrin-dependent contraction of collagen gels
- 2014
-
In: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 462, s. 113-123
-
Journal article (peer-reviewed)abstract
- The functional significance of fibrin deposits typically seen in inflammatory lesions, carcinomas and in healing wounds is not fully understood. In the present study, we demonstrate that fibrinogen/fibrin specifically bound to native Col I (collagen type I) and used the Col I fibre network as a base to provide a functional interface matrix that connects cells to the Col I fibres through alpha V beta 3 integrins. This allowed murine myoblast C2C12 cells to contract the collagenous composite gel via alpha V beta 3 integrin. We show that fibrinogen specifically bound to immobilized native Col I at the site known to bind matrix metalloproteinase-1, discoidin domain receptor-2 and fibronectin, and that binding had no effect on Col I fibrillation. A specific competitive inhibitor blocking the Col-I-binding site for fibrinogen abolished the organization of fibrin into discernable fibrils, as well as the C2C12-mediated contraction of Col I gels. Our data show that fibrin can function as a linkage protein between Col I fibres and cells, and suggest that fibrin at inflammatory sites indirectly connects alpha V beta 3 integrins to Col I fibres and thereby promotes cell-mediated contraction of collagenous tissue structures.
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| 26. |
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| 27. |
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| 28. |
- Rosander, Anna, et al.
(author)
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An IgG-binding protein A homolog in Staphylococcus hyicus
- 2011
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In: Veterinary Microbiology. - : Elsevier BV. - 0378-1135 .- 1873-2542. ; 149, s. 273-276
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Journal article (peer-reviewed)abstract
- Shotgun phage display was used to identify a homolog of the IgG-binding protein staphylococcal protein A in Staphylococcus hyicus type strain CCUG 15602/ATCC 11249. This bacterium is the causative agent of exudative epidermitis in pigs and can also cause mastitis in cattle. A protein with similar features as the originally identified protein A in Staphylococcus aureus was described; an YSIRK-type signal peptide, four IgG-binding domains, a putative peptidoglycan-binding domain, and a cell wall anchoring motif (LPXTG) was present. The highest degree of similarity was to a protein A homolog in Staphylococcus pseudintermedius. However, typical Xr polypeptide repeats present in the protein A of S. aureus and S. pseudintermedius could not be identified in the protein A of S. hyicus. The presence of the spa gene in ten porcine and eight bovine clinical isolates of S. hyicus was investigated by PCR. In all isolates, the spa gene could be detected but the amplicons were of two sizes. Sequence analysis of four selected PCR amplicons showed that only three IgG-binding domains were present in the protein A of clinical isolates generating a smaller spa fragment. The finding of spa in S. hyicus contributes to an increased understanding of potential virulence factors in this species. (C) 2010 Elsevier B.V. All rights reserved.
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| 29. |
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| 30. |
- Rosengren, Åsa, et al.
(author)
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Occurrence of foodborne pathogens and characterization of Staphylococcus aureus in cheese produced on farm-dairies
- 2010
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In: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605 .- 1879-3460. ; 144, s. 263-269
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Journal article (peer-reviewed)abstract
- The objective of this study was to address knowledge gaps identified in an earlier risk assessment of Staphylococcus aureus and raw milk cheese. A survey of fresh and short-time ripened cheeses produced on farm-dairies in Sweden was conducted to investigate the occurrence and levels of S. aureus, Listeria monocytogenes and Escherichia coil, to characterize S. aureus isolates with special emphasis on enterotoxin genes, antibiotic resistance, bio-typing and genetic variation, and to collect information related to production practices. In general, the hygienic quality of farm-dairy cheeses appeared to be of an acceptable microbiological quality, e.g. L monocytogenes and staphylococcal enterotoxin were not detected in cheese samples. However, E. colt and enterotoxigenic S. aureus were frequently found in raw milk cheeses and sometimes at levels that are of concern, especially in fresh cheese. Interestingly, levels in raw milk fresh cheese were significantly lower when starter cultures were used. Up to five S. aureus colonies per cheese, if possible, were characterized and about 70% of isolates carried one or more enterotoxin genes, most common were sec and sea. The Ovine biotype (73%) was most common among isolates from goat milk cheese and the Human biotype (60%) from cow milk cheese. Of all isolates, 39% showed decreased susceptibility to penicillin, but the proportion of isolates from cows' cheese (66%) compared to isolates from goats' cheese (27%) was significantly higher. S. aureus isolates with different properties were detected in cheese from the same farm and, sometimes even the same cheese. Isolates with the same pulsed-field gel electrophoresis (PFGE)-pattern were detected on geographically distant dairies. This indicates that multiple sources and routes of contamination are important. To improve the safety of these products efforts to raise awareness of the importance of hygiene barriers and raw milk quality as well as improved process control can be suggested, e.g. use of starter cultures and monitoring of fermentation with a pH-meter. For future safety assessments, a better understanding of factors determining toxin production in these cheeses is needed. (C) 2010 Elsevier B.V. All rights reserved.
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| 31. |
- Rönnberg, Elin, et al.
(author)
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Granzyme D Is a Novel Murine Mast Cell Protease That Is Highly Induced by Multiple Pathways of Mast Cell Activation
- 2013
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In: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 81, s. 2085-2094
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Journal article (peer-reviewed)abstract
- Granzymes are serine proteases known mostly for their role in the induction of apoptosis. Granzymes A and B have been extensively studied, but relatively little is known about granzymes C to G and K to M. T cells, lymphohematopoietic stromal cells, and granulated metrial gland cells express granzyme D, but the function of granzyme D is unknown. Here we show that granzyme D is expressed by murine mast cells and that its level of expression correlates positively with the extent of mast cell maturation. Coculture of mast cells with live, Gram-positive bacteria caused a profound, Toll-like receptor 2 (TLR2)-dependent induction of granzyme D expression. Granzyme D expression was also induced by isolated bacterial cell wall components, including lipopolysaccharide (LPS) and peptidoglycan, and by stem cell factor, IgE receptor cross-linking, and calcium ionophore stimulation. Granzyme D was released into the medium in response to mast cell activation. Granzyme D induction was dependent on protein kinase C and nuclear factor of activated T cells (NFAT). Together, these findings identify granzyme D as a novel murine mast cell protease and implicate granzyme D in settings where mast cells are activated, such as bacterial infection and allergy.
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| 32. |
- Rönnberg, Elin, et al.
(author)
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Infection of Mast Cells with Live Streptococci Causes a Toll-Like Receptor 2-and Cell-Cell Contact-Dependent Cytokine and Chemokine Response
- 2010
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In: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 78, s. 854-864
-
Journal article (peer-reviewed)abstract
- Mast cells (MCs) are strongly implicated in immunity toward bacterial infection, but the molecular mechanisms by which MCs contribute to the host response are only partially understood. We addressed this issue by examining the direct effects of a Gram-positive pathogen, Streptococcus equi, on bone marrow-derived MCs (BMMCs). Ultrastructural analysis revealed extensive formation of dilated rough endoplasmic reticulum in response to bacterial infection, indicating strong induction of protein synthesis. However, the BMMCs did not show signs of extensive degranulation, and this was supported by only slow release of histamine in response to infection. Coculture of live bacteria with BMMCs caused a profound secretion of CCL2/MCP-1, CCL7/MCP-3, CXCL2/MIP-2, CCL5/RANTES, interleukin-4 (IL-4), IL-6, IL-12, IL-13, and tumor necrosis factor alpha, as shown by antibody-based cytokine/chemokine arrays and/or enzyme-linked immunosorbent assay. In contrast, heat-inactivated bacteria caused only minimal cytokine/chemokine release. The cytokine/chemokine responses were substantially attenuated in Toll-like receptor 2-deficient BMMCs and were strongly dependent on cell-cell contacts between bacteria and BMMCs. Gene chip microarray analysis confirmed a massively upregulated expression of the genes coding for the secreted cytokines and chemokines and also identified a pronounced upregulation of numerous additional genes, including transcription factors, signaling molecules, and proteases. Together, the present study outlines MC-dependent molecular events associated with Gram-positive infection and thus provides an advancement in our understanding of how MCs may contribute to host defense toward bacterial insults.
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| 33. |
- Rönnberg, Elin, et al.
(author)
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Mast cells are activated by Staphylococcus aureus in vitro but do not influence the outcome of intraperitoneal S. aureus infection in vivo
- 2014
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In: Immunology. - : Wiley. - 0019-2805 .- 1365-2567. ; 143:2, s. 155-163
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Journal article (peer-reviewed)abstract
- Staphylococcus aureus is a major pathogen that can cause a broad spectrum of serious infections including skin infections, pneumonia and sepsis. Peritoneal mast cells have been implicated in the host response towards various bacterial insults and to provide mechanistic insight into the role of mast cells in intraperitoneal bacterial infection we here studied the global effects of S. aureus on mast cell gene expression. After co-culture of peritoneal mast cells with live S. aureus we found by gene array analysis that they up-regulate a number of genes. Many of these corresponded to pro-inflammatory cytokines, including interleukin-3, interleukin-13 and tumour necrosis factor-a. The cytokine induction in response to S. aureus was confirmed by ELISA. To study the role of peritoneal mast cells during in vivo infection with S. aureus we used newly developed Mcpt5-Cre(+) x R-DTA mice in which mast cell deficiency is independent of c-Kit. This is in contrast to previous studies in which an impact of mast cells on bacterial infection has been proposed based on the use of mice whose mast cell deficiency is a consequence of defective c-Kit signalling. Staphylococcus aureus was injected intraperitoneally into mast-cell-deficient Mcpt5-Cre(+) x R-DTA mice using littermate mast-cell-sufficient mice as controls. We did not observe any difference between mast-cell-deficient and control mice with regard to weight loss, bacterial clearance, inflammation or cytokine production. We conclude that, despite peritoneal mast cells being activated by S. aureus in vitro, they do not influence the in vivo manifestations of intraperitoneal S. aureus infection.
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| 34. |
- van Wieringen, Tijs, et al.
(author)
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The streptococcal collagen-binding protein CNE specifically interferes with {alpha}V{beta}3-mediated cellular interactions with triple helical collagen
- 2010
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 285:46, s. 35803-35813
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Journal article (peer-reviewed)abstract
- Collagen fibers expose distinct domains allowing for specific interactions with other extracellular matrix proteins and cells. To investigate putative collagen domains that govern integrin α(V)β(3)-mediated cellular interactions with native collagen fibers we took advantage of the streptococcal protein CNE that bound native fibrillar collagens. CNE specifically inhibited α(V)β(3)-dependent cell-mediated collagen gel contraction, PDGF BB-induced and α(V)β(3)-mediated adhesion of cells, and binding of fibronectin to native collagen. Using a Toolkit composed of overlapping, 27-residue triple helical segments of collagen type II, two CNE-binding sites present in peptides II-1 and II-44 were identified. These peptides lack the major binding site for collagen-binding β(1) integrins, defined by the peptide GFOGER. Peptide II-44 corresponds to a region of collagen known to bind collagenases, discoidin domain receptor 2, SPARC (osteonectin), and fibronectin. In addition to binding fibronectin, peptide II-44 but not II-1 inhibited α(V)β(3)-mediated collagen gel contraction and, when immobilized on plastic, supported adhesion of cells. Reduction of fibronectin expression by siRNA reduced PDGF BB-induced α(V)β(3)-mediated contraction. Reconstitution of collagen types I and II gels in the presence of CNE reduced collagen fibril diameters and fibril melting temperatures. Our data indicate that contraction proceeded through an indirect mechanism involving binding of cell-produced fibronectin to the collagen fibers. Furthermore, our data show that cell-mediated collagen gel contraction does not directly depend on the process of fibril formation.
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| 35. |
- von Beek, Christopher, et al.
(author)
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Streptococcal sagA activates a proinflammatory response in mast cells by a sublytic mechanism
- 2019
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In: Cellular Microbiology. - : WILEY. - 1462-5814 .- 1462-5822. ; 21:9
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Journal article (peer-reviewed)abstract
- Mast cells are implicated in the innate proinflammatory immune defence against bacterial insult, but the mechanisms through which mast cells respond to bacterial encounter are poorly defined. Here, we addressed this issue and show that mast cells respond vividly to wild type Streptococcus equi by up-regulating a panel of proinflammatory genes and by secreting proinflammatory cytokines. However, this response was completely abrogated when the bacteria lacked expression of sagA, whereas the lack of a range of other potential virulence genes (seeH, seeI, seeL, seeM, hasA, seM, aroB, pyrC, and recA) had no effect on the amplitude of the mast cell responses. The sagA gene encodes streptolysin S, a lytic toxin, and we next showed that the wild type strain but not a sagA-deficient mutant induced lysis of mast cells. To investigate whether host cell membrane perturbation per se could play a role in the activation of the proinflammatory response, we evaluated the effects of detergent- and pneumolysin-dependent lysis on mast cells. Indeed, exposure of mast cells to sublytic concentrations of all these agents resulted in cytokine responses of similar amplitudes as those caused by wild type streptococci. This suggests that sublytic membrane perturbation is sufficient to trigger full-blown proinflammatory signalling in mast cells. Subsequent analysis showed that the p38 and Erk1/2 signalling pathways had central roles in the proinflammatory response of mast cells challenged by either sagA-expressing streptococci or detergent. Altogether, these findings suggest that sagA-dependent mast cell membrane perturbation is a mechanism capable of activating the innate immune response upon bacterial challenge.
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| 36. |
- Werinder, Anna, et al.
(author)
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Genome characteristics related to the virulence of Streptococcus suis in Swedish pigs
- 2023
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In: Veterinary Microbiology. - 0378-1135 .- 1873-2542. ; 284
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Journal article (peer-reviewed)abstract
- The impact of S. suis on Swedish pig production has increased in recent years, and characterization of the strains present in the pig population is needed to aid in surveillance and prevention. Therefore, the aim of this study was to identify and characterize differences in the genomes between Swedish S. suis isolates associated with disease and isolates from healthy animals. Isolates categorized as being pathogenic (n = 100) or non-pathogenic (n = 117) were whole-genome sequenced, serotyped in silico, and sequence-typed using traditional MLST and coregenome MLST, and a genome-wide association study was performed to identify virulence-associated genes. In decreasing order, serotypes 2, 1, and 7 were the most common in the pathogenic group, and serotypes 15 and 12 were the most common in the non-pathogenic group. Among the commonly disease-associated sequence types, ST28 and ST25 were identified, whereas ST1 was scarcely found. The majority of isolates belonged to novel sequence types, revealing differences between Swedish isolates and those reported from other countries. The genomes of the pathogenic isolates were on average smaller and less heterogenic as compared to those of the non-pathogenic isolates. Although a majority of the previously published virulence-associated genes included in the study were found in the genomes of both pathogenic and non-pathogenic isolates, several new, significantly virulence-associated genes were identified.
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| 37. |
- Werinder, Anna, et al.
(author)
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Streptococcus suisin Swedish grower pigs: occurrence, serotypes, and antimicrobial susceptibility
- 2020
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In: Acta Veterinaria Scandinavica. - : Springer Science and Business Media LLC. - 0044-605X .- 1751-0147. ; 62
-
Journal article (peer-reviewed)abstract
- Background Streptococcus suisis a major cause of meningitis, arthritis, and pneumonia in pigs worldwide, and an emerging pathogen in humans. In Sweden,S. suishas previously received little attention but has in recent years become increasingly recognized as affecting the pig production. The aim of the present study was to investigate the occurrence, serotypes and antimicrobial susceptibility ofS. suisin Swedish grower pigs from herds with and without reportedS. suisassociated disease, as well as possible associations betweenS. suisassociated disease and selected environmental and production factors. Swab samples were taken from the tonsils of clinically healthy 8-13-week-old grower pigs from ten case herds and ten control herds. Isolates were cultured, identified using MALDI-TOF MS, and serotyped using latex agglutination. The antimicrobial susceptibility of 188 isolates was tested using broth microdilution. Production data was gathered and environmental parameters were measured on the farms. Results Streptococcus suiswas isolated from 95% of the sampled pigs in both the case and the control herds. Serotypes 3, 4, 5, 7, 9, 10, 11, 15, 16, and 17-34 were detected, although a majority of the isolates (81.5%) were non-typeable. There was less diversity among the serotypes isolated from the case herds than among those from the control herds; four and nine different serotypes, respectively. Isolates resistant to penicillin (3.8%) were reported for the first time in Sweden. Tetracycline resistance was common (88.4%). No association was noted between the production and the environmental factors investigated, and the carriership ofS. suis. Conclusions The carriership ofS. suiswas found to be higher in clinically healthy Swedish pigs than previously estimated, and for the first time, the presence of Swedish isolates resistant to penicillin was reported. Many of the most commonly disease-associated serotypes, e.g. serotypes 2, 9, 3, and 7, were detected in healthy grower pigs although further studies are needed to investigate the virulence of these isolates.
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| 38. |
- Werinder, Anna, et al.
(author)
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Whole-Genome Sequencing Evaluation of MALDI-TOF MS as a Species Identification Tool for Streptococcus suis
- 2021
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In: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 59
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Journal article (peer-reviewed)abstract
- Streptococcus suis is an important bacterial pathogen in pigs that may also cause zoonotic disease in humans. The aim of the study was to evaluate matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identification of S. suis case isolates from diseased pigs and tonsil isolates from healthy pigs and wild boar using sequence analysis methods. Isolates (n = 348) that had been classified as S. suis by MALDI-TOF MS were whole-genome sequenced and investigated using analyses of (i) the 16S rRNA gene, (ii) the recN gene, and (iii) whole-genome average nucleotide identity (ANI). Analysis of the 16S rRNA gene indicated that 82.8% (288 out of 348) of the isolates were S. suis, while recN gene analysis indicated that 75.6% (263 out of 348) were S. suis. ANI analysis classified 44.3% (154 out of 348) as S. suis. In total, 44% (153 out of 348) of the investigated isolates were classified as S. suis by all of the species identification methods employed. The mean MALDI-TOF MS score was significantly higher for the S. suis case isolates than for the tonsil isolates; however, the difference is of limited practical use. The results show that species confirmation beyond MALDI-TOF MS is needed for S. suis isolates. Since the resolution of 16S rRNA gene analysis is too low for Streptococcus spp., ANI analysis with a slightly lowered cutoff of 94% may be used instead of, or in addition to, recN gene analysis. Supplementation of the MALDI-TOF MS reference library with mass spectra from S. orisratti, S. parasuis, S. ruminantium, and additional S. suis serotypes should be considered in order to produce more accurate classifications.
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